Local Subcooled Flow-Boiling Model Development

Several existing heat transfer models for uniformly heated channels were examined to accurately represent the boiling curve and to characterize the local heat transfer coefficient under high-heat-flux (HHF) conditions. Comparisons with HHF data showed that major correlation modifications were needed in the subcooled partial nucleate boiling (SPNB) region. Because the slope of the boiling curve in this region is important to ensure continuity of the HHF trends into the fully developed boiling region and up to the critical heat flux, accurate characterization in the SPNB region is essential Approximations for the asymptotic limits for the SPNB region have been obtained and have been used to develop an improved composite correlation. The developed correlation has been compared with 363 water data points. For the local heat transfer coefficient and wall temperature, the overall percent standard deviations with respect to the data were 19 and 3%, respectively, for the high-velocity water data.