The basic principle of compressor-based cooling systems:

Extracting heat away from the area you want to cool, by manipulating the pressure of the working refrigerant (air, water, synthetic refrigerants, etc.) through a cycle of compression and expansion.

 

Simpler: by investing electricity cooling is produced by using an external heat source (external air, ground water, cooling tower, etc.)

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To operate the cooling cycle, a refrigerant is used that can be evaporated at the temperature required for cooling and (at a higher pressure) condensed at ambient temperature (or at a temperature of the available source, it can be ground water for liquid-cooled chillers). The refrigerant evaporates at the appropriate temperature (correspondingly low pressure) and thus has a cooling effect. The evaporated refrigerant is continuously removed by the compressor and compressed to a pressure that can be condensed (liquefied) at a certain temperature using the natural heat-absorbing media available in the environment (water or air). The liquid high-pressure refrigerant is able to cool again after depressurization (expansion valve).

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EER (COP)

The cooling efficiency of refrigeration equipment is expressed in EER (Energy Efficiency Ratio). It is often used in the same way as the COP (Coefficient Of Performance) indicator, the point for us is that if cooling is the goal, we count on cooling efficiency, either called EER or COP. (basic difference as definition: COP: heating efficiency, EER: cooling efficiency)

 

EER = cooling thermal power / electrical power consumption (which is the sum of the power of the compressor, fans and other equipment) - unit: kW/kW

 

EER values are given at full load under predetermined measurement conditions (usually 35 ° C for cooling). Typical value of EER for older refrigerators: 2.3 ÷ 2.9; for newer refrigerators: 2.7 ÷ 4.1.

Note: Catalogues may give a much higher value than this, they are usually not real.

Note: The EER may be given in Btuh/W, in which case the EER can easily be greater than 10, dived by about 3.4 to give the W/W.