Flow and heat transfer on cryogenic flow boiling during tube quenching under upward and downward flow

The gravity effects on quenching of tube by cryogenic fluids for the development of cryogenic fluid management on orbit are studied. In this paper, the effects of the tube diameter, the flow directions, and the mass velocity on the tube quenching using liquid nitrogen are investigated systematically in the terrestrial conditions. The experiments are performed by the mass velocity between 100-600 kg/m² s in downward and upward flow directions by using three difference inner diameters of the transparent heated tube (7, 10, 13.6 mm) for measuring fluid behavior observations and heat transfer measurements simultaneously. The results indicate that the difference between the minimum heat fluxes under downward and upward flow conditions increased as the mass velocity increased. These characteristics of heat transfer were caused by filamentary flow pattern that was found in only downward flow and high mass velocity conditions.