Heat Transfer Characteristic of Supercritical Pressure Water in Nonuniform Heating Vertical Tube
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摘要: 对超临界压力水在非均匀加热的垂直上升管中的传热特性进行了试验研究。试验参数范围:p=23～30 MPa,质量流速G=600～1 200 kg/(m2.s),内壁平均热负荷q=200～600 kW/m2。试验结果表明:对于周向非均匀加热情况,热负荷及传热系数的周向分布的不均匀性随雷诺数的增加而减小;同一截面上可以同时存在传热恶化和传热强化现象,传热恶化是由局部的峰值热负荷引起的;不均匀加热的垂直上升管内的平均传热系数可以采用均匀加热条件下的公式在相应的平均热负荷下进行计算;非均匀受热管传热恶化后,加热侧中点的壁温升高比相应热负荷下的均匀加热管的低。Abstract: In this paper,experiment is carried out to get the heat transfer characteristic of supercritical pressure water in nonuniform heating vertical tube.The test parameters are as: p=23～30 MPa,G=600～ 1 200 kg/（m2.s） and q=200～600 kW/m2.The results show that for the nonuniform heating situation,the coefficient of the nonuniform heating tube can be calculated using the uniform heating tube formula with the same average heat flux;when heat transfer deterioration occurs,the wall temperature rises of nonuniform circumferential distribution of heat flux and heat transfer coefficient tend to uniformity with the increasing of Re number;at the same tube cross section the heat transfer enhancement and deterioration may occur at the same time and the heat transfer deterioration is determined by the local heat flux;the average heat transfer heating tube is lower than the uniform heating tube.
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