Publication date: October 2014
Source:Building and Environment, Volume 80
Author(s): Ru Ji , Zuotai Zhang , Lili Liu , Xidong Wang
This paper developed a new random model to simulate the microstructures and the effective thermal conductivities (k e ) of the insulation materials based on the assumption of either two phases or multiphase. To support the validity of the proposed approach, comparisons with experiments were made. These experiments can be divided into two kinds: the first one is the foamed concretes (FC) with a range of bulk densities from 354 kg/m3 to 1341 kg/m3, which are manufactured by the pre-foaming type; and the second one is the lightweight concretes (LWC) with densities ranging from 526 kg/m3 to 1895 kg/m3, which are made up of Portland cement (PC) and expanded perlite (EP). For the comparison with the simulation results, the k e was measured by a guarded hot plate apparatus (GHP). The results indicated that the simulation results of k e by the present model are in good agreement with the experiment values. For each sample, k e increases with the increase of the bulk density of the sample. Moreover, the degree of k e decrease becomes small in the lower bulk densities. In addition, the present model gives a detailed description of the heat transfer behavior in the insulation material.
Source:Building and Environment, Volume 80
Author(s): Ru Ji , Zuotai Zhang , Lili Liu , Xidong Wang