Experimental investigation on the temperature and pressure characteristics of supercritical helium for liquid hydrogen pressurisation

Abstract

Liquid hydrogen is a good energy storage medium for heavy-lift launch vehicles owing to its high energy density. A suitable pressurisation system is required when liquid hydrogen is injected into the combustion chamber from the storage tank. Helium has the advantages of stable properties and low density. Therefore, when it is used for liquid hydrogen pressurisation in heavy-lift launch vehicles, the weight can be greatly reduced. An experimental setup for supercritical helium natural convection heat transfer for liquid hydrogen pressurisation was established in this work, and the temperature and pressure characteristics during the processes of filling with liquid nitrogen, filling with helium, heating, and repeated heating were analysed based on the setup. The results showed that the cooling rate during the cooling process in the experimental cavity filled with helium was mainly dependent on the distance between the measuring point and the inner wall of the cavity, but not on the height. The heating rate in the upper part of the cavity was the fastest during the process of filling with helium as the supercritical helium with higher temperatures accumulated in this region. The pressure in the cavity substantially affected the dynamic characteristics of the temperature and pressure of the supercritical helium during the heating process. The pressurisation efficiency was increased by approximately 4.6 times when the initial pressure was increased by 7 times. The results are helpful for improving the liquid hydrogen energy storage efficiency, as well as realising a safe and efficient pressurisation of liquid hydrogen.