Whatever Type of Screw Chiller,
TopChiller Can Fulfill the Chiller Solution for You.
- Over 20 years of screw chiller manufacturing experience: TopChiller specialized in screw chiller design and manufacturing over 20 years
- 24 months warranty time: TopChiller promise standard 12 months warranty can extend to 24 months covered all screw chillers
- Using famous brand spare parts: Each screw chiller from TopChiller uses a famous compressor and refrigeration spare parts
- Technical support& Training service: TopChiller can provide screw chiller installation and on-site commission service
- 8 Hours troubleshooting: We promise 8 Hours quick response to solve your screw chiller if the case of any screw chiller error or alarm
- Free screw chiller solution: TopChiller give all clients screw chiller and central chiller solutions free of charge
Why TopChiller Can Be Your Reliable Screw Chiller Manufacturer and Supplier
Your Premier Screw Chiller Manufacturer and Supplier Over 20 Years
TopChiller is your reliable screw chiller manufacturing company in china with 20-year experience.
As a professional screw chiller manufacturer, TopChiller has a full range of all models of screw chillers from 50 tons to 550-ton cooling capacity.
High-quality screw chillers designed and manufactured by TopChiller have outstanding advantages including:
1. High efficient semi-hermetic compressor, the heart of the screw chiller – imported high-quality screw compressor, its 5: 6 super-efficient screw rotor compressor, 20-30% higher than the general compressor, high reliability and efficiency, easy maintenance, capacity control, wide application range.
2. The microcomputer controls the temperature accurately, realizes the full function of automatic control. The touch screen is sealed well, waterproof, dustproof, corrosion-resistant, and the key life is long. Classified and non-polar energy control, equipped with 100%, 75%, 50%, 25% classified energy control system, to ensure the screw chiller can play the role of energy-saving in partial load.
3. High efficiency. The heat exchanger adopts efficient bellows and a high-efficiency screw compressor to ensure the high efficiency of the unit
4. The screw chiller has the following components to prevent any operation failure: compressor protection design timer, over-current relay, compressor motor temperature sensor, antifreeze junction temperature controller, sight glass, oil heater, compressor reverse phase protection relay, high and low-pressure protection, exhaust high-temperature protection, safety valve, soluble plug
5. The water-cooled screw chiller adopts horizontal shell and tube condenser and shell and tube evaporator, with simple structure, stable heat exchange, long efficiency, and convenient maintenance
6. The control system of the screw chiller adopts the imported PLC program controller, the human-machine interface is equipped with a large screen touch screen, the interface is simple and easy, and the operation is intuitive and simple.
7. The screw chiller has a reliable safety protection device, including a high and low voltage protector, exhaust overheat protector, compressor motor overheat protector, overload current protector, antifreeze temperature protector, water flow protector, and emergency stop switch
8. A different refrigerant such as R407c, R134a, R410a, and R404a are available depending on the working condition and ambient temperature.
Compared with an air-cooled screw chiller, a water-cooled screw chiller needs an external cooling tower and cooling pump running together.
You will benefit a lot by using a water-cooled screw chiller:
1. Compact structure, stable operation:
The condenser and dry evaporator of the screw chiller adopt a heat transfer tube, and the main engine adopts an imported semi-hermetic screw compressor, which has many advantages such as compact structure, small volume, lightweight, and small installation position. The semi-hermetic screw compressor has few moving parts.
The compressor adopts a 5:6 super screw rotor. There is no direct wear between the rotors, and the reliability is high. Because the screw chiller is a continuous compressor without pulsation, the screw chiller has the characteristics of stable performance, low noise, small vibration, and stable operation.
It is 20% – 30% more efficient than the reciprocating compressor and has obtained IS09001 certification and many countries in Europe and America;
2. Perfect energy control system:
Screw chiller has a four-stage capacity control system, energy regulation: [100, 75, 50, 25 (or start, 0%], self-regulating screw chiller unit start and stop according to load change, more energy saving. During operation, the computer control system will change the screw chiller’s energy output according to the client’s heat load change.
By monitoring the difference between the actual load measured and the user’s setting, the microcomputer can quickly judge the signal to push the slide valve to the required energy.
And in many systems, the optimization of Zui’s low power consumption when using Zui’s good cooling output not only shows excellent performance at full load but also has high operating efficiency even at partial load;
3. Independent operation of refrigeration system:
A large capacity screw chiller has two or more independent refrigeration circuits, which can make one circuit fail/maintain and the other circuit operates normally.
It has a standby function, especially suitable for the industrial environment without shutdown;
4. Easy and intuitive operation:
Screw chiller adopts microcomputer programmable controller (PLC display in English), touch screen display, select operation according to the menu on the screen, directly touch the display button on the screen with your finger to start the water-cooled screw chiller.
The screen can display the operation status of the screw chiller at any time, and it can be displayed in two ways of graphic and text table parameters at a glance;
5. Protection function of microcomputer controller:
Screw chiller has the functions of compressor coil over-temperature protection, oil preheating timing switch, cold water flow switch, cold water outlet over-temperature protection, Y – △ start failure protection, exhaust over-temperature protection, compressor overload protection, power down memory function, frequent start and stop protection, abnormal voltage protection, oil level over low protection, high and low-pressure protection, etc Protection function;
6. Multiple protection, safe and reliable:
Screw chiller in addition to the compressor internal protection module to provide overpressure, lack of phase, overload and other functions to protect the compressor, the pressure control and other devices of the refrigeration system can make the screw chiller work without fail;
in addition to the compressor internal protection module to provide overpressure, lack of phase, overload, and other functions to protect the compressor, the refrigeration system The pressure control device can make screw chiller work without fail;
7. Easy to install:
The screw chiller has completed all parts installation, operation tests in the factory, and has been filled with refrigerant and refrigeration oil. Users only need to connect water pipe water and circuit connection to put into use, reducing installation and commissioning time
As a professional screw chiller manufacturer, TopChiller has exported hundreds of screw chillers from 50 ton,85 ton, 100 ton, 120 ton, 150 ton up to 200 ton-250 ton throughout the world.
If you are waiting for a professional screw chiller supplier?
If you are looking for a high-quality screw chiller manufacturer?
TopChiller is your best screw chiller choice in the refrigeration field.
If you have any screw chiller inquiries, please do not hesitate to contact TopChiller sales to get your screw chiller price.
A Screw Chiller is a famous cooling unit that uses water or air for cooling in heat-producing industrial applications. The screw compressor is the determinant component for the cooling effect, which is significant for the normal working of such applications.
As the refrigerant flows through the refrigerant coils undergoing the transition from one form to another, the heat is absorbed from the system. The absorbed heat is then transferred to the chilled water or ambient air currents passing through the coils.
Primarily equipped with a screw compressor, a Screw Chiller designed by TopChiller comes in a smart design. Expansion valves, condenser, evaporator, and accessories like VFDs, filters, and fans help run the normal refrigeration cycle.
Due to silent operation and higher efficiency Screw Chiller manufactured by TopChiller has extensive applications. The laser industry, semiconductor industry, food, and beverage industry, welding and molding industry, plastic industry, and many more are currently using it for smooth functioning.
TopChiller has earned the title of producing the highest quality Screw Chiller with the unique features to match the highest standards. We are proud of our highly qualified engineering and technician staff for their unmatched hard work.
Whether you are looking for a complete package with affordability and quality, or you’re focused on the efficiency of the Screw Chiller, TopChiller has got you all sorted. For a better understanding of all the features and properties of different models of our Screw Chiller, call on our customer care service, which is open 24/7.
Features and Advantages:
A Screw Chiller is designed with particular attention to unique features for added advantages. These features have been described below:
- It conforms to the codes and standards of AHRI 550/590. Other standards include ANSI/ASHRAE 34 and ASME Section VIII. This enables you to have close monitoring to improve efficiency with passing the time.
- The semi-hermetic twin-screw compressor can accommodate high loads with more excellent reliability. There are 5-6 patented screw rotors that guarantee higher efficiency.
- A non-fused disconnect switch that has a single power connection. It is a safe and secure way to carry out any maintenance during which the unit has to be disconnected.
- The basic communication protocol is supposed to be the Modbus protocol. However, it uses higher-level communication methods like BACnet and Lonwork, etc.
- Due to the advanced capacitors, there are power factor corrections that maintain a 95% displacement power factor.
TopChiller: Your Premier Screw Chiller Manufacturer and Supplier in China
Screw chillers having air-cooled screw chiller and water-cooled screw chiller in terms of cooling method.
Compared with scroll compressor chillers, screw chillers with large cooling capacity for some certain industrial or commercial usage.
Both types of these two screw chillers are widely used for various industries applications such as HAVC, big building&hotel air conditioning, central chilled water supply, chemical processing, die casting,food&beverage processing, pet food, Pharmaceutical, plastic processing, automotive, energy&power project, packing, and printing…
Screw chiller expertise is common in all major industries, it uses the screw compressor to get this name.
The utility of screw chiller has the advantages of large power, compact structure, stable operation, simple operation, and wide application range, and is suitable for large air conditioners such as hotels, hotels, factories, hospitals, etc., especially in high-rise buildings with less load, and can display its uniqueness superiority.
Screw Chiller: The Completely Buying Guide for Importer
- What is a Screw Chiller?
- What is the difference between Screw Chillers and Reciprocating Chillers?
- Screw chiller working principle and flow diagram
- Features of water-cooled screw chiller:
- Advantages of screw chillers
- Screw chiller applications:
- Some tips for selecting a correct screw chiller
- Why does the screw compressor need refrigeration oil or lubrication oil?
- Why TopChiller can be your reliable screw chiller supplier?
- Common fault analysis of screw chillers
- Selection points and troubleshooting of screw chillers
- Installation and commissioning of screw chiller
1. What is a Screw Chiller?
A screw chiller is an industrial chiller with a screw-type compressor.
Like all chilling systems, screw chillers are composed of an evaporator, compressor, condenser, expansion valve.
What sets it different from other types of chillers is its screw-type compressor, which uses two helical rotors that propel and compress the refrigerant vapor.
Because of fewer moving parts and the rotary motion, screw chillers are more durable and quiet. They are smaller and lighter and are a popular choice by the users.
Screw chillers can be applied in a variety of cooling applications and are reliable for heavy-duty performance under harsh conditions and the environment.
2. What is the difference between Screw Chillers and Reciprocating Chillers?
Regardless of which type of compressor, all of them have one common function-converting a source of power into stored energy in the form of compressed air.
Simply speaking, a compressor sucks in enough air and decreases its volume.
As a result both the temperature and pressure rise. Most air compressors either are reciprocating piston type or rotary screw type.
2.1 Reciprocating Chiller
A reciprocating compressor has a piston move downwards, reducing the pressure in its cylinder by creating a vacuum.
This difference in pressure forces the cylinder door to open and bring gas in. When the cylinder goes back up, it increases pressure, thus forcing the gas back out. The up-and-down motion is called reciprocating motion.
There are a lot of moving parts like piston, piston ring, crankshaft, connecting rod, valves, etc. that cause lesser reliability and more chance of breakdown.
The internal temperature at which the pistons operate is around 150 to 200 Deg C. This is because of the friction generated by the contact of piston rings against the cylinder walls.
The space required by the piston compressor is more. A separate screw-type compressor compartment is needed for its noise and vibration.
Small compressors are air-cooled screw chillers but large screw chillers from 30HP and above are only water-cooled screw chillers.
