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Title: Two-phase frictional pressure drop of R-134a and R-410A refrigerant-oil mixtures in straight tubes and U-type wavy tubes

Abstract

This study presents single-phase and two-phase pressure drop data for R-134a/oil mixture flowing in a wavy tube with inner diameter of D=5.07mm and curvature ratio 2R/D=5.18 and R-410A/oil mixture flowing in a wavy tube of D=3.25mm and 2R/D=3.91. Both mixtures have oil concentration C=0%, 1%, 3% and 5% for the tests. The ratio of frictional factor between U-bend in wavy tube and straight tube (f{sub C}/f{sub S}) is about 3.5 for Re<2500 and is approximate 2.5 for Re=3500-25,000 for oil and liquid R-134a mixture flowing in the 5.07mm diameter wavy tube. The influence of oil concentration on single-phase friction factor is negligible, provided that the properties are based on the mixture of lubricant and refrigerant. The ratio between two-phase pressure gradients of U-bend and straight tube is about 2.5-3.5. This ratio is increased with oil concentration and vapor quality. The influence of oil is augmented at a higher mass flux for liquid spreading around the periphery at an annular flow pattern. Moreover, the influence of lubricant becomes more evident of a U-bend configuration. This is associated the induced swirled flow motion and an early change of flow pattern from stratified to annular flow pattern. The frictional two-phase multiplier for straightmore » tube can be fairly correlated by using the Chisholm correlation for the data having Martinelli parameter X between 0.05 and 1.0. Fridel correlation also shows a good agreement with a mean deviation of 17.6% to all the straight tube data. For the two-phase pressure drop in U-bend, the revised Geary correlation agrees very well with the R-134a and R-410A oil-refrigerant data with a mean deviation of 16.4%. (author)« less

Authors:
;  [1]; ;  [2]
  1. Mechanical Engineering Department, National Yunlin University of Science and Technology, Yunlin 640 (Taiwan)
  2. Energy and Resource Laboratories, Industrial Technology Research Institute Hsinchu 310 (Taiwan)
Publication Date:
OSTI Identifier:
20843288
Resource Type:
Journal Article
Resource Relation:
Journal Name: Experimental Thermal and Fluid Science; Journal Volume: 31; Journal Issue: 4; Other Information: Elsevier Ltd. All rights reserved
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; AIR CONDITIONERS; HEAT PUMPS; FRICTION; PRESSURE DROP; LUBRICATING OILS; REFRIGERANTS; TWO-PHASE FLOW; MIXTURES; TUBES; CONFIGURATION

Citation Formats

Chen, Ing Youn, Wu, Yu-Shi, Chang, Yu-Juei, and Wang, Chi-Chuan. Two-phase frictional pressure drop of R-134a and R-410A refrigerant-oil mixtures in straight tubes and U-type wavy tubes. United States: N. p., 2007. Web. doi:10.1016/J.EXPTHERMFLUSCI.2006.05.001.
Chen, Ing Youn, Wu, Yu-Shi, Chang, Yu-Juei, & Wang, Chi-Chuan. Two-phase frictional pressure drop of R-134a and R-410A refrigerant-oil mixtures in straight tubes and U-type wavy tubes. United States. doi:10.1016/J.EXPTHERMFLUSCI.2006.05.001.
Chen, Ing Youn, Wu, Yu-Shi, Chang, Yu-Juei, and Wang, Chi-Chuan. Thu . "Two-phase frictional pressure drop of R-134a and R-410A refrigerant-oil mixtures in straight tubes and U-type wavy tubes". United States. doi:10.1016/J.EXPTHERMFLUSCI.2006.05.001.
@article{osti_20843288,
title = {Two-phase frictional pressure drop of R-134a and R-410A refrigerant-oil mixtures in straight tubes and U-type wavy tubes},
author = {Chen, Ing Youn and Wu, Yu-Shi and Chang, Yu-Juei and Wang, Chi-Chuan},
abstractNote = {This study presents single-phase and two-phase pressure drop data for R-134a/oil mixture flowing in a wavy tube with inner diameter of D=5.07mm and curvature ratio 2R/D=5.18 and R-410A/oil mixture flowing in a wavy tube of D=3.25mm and 2R/D=3.91. Both mixtures have oil concentration C=0%, 1%, 3% and 5% for the tests. The ratio of frictional factor between U-bend in wavy tube and straight tube (f{sub C}/f{sub S}) is about 3.5 for Re<2500 and is approximate 2.5 for Re=3500-25,000 for oil and liquid R-134a mixture flowing in the 5.07mm diameter wavy tube. The influence of oil concentration on single-phase friction factor is negligible, provided that the properties are based on the mixture of lubricant and refrigerant. The ratio between two-phase pressure gradients of U-bend and straight tube is about 2.5-3.5. This ratio is increased with oil concentration and vapor quality. The influence of oil is augmented at a higher mass flux for liquid spreading around the periphery at an annular flow pattern. Moreover, the influence of lubricant becomes more evident of a U-bend configuration. This is associated the induced swirled flow motion and an early change of flow pattern from stratified to annular flow pattern. The frictional two-phase multiplier for straight tube can be fairly correlated by using the Chisholm correlation for the data having Martinelli parameter X between 0.05 and 1.0. Fridel correlation also shows a good agreement with a mean deviation of 17.6% to all the straight tube data. For the two-phase pressure drop in U-bend, the revised Geary correlation agrees very well with the R-134a and R-410A oil-refrigerant data with a mean deviation of 16.4%. (author)},
doi = {10.1016/J.EXPTHERMFLUSCI.2006.05.001},
journal = {Experimental Thermal and Fluid Science},
number = 4,
volume = 31,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}