A rapid steady-state technique was developed to measure the effective permeability and diffusion coefficients of closed-cell foam insulation. To test the new technique, N2 data were first obtained by the long-term steady-state technique, and then reproduced ten times faster by the rapid steady-state technique. By using the new technique, reference values of effective diffusion coefficients of N2, O2, and Fluorocarbon 11 in closed-cell polyurethane foams were obtained at different temperatures. Data for Fluorocarbon 11 were obtained 30 times faster than data could be obtained by long-term steady-state tests. To estimate when steady-state has been achieved, the transient diffusion equation was solved, and the solution was given in the form of a chart. The time needed to achieve steady-state mass flux in a foam sample was found to depend strongly on the ratio of the partial pressures imposed on the surface of a tested sample. By use of the solution, the value of the foam effective diffusion coefficient can be obtained before steady-state conditions are achieved within the sample.
Rapid, Steady-State Measurement of the Effective Diffusion Coefficient of Gases in Closed-Cell Foams
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Ostrogorsky, A. G., and Glicksman, L. R. (May 1, 1988). "Rapid, Steady-State Measurement of the Effective Diffusion Coefficient of Gases in Closed-Cell Foams." ASME. J. Heat Transfer. May 1988; 110(2): 500–506. https://doi.org/10.1115/1.3250514
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