Category: Compressors used in Chillers

The use of reciprocating chillers is less common in high-efficiency systems. However, these compressors can still be found in new chillers, primarily designed for low thermal loads.

The operation of a piston compressor chiller is as follows:

• The refrigerant, in its vapor state, is compressed by a piston inside a cylinder.
• A thin layer of oil prevents the refrigerant vapor from escaping the compression chamber and serves to lubricate the system and reduce friction.
• The piston is connected to the crankshaft via the piston rod.
• As the crankshaft rotates, it causes the piston to move back and forth within the cylinder.
• This reciprocating movement draws the refrigerant into the cylinder and compresses it.
• The compressed refrigerant is then discharged to the chiller condenser.
• The piston compressor is equipped with intake and discharge valves, which trap the refrigerant vapor inside the cylinder.
• During the intake stroke, the intake valve is open, while during the compression stroke, both valves are closed.
• As the pressure increases, the exhaust valve opens, allowing the refrigerant to escape.
• For applications requiring less cooling, the chiller with a piston compressor can regulate its capacity.
• This is achieved using a hot gas bypass valve located in the compressor discharge zone.
• The hot gas is directed to the suction or inlet of the evaporator to simulate heat. However, the hot gas method does not offer energy efficiency advantages and can maintain acceptable refrigerant speed for oil return.
• Most reciprocating compressors above 10 tons of refrigeration or 35 kW are equipped with cylinder unloaders to regulate their capacity.
• Unloaders work by deactivating and activating the passage of refrigerant to the piston compressor’s compression chamber.
• A solenoid valve controls the refrigerant flow, directing the pressurized compressor discharge refrigerant to the top to shut off and interrupt the refrigerant vapor flow to the cylinder suction.
• Although the piston continues to move back and forth inside the cylinder, it no longer performs compression as it cannot absorb refrigerant vapor.

For comprehensive learning about chillers, we have prepared a complete training program on chilled water installations with chillers.

Chiller Training Courses

If you need a reliable and high-performance machine for cooling water flows, the rotary screw compressor chiller might be just what you’re looking for.

These machines are designed to operate using a compression refrigeration cycle, making them ideal for medium to high refrigeration power ranges. With cooling capacities ranging from 20 tons to 1,000 tons of refrigeration, there is a chiller available to suit your needs.

How do screw compressors work?

• A screw compressor is a machine that increases the pressure of refrigerant gas that has been evaporated in the chiller. This high-pressure refrigerant is then sent to the condenser, where it is turned back into a liquid.
• The screw compressor works by reducing its volume through the rotation of slotted helical screws within a tight tolerance housing.
• The double rotor screw compressor is the most commonly used compressor in larger refrigeration installations, where the rotors rotate in opposite directions to draw gas into the rotors through an inlet port.
• As the screws continue to turn, gas is trapped between the compressor housings and the rotors, and is released through an outlet port at a determined discharge pressure value.

What is the most common refrigerant used in screw chillers?

• The most commonly used refrigerant in screw chillers is R-134A. However, due to environmental restrictions, newer refrigerants such as R513A have also been introduced.
• Some screw chillers also use R410A, although this refrigerant has been replaced by more environmentally friendly options due to its high GWP value.

Which screw chiller is the best seller?

The best-selling chiller is the screw compressor with a water chiller in the range of 100 to 300 KW.

Popular Models of Screw Chillers:

Check out our table of the most commonly used models of screw chillers.

