• 제목/요약/키워드: 수직평활관

검색결과 2건 처리시간 0.017초

외경 5mm 수직 평활관 및 마이크로핀관 내의 이산화탄소/프로판 혼합냉매의 증발열전달 특성에 관한 실험적 연구 (An Experimental Study on the Evaporative Heat Transfer Characteristics of $CO_2$/Propane Mixtures Flowing Upward in Vertical Smooth and Micro-fin Tubes with an Outer Diameter of 5 mm)

  • 조진민;김민수
    • 설비공학논문집
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    • 제21권4호
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    • pp.243-251
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    • 2009
  • Refrigerant mixtures provide an opportunity to adjust their properties to fit design criteria and a possibility to create new blends that can improve heat transfer characteristics. Therefore, mixture of $CO_2$ and propane is chosen which may be a promising refrigerant and has good environmental compatibility. This paper presents measured heat transfer coefficient data during evaporation process of $CO_2$/propane mixtures flowing upward in vertical smooth and. micro-fin tubes. Smooth and micro-fin tubes with outer diameters of 5 mm and length of 1.44in were selected as test tubes. The tests were conducted at mass fluxes of 212 to $656kg/m^{2}s$, inlet temperatures of -10 to $30^{\circ}C$, heat fluxes of 15 to $60\;kW/m^2$ and for several compositions (75/25, 50/50, 25/75 wt%). Among $CO_2$/propane refrigerant mixtures, the heat transfer characteristics are much better than that of any compositions when the composition is 75/25 (wt%).

이산화탄소의 수직원관 내 상향유동 증발열전달 특성에 관한 연구 (A study on the characteristics of evaporation heat transfer of carbon dioxide flowing upward in a vertical smooth tube)

  • 김용진;조진민;김민수
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회B
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    • pp.2217-2221
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    • 2007
  • Because of the ozone layer depletion and global warming, new alternative refrigerants are being developed. In this study, evaporation heat transfer characteristics of carbon dioxide flowing upward in a vertical tube have been investigated by experiment. Before the test section, a pre-heater is installed to adjust the inlet quality of the refrigerant to a desired value. A smooth tube with outer diameter of 5 mm and length of 1.44 m was selected as a test tube. The test was conducted at mass fluxes of 212 to 530 kg/$m^2s$, saturation temperature of -5 to 20$^{\circ}C$, and heat fluxes of 20 to 45 kW/$m^2$. As the vapor quality and mass fluxes increase, the heat transfer coefficients of carbon dioxide are decreased, and the heat transfer coefficients increase when the heat fluxes and saturation temperatures increase.

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