Research On Photovoltaic Thermal Management Performance Based On Eutectic Composite Phase Change Material

In the context of today’s energy shortage and increasingly serious environmental pollution,the vigorous development of new energy sources has become an important part of China’s sustainable energy development strategy.Solar energy,as an ideal new energy source with abundant reserves and no pollution,can be converted into various forms of energy through certain technologies,among which solar power generation technology is highly favored.Solar panels(PV)are important equipment for converting solar energy into electrical energy,however,the operation of solar panels involves heat absorption and warming at the working end,which restricts their photoelectric conversion efficiency.Phase change temperature control technology uses phase change materials(PCM)to store or emit thermal energy during the solid-liquid phase change process,thus achieving the purpose of adjusting and controlling the temperature at the working end.The application of PCMs in solar panels can provide efficient,smooth and suitable working-side temperature control solutions to improve photovoltaic conversion efficiency and extend service life.Based on this,this study is devoted to the design of a new solar panel based on eutectic composite phase change materials.The research work involves the efficient screening,sizing composite and application evaluation of eutectic phase change materials,which in turn promotes the application of phase change materials in photovoltaic thermal management systems.The specific work is as follows:Firstly,this study aims to design a binary eutectic phase change material with high latent heat value in the phase change temperature range of 40～45°C under the guidance of eutectic phase change material prediction method and the climate conditions of Guangzhou City,the experimental site.Four organic phase change materials,namely lauric acid,palmitic acid,myristic acid and hexadecanol,were selected as raw materials,and six different eutectic schemes were developed.The eutectic points and material ratios of each scheme were calculated by the eutectic point prediction method of eutectic phase change materials,and then DSC tests were performed to verify the eutectic phase change material with the mass ratio of hexadecanol to palmitic acid of 7:3.The latent heat of phase change of this eutectic phase change material is 221.1k J/kg,and the phase change temperature is 44.6℃.After that,in order to make the produced eutectic phase change material can be better applied in the system,the eutectic phase change material was compounded by using expanded graphite to prepare a hexadecanol-palmitic acid/expanded graphite eutectic composite phase change material.This step can not only improve the defect of organic phase change materials with low thermal conductivity,but also solve the leakage problem when phase change materials undergo phase change.The optimal addition amount of expanded graphite was determined to be 15% by leakage test,and then the properties of the eutectic composite phase change material were characterized by BET test,SEM test,FT-IR test,DSC test,specific heat capacity test,thermal conductivity test,phase change cycling test and thermal stability test,and the results showed that the eutectic composite phase change material of hexadecanol-palmitic acid/expanded graphite had a suitable phase change temperature(43.2°C),high latent heat of phase change(182.3k J/kg),high specific heat capacity and thermal conductivity,and high stability.Finally,a simple solar panel thermal management device was fabricated based on the preparation of hexadecanol-palmitic acid/expanded graphite eutectic composite phase change material.The photovoltaic-phase change material(PV-PCM)panel and the ordinary panel were subjected to control experiments,and the DC circuit was connected separately and operated under outdoor environment for 7 hours to test and record the changes of temperature,output voltage and power of the two panels.The results show that the eutectic composite phase change material can effectively improve the temperature distribution uniformity of the panels,reduce the peak temperature of the panels by 6.8℃,and increase the average output voltage by 0.61 V and the average output power by 4%.In summary,the hexadecanol-palmitic acid/expanded graphite eutectic composite phase change material prepared in this study can well meet the needs of thermal management of solar panels,improve the electrical performance of panels,and provide a certain reference value for heat dissipation research of solar panels.