| The heat pump is one of the most important energy-saving technology. Because of the outstanding advantages of high efficiency, easy operation and green environmental protection, the air source heat pump (ASHP) has a broad prospect of popularization and application instead of coal-fired boiler heating. However the traditional ASHP occurs a series of problems when it is run in low-temperature environment for a long time, based on this background, a new ASHP system with phase change heat storage evaporator has been developed and studied.Compared with the traditional ASHP, the new ASHP system with phase change heat storage evaporator increases a phase change heat storage device which can achieve the combination of the heat pump technology and the phase change heat storage technology.In this paper, the study has been carried out in different environment conditions and in three running modes:heating-heat storage, heating-heat release and defrostering-heat release. When the environmental temperature is higher than -5℃, the system is running in heating-heat storage mode, when the environment temperature is below than-5℃, the system is running in heating-heat release mode, when the environment temperature is lower, and the evaporator is frosting, the system is running in defrostering-heat release mode. The new developed ASHP has solved the contradiction between energy supply and energy demand which is existed in the traditional ASHP, and also the new developed ASHP can improve the security and economy of ASHP’s operation in low temperature remarkably, and it can accomplish the phase change heat storage defrosting efficiently and energy-saving at a high rate of speed.In order to study the characteristics of the performance of the new developed ASHP, a experimental prototype was designed and assembled, and a refrigeration storage was established to simulate the outdoor environment. The operating properties of the ASHP have been tested in different environment temperatures and different modes. The test results show that the new ASHP system has excellent performance in the three operating modes, the heating COPs of the system are 2.0 and 1.94 respectively in the ultra-low -25℃ and -30℃ temperature, and the heating capacity of the ASHP can meet the basic heating needs even in the ultra-low -30℃ temperature, the exhaust temperature of the compressor is reduced significantly. The experimental results indicate that the new ASHP system with phase change heat storage evaporator can solve the contradiction between energy supply and energy demand in the heating process, and can improve the performance of the ASHP in low-temperature greatly. The new ASHP can be applied to the vast northern region of lower ambient temperature. |
