| Solar energy is one of the cleanest and most potential energy sources currently known.While concentrating photovoltaics make full use of solar energy,they also face problems such as low comprehensive energy utilization efficiency and high temperature.In order to improve comprehensive energy utilization efficiency and reduce battery temperature,this paper uses phase-change heat storage heat sinks with high thermal conductivity and thermoelectric devices and designed solar concentrating photovoltaic-thermoelectric coupling system.Due to the low thermal conductivity of paraffin materials,a composite phase change material with good thermal conductivity has been developed in this paper by using branched electrolytic copper powder and expanded graphite(EG)with high thermal conductivity.By observing the combination of the thermal conductive material and the paraffin substrate,the surface morphology and thermal stability of the structure after molding,it is found that increasing the content of expanded graphite can increase the porosity and improve the internal temperature uniformity.However,the 6%EG and the 2.5mm compact composite material leaked seriously.In addition,the thermal performance of expanded graphite content and copper powder content under different ratios was investigated through heat storage and release experiments,and it was found that the effect was best when 10%EG and EG:Cu=1:1.This paper designs heart-shaped,sunflower,and sub-type structures according to the thermal diffusion mechanism of the photovoltaic cell on the phase change heat sink.In this paper,a thermal conductivity test device is built to study the thermal conductivity of the composite phase change material and the phase change heat sink.The effects of sprayed graphite content,thermal conductivity material combination method,copper powder percentage,sample thickness on the thermal conductivity of the composite phase change material after pressing were studied.It is found that adding expanded graphite and copper powder can greatly increase the thermal conductivity of the composite phase change material and the thermal conductivity of EG:Cu=1:1 is as high as 5.136W/(K·m2).Compared with the cavity structure,the phase change heat sink designed by the diffusion structure has a better effect,and the temperature control effect of the heart-shaped structure is the best,which is 6.1 times of the cavity structure.This paper designs a micro-channel radiator with a cross-sectional shape of "Ω",and a comprehensive energy utilization system.The effects of flow rate,composite phase change material,phase change heat sink substrate and PCM thickness on the thermoelectric performance of the system were compared by experiments.Experiments have found that the composite phase change heat storage material after adding copper powder has the greatest impact and the temperature of the bottom surface of PV cell(Td)can be reduced to within 105.8℃ under the heating power of 90W.The flow factor has the least influence.The phase change heat storage heat sink designed by the thermal diffusion method can make the system temperature lower and the temperature distribution uniform.At the heating power of 90W,the temperature of Td can be maintained below 120℃.With the increase of the thickness of the phase change heat sink,the effect is better and the system temperature is more stable.In this paper,an outdoor solar concentrating photovoltaic-thermoelectric coupling system is built,and the effects of coupling mode,concentration ratio,phase change heat sink thickness,and phase change heat sink substrate structure on the thermoelectric performance of the system are studied through experiments.It is found that the CPV/T system can minimize the PV temperature(about within 30℃),and the CPV/PCM/TEG/T system has the best comprehensive thermoelectric performance.At the same time,the thermally diffusible phase change heat sink substrate has stronger thermal conductivity,lower temperature,and the best heart-shaped structure than the broken line and cavity structure.In addition,a too low concentration ratio will result in a decrease in the average power generation of TEG Enlarging the size of the phase change heat sink can increase the energy efficiency of the system. |
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