University of Illinois Urbana-Champaign

Characterization of Two-Phase Flow in Microchannels

Nino, V.G.; Hrnjak, P.S.; Newell, T.A.

Content Files
TR202.pdf

Permalink

https://hdl.handle.net/2142/12055

Description

Title
Characterization of Two-Phase Flow in Microchannels
Author(s)
  • Nino, V.G.
  • Hrnjak, P.S.
  • Newell, T.A.
Issue Date
2002-10
Keyword(s)
  • void fraction
  • pressure drop
  • microchannels
Date of Ingest
2009-06-04T22:53:36Z
Abstract
Aluminum multi-port microchannel tubes are currently utilized in automotive air conditioners for refrigerant condensation. Recent research activities are directed toward developing other air conditioning and refrigeration systems with microchannel condensers and evaporators. Three parameters are necessary to analyze a heat exchanger performance: heat transfer, pressure drop, and void fraction. The purpose of this investigation is the experimental investigation of void fraction and frictional pressure drop in microchannels. A flow visualization analysis is another important goal for two-phase flow behavior understanding and experimental analysis. Experiments were performed with a 6-port and a 14-port microchannel with hydraulic diameters of 1.54 mm and 1.02 mm, respectively. Mass fluxes from 50 to 300 kg/s.m2 (range of most typical automotive applications) are operated, with quality ranging from 0% to 100% for two-phase flow experiments. R410A, R134a, and air-water mixtures are used as primary fluids. The results from the flow visualization studies indicate that several flow configurations may exist in multi-port microchannel tubes at the same time while constant mass flux and quality flow conditions are maintained. Flow mapping of the fluid regimes is accomplished by developing functions that describe the fraction of time or the probability that the fluid exists in an observed flow configuration. Experimental analysis and flow observations suggest that pressure drop and void fraction in microchannel is dependent on the most probable flow regime at which the two-phase mixture is flowing. In general, correlations for void fraction and pressure drop predictions are based in a separated flow model and do not predict the experimental results in the range of conditions investigated. A flow regime based model is developed for pressure drop and void fraction predictions in microchannels.
Publisher
Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report Name or Number
Air Conditioning and Refrigeration Center TR-202
Type of Resource
text
Genre of Resource
Technical Report
Language
en
Permalink
http://hdl.handle.net/2142/12055
Sponsor(s)/Grant Number(s)
Air Conditioning and Refrigeration Project 107

Owning Collections

Technical Reports - Air Conditioning and Refrigeration Center PRIMARY