Theoretical analysis of energy-saving performance and economics of CO2 and NH3 heat pumps with simultaneous cooling and heating applications in food processing

• CO2 and NH3 heat pumps for combined cooling and heating applications are proposed.
• The performances of the proposed heat pumps are analyzed and simulated.
• Energy-saving performance and economics of the heat pumps are analyzed.

Food processing has significant simultaneous requirements of cooling, warm water and hot water. In order to reduce energy consumption and greenhouse gases emission, one type of NH3 heat pump and two types of transcritical CO2 heat pumps are proposed. These natural refrigerant heat pumps can supply not only cooling, but also warm water and hot water simultaneously. The characteristics and performance of the heat pumps are analyzed and simulated. Annual primary energy saving and annual operation cost saving are predicted for California, Wisconsin, New York, and Florida. Research results show that the maximum possible value of annual primary energy-saving rates using the CO2 heat pumps ranges from 56% to 65%, and using the NH3 heat pump is approximately 44%; the maximum possible value of annual operation cost saving rates using the CO2 heat pumps ranges from 50% to 66%, and using the NH3 heat pump is from 20% to 47%.