Chiller
A chiller is a refrigeration system that removes heat from a liquid (typically water or a water-glycol mixture) and circulates it through a heat exchanger to cool industrial machinery, HVAC systems, or process equipment. Unlike cooling towers (which reject heat to the atmosphere), chillers use a refrigeration cycle to provide precise temperature control.
Types of Chillers
1. Based on Condenser Cooling Method
| Type | How It Works | Pros | Cons | Applications |
| Air-Cooled Chiller | Uses fans to reject heat to ambient air. | ✔ No cooling water needed ✔ Lower maintenance | ✖ Less efficient in high temps ✖ Louder | Small/medium buildings, rooftop units |
| Water-Cooled Chiller | Uses cooling tower water to remove heat. | ✔ Higher efficiency ✔ Quieter operation | ✖ Requires cooling tower & pumps ✖ More maintenance | Large commercial/industrial systems |
Based on Refrigeration Cycle
| Type | Mechanism | Efficiency | Best For |
| Vapor Compression Chiller | Uses compressor, condenser, expansion valve, evaporator. | High | Most common (HVAC, industrial) |
| Vapor Absorption Chiller | Uses heat (steam/waste heat) instead of a compressor. | Lower, but energy-saving | Waste heat recovery, solar cooling |
3. Based on Compressor Type
- Scroll Chiller – Reliable, medium capacity (HVAC).
- Screw Chiller – High efficiency, large capacity (industrial).
- Centrifugal Chiller – Very large capacity (hospitals, data centers).
- Reciprocating Chiller – Older tech, declining use.
Working Principle (Vapor Compression Cycle)
- Evaporator – Chilled water absorbs heat, cooling the process.
- Compressor – Refrigerant gas is compressed, raising its temperature.
- Condenser – Heat is rejected (to air or water).
- Expansion Valve – Refrigerant pressure drops, cooling it before re-entering the evaporator.
Key Components
- Compressor – Increases refrigerant pressure.
- Condenser – Releases heat to air/water.
- Evaporator – Absorbs heat from process water.
- Expansion Valve – Regulates refrigerant flow.
- Control Panel – Manages temperature & efficiency.
Applications
✔ HVAC Systems – Office buildings, malls, hospitals.
✔ Industrial Processes – Plastic moulding, laser cooling, food processing.
✔ Data Centres – Prevents server overheating.
✔ Medical & Labs – MRI machines, precision cooling.