In the present work, heat transfer and fluid flow characteristics for both Newtonian and non-Newtonian fluids in tube-in-tube helical coil (TTHC) heat exchangers have been investigated numerically. The various TTHC heat exchanger configurations studied are (1) parallel and (2) counter flow, with and without baffles. The power law index (n) and Dean number (N_De) are varied from 0.5 to 1.25 and 50 to 500, respectively. Further, two different models have been proposed to predict the friction factor (f) and Nusselt number (Nu) in TTHC. It is observed that f and Nu in the TTHC heat exchanger with baffles in the annulus is higher as compared to without baffles. Furthermore, at low Prandtl number the baffles have significant influence on heat transfer, while at high Prandtl number flow configuration has high significance.

中文翻译：

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管内螺旋螺旋换热器中牛顿和非牛顿流体的传热和流体流动特性

在目前的工作中，已经对管内螺旋螺旋管（TTHC）换热器中的牛顿流体和非牛顿流体的传热和流体流动特性进行了数值研究。研究的各种TTHC热交换器配置为（1）平行和（2）带有和不带有挡板的逆流。幂律指数（n）和迪恩数（N _De）分别从0.5到1.25和50到500不等。此外，已经提出了两种不同的模型来预测TTHC中的摩擦系数（f）和Nusselt数（Nu）。观察到f和Nu与没有挡板的情况相比，在带环状挡板的TTHC换热器中的温度更高。此外，在低普朗特数下，折流板对传热有显着影响，而在高普朗特数下，流动构型具有重要意义。