A Novel solar-assisted air source heat pump system for urban renewal: Experimental test and numerical simulation

Old residential communities require novel heating solutions to meet heating demands sustainably. In Southern China, current heating systems in old communities have high energy costs and lack sustainability. A potential solution, air source heat pumps (ASHP), have evaporators susceptible to frost accumulation and poor heating performance at low ambient temperatures. This study proposes a hybrid design that uses additional solar thermal energy to improve energy gains from the air source; the innovative serial coupling design increases the air-source temperature by engineering the evaporator of the ASHP as the load-side of the heat exchanger. The novel hybrid design aims to be efficient, cost-effective, and sustainable, satisfying urban redevelopment needs. A prototype of the novel hybrid solar-assisted ASHP system was constructed; various performance parameters were evaluated, and system operation in extreme climates was simulated in TRNSYS. Results indicated that the novel hybrid system had significantly superior heating performance, delivering a 70.1% improvement in heating rate compared to single-source ASHP under lower ambient temperatures (13C). The novel hybrid system also had a high COP value between 5.7 and 6.3, significantly exceeding values of 2.3-3.5 for most air-conditioning units. It demonstrates consistent performance in all simulated climates. It is estimated that the novel hybrid system can save 1000 RMB in annual energy costs for an average Shanghai family and reduce Shanghais CO2 emissions by 4.7 million tons. The novel system addressed limitations of ASHP, optimizing performance while maintaining sustainability, offering a promising solution for urban renewal projects in China.