‫٭‬ Analysis of Combined Conduction-Radiation Heat Transfer in Multilayer Insulations

M Maerefat, A Esmaili
2014 Amirkabir Journal of Science & Research (Mechanical Engineering) (AJSR-ME   unpublished
Modeling the combined conduction-radiation heat transfer in multilayer insulation has been done. Governing equations of the problem are integro-differential and there is no exact solution for them. So numerical procedure with the approximate solutions have been used. Main governing equations were energy equation and two-flux equations using the finite volume and finite differences have been discretized, respectively. Numerical solution is validated with Ozisik's solution and the experimental
more » ... the experimental results were published. Total heat flux and effective thermal conductivity obtained via steady state results. Dimensionless temperature distribution and dimensionless radiative and conductive heat fluxes along the sample thickness were obtained. Near the hot boundary, dominating mode is radiation, so it is suggested that the reflective screens are located near hot boundary. For the lower temperature differences, the dominating mode is conduction, so the number of reflective screens does not influence effective thermal conductivity so much. In all steps of validation, the numerical results have good agreements with the published data in the references. Finally, it is suggested that just the foils near the hot boundary, are coated with gold for the sake of cost cutting. In addition, it is understood that layer density has an optimum value and this value does not change if the boundary conditions and the material remain unchanged.