A New Approach Toward Low-Temperature Thermal Engineering Without Fluorocarbon Refrigerants

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1. Heat transfer and flow characteristics of two-phase flow in the microchannels (by K.Hijikata) : An experimental study on two-phase flow in microchannels has been conducted to identify the characteristics of flow and heat transfer. An array of 25 parallel michrochannels with the dimensions of 209 mum in height. 212 mum in width, and 9.96 mm in length for each one was manufactured on the stainless steel plate. The results showed that the friction factor for two-phase flow in the microchannels was smaller than that in conventional sized channels, and that the Nusselt number in the two-phase reached twice as large as that for liquid only. 2. High performance heat transfer in the absorption type refrigerator (by H.Inaba) : An experimental investigation on the adsorption/desorption characteristics of high performance organic fibrous absorbent, which was filled in the cylindrical absorption layr under a variety of densities, has been carried out. The results showed that the adsorption/deso … More rption characteristics of the absorbent in the present study is much better than that of conventional inorganic fibrous absorbent quantitatively. 3. Enhancement and Control of Heat Transfer by using a Multicomponent Medium (by A.Takimoto) : An analytical and experimental investigation on the micro-scale characteristics and the condensation heat transfer characteristics in the filmwise/droplet combined condensation has been carried out. A mixture of inorganic refrigerant and organic materials was adopted as the binary immiscibel liquid under the test. The predictions obtained in the present analytical model agree well with the experimental results. 4. Measurement of the Thermophysical Properties of the New Refrigerants. (by Y.Nagasaka) : The Liquid thermal cnductivity of the mixtures of HFC-32 and HFC-125 has been measured in the trmperature range 213K-293K and in the pressure range 2-30 Mpa with the HFC-32 mass fractions of 0.249,0.5,0.75 by using the transient hot-wire method with the precision of 0.5%. The solid thermal conductivity of HFC-32 and HFC125 has been also measured. 5. Control against the Growth of Frost by Utilizing the Electric Fields. (by M.Kumada) : In order to promote the defrosting and to control sagainst the frost growth, the effect of electric field on frosting phenomenon has been investigated experimentally. The effect of voltage, width of the pulse, and frequency on the defrosting was clarified, furthermore, the defrosting mechanism and the effect of the wettability of the surface was discussed. 6. Characteristics of Heat Exchanger Operating with Frosting and Defrosting (by K.Aoki) : The heat transfer characteristics and the performance of the heat exchanger with frosting/defrosting cycle have been investigated. Furthermore, the effect of the surface with ultra-high contact angle on the growth of the frost has been clarified experimentally. 7. Experimental study on the melting and flow characteristics of slush layr (by S.Fukusako) : An experim Less