ABSTRACT

The turbulent convective thermal transfer in channel heat exchangers (CHEs) is studied numerically via the CFD (Computational Fluid Dynamics) method. Deflectors are inserted on the hot bottom walls of the heat channel to enhance the hydrothermal characteristics. Various shapes of in-line deflectors are considered, namely: rectangular (a/b = 0.00), cascaded rectangular-triangular (a/b = 0.25, 0.50, and 0.75), and triangular (a/b = 1.00) shapes. From the obtained results, the inclusion of in-line deflectors with a/b = 0.75 has given the most significant thermal enhancement factor, which was higher than that for a/b = 0.00, 0.25, 0.50, and 1.00 by about 5.36, 5.06, 67.27, and 3.88%, respectively. Also, the in-line cascaded deflector’ case (a/b = 0.75) shows an increase in the enhancement factor (η) from 4 to 15.44% over the cases of one deflector (corrugated, rectangular, triangular, trapezoidal, arc, (+), S, 45° V, 45° W, T, Γ, and ε-shaped) or two deflectors (staggered corrugated). This highlights the effectiveness of in-line cascaded rectangular-triangular deflectors with a/b = 0.75 in improving the performance of the proposed exchanger for the conditions adopted.

摘要

通过CFD（计算流体动力学）方法对通道换热器（CHE）中的湍流对流换热进行了数值研究。导流板插入热通道的热底壁上，以增强水热特性。考虑了各种形状的直列偏转器，即：矩形（a / b  = 0.00），级联矩形-三角形（a / b  = 0.25、0.50和0.75）和三角形（a / b  = 1.00）形状。从获得的结果来看，包含a / b  = 0.75的在线偏转器提供了最显着的热增强因子，该热增强因子高于a / b的热增强因子。 = 0.00、0.25、0.50和1.00分别约为5.36、5.06、67.27和3.88％。另外，在在线级联偏转器”的情况下（A / B  = 0.75）所示的增加增强因子（η超过一个偏转器的情况下从4）至15.44％（波纹状的，矩形的，三角形的，梯形的，圆弧，（ +），S，45°V，45°W，T，Γ和ε形）或两个导流板（交错的波纹状）。这突显了a / b  = 0.75的串联级联矩形-三角形偏转器在改进所采用条件下所建议的交换器性能方面的有效性。