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NH3 in-tube condensation heat transfer and pressure drop in a smooth tube.

Condensación, transmisión de calor y caída de presión del NH3 en el interior de un tubo liso.

Author(s) : PARK C. Y., HRNJAK P.

Type of article: Article

Summary

This article is the Spanish translation of an article published in the International Journal of Refrigeration (see the Bulletin of the IIR, reference 2008-1526). This paper presents an overview of the issues and new results for in-tube condensation of ammonia in horizontal round tubes. A new empirical correlation is presented based on measured NH3 in-tube condensation heat transfer and pressure drop by Komandiwirya et al. An experimental investigation of pressure drop and heat transfer in an in-tube condensation system of ammonia with and without miscible oil in smooth and enhanced tubes. ACRC CR-54, University of Illinois at Urbana-Champaign] in an 8.1 mm aluminium tube at a saturation temperature of 35°C, and for a mass flux range of 20-270 kg m2/s. Most correlations over predict these measured NH3 heat transfer coefficients, up to 300%. The reasons are attributed to difference in thermophysical properties of ammonia compared to other refrigerants used in generation and validation of the correlations. Based on the conventional correlations, thermophysical properties of ammonia, and measured heat transfer coefficients, a new correlation was developed which can predict most of the measured values within plus or minus 20%. Measured NH3 pressure drop is shown and discussed. Two separated flow models are shown to predict the pressure drop relatively well at pressure drop higher than 1 kPa/m, while a homogeneous model yields acceptable values at pressure drop less than 1 kPa/m. The pressure drop mechanism and prediction accuracy are explained through the use of flow patterns.

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Pages: 10-22 (10 p.)

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Details

  • Original title: Condensación, transmisión de calor y caída de presión del NH3 en el interior de un tubo liso.
  • Record ID : 2009-1435
  • Languages: Spanish
  • Source: Frío Calor Aire acondicionado - vol. 37 - n. 416
  • Publication date: 2009/08

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