| Summary: | A need was identified to test multi–layer vacuum super insulation (MLVSI) used in
cryogenic applications for hydrogen storage. The study focuses on the application of
commercially available MLVSI to a locally patented liquid hydrogen cryogenic storage
system. This led to an investigation of different types of multi–layer vacuum insulation
configurations, as well as further research on tank inlet coupling configurations. It
includes the manufacturing of a liquid nitrogen testing cryostat to be able to test and
evaluate the system performance.
The first set of tests was based on the development of an inlet coupling configuration to
limit heat transfer through the inner tank inlet, of a double cryogenic tank system in
order to reduce gas boil–off. The couplings were manufactured in the form of a bellow to
handle cryogenic vacuum levels, while ensuring low heat transfer rates between inner
and outer tanks. It was found that various coupling designs can be considered to limit
gas boil–off.
The second set of tests was conducted on a specific MLVSI configuration to determine
its effectiveness to insulate the spherical header surface of a typical hydrogen storage
vessel. The installation procedure, to limit heat transfer and boil–off due to edge effects
in this configuration was investigated. It was found that insulation–overlap–edge effects
will always have an impact on insulation performance when a spherical header of a
storage vessel is insulated, due to its specific geometry. A time efficient way to install
MLVSI on such a spherical header is presented and evaluated.
Further investigations were carried out by combining findings into one single system to
determine the performance of an optimised insulated cryogenic system. It was found
that copper plate discs installed between the vanes of a bellowed inlet/outlet nozzle is
the most promising to limit heat transfer to the cryogenic fluid. === Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.
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