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The interaction of surface radiation and conduction with natural convection heat transfer from a vertical flat plate assembly, with an embedded heater, has been investigated, both experimentally (using differential interferometer) and numerically (using FLUENT), in the present work. In the absence of radiation, the asymptotic limits that can be attained by the heated plate are isothermal and isoflux conditions. High values of plate thermal conductivity tend to make the surface isothermal, where as, lower values of thermal conductivity tend to make it isoflux. Irrespective of the thermal conductivity of the plate, an increase in the emissivity reduces the average temperature of the plate and brings the plate toward isothermal condition. A new methodology has also been proposed to determine the thermophysical properties, emissivity and thermal conductivity, the consistency of which is tested by carrying out experiments for various heat inputs and comparing the estimated values with those available in literature.

Thermal contact conductance is used to indicate the resistance offered by a contact interface to the flow of heat. When an interface material is applied as nano-layered coatings on super-finished contacting surfaces, the possibility of size effects necessitates the use of a discrete computation method for its analysis. Hence, a methodology is proposed which utilizes Molecular Dynamics (MD) simulations to obtain the size affected thermal conductivity of the interfacial layer, which in turn characterizes the thermal contact conductance behavior. Molecular Dynamics codes have been developed, making use of Sutton-Chen many-body potential, suitable for metallic materials. The model includes the asperities at the contact interface, assuming the asperities to be of a simplified geometry. The paper also presents the validation of the codes developed, and parametric studies on the effect of temperature, number of asperities and the material used for thermal interface coating on the size-affected interfacial conductivity.