The main idea comes from the fact that waste heat generated by the radiating combustion exhaust gas can be recovered by a plate heat exchanger to heat the air flow utilized in different applications. The main contribution of this study is to verify the effect of hot gas radiation and the inclination angle on the performance of plate heat exchangers. For this purpose, two counter-current flows of hot radiating exhaust gas and cold air separated with a conducting wall as the basis of a gas-to-gas plate heat exchanger (PHE) is numerically simulated in the transient period. In the gas domain, the combination of continuity and momentum equations are solved in the transient period up to the steady-state condition. The dimensionless form of the governing equations are solved simultaneously using the finite-difference method (FDM) and the Blocked-off technique, while the discrete ordinate method (DOM) is used to solve the radiative transfer equation (RTE) in the participating gas media. The results reveal that the gas radiation has a major role on the rate of heat transfer, such that by increasing the optical thickness from small to large values, a sweep behavior can be observed in the thermal performance of PHE. Furthermore, the rate of heat transfer increases significantly by increasing the radiation-conduction (RC) parameter, while the radiative effects of the hot flue gas on the pressure drop can be neglected without loss of accuracy. Moreover, the rate of heat transfer is not significantly affected by the inclination angle.

中文翻译：

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利用板式换热器辐射废气流回收的废热加热空气的数值模拟


主要思想来自这样一个事实：辐射燃烧废气产生的废热可以通过板式热交换器回收，以加热不同应用中使用的气流。这项研究的主要贡献是验证热气辐射和倾角对板式换热器性能的影响。为此，在瞬态期间对作为气-气板式换热器（PHE）基础的热辐射废气和冷空气的两种逆流流动进行数值模拟。在气体域中，连续性和动量方程的组合在瞬态期直至稳态条件下求解。使用有限差分法 (FDM) 和 Blocked-off 技术同时求解控制方程的无量纲形式，同时使用离散坐标法 (DOM) 求解参与气体介质中的辐射传递方程 (RTE) 。结果表明，气体辐射对传热速率起着重要作用，因此通过将光学厚度从小值增加到大值，可以在板式换热器的热性能中观察到扫频行为。此外，通过增加辐射传导（RC）参数，传热速率显着增加，而热烟气对压降的辐射影响可以忽略不计，而不会损失精度。此外，热传递速率不受倾斜角度的显着影响。