Investigation of effect of low emissivity shields on the thermal conductivity of low-density polystyrene

Abstract

In this paper, we present an experimental study on the influence of low-emissivity aluminium shields on the thermal properties of low-density expanded polystyrene. As radiation is significantly influenced by the presence of shields only on low-density materials, experimental work has been done on low-density expanded polystyrene, of which the density was about 9,5 kg m−3. Expanded polystyrene panels have been measured by the Heat Flow Meter apparatus in our laboratory. Nine sets of measurements have been done. Every panel was cut horizontally, and aluminium foils were inserted between the slices as shields. As expected, the thermal conductivity decreased considerably with the number of slices in which the material was cut and the number of aluminium shields. We found a decrease in the thermal conductivity that can even reach 25 % if we cut the panel in 8 slices with 7 aluminium foils interposed between them. We compared the experimental results with our model, which considers the presence of shields in insulating materials, and this proposed model fits the experimental results with a good accuracy. This is because almost all experimental results are situated in a zone, which represents ±2 % of error.