Experimental And Simulation Study On Heat Transfer Performance Of Paraffin Single Tank Heat Storage System

The efficient utilization of solar energy is one of the main means to solve the problem of energy shortage and environmental pollution.Because of the intermittency and fluctuation of solar energy,the thermal storage system(TES)plays a vital role in the field of solar energy utilization.To further study the heat storage performance of the paraffinbased solar single-tank system and find a more suitable experimental configuration,as the basic research work,we established a single-tank heat storage experimental platform,using RT48 as the phase change material(PCM),using FLUENT software,based on simulation optimization analysis of the configuration of the heat storage device.To improve the heat storage and release rate of the phase change heat storage system,the group experiment and response surface method(RSM)were used to analyze the heat transfer enhancement effect of expanded graphite(EG)particles and copper bars with different proportions.Then the heat transfer performance of the single tank heat storage system with different taper tables and finned configuration is analyzed from the optimization of tank geometry and fin structure.Finally,combined with the practical engineering application,a single tank energy storage domestic hot water system using night valley power is designed,and the inlet conditions of heat transfer fluid(HTF)and the influence of horizontal and longitudinal cascade TES device are explored.The results show that the experimental results are in good agreement with the simulated data.The height-diameter ratio of the tank and the melting temperature of the paraffin has a great influence on the heat transfer effect,but the healing power has almost no influence when the total work is constant.RSM analysis and simulation results show that the best heat transfer enhancement effect is when the diameter of the copper rod and the mass fraction of EG graphite are 4 mm-6 mm and 2 wt.% respectively,and the best effect is when the copper fin is placed 100 mm away from the center of the tank.The truncated cone with a taper of 0.37 showed the best performance in the process of charging and discharging,and the effect of accelerating the phase transformation process was more obvious than that of a few long fins,and the heat transfer enhancement effect of the fin at the same position of-15° was the most obvious.Within the research range,0.8m /s is the most appropriate inlet flow rate for HTF,and the latent heat and heat release in radial cascade account for a larger proportion,and the effect is better.This study will provide theoretical guidance for the optimization design and practical application of the single-tank TES.