EXPERIMENTAL HEAT TRANSFER AND PRESSURE DROP OF LIQUID HYDROGEN FLOWING THROUGH A HEATED TUBE

Abstract

The heat-transfer and pressure-drop characteristics of liquid para-H flowing through a heated vertical tube were investigated over the following range of conditions: inlet pressure, 30 to 70 psi; average heat flux, 1 Btu per sq in./sec maximum; and temperature differential 50 to 750 R between the fluid and the wall. As stored in the Dewar, the hydrogen was approximately 95% para. Local pressure drop and heat-transfer coefficients for boiling H are presented. The wall temperature profile along the tube was radically different from that observed in convective heat transfer with single-phase fluids. For the larger heat fluxes, a minimum wall temperature occurred somewhere near the end of the tube, and the maximum temperature occurred near the entrance. A vapor binding or dry-wall condition was apparent in some of the H runs. An empirical correlation for predicting the two-phase heat-transfer coefficient is presented. Pressure- drop measurements showed that the frictional loss is small compared with the momentum loss. In fact, a onedimensional momentum analysis can predict the pressure drop quite accurately.