Transient thermal modeling of multilayer-insulated liquid-hydrogen tanks: Steady-state error compensation and chilldown boil-off
Year: 2026
Type: article
Abstract: A one-dimensional radial finite-volume model is developed to simulate the transient thermal response of a liquid-hydrogen cryogenic tank during filling and storage. The wall combines an aluminum liner, polyurethane foam, a multilayer insulation (MLI) blanket, an evacuated annular gap and an outer shell; a single geometric exponent handles flat, cylindrical and spherical geometries. All properties are temperature dependent, and the MLI sub-model resolves the radiative conductance, the spacer conduction and the thermal inertia of the shields and spacers. The central result concerns error compensation. When a flat-wall model is combined with a constant emissivity of the order of 0.03, as commonly done in the literature (the spacer conductivity being kept temperature dependent), the flat-wall underestimate and the constant-emissivity overestimate are of opposite sign and nearly cancel on the steady-state heat flux (＋5% net), so that a satisfactory steady-state prediction can be obtained for the wrong physical reasons. This near-cancellation is coincidental rather than structural: a fully simplified model that in addition freezes the emissivity at 0.05 and the spacer conductivity at its ambient value does not benefit from it (＋45%). Nor is the cancellation reproduced in the transient regime, where the same assumptions produce individually larger, differently distributed errors in the time constant. Comparison with the NASA MHTB test bed reproduces the measured heat flux with a physically plausible spacer fraction, though this single benchmark cannot demonstrate universal predictive capability. Applied to the filling phase through a coupled 1D-thermal/0D-thermodynamic model, the transient heat flux far exceeds its steady-state value during the first time constants. The chilldown energy absorbed by the insulating wall ( ≈ 1 3 . 9 M J , i.e. about 31 kg of boil-off, roughly 26% of the stored load of the reference tank) is therefore underestimated by more than an order of magnitude (a factor of about 40) by a quasi-steady, constant-flux assumption, with direct consequences for boil-off management and for the pressure-safety margins of liquid-hydrogen tanks in the energy sector.
Source: Applied Thermal Engineering
Author: Jean-Gabriel Bauzin
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,660
OpenAlex ID: W7222806047