2.2 Screw Chillers
For a study of screw chillers, we must know something about screw compressors.
The screw refrigeration compressor is a kind of rotary refrigeration compressor and has both a piston-type and power type (speed type).
Features of screw compressors:
- 1) Compared with reciprocating piston refrigeration compressors, screw compressors have a series of advantages such as high speed, lightweight, small size, small footprint, and low exhaust pulsation.
- 2) The screw compressor has no reciprocating mass inertia force, good dynamic balance performance, stable operation, small vibration of the machine base, and the foundation can be made smaller.
- 3) The screw compressor has a simple structure, a small number of parts, and no wearing parts such as a gas valve and a piston ring. Its main friction parts such as a rotor and a bearing have high strength and wear resistance, and are lubricated. The condition is good, so the machining amount is small, the material consumption is low, the operation cycle is long, the use is relatively reliable, the maintenance is simple, and the operation automation is facilitated.
- 4) Compared with the speed compressor, the screw compressor has the characteristics of forced air transmission, that is, the displacement is almost independent of the exhaust pressure, and the surge does not occur at a small displacement, and is broad. High efficiency can still be maintained within the working conditions.
- 5) using the slide valve adjustment, can achieve energy step-less adjustment.
- 6) The screw compressor is not sensitive to the liquid inlet and can be cooled by injection. Therefore, at the same pressure ratio, the discharge temperature is much lower than that of the piston type, so the single-stage pressure ratio is high.
- 7) there is no clearance volume in the screw compressor, so the volumetric efficiency is high.
1. Inhalation process:
The screw-type intake side suction port must be designed so that the compression chamber can fully inhale, and the screw-type air compressor has no intake and exhaust valve groups, and the intake air is only adjusted by opening and closing of a regulating valve.
When the rotor rotates, the space of the groove of the main and auxiliary rotors is the largest when it is turned to the opening of the intake end wall.
At this time, the space of the groove of the rotor communicates with the free air of the intake port, because the groove of the air is exhausted.
The air is exhausted in its entirety. At the end of the exhaust, the groove is in a vacuum state.
When it is turned to the intake port, the outside air is sucked and flows into the groove of the main and auxiliary rotors in the axial direction.
Screw air compressor maintenance reminds us that when the air fills the entire tooth groove, the air intake side ends face of the rotor turns away from the air inlet of the casing, and the air between the tooth grooves is closed.
2. Closure and transportation process:
At the end of the inhalation, the main and auxiliary rotors will be closed with the casing and the casing will be closed.
At this time, the air is not closed in the groove, that is, [closed process].
The two rotors continue to rotate, and the tooth peaks coincide with the groove at the suction end, and the mating surface gradually moves toward the exhaust end.
3. Compression and injection process:
During the conveying process, the engaging surface gradually moves toward the exhaust end, that is, the gap between the engaging surface and the exhaust port gradually decreases, and the gas in the groove is gradually compressed, and the pressure is increased, which is [compression process].
At the same time, the lubricating oil is also injected into the compression chamber and mixed with the chamber gas due to the pressure difference.
4. Exhaust process:
When the meshing end face of the rotor in the maintenance of the screw air compressor is turned into communication with the exhaust of the casing, (the pressure of the compressed gas is the highest), the compressed gas starts to be discharged until the meshing surface of the tooth peak and the groove moves to the exhaust.
End face, at this time, the space between the two rotor meshing surfaces and the casing exhaust port is zero, that is, the completion (exhaust process), at the same time, the length of the groove between the rotor meshing surface and the casing air inlet reaches a long time, the inhalation process is going on.
5. Lubricating oil and capacity adjustment system for screw chiller
The main functions of lubricating oil in screw chiller compressors are lubrication, cooling, and capacity adjustment.
The oil pressure in the piston-cylinder pushes the piston and spool to move forward/backward in the compression chamber.
In particular, the differential pressure oil supply system in the Handbell RC-2 series can eliminate the use of external oil pumps in piston compressors.
However, in some special applications, an external oil pump is still required to ensure the safe operation of the screw chiller.
The bearings in the RC-2 series Hanbell screw compressors only need to provide a small amount of oil for lubrication.
The oil injected into the compression chamber can form an oil film in the compression chamber to increase the efficiency of the compressor and absorb some of the heat generated in the above process.
To separate the lubricating oil mixed from the refrigerant gas, an oil separator is required to ensure that as little oil as possible is carried into the screw chiller refrigeration system.
Pay special attention to the temperature of the lubricant, which is an important factor affecting the life of the compressor bearing.
High lubricating oil temperature will reduce the viscosity of the oil, resulting in a decrease in the lubricating ability and heat absorption capacity of the lubricating oil.
It is recommended to keep the viscosity of the lubricating oil above 10 mm2/s.
The oil temperature should be kept above the system condensation temperature to avoid the migration of refrigerant into the system during the summer.
When the ambient temperature is too low, the viscosity of the lubricating oil is high.
In this case, the pressure drop of the oil passage in the oil passage is too large to be properly loaded, resulting in a heavy load starting of the compressor.
It is recommended to equip the oil heater to heat the oil to increase the oil temperature in a short time.
If the compressor is operating under extreme conditions, an external oil cooler is also required. Have Hanbell determine the amount of cooling required for the oil cooler and the oil flow.
It is recommended to use some lubricating oil with high viscosity under the conditions of severe working conditions.
At this time, the exhaust temperature is higher, which can lower the viscosity of the lubricating oil and ensure the proper viscosity of the lubricating oil.
In addition, there may be a phenomenon in which the amount of oil returned from the evaporator is insufficient, such as a flooded refrigeration system, etc., and oil return is difficult in these systems, resulting in loss of oil in the compressor.
If there is a problem of insufficient oil return in the system, it is recommended to install a secondary oil separator between the compressor venting condenser of the screw chiller to further reduce the oil entering the system.
1. It is recommended to install the optional oil level switch to avoid malfunction of the compressor oil level.
2. The screw compressor can withstand a certain short liquid attack concerning the piston compressor, but the long-term liquid compression affects the viscosity of the lubricating oil, and the bearing lubrication is insufficient, which easily causes the compressor to be stuck.
Screw chiller four-stage capacity adjustment system load status sharing:
25% (33%) load
When the compressor of the screw chiller is started, the solenoid valve is activated and the piston is at the 25% (33%) load position.
In this state, the high-pressure oil coming from the fuel tank is continuously injected into the piston cylinder through the capillary tube, and the high-pressure oil in the piston cylinder is directly bypassed to the suction port.
At this time, all the pistons remain in their initial positions.
Note: The 25% load condition is designed to shorten the start-up time only, avoiding the motor starting current being maintained for a long time and tripping protection.
Do not operate for a long time under the 25% load state after the start-up process. It should be directly loaded and operated (especially under a large differential pressure/pressure ratio) to prevent damage to the rotor, bearings, and other components due to excessive compressor discharge temperature that will affect the screw chiller operation.
50% (66%) load
When the 50%/66% solenoid valve is activated by the temperature control, the power failure is turned off by 25%, and the high-pressure oil coming from the fuel tank flows into the piston cylinder, pushing the piston to the right when moving to 50%/66%.
Since the high-pressure oil is returned from the oil discharge hole through the 50%/66% to the suction port, the piston stops operating at this position, and the compressor of the screw chiller is kept at the load state of 50%/66%.
AdvantaWhen the screw chiller 75% solenoid valve is activated, the 50% solenoid valve is turned off when the power is turned off, and the high oil pressure pushes the piston to continue to move to the right.
When moving to 75%, the high-pressure oil is returned from the oil discharge hole through 75% to The suction port, so the piston stops running at this position, and the compressor of the screw chiller is kept at 75% load. ge of semi-hermetic screw compressor.
When we turn off all the solenoid valves of the screw chiller, the high oil pressure continues to flow into the piston cylinder, gradually pushing the piston to the suction side.
When the slide valve contacts the dead center of the compression chamber, the piston also reaches. Its dead center position, at this time there is no phenomenon of bypassing the compressed gas.
At this time, the compressor of the screw chiller reached full load operation.
Spray cooling motor, motor working temperature is low, long life; open compressor uses an air-cooling motor, motor working temperature is high, affecting motor life, screw chiller installation room working environment is poor; using exhaust cooling motor, the motor working temperature is very high, The motor has a short life.
Generally, the external type of oil is large in volume, but the efficiency is high; the built-in oil is combined with the compressor, and the volume is small, so the effect is relatively poor.
The secondary oil splitting effect can reach 99.999%, and the compressor can be well lubricated under various working conditions.
They sit slightly off-center in a shaft, with one side always touching the wall.
As they move at high speeds, they accomplish the same goal as the reciprocating compressor-one part of the shaft is always at a different pressure than the other, so gas can come in at the low-pressure point and exit at the high-pressure point.
The screw compressor has a male and a female rotor. The male rotor drives the female rotor if it is an oil-injected screw compressor technology, and a timing gear drives both rotors in the oil-free compressor technology as both rotors will run harmonically with minimum calculated clearance between both elements.
The basic principle of a screw compressor is as the male and female rotors are rotating in the opposite direction, they draw air in between them.
As the air progresses along with the rotors the air is compressed as the volume space between the rotors decreases, hence creating compressed air that is displaced to the outlet.
2.3Advantages and Disadvantages of Screw Chillers compared to Piston Chillers
1)Less possibility to break down: As the screw compressor has only two moving parts that are not in contact with each other, so there is no wear or tear, and hence it is less possible to break down.
2)Less noise: In a screw compressor, the screws rotate in one direction and thereby causing less noise, heat, and vibration. Furthermore, the screw compressor is skid mounted and therefore foundation is not required.
3)Suitable for continuous operation: For the above reasons, screw compressors are suitable for 24 hours of continuous operation.
4)Energy-saving: More airflow at less power consumed. The difference is more beneficial viable at 20HP and above machines.
5)Compact in size: Screw compressors are smaller in size and lighter in weight and can be installed in a sealed compartment.
6)Resistant to harsh conditions and environment: Taken care of in the right way, this compressor can last around 2 to 5 times longer than the piston compressor.
1)Higher Price: Compared to a piston compressor, screw compressors are pricey.
2)Higher lubricant consumption: It has a complicated lubricating system and thus consumes more lubricant.
3)High precision installation requirements: Installation required higher precision and techniques.
3. Screw chiller working principle and flow diagram
Generally, there are 2 types of screw chillers: air-cooled screw chiller and water-cooled screw chiller
Let’s have a look at how these two types of screw chiller work and their flow diagram as below:
For air-cooled screw chiller:
The air-cooled screw chiller has a key component as the semi-hermetic screw type compressor, and the air-cooled screw chiller unit is out of the evaporator as a gas refrigerant;
After the screw compressor is adiabatically compressed, it becomes a high temperature and high-pressure state.
The compressed gas refrigerant is condensed by isostatic cooling in a condenser, and after condensation, it is changed into a liquid refrigerant, and then expanded to low pressure through a throttle valve to become a gas-liquid mixture.
The liquid refrigerant under low temperature and low pressure absorbs the heat of the cold matter in the evaporator and becomes a gaseous refrigerant again.
The gaseous refrigerant re-enters the compressor through the pipeline and begins a new cycle. These are the four processes of the refrigeration cycle.
This is also the main working principle of the air-cooled screw chiller.
The evaporator is one of the most important parts in both air-cooled screw chillers and water-cooled screw chillers.
