Performance of a transcritical CO2 heat pump for the food processing industries

New Zealand food processing industries have a simultaneous need for refrigeration below 10 degrees C and heating of water to greater than 80 degrees C. A prototype transcritical CO2 heat pump was constructed for this purpose and its performance was measured across a range of operating conditions. The combined heating and cooling coefficient of performance (COP) of the prototype was about 5 when producing hot water at 90 degrees C and refrigeration at less than 0 degrees C. This performance was consistent with previous theoretical predictions, and could be further improved if a higher efficiency compressor was used and the heat exchanger sizes were optimised. The market potential for the technology is good because it is well matched to the requirements of many food processing industries and the energy efficiency is high compared with traditional heating and cooling systems.