电站空冷散热器动态传热特性研究

建立了空冷散热器空气侧、水侧和管壁的热平衡偏微分方程,采用改进欧拉法对离散后的方程进行求解。获得了迎面风速、循环水质量流量和入口水温阶跃变化时散热器的动态响应特性,以及变量变化程度对散热器动态过程的影响。结果表明:扰动变量阶跃变化时,变化程度越大,对应的动态响应曲线变化幅度也越大。迎面风速增加时,空气和循环水出口温度降低;循环水质量流量和入口水温增加时,空气和循环水出口温度均增加。迎面风速和循环水质量流量越大,动态响应时间越短;循环水入口水温变化时,动态响应时间不变。

Study on Dynamic Heat Transfer Characteristics of Air-cooled Heat Exchanger in Power Plants

This paper established partial differential equations based on the energy conservations for the air,circulating water and tube wall.Then it solved the discrete equations by improved Euler method,obtaining the dynamic characteristics of heat exchanger with step changes of air face velocity,circulating water mass flow rate and water inlet temperature,as well as the influence of variable change on the dynamic response of heat exchanger.The results show that the greater the step change of variables is,the more fluctuant the corresponding dynamic response curve is.The outlet temperature of air and circulating water decreases with the increase of air face velocity,and increases as the circulating water mass flow rate and inlet water temperature increases.The larger the air face velocity and circulating water mass flow rate is,the shorter the dynamic response time is.However,the dynamic response time remains unchanged when the inlet temperature of circulating water changes.