Numerical simulation study for impinging jet solar air heater
In order to enhance the performance of solar air heaters,this study establishes a mathematical model for air jet solar air heaters and analyzes the influence of air jets on the performance of solar air heaters.The results indicate that by incorporating baffle plates inside the solar air heater to induce jet flow,not only the flow velocity near the wall of the absorber plate can be increased,but also the velocity gradient perpendicular to the direction of airflow can be reduced.The jet flow optimizes the velocity distribution within the duct,thereby effectively improving the convective heat transfer coefficient between the air and the absorber plate.Compared to conventional solar air heaters,air jet solar air heaters exhibit significantly higher thermal efficiency.When the inlet velocity increases from 0.5 m/s to 3.0 m/s,the difference in thermal efficiency between the two types increases from 5.01%to 15.38%.However,air jet solar air heaters suffer from relatively high pressure losses,resulting in a declining trend in effective efficiency as the air flow rate increases.At an inlet velocity of 2.5 m/s,the effective collection efficiency of jet solar air heater reaches a maximum efficiency of 63.75%,representing an improvement of 11.21%compared to conventional solar air heaters.To sum up,the use of baffles to form air jets could significantly improve the heat collection efficiency of solar air heaters.
air jetsolar air heatercollection efficiencypressure loss
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