水平管束外凝结换热数值计算

The Numerical Calculation of Condensation of Heat Transfer Outsaide Horizontal Tube Bundle

应用FLUENT商业软件,模拟水蒸气在水平管束外遇冷凝结的流动情况,数值模型基于多相流混合物模型,模型中加入自定义函数以实现蒸汽向水的转换,利用有限体积法及SIMPLE算法和标准的k-ε双方程求解控制方程组,得出换热器的表面传热系数,内部混合相压力、速度、温度的变化分布。模拟了管外径d=20 mm、排列方式分别为顺排和错排,在不同的横向间距S1以及不同的纵向间距S2下的换热情况。结果表明不论是顺排还是错排均在S1/d=1.4,S2/d=1.2下结果最优,在最优情况下错排构成的换热器表面传热系数比顺排高1.7倍,为设计高效冷凝换热器提供参考。

This paper uses the software FLUENT to simulate the flow condition of the water vapor when it condenses as it comes to the outside horizontal tube bundle. The numerical model used in this paper is based on multiphase mixture model. The user-defined function is added to the model to realize the conversion process of steam to water. It uses finite volume method, SIMPLE algorithm and k-ε double equation to solve the governing equations. And finally, the surface heat transfer coefficient of the heat exchanger well as the distribution of changes of the inside mixed phase＇s pressure, velocity, and temperature, are worked out. This paper simulates the heat exchange process under the following conditions： pipes external diameter 20 mm （d = 20 mm） , exchangers arranged respectively in line and staggered, space varied by the horizontal spaces （S1 ） , and s longitudinal spaces （S2）. The resuits show that the optimal result is obtained under the condition of S1/d = 1.4 and S2/d = 1.2 whether they are arranged in staggered or in line. Under the optimal situation, the surface heat transfer coefficient of heat exchanger arranged in staggered is 1.7 times higher than that in line. Therefore, this study provides reference for designing efficient condensing heat exchanger.