MODELING OF CRYOGENIC TRANSFER LINE COOL DOWN

摘要

The Cryogenic Storage and Propellant Feed System (CSPFS) of the space propulsion systems needs to provide propellant in controlled amounts during engine burns of variable duration. Thus, lines connecting the CSPFS to the engine/thruster will be subjected to cyclic cooling and heating. Here we present a model for cryogen transfer line chill-down rate. The model is based on an energy balance involving heat transfer from the outside to the pipe wall, from the wall to the flowing fluid, and energy depletion in the wall. The Morgan correlation is used for the outside heat transfer coefficient, h_a. For the inside heat transfer coefficient, h_(fb), correlations of Giarrantano et al., Hendricks et al., and Ellerbrock et al. are examined. Our model fit the literature data best when Giarrantano et al. 's superposition approach is used for h_(fb). Even better agreement is obtained when this correlation is modified to account for convective heat transfer overestimation and pipe surface effect on heat transfer.