大型过量供给光伏-热泵系统在冬季工况下带机械泵的性能分析

Abstract The direct-expansion supply method is typically limited to small-scale photovoltaic-thermal systems due to evaporator superheat and refrigerant maldistribution. In this study, a novel, large-scale, overfeed photovoltaic-thermal heat pump integrated with a mechanical pump was proposed, developed, and applied. The system comprised a four-compressor parallel rack and a photovoltaic–thermal array with 84 modules. The study comparatively analysed the operating characteristics and heating performance of the proposed under typical winter conditions. The results demonstrated that the system operated stably under diverse conditions, with discharge temperatures below 110 °C and suction superheat variation within 0–3.3 K. On a sunny day (ambient temperature, 1.1 °C), the coefficient of performance averaged 2.91 while heating water from 12.4 °C to 72.2 °C. Even under snowy conditions (−9.3 °C), the system heated water from 12.9 °C to 60.0 °C. The overall performance of the water heating process over 18 winter days was evaluated, yielding an average coefficient of performance of 2.440 for target temperatures above 70 °C water and 2.552 at 60 °C. In addition, a novel indicator for evaluating the thermoelectric performance of the Photovoltaic-thermal heat pump was introduced. The indicator value for producing 60 °C water remained positive on 75 % of the tested days, indicating the potential for power self-sufficiency. These findings provide valuable insights for the development and application of large-scale photovoltaic-thermal heat pump systems and highlight their promise for future sustainable heating solutions.