Hybrid thermal and optical modeling of a solar air heater with a non-flat plate absorber

Abstract

In this study, we developed a model based on a SAH. We can enhance air turbulence by creating a non-flat plate on a SAH absorber using a ratio of (e/H = 6), thereby increasing the solar collector’s convective heat transfer coefficient, Nusselt number, and thermal performance. A validation experiment was conducted to determine the accuracy of the developed model. Ray tracing and FEM simulation techniques were used to analyze the optical and thermal properties of the system simultaneously. Various operational and structural conditions were applied to analyze the system’s thermal performance under inhomogeneous heat flux on the absorber’s surface. The data demonstrate that non-flat plate surfaces contribute to wall-induced turbulence, which affects air temperatures. Outcomes demonstrate that mass flow rate excessively affects thermal efficiency, useful energy, and outlet temperatures. Thus, when the inlet air flow rate increases from 0.02 to 0.06 kg/s, the average hot air temperature at the SAC outlet during the daytime reduces from 55.6 to 47.82 °C, applicable heat energy increase from 646.5 to 970 W, and the average thermal efficiency increased from 28.8 to 54.7 %. Instantaneous non-flat absorber plates increased average thermal efficiency and heat transfer coefficient (h) to 9.10 and 27.24 % compared with flat plate absorbers (e/H = 1) at the same mass flow rate (0.05 kg/s). The highest Nusselt number increase observed during the day is 141.5% for non-flat plate compared to flat plates.