Application of exergy destruction minimization in convective heat transfer optimization for elliptical tube

doi:10.11949/j.issn.0438-1157.20160544

Abstract

Abstract:

The expression of local exergy destruction rate is deduced on the analysis of convective heat transfer. Lagrange function is constructed with local exergy destruction rate set as optimization objective and prescribe flow power consumption as constraint condition. Besides, energy and mass conservation laws are taken into consideration in this Lagrange function. By taking variation on the Lagrange function, optimization equations are obtained. Through numerical simulation, the optimization equations are solved in the convective heat transfer for elliptical tube flow and the optimized velocity and temperature fields are obtained. The results show that the optimum flow structure in the elliptical tube is longitudinal swirl flow with multi-vortexes. Compared with the elliptical tube with general governing equations (Navier-Stokes equations), the optimized flow has a good heat transfer rate with low increase of flow resistance and the comprehensive performance, (Nu/Nu_s)/(f/f_s), is 3.21. Furthermore, the distribution of vortexes in the elliptical tube is also obtained which is significant to improve the design of elliptical tubes.

Key words: exergy, convection, heat transfer, optimization, elliptical tube, numerical simulation

摘要：

在流体对流换热分析的基础上得到局部?损率的表达式，以局部?损率为优化目标，满足能量与质量守恒条件，在流动功耗为定值条件下，根据拉格朗日泛函极值原理得到?损为极值时的控制方程组，发展了最小?损优化方法。将该方法应用到椭圆换热单管中，得到优化后的速度场与温度场。优化结果表明，优化流动结构为纵向旋流，具有较好的传热及流动性能，相比未优化椭圆管综合换热性能（Nu/Nu_s）/（f/f_s）可达3.21，同时得到了纵向涡在流场中的分布情况，这对椭圆管内强化换热发展具有指导意义。

关键词: ?, 对流, 传热, 优化, 椭圆管, 数值模拟

CLC Number:

TK124

WANG Junbo, XIE Pan, LIU Zhichun, LIU Wei. Application of exergy destruction minimization in convective heat transfer optimization for elliptical tube[J]. CIESC Journal, 2016, 67(S1): 307-311.

王俊博, 谢攀, 刘志春, 刘伟. 最小?损优化方法在椭圆换热管内的应用[J]. 化工学报, 2016, 67(S1): 307-311.

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