Experimental Study of Non-Adiabatic Flow of Refrigerant R-134a in a Capillary Tube

Greenfield, K.P.

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https://hdl.handle.net/2142/10981 Copy

Description

Title

Experimental Study of Non-Adiabatic Flow of Refrigerant R-134a in a Capillary Tube

Author(s)

Greenfield, K.P.

Contributor(s)

Dunn, W.E.

Issue Date

1994-09

Keyword(s)

capillary-tube model

Abstract

This thesis describes the development of an experimental facility for testing capillary-tube expansion devices and presents preliminary data for flow of R-134a in a non-adiabatic capillary tube. The capillary tube is the expansion device of choice in domestic refrigerators and some other refrigeration systems because of its simplicity and low cost. However, two-phase flow phenomena in capillary tubes are complex. New energy efficiency requirements and the advent of the Montreal . Protocol which mandates the replacement of CFC refrigerants such as R-12 with alternatives such as HFC refrigerant R-134a, have combined to create a need for more extensive research on the flow characteristics in capill.ary tubes. A literature review reveals that little progress has been made since the 1950's in predicting the behavior of capillary-tube flow accurately. Data for non-adiabatic operation and for capillary tubes using R-134a are scarce. Most experimentation has been geared toward validating specific rather than gathering data for conditions actually seen in domestic refrigerators. Attempts to model capillary-tube characteristics such as the metastable region, two-phase friction factors and tube wall roughness, critical flow, and two-phase flow regimes have met with limited success. An experimental facility is presented which is designed to acquire data for conditions including those seen in domestic refrigerators. The facility has capability for independent control of oil concentration, multiple test-section configurations, and instrumentation for gathering mass-flow, pressure, and temperature data. Also presented is a small set of data used to analyze the performance of the experimental facility and suggest topics for further investigation.

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-67

Type of Resource

text

Language

en

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http://hdl.handle.net/2142/10981

Sponsor(s)/Grant Number(s)

Air Conditioning and Refrigeration Center Project 21

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