Numerical determination of the required insulation thickness for steel protection against accidental cryogenic exposure

Abstract

Cryogenic spill protection by insulation is widely used as one of the most effective risk-mitigation measures to protect steel structures against accidental cryogenic spills. This study proposed, for the first time, a numerical method for predicting the insulation thickness. The method is a combination of an optimization technique and the solution to the heat conduction problem. The major difficulty lies in the boundary condition at the boiling surface, which has not been clearly stated in the literature. To accurately determine the boundary condition, the effect of the insulation thickness on the transient pool boiling heat transfer of a cryogenic liquid on an insulated steel flat plate was first studied. It was determined that the boiling resistance generally decreased with increasing insulation thickness, which suggested that the liquid and boiling surfaces could be assumed to have perfect thermal contact. Subsequently, the assumption of perfect thermal contact was proven to be a valid boundary condition for sufficiently thick insulation layers. The developed method was verified and used to draw the correlations of the insulation thickness with the period of resistance and metal thickness. The findings of this study are expected to aid in the design of steel structure’s cryogenic spill protection systems.