Warm return water enters the chiller evaporator. The refrigerant absorbs heat from the water and changes from a low-pressure liquid into vapour.

The refrigerant vapour enters the chiller screw compressor. Rotating screw rotors reduce the available space inside the compressor, increasing refrigerant pressure and temperature.

The high-pressure refrigerant then enters the water-cooled condenser. Condenser water removes heat from the refrigerant, causing it to return to a liquid state.

The refrigerant passes through an electronic expansion valve, where its pressure and temperature are reduced. The low-pressure refrigerant returns to the evaporator and begins the cooling cycle again.

This continuous process produces chilled water for commercial comfort cooling or industrial process cooling.

The rotary screw compressor is the main component of a water screw chiller. It generally uses one or two rotating screw-shaped rotors to compress refrigerant.

A rotary screw chiller provides continuous refrigerant compression with relatively low vibration. Capacity can be controlled using slide valves, compressor staging or variable-speed operation.

A twin-screw compressor chiller uses two intermeshing rotors. One rotor drives the compression process while the other follows the rotor profile.

A twin-screw compressor chiller system is suitable for commercial and industrial installations requiring stable cooling output and efficient capacity control.

Twin-screw systems can be configured with:

A single-screw chiller uses a main screw rotor and matching gate rotors to compress refrigerant.

This configuration can provide balanced compression forces and smooth operation. Its suitability depends on the required capacity, equipment availability and project specifications.

The evaporator removes heat from the chilled-water circuit. Water-cooled screw chillers commonly use a shell-and-tube evaporator, flooded evaporator or falling-film evaporator.

#### H3: Flooded Evaporator

In a flooded screw chiller, liquid refrigerant surrounds the evaporator tubes. Chilled water flows through the tubes while the refrigerant absorbs heat and evaporates.

A flooded evaporator provides effective heat transfer and is commonly used in medium- and high-capacity chiller systems.

#### H3: Falling-Film Evaporator

A falling-film evaporator distributes refrigerant across the outer surface of the evaporator tubes. The refrigerant forms a thin film while absorbing heat from the water inside the tubes.

A falling-film evaporator chiller can reduce refrigerant charge and support efficient heat transfer when correctly designed and controlled.

The water-cooled condenser transfers heat from the refrigerant to the condenser-water circuit.

A shell-and-tube condenser commonly consists of condenser water flowing through tubes while the refrigerant condenses around them. The heated condenser water then travels to the cooling tower.

Proper condenser-water flow and clean heat-transfer surfaces are essential for efficient operation.

The electronic expansion valve controls refrigerant flow into the evaporator.

It adjusts according to operating conditions, helping maintain correct refrigerant feeding, evaporator performance and compressor protection.

The chilled-water pump circulates cooled water between the chiller and the building or industrial process.

Depending on the system design, the chilled-water circuit may include:

The condenser-water pump circulates water between the chiller condenser and the cooling tower.

The pump must provide the required water flow while overcoming pressure losses through the condenser, piping, valves and cooling tower.

The cooling tower system rejects heat absorbed by the condenser water.

A complete cooling tower and screw chiller installation may include:

A buffer tank increases the water volume in the chilled-water circuit. It helps stabilise water temperature and reduces excessive compressor cycling during low-load operation.

Buffer tanks are particularly useful where process loads change rapidly or the chilled-water system has limited water volume.

An expansion tank accommodates changes in water volume caused by temperature variation.

Correct sizing and placement help maintain stable system pressure and protect chilled-water components.

The water-treatment system helps protect condenser tubes, cooling towers and piping against scale, corrosion and biological growth.

Water treatment may include:

The chiller control panel manages compressor operation, refrigerant control, water-flow safety and system alarms.

A modern PLC-controlled chiller can monitor:

A BMS-integrated chiller can communicate with the building management system for central monitoring, operating schedules, alarm reporting and performance analysis.

Screw chillers are suitable for cooling capacities that exceed many scroll chiller applications while remaining practical for facilities where centrifugal technology may not be required.

They can serve individual buildings, industrial processes or complete chilled-water plants.

The continuous rotary compression process supports stable chilled-water production under changing operating conditions.

This makes screw chillers suitable for facilities requiring dependable comfort cooling or precise process temperatures.

Cooling demand often changes throughout the day. A variable-speed screw chiller or multi-compressor system can reduce output during lower demand.

Efficient part-load operation helps reduce energy consumption and unnecessary compressor cycling.

Chiller COP measures the relationship between cooling output and electrical power consumption.

A higher chiller COP indicates more efficient operation under the measured conditions.

Actual COP depends on:

Chiller IPLV represents performance at several part-load conditions.

It is an important consideration because most commercial and industrial chillers do not continuously operate at full capacity.

Rotary screw compressors provide continuous compression with fewer pressure pulses than reciprocating compressors.

This supports smooth operation and relatively low vibration.

Screw chillers can use:

These options allow the system to match cooling output with changing demand.

A water-cooled screw chiller can serve multiple air handling units, process machines or building zones from a central plant.

Centralised systems provide:

Chiller sequencing determines which chillers and pumps should operate at each cooling-load condition.

Correct sequencing can:

Chiller plant automation coordinates chillers, chilled-water pumps, condenser-water pumps and cooling towers.

Automation can include:

A water-cooled screw chiller for commercial buildings can supply chilled water to air handling units and fan coil units throughout the property.

Applications include:

A water-cooled chiller for hotels and hospitals must provide stable cooling under changing occupancy and operational requirements.

Multi-compressor and variable-speed configurations can support efficient operation during both peak and reduced loads.

A screw chiller for malls and office buildings provides centralised comfort cooling with flexible capacity control.

BMS integration allows facility teams to supervise temperatures, alarms and operating schedules from a central system.

A water-cooled screw chiller for data centres can support precision air-conditioning units, air handling systems and high-density technology environments.

Data centre installations may require:

A screw chiller for factories and manufacturing plants can provide chilled water for machinery, production lines, hydraulic systems, process heat exchangers and environmental cooling.

An industrial process cooling screw chiller is suitable for applications requiring stable fluid temperature during manufacturing.

Applications can include:

A glycol screw chiller for industrial applications can provide low-temperature cooling and freezing protection.

The correct glycol percentage, evaporator design, pump selection and control settings must be determined during system design.

A low-temperature process cooling chiller is selected for industrial applications that require fluid temperatures below standard comfort-cooling conditions.

The design must consider: