Investigation On Thermal Management Of Photovoltaic Panels Based On Form-stable Composite Phase Change Materials

With development of society,people's demand for electrical energy is getting higher and higher.However,traditional power generation methods will exacerbate global problems such as shortage of resources,environmental pollution,and ecological destruction.Therefore,development and utilization of photovoltaic power generation technology is particularly important for sustainable development of society.However,photovoltaic efficiency of widely used crystalline silicon photovoltaic panels is between 12%and 24%,and the rest solar energy is converted into heat energy,resulting in a rapid increase in the temperature of panels,which affects the photovoltaic efficiency and lifetime of panels.In order to effectively control the temperature of photovoltaic panels,this paper proposes a thermal management system for photovoltaic panels based on a form-stable composite phase change material(PCM).It can not only solve the problem of the decrease of photoelectric efficiency due to high temperature in the working process of photovoltaic panels,but also can compensate for the problem that active cooling technologies need to consume external energy and traditional passive heat dissipation technologies have low heat dissipation efficiency.In this work,a high thermal conductivity paraffin/expanded graphite form-stable composite PCM was prepared and a photovoltaic panel with integrated form-stable composite PCM(PV-PCM panel)was designed.A photovoltaic panel performance test system based on the form-stable composite PCM was established and the PV-PCM panel and a common photovoltaic panel(PV panel)were tested separately.Experimental results show that When average ambient temperature is 25°C and average irradiance is 654 w/m~2 with an average wind speed of 1 m/s,the maximum temperature difference between 1#-8#temperature measurement points on the back of the PV-PCM panel is 4°C lower than that of the common PV panel,which shows that the paraffin/expanded graphite composite PCM helps to improve uniformity of temperature distribution on the PV-PCM panel;The maximum temperature reached by the PV-PCM panel is 4.7°C lower than the common PV panel and the PV-PCM panel's temperature was maintained below 50°C for 3.33 h(200 min),2.43 h(146 min)longer than the common PV panel;Compared with the common PV panel,output power of the PV-PCM panel increases by an average of 2.02%and the instantaneous output power increases by a maximum of 11.50%,which shows that the thermal management system based on the form-stable composite PCM can effectively improve the electrical performance of a photovoltaic panel.In this work,a numerical model for heat transfer process of the PV-PCM panel was established.Effects of material forming density,ambient temperature and wind speed on the thermal management of the composite PCM were studied and numerical results were compared with the experimental results to verify reliability of the numerical model.The research found that average temperature variation curves of the PV-PCM panel obtained by experiment and simulation are basically the same with average relative error of 4.61%and the maximum relative error of 14.49%,indicating that the numerical model used in this work can be used to simulate the heat transfer process of the PV-PCM panel.The experimental results and numerical model in this paper have certain guiding significance for the design of similar PV-PCM panels and the selection of material forming density.