著者

野村 信福 中川 勝文

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.59, no.563, pp.2232-2237, 1993-07-25 (Released:2008-03-28)

参考文献数

23

被引用文献数

3 4

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Ultrasonic enhancement of heat transfer on a narrow surface was measured by changing the width of the surface from 8 to 0.1 mm. Ultrasonic power of 600 W with a frequency of 40 kHz was used. Heat transfer on the narrow surface without ultrasonic vibration was correlated by means of the experimental equation for thin wire. The cavitation intensity was measured by means of the cavitation erosion loss of aluminum foil of 15μm thickness. The effects of acoustic streaming and cavitation were separated by this measurement. Heat transfer by acoustic streaming was predicted through the forced convection. Enhancement by cavitation was explained by the turbulence heat conductivity of the microjets.

著者

野村 信福 中川 勝文

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.59, no.562, pp.2028-2034, 1993-06-25 (Released:2008-03-28)

参考文献数

16

被引用文献数

3 2

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The cavitation intensity and the heat transfer coefficient on the bottom surface of the object, by applying ultrasonic vibration, were measured experimentally. The object faced the ultrasonic generator adhered to the bottom of the water tank. The dimensions of the object were greater than the ultrasonic wavelength. Ultrasonic power of 600 W with a frequency of 40 kHz was used. The cavitation intensity was defined by the erosion loss of aluminum foil, whose thickness was 15 μm, when aluminum foil stuck on the bottom of the object was immersed into water in the ultrasonic field. The result was that the larger the cavitation intensity became, the more the heat transfer coefficient increased. With varying densities of objects, the greater the density was the larger the cavitation intensity.

著者

西嶋 春幸 定村 和佳 川村 洋介 中川 勝文

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.851, pp.17-00192-17-00192, 2017 (Released:2017-07-25)

参考文献数

13

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Recently, the refrigeration air conditioner and heat pump system using the two-phase flow ejector is beginning to appear, as the efficiency of the ejector cycle is improved largely in comparison with the conventional system. Shock and expansion waves can occur in the internal flow fields of the ejector, and the effect of the pressure fluctuation by those waves must be considered on the designs of the ejector. In this study, the pressure fluctuation of the shock wave appeared at the outlet of the two-phase flow nozzle are measured in the HFO1234yf refrigeration cycle. It was clarified by experiment that the amplification frequency components of pressure fluctuations are increased with the strength of the shock waves and the attenuation frequency components are increased with increase of liquid void fraction of downstream shock waves.