There are 3 types of evaporators or coolers for screw chillers.
1. Dry Shell and Tube Evaporator
The dry evaporator refrigerant passes through the heat exchanger tube, and the cold water runs outside the high-efficiency heat exchange tube.
The heat exchange efficiency of such a heat exchanger is relatively low, and the heat transfer coefficient is only about twice the heat transfer coefficient of the light pipe.
But the advantage is that it is easy to return oil, and the control is relatively simple, and the charging amount of the refrigerant is about 1/2 to 1/3 of the filling amount of the full liquid type unit.
2. Flooded evaporator
The operation of the flooded evaporator and dry evaporator is exactly the opposite.
The cold water passes through the heat exchange tube, the refrigerant completely immerses the heat exchange tube, and absorbs heat, and evaporates outside the heat exchange tube.
There are many needle-shaped holes on the surface of the heat transfer tube of the Flooded evaporator, and there are spiral protrusions on the inner surface of the tube to enhance the heat exchange on the cold waterside.
The high-efficiency heat transfer tube that simultaneously enhances the boiling outside the tube and the heat transfer inside the tube increases the heat transfer coefficient by about 5 times compared with the light tube.
3. Falling film evaporator
Falling film evaporators, also known as spray evaporators, are similar to full liquid evaporators, but they differ from full liquid evaporators.
The refrigerant of the evaporator is sprayed from the upper part of the heat exchanger to the heat exchange tube, and the refrigerant only forms a thin film of cold liquid on the heat exchange tube, so that the refrigerant is reduced in boiling evaporation.
The static liquid level pressure increases the heat exchange efficiency, and the heat exchange efficiency is increased by about 5 times compared with the full flooded screw chiller.
Falling film evaporation is flow boiling. Since the thickness of the liquid film on the outer surface of the tube is small, the boiling point without static pressure increases, and the heat transfer coefficient is high.
The bubbles generated by flooded evaporation (that is, immersed evaporation) tend to accumulate on the surface of the heat exchange tube, resulting in a decrease in heat exchange efficiency, and the heat transfer effect is not as good as that of falling film evaporation.
In general, falling film evaporation is a small temperature difference, but it is necessary to prevent fouling and affect heat transfer efficiency.
In summary: The Flooded type means that the refrigerant is between the copper tube and the shell tube, and the chilled water flows inside the copper tube.
The dry type evaporator is the opposite of the two. The refrigerant evaporates in the copper tube, and the water flows between the copper tube and the shell tube.
They are mainly used for the heat pump air conditioner. In industrial low-temperature chillers, ordinary dry evaporators are generally used.
“Flooded” means that the “shell-and-tube evaporator” used in the unit adopts the “flooded evaporator”, which is a shell-and-tube evaporator that is different from “dry” and “falling-film”.
Its “shell process” takes the refrigerant cycle, and the “tube process” takes the chilled water cycle. From the cross-section, it is as if there is a large cylinder of refrigerant in the cylinder, and the water pipe bundle is immersed in the refrigerant.
It is just the opposite of the “dry evaporator”. The dry type is the “tube” refrigerant, and the “shell” water is like the refrigerant tube bundle soaked in the water.
The Flooded evaporator and the flooded screw chiller have higher heat transfer efficiency than the dry evaporator/dry screw chiller unit, and the temperature difference between the outlet water temperature and the evaporation temperature is small, and the resistance along the path is small.
which is suitable for units with large circulation ( For example, the centrifuge), the cooling effect is good. However, refrigerant charge requirements are large and a dedicated oil return system is required to help the compressor return oil.
Advantages and disadvantages of dry and flooded evaporators
The Flooded shell and tube evaporator run water in the tube, and the refrigerant evaporates outside the tube cluster, so the heat transfer surface is basically in contact with the liquid refrigerant.
Generally, the amount of refrigerant charged in the casing is about 55% to 65% of the effective volume of the cylinder, and the refrigerant liquid is heated and vaporized and then returned to the compressor through the liquid separator at the top of the cylinder. Easy operation and management, high heat transfer coefficient.
The disadvantages are:
1 When the evaporation temperature of the refrigeration system is lower than 0 °C, the water in the pipe is easy to freeze and destroy the evaporation pipe.
2 The refrigerant is filled in a large amount
3 Influenced by the height of the refrigerant liquid column, the evaporation temperature at the bottom of the cylinder is high, which will reduce the heat transfer temperature difference
4 The lower part of the evaporator cylinder will accumulate oil, and there must be reliable oil return measures, otherwise, it will affect the safe operation of the system.
The dry shell tube type, that is, the refrigerant of the non-full liquid evaporator flows in the tube, and the water flows outside the tube cluster.
There are usually several processes for refrigerant flow. Due to the gradual gasification of the refrigerant liquid, the higher the flow rate, the more the number of process tubes.
To increase the water side heat exchanger, a plurality of baffles are arranged on the outer side of the tube heat transfer tube, so that the water flows across the tube cluster multiple times.
The advantages are:
1 Lubricating oil enters the compressor with the refrigerant, there is generally no problem of oil accumulation
2 fewer refrigerants are filled, generally only about 1/3 of the full liquid type;
When 3t0 is around 0 °C, the water will not freeze.
However, the use of this evaporator must be noted:
1 There are multiple processes for the refrigerant. If the end cover is not well treated, it will produce effluent, which will make the liquid entering the next process unevenly distributed and affect the heat transfer effect
2 There is a leakage problem on the waterside. Because there is a gap of 1~3mm between the outer edge of the baffle and the casing, and there is a gap of about 2mm between the heat transfer tube, water leakage will occur.
The practice has proved that water leakage will cause the waterside heat transfer coefficient to decrease by 20% to 30%, and the total heat transfer coefficient by 5% to 15%.
4. Features of air-cooled screw chiller:
1. Semi-hermetic screw-type high-efficiency compressor, with single-machine system and dual-machine series selection, the unit is compact in structure and convenient in maintenance; adopts the new 5:6 screw rotor design, stable operation, high efficiency, and energy-saving.
2. Advanced intelligent frosting method. Microcomputer control analyzes the temperature of each point at any time, optimizes the defrost cycle time, and ensures that the defrost does not affect the normal operation of the equipment in time.
3. Professional motor cooling unit. Meet the operating conditions of severe working conditions.
4. With a new generation of high-efficiency heat exchange tubes, the heat transfer coefficient can be increased by 5%.
The double-slot tube-plate design and advanced tube expansion technology make the structure more sealed and reliable, completely avoiding the possibility of mutual penetration.
For water-cooled screw chiller：
When the water-cooled screw chiller is working, the screw compressor draws the low-temperature and low-pressure refrigerant in the evaporator into the cylinder, and the compressor steam is compressed into high-temperature and high-pressure refrigerant, then enters the condenser through the exhaust pipe.
The high temperature and high-pressure refrigerant gas exchanges heat with the cooling water in the condenser, transfers heat to the cooling water, and the refrigerant gas condenses into a high-pressure liquid.
The high-pressure liquid from the condenser is throttled and depressurized by the thermal expansion valve and then enters the evaporator.
In the evaporator, the low-pressure liquid refrigerant absorbs the heat of the chilled water and vaporizes, so that the chilled water is cooled and cooled to become the required low-temperature water.
The vaporized refrigerant gas is again sucked into the compressor for compression and is discharged into the condenser.
So that it is continuously circulated and continuously circulated, thereby achieving cooling of the chilled water.
A water-cooled screw chiller must go along with a cooling tower, water pump, insulation water tank, to make a complete water cooling system.
Features of water-cooled screw chiller:
Efficient semi-hermetic screw compressor, the screw chiller runs smoothly and the noise is low.
Inspiratory cooling results in low motor operating temperatures and long motor life.
With high-quality bearings, the bearing life is at least 40,000 hours. Built-in oil separator for smaller size and better results.
It can be safely implemented in the range of 0% to 100% or stepless energy regulation to maximize power conservation.
The condenser adopts a high-efficiency shell-and-tube heat exchanger (optional stainless steel plate heat exchanger), built-in high-efficiency heat exchange tooth tube, reasonable design, and good heat exchange effect;
The evaporator adopts a high-efficiency shell-and-tube heat exchanger (optional stainless steel plate heat exchanger), built-in high-efficiency heat exchange tooth tube, reasonable design, and good heat exchange effect;
Suitable for R22, R407c, R134a, R404A, and other working fluids.
Less moving parts and low failure rate. An economizer can be selected to further increase compressor refrigeration capacity and efficiency.
A spray chiller can be selected to extend the range of applications for the compressor.
Oil cooling can be selected to increase compressor efficiency and compressor application.
Advantages of screw chillers
There are advantages of using screw chillers:
1. Screw chiller with simple structure, less moving parts, less wearing parts, only 1/10 of the piston type, low failure rate, and long service life.
2. The circular motion is stable, there is no surge phenomenon during the low load operation, low noise, and low vibration.
3. The compression ratio can be as high as 20 and the EER value is high.
4. Convenient adjustment, the stepless adjustment in the range of 10%~100%, high efficiency in partial load, and significant power saving.
5. Small size, lightweight, can be built as a fully enclosed large capacity screw chiller unit.
6. Not sensitive to wet strokes.
7. It is a positive pressure operation, and there is no problem with the intrusion of outside air.
Screw chiller applications:
Screw chillers are widely used both in industrial applications and commercial fields:
1. Screw chiller for industrial application
Screw chillers can provide 5~15°C chilled water, or use ethylene glycol solution as the coolant.
Screw chillers can also provide a -5~+5°C process frozen aqueous solution, which can be used as ice storage, low-temperature air supply, central air conditioning, and other production processes.
At the same time, according to the requirements of the user, TopChiller can specially design the screw chiller to provide a large temperature difference range (the temperature difference between the inlet and outlet water is 8~15°C).
Or higher than the water-cooled screw chiller (outlet water temperature 15 ° C ~ 25 ° C). The cooling capacity is 94KW-3360KW.
2, medium temperature screw chiller
The outlet water temperature is -5 ° C ~ -45 ° C, using imported semi-closed screw compressor chiller(with economizer); can provide -5 ° C ~ -45 ° C low temperature.
Ethylene glycol solution or brine solution can be used as a cold source for chemical, pharmaceutical, cold storage, an ice rink, and other processes.
The cooling capacity of this kind of screw chiller is 55KW-2000KW.
3, low-temperature screw chiller
The effluent temperature is -45 ° C ~ -110 ° C, can provide -45 ° C ~ -110 ° C alcohol or calcium chloride aqueous solution chilled water; using a binary stack or ternary cascade screw refrigeration system. High energy efficiency ratio and stable operation.
At the same time, screw chillers can be designed according to the requirements of users, ultra-low temperature type, anti-corrosion type, explosion-proof type special industrial screw type chiller, which can meet the requirements of various industries for process cold source.
Nowadays, the use of screw chillers is seen in many industries. For this screw chiller, which different industries can be used in the application process, to allow users in different industries to choose more for more understanding.
let’s take a brief look at some of the screw chiller applications.
First, the construction industry
Screw chillers can be used in some construction industries.
There are many places used in the construction industry.
For example, it can supply chilled water to concrete, and it can change the molecular structure of concrete.
In the process of construction, it is more suitable for use, and its application can also invisibly play a role in the hardness and toughness of concrete, so it is now seen in many construction industries.
The development in this industry will also become larger and larger, and users who have processed in this industry can choose to use this screw chiller.
