New methods of testing heat leak in cryogenic vessels

A new method for evaluating the heat leak of cryogenic vessels without exhaust gas

“…During self-pressurization, because the environment temperature is higher than the temperature of the vapor and liquid in the cryogenic vessel, the heat transfers from the environment to the vapor and liquid [ [8] , [9] , [10] , [11] ], which is expressed as where is the heat leak transferred from the environment to the vapor and liquid through the wall, is the equivalent thermal conductivity, T is the temperature, and is the heat-conduction area.…”

“…Meanwhile, the liquid absorbs heat leaked through the inner wall as described by Eq (3) , causing the temperature and internal energy of the liquid to increase, and a part of the liquid is converted into vapor. These increases are expressed as [ 9 , 15 ] where is the density of the liquid, is the volume of the liquid, is the specific internal energy of the liquid, is the pressure of the liquid, is the latent heat of vaporization, and is the mass rate of the vaporized gas (BOG). is the difference between the internal energy of the vapor and liquid of the BOG as it evaporates into vapor.…”

“…Furthermore, if the working medium is a liquefied natural gas or hydrogen, the discharged gas is hazardous. To shorten the test time and save the working medium, new methods have been proposed for directly testing the heat leak of cryogenic vessels, although the measurement accuracy is not very high [ [9] , [10] , [11] ]. A semi-experimental and semi-analytical method was proposed for testing the BOG rate of a cryogenic vessel at low liquid level ratio to predict the BOG rate and heat leak at high liquid level ratio based on the one-dimensional heat transfer model; however, the errors in the experimental and predicated data were over 20 % for instantaneous BOG [ 11 ].…”