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ACRC Technical Report 221PDF


Title:Pressure Drop and Void Fraction in Microchannels Using Carbon Dioxide, Ammonia, and R245fa as Refrigerants
Author(s):Adams, D.C.; Hrnjak, P.S.; Newell, T.A.
Subject(s):void fraction
pressure drop
Abstract:Aluminum multi-port microchannels are currently utilized in automotive air conditioners for refrigerant condensation. In general, research activities are directed towards developing other air conditioning and refrigeration systems with microchannel condensers and evaporators by analyzing heat exchanger performance parameters of heat transfer, pressure drop, and void fraction. The purpose of this particular study is the experimental investigation of frictional pressure drop and void fraction in microchannels. Experiments are performed using 6-port and 14-port microchannels with hydraulic diameters of 1.54 mm and 1.02 mm, respectively. Fluids and saturation temperatures used in this experimentation include carbon dioxide at 15ºC, ammonia at 35ºC, and R245fa at 40ºC. Two-phase flow conditions include mass fluxes from 50 to 440 kg/s.m2 and qualities varying from 0 to 1. Experiments indicate that two-phase pressure drop and void fraction are dependent upon hydraulic diameter, mass flux, quality, and vapor density. Two-phase pressure drop is most significantly influenced by inertial force of the flow. Void fraction is strongly influenced by flow regime, which can be related to the vapor density of the refrigerant. In general, models exist to predict the experimental two-phase flow pressure drop and void fraction satisfactorily for specific conditions, but no comprehensive model has been formulated that encompasses the physical properties defining two-phase flow.
Issue Date:2003-12
Publisher:Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Air Conditioning and Refrigeration Center TR-221
Genre:Technical Report
Sponsor:Air Conditioning and Refrigeration Project 131
Date Available in IDEALS:2009-06-19

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