Simulation Of Thermal Energy Storage Heat Exchanger Used For Defrosting In Air Source Heat Pump

A Thermal Energy Storage Based Hot Gas Defrosting System for Air Source Heat Pump is a new system combinding technology of Defrosting System for Air Source Heat Pump with energy storage. An energy storage equipment of phase change is added to the system to store surplus heat when heap pump runs in high efficiency and the heat is used as low grade energy for defrost. Then the energy in the PCM is discharged in the hot gas defrost process. So the problems of the energy lacking for defrost or from mostly compressor are thoroughly solved.Firstly, the paper presents different mode flow of new system on basis of analyzing the characteristic of Defrosting System for Air Source Heat Pump (DSASHP). Then it supplies a physical model of phase change heat accumulator by analyzing and choosing PCM, and discusses energy consumption problem for DSASHP, then designes heat accumulator equipment with different PCM on basis of experiment data of defrosting energy consumption.Secondly, a mathematic model for heat-transfer process of phase change material in heat accumulator was developed based on enthalpy method and discreted with finite difference method, and solved by alternating direction implicit method and iteration method. Taking Na₂SO₄·10H₂O as phase change material, without regarding to heat dissipation, the process of thermal storage and release in heat accumulator was simulated.Eventually, the influence of inlet temperature, dryness fraction of the refrigerant, the configuration of heat accumulator and PCM on heat charge and discharge were analysed. Then heat accumulator was optimzed using the results.This paper gives reference to the matching of the parameters and the optimal design of the system, and supplies theory support and technology accumulation for its popularization and application.