Method of testing thermal conductivity at steady state for insulating materials; polyurethane and hollow bricks results of the measurements

摘要

The study of thermal properties of building materials is an important axis of research in economy of energy in building. In our labortory, we have been interested in the thermal characteristics of insulating materials, especially the thermal conductivity. Now there are many methods of measurement of thermal conductivity, especially the method of guarded hot plate and the method of radial heat flux. These methods give thermal conductivity with a good accuracy but they are slow and difficult in the experimentation. In the Thermal and Energy Laboratory, we use a new measurement method of the thermal conductivity: "the box method", the measurement time could be less than four hours per sample with a good accuracy and the cost of the device is not expansive. Measurements of polyurethane samples, used in thermal insulation of building, have shown the opened and closed porosity and the real density influence on the thermal conductivity. We have also investigated the thermal conductivity of hollow bricks, used in local construction (Northern Morocco). We are interested in the influence of water volume rate on the thermal conductivity.