扁平管交错蛇形短翅片强化传热的研究

针对火电空冷凝汽器采用的扁平管蛇形翅片长度较大,空气在翅片间流动对强化传热的效果受到边界层发展抑制的缺陷,根据锯齿翅片通过破坏边界层发展强化传热的思想,提出一种扁平管交错蛇形短翅片结构。实验结果表明,扁平管交错蛇形短翅片的传热性能优于原有结构,在不同雷诺数Re范围,努塞尔数Nu增加了1.4%～16%;同时空气侧流动阻力也明显增加,摩擦系数f增加了18%～45%。由综合评价指标PEC也可以得到,扁平管交错蛇形翅片有效地强化了空气侧的换热。

Study on Flow and Heat Trasnsfer of Staggered Short Wavy Fins on Flat Tube

The typical configuration adopted by air-cooled condenser in coal-fired power generating unit is the wavy finned flat tube.The development of boundary layer between wavy fins along long axis of flat tube can suppress the air-side heat transfer enhancement to a great extent.In the present study,wind tunnel experiments with numerical simulations were executed to prove that the serrated fins can enhance heat transfer obviously by breaking the development of boundary layer periodically.The experimental results showed that the staggered wavy short fin is better than the original continuous structure in heat transfer performance.At the different Reynolds number range,Nu increases by 1.4%～16%,while in the friction coefficient f increases by 18%～45%.The performance evaluation criteria,PEC,is greater than 1 under various Reynolds number of air flow, implying its potential of engineering application.