A novel dynamic operation method for solar assisted air source heat pump systems: Optimization control and performance analysis

The solar collector is a key component of solar assisted air source heat pump (SAASHP) systems that absorbs solar energy and converts it into heat, significantly affecting the system performance. The traditional control method (TCM) for solar collector in SAASHP systems utilizes several key parameters: the upper and lower limit temperature differences, and the flow rate of pump. However, these parameters were set to constant values and cannot be adjusted for varying solar irradiance, resulting in poor system performance. To solve the above problem, this study proposed a novel dynamic operation method (DOM) for SAASHP systems, and investigated its performance and feasibility using a university dormitory hot water supply as an example. TRNSYS was used to simulate the SAASHP system and the accuracy of the model was verified by field test. The results showed that the DOM dynamically adapted control parameters according to the solar irradiance, thus significantly enhancing the solar energy utilization. For the DOM, the thermal efficiency of solar collector was 34.2 % and the system coefficient of performance was 4.58, which improved by 11.8 % (6.5 %) and 8.3 % (3.4 %), respectively, compared to the pre-optimization (post-optimization) TCM. In addition, the DOM exhibited excellent performance in different climate zones of China.