Research On Convection Type Phase Change Energy Storage Heat Exchange Device Based On Solar Assisted Air Source Heat Pump

This paper mainly summarizes the research progress of air source heat pump technology,solar heat utilization technology and phase change energy storage technology in the field of building energy conservation,and proposes solar-assisted air source heat pump integrated system with convection phase change energy storage heat exchange device.The system integrates various energy-saving technologies,unifies the processes of cold storage,cold release,heat storage,and heat release.The system makes full use of renewable energy sources such as solar energy,air energy,etc.,which improves the rationality of the system's energy use,and can be effectively improve the low temperature adaptability of the air source heat pump.This paper describes and analyzes the eleven operating modes of the integrated system,and conducts simulation research on the two key components of the integrated system,convection type phase change energy storage heat exchanger and energy storage container.Firstly,the organic phase change material RT6 was determined.Based on the heat exchanger design principles and phase change energy storage theory,the dimensional parameters of the two were designed.Based on Solid Works software,a three-dimensional physical model was established.Then the phase change heat transfer theory and numerical calculation method are introduced in detail,and the theoretical model and solution method selected for the simulation study are determined.Based on the enthalpy method,their mathematical model was established,and the grid model was established based on ANSYS software,and Fluent software was used for simulation research.For the phase-change energy storage heat exchanger,the heat transfer and flow characteristics under variable temperature and variable flow conditions are mainly studied.If the inlet flow rate is too large,the material will flow out of the heat transfer tube before reaching the phase transition temperature(277K ? 279K);if the flow rate is too small,the convection effect will be weakened,and the significance of the convective phase change energy storage heat exchange device will be lost,and the optimal flow rate in the tube is 0.03m/s.In the phase transition interval,the pressure drop in the tube shows a downward trend with the increase of the liquid fraction.In order to save pumping energy consumption,the liquid phase rate threshold is considered to be 0.3.For the energy storage container,the effects of variable flow rate conditions on the cooling process and the effect of variable temperature conditions on the heat storage process are mainly studied.As the flow rate increases,the temperature difference between the supply and return water decreases,energy consumption increases,but the cooling efficiency increases.In order to obtain a larger temperature difference between the supply and return water,the flow rate must be reduced,which will lead to a reduction in cooling efficiency.It can be seen that in the process of cooling(heat storage),the energy consumption of the pump and the efficiency of cooling are a pair of mutually contradictory contradictions.In the actual project,their impact should be comprehensively considered to maximize the economic benefits.In this paper,through CFD numerical simulation,the phase change heat transfer characteristics of the convective phase change energy storage heat exchange device are analyzed,and the feasibility of its application to the system is verified.It provides a certain theoretical basis and help for the optimal design of the spiral tube heat exchanger and the spiral tube phase change energy storage container.