Research On Application Of Nano-fluid Microchannel Heat Sink Cooling Fresnel CPVT System

In the operation of the concentrating photovoltaic system,it is usually accompanied by problems such as high temperature and long term thermal stress of the battery,resulting in a decrease in the electrical efficiency of the battery and may cause the battery to be abnormal or damaged.For point concentrating Fresnel CPVT systems,the cooling problem is particularly important due to the particularity of high-power concentrating and the application of very small volumes of gallium arsenide?Ga As?cells.In this paper,based on the point concentrating Fresnel CPVT system,it is proposed to use the straight-through microchannel heat sink to cool the battery chip and use the new material nanofluids to enhance heat transfer.The main research contents include:Preparation of Si O₂ and carbon tube nanofluids of different mass fraction by different method and study its basic properties of the law of change by experiment.The results show that the thermal conductivity of the Si O₂ nanofluids prepared by the dispersion of high pressure micro jet is higher than that of the Si O₂ nanometer fluid,which is only 2.89%,when the preparation of nano-fluid by ultrasonic crushing method,in a certain range with the ultrasonic vibration of the time,the nano-fluid particle size decreases,Zeta potential increases,thermal conductivity increases.The carbon tubes nanofluids with a concentration of 2%were increased by 10 m V and the thermal conductivity increased by 0.038 W/m·K after adding the dispersant.In this paper,the physical model of gallium arsenide battery is cooled by straight-through microchannel heat sink.The model is modeled by Ansys software and simulated,different heat exchanger are simulated and the parameters such as Nusselt number,heat transfer enhancement factor and field synergy theory are introduced to study on heat transfer enhancement.The results showed,when the nanofluids are used as heat transfer agents,the field synergy degree is better than that of water.The field synergy degree of carbon tube nanotubes is higher than that of Cu and Si O₂ nanofluids,when Re is 200,the field synergy angle of carbon tube,Cu and Si O₂ nanofluids are74.26°,82.85°,85.33°.The photoelectric conversion model of gallium arsenide battery chip was modeled and the hydrothermal performance of the system is calculated and analyzed by loading the Fresnel three condensed energy density.The results showed,the main factors affecting the electrical efficiency of the battery are the sun direct irradiance.The increase of the battery temperature will decrease the electrical efficiency,but the influence degree is small and the electrical efficiency temperature coefficient is only-0.01%/?.The simulation results of the thermal performance of the system are in good agreement with the measured results of the experimental system.The deviation of the cooling water temperature is within±5%.The Fresnel CPVT test system was constructed and the influencing factors of the system output characteristics were tested,experimental results showed DNI has a greater impact on the power of the CPVT system.At the same time,the increase of the incident angle reduces the system output power,the incident angle of 0°and 1°of two single solar cell CPVT system,real-time output power reduction of up to 6.35W.While,the factors such as the natural fouling and the assembly distance between the converging elements will have different effects on the output performance of the CPVT system,and the degree of influence increases with the increase of DNI.