低 Re 数下的强化传热及其方法评价

Intensified Heat Transfer under Low Re Number and the Method of Evaluation of Exergy

对光管、内插扭带管、螺旋槽管三种不同换热元件进行了实验，整理出了管内换热与阻力经验公式，导出了管内流动火用损失方程。根据经验公式与火用损失方程，计算了三种元件的最佳流动工况Ｒｅｏｐｔ及最小火用损失率Ｎｅｍｉｎ。通过比较与分析，得出了高粘性流体管内最佳工况为层流，及低Ｒｅ数下，内插扭带管的换热与阻力综合性能较优等结论。

Experiments were conducted with respect to three kinds of heat exchange elements,i.e.bare tubes,inserted twisted band tubes and spiral groove tubes.Worked out is an empirical formula for in tube heat exchange and resistance and deducted also is an exergy loss equation for in tube flow.An optimum flow condition Re opt and minimum exergy loss rate Ne min were calculated for the three types of elements.By way of comparison and analysis some conclusions were obtained,among others,that the optimum in tube operating condition for a high viscosity flow is a laminar flow,and under low Re number the comprehensive performance of heat exchange and resistance for inserted twisted band tubes is relatively superior.