Convective heat transfer optimization in a circular tube based on local exergy destruction minimization
Convective heat transfer optimization in a circular tube based on local exergy destruction minimization
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DOI：
10.1016/j.ijheatmasstransfer.2015.06.031
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发表时间：
2015-11
影响因子：
5.2
通讯作者：
Junbo Wang;Zhichun Liu;Fang Yuan;Wei Liu;Gang Chen
中科院分区：
文献类型：
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作者：
Junbo Wang;Zhichun Liu;Fang Yuan;Wei Liu;Gang Chen
本研究确定了揭示可用电势与局部火用破坏率关系的可用电势平衡方程，并给出了可用电势与局部火用破坏率的表达式。为了改善强化传热、降低流阻增大幅度，相对于基于表面的强化传热，提出了一种基于流体的强化传热方法。采用构造拉格朗日函数的优化数学模型来验证该方法，该拉格朗日函数的火用破坏对应于传热过程的不可逆损失，流体功率消耗对应于流体的流动损失。为了获得管内最佳的流动结构，管内流动被分为两部分：核心流动和边界流动。为了减少核心流中的不可逆损失，我们以流体火用破坏为优化目标，并指定流体功率消耗。为了降低边界流中的流动阻力，我们以流体功率消耗为优化目标，并规定流体火用破坏。推导了层流对流换热的优化方程，并进行了数值求解。在不同的参数下发现管内的纵向旋流。优化后的流动中，传热大大增强，同时流动阻力略有增加。综合性能，即传热与流动阻力的增加比，优化后达到3.65。
In this study, the equilibrium equation of available potential, which reveals the relation of available potential and local exergy destruction rate, is determined, and the expressions of available potential and local exergy destruction rate are given. To improve heat transfer enhancement and reduce increase amplitude of flow resistance, a method termed as fluid-based heat transfer enhancement is proposed relative to surface-based heat transfer enhancement. An optimal mathematical model by constructing Lagrange function with exergy destruction corresponding to irreversibility loss of heat transfer process and fluid power consumption to flow loss of fluid is adopted to validate this method. To obtain the optimal flow structure in a tube, the tube flow is divided into two parts: core flow and boundary flow. For reducing the irreversibility loss in the core flow, we take fluid exergy destruction as optimization objective with prescribed fluid power consumption. For reducing the flow resistance in the boundary flow, we take fluid power consumption as optimization objective with prescribed fluid exergy destruction. The optimization equations for the convective heat transfer in laminar flow are derived, which are solved numerically. The longitudinal swirling flows in the tube are found at different parameters. In the optimized flow, heat transfer is enhanced greatly while accompanied with a little increase of flow resistance. Comprehensive performance, the ratio of increases in heat transfer and flow resistance, reaches at 3.65 after optimization.