Abstract

PENA RODRIGUEZ, G; PENA QUINTERO, J. Y  and  GOMEZ TOVAR, M. A. Experimental Determination of the Effective Thermal Conductivity in the Extruded Red Clay Bricks. Ciencia en Desarrollo [online]. 2014, vol.5, n.1, pp.7-13. ISSN 0121-7488.

It is reported the effective thermal conductivity (k_e) at 35 °C average temperature, for the blocks or the clay bricks No. 5, made by extrusion in the Cucuta city (Colombia) and its metropolitan area, which are hollow inside, and with different geometries (six rectangular, eight rectangular, eight circular and mixed). In addition to the thermal conductivity study, we calculated their mass, their apparent density, the porosity and the air fraction present in the samples. To find the k_e it was used the hot plate insulation technique at steady state. The porosity and the bulk density were calculated, by using the standard NTC 4321-3. Our results showed that the samples with a higher value than k_e were those with mixed geometry in their holes, and the lowest value corresponded to the bricks with six rectangular holes. The test confirmed that k_e was higher for samples with the increasing mass and density and diminishes for the samples with higher porosity or air fraction within them [1]. The k_e behavior, in the correlation to the air present fraction in the sample (σ), the solid clay thermal conductivity (ks) and the air thermal conductivity (kg), was found by fitting to the experimental data, using OriginPro 6.1 software and the expression k_e= P₁ks (1 − σ) + P₂kgσ, where P₁ and P₂ are parameters which can be attributed to the holes geometry in the sample. The data reported in this document, is very important to determine the thermal transmittance coefficient (U-value), used in the insulation and energy losses calculation, in a building heating design, that use such materials.

Keywords : Air Total Fraction; Effective Thermal Conductivity; Red Clay Bricks No. 5; Porosity; Thermal Transmittance.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )