结构参数对电厂翅片管散热器动态特性的影响

散热器经常处于变化的工作条件中,研究散热器的动态特性有助于改善间接空冷系统的安全和经济运行,而散热器的结构参数会影响其动态特性。根据能量守恒建立了散热器空气、管壁和循环水的热平衡偏微分方程,采用改进欧拉法对偏微分方程组进行求解。以迎面风速阶跃变化为典型工况,研究了换热面积、换热系数和工质体积对散热器动态特性的影响。结果如下:当空气侧换热面积增加时,散热器换热量增大,两个稳态之间的空气出口温度差值不变,循环水出口温度差值增加,空气侧响应时间增加,循环水侧响应时间不变。当循环水侧换热面积增加时,散热器换热量增大,两个稳态之间的空气和循环水出口温度差值不变,空气侧和循环水侧的响应时间也不变。换热系数变化时,散热器动态过程的变化规律与换热面积变化时类似。空气侧工质体积变化对散热器动态特性没有影响。循环水侧工质体积增大会使得动态响应时间变长。

Influence of Structural Parameters on the Dynamic Heat Transfer Characteristics of Air-cooled Heat Exchanger in Power Plants

The heat exchanger is always working in the dynamic conditions.Studying the dynamic characteristics of the heat exchanger is helpful to improve the safety and economic operation of the indirect dry air cooling system,and the structural parameters of heat exchanger will affect its dynamic characteristics.According to the energy conservation,the heat balance partial differential equations of air,pipe wall and circulating water are established in this paper.The effects of heat transfer area,heat transfer coefficient and working fluid volume on the dynamic characteristics of the heat exchanger are studied.The results are as follows:when the air side area increases,the heat exchange of the heat exchanger increases,the difference value of the air outlet temperature between the two steady states does not change,the difference of the circulating water outlet temperature increases,the response time of the air side increases,and the response time of the circulating water side does not change.When the heat exchange area of the circulating water side increases,the heat exchange of the heat exchanger increases,the difference value between the air and the circulating water outlet temperatureremains unchanged,and the response time of the air side and the circulating water side also remains unchanged.When the heat transfer coefficient changes,the dynamic process of the heat exchanger is similar to that of the heat exchange area.The change of working fluid volume on the air side has no effect on the dynamic characteristics of the heat exchanger.The dynamic response time will be longer with the increase of the volume of working fluid in the circulating water side.