An Update on Heat Transfer in a Porous Insulation Medium in a Subsea Bundled Pipeline

Abstract

At the Multiphase ’99 Conference in Cannes, France, the authors presented a simple, yet general, formulation for effective conductivity of a porous insulation medium under pipeline application using fundamental continuity, momentum, and energy equations Zheng et al., 1999, “Heat Transfer in a Porous Insulation Medium in a Subsea Bundled Pipeline,” Paper No. 48 presented at Multiphase ’99, Cannes, France, ©BRH Group 1999. The effective conductivity was shown as a function of Darcy-modified Raleigh number only. The coefficients in the equation were then obtained from a set of tests for a simple pipe-in-pipe bundle with half-shell pieces of foam fitted around the inner pipe. Dramatic heat losses as experienced in some of field applications were recorded when the porous insulation foam is under high nitrogen pressure. All the heat losses were attributed to the increased heat convection within the porous insulation medium. Recognizing loose spaces between half-shells may contribute to the dramatic heat losses, the authors from R. J. Brown Deepwater conducted a new set of tests that used the same open-cell foam material, but with foamed-in-place application on the inner pipe wall. The new test data are used in this paper to derive an updated set of coefficients for the effective conductivity formulation. It is shown that such a foamed-in-place open-cell foam system maintains insulation effectiveness, even under high application pressures.