This study shows the results of measurement and evaluation of the thermal conductivity and density of the nanosuspension type latent heat storage material in which the latent heat storage material is dispersed in nano size. The latent heat storage material dispersed in the test nano suspension is tetracosane with a melting point of 50.6 ° C, and is dispersed in distilled water using a nonionic surfactant. The latent heat storage material dispersed by using an ultrasonic homogenizer has an average diameter of 265 nanometers. The data of density and thermal conductivity of nanosuspensions as a flowable latent heat storage materials are provided useful basic data for the design of latent heat storage systems. In this study, a density hygrometer is used to measure the density of the nanosuspension, an experimental device of transient hot wire method is used to measure the thermal conductivity. The measurement range are the mass composition ratio of dispersoid 10.0 to 40.0mass% and the temperature of 10 to 84°C. It is shown that the density of the test nanosuspension can be estimated by the additivity law, and that the Maxwell-Eucken model is effective for the estimation of the thermal conductivity.

The thermal conduction of homogeneous and dense semitransparent materials like glasses consists of conductive and radiative heat transfer. The apparent thermal conductivity in steady state of semitransparent material where conductive and radiative heat transfer coexist is necessary. After deriving a temperature equation at infinity in Laplace space when steady heating one end of a 3-layer material with semitransparent material sandwiched by opaque layer, the steady-state temperature distribution equation was derived and the optical thickness and temperature dependence of the temperature distribution was investigated. Apparent steady-state thermal conductivity for entire optical thickness was derived from the temperature distribution of semitransparent material. The approximate thermal conductivity equations for large and small optical thickness were derived. The apparent thermal conductivity approximation for large optical thickness showed the same trend as the apparent thermal conductivity by Rosseland.