Experimental And Numerical Study On Modular Phase Change Thermal Storage Electric Heating System

In recent years,the region of Northern China has caused serious environmental pollution problems due to coal-fired heating,making the call for promoting the "energy revolution" and "clean heating" growing.Electric energy is a kind of clean energy,and electric heating can effectively solve the pollution problem caused by coal burning.At the same time,due to the slow construction of the power grid in the northern region,the phenomenon of “wind power abandonment” has been caused.Phase change thermal storage electric heating can fully utilize excess electric energy under the premise of satisfying heating requirements,and can achieve the effect of “cutting peaks and filling valleys” on grid load.Under the condition of “high and low electricity price” policy,it can achieve economical purpose.This paper proposes a modular phase change thermal storage electric heating system,which can be combined with the building envelope structure and freely assembled according to the indoor heating area requirements.It is suitable for both the heating renovation for existing building and heating installation for new construction.The modular phase change thermal storage electric heating system is studied by the combination of experiment and simulation.In the experimental aspect,the experimental study of the heat storage characteristics of the modular phase change thermal storage electric heating system under different heat source power conditions is carried out.The experimental results show that the heating temperature of modular phase change thermal storage electric heating system is relatively stable in the 8-hour heating and 16-hour heat dissipation cycle.At the same time,the higher the power of heat source,the higher the heating temperature of the system,and the smaller the amplitude of the heating temperature,but the effect on the maximum heating temperature is not significant.Based on the phase change heat transfer theory and experimental tests,the mathematical physics model of the modular phase change thermal storage electric heating system is established based on the enthalpy method.The ANSYS software was used to simulate the heat storage characteristics of the modular phase change thermal storage electric heating system.The reliability of the established model and the correctness of the simulation results were verified by comparing the simulation results with experimental data.Based on the established model,the influencing factors of the heat storage characteristics of the modular phase change thermal storage electric heating system were analyzed.The results show that the characteristic parameters of the phase change heat storage module and the indoor environment have influence on the heat storage characteristics of the system.The thicker the phase change heat storage module is,the lower the heating temperature is,and the shorter the heat storage period of the system is;the higher the phase change temperature is,the higher the heating temperature of the system is;the smaller the phase change radius is,the more stable the heating temperature of the system is,and the shorter the heat storage period of the system is;The indoor temperature has little influence on the heating temperature of the system;the larger the convective heat transfer coefficient is,the lower the heating temperature is,and the heating temperature amplitude is basically unchanged.Finally,taking a heating room in Harbin as an example,the physical model and mathematical model of the room with modular phase change thermal storage electric heating system are established.The indoor temperature field,velocity field and PMV-PPD index of modular phase change thermal storage heating room are simulated and analyzed by ANSYS software.The results show that the indoor temperature distribution of the room with modular phase change thermal storage electric heating system is uniform.The indoor temperature can be maintained at the design temperature with 20°C.The indoor air velocity distribution is uniform,and the air velocity in most areas is less than 0.15m/s;indoor PMV values are evenly distributed,most of the time between-0.5 ~ +0.5.This paper provides a theoretical basis for the optimal design and popularization of modular phase change thermal storage electric heating system.