Numerical study of boiling of liquid nitrogen at solid and liquid contact planes

Abstract

The boiling of LN2 on solid and liquid surfaces is studied numerically. In the case of boiling on a liquid surface, water is chosen as the base fluid (heating fluid). Different flow instabilities and their underlying consequences during boiling of a cryogen are also discussed. Bubble diameter, departure frequency, and average heat flux are reported for a range of wall superheat of the solid surface. Reasons behind asymmetry in the bubble growth and departure time of the vapor bubbles are reported in the case of multi-mode boiling of LN2 on the solid surface. Boiling of LN2 on a liquid surface (Water) reports the rate of vapor film collapse and determines minimum thickness before rupture. The rate of thinning of vapor film thickness is compared with the inviscid theory of liquid/gas pinch off (h∼t2/3). Mutual interaction of thermo-capillarity and vapor thrust is also reported in the context of vapor film pinch-off. The difference in evaporation rate before and after vapor film collapse is computed to establish the resultant of film collapse in boiling at a liquid-liquid surface.