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In this paper thermal properties of conductive thin films on aluminium substrate are investigated using a phototyhermal method. In the first case the film thermal conductivity and heat capacity, the thermal contact resistance between thin and substrate and the convective heat transfer coefficient are simultaneously estimated. Secondly, the case of anisotropic thin fihns is studied. In that case, axial and radial thermal conductivities and the heat capacity of the thin fihn are simultaneously determined with the convective heat transfer coefficient. For the parameter estimation an inverse technique, based on Levenberg-Marquardt algorithm, is performed. [ABSTRACT FROM AUTHOR]

Knowledge of thermophysical properties is a major challenge to the numerical modeling of heat transfer in liquids. In the present paper, a novel experimental technique is implemented to measure these characteristics. This technique consists on exciting the front face of a three layered sample with a crenel heat flux and measuring the temperature response on the rear face. The three layered sample is formed by a Teflon cell filled with liquid and covered by two copper layers on its front and rear faces. A 1D dimensional model is developed to simulate conductive heat transfer in the sample. The thermophysical parameters are estimated by minimizing the OLS norm referring to the difference between calculated temperatures and the measured signal. This minimization is performed by the Gauss-Newton method. The effective thermal conductivity and the biot number are estimated for two different liquids. The parameter uncertainty is analyzed and a good agreement with literature values is obtained. [ABSTRACT FROM AUTHOR]

Modeling plays an important role in the development of Proton Exchange Membrane Fuel Cell (PEMFC), because it allows a better comprehension of the parameters affecting the fuel performances. PEMFC performances are strongly related to the mechanisms of mass transfer in the stack. The objective of this study is to develop a comprehensive model describing the transport phenomena in the cell and these influences on the fuel performances. First, we present the electrochemical model that takes into account the thermodynamic open circuit voltage and different voltage losses. Second, we present gas diffusion in porous electrodes, water diffusion and electro-osmotic transport through the polymeric membrane. The solutions of the mass transfer equations are used to calculate the fuel cells performances at different operating conditions. [ABSTRACT FROM AUTHOR]