By applying the drop calorimeter method, we have designed a specific heat measuring apparatus which can be used in the temperature range from 100 to 1000°C. It is generally difficult to measure the Specific heat of porous thermal insulations, because they usually have low thermal conductivity and small heat capacity. The present apparatus can simply measure the specific heat of thermal insulation just by dropping a heated specimen into water. The specific heat of specimen measured by the apparatus is the mean specific heat between the initial specimen temperature before dropping and the equilibrium water temperature after dropping.We first measured the mean specific heat of standard specimen SRM 720 Synthetic Sapphire(α-Al₂O₃) using this apparatus, Whch is certified by National Institue of standards and Technology(NIST). The measured values agreed with the reference values by NIST within a deviation of about ±10%. A method for obtaining the true specific heat with practical accuracy using the measured mean specific heats is also proposed. Next, the measured results of the mean specific heats of six kinds of themal insulations(SiC refractory material, rock wool insulation, alumina silica fiber, calcium silicate, SiO₂ glass, and fluoro rubber) are shown, and empirical equations on those mean specific heats are obtained for each thermal insulation. Further, it was found that the Sharp-Ginther equation, which was originally proposed as an empirical equation for the mean specific heat of glass, could also be applied to the mean specific heat estimation of thermal insulations.

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The measuring method of three thremophysical parameters (thermal conductivity, thermal diffusivity, and specific heat capacity) of solids by a thermal probe with instantaneous point contact has been developed. The thermal probe is required to be uniformly preheated for the measurement. A compact probe holder is also required, which makes it easy for the tip of the probe to touch on a testing surface with a suitable contact-pressure. In this paper, the influence of an initial temperature distribution in the thermal probe on the temperature-response is discussed from the experimental and analytical results. A heated region of the probe is clarified. Influence of thermal contact-resistance between the tip of the probe and the testing surface is analytically examined. This method can reduce the influence to a negligible small. The probe is improved under the necessary conditions, and then the probe holder that is adaptable and easy for anyone to handle is developed.

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