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Summary: This thesis investigates a novel solar‐assisted heat pump integrated phase change energy storage system. The defrosting performance of this system was studied experimentally and the results were compared with two traditionally used methods: reverse cycle defrosting (RCD) method and hot gas bypass defrosting (HGBD) method. The results show that the phase change energy storage system has superior performance compared with traditional defrosting methods. The indoor temperature drop recorded was relatively small and the defrosting time was 75% of the RCD system and 53% of HGBD system. The phase change energy storage system increased the condensation temperature which consequently increased the temperature difference of heat transfer resulting in higher conductivity in the defrosting progress. Compared with the method of RCD and the method of HGBD, the recovery time of the system was shortened by 90 and 160 seconds, respectively. The system works with low‐temperature heat source and circulating water, which considerably reduces energy consumption, thereby improving the performance of the defrosting system. A further experimental study was also conducted on the heating performance and the results also indicated that the value of COP can reach up to 3.6 in daytime, and the indoor temperature can be stably maintained above 18°C throughout the day. Novelty Statement: A new defrosting method for energy storage defrosting is proposed, and the defrosting performance is compared with two common defrosting methods. In addition, the performances of the heating system over the day were experimentally investigated. The experimental results show the system meets the heating needs of the building. Finally, the influence of the outdoor temperature on the exergy efficiency of the system was discussed. It shows that this system can improve the operational stability, the system economy and energy saving. [ABSTRACT FROM AUTHOR]

A solar air-source heat pump system with phase change energy storage is investigated in this paper. By employing phase change storage in this system, it overcomes the frosting problem in the evaporator and improves the COP of heat pump under the extreme weather condition. The system is constructed and the experiment is carried out in Shijiazhuang. The testing results reveal that the average COP of the heat pump is around 4.92 in the clear days, 1.79 in extreme weather conditions, and 2.12 in the rainy or snow days, which is much higher than the traditional heating mode. Through economic analysis, it is found that the operating cost of the whole heating season is around 22.5% of the oil-fired boiler, 55.4% of the gas boiler, 27.1% of the electric boiler, and 65.6% of the air source heat pump. With the help of phase change storage, solar energy and air source can be utilized to the maximum extent to achieve the purpose of energy-saving and emission reduction in the extremely cold area. [ABSTRACT FROM AUTHOR]