In this table, we have models of Screw Chillers and their main characteristics:

Chiller Model	Chiller Gas	Cooling Capacity	Cooling of Condenser
AquaForce 30XA	Carrier R134a	80 – 500 TR	Air-Cooled
AquaForce 30XV	Carrier R-134a	490 – 1755 TR	Air-Cooled
AquaForce 30HX	Carrier R-134a	75 – 265 TR	Water-Cooled
AquaEdge 23XRV	Carrier R-134a	175 – 550 TR	Water-Cooled
AquaForce 30XW	Carrier R-134a	150 – 400 TR	Water-Cooled
York YVAA	R-410A	150 – 575 TR	Air-Cooled
York YVFA	R-410A	150 – 500 TR	Air-Cooled
York YCIV	R-410A	150 – 400 TR	Air-Cooled
Trane RTAE	R134a	150 – 300 TR	Air-Cooled
Trane RTAC	R-134a	140 – 500 TR	Air-Cooled
Daikin Pathfinder	R-134a	100 – 565 TR	Air-Cooled
Daikin Navigator	R-134a	120 – 300 TR	Air-Cooled

Where to learn all about chillers?

We have prepared a complete training in chilled water installations with chillers.

Chiller Training Courses

The scroll compressor chiller is a widely used cooling system in low-capacity applications.

• This chiller operates on a compression refrigeration circuit and is suitable for low to medium thermal loads. It can be equipped with either an air-cooled or water-cooled condenser.
• Each individual scroll compressor typically handles refrigeration capacities of less than 25 tons. To achieve higher cooling power, multiple scroll compressors can be used in parallel.
• Scroll compressors boast high efficiency, and when combined with inverter technology, they can further optimize the efficiency of the chilled water plant.
• The design of parallel scroll compressors requires meticulous lubrication control, which is ideally automated for ease of operation.
• Characteristics of scroll chillers include a hermetic squirrel cage induction motor, cooled by suction gas, contributing to its longevity and stability. The elimination of suction valves in scroll compressors reduces valve losses and enhances efficiency.
• By utilizing multiple scroll compressors, the chiller’s capacity can be adjusted according to the plant’s demand, offering a degree of redundancy in case of compressor failure.
• However, the presence of more compressors may slightly increase the probability of failures, but the overall reliability of scroll compressors due to their few moving parts mitigates this concern.
• Inverter-type scroll compressor chillers enable adaptability to varying cold needs within the plant, improving overall efficiency.
• To maximize the chiller’s performance, an oil equalization system must be implemented to ensure consistent and reliable operation.
• Chillers with scroll compressors are available in various refrigerants, including R22, R407C, R134a, R404A, and R410A.

For comprehensive learning on chilled water installations and chillers, we offer a complete training program.

Chiller Training Courses

The Water Cooled Centrifugal Chiller is a fantastic machine that uses a compression refrigeration cycle to generate massive amounts of ice water for applications with high thermal loads.

The best part? It’s surprisingly simple to understand!

• This chiller uses a centrifugal compressor with an impeller wheel that spins at a high speed.
• As the coolant enters, it acquires the speed of the impellers and moves radially under the effect of centrifugal force.
• The refrigerant then leaves the impeller and enters the compressor volute, which is a curved funnel that increases in area as it approaches the discharge port. By doing this, it increases its cross-sectional area to convert the speed of the refrigerant into pressure. This results in coolant that has high pressure and is ready for use!
• Centrifugal chillers are perfect for handling large amounts of thermal load and typically have a water-cooled condenser.
• They also have few friction parts, which means they’re very efficient and easy to maintain. Plus, the frictionless operation means that the vibration of the chiller is close to zero.
• To control the capacity of the compressor, vanes at the inlet of the centrifugal compressor are used. As the blades close, the flow of refrigerant entering the compressor reduces, and the compressor revolutions are reduced to generate the required pressure.
• Magnetic bearings improve the efficiency and increase the life of the machine, and some centrifugal chillers do not require oil.
• Not using oil increases the efficiency of the chiller heat exchangers. The partial load efficiency indicator “IPLV” can reach 13, and the chiller can consume 30 to 50% less energy. Centrifugal chillers can have a useful life of up to 30 years.
• In summary, the Water Cooled Centrifugal Chiller is a reliable and efficient machine that can handle large amounts of thermal load. Its simple operation, low maintenance, and energy efficiency make it an excellent option for any application with high thermal loads.