Film condensation heat transfer of high-pressure and low-mass-flux steam in inclined tube

Abstract

High pressure conditions with a compact condensation system are used for high efficiency. In this regard, we present herein an experimental study on the film condensation heat transfer under low-mass-flux high-pressure steam in an inclined tube. The effect of each parameter on the film condensation was analyzed based on the average heat transfer coefficients determined by the logarithmic mean temperature difference method for different steam mass fluxes (27, 54, and 82 kg/m2 s), pressures (0.5 and 2.0 MPa), and inclination angles (−37.5°, −15°, 0°, +7.5°, and +30°). Condensation heat transfer coefficient generally tends to decrease as the steam quality decreases, however, we found regions where Nu in one direction is higher than that in other directions. We expect this is caused by different flow pattern transition points for flow directions and discuss local heat transfer changes for the flow patterns based on the effect of vapor-liquid interfacial wave and film curvature. The obtained reference data for high-pressure steam in inclined condensation tubes and is expected to contribute toward the design of advanced energy systems involving high-pressure condensation components.