Flashing Phenomena of Liquid Nitrogen in a Pressure Vessel Under Rapid Depressurizations

In recent years in Japan, the demand of cryogenic fluids like a LH2, LNG is increasing because of the advance of fuel cell device technology, hydrogen of engine, and stream of consciousness for environmental agreement. The purpose of this study is to clarify some fundamental features of the flashing of cryogenic fluids. Experiments on flashing of liquid nitrogen were conducted to clarify the effect of surface roughness of a vessel. Two types of pressure vessel were used. One is a vessel made of stainless steel, the other is a vessel made of glass. In the case of glass vessel, many types of boiling have been observed. The degree of superheat at the start of boiling was found to depend strongly on the rate of depressurization.