Second, the food industry
This type of screw chiller can also be used in some food industries.
We all know that after many foods are processed, they need to be packaged, but the food heated by high temperature needs to be cooled when it is put into the package.
The screw chiller can play such a role, allowing the hot food to cool quickly and fit into the bag, so it is still used in this food industry.
Third, Big factory or central air conditioning of HVAC
The cooling capacity of the screw chiller is higher than that of the scroll chiller.
So this screw chiller can be mainly used in chemical plants, ink printing plants, automobile manufacturers or central air conditioning systems, or other large industrial refrigeration.
The above is the application of screw chillers in the construction, food industries, air conditioning for big buildings.
Now with the development of various industries, the application of such screw chillers will gradually increase, and it will become a must in many industries in constant innovation.
Some tips for selecting a correct screw chiller
In industrial production, mechanical equipment generates heat during operation.
If this heat cannot be dissipated in time, it will affect the normal operation of the equipment as well as the quality and production efficiency of the product.
Another situation is that the processed product needs to reach a certain temperature during processing to be processed normally or to achieve higher yield and production efficiency.
Then the temperature of the processed product must reach the desired temperature before or during processing.
At this time, it’s showing the time of the screw chiller
But how to size a suitable screw chiller for your business?
- Cooling capacity
The cooling capacity of the screw chiller is directly related to the normal use of production equipment and operating efficiency. If the cooling capacity is too small, the ideal cooling effect cannot be achieved, and the production efficiency is reduced, the operating energy consumption is increased, and the production equipment cannot normal operation so that the production line is shut down.
- However, if the selection is too large, the energy is wasted and the operating cost is also increased. The higher the cooling capacity of the chiller, the higher the price of the screw chiller. Therefore, the matching of the cooling capacity is very important for selecting a suitable screw chiller.
- Chilled water flow rate
The amount of chilled water is the ice water cooled by the screw chiller, which acts directly on the cooled part, but because of the water flow, it will directly affect the heat transfer effect.
- This flow rate is based on the material, density, and heat transfer ratio of the part to be cooled. Calculated, and some equipment is required to cool the flow because the amount of water is not enough to cool down. Therefore, the water flow is directly related to the operation of the screw chiller and the cooling effect of the production equipment.
- Inlet and outlet water temperature
When the production equipment or the production raw materials are in production and processing, when cooling is required, there is a temperature difference between the inlet and outlet of the chiller connected to the production equipment.
- This temperature difference is the actual heat generated by the production equipment so that it can be quite accurate. Calculate and select the right screw chiller.
- Understand the volume, weight, specific heat, and density of the equipment parts being cooled or the raw materials for production and processing.
This can quickly and efficiently calculate the cooling capacity of the required screw chiller. Also note the time required for the initial temperature of the cooled material to drop to the target temperature, which is also the way to calculate the cooling capacity. There is also a clear understanding of the highest and lowest temperatures required or affordable for the production equipment or materials to avoid impact on equipment or materials.
- What is the cooling medium?
The cooling medium generally includes tap water, ethylene glycol solution, oils and fats, seawater, food and beverage, and so on.
- Air-cooled screw chiller or water-cooled screw chiller?
Although the air-cooled screw chiller and the water-cooled screw chiller are both screw chillers, the cooling method of the screw chiller itself is different, so the installation method is different.
- The air-cooled screw chiller is more convenient, and the water pipe and the power supply can be operated, but the cooling effect is slightly worse than that of the water-cooled screw chiller, because the air-cooled screw chiller is cooled by air, and the air is greatly affected by the ambient temperature.
- The group installation location also requires space around the screw chiller.
- The water-cooled screwchiller is cooled by its use of water, so the name is a water-cooled screw chiller. The water-cooled screw chiller needs to be installed with a cooling tower to cool the unit. In the pipeline project, there are two more water pipes than the air-cooled screw chiller, but the effect of a water-cooled screw chiller is much better than that of an air-cooled screw chiller
- Even in the selection, water-cooled screw chiller is a smaller size than the air-cooled screw chiller
- . Therefore, under the installation conditions, most users will choose the water-cooled screw chiller over the air-cooled screw chiller.
You can refer to the above points to size a correct screw chiller for your business.
Select a suitable screw chiller for your industry is very important, besides the above information, there are also some other useful tips for your reference:
1. The main control parameters of the screw chiller are the refrigeration performance coefficient, rated cooling capacity, input power, and refrigerant type.
2. The selection of the screw chiller should be considered according to the cooling load and use. For refrigeration systems with long periods of low load operation, a multi-head piston compressor unit or a screw compressor unit should be used for easy adjustment and energy saving.
3. When selecting a screw chiller, priority is given to units with a higher coefficient of performance values. According to statistics, the average screw chiller operating time under 100% load is about 1/4 of the total running time.
The operating time ratios of 100%, 75%, 50%, and 25% of the total operating time were approximately 2.3%, 41.5%, 46.1%, and 10.1%.
Therefore, when selecting a screw chiller, priority should be given to models with a flatter efficiency curve.
At the same time, the adjustment range of the screw chiller load should be considered when designing and selecting. The multi-head screw chiller has excellent partial load performance and can be selected according to actual conditions.
4. When selecting a screw chiller, pay attention to the conditions of the nominal working condition. The actual cooling capacity of a chiller is related to the following factors:
a) cold water effluent temperature and flow rate;
b) Inlet water temperature, flow rate, and fouling coefficient of cooling water.
5. When selecting a screw chiller, pay attention to the normal working range of the unit, mainly because the current limit of the main motor is the current value of the shaft power under nominal conditions.
6. In the design selection, screw chillers should be noted that under nominal operating conditions, the outlet temperature of cold water should not exceed 15 °C, and the outdoor dry bulb temperature of air-cooled screw units should not exceed 43 °C.
If it is necessary to exceed the above range, it should be understood whether the range of use of the compressor is allowed and whether the power of the main motor is sufficient.
There is another important tip for using a screw chiller- the refrigeration oil or lubrication oil for screw compressors.
Why does the screw compressor need refrigeration oil or lubrication oil?
Refrigerated oil plays a very important role in the operation of the screw chiller refrigeration system.
Purpose of using refrigeration oil or lubrication oil:
1, Reduce Friction
The injection of lubricating oil forms an oil film on each friction surface of the screw compressor, which reduces friction and reduces energy consumption.
2, Take Away Frictional Heat
Injecting lubricating oil can take away frictional heat, keep the temperature of the moving pair within a reasonable range, and also take away various mechanical impurities to prevent rust and cleaning.
3, Reduce Leakage
Filling the friction surface gap with lubricating oil can seal the friction surface of the refrigeration compressor
Classifications of refrigeration oil or lubrication oil:
1. Natural mineral oil (referred to as mineral oil)
Mineral oil is a lubricating oil extracted from petroleum. It can only be dissolved with weakly polar or non-polar refrigerants;
Mineral oil is divided into four varieties: L-DRA/A, L-DRA/B, L-DRB/A, and L-DRB/B;
2, synthetic oil (referred to as synthetic oil)
Synthetic oil makes up for the shortage of mineral oil, usually has strong polarity, and can be dissolved in a more polar refrigerant (such as R134a);
3. There are two main types of synthetic oils.
Polyester oil: Multi-polyester (POE) oil has a better comprehensive performance
Polyether oil: Epoxy acetylene-propylene oxide polyether (PAG) has a better comprehensive performance
Why TopChiller can be your reliable screw chiller supplier?
TopChiller is a professional screw chiller manufacturer with decades years of experience.
We have installed thousands of various screw chillers in Singapore, Australia, Indonesia, Nigeria, Saudi Arabia, Kuwait for different industrial and commercial applications.
We also have an after-sales team that can do installation and commission at the screw chiller project site.
After installation, our engineer will give your staff a full detailed training on how to use the screw chiller and maintenance guide.
Common fault analysis of screw chillers
For the use of screw chillers, some common fault problems include high voltage fault, low voltage fault, low valve temperature fault, compressor overheat fault, communication fault, etc.,
But to effectively solve these fault problems, you must first link the main working principle of the screw chiller, and among them, the four processes of the refrigeration cycle, after the adiabatic compression of the compressor, becomes a high temperature and high-pressure state.
The compressed gas refrigerant is condensed by isostatic cooling in a condenser, and after condensation, it is changed into a liquid refrigerant, and then expanded to low pressure through a throttle valve to become a gas-liquid mixture.
The liquid refrigerant under low temperature and low pressure absorbs the heat of the cold matter in the evaporator and becomes a gaseous refrigerant again.
The gaseous refrigerant re-enters the compressor through the pipeline and begins a new cycle.
After understanding the main working principle of the screw chiller, the common faults of the screw chiller are analyzed below.
1. High-Pressure Alarm
The compressor discharge pressure is too high, causing the high voltage protection relay to operate. The screw compressor from chiller discharge pressure reflects the condensing pressure.
The normal value should be 1.40~1.60MPa, and the protection value should be set to 2.00MPa.
If the long-term pressure is too high, it will lead to an excessive operating current of the compressor, easy to burn the motor, and easily cause damage to the valve port of the compressor exhaust port.
What should be done is to control the discharge pressure of the compressor in a safe range.
2. Low-pressure alarm
The screw compressor suction pressure is too low, causing the low voltage protection relay to operate. The suction pressure of the compressor reflects the evaporation pressure.
The normal value should be 0.40~0.60MPa, and the protection value should be set to 0.20MPa. If the suction pressure is low, the amount of return air is small, the cooling capacity is insufficient, and the electric energy is wasted.
The heat of the compressor motor for return air cooling is poor, and the motor is easily damaged! The solution is the same as the high-pressure fault, try to keep the compressor within the normal pressure range.
3. Low valve temperature error
The outlet temperature of the expansion valve reflects the evaporation temperature, which is a factor affecting the heat exchange.
Generally, it has a temperature difference of 5.0 to 6.0 °C from the outlet water of the refrigerant water. When a low valve temperature fault occurs, the compressor will stop.
When the valve temperature rises, it will automatically resume operation with a protection value of -2.0 °C.
4. Compressor overheat fault
A thermistor is embedded in the winding of the compressor motor, and the resistance is generally 1kΩ. When the winding is overheated, the resistance value will increase rapidly.
When the winding exceeds 141kΩ, the thermal protection module SSM will act to cut off the unit operation and display the overheat fault. The TH fault indicator lights.
5. Communication failure
The control of each module by the computer controller is realized through the communication line and the total interface board.
The main cause of the communication failure is the poor contact or open circuit of the communication line, especially the interface is affected by moisture oxidation, and the unit electronic board or the total interface.
If the board is faulty, the address dial switch is improperly selected, and the power failure can cause a communication failure.
The above five kinds of fault phenomena are the most common, and understanding these fault phenomena and judgment ability and solution has an irreplaceable effect on extending the service life of the screw chiller.
Besides the above, we must point the screw compressor out. Because the screw compressor is the key refrigeration part for a screw chiller.
The screw compressor has the characteristics of small size, lightweight, and easy maintenance, and is a type of development that is faster in refrigeration compressors.
On the one hand, the screw line and structural design have made great progress.
On the other hand, the introduction of special milling machines for screw rotors, especially grinding machines, has improved the machining accuracy and machining efficiency of these key components, and the performance of screw compressors has been effectively improved.
Due to the continuous improvement of the working reliability of the screw compressor, it has gradually replaced the reciprocating compressor in the medium cooling capacity range and occupied part of the market of centrifugal compressors.
