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Experimental studies on the evaporative heat transfer and pressure drop of CO2 in smooth and micro-fin tubes of the diameters of 5 and 9.52 mm.

Author(s) : CHO J. M., KIM M. S.

Type of article: Article, IJR article

Summary

Carbon dioxide among natural refrigerants has gained a considerable attention as an alternative refrigerant due to its excellent thermophysical properties. In-tube evaporation heat transfer characteristics of carbon dioxide were experimentally investigated and analyzed as a function of evaporating temperature, mass flux, heat flux and tube geometry. Heat transfer coefficient data during evaporation process of carbon dioxide were measured for 5 m long smooth and micro-fin tubes with outer diameters of 5 and 9.52 mm. The tests were conducted at mass fluxes of from 212 to 656 kg/m2.s, saturation temperatures of from 0 to 20°C and heat fluxes of from 6 to 20 kW/m2. The difference of heat transfer characteristics between smooth and micro-fin tubes and the effect of mass flux, heat flux, and evaporation temperature on enhancement factor and penalty factor were presented. Average evaporation heat transfer coefficients for a micro-fin tube were approximately 150-200% for 9.52 mm OD tube and 170-210% for 5 mm OD tube higher than those for the smooth tube at the same test conditions. The effect of pressure drop expressed by measured penalty factor of 1.2-1.35 was smaller than that of heat transfer enhancement.

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Pages: 986-994

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Details

  • Original title: Experimental studies on the evaporative heat transfer and pressure drop of CO2 in smooth and micro-fin tubes of the diameters of 5 and 9.52 mm.
  • Record ID : 2007-2516
  • Languages: English
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 30 - n. 6
  • Publication date: 2007/09

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