A chiller is a machine that produces chilled water for air conditioning. There are two main types based on refrigeration cycle: vapor compression and absorption. There are also two types based on condensation process: air-cooled and water-cooled. The key components of a chiller system include the chiller (with evaporator and condenser cylinders), compressors, pumps, cooling towers, and load terminals. The chiller circulates chilled water to air handlers to transfer heat from the air to the water, which then returns to the evaporator to transfer heat to refrigerant before being compressed and releasing heat in the condenser. Performance is measured in tons of refrigeration, kW/ton efficiency rating, COP, and

2. CONTENTS CHILLER BASICS WORKING PRINCIPLE OF CHILLER
• REFRIGERATION CYCLE
• CHILLER COMPONENTS
• COMPONENTS FUNCTIONS & COMPARISON
• LOAD TERMINAL CONTROL OPTIONS
• CHILLER SYSTEM CONFIGURATION
• TECHNICAL TERMINOLOGY
• CHILLLER PERFORMANCE MEASUREMENT

3. CHILLER BASICS What is a Chiller?
The refrigeration machine that produces chilled water is referred
to as a “Chiller”. A chiller is a water-cooled air conditioning
system that cools inside air, creating a more comfortable and
productive environment.
Basically, there are two types of chillers based upon the
refrigeration cycle:
1. Vapor Compression Chiller
2. Absorption Refrigeration Chiller
Based upon the condensation process of working fluid , there are
two types of chiller:
1. Air-Cooled Chiller

4. Chiller is the producers of chilled water in this
system.
The chiller has two main cylinders:-
ones the evaporator the chilled or cold water
produced, and other cylinder is the condenser
collected of heat of building and sent to the
cooling towers.

5. CHILLED WATER SYTEM COMPONENETS
1. Chiller (Evaporator)
2. Compressors
3. Chilled Water Pumps
4. ACC in Air Cooled Chiller
5. Cooling Tower in Water-cooled Chiller
6. Condensate water pumps in water-cooled chiller
7. Load Terminals (chilled water cooling coils)
8. Chilled and condenser-water distribution systems include piping, expansion valve,
control valve, check valves, strainers etc.

7. WORKING OF CHILLER SYSTEM
1-Chillers circulate chilled water to air-handlers(AHU’s) in order to transfer
heat from air to water.
2-This water then returns to the evaporator side of the chiller where the
heat is passed from the water to a liquid (LP) refrigerant .
3-The refrigerant leaves the evaporator as a cold vapor (LP) and enters the
compressor where it is compressed into a hot vapor (HP).
4-Upon leaving the compressor, the vapor enters the condenser side of the
chiller where heat is transferred from the refrigerant to the air/water side
of the condenser where it is circulated to an ACC/open cooling tower for
the final removal of heat from the refrigerant as a liquid (HP).

11. WORKING OF CHILLER SYSTEM

12. EVAPORATOR

13. EXPANSION VALVE

14. Water cycle in the evaporator
Evaporator

15. Water cycle in the condenser
condenser

18. Air cooled chiller

22. 1.Tons of refrigeration (TR):
One ton of refrigeration is the amount of cooling obtained by one ton of ice
melting in one day i.e. kcal/h or thermal kW.
2. Net Refrigerating Capacity:
A quantity defined as the mass flow rate of the evaporator water multiplied by
the difference in enthalpy of water entering and leaving the cooler, expressed in
kcal/h, tons of Refrigeration.
3. kW/ton rating:
Commonly referred to as efficiency, but actually power input to compressor
motor divided by tons of cooling produced, or kilowatts per ton (kW/ton). Lower
kW/ton indicates higher efficiency.
TERMINOLOGY

23. 4.Coefficient of Performance (COP):
Chiller efficiency measured in cooling output (kcal/hr) divided by electric power input.
5. Energy Efficiency Ratio (EER):
Performance of smaller chillers and rooftop units is frequently measured in EER rather
than kW/ton. EER is calculated by dividing a chiller's cooling capacity (in kcal/h) by its
power input (in watts) at full-load conditions. The higher the EER, the more efficient the
unit.
TERMINOLOGY

25. ● The refrigeration TR is assessed as
TR = Q x Cp x (Ti – To) / 3024
Where Q is mass flow rate of coolant in kg/hr
Cp is coolant specific heat in kCal /kg deg C
Ti is inlet, temperature of coolant to evaporator (chiller) in °C
To is outlet temperature of coolant from evaporator (chiller) in °C.
The above TR is also called as chiller tonnage.
● The specific power consumption kW/TR is a useful indicator of the performance of
refrigeration system. By measuring refrigeration duty performed in TR and the kilowatt
inputs, kW/TR is used as a reference energy performance indicator.
PERFORMANCE ASSESSMENT OF CHILLER SYSTEM

26. ● In a centralized chilled water system, apart from the
compressor unit, power is also consumed by the chilled
water (secondary) coolant pump as well condenser water
(for heat rejection to cooling tower) pump and cooling
tower fan in the cooling tower.
Effectively, the overall energy consumption would be
towards:
– Compressor kW
– Chilled water pump kW
– Condenser water pump kW
– Cooling tower fan kW, for induced / forced draft towers

27. Chiller cooling capacity

32. For a 350 kW chiller with a 7 °C rise in chilled water
temperature and a 4.5 °C drop in cooling tower’s
condensing water, calculate the volume flow rates of
chilled and condensing water.