Analysis of the effect of humidity diffusion occurred at polyurethane used for insulating material on thermal conductivity coefficient

Polyurethane foam used as insulation material has a porous structure. Temperature difference occurring in using condition creates saturation pressure difference over the polyurethane foam. This difference causes moisture penetrating into the materiel from surface by diffusion. The moisture penetrating into the porous foam makes structure thermal insulation worsen by affecting the thermal conductivity of the material have been demonstrated in studies conducted in various industries. In this study, model of polyurethane foam used as the core material of panel in refrigerated vehicles has developed to calculate the thermal conductivity coefficient by measuring the amount of moisture according to usage profile of the refrigerated vehicle and model correlation was confirmed by the thermal conductivity coefficient measurement. As a result of this study, a mathematical model that allows calculation of the effective thermal conductivity coefficient was demonstrated regarding to the amount of moisture penetrating into the polyurethane foam by diffusion. In conclusion, thermal conductivity coefficient was calculated according to the amount of moisture penetrating into the polyurethane foam by diffusion.