Study of thermal conductivity coefficient of basalt fiber insulation at various temperature conditions

Abstract

Industrial thermal insulation fibrous materials (mineral wool and fiberglass products) are mainly used for thermal protection of the systems transporting high-temperature heat carriers. The data known in the scientific literature about the effect of insulation density and operating temperature conditions on the thermophysical properties of materials made of basalt fiber differ significantly. Taking these data into account let us improve the accuracy of thermal calculations and the validity of design solutions for thermal protection of industrial networks up to 60 %. The aim of the study is to obtain data on the change of the heat-shielding properties of insulating materials made of basalt fiber of various densities, depending on the temperature conditions of operation. An experimental study of the thermophysical properties of several samples of basalt fiber insulation has been carried out on a laboratory bench. The density of a constant heat flux passing through the sample has been determined by the additional wall method. The experimental unit consists of a cylindrical metal tube with a built-in electric heater, on the top of which a heat-insulating basalt fiber of various densities is placed. The temperature on the pipe surface is changed in the range from 50 to 350 оC. The dependence of the thermal conductivity coefficient of thermal insulation basalt fiber samples on its density and operating temperature of the material is obtained. The research results show that thermal conductivity coefficient of basalt fiber insulation increases with temperature increase of the pipeline surface. The lower the value of the material density is, the higher the increment of the thermal conductivity coefficient is. The obtained results enrich the data about the dependence of the thermal conductivity of fibrous heat-insulating materials on density and temperature (for cases of operation at high temperatures). Considering the density of the examined materials made of basalt fiber when determining the thermal conductivity makes it possible to increase the accuracy of calculations up to 20 % and temperature modes of operation up to 60 %. The results obtained can be applied to find the thickness of the thermal insulation of pipelines and heat losses in the networks.