Simulation and analysis of the chill-down process for the design of a handling and distribution cryogenic subsystem
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Date
2025-07-09
Authors
Γκεσούλης, Αριστοτέλης
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Abstract
This thesis investigates the simulation of a cooldown procedure for vital subsystems, such as valves, couplings, pipes and a hydrogen panel, from ambient temperature to 5% of steady state temperature at cryogenic conditions in order to minimize the boil-off of liquid hydrogen that will be inserted afterwards. The proposed procedure contains a two-step cooling strategy embracing an MBSE approach, beginning with the feed of liquid nitrogen (LN2) in the procedure with the scope to reduce the temperature up to its boiling point which is well inside the cryogenic region. Finally, gaseous helium (GHe) is used in the last phase to plummet the panel’s average temperature to 5% of the steady state temperature.
The calculations of mass quantity and time duration for each substance used in the cooldown process are characterized as primary objectives of this research. The cooling strategy is designed to optimize temperature gradient, establishing smooth transitions between phases and eliminating thermal stresses. By calculating the exact quantities of LN2 and GHe at each step, this thesis provides a detailed analysis of the mass demands and the time-dependent behavior of the cooldown process while documenting the phase behavior of the substances in real time inside the application. The findings contribute to the broader understanding of cryogenic engineering by proposing an optimized cooldown procedure with the goal of minimal liquid hydrogen boil-off gas.
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Keywords
Chill-down, Helium, Nitrogen, Subsystems, MBSE approach