Thermal conductivity of anisotropic, inhomogeneous high-density foam calculated from three-dimensional reconstruction of microtome images

摘要

An effective method is developed to predict the thermal conductivity of thick foam insulation on offshore oil and gas pipelines. High-resolution three-dimensional (3D) images (212 megavoxels) spanning macroscopic sample volumes (38 × 19 × 4 mm~3) are obtained and used to create a 3D geometry of the foam. A gravimetric technique is developed to measure the mass density through the foam thickness and used to verify the 3D geometry. The local anisotropic thermal conductivity through the thickness of the foam is calculated using the finite element method on the 3D geometry and the results are verified against measurements and found to be in good agreement. Results show that thermal conductivity is dependent on morphology. For the highly anisotropic part of the foam where the long axes of the bubbles are oriented parallel to the axial direction of the pipe, the radial thermal conductivity is lowered significantly compared to more isotropic foam.