Study on the Energy Efficiency Improvement and Operation Optimization of a Solar Water Heating System

The solar-assisted electric boiler water heating systems adopted in student apartments at universities have some shortcomings, such as unsuitable system designs, unstable water supply temperature, and excessive power consumption. As discussed in this paper, the hot water supply system was reformed, and two apartments with the same building area, same solar collector area, and similar water consumption were selected to be used in comparative experiments. The auxiliary heat source for one of the apartments was changed from an electric boiler to three air source heat pumps, and a constant temperature water tank was added to form a double-tank water supply system. In addition, the operation strategy was adjusted. The other apartment was not modified. The energy consumption, solar fraction, water supply quality and economy of the two systems were analyzed and compared. The results showed that the transformation plan is reasonable and feasible. The solar fraction of the reformed system was significantly improved. The water supply temperature of the original system ranged from 35 °C to 60 °C, but it was shown to stabilize between 40 °C and 50 °C after the transformation. The average power saving rate of the reformed system reached 72.70%, and this economic benefit is highly significant. Additionally, the TRNSYS simulation software was used to model and optimize the control of the system.