Developing an Improved Heat Transfer Correlation for Applications in SCWR

Abstract

This thesis work seeks to complement ongoing research works on heat transfer from heated surface to supercritical water in the SCWR. The study was inspired by ongoing efforts directed at obtaining a correlation that predict supercritical-water heat transfer more accurately, especially with the identification of the SCWR concept as one of the six Generation IV nuclear reactors. The thesis focuses on the development of an improved heat transfer correlation for supercritical water flowing through a vertical heater in a natural circulation loop which is basically a bare vertical heater tube made of Inconnel-625, having an overall heating length of 1.37m and internal diameter of 4.62m. The study involves the investigation of some existing empirical heat transfer correlations for both forced and natural convections and then subsequently comparing their results to that of the Chen Yuzhou et al experimental dataset in order to notice their extent of deviations from the experimental data. Finally, one of the correlations considered for this study is used as a baseline to developing a more improved correlation. The parameters used for computing the selected heat transfer correlations and also developing an improved correlation are based on the wall and bulk temperatures obtained from the Supercritical-water heat-transfer dataset. The experiment for the dataset was performed in a natural circulation loop at the China Institute of Atomic Energy, China (CIAE) having pressure kept within the range of 24.2-25.2MPa, a heating power ranging from 0 to 18kW or heat flux from 0 to 0.91 MW/, and the maximum water temperature of up to 402 oC. A physical parametric sensitivity analysis was the technique used to develop and propose an improved Modified Churchill-Chu correlation with a reasonable agreement with the experimental data, having the least root mean square error of about 24% better than the investigated existing correlations