Evaporation temperature prediction of a direct-expansion solar-assisted heat pump

Abstract

As known, evaporation temperature is critical for the thermal performance of a direct-expansion solar-assisted heat pump (DX-SAHP), which is subjected to environmental parameters. It is significant to explore the effect of environmental parameters on evaporation temperature and system performance for the optimal design of DX-SAHP systems. An experimental study on the affecting factors of evaporation temperature in DX-SAHP is firstly implemented, and an evaporation temperature prediction model is constructed by multiple linear regression method and validated, which uses solar radiation, ambient temperature and wind speed as independent variables. Based on this, the effect of environmental parameters on evaporation temperature is compared and analyzed. Results show that evaporation temperature is most affected by solar radiation, followed by ambient temperature and wind speed. The weights of solar radiation, ambient temperature and wind speed are 47.6 %, 43.1 % and 9.3 %, respectively. Furthermore, evaporation temperature will have a 1.80, 0.58 and 0.94 °C increase for a 100 W·m−2 increase in solar radiation, a 1 °C increase in ambient temperature and a 1 m·s−1 increase in wind speed, respectively. The prediction model obtains satisfactory accuracy under different conditions and would be helpful for optimal design and thermal performance improvement of DX-SAHP systems.