As far as design safety and operation of heat exchangers with a horizontal flow are concerned, it is necessary to study local heat transfer coefficient, boiling pressure drop, and critical heat flux for flow in a horizontal tube. In the present experimental work, local axial distribution of heat transfer coefficient, two-phase pressure drop, and critical heat flux for the flow boiling in a horizontal straight tube with R-123 as working fluid has been studied. Experiments are performed in horizontal tubes of diameter 11.9 mm and wall thickness 0.4 mm of SS304, having a heated length of 400 mm, 600 mm, and 1000 mm for the mass flux of 180 to 1210 kg/m²s. The local wall temperature is measured using the Infra-Red thermal imaging technique. The local heat transfer coefficients are compared with six different well-known correlations. Also, the two-phase frictional pressure drop is measured and compared with eight different general correlations. In the present study, a sudden rise in wall temperature at any location of a test section is considered as the occurrence of a boiling crisis. The boiling crisis mechanism observed in the present study is of departure from nucleate boiling (DNB). It takes place in the subcooled, or low quality saturated boiling region and in-between the length of the test sections rather than at exit as in the dry-out type of CHF. The critical heat flux is compared with six different predictive correlations. The mechanism of occurrence of CHF in the present work is found to be a departure from nucleate boiling.

就水平流换热器的设计安全性和运行而言，有必要研究水平管中的局部传热系数，沸腾压降和临界热通量。在本实验工作中，研究了以R-123为工作流体的水平直管中沸腾的传热系数，两相压降和临界热通量的局部轴向分布。在直径为11.9 mm，壁厚为0.4 mm的SS304，加热长度分别为400 mm，600 mm和1000 mm的水平管中进行质量通量为180至1210 kg / m ^2的实验s。使用红外热成像技术测量局部壁温。将局部传热系数与六个不同的众所周知的相关性进行比较。而且，测量了两相摩擦压降并将其与八种不同的一般相关性进行比较。在本研究中，在任何测试区域的任何位置壁温突然升高都被认为是沸腾危机的发生。在本研究中观察到的沸腾危机机制不同于核沸腾（DNB）。它发生在过冷或低质量的饱和沸腾区域中，并且在测试段的长度之间，而不是像CHF干燥型那样在出口处发生。将临界热通量与六个不同的预测相关性进行比较。