Study On Flow And Heat Transfer Characterizations Of Micro-jet Heat Sink Based On Conceutratung Solar Cell Cooling

With the global energy resources becoming increasingly tense and the use of traditional fossil fuels causing a series of environmental problems,Solar energy,as one of the important renewable resources,its efficient use plays an important role in the development of the national economy.Concentrating Photovoltaic（CPV）power generation technology has attracted much attention as a way to make efficiently use solar energy resources.Aiming at the problem of heat-induced failure of solar cells at high heat flux,a matrix microjet heat sink with return channel structure was designed in this paper.The flow and heat transfer characteristics of microjet heat sink were numerically simulated by using computational fluid dynamics（CFD）software.And related experiments were carried out by setting up an experimental platform.The structure of the microjet heat sink was optimized in the study,and evaluated the performance parameters.In the CFD numerical simulation,the three-dimensional physical and mathematical model of the microjet heat sink were established.Using the control variable method,the number of return channels,the distribution position of the return holes,the jet Reynolds number,the ratio of the distance between the microjet and the cooled surface to the diameter of the microjet heat sink（H/d）,and input heat flux Q on the heat transfer and flow characteristics of the microjet heat sink was studied.The results show that: under steady-state conditions,the microjet heat sink with 49 return channels has better heat transfer performance than the 25 return channel at the Reynolds number 4600≤Re_a≤6663 of the jet,and when the return channel are distributed around the jet holes,it can effectively weaken the wall-attached lateral flow in the microjet heat sink on the jet state of the microjet fluid and significantly improves the heat transfer capacity of the microjet heat sink;With the gas Rea continues to increase,the average temperature of the cooled surface in the microjet heat sink gradually decreases;when the number of return channels is unchanged,the smaller H/d,the better the heat sink heat transfer performance;Q has little influence on the microjet heat sink performance,and only affects the average temperature of the cooled surface,which can be neglected;The overall pressure loss of the microjet heat sink system gradually increases with the increasing jet Reynolds number.The experimental platform of the microjet heat sink heat transfer system was built to carry out experimental research on heat transfer and flow state of heat sink.The test system is composed of air compressor,constant temperature water bath box,data acquisition instrument and microjet heat sink,etc.,which ensures the scientificity of the test system.The experimental results show that the number of return channels,,Re_a,H/d are the main factors affecting the performance of the microjet heat sink.When the microjet heat sink structure is constant,the average heat transfer coefficient and the average Nusselt number of the cooled surface increase with the increase of Rea;Under the same experimental conditions,the smaller the microjet heat sink of H/d,the larger （?） and （?）.The thermal resistance of the microjet heat sink R_ab decreases gradually with the increase of Re_a;As the H/d of the heat sink increases,the system pressure loss ΔP gradually increases,and the energy efficiency ratio EER increases.Through numerical simulation and experimental research,it is found that when the number of return channels is 49,4600≤Rea≤6663,4≤H/d≤10,and the heat flux density of the heat exchange surface is 4.22W/cm² ～ 10.0W cm²,The pressure loss is 13.05 ～ 133.45 k Pa,the thermal resistance is about 0.4K/W ～ 1.6K/W,and the energy efficiency ratio EER value is between 0.04～1.35.When the microjet heat sink with 49 return channels and H/d = 4,Rea = 6663,the temperature of jet air is 21℃,heat flux is 4.22W/cm²,the average heat transfer coefficient is （?）=6567.38 W/（m²·K）,average temperature of the cooled surface is （?） =29.59℃,these parameters are very beneficial to ensure the service life and photoelectric performance of concentrated solar cells.