社団法人日本機械学会 Acta Medica Okayama 0387-5016 59 567 1993 比較的浅い底面加熱を受ける上部開放矩形くぼみに球状粒子を一段充填した場合の共存対流熱伝達 286 294 EN Hideo Inaba Koichi Ozaki Shigeru Nozu Heat transfer measurements were performed during forced and natural mixed convections of a rectangular open cavity which was packed with spherical particles arranged in a one step orthorhombic array. Air flowing over the cavity was heated from the bottom surface of the cavity via the particle layer. Three kinds of spherical particles having almost the same diameter of 10 mm and different thermal conductivities were used as the spherical packing material. The cavity depth was varied from 0 mm (flat plate) to 10 mm. The particles suppressed the air motion near the heating surface and decreased the heat transfer coefficient. In the case of particles having large thermal conductivity, those particles behaved as an extended heat transfer surface and turbulence promoter so that the heat transfer coefficient was enhanced. The Nusselt number ratio as a dimensionless heat transfer coefficient was expressed in terms of Reynolds number, ratio of particle diameter to depth of the cavity and modified Prandtl number. No potential conflict of interest relevant to this article was reported.

社団法人日本機械学会 Acta Medica Okayama 0387-5016 59 567 1993 放射熱エネルギ利用融雪材の融雪機構解明に関する研究 278 285 EN Hideo Inaba Hideo Otake The melting behavior of a snow layer was investigated experimentally and numerically for the case where the snow layer was melted from the upper surface using radiative heat absorption material (black calcium carbonate powder). The experiments and calculation were carried out under various conditions of sprinkling density of radiative heat absorption material, environmental temperature, radiation heat intensity and snow density. It was clarified that an optimum density of the absorption material existed for the enhancement of snow layer melting. With low sprinkling density of the absorption material, the exposed snow surface, due to the gathering effect of the absorption material, brought about a decrease of the snow melting rate. On the other hand, with high sprinkling density of the absorption material, the snow melting rate also decreased due to increase of the thermal insulation effect of the absorption material. Useful nondimensional correlation equations for snow melting were derived in accordance with the ranges of various parameters. No potential conflict of interest relevant to this article was reported.

社団法人日本機械学会 Acta Medica Okayama 0387-5016 59 567 1993 熱放射による傾斜霜層の融解に関する基礎研究 270 277 EN Hideo Inaba Hideo Otake Akihiro Shigemori This paper deals with a new defrosting method in which a frost layer is melted by radiative heat energy as an energy source. The far-infrared radiative heat energy having a maximum wavelength of 5.5 μm is selected as the optimum radiative heat energy source for melting of the inclined frost-layer. The inclined frost-layer melting experiments using the radiative heat energy with a discharge of melted water on a cooling copper plate are carried out under various environmental parameters (inclination angle of frost-layer, radiative heat energy flux, air temperature, cooling brine temperature) including porosity of frost-layer as a frost structural factor. The dimensionless correlation equations which predict the time taken for complete frost-layer melting are derived as a function of various nondimensional frost-layer melting parameters. No potential conflict of interest relevant to this article was reported.

社団法人日本機械学会 Acta Medica Okayama 0387-5016 59 567 1993 静止水の過冷却現象に及ぼす諸因子の影響 255 262 EN Hideo Inaba Kengo Takeya Supercooling characteristics in quiescent bulk water enclosed in a circular tube were investigated on a basic level through numerous experiments. In the experiments, three kinds of water with different specific resistances were used as the test samples and their freezing temperatures were measured. The critical degree of supercooling depended on the property of the heat transfer surface and the cooling rate, and it became larger for a smoother surface and a higher cooling rate. It was found that the specific resistance of the water had little effect on the critical degree of supercooling . However, the insoluble particles included in the water greatly affected the ice nucleation in the supercooled water and the size effect of the insoluble particles was found to become important in the range of 0.1-1.0 μm in particle radius. For particle radii larger than this range, the critical degree of supercooling was independent of the size, while below this range it sharply increased with a decrease in the particle size. No potential conflict of interest relevant to this article was reported.