In operation, there are a lot of operational details to be aware of to ensure the smooth and efficient operation of the equipment and improve production efficiency.
Screw compressor can’t be running
First check if the power supply wiring of the compressor is correct, whether the power switch is properly closed, whether the power fuse is blown, and whether the power supply voltage reaches 90% or more of the rated voltage.
Check the compressor’s pressure relay components for damage and pressure regulator settings.
Poor contact of the start button, this situation is less common, because the current screw compressor, unless it is cheap to buy a very low-cost machine, it is generally not a problem, even if it is solved, it is very simple.
At the time of starting, the pressure of the outlet switch and the outlet is not set too high, the switch of the electrical circuit is not restored, and the setting of voltage and current is unreasonable.
The general screw compressors have automatic protection devices, so when some parts of them fail, they cannot be started normally. Start and stop the control loop.
Because there are many electrical components, there are more control points and the failure rate is relatively high. Start button, stop button or switch, etc., may cause the host to fail to start or stop due to improper operation.
Such as the start button, stop button, emergency stop button, control panel, etc., excessive force during operation may cause the button to be stuck on the edge of the button housing and cannot be reset.
Screw chiller failure:
Mainly including compressor motor failure, rotor lock, and so on.
When the compressor is overloaded for a long time, it will form a rotor tooth surface and the bearing fatigue damage will be stuck; the compressor lubricating oil pipeline will be blocked to form a lack of oil, causing the anode and the anode and the bearing temperature to be too high and damaged and locked.
If the bearing and the male and female rotors are disassembled when repairing the compressor, the installation is not cautious and the installation accuracy is not up to the requirement. The anode and the anode are not parallel and the male and female rotors cannot be rolled.
In addition, when the compressor is repaired improperly, an external solution is applied to the rotor, and the axial and radial gaps between the female and male rotors are changed so that they cannot rotate.
Under normal circumstances, the manufacturer has set parameters such as lubricant level, oil pressure, and filter pressure difference on the compressor control system.
If the above conditions occur, it will stop actively to protect the compressor.
However, some users tend to increase the set parameters or short-circuit certain alarm lines and pipelines for convenience and save money, causing the equipment to leave the monitoring and causing the failure.
Generally, the probability of motor failure in the compressor is relatively low, but if it occurs, it will be more troublesome, and it needs to be excluded and repaired by professionals.
Screw Compressor Exhaust pressure is too low
Under normal circumstances, the in-service compressor can eliminate the exhaust pressure caused by the high altitude, but can not ignore the increase in gas consumption.
If there is no large leak point in the compressed airline, it is a problem with the compressor unit itself. We can check if there are any problems with the following aspects:
1. Is your screw chiller maintenance timely?
The displacement of the compressor drops. First, see if the compressor has been serviced? Many times, the displacement of the compressor drops, there is no big problem, that is, the customer is neglected to maintain.
If the working environment is not ideal, the compressor air filter is easy to block. Lighter can use dust to remove dust; blockage is serious, need to replace the new air filter.
2. Are the intake valves all open?
The compressor discharge is reduced, check the unit, if just maintenance, remove the three filters and oil problems, then first check the compressor intake valve.
Remove the air intake hose, turn on the compressor, and see if the opening of the intake valve is normal. The theoretical design life of the intake valve is 100,000 times.
Because each manufacturer uses different brand batches, the quality is also different. Therefore, the failure of the intake valve may cause the unit to reduce the exhaust volume.
If the intake valve cannot be fully opened when the compressor is loaded, it can be concluded that the exhaust gas volume is a failure of the intake valve and should be removed for repair or replacement.
3. Motor failure
After the intake valve failure is removed, if the screw chiller exhaust volume has not changed, consider whether the motor is faulty.
Due to a local short circuit in the motor coil, or bearing wear, the motor shaft wears, causing the motor speed to be lower than the rated speed, causing the compressor to discharge.
The motor coil, bearing, etc. should be repaired, and the compressor displacement should be tested after repair…
Closer to this principle is the belt-driven compressor, which should take into account the belt load and the intact state.
Sometimes the belt speed is insufficient due to the slip or slack of the belt, resulting in low exhaust pressure.
4. Pressure switch setting working pressure is too low
This kind of situation is often caused by changes in working conditions, or after the system has been adjusted, overhauled, etc., the system parameters are moved.
Otherwise, under normal circumstances, the working pressure will not be easily mishandled after being set.
Screw Compressor parameter setting is not recommended by the user at will but should be combined with the equipment supplier and the user to comprehensively consider the working conditions and equipment operating characteristics, and set a reasonable value.
Compressor Exhaust oil content is too high
For companies that are very concerned about air quality, the air must contain too much oil. There are many reasons for this problem, mainly due to the following reasons:
first, the oil level is too high;
second, the return pipe filter or orifice is blocked;
the third is that the oil and gas separation core is damaged.
The fourth is that the gas pressure of the compressor is too low; then the minimum pressure valve fails; the last is the problem of the lubricant itself.
If too much foam is used, it will also increase the oil content of the gas.
1. Too much cooling oil added to the compressor
An excessive amount of lubricating oil is added, which exceeds the allowable range.
Although the separation system separates the oil and gas during the operation of the compressor, in the discharge of the gas, the gas also entrains the cooling oil into the gas, causing the discharge. The oil content in the gas is too high.
2. The return line is faulty
In the working process of the screw compressor, the oil return pipeline shoulders an important responsibility.
The oil separation inside and the compressor inlet will form a pressure difference. Under this pressure difference, the oil return pipeline is responsible for the oil separator.
The oil collected at the bottom is sent back to the compressor and continues to be used during the next compression cycle.
If there is a fault such as a blockage, breakage, and incorrect installation on the return line, the oil collected at the bottom of the oil separator cannot be sent back to the compressor, causing too much oil to accumulate at the bottom, and this part of the oil that is not sent back to the compressor is As the gas is discharged, there is a phenomenon of oil in the exhaust process.
3. Oil separation core is damaged
During the operation of the screw compressor, if the oil separation core is damaged, such as damage or perforation, it loses the role of oil and gas separation.
That is to say, the exhaust gas of the mixed gas and the compressor is directly penetrated, and a large amount of cooling oil is not separated, and as the gas is discharged together with the body, an oil failure occurs during the exhausting process.
4. Screw chiller system pressure control is too low
If the system pressure control is too low, the centrifugal force in the separator will be less than the centrifugal force required for the work, then the function of the separator will not be fully reflected, resulting in the oil content in the separator entering the next step is too high, beyond its separation range.
As a result, the oil and gas separation is not complete, and oil failure occurs during the compressor exhaust process.
5. Minimum pressure valve failure
During the operation of the screw compressor, the function of the minimum pressure valve is to ensure that the system pressure is controlled above the minimum pressure during operation.
If the minimum pressure valve fails, the minimum pressure of the system will not be guaranteed. Since the gas consumption of the luck equipment is very large, the system pressure is too low, and the oil return pipeline cannot return oil.
The oil that collects at the bottom of the oil separator will not be returned to the compressor and will expel the compressor with the compressed gas, causing oil failure during the exhaust process.
6. The quality of the cooling oil is unqualified
If the compressor is added with a relatively poor defoaming lubricant, or the ambient air humidity is high, the water leakage at the bottom of the lubricating oil station will cause the lubricating oil to foam, causing the oil content in the exhaust gas to increase.
Compressor Exhaust temperature is too high
Mechanical failures include:
a. oil stop valve failure;
b. compressor oil filter failure;
c. thermal control valve (temperature control valve) malfunction;
d. compressor oil regulator abnormal;
e. compressor oil cooler Abnormal (this fault is common in water-cooled compressors);
f. Compressor head failure, including poor lubrication and unreasonable design of the machine itself, installation is not necessary;
g. air filter failure; h. oil and gas separator failure; i. Temperature sensor and computer failure, abnormal reading.
The effects of compressor oil include:
a. insufficient compressor oil;
b. deterioration of compressor oil, poor fluidity of oil, reduced heat exchange capacity;
c. improper selection of compressor oil viscosity;
d. The quality is not good: the thermal oxidation performance is poor, the viscosity-temperature performance is poor, and the air separation ability is poor.
The screw compressor cannot be unloaded
Loading and unloading are the basic functions of the compressor. They cannot be loaded and unloaded, and the compressor is useless.
Because if it can’t be loaded, the compressor has no compressed air output; if it can’t be unloaded, after there is no compressed air demand downstream, it can be imagined as: “The consequence of constantly inflating a balloon.”
When the compressor exceeds the rated pressure during operation, it will continue to load and run, and the maximum pressure value will be set to cause the screw compressor to trip or the safety valve will act.
If the actual air consumption of the production is not greater than the gas volume of the compressor unit and a large amount of leakage of the pipeline, the compressor may not be unloaded mainly for the following reasons:
a. If the pressure switch is set improperly or after setting, there will be elegant and false, and the false number will be reported.
b. The intake valve is not working properly, the card is stuck, etc.;
c. When the system stops using the gas, the venting solenoid valve is invalid, and the performance state is the pressure slowly. Rise, not like loading up;
d. control loop failure;
e. loading solenoid valve failure, such as loading at the same time of unloading, and the loaded gas volume is greater than the unloading, so the pressure continues to increase.
In the current screw compressor design and production level, many of the problems with screw compressors are mostly caused by untimely maintenance or improper operation.
If we strictly abide by the screw chiller operation process and pay attention to screw chiller maintenance, then I believe that many unnecessary failures will not happen.
Selection points and troubleshooting of screw chillers
Screw chiller selection points
1. The main control parameters of the screw chiller are the refrigeration performance coefficient, rated cooling capacity, input power, and refrigerant type.
2. The selection of screw chillers should be considered according to the cooling load and use. For refrigeration systems with long periods of low load operation, a multi-head piston compressor unit or a screw compressor unit should be used for easy adjustment and energy saving.
3. When selecting a screw chiller, priority is given to units with higher performance coefficient values.
According to statistics, the average screw chiller operating time under 100% load is about 1/4 of the total running time. 100%, 75%, 50%, 25% of the total running time
The operating time ratio of the load is approximately 2.3%, 41.5%, 46.1%, and 10.1%. Therefore, when selecting a correct screw chiller, priority should be given to models with a flatter efficiency curve.
At the same time, the adjustment range of the screw chiller load should be considered when designing and selecting.
The multi-head screw chiller has excellent partial load performance and can be selected according to actual conditions.
4. When selecting a suitable screw chiller, pay attention to the conditions of the nominal working condition. The actual cooling capacity of a chiller is related to the following factors:
a) cold water effluent temperature and flow rate;
b) Inlet water temperature, flow rate, and fouling coefficient of cooling water.
5. When selecting a proper screw chiller, pay attention to the normal working range of the model unit, mainly because the current limit of the main motor is the current value of the shaft power under nominal conditions.
6. In the design selection, it should be noted that under the nominal working condition flow, the outlet temperature of cold water should not exceed 15 °C, and the outdoor dry bulb temperature of the air-cooled unit should not exceed 43 °C.
If it is necessary to exceed the above range, the compressor should be known. Whether the range of use is allowed, and whether the power of the main motor is sufficient.
The control of each module by the computer controller is realized through the communication line and the total interface board.
The main cause of the communication failure is the poor contact or open circuit of the communication line, especially the interface is affected by moisture oxidation, and the unit electronic board or the total interface If the board is faulty, the address dial switch is improperly selected, and the power failure can cause a communication failure.
