Application Mechanism And Experimental Study Of Phase Change Materials In Thermal Control System Of Solar Cell

In the solar photovoltaic power generation system,the increase in the operating temperature of the solar cell module is one of the important factors which leads to the reduction of the photovoltaic conversion efficiency and reduction of the system output power.Therefore,controlling the operating temperature of solar cells has become one of the key technologies for improving the output power of solar photovoltaic power generation systems in the process of solar photovoltaic power generation.Based on the basic structure of a photovoltaic/phase change material(PV/PCM)solar cell thermal control system,this paper develops the external and internal heat of the PV/PCM thermal control system through internal thermal conversion,transmission,and storage characteristics control theory research.The thermal control model of the PV/PCM system was established,and the influence of thermal properties of phase change materials on the thermal control performance of PV/PCM was analyzed using COMSOL software.In addition,an experimental prototype of PV/PCM solar cell thermal control system was designed to carry out experimental research on the effects of PCM thickness(mass),melting point temperature,and thermal conductivity on the solar cell thermal control characteristics.The following conclusions were obtained:(1)Based on the structure of the PV/PCM solar cell thermal control system,an external and internal thermal control model is established by analyzing the light-to-heat conversion,transmission,and storage control characteristics inside the system.Using COMSOL software,the PV/PCM thermal control model structure was designed,and the effects of PCM thickness(mass),melting point temperature,thermal conductivity,and latent heat value on the internal temperature distribution of the system were studied.The results show that during the same working time,in the PV/PCM model,the temperature near the back panel and the side of the solar cell is higher,and the temperature gradually decreases from the outside to the inside.The isothermal surface inside the PCM unit is distributed in a layered structure.The temperature difference from outside to inside(back)gradually becomes smaller.(2)Using the designed PV/PCM thermal control model and COMSOL software,the thermal properties of phase change materials(thermal conductivity,latent heat value and phase change temperature),PCM thickness(mass),and environmental meteorological conditions were used to analyze the solar cell thermal control characteristics affect research.The results show that the thermal properties of phase change materials directly affect the thermal control characteristics of solar cells in PV/PCM.Under certain conditions,the lower the melting point of the phase change material and the thermal conductivity of 1.1-1.3 W/(m·K)Within the range,the thermal control characteristics of PV/PCM are better.Moreover,there is a clear correlation between the influence of various design parameters on the thermal control characteristics of PV/PCM.Therefore,the optimization of PV/PCM thermal control system involves the collaborative design between the various parameters of the system.(3)Designed a PV/PCM thermal control experimental prototype,and used lauric acid-stearic acid-expansible graphite(LA-SA-EG)ternary composite phase change material to developed experimental study on the effects of different melting point temperature,hermal conductivity,PCM thickness(mass)of the phase change material on thermal control characteristic of solar cells.The results show that under the same conditions,in the prototype of the PV/PCM thermal control system with PCM thicknesses of 5cm,4cm and 3cm,compared with solar cells without phase change materials,the average of output power under the indoor simulated light source increased by 11.1%,9.3% and 6.3%.In the prototype of PV/PCM thermal control system with PCM peak melting point temperatures of 45.27 ?,47.38 ? and 63.79 ?,the average output power of solar cells compared with solar cells without phase change materials under indoor simulated light sources increased 8.76%,6.95% and 3.9%.In the prototype of PV/PCM thermal control system with PCM thermal conductivity of 1.1 W/(m·K),0.8 W/(m·K)and 0.4 W/(m·K),compared with solar cells without phase change materials,the average output power of indoor simulated light sources increased by 9.2%,6.5% and 4.1%.