Hydrogen is widely considered as the fuel of the future. However, there are still challenges and safety limitations to improving the storage efficiency of liquefied hydrogen fuel when it comes to its large-scale, commercial transport and storage. Presently, hydrogen fuel is transported as high-pressure gas in specialized tanks. But this technique is both inefficient and poses serious safety concerns. Liquified hydrogen fuel can only be transported in cryogenic tanks, which maintain temperatures below minus 253 degree Celsius, the boiling point of hydrogen. Despite thermal insulation, the liquefied fuel in a cryotank experiences a degree of vaporization. The flow rate of vaporization is measured as Boil-Off Gas. Too high BOG can result in excess internal pressure inside the tank, leading to cracks and fissures. This makes understanding and controlling BOG a key factor in cryotank design. To address this challenge, researchers are increasingly looking at the use of liquified hydrogen fuel.To this end, a research team, led by Professor Jong-Chun Park of Pusan National University in South Korea, has investigated how BOG varies with another critical design parameter called tank filling ratio, the ratio of the mass of liquefied fuel in the tank to the capacity of the tank at 15 degree Celsius. In study, researchers performed experiments, as well as simulations, to analyze the thermodynamic characteristics of the tankFrom their experiments, the researchers found that BOG increases quadratically with FR. They also found that while the temperature within the liquid phase remained constant, the temperature of the vapor phase decreased non-linearly with FR. The researchers then performed multiphase-thermal flow simulations of the tank using computational fluid dynamics. This allowed them to easily visualize the heat transfers, thermal flows, and vaporization within the vacuum-insulated tank. "We adopted the Rohosenow's phase change model for the simulations, which allowed us to reproduce the vaporization process within the tank. From our simulations, we were finally able to reveal the mechanism of BOG as a result of vaporization," explains Prof. Park. The researchers validated their simulations using the data from the experiments conducted through collaboration with Daewoo Shipbuilding & Marine Engineering Co
Hydrogen is widely considered as the fuel of the future. However, there are still challenges and safety limitations to improving the storage efficiency of liquefied hydrogen fuel when it comes to its large-scale, commercial transport and storage. Presently, hydrogen fuel is transported as high-pressure gas in specialized tanks. But this technique is both inefficient and poses serious safety concerns. Liquified hydrogen fuel can only be transported in cryogenic tanks, which maintain temperatures below minus 253 degree Celsius, the boiling point of hydrogen. Despite thermal insulation, the liquefied fuel in a cryotank experiences a degree of vaporization. The flow rate of vaporization is measured as Boil-Off Gas. Too high BOG can result in excess internal pressure inside the tank, leading to cracks and fissures. This makes understanding and controlling BOG a key factor in cryotank design. To address this challenge, researchers are increasingly looking at the use of liquified hydrogen fuel.To this end, a research team, led by Professor Jong-Chun Park of Pusan National University in South Korea, has investigated how BOG varies with another critical design parameter called tank filling ratio, the ratio of the mass of liquefied fuel in the tank to the capacity of the tank at 15 degree Celsius. In study, researchers performed experiments, as well as simulations, to analyze the thermodynamic characteristics of the tankFrom their experiments, the researchers found that BOG increases quadratically with FR. They also found that while the temperature within the liquid phase remained constant, the temperature of the vapor phase decreased non-linearly with FR. The researchers then performed multiphase-thermal flow simulations of the tank using computational fluid dynamics. This allowed them to easily visualize the heat transfers, thermal flows, and vaporization within the vacuum-insulated tank. "We adopted the Rohosenow's phase change model for the simulations, which allowed us to reproduce the vaporization process within the tank. From our simulations, we were finally able to reveal the mechanism of BOG as a result of vaporization," explains Prof. Park. The researchers validated their simulations using the data from the experiments conducted through collaboration with Daewoo Shipbuilding & Marine Engineering Co
