Experimental Study On Thermal Conductivity Of Mwcnt/t-znow/pvb Composites

Energy shortage is becoming more and more serious.Developing renewable energy and getting rid of dependence on fossil energy are the fundamental way to solve the energy crisis.Solar energy photovoltaic power is a promising technology in the field of renewable energy.However,the efficiency of photoelectricity conversion is low,and improving the efficiency is one of the important research direction of Solar energy photovoltaic power.One of the factors that affect the efficiency of photovoltaic cells is that the heat dissipation performance of photovoltaic cells is poor,resulting in high temperature of the battery.Improving the thermal conductivity of the encapsulated film is beneficial to the heat dissipation of the photovoltaic cells.In this paper,MWCNT/T-ZnOw/PVB composite was made through incorporation of the MWCNT and T-ZnOw into PVB polymer matrix by means of solution blending.Transient electrothermal technology(TET)is applied to measure the thermal conductivity of composite.With the total mass fraction of MWCNT and T-ZnOw maintained at 1%,compositeswith ratios of 1:9,3:7,5:5,7:3,9:1 were prepared,and the thermal conductivity of the composite was measured.The results show that the proportion of MWCNT and T-ZnOw has a great influence on the thermal conductivity of the composite:with the increase of the mass of MWCNT,the thermal conductivity of the composite increases and then decreases.When the proportion of filler is 7:3,the thermal conductivity reaches the maximum value of 0.61 Wm-1k-1.The reason is that the two kinds of fillers form a heat conduction network in the matrix material by the unique shape structure.The heat conduction mechanism of the material changed from phonon heat conduction to the phonon heat conduction in the matrix and the electron heat conduction in the heat conduction network.thermal resistance method and effective medium approach is used to established the heat conduction model.When the proportion of MWCNT is small,the thermal conductivity model has a good fit with the experimental results.However,when the proportion of MWCNT is large,the thermal conductivity model is greatly different from the experimental results.The reason is that agglomeration occurs when the content of MWCNT is too large,and the thermal conductivity model is no longer applicableThe composite material was heated for 1 hour and the temperature was set at 80?,100?,120?,140?.The thermal conductivity of materials decreases first and then increases,reaching the lowest when the temperature is 100?.The heating temperature was set at 140? and the heating time was 1,2 and 4 hours respectively.After heating for 1 hour,the thermal conductivity of the material increased,but with the extension of heating time,the thermal conductivity of the material decreasedThe thermal conductivity of the composite decreases with the increase of illumination time after 10days,20days and 30 days of ultraviolet irradiation.The pure PVB material,the 1%T-ZnOw,the 1%MWCNT and the composites with a filler ratio of 7 to 3 were subjected to uv irradiation for 30 days respectively.The results show that ultraviolet light has the least effect on the thermal conductivity of the material containing 1%T-ZnOw and the most effect on the thermal conductivity of the pure PVB material.