The design and construction of a cryostat for thermal battery investigations.
Loading...
Date
2011
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
A test cryostat was constructed to investigate the potential of a locally made thermal battery.
A thermal battery is proposed to be a useful component in the construction of future
superconducting fault current limiter (SFCL) systems. The heat generated from a SFCL
under quench conditions can be conducted into a solid nitrogen thermal battery. This is an
alternative to using a liquid cryogen which on evaporation would form a highly nonconductive
vapour layer around the SFCL and could be potentially explosive. The relevant
heat transfer mechanisms for cryostat design were analyzed to ensure that the cryostat was
capable of solidifying nitrogen and thus be used as a thermal battery. The experimental stage
was ultimately capable of reaching a temperature of 40 K. Using a resistor to mimic the
normal state of a superconductor, the performance of the thermal battery was determined by
subjecting it to transient thermal events. The effect of solid nitrogen crystal size was
investigated by performing pulse tests on solid nitrogen formed at different rates. It was
found that slowly formed solid nitrogen performed better and stabilised the resistor’s
temperature more quickly. The phenomenon of ‘dry-out’ was also investigated for different
formation rates by subjecting the solid nitrogen to multiple heating pulses. It was found to
become very significant after the first pulse when using quickly formed solid nitrogen, but
did not manifest in slowly formed solid nitrogen.
Description
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.
Keywords
Cryostats., Superconductivity., Thermal batteries., Theses--Electronic engineering.