An improved correlation for subcooled and low quality film boiling heat transfer of water at pressures from 0.1 to 8 MPa

Abstract

A semi-empirical model for inverted annular flow film boiling heat transfer was previously developed which incorporates the effects of all relevant independent parameters and agrees well with available experimental data in the pressure range from 0.1 to 2 MPa. In the present work, this model has been modified to extend its applicability to elevated pressures up to 8 MPa. New expressions for the interfacial energy transfer to the subcooled liquid jet, and for the heat transfer enhancement term due to oscillatory interfacial disturbances were derived. Steady-state film boiling heat transfer data for forced upflow of water in a vertical tube were used to determine the unknown coefficients in the new relations. The data used were obtained from steady-state experiments applying different versions of the so-called “hot-patch” technique. Finally, an explicit film boiling heat transfer correlation has been obtained which approaches Bromley's solution for zero flow and saturated conditions. This correlation has been compared with steady-state data from five different sources which cover mass fluxes ranging from 100 to 1010 kg/(m 2s) in the pressure range from 0.1 to 8 MPa. Results indicate an rms error of 15.5% and a mean deviation of 12.0% between measured and predicted heat transfer coefficients for 3972 data points.