Lee’s and Charlton’s Method for Investigation of Thermal Conductivity of Insulating Materials

Lee’s and Charlton’s Method for Investigation of Thermal Conductivity of Insulating Materials M. Alam1, S. Rahman2, P.K. Halder3, A. Raquib4, M. Hasan5 1,2,4,5(Department of Mechanical Engineering, Military Institute of Science & Technology, Bangladesh) 3 (Department of Industrial & Production Engineering, Jessore Science & Technology University, Bangladesh) Abstract : Thermal property is the important material property for engineering and analysis of insulating materials. In this study, thermal conductivities of insulating materials are determined and compared with the literature values. Lee’s and Charlton’s apparatus is used to measure this property of insulating materials by steady state technique. This apparatus gives more precise result for insulators that can be utilized for the further thermal related analysis. An experimental set up is prepared to determine and analyze thermal conductivities of insulating materials. The thermal conductivities are obtained by this apparatus are 0.797W/m.K, 0.3023 W/m.K and 0.057 W/m.K for borosilicate glass, styrene butadiene rubber, and polyolefin foam faced aluminum foil respectively. The experimental results are found (9-30) % deviation from the literature values. Keywords - Lee’s and Charlton’s apparatus, Steady State Technique, Thermal conductivity, Thermal Insulation. I. Introduction Thermal conductivity is the intrinsic property of a material which relates its ability to conduct heat. Heat transfer by conduction involves transfer of energy within a material without any motion of the material as a whole. Conduction takes place when a temperature gradient exists in a solid (or stationary fluid) medium. Conductive heat flow occurs in the direction of decreasing temperature because higher temperature equates to higher molecular energy or more molecular movement. Energy is transferred from the more energetic to the less energetic molecules when neighboring molecules collide. Thermal conductivity is defined as the quantity of heat transmitted through a unit thickness in a direction normal to a surface of unit area due to a unit temperature gradient under steady state conditions and when the heat transfer is dependent only on the temperature gradient. The term thermal insulation