水平圆管内超临界甲烷对流换热数值模拟

摘要

In order to study the supercritical liquefied natural gas ( LNG ) heat transfer characteristics in tubes, methane is used herein to replace LNG to investigate the numerical simulation of convective heat transfer of super-critical methane in a horizontal tube. The heat transfer characteristics of methane under supercritical pressure is found out by changing the inlet velocity, wall temperature of the tube and pressure. The results show that the sur-face heat transfer coefficient has a peak value at the critical point, which demonstrates that it is beneficial to heat transfer under supercritical condition. The influence of inlet velocity on the heat transfer coefficient is significant, the surface heat transfer coefficient increases with the increase of inlet velocity. The wall temperature has a little in-fluence on the heat transfer coefficient;with the increase of wall temperature, the heat transfer coefficient decreases slightly. The influence of pressure on the heat transfer coefficient is related to critical temperature. When the fluid temperature is below the critical temperature, the surface heat transfer coefficient decreases with the increase of pressure, but when the temperature is higher than the critical temperature, the heat transfer coefficient increases with the increase of pressure.%为了研究超临界液化天然气管内换热特性,使用甲烷替代液化天然气,对超临界甲烷在水平管内的对流换热情况进行了数值研究. 通过改变甲烷的进口速度、换热管壁面温度和压力,得到超临界甲烷在管内的换热特性. 结果表明,在临界点处表面传热系数出现峰值,表明临界点处有利于换热. 速度的改变对表面传热系数影响很大,随着进口速度的增大,表面传热系数变大;壁温对传热系数影响较小,随着壁温升高表面传热系数略有下降;压力对传热系数影响与临界温度有关,当流体温度低于临界温度时,随着压力的升高表面传热系数变小,但当温度高于临界温度时,随着压力的升高表面传热系数变大.