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ACRC Technical Report 133PDF


Title:Heat Transfer and Pressure Drop Characteristics of R-22, R-134A and R-407C in Microchannel Tubes
Author(s):Vardan, A.; Dunn, W.E.
Subject(s):microchannel heat exchangers
Abstract:A study of heat transfer and pressure drop characteristics for single-phase and twophase flow of refrigerants in micro channel tubes was conducted. An existing facility was modified to perform tests on a single microchannel tube using water flowing in counterflow as the heat sink fluid. Data were collected for sub cooled liquid, superheated vapor and condensing refrigerant for circular-port microchannel tubes at four different mass flow rates. The refrigerants tested were R-22, R-134a and R-407C. In addition to circularport tubes, square-port tubes were tested with R-22 for both single-phase and two-phase flow. Data were also taken with water flowing inside a square-port microchannel tube. The Reynolds number for all the flows in this study ranged from 3,000 to 17,000 in the liquid phase and 30,000 to 110,000 in the vapor phase. The heat transfer coefficients and pressure drop for circular-port micro channel tubes were compared for R-22, R-134a and R-407C. For sub cooled liquid flow, the heat transfer coefficient for R-407C was found to be greater than that for R-22 and R-134a. The heat transfer coefficient for R-22 was found to slightly lesser than the other two refrigerants for condensing flow. A model was built to predict the heat transfer and pressure drop in the microchannel tube. In most cases, the heat transfer and pressure drop predicted by the model agree very well with experimental results. A sensitivity analysis revealed that the total heat transfer is not very sensitive to the refrigerant side heat transfer coefficient.
Issue Date:1997-11
Publisher:Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Air Conditioning and Refrigeration Center TR-133
Genre:Technical Report
Sponsor:Air Conditioning and Refrigeration Project 75
Date Available in IDEALS:2009-04-29
Identifier in Online Catalog:4165959

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