The cooling effect produced is quantified as tons of refrigeration.
1 ton of refrigeration = 3024 kCal/hr heat rejected.
The refrigeration TR is assessed as
The theoretical Coefficient of Performance (Carnot), COPCarnont - a standard measure of refrigeration efficiency of an ideal refrigeration system- depends on two key system temperatures, namely, evaporator temperature Te and condenser temperature Tc with COP being given as:
This expression also indicates that higher COPCarnot is achieved with higher evaporator temperature and lower condenser temperature.
But COPCarnot is only a ratio of temperatures, and hence does not take into account the type of compressor. Hence the COP normally used in the industry is given by
Payback of energy saving options
Experiences from the past have shown that upgrading the HVAC can reduce energy costs considerably. The following table gives some examples for the payback of such investments.
| Options | Extimated Payback Period |
|---|---|
| Effective use of Ice stem in dairy industry | 6 months |
| Heat recovery from refrigeration compressor discharge by installing a de-superheater | 1 year |
| Installation of VFD for chilled water pump | 1 year |
| Replace reciprocating refrigeration compressors with centrifugal/screw compressors | 2 year |
| Replace ofwindow type A/C with split type A/C | 3 years |
| Use of air-curtains to reduce cooling load | 6 months |
| Segregation and isolation of area that does not require cooling | 6 months |
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