Causes and treatment of abnormal vibration of the screw chiller unit?
- The screw chiller anchor bolts are not tightened or loose; tighten the anchor bolts.
- The screw compressor shaft and the motor shaft are misaligned or dissimilar; re-align.
- The vibration of the pipeline causes the vibration of the unit to increase; add support points or change the support points.
- The screw compressor draws in too much oil or refrigerant liquid; when it stops, the disk drives the liquid out of the compressor.
- The spool valve should not stop at the required position, but vibrate there; check the oil piston, the four-way valve, or the increase/decrease solenoid valve for leaks and repairs.
- The vacuum in the suction chamber is too high; open the suction shut-off valve and check if the suction filter is blocked.
The reasons for the insufficient cooling capacity of the screw chiller and the treatment methods?
- The position of the spool valve is not suitable or other faults (the spool valve cannot be attached to the fixed end); check the position of the indicator or angular displacement sensor and check the spool valve.
- The suction filter is clogged, the suction pressure loss is too large, the suction pressure is decreased, and the volumetric efficiency is lowered; the suction filter is removed and cleaned.
- The screw chiller is not properly worn, causing excessive clearance; checking, adjusting, or replacing parts.
- The resistance loss of the suction line is too large, and the suction pressure is much lower than the evaporation pressure; check the suction shutoff valve and the suction check valve to find the problem for repair.
- Refrigerant Leakage between high and low-pressure systems; check the driving, parking bypass valve, and return valve, and find problems for repair.
- The injection quantity of refrigerant is insufficient, and the sealing effect cannot be achieved; check the oil circuit, oil pump, and oil filter to increase the fuel injection amount.
- The exhaust pressure is much higher than the condensing pressure, and the volumetric efficiency is lowered; check the exhaust system piping and valves to remove the resistance of the exhaust system. If the system seeps into the air, it should be discharged.
Reasons for the abnormal sound of the screw chiller during operation and treatment
- There is debris in the rotor tooth groove; the rotor and the suction filter are inspected.
- Damage to the thrust bearing; replace the thrust bearing.
- The main bearing is worn, the rotor is rubbed against the body; the main bearing is repaired and replaced.
- The spool is deflected; the slide guide block and the guidepost are inspected.
- Loose joints of moving parts; disassemble the machine for maintenance and strengthen the relaxation measures.
Causes and treatment of screw chiller exhaust temperature or oil temperature drop?
- Inhalation of wet steam or liquid refrigerant; reducing the amount of liquid supplied to the evaporation system.
- Continuous no-load operation; check the spool valve.
- The exhaust pressure is abnormally low; the water supply is reduced or the number of condenser inputs is reduced.
The reason for and treatment of the screw chiller slide valve movement are not flexible or not working?
- The four-way reversing valve or solenoid valve is not flexible; check the four-way reversing valve or solenoid valve coil and wiring.
- The oil pipeline system is blocked; overhaul.
- The oil piston is stuck or leaking; repair the oil piston or replace the seal.
- The oil pressure is too low; overhaul and adjust the oil pressure.
- The slide valve or guide key is stuck; overhaul.
The reason for and treatment of the screw compressor body temperature are too high?
- The moving parts are abnormally worn; the compressor is repaired and the damaged parts are replaced.
- Inspiratory severe overheating; reduce inhalation superheat.
- Leakage in the bypass line; check whether the driving or parking bypass valve leaks.
- The compression ratio is too large; detecting the suction and exhaust pressures and reducing the pressure ratio
Why is the compressor reversing when the screw compressor is stopped?
- The suction and exhaust check valves are not closed tightly; overhaul and eliminate the jamming of the valve plate.
- Prevent the reversed bypass line valve from opening in time; check and repair.
How to arrange large, medium, and small repairs or maintenance of screw chillers?
- The motor of screw compressor: disassembly, overhaul, and replacement, bearing refueling, a period of 2 years, refer to the motor use manual.
- Coupling: Check the coaxial between the compressor and the motor (check whether the elastic transmission piece is damaged or the rubber pin is worn) for 3-6 months.
- Oil separator: clean the interior for 2 years.
- Oil cooler: remove scale (water-cooled) and grease stains for six months; depending on the water quality and dirt.
- Oil pump: trial and error repair, the period is 1 year.
- The oil filter (including crude oil filter), suction filter: cleaning, a period of six months. It should be cleaned for the first time driving for 100-150 hours.
- Oil pressure regulating valve: Checking capacity check, the period is 1 year.
- Sliding valve: action check, the period is 3-6 months.
- Safety valve, pressure gauge, thermometer: calibration, the term is 1 year.
- Safety valve, pressure gauge, thermometer: calibration, the term is 1 year.
- Pressure relay, temperature relay: Verification, the term is about half a year. See the instructions.
- Electrical equipment: Action check, the period is about 3 months. See the instructions.
- Automatic protection and automatic control system: the period is about 3 months.
Installation and commissioning of screw chiller
Preparation before the starting of the screw chiller:
The correct commissioning of the screw chiller is an important part of ensuring the normal operation of your screw chiller, saving energy and prolonging the service life.
For on-site installation of large and medium-sized screw chiller, the requirements should be familiar with the layout and connection of the entire system, the outline structure and component performance of each equipment, as well as the electronic control system and water supply system.
To this end, engineers such as refrigeration and hydropower should participate in the commissioning.
Users should carefully read the operation manual of the screw chiller provided by the factory before commissioning, and proceed step by step according to the operation requirements.
The operator must undergo special training from the factory to obtain the operation certificate of the screw chiller before the operation can be carried out, to avoid fatal damage to the screw chiller unit caused by the wrong operation.
A Preparation before screw chiller commissioning
(1) Since the screw chiller is medium and large, it is necessary to closely cooperate with the design, installation, and use during commissioning.
To ensure that the commissioning work is carried out in an orderly manner, the relevant personnel must form a temporary commissioning team to fully conduct the commissioning work.
(2) The personnel responsible for commissioning should be fully familiar with the structure and performance of the screw chiller, familiar with the safety technology of the screw chiller, clarify the methods, steps and technical requirements to be debugged, formulate detailed and specific commissioning plans and make each post the commissioning staff clarifies their tasks and requirements.
(3) Check whether the installation of the screw chiller meets the technical requirements, whether the foundation of the screw chiller meets the requirements, and whether the size, specification, and material of the connecting pipeline meet the design requirements.
(4) The power supply system of the screw chiller should be fully installed and commissioned.
(5) Pass the water test on the cold water and cooling water system separately, flush the dirt of the waterway system, the water pump should work normally, and the circulating water volume meets the requirements of working conditions.
(6) Clean and debug the environmental site to achieve clean, bright, and smooth.
(7) Prepare the various common and specialized tools required for commissioning.
(8) Prepare various measuring instruments and meters for pressure, temperature, flow, quality, time, etc. required for commissioning.
(9) Prepare the safety protection equipment necessary for commissioning operation.
B screw chiller commissioning
(1) Charge of refrigerant.
At present, the screw chiller is generally filled with refrigerant before leaving the factory.
After the installation on-site, if no accidental damage is found in the visual inspection, the relevant valve can be opened directly (you should read the manufacturer’s instruction manual first, in transit, on the unit).
The valve is normally in the off state for commissioning.
If the refrigerant has been leaked or insufficient, first find the leak point and eliminate the leak, then add the required grade of refrigerant according to the product instruction manual.
Note that the refrigerant charge should meet the technical requirements.
(2) Some users are charged with refrigerant on site, and the refrigerant charge and refrigerant grade must be following regulations.
The refrigerant charge is insufficient. This Will result in insufficient cooling.
An excessive refrigerant charge will not only increase the cost but also adversely affect the operating energy consumption.
(3) Before charging the refrigerant, sufficient refrigerant should be prepared in advance. When filling, it can be directly charged from the special filling valve.
Since the system is in a vacuum state, the pressure difference between the refrigerant and the system in the cylinder is large.
When the valve is opened (the air in the connecting pipe should be blown out with the refrigerant first, so that the air does not enter the screw chiller unit and affect the performance of the unit), the refrigerant is quickly replaced by the cylinder.
In the flow system, after filling, the liquid filling valve should be closed first, and then the connecting pipe should be removed.
Screw chiller starting up and operation
- Check the oil level and oil temperature of each screw compressor: the oil level is 1/3~2/3; the oil temperature is 50°C～60°C, and the hand heater should be hot.
- Check the main power supply voltage and current: the power supply voltage is in the range of 340V ~ 480V; the three-phase voltage unbalance value <2% (> 2% absolutely can not be turned on); the three-phase current unbalance value <10%.
- Dynamic chilled water pump and cooling water pump: After the circulation of the two water systems is established, adjust the opening of the evaporator and condenser inlet and outlet valves.
- Check the chilled water supply temperature: Whether the set value is suitable or not, it can be changed.
- Check before the screw chiller starts: Check the tightness of the electrical joint (main circuit, control circuit), at least the oil tank should be heated for 24 hours so that the oil tank temperature can not be lower than 38 degrees.
- Check before the screw chiller starts: Check the status of each valve of the screw chiller unit, water pump, pressure gauge, thermometer, filter, etc.
- Check before the screw chiller starts: Check the end of the whole screw chiller unit. Check the condition of the cooling tower if you are operating the water-cooled screw chiller.
- Check before the screw chiller starts: firstly open the chilled water pump and cooling water pump of the water system to check whether the water system is running normally, ensure that the gas is not entrained, and ensure that the water pressure drop of the water system is within the required range.
Monitoring and adjustment of screw chiller operation
For screw chillers, the following should be mainly concerned during operation:
1. The temperature and pressure of the chilled water inlet and outlet of the evaporator.
2. The temperature and pressure of the condenser cooling water inlet and outlet.
3. The pressure and temperature of the refrigerant in the evaporator.
4. The pressure and temperature of the refrigerant in the condenser.
5. Electrical current and voltage of the main motor.
6. The pressure and temperature of the lubricant.
7. Is your screw chiller running smoothly, is there any abnormal noise?
8. Whether the valves of the screw chiller have leaks.
9. Is the joint with each water pipe tight?
From the above, the most important is the Danfoss expansion valve adjustment.
Here are some tips for you on how to adjust the thermal expansion valve of your screw chillers:
1. The evaporator outlet should use the thermometer to measure the temperature or look at the suction pressure to check the superheat.
2. Danfoss expansion valve adjustment superheat is too small (supply volume is too large), the adjustment rod should be rotated clockwise half a circle or a circle (ie increase the spring force, reduce the valve opening), increase the degree of superheat, so that Reduced refrigerant flow;
The number of turns of the adjusting rod thread at one time should not be too much (the adjusting rod thread rotates one turn, and the superheat degree changes about 1-2°).
For the same reason, reduce the superheat degree counterclockwise and increase the cooling capacity.
3. Danfoss expansion valve adjustment experience:
Turn the adjusting rod thread to change the opening of the valve so that the evaporator can just be frosted or dew on the outside of the return pipe.
For a screw chiller with an evaporation temperature lower than 0 degrees, if it is touched by hand after frosting, there is a feeling of coldness that sticks the hand, and the opening degree is appropriate; for the evaporation temperature above 0 degrees, the condensation is visible. The judgment of the situation.
4. The correct commissioning of the Danfoss expansion valve directly affects the cooling effect and energy saving of the cold storage.
The cooling of the cold storage is slow, mostly the improper adjustment of the Danfoss expansion valve.
According to the thermal properties of the refrigerant, the lower the pressure, the lower the corresponding temperature; the higher the pressure, the higher the corresponding temperature. Among them, the adjustment of the Danfoss expansion valve is the most critical.
The opening degree of the Danfoss expansion valve is small, the flow rate of the refrigerant is low, and the pressure is low; the opening degree of the Danfoss expansion valve is large, the flow rate of the refrigerant is high, and the pressure is high.
If the expansion valve outlet pressure is too low, the corresponding evaporation pressure and temperature are too low.
However, due to the decrease in the flow rate into the evaporator, the pressure is reduced, the evaporation rate is slowed down, the cooling capacity per unit volume (time) is decreased, and the cooling efficiency is lowered.
Conversely, if the expansion valve outlet pressure is too high, the corresponding evaporation pressure and temperature are too high.
The flow rate and pressure entering the evaporator are increased.
Because the liquid evaporates excessively, the excessive moisture (or even liquid) is sucked by the compressor, causing the wet stroke (liquid blow) of the compressor, causing the compressor to fail to work normally, resulting in a series of work.
Bad conditions, even damage the screw compressor for your screw chiller.
Therefore, the opening degree of the expansion valve should be adjusted according to the current water temperature, that is, adjusted under the pressure corresponding to the water temperature.
The expansion valve must be carefully and patiently adjusted. The pressure must be transferred to the pressure gauge after passing through the evaporator to the water temperature for boiling exchange (evaporation) and then entering the compressor suction chamber through the pipeline. It takes time.
Each time the expansion valve is mobilized, it usually takes 10~15 minutes to stabilize the adjustment pressure of the expansion valve on the suction pressure gauge, and the adjustment cannot be rushed.
The suction pressure of the compressor is the main parameter for adjusting the pressure of the expansion valve.
It is usually prone to failures such as clogging of the filter, leakage of the temperature-sensitive agent, and the like.
The adjustment reaction is not sensitive, the adjustment is out of control or cannot be adjusted.
When the frost is formed at the inlet of the expansion valve (or the valve cover is also frosted), the temperature of the inlet pipe is lower than normal temperature, or even condensation;
The suction pressure of the compressor is lower than the corresponding pressure at the storage temperature, the screw chiller operating temperature and the exhaust temperature is high.
And the cooling temperature drops slowly or can not be lowered, mostly due to the filter plugging of the expansion valve or the dirty plugging failure.
As a leader in screw chiller manufacturing, TopChiller has 20 years of experience in design and making screw chillers.
We have a complete of screw chiller models and cooling capacity from 50Ton to 100Ton-150Ton-200Ton can even up to 300Ton and 500Ton Max.
Both air-cooled screw chiller and water-cooled screw chiller manufactured by TopChiller are featuring precision workmanship, compact design, and high cooling efficiency.
All the refrigeration major components from screw chiller designed by TopChiller are world-first refrigeration brands.
We are willing to provide technical support to all clients, we have both standard and custom designs in air-cooled screw chillers and water-cooled screw chillers.
If you are looking for a reliable screw chiller manufacturer?
If you are searching for a high-quality screw chiller for your business?
Contact our refrigeration engineering to help you get a suitable screw chiller design and solution.
Screw Chiller-The Ultimate FAQ Guide by TopChiller
Screw Chiller is the most valuable equipment for industrial application. It is very effective in providing cooling for large Industrial applications.
The rapid increase in Industrialization needs a proper mechanism to run.
When you are seeking a Screw Chiller, You are not only providing a cooling agent to your application but also increasing its efficiency of production.
The Screw Chiller is well equipped with components that help it to run smoothly. It has a decent fabricated quality which shields it from being harmed by the external climate.
It has cost-efficient nature which saves your money and time.
This guide includes every possible piece of information about Screw Chiller to help you select one.
- What is Screw Chiller?
- What are the Features of the Screw Chiller?
- What are the Main Components of a Screw Chiller?
- Is Screw Chiller Cost-Efficient?
- Why do you need a Screw Chiller for your Application?
- What are the Advantages of a Screw Chiller For your Application?
- What is the Difference Between Screw Chiller and Centrifugal Chiller?
- What is the Working Principle of a Screw Chiller?
- How to Select Right Screw Chiller for Your Application?
- How to Size Screw Chiller for Your Application?
- How to Install the Screw Chiller Using Some Tips?
- How to Maintain the Screw Chiller?
- How to Troubleshoot Problems with Your Screw Chiller?
- FAQ of Screw Chiller
1. What is Screw Chiller?
Screw Chiller is an effective heat-removing source that provides cooling solutions to the industrial process and other essential applications.
Providing efficiency and using less power are the core features of a Screw Chiller.
The Screw Chiller uses the two spinning helical screws that provide the required pressure to start the vapor compression refrigerant process.
Due to the presence of a Screw Compressor, it is called Screw Chiller
The refrigerant involves the cooling of the Solution or water.
For safety, it has a high and low voltage protector in case of any sudden increase and decrease in Voltage.
It consists of soundproof because it contains limited parts, which reduces overall sound production. It has a compact structure and is lightweight.
The cool water is circulating the application with the help of a Screw Chiller to keep the application cool.
After Circulating cool water in the application, it becomes hot. After that, the all-over heat is accumulated from the application in Screw Chiller and exited in the atmosphere.
The Screw Chiller is made up of a 50 centigrade environment. The centigrade varies from size to size.
The Size starts from 175 KW t0 1575 KW.
There are also other options of cooling but these are inefficient and cost a lot. The Screw Chiller is manufactured by experts to meet the needs with quality standards at a low cost.
Due to its quality standard, Screw Chiller keeps working 24 hours without the delay and getting heated up.
Screw Chiller Designed by TopChiller
2. What are the features of the Screw Chiller?
The Screw Chiller is equipped with various features mentioned below.
The evaporator and condenser in it are installed inside the Screw Chiller which saves additional space.
The other machines need a specified foundation for stability as these to vibrate a lot.
Due to the compact size and stability, the Screw Chiller produces a very low amount of vibration. So it can be placed on a normal foundation.
In a high-rise building, the cost of the pump lift reduces to a great extent.
The highest ambient temperature is 50 Centigrade, this decreases its failure on summer days.
As mentioned above the Screw Chiller has few parts so, it takes less time to be installed as compared to its alternative.
The Screw Chiller is equipped with many features like simple design, flexible adjustment, fewer wearing parts, and it has a low failure rate.
The Screw Chiller has no suction and exhaust valve. Suction is a negative difference in the pressure produced among two points which change either liquid or gas from higher pressure to lower pressure.
When the heat pump unit is working the pressure in working condition will be more. At that point, the Screw Chiller is a suitable system.
One of the key features is that it uses multiple refrigeration circuits.
Multiple compressors have a cycle control to start and stop which helps in balancing the load and increasing the load.
If any of the circuits are out of order and need maintenance, so another circuit of Screw Chiller normally works as a backup.
Screw Chiller is equipped with environmental protection and energy-saving features.
With the help of Artificial intelligence, it adjusts its capacity according to the need to save energy and save the environment from contaminating particles in heat.
3. What are the Main Components of a Screw Chiller?
There are four main components of the Screw Chiller are Compressor, evaporator, expansion valve, and controls.
Every system has the same components. However, they work differently in every system.
Screw Chiller has a unique compressor. Its compressor uses spiral rotators that help in compressing the gas.
The Compressor rotates the refrigerant from lower pressure to higher pressure. The compressor can provide a medium load for a medium application.
The compressor is situated in the stationary casing of the Screw Chiller.
The evaporator in Screw Chiller is considered a heat exchanger. The evaporator removes unnecessary heat from the liquid and exits the heat in the environment.
When the heat exits through evaporate the water becomes cool. The water then travels back to the application to provide cooling.
The Screw Chiller evaporator is often insulated. It is insulated because the cool water is expensive to produce.
If there will be no cover or insulation on the evaporator of the Screw Chiller then it might collect heat from the room where it is located instead of the plant.
In this way, the cool water will be heated again even without circulating in the application.
Insulating is covered to prevent unnecessary heating from the room.
The expansion valve has a very important role. This helps in controlling the flow of refrigerants to the refrigeration.
The expansion valve is used to change the liquid refrigerant with high pressure in the condenser to the gas refrigerant with low pressure in an evaporator.
In Screw Chiller the flow rate is controlled by an expansion valve to get the desired cooling load for application.
The Screw Chiller has the necessary controls. Like controlling its cooling capacity. Controlling the flow rate of the liquid.
It has a control system that indicates if there is any fault. It rings an alarm when anything in it goes wrong.
It has the feature of working on the set cooling temperature. You can set the required temperature on the control system.
Screw Chiller Unique Compressor
4. Is Screw Chiller Cost-Efficient?
Everyone wants a cost-efficient Screw Chiller. However, the initial investment might be expensive.
Although it is cost-efficient for the long term as you do not have to buy different individual systems. The applications already cost a lot.
The Screw Chiller in application reduces the power consumption cost up to 30%. It does not need a high power supply. It works in normal voltages too but power must be stable
The application might be the only thing in the plant that consumes more power and it is logical to seek the low-cost efficient Screw Chiller.
To analyze the actual cost efficiency you should consider two factors that affect the consumption of power.
The first factor is the load. The Screw Chiller work according to the load of the application. If the load of the application is high then it may consume high power.
The second factor that affects its power consumption is the temperature of water traveling to the condenser.
When the temperature of the water is high then the Screw Chiller has to work more effectively and it will require more energy, vice-versa.
The Screw chiller with the constant-speed compressor motor lowers the entering of water into the condenser by closing its promotional vanes which saves energy.
The speed of the Screw Chiller also increases and reduces costs.
However, lowering condenser water temperature also lowers the cost. The cost also depends on the size and working of your application.
If your application works 24/7 so as the Screw Chiller then you might expect more energy consumption.
5. Why do you Need a Screw Chiller for your Application?
Every application needs a cooling agent. More often it’s up to the consumer to choose a cooling system according to their needs.
It is mostly centralized which means one Screw Chiller serves to cool everywhere it needs. It consumes less power when it is centralized.
The other systems are decentralized, these works individually and may result in high power consumption.
It also brings down the temperature of the liquid in laboratories of nuclear facilities.
More often in during plastic production, the heat is produced in excess during injecting and molding process. It Works efficiently if there is any excess heat in the application.
If the heat is not removed at the required time your application will cease to work.
If you have any application related to food then Screw Chiller is a must for you. As it keeps, meat, dairy farm products, food packages, and beverages cool.
It has an effective mechanism and system. It is easy to use due to its user-friendly control system. It works quietly and does not produce an irritating sound.
However, instead of its user Friendly, the Screw Chiller must be operated under the supervision of a highly professional person.
There is a water-cooled Screw Chiller, these use cooling towers and send water according to needs.
The water-cooled Screw Chiller is perfect for indoor installation and where a source of water is convenient. It can work under a temperature of 50°C.
If the area is water scarce and it is harder to obtain water in high quantity. So, it is better to install an air-cooled Screw Chiller.
An air-cooled Screw Chiller is installed outdoor. As these release heat in the atmosphere.
Screw Chiller is Widely used for Nuclear Facilities
6. What are the Advantages of a Screw Chiller For your Application?
The increasing technologies have created a demand for advanced HVAC systems and powerful Screw Chiller.
