Thermal performance analyses of fuel porosity and pellet-clad interface are important in thermal analysis of nuclear fuel rod. Many analytic researches have been performed to these problems, but they have difficulties in simplifing the problems. This difficulties can be solved by using of numerical methods. The solution method employs Body fitted coordinate systems which transforms the region under study onto a fixed rectangular domain where computations are done easily. Consequently, this method can increase the density of coordinates within the region where temperature profile changes greatly.
1. Effective thermal conductivity of porous material decreases as increasing in porosity and A/B of elliptic pore and as decreasing in thermal conductivity ratio of pore to medium. Effective thermal conductivity is expressed as a function of these variables in eq. (8).
2. Assuming that pore shape is randomly oriented elliptics, effective thermal conductivity decreases more than that of circular pore.
3. Heat transfer coefficient of contact surface increases as increasing in contact pressure and as decreasing in roughness-wavelength ratio.
