An experimental and theoretical study of the nonlinear heat conduction in dry porous media

Abstract

Heat transfer in porous media is important in various engineering fields, including contaminated soil incineration. Most heat transfer models are theoretical in nature. Consequently, this study was undertaken to perform both theoretical and experimental studies of heat transfer in two different sand matrices. A mathematical model based on Fourier's law of heat conduction for a one‐dimensional system with the variable thermal conductivity was developed. The experimental part included heating sand samples placed in a small reactor within an infrared furnace. The transient temperature profiles of the sand layers were monitored by thermocouples. The bulk thermal conductivity was estimated to be linearly proportional to the temperature. The temperature profiles predicted by the model of heat conduction with a variable bulk thermal conductivity was compared by the observed temperatures in Quartz and Sea sands matrices up to 1300 K. Copyright © 1999 John Wiley & Sons, Ltd.

An experimental study of soil thermal conductivity using a guarded hot plate apparatus

“…Firstly, the inadequacy can be explained partially by the complexity of the model formulation itself, since the thermal conductivity of soil depends on numerous complex parameters (such as mineral composition, moisture, texture, porosity and particle size distribution, etc) which are difficult to incorporate into a single model [4][5][6]. Secondly, in order to properly calibrate and verify an analytical model, reliable experimental data is required; meanwhile there is a lack of comprehensive and accurate experimental research, especially in cases of low moisture contents and temperatures beyond 60°C [4,7]. It is important to note that only a few limited high temperature studies (up to and above 60°C) have been conducted.…”

“…Relative to the single probe approach, the benefit of dual probe technique is that it is able to measure both thermal diffusivity and volumetric heat capacity. From this, all the main soil thermal properties can be determined, including thermal conductivity [4,7]. In general, most of the transient techniques are quick and portable, and require small soil specimens, and as such are commonly used in the field and industry.…”

“…To the author's knowledge, even the most recent and advanced analytical and numerical studies involving the theoretical modeling of soil thermal conductivity (amongst them Shiozawa and Campbell [2], Gori and Corasaniti [3], Pourhashemi et a/. [4], Tarnawski and Leong [12], Tarnawski and Gori [13], Abu-Hamdeh [14], Naidu and Singh [15]) have been verified on the basis of limited experimental data, especially at temperatures beyond 60°C.…”

A conceptual framework for modelling the thermal conductivity of dry green roof substrates

“…Suggestions were made for considering thermal decomposition of organic matter (OM), which may influence temperature evolution and thus improve the prediction. Two other studies on predicting temperature profiles during extreme surface heating were conducted on dry sands (Pourhashemi et al 1999;Enninful 2006). Both studies were in good agreement with the laboratory measurements, provided that temperature-dependent thermal conductivity was used.…”