EXPERIMENTAL CHARACTERIZATION OF THERMAL DISPERSION IN FIBROUS POROUS MEDIA

When a hot fluid is injected into a cold fibrous porous media or vice versa, energy is convected by the movement of fluid particles not only in the direction of the averaged velocity but also in the transverse direction because of the undulating flow path. This heat dispersion phenomenon can be modeled by increasing the effective transverse thermal conductivity to account for the enhancement in heat transfer. In this work, we have developed a new characterization setup to measure the heat transfer enhancement for a variety of flow rates and fiber volume fractions and introduced a modified Peclet number to describe the heat-transfer enhancement. In the experiment a cold resin is introduced in a heated mold containing fibrous media. The temperature history at the inlet, exit, and at six locations on the mold walls and three locations within the porous media is measured, and the transverse thermal conductivity in the model is varied, until all the temperature profiles recorded from the experiments match with the predicted values at all the thermocouple locations. This is repeated for various fiber volume fractions, flow rates, and two different preform architectures to develop a constitutive relationship between thermal dispersion and the modified Peclet number.