Simultaneous Estimation of Thermal Properties by Non-Linear Least Squares Method

A new method, which utilizes the non-linear least squares method, is proposed to estimate simultaneously the thermal conductivity, the heat capacity and their temperature coefficients. This measurement principle is further expanded so as to measure the heat of chemical reaction. In the measurement, a hollow cylinder is heated from both the central axis and the outer surface. It is found that the optimum location of the minimum temperature in the specimen should be in a middle part between the center and the outer surface in order to reduce measurement error. The effective thermal conductivity and the heat capacity of a packed bed of glass and aluminum oxide are measured from 300 K to 700 K at a heating rate of 2-3 K/min. The endothermic quantity of transition (KNO3) and dehydration (CaC2O4·H2O) are also measured at a heating rate of 2 K/min. The results agree well with those determined by other measuring techniques. By using this method, therefore, the thermal conductivity, heat capacity and heat of reaction which are necessary to solve heat conduction problems can be determined simultaneously.