Search

Some analytical solutions of the one dimensional transient coupled heat and mass transfer linear equations in a semi-infinite medium are proposed, based on an extension of the thermal quadrupole formalism, in both axial and radial coordinate systems. A direct relationship is proposed between the local temperature and moisture content, both at wall and inner locations. For a previous characterized medium, these relationships seem to be relevant in order to deduce the moisture content from temperature measurements. Another application would be the transport parameters estimation. [ABSTRACT FROM AUTHOR]

Abstract: A new method based on the thermal quadrupoles technique for heat transfer modelling in multilayered slabs with heat sources is proposed. Classical thermal quadrupoles use hyperbolic functions and numerical problems occur according to the argument value that depends on thermophysical and geometrical properties as well as characteristics times. We propose a new formulation based on exponential function with negative argument. Using this formulation in the classical equivalent impedance network allows to compute efficiently the thermal behaviour of multilayered slabs with internal heat sources whatever the time and the thermophysical properties. This approach is applied in order to simulate heat transfer in three different multilayered materials with heat sources. These simulations show the capability of such a methodology to simulate time and space multiscale heat diffusion problems. [Copyright &y& Elsevier]

Abstract: A model of heat transfer in a SiGe heterojunction bipolar transistor (HBT) at the macro scale is established, that leads to an analytical solution. Modelling is based on the use of integral transforms as the Fourier and Laplace ones. The heat source is assumed as a heat flux applied at the base-collector junction. It is shown that the thermal behaviour of the transistor at the highest frequencies is perturbed by the deep-trench insulation of the device. Finally, it is shown the interest of this model to identify the thermal conductivity of the back-end layer which is treated as a homogeneous medium. [Copyright &y& Elsevier]

The aim of this technical brief is to test numerical inverse Laplace transform methods with application in the framework of the thermal characterization experiment. The objective is to find the most reliable technique in the case of a time resolved experiment based on a thermal disturbance in the form of a periodic function or a distribution. The reliability of methods based on the Fourier series methods is demonstrated. [ABSTRACT FROM AUTHOR]