Study On Application Of Phase Change Thermal In Solar Energy Heat Pump Heating System

With the development of solar energy heat pump heating technology, a growing number of research has been put into heat storage technology of solar energy heat pump system. In this paper, All components of solar heat pump with phase change thermal storage heating system is researched on theory, simulation and experiment. The following main areas are researched:the storage/exothermic chemical characteristics of PCMs and phase change heat storage device, energy transformation of solar heat pump with phase change thermal storage heating system, and the influence on heat pump performance with/without PCMs.Based on the fluent software, simulation is made to storage/exothermic chemical process of cylindrical PCMs.Following aspects are discussed:under constant wall temperature, changes of heat storage/exothermic time with different radius of PCMs.Changes of temperature of PCMs and water around it with different spaces between PCMs when the water and PCMs coupling. Factors which influence exothermic performance of phase change heat storage device is also researched.The simulation results show that:with the increase of diameter, heat storage/exothermic time of PCMs extend.So, in order to make full use of latent energy of PCMs,it is better to minimize the diameter.With the increase of space between PCMs, temperature of water around PCMs rise more quickly.In phase change heat storage device, There are many factors which influence exothermic performance of phase change heat storage device. When PCMs and hot media are chosen, the main factors are shape and size of PCMs and flow velocity of water.With the increase of diameter and the reduction of flow velocity, the heat exothermic time is extend. Conversely, shorten.To sum up, the determination of diameter of PCMs should be according to the actual situation.Both make full use of latent energy of PCMs and ensure the exothermic time.In Trnsys platform, model of solar heat pump with phase change thermal storage heating system is established and simulation is made. Collecting capacity and useful energy gain of solar energy collector, phase change heat storage, electricity auxiliary heating, energy from source and to load of heat pump, efficiency of collector and COP of heat pump and the whole system are computed in the typical day of Taiyuan.All above-mentioned energy are also simulated and computed in each month of heating period and the whole period.Compare the results which with PCMs and without PCMs. The results shows that:the use of PCMs has a lower influence in the average COP of heat pump during the heating process, but it is obvious to increase the average efficiency of collector and store energy.During heating period, the pump during the heating process, but it is obvious to increase the average efficiency of collector and store energy.During heating period, the COP of system is improved by0.38, and energy which PCMs stored is2.64%of useful energy gain of collector。11.34%electricity is also saved during heating period.The use of PCMs has the function of energy conservation and emission reduction.Experimental platform of solar heat pump with phase change thermal storage heating system is constructed.Following experiments is performed:solar energy storage experiment with PCMs, comparison of exothermic process experiment of sensible heat tank and latent heat tank, heat pump heating experiment with sensible heat tank and latent heat tank.The results show that the solidification process can delay the temperature drop of latent heat tank exit.During the experimental process, compare to the heat pump with sensible heat tank, COP of heat pump with latent heat tank is improved by21.6%.