Everyone seeks a bunch of advantages while selecting any HVAC system.
The Screw Chiller is the right choice for the most advanced applications. It has many benefits as mentioned below.
- The Screw Chiller is a system that requires a low space for installation. Its compressor is the only unit that is big and consumes space.
Its pipes and the transporter of water occupies less space.
It has very few electronic boxes and these do not consume more space.
- The working efficiency is very high. It provides the required amount of cooling that the application needs.
It does not over-cool the application as this affects the production.
Screw Chiller has the feature of adjusting load starting from the load like 100%, 75%, 50%, and 25%.
Its mechanism uses water as the source of coolant and has higher efficiency as compared to the water-cooled Screw chiller.
- Screw Chiller is equipped with the latest mechanism and compressor that does not allow it to cool the application.
This saves a colossal amount of energy and is not sensitive to wet stroke.
- The main source of cooling is water.
The water inside its Compressor reduces the vibration of the application.
- The Screw Chiller is designed as soundproof.
Whether it’s long run or short run its natural mechanism does not produce any sound.
The motor of the Screw Chiller also works quietly to prevent sound production.
The motor also prevents the sound of the Compressor to come outside.
- It needs low maintenance as compared to other systems. As it has few spare parts and the parts work for a long time efficiently.
The mechanical system of the Screw Chiller also does not require high-cost maintenance.
However, a regular check-up after intervals is necessary.
- When the high altitude and wider application needs a cooling facility the Screw Chiller will be suitable to consider.
Its mechanism has long pipes that are stretched to a great area of application.
The usage of pipe saves the space for application and it is feasible to connect the entire System.
The long-run compressor is installed that never causes trouble and works without any disturbance.
You don’t need to worry about shifting the Screw Chiller while shifting the whole plant.
It is flexible and customizable to adjust where it works perfectly.
Screw Chiller Shifting
7. What is the Difference Between Screw Chiller and Centrifugal Chiller?
These both are used for providing cooling to industrial applications.
- The component like Screw Compressor, evaporator, thermal expansion valve, and other components are less than Centrifugal.
- The cooling capacity of the compressor is smaller than the centrifugal.
- In the Screw Chiller, it generally ranges lie 30RT-500RT. Its speed is generally low as it is 2950 r / min and the noise value is 75db.
- It has a multi-compressor. If one of the compressors is down and needs maintenance the Screw Chiller keeps working to meet the load of the application.
- The component of the Centrifugal Chiller is the compressor, evaporator, condenser, throttle, suction recovery device, lubrication system, and electronic panel.
- Centrifugal Chiller has more components as compared to Screw Chiller. It has a complex structure and more wearing pants as compared to its alternative.
- The cooling capacity of the Centrifugal Chiller ranges from 150-3000RT.
- One of the downsides of the Centrifugal system is that it has a single compressor.
- So if it goes down and needs maintenance the whole machine needs to stop.
- Its maintenance is also costly. The Centrifugal is higher in speed as compared to the Screw Chiller.
- The speed of centrifugal is 9000 to 4000 r/ min.
The centrifugal Chiller generally produces the sound of 80DB and its noise is higher than Screw Chiller.
8. What is the Working Principle of a Screw Chiller?
The Screw Chiller work in several steps, which include the working of its all components simultaneously.
The state of the Screw Chiller is gas refrigerant after the compressor is compressed it turns into high pressure and high-temperature state.
The compressed gas refrigerant is cooled down and condensed in the condenser under constant pressure.
After the process of Condensation, the gas refrigerant changes into a liquid refrigerant.
Then liquid refrigerant is expanded to the low pressure through an expansion valve. Then it becomes a mixture of gas and liquid.
Then the liquid absorbs the heat under low temperature and pressure. The liquid is to be cooled in an evaporator after the removal of heat.
After cooling, the refrigerant turns into a gas again. The gas state of the refrigerant travels to the compressor and restarts the cycle again.
Screw Chiller Working
9. How to Select Right Screw Chiller for your Application?
- To satisfy the needs of your application there are many sizes, shapes, and capacities of Screw Chiller.
- The detailed statics of the application helps you to choose the right one with well-equipped options.
- One of the main factors that you should consider is the requirements of your application.
- Different features and systems are available in Screw Chiller. The size of the Screw Chiller varies from 10 to 5000 tons.
- It should be selected according to the need of load and the intended cooling capacity required for your plant.
- It is recommended to select Screw Chiller with Screw compressor as it is easy for regulation and it is energy saving.
- The cooling capacity ranges from 100Kw to 860KW. It also depends on your budget.
- The power of the Screw compressor ranges from 38Kw to 178Kw. So you need to select a compressor according to your load.
- The size must be according to the available space. Select the one which has double compressors as it occupies less space.
- Screw Chiller is never affected by external factors and it will help you to run effectively on hotter days and without any interruption.
- You must have clear analyses of the cooling you need and the number of hours the Screw Chiller will operate.
- The pump needs to be replaced gradually and frequently. The pump keeps the flow rate stable even after when the pressure is low.
Also, consider the flow rate of your system. Right flow rate with right temperature increases overall production.
10. How to Size Screw Chiller for your Application?
The size of the Screw Chiller varies. Its size depends on the load of the plant.
Never select the undersize one. The undersize has many problems including unstable temperature and inefficient performance.
Its oversize also makes it inefficient. To select the right size it is better to consult with the experts.
There is E-calculator available on the internet that helps you to size your Screw Chiller. You have to put flow rate, cooling required, and some other data.
However, there are three basic factors to consider before selecting it.
These are the basic factors:
- The flow rate of water
- The water temperature application needs
- The temperature of incoming water.
Do not select the Screw Chiller with a larger size when your application can work on a medium size.
Because the extra-large will be of no use and it will cost more power. So, it might not be cost-efficient.
Before selecting it, clean up space for it. Size the Screw Chiller with maximum Features and options to make it easy and efficient.
The Single compressor is one larger compressor. Dual compressors are two smaller compressors. However, it does not affect the size of the Screw Chiller.
Also, consider the availability of the power supply before selecting it. There is an ideal Screw Chiller that comes with various adjustments and works according to needs.
11. How to Install the Screw Chiller Using Some Tips?
Screw Chiller is very sensitive. It needs to be installed carefully. To avoid any kind of damage, try to move it with a crane.
If the distance is short and within the Installation area, use a fork truck. Foundation is a very important thing for Screw Chiller.
Place an anti-vibration pad between the foundation and Screw Chiller to avoid transmitting vibration and noise.
If you are installing it on the rooftop it is highly recommended to use spring isolators as the sound absorber.
The space for Screw Chiller must be greater than its size. Extra space is needed for air circulating and maintenance.
If Screw Chiller faces directly monsoon rains and the velocity of the monsoon is higher than its fan velocity. It will cause trouble in the process of heat exchanging.
So it is recommended to install it in such a place where does not meet monsoon rains.
The sources of water must be aligned and connected properly. The pipes must be set in a secure place.
A safety valve should also be installed. It keeps the opening pressure below 1.0. Install the manual valve shutoff system in case of maintenance.
All the pipelines from Evaporator should be placed accurately and securely.
The quality standard of water must be good. Install your Screw Chiller in an area that guarantees the quality of water.
As the contaminated water creates algae and other factors which affect its efficiency of working.
12. How to Maintain the Screw Chiller?
The right maintenance increases the life span of your Screw Chiller. However, it comes with spare parts and does not cost expensive maintenance.
It is necessary to check the frequency of vibration of Screw Compressors. The frequent vibration check shows the alignment between the motor and the compressor.
If your Screw Chiller is closed, it is necessary to arrange checkups after every five years.
It has rotors and Screw rotors that need to maintain quarterly to keep its speed high.
Sometimes the contact of Screw rotors with the surface decreases and this results in decreasing efficiency.
The capacity control should be frequently checked for leakages. All seals must be inspected and changed with immediate effect if there are any leakages.
Ensure that the capacity control solenoid valves are fine and operational.
The compressors of the Screw Chiller have bearings. Bearings are the rolling elements. Excessive noise and vibration are produced when the bearings are worn out.
Bearings must be replaced during disassembling of Screw Chiller.
Oil is a very crucial part of it and its life-increasing element for it. The bearings are often worn out because of inefficient lubrication.
The proper grade of oil and at recommended level must be used. Change the first oil after 1 year of Screw Chiller’s operation and then change it after every three years.
The oil filters must be inspected and changed. If a strainer is present on the filter, change it immediately because the strainer resists motors to work fast.
The maintenance of your Screw Chiller must be performed by professionals and experts in the field to avoid any mishandling.
Screw Chiller Maintenance
13. How to Troubleshoot Problems with your Screw Chiller?
Even after the core maintenance and care of the Screw Chiller might get out of order. You need experts to troubleshoot the problems.
Regular Checking Main Connections
If your Screw Chiller shuts down suddenly make sure to check all switches and fuses. Often fuses are blown away and it does not work.
Sometimes the water flow switch disconnects and the water does not pump. Restart the water pump and check the flow again.
Error in Microcomputer
If the microcomputer is not working so check the status of the alarm and inspect the issue. The fault should be set by professionals.
Reliable Source of Water
The total number of gallons of water must be provided to Screw Chiller. Because the insufficient supply of the liquid to the evaporator decreases its efficiency.
If your Screw Chiller does not provide efficient cooling, check the expansion valve, filter, and water pump.
The excess oil makes it deficient. So it is suggested by an expert to keep oil normal and check the oil gauge gradually.
Noise Level Issues
Sometimes the Screw Chiller makes unwanted noise due to the incomplete power supply. The Stable power supply prevents noise production and works at full efficiency.
Resistant in System
The algae-resistant in the Condenser tube decreases the efficiency of the Screw Chiller. It is necessary to check the condenser tube and clean it with cleaning chemicals.
The Screw Chiller also has a motor temperature that’s too high, which may fail the motor coil.
Check the resistance of the motor coil and the Problem will be easily detected and solved.
Screw Chiller Troubleshooting
FAQ of Screw Chiller
- Which Refrigerant is Used in Screw Chiller and What Amount is Used?
Mostly Screw Chiller uses CFC-free gases. These gases work with a higher frequency. The amount of gases depends on the weight of the Screw Chiller and its Size.
The type of refrigerant gas is always labeled on its printed box.
- Which is the Best Heat Fluid for Screw Chiller?
The Screw Chiller works efficiently with a fluid having sterile deionized water or the propylene glycol solution.
- Which Heat fluid Causes Corrosion in Screw Chiller?
Never use antifreeze or inhibitors these are not safe for your Screw Chiller and may cause corrosion.
The manufacturer Of Screw Chiller also suggests Specified fluid for it.
- How to Clean the Condenser of the Screw Chiller?
Shut off the Screw Chiller. Remove the side coverings and disassemble the necessary parts. Take the condenser out clean it with a brush and set it back.
- What is the Amount of Voltage is Needed for Screw Chiller?
The suitable voltage for the Screw Chiller is 480 volts maximum.
- How to Reduce Sound Production of Screw Chiller?
The Screw Chiller comes with sound protection cover or insulation to prevent sound production.
- How Many Gallons Do the Screw Chiller Cool in a Minute?
The cooling capacity of the Screw Chiller depends on the size. Its average cooling capacity starts from 2.4 gallons per minute.
- What is the Noise Value of the Screw Chiller?
The Screw Chiller produces a noise value of 75db.
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