Study Of Heat Dissipation For Concentrating Photovoltaic Cells With Multi-channel Manifold

Solar energy is the most abundant energy on the earth,and photovoltaic cells can directly convert sunlight into electricity.However,the power generation efficiency is limited by the photovoltaic temperature.If the photovoltaic is not effectively cooled,the high temperature will reduce the efficiency and shorten the life of the photovoltaic,and even cause damage to the photovoltaic cell due to overheating.At present,the main problems for the heat sinks are insufficient heat dissipation and uneven heat distribution.In order to solve these problems,this paper designed a novel multi-channel manifold for the heat dissipation of the densely packed concentrated photovoltaic cells.The mathematical models for calculating direct solar irradiance in Shenzhen were established based on the geographical location and seasonal variation characteristics of Shenzhen City.And the energy balance equation of photovoltaic system was also established to evaluate the energy transfer mechanism in the system.In order to improve the flow distribution uniformity and reduce consumption of pumping power,the dimensions of tree-shape manifold channel were designed based on entropy-generation minimization.According to the difference of the cross-sections of the channels,the researcher designed two kinds of manifold channel structures,which were manifolds with square cross-section and with rectangular cross-section in each stage,respectively.The fluid distribution uniformity and pressure drop of the manifolds which could be influenced by channel structure,channel length,flow rate and Reynolds number were analyzed by using CFD simulation.The channel structure and design parameters contributing to the best distribution uniformity were selected to design heat sink manifold.The heat dissipation for densely packed photovoltaic cell array with concentration rate of 500 by using the manifold channel was investigated in this paper to improve the power generation efficiency of the cell array.Each group channel network including two identical cooling manifolds with coolant flowing in counter directions were proposed to avoid the uneven temperature distribution along the flow direction.The heat dissipation ability and consumption of pumping power of the five-stage channel network regarding to the cooling fluid medium,inlet velocity and influence of the season was researched.Moreover,two different cooling devices with diverse channel dimensions were also compared in regarding with the cooling ability and consumption of pumping power.The design of the heat sink in this paper puts forward a new idea for the heat dissipation of the photovoltaic system,and the simulation results can be used to guide the engineering application.The solar irradiance is various in a day.This paper also conducted an analysis for the heat dissipation performance of the manifold from the sunrise to the sunset.The UDF source code was compiled to customize the heat source in order to have a real-time analysis for the heat sink.The effect of solar irradiance on the cell temperature,cell efficiency,pressure drop and consumption of pumping power was evaluated.The results of our study can be of practical significance in engineering.