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首页> 外文期刊>American journal of applied sciences >Influence of Flow Direction on Vortex Flow Structure, Heat Transfer and Performance Improvement in Tube with V-Discreted Baffles
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Influence of Flow Direction on Vortex Flow Structure, Heat Transfer and Performance Improvement in Tube with V-Discreted Baffles

机译：流向对V形折流板管内涡流结构，传热和性能改善的影响

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Nowadays, the compact heat exchanger is used widely like a radiator, evaporator and condenser of air condition system, cooling device of electronic. Extensive studies have been done on the heat transfer characteristics and flow structure for the heat exchanger with longitudinal vortex generators by numerical method. Periodic laminar flow and heat transfer characteristics in a three-Dimensional (3D) isothermal circular tube wall with 45° in-line V-discrete baffles were investigated numerically. The computations are based on the Finite Volume Method (FVM) and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are shown for Reynolds numbers based on the diameter of the tube, Re = 100 to 1200. To generate main longitudinal vortices flows through the tested section, V-discrete baffles with an attack angle of 45° are mounted in tandem with in-line arrangement, pointing downstream (V-Downstream) and pointing upstream (V-Upstream) inserted in the middle of the tested circular tube. Effects of Different Blockage Ratio (b/D, BR) with a single Pitch Ratio (P/D, PR) of 1 on heat transfer and pressure loss in the circular tube are studied. It is apparent that in each of the main vortex flows, longitudinal twisted vortex flows can induce impinging flows on a wall of the inter baffle cavity leading to a drastic increase in heat transfer rate over the circular tube. In addition, the rise in the V-baffle height results in the increase in the Nusselt number and friction factor values. The flow structures, common-flow-up and common-flow-down are appeared by using a baffle with V-Downstream and V-Upstream, respectively. The computational results show that the optimum thermal enhancement factor is around 2.75 at BR = 0.10, Re = 1200 for V-Upstream discrete baffle.
机译：如今，紧凑型热交换器被广泛用作空调系统的散热器，蒸发器和冷凝器，电子冷却装置。通过数值方法，对带有纵向涡流发生器的换热器的传热特性和流动结构进行了广泛的研究。数值研究了带有45°直列V形离散挡板的三维（3D）等温圆管壁的周期性层流和传热特性。计算基于有限体积法（FVM），并且SIMPLE算法已实现。显示了基于管直径的Reynolds数的流体流动和传热特性，Re = 100至1200。为产生主要的纵向涡流流过被测部分，安装了具有45°迎角的V形离散挡板串联排列，指向下游（V下游），指向上游（V上游），插入被测圆管的中间。研究了单螺距比（P / D，PR）为1的不同堵塞比（b / D，BR）对圆管传热和压力损失的影响。显然，在每个主涡流中，纵向扭曲的涡流会在挡板间腔壁上引起撞击流，从而导致圆管上的传热速率急剧增加。另外，V挡板高度的增加导致Nusselt数和摩擦系数值的增加。通过分别使用带有V-Downstream和V-Upstream的挡板来显示流动结构，即共同向上流动和共同向下流动。计算结果表明，对于V上游离散挡板，在BR = 0.10，Re = 1200时，最佳热增强因子约为2.75。

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