Abstract The research tries to apply a fuzzy logic approach to approximate the airflow thermal characteristic and flow friction for the turbulent regime in a heat exchanger equipped by diamond-shaped (D-shape) turbulators with arrangements in tandem. The variables studied in the work are Reynolds number within the range of 3500 to 16,500, three cone angles (θ), and three tail length ratios (TR). The heat transfer and pressure loss increased by increasing and decreasing the cone angle and tail length ratio, respectively. Investigation of the fuzzy logic model indicated that it is a powerful method to estimate the thermal characteristic and flow friction in the system. The accuracy of the fuzzy model was investigated and the mean relative errors (MREs) of 0.61% and 0.79% were calculated for predicting the Nusselt number and friction factor, respectively. In this study, the previous empirical correlations are corrected and new correlations are presented with higher accuracy. The constants of the equations were modified using the genetic algorithm. The prediction accuracy of the empirical correlations was increased especially for the Nusselt number. The errors of the FL model were compared with empirical correlations, which indicated the superiority of the fuzzy model.

中文翻译：

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菱形湍流器上湍流气流热摩擦特性的模糊逻辑

摘要 本研究试图应用模糊逻辑方法来近似在配备串联排列的菱形（D 形）湍流器的热交换器中湍流状态下的气流热特性和流动摩擦。工作中研究的变量是 3500 到 16,500 范围内的雷诺数、三个锥角 (θ) 和三个尾长比 (TR)。分别通过增加和减少锥角和尾长比来增加传热和压力损失。模糊逻辑模型的研究表明，它是一种有效的方法来估计系统中的热特性和流动摩擦。研究了模糊模型的准确性，并计算了 0.61% 和 0.79% 的平均相对误差 (MRE)，用于预测努塞尔数和摩擦系数，分别。在这项研究中，以前的经验相关性得到了纠正，新的相关性以更高的精度呈现。使用遗传算法修改方程的常数。经验相关性的预测精度提高了，尤其是对于 Nusselt 数。将FL模型的误差与经验相关性进行比较，表明模糊模型的优越性。