Research On The Heat Dissipation Performance Of Graphene/paraffin Phase Change Materials For Photovoltaic Panels

In view of the current photovoltaic panel photoelectric conversion efficiency is affected by its surface temperature,this paper prepared graphene/paraffin through experiments and carried out thermophysical characterization.According to the thermophysical characterization results,appropriate graphene/paraffin was selected for the heat dissipation of photovoltaic panels.The phase transition,structure and thermal conductivity characteristics of paraffin wax and graphene/paraffin wax investigated by means of molecular dynamics simulation methods combined with the experimental results and problems of thermophysical characterization.The main research work and conclusions are as follows:1.A heat dissipation experiment platform for photovoltaic panels was built.According to the average temperature of the photovoltaic panels using natural convection heat dissipation under different radiation intensities,the thermal properties of different phase change materials were compared and analyzed,and the melting point was selected from 42°C to 44°C paraffin wax is used to dissipate heat from photovoltaic panels.2.Graphene/paraffin composite phase change materials with different graphene mass fractions were prepared by melt blending method and thermophysical properties were characterized,and appropriate composite phase change materials were selected for the heat dissipation experiment of photovoltaic panels.The results show that the graphene and paraffin have good physical fusion without chemical reaction in the composite prepared by melt blending.Graphene/paraffin composites have good thermal stability at room temperature.Compared with pure paraffin,the thermal conductivity of graphene/paraffin composites was significantly improved,but the latent heat of phase change decreased with the increase of graphene mass.The graphene/paraffin composite phase change material with a graphene mass fraction of 2% has high thermal conductivity and phase change latent heat,and is an ideal composite phase change material for heat dissipation of photovoltaic panels.Compared with the natural air heat dissipation method,the heat dissipation performance of the paraffin phase change material is better.Compared with the heat dissipation method of the paraffin phase change material,the heat dissipation performance of the graphene(2%)/paraffin composite phase change material is better.3.Molecular dynamics method was used to explore the graphene/paraffin phase transition,structure and thermal conductivity characteristics of randomly dispersed and oriented graphene.The results show that: at low temperature,the force exerted by graphene carbon atoms on each atom of paraffin causes the paraffin molecules to solidify on the vertical line perpendicular to the graphene plane,forming the crystallization layer.When the temperature rises,the paraffin molecules melt from the outside to the inside,and when the temperature drops,the paraffin molecules solidify from the inside to the outside.Graphene promoted the crystallization of paraffin molecules and improved the thermal stability of paraffin molecules,resulting in lower latent heat of graphene/paraffin phase transition than theoretical calculation.Relative to the paraffin wax,graphene/paraffin thermal conductivity has a lot of ascension,as the temperature increased from 280 K to 350 K,graphene randomly dispersed and directional orientation of graphene/paraffin thermal conductivity of the paraffin thermal conductivity increased by 30% to 313% and 215% to 540%,compared with the random dispersion of graphene graphene/paraffin wax,directional graphene graphene/paraffin thermal conductivity increased by 38% to 163%;The high thermal conductivity of graphene/paraffin is attributed to the heat transfer promoted by the overlap of the paraffin molecules and graphene phonons.Graphene and paraffin in graphene-oriented graphene/paraffin have higher phonon overlap and therefore higher thermal conductivity compared to graphene-randomly dispersed graphene/paraffin.