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Measurements and correlations of frictional single-phase and two-phase pressure drops of R-410A flow in small U-type return bends.

Author(s) : CHEN I. Y., WANG C. C., LIN S. Y.

Type of article: Article

Summary

This study presents single-phase and two-phase frictional data for R-410A in four U-type return bends with tube diameter, and curvature ratio and their frictional performances are investigated. The friction factor fC and two-phase pressure gradient in the return bend considerably increase with the decrease of curvature ratio. The significant increase of this ratio may be attributed to the change of flow pattern from stratified flow to annular flow. In contrast, the higher pressure gradient ratio at lower x was not observed. The flow pattern at low vapor quality is slug flow and no dramatic change of flow pattern across the return bend is seen. For the single-phase results, existing correlations give fair agreements with the present fC data. For two-phase results, the Geary correlation shows a better agreement with the data. A modified two-phase friction factor based on the Geary correlation is then proposed. The proposed correlation gives a good agreement to the present R410A data and Geary's R22 data with a mean deviation of 19.1%.

Details

  • Original title: Measurements and correlations of frictional single-phase and two-phase pressure drops of R-410A flow in small U-type return bends.
  • Record ID : 2004-2691
  • Languages: English
  • Source: International Journal of Heat and Mass Transfer - vol. 47 - n. 10-11
  • Publication date: 2004/05

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