中文摘要：

在压力23～28 MPa、质量流速700～1 300 kg/（m2·s）、热流密度200～800 kW/m2的参数范围内,对超临界水冷堆堆芯棒径D=8 mm、栅距比P/D=1.2的类四边形子通道内超临界水的传热特性及管壁温度分布进行了试验研究,分析了压力、热流密度和质量流速对管壁温度及传热特性的影响,并与环形通道内超临界水的传热特性进行了对比。试验结果表明：在超临界压力区,类四边形子通道管壁温度随着焓值的增大而逐渐上升,换热系数在拟临界点附近达到峰值,低焓值区的换热系数比高焓值区大;随压力增大,壁面温度升高,换热系数峰值减小;热负荷的增大和质量流速的减小均会使壁面温度升高,换热系数减小,削弱传热强化。与环形通道对比发现,在低焓值区,类四边形通道与环形通道内壁温度和换热系数相差不大;超临界水在类四边形子通道内比在环形通道内更容易渡过拟临界区,拟临界区对类四边子形通道的影响比对环形通道的影响小。

英文摘要：

Within the range of pressure from 23 to 28 MPa, mass velocity from 700 to 1 300 kg/（m2·s）, and inner wall heat flux from 200 to 800 kW/m2, the inner wall temperature distribution and heat transfer characteristics of supercritical pressure water flowing in sub-channel with square distribution of supercritical water cooled reactor（SCWR） were investigated experimentally. The sub-channel was formed according to the fuel rods of the diameter 8 mm, and the pitch-to-diameter ratio was 1.2. The effect of pressure, mass velocity and inner wall heat flux on inner wall temperature distribution and heat transfer characteristics were analyzed. The characteristics of heat transfer in sub-channel with square distribution were also compared with annular channel. The experimental investigation results show that the inner wall temperature increases gently as the bulk enthalpy of water increases when the bulk temperature is less than the pseudo-critical point. The heat transfer coefficient reaches a peak at the vicinity of the pseudo-critical temperature point. Moreover, heat transfer coefficient in the low enthalpy region is larger than the high enthalpy region. The wall temperature increases with the pressure increasing at the same mass velocity and inner heat flux, but the heat transfer coefficient peak decreases with the pressure increasing. The increasing of heat flux and the decreasing of mass velocity can improve the wall temperature and decline the heat transfercoefficient, which also reduce the peak of heat transfer coefficient, and weaken the enhancement of heat transfer. Compared with annular channel, the wall temperature and heat transfer coefficient of sub-channel with square distribution are in accord with that of annular channel in low enthalpy region. Supercritical water in sub-channel with square distribution geting through the pseudo-critical region is easier than that in annular channel. The pseudo-critical region has less effect on supercritical water in sub-channel with square distribution than annular