The performance experiment of an air-source heat pump with multi-stage waste heat recovery

Abstract

To improve the efficiency of the air-source heat pump system and improve the stability of operation, the experimental prototype of an air source heat pump system with multi-stage waste heat recovery is independently designed and processed, and the performance of the heat pump system is studied in Xi'an area as an example. The heat pump outlet's heat air temperature is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{40^{\circ}C, 45^{\circ}C}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{50^{\mathrm{o}}C}$</tex> respectively. Combined with the operation modes of 5 heat pump systems, the performance test of 15 sets of heat pump system experimental prototypes is tested. The experimental results show that the multi-stage waste heat recovery subsystem can effectively improve the COP of the air source heat pump experimental prototype. When the set temperature of the air outlet is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{50^{\mathrm{o}}C}$</tex> , the energy efficiency of the multi-stage air source heat pump system for waste heat recovery can be increased by 22.2% compared with the COP air source heat pump, and the heat recovery rate of the waste heat recovery system can be up to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{88\%\sim 94\%}$</tex> . With the increase in ambient temperature, the COP of the heat pump system increases significantly under each working condition. The indoor control mode under different outdoor temperatures also restricts the unit's performance. The overall performance of the heat pump experimental prototype is relatively best when the two-stage and three-stage heat recovery are connected in series with the first-stage heat recovery working mode. From the perspective of stable operation and maintenance of the air source heat pump system, the first-stage heat recovery and the working mode of three-stage heat recovery in series is more suitable, and the indoor heating effect of the heat pump experimental prototype is relatively stable.