Calculate chiller efficiency (COP), cooling, or power consumed by entering any 2 values and choosing units in BTU/hr, kW, hp, or W.
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Chiller Efficiency Formula
Chiller efficiency is commonly expressed as coefficient of performance, or COP. COP compares useful cooling output to electrical power input after both are expressed in compatible energy-rate units.
- COP = chiller coefficient of performance
- Q = cooling capacity in BTU/hr
- P = power consumed in watts
- 3.412141633 = BTU/hr produced by 1 watt of power
The calculator uses these formulas in three ways:
- Find COP: enter cooling and power. The calculator converts cooling to BTU/hr, converts power to watts, then divides cooling output by power input.
- Find cooling: enter power and COP. The calculator multiplies power by 3.412141633 and then by COP to estimate cooling output.
- Find power consumed: enter cooling and COP. The calculator divides cooling by COP and by 3.412141633 to estimate electrical power input.
Chiller Unit Conversions and COP Reference
These are the unit conversions used for cooling and power inputs.
| Quantity | Unit | Base-unit conversion |
|---|---|---|
| Cooling | BTU/hr | 1 BTU/hr |
| Cooling | kW | 1 kW cooling = 3412.14 BTU/hr |
| Cooling | hp | 1 hp cooling = 2544.43 BTU/hr |
| Power | W | 1 W |
| Power | kW | 1 kW = 1000 W |
| Power | hp | 1 hp = 745.7 W |
A higher COP means the chiller produces more cooling for each unit of electrical input.
| COP range | Approximate kW/ton | General interpretation |
|---|---|---|
| 2.5 to 3.5 | 1.41 to 1.00 | Lower efficiency, often seen in older or less favorable operating conditions |
| 3.5 to 5.0 | 1.00 to 0.70 | Common operating range for many chillers |
| 5.0 to 7.0 | 0.70 to 0.50 | Efficient operation, often associated with favorable temperatures and well-maintained equipment |
| Above 7.0 | Below 0.50 | Very high efficiency, usually dependent on chiller type and operating conditions |
Examples
Example 1: Calculate COP
You have a chiller producing 500,000 BTU/hr of cooling while consuming 40 kW of power.
- Cooling: 500,000 BTU/hr
- Power: 40 kW = 40,000 W
The chiller efficiency is about 3.66 COP.
Example 2: Calculate Power Consumed
You have 1,000 kW of cooling and a COP of 5.2. Find the power consumed in kW.
- Cooling: 1,000 kW = 3,412,140 BTU/hr
- COP: 5.2
The estimated power consumed is about 192.3 kW.
FAQ
What is a good COP for a chiller?
A good COP depends on the chiller type, load, condenser water temperature, evaporator temperature, and maintenance condition. Many chillers operate somewhere around 3.5 to 6.0 COP, while efficient systems under favorable conditions can be higher. Compare COP values only when the operating conditions are similar.
Is a higher COP always better?
Yes, for the same cooling job, a higher COP means less electrical power is needed. For example, a COP of 5 means the chiller provides 5 units of cooling for every 1 unit of electrical input. However, COP changes with load and temperature, so one reading does not describe performance under all conditions.
What is the difference between COP and kW per ton?
COP increases as efficiency improves. kW per ton decreases as efficiency improves. They describe the same idea from opposite directions. The common conversion is:
