Calculation and analysis of primary energy utilization rate of heat pumps

 The power generation link is considered as a coal-fired power plant, and the primary energy thermal efficiency and exergy efficiency are calculated and analysed for the air-source heat pump hot water heating system. The results show that the primary energy thermal efficiency is greater than 100% when the COP of the heat pump unit is 3 and 4, however, the primary energy exergy efficiency of the heat pump unit and heat pump system is much lower than 100%. The primary energy exergy efficiency of the heat pump heating system indicates the degree of utilization of the primary energy exergy value in heat pump heating systems, which can be called the primary energy utilization rate of the heat pump heating system. Although the COP and the primary energy thermal efficiency of the heat pump unit can not directly reflect the utilization degree of primary energy exergy value, they are all in direct proportion to the exergy efficiency of the primary energy of the heat pump heating system, so they can also be used to compare and evaluate the energy efficiency of the heat pump heating system. Reducing the output water temperature of the heat pump unit can increase the COP, thus improving the exergy efficiency of heat pump heating systems, achieving the same heating goal and reducing the consumption of primary energy.