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The heat transfer characteristics of supercritical $CO_2$ in a horizontal tube  

Oh Hoo-Kyu (부경대학교 냉동공학과)
Lee Dong-Geon (부경대학교 냉동공학과 대학원)
Son Chang-Hyo (부경대학교 냉동공학과 대학원)
Publication Information
Journal of Advanced Marine Engineering and Technology / v.29, no.5, 2005 , pp. 526-532 More about this Journal
Abstract
The cooling heat transfer coefficient of $CO_2$(R-744) in a horizontal 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 gas cooler(test section). The test section consists of a smooth, horizontal stainless steel tube of 7.75 mm inner diameter. The experiments were conducted at mass flux of 200 to $400\;kg/m^{2}s$ and the inlet cooling pressure of 7.5 MPa to 10.0 MPa. The variation of heat transfer coefficient tends to decrease as cooling pressure of $CO_2$ increases. The heat transfer coefficient with respect to mass flux increases as mass flux increases. The pressure drop of $CO_2$ in the gas cooler shows a relatively good agreement with that predicted by Blasius's correlation. The local heat transfer coefficient of $CO_2$ agrees well with the correlation by Bringer-Smith.
Keywords
R-744; Gas cooler; Heat pump; Heat transfer coefficient of CO2;
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