垂直矩形窄通道启动过程壁温变化特性研究

Study on wall temperature characteristics during the start-up process in vertical narrow rectangular channels

以去离子水为介质,对竖直矩形窄通道在启动过程中壁面温度的变化规律进行了研究。将一次启动与二次启动时壁面温度的变化特性进行了对比,并改变入口温度,研究了入口温度对启动壁面温度的影响。结果表明:一次启动时壁面温度经过三个阶段,即急剧上升阶段、缓慢升高阶段、缓慢上升至最高壁面温度后又缓慢降至稳态饱和沸腾阶段;二次启动时产生的沸腾滞后现象较一次启动时明显;提高入口温度可增加饱和沸腾段,减少壁面温度的波动,在一定程度上可避免壁面温度过冲对换热器的损坏。

The wall temperature characteristics during the start-up process in vertical narrow rectangular channels using deionized water as working fluids was studied.The comparison of wall temperature evolution between the first start-up phase and the second one was made.The influence of inlet temperature on wall temperature was investigated by changing inlet water temperature.The results showed that the wall temperature rising process could be divided into three stages including sharp rising stage,slow rising stage,slowly rising to the highest value and then falling down to the saturated boiling temperature.Compared with the first start-up phase,the boiling hysteresis phenomenon was more obvious than that in the second one.Increasing the inlet temperature could lengthen the saturated boiling stage,reduce the wall temperature fluctuation and avoid the damage on heater resulted from the wall temperature overshoot.