Study of behaviour of thermal insulation materials under extremely low pressure

Abstract

In most thermal insulation materials, reduced internal pressure improves thermal insulation properties. It reduces heat transport by convection as well as heat conduction in gases in the material´s pore structure. The dependence of thermal conductivity on pressure is individual to every type of insulation with open porosity. In general, a material with fine porosity is not very sensitive to pressure change within the range of very low pressure to vacuum. On the other hand, materials with a larger number of bigger pores are more sensitive to changing pressure. Any pressure change between atmosphere pressure and vacuum causes a change in thermal conductivity. The paper presents the results of an investigation into the behaviour of alternative fibrous insulations usable in the production of vacuum insulation panels at low pressure.In most thermal insulation materials, reduced internal pressure improves thermal insulation properties. It reduces heat transport by convection as well as heat conduction in gases in the material´s pore structure. The dependence of thermal conductivity on pressure is individual to every type of insulation with open porosity. In general, a material with fine porosity is not very sensitive to pressure change within the range of very low pressure to vacuum. On the other hand, materials with a larger number of bigger pores are more sensitive to changing pressure. Any pressure change between atmosphere pressure and vacuum causes a change in thermal conductivity. The paper presents the results of an investigation into the behaviour of alternative fibrous insulations usable in the production of vacuum insulation panels at low pressure.