Applicability and comparison of solar-air source heat pump systems between cold and warm regions of plateau by transient simulation and experiment

Solar-air source heat pump (solar-ASHP) system has a potential application in the field of hot water and space heating in residential buildings. Such system features the complementary advantages to solve the discontinuous operation of the single solar system and the frosting issue of the single ASHP system. This paper built the solar-ASHP systems in Kunming and Shangri-La, and tested the system performance under different weather conditions in these two regions of plateau. Meanwhile, the transient heat balance models of the system were established under the sunlight time and non-sunlight time and were verified by the experimental results. Moreover, the verified model was applied to reveal the energy balance performance between the energy supply and building heat demand. The law of the system performance affected by the ambient temperature, effective heat collecting area, and cumulative heating capacity of collector was explored by the validated model. The results indicate that when the ambient temperature decreases by 1 degrees C during non-sunlight time, the energy efficiency ratio decreases by about 0.07. A square meter decline in the effective heat collecting area pushes an increase in the heating capacity of 5.75 MJ. Meanwhile, the cumulative heating capacity of collector increases by 5 MJ, and the ASHP energy consumption decreases by 0.54 kWh. The dynamic changes of the ambient temperature and instantaneous solar radiation are the main reasons of the heat balance errors. Therefore, both the developed system and model are feasible and reliable in different climate regions.

Automated summary

The study investigated the performance of a solar-air source heat pump system in plateau regions and established a heat balance model to explore the factors influencing system performance such as ambient temperature, heat collecting area, and collector heating capacity. The results showed that a decrease in ambient temperature during non-sunlight time led to a reduction in energy efficiency ratio, while a decrease in effective heat collecting area increased heating capacity.