Evaporation Heat Transfer and Pressure Drop of $CO_2$ in a Small diameter Tube

세관내 이산화탄소의 증발 열전달 및 압력강화

  • 장승일 (부경대학교 냉동공조공학과) ;
  • 최선묵 (부경대학교 냉동공조공학과) ;
  • 김대희 (부경대학교 냉동공조공학과) ;
  • 박기원 (여수대학교 냉동공조공학과) ;
  • 오후규 (부경대학교 냉동공조공학과)
  • Published : 2005.06.26

Abstract

The evaporation heat transfer and pressure drop of $CO_2$ in a small diameter tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator(test section). The test section was made of a horizontal stainless steel tube with the inner diameter of 4.57 mm, and length of 4 m. The experiments were conducted at mass flux of 200 to 700 $kg/m^2s$, saturation temperature of $0^{\circ}C$ to $20^{\circ}C$, and heat flux of 10 to 20 $kW/m^2$ . The test results showed the evaporation heat transfer of $CO_2$ has great effect on more nucleate boiling than convective boiling. The evaporation heat transfer coefficients of $CO_2$ are highly dependent on the vapor quality, heat flux and saturation temperature. The evaporation pressure drop of C02 are highly dependent on the mass flux. In comparison with test results and existing correlations, correlations failed to predict the evaporation heat transfer coefficient and pressure drop of $CO_2$, therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient and friction pressure drop of $CO_2$ in a horizontal tube.

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