Assessment of insulation systems for aircraft liquid hydrogen tanks

Abstract Liquid hydrogen (LH2) has ~2.8 times more energy per pound of fuel than Jet-A, however, it requires ~4 times the volume for the same energy. As a result, LH2 aircraft developments are highly dependent on the hydrogen tankage as well as the insulation system requirements. To better understand the sensitivities that hydrogen puts onto the aircraft as a system, Georgia Tech investigators, as part of a NASA preliminary evaluation activity, have developed a single-aisle LH2 passenger jet. As a part of the activity, NASA and Georgia Tech developed the ability to integrate a tank set into the aircraft including insulation systems. Assessments are made on several insulation system options to assess the amount of venting as well as the impacts to aircraft fuel consumption. Based on the results, it is observed that even though polyurethane foam is lightweight, the associated boil-off losses drove the system level mass higher than vacuum jacketed insulations. Composite tanks are observed to decrease fuel system dry mass by several hundred kg over AL5083 tanks.