Determination of the Load-dependent Thermal Conductivity of Porous Adsorbents
Standard measuring techniques for thermal conductivity cannot be readily applied to determine the load-dependent thermal conductivity of porous adsorbents, because the local ad- and desorption inside the specimen and the thickness of the specimen are not considered. Hence, in this work a new measuring procedure combining the transient hot bridge (THB) with a three dimensional finite element model set up in COMSOL Multiphysics® software is presented. First tests were successfully performed with the working pair active carbon and methanol. The computed effective thermal conductivity increases with rising methanol load due to the growing proportion of the thermal conductivity of the adsorbed phase. The technique extends the range of application of the THB method and sheds light on the physics influencing the thermal conductivity of porous media and can be used for detailed system simulations, e.g. regenerative filters or adsorption heat pumps.