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Flow boiling of refrigerant-oil mixtures; Transferts de chaleur dans un melange constitue de fluide frigorigene et d'huile

Abstract

The phase out of chlorine containing refrigerants (CFC and HCFC) has led to the introduction of new refrigerants and lubricants to the market. The interest in using HFC fluids as working fluids to replace fluids harmful to the stratospheric ozone layer. The study presents the influence of synthetic oil (POE ISO 68) on flow boiling of refrigerants R134a (pure fluid) and R410A (R32/R125 50%/50%). Local and average heat transfer coefficients and pressure drops have been measured for a smooth horizontal tube. The distribution of the heat transfer coefficient at the inner wall has been obtained from solving the inverse heat conduction problem (IHCP) and resulted in a local combination of nucleate and convective contributions to flow boiling. Local heat transfer coefficients have been averaged and displayed as a function of the vapour quality. For R134a: small amounts of oil (1% to 6%) in the liquid phase increased the heat transfer coefficient at low and intermediate vapour qualities (less than 0.60) compared to pure fluid. However a hugh reduction of the heat transfer has been observed at higher vapour qualities. For R410A : oil dramatically decreases the heat transfer coefficient compared to pure fluid. Pressure drops are also affected by small  More>>
Authors:
Publication Date:
Oct 13, 1999
Product Type:
Thesis/Dissertation
Report Number:
FRCEA-TH-791
Reference Number:
EDB-01:043407
Resource Relation:
Other Information: TH: These energetique; PBD: 13 Oct 1999
Subject:
42 ENGINEERING; CHLOROFLUOROCARBONS; OZONE LAYER; GREENHOUSE EFFECT; HEAT TRANSFER; OPTIMIZATION; FORCED CONVECTION; NUCLEATE BOILING; NUCLEATION; HEAT EXCHANGERS; PHYSICAL PROPERTIES; TWO-PHASE FLOW; PRESSURE DROP; REFRIGERANTS; LUBRICANTS; RESEARCH PROGRAMS
OSTI ID:
20133870
Research Organizations:
CEA/Grenoble, Dept. de Thermohydraulique et de Physique (DTP), 38 (France); Universite Henri Poincare, 54 - Vandoeuvre-les-Nancy (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR0104100
Availability:
Available to ETDE participating countries only(see www.etde.org); commercial reproduction prohibited; OSTI as DE20133870
Submitting Site:
FR
Size:
208 pages
Announcement Date:

Citation Formats

Feidt, M. Flow boiling of refrigerant-oil mixtures; Transferts de chaleur dans un melange constitue de fluide frigorigene et d'huile. France: N. p., 1999. Web.
Feidt, M. Flow boiling of refrigerant-oil mixtures; Transferts de chaleur dans un melange constitue de fluide frigorigene et d'huile. France.
Feidt, M. 1999. "Flow boiling of refrigerant-oil mixtures; Transferts de chaleur dans un melange constitue de fluide frigorigene et d'huile." France.
@misc{etde_20133870,
title = {Flow boiling of refrigerant-oil mixtures; Transferts de chaleur dans un melange constitue de fluide frigorigene et d'huile}
author = {Feidt, M}
abstractNote = {The phase out of chlorine containing refrigerants (CFC and HCFC) has led to the introduction of new refrigerants and lubricants to the market. The interest in using HFC fluids as working fluids to replace fluids harmful to the stratospheric ozone layer. The study presents the influence of synthetic oil (POE ISO 68) on flow boiling of refrigerants R134a (pure fluid) and R410A (R32/R125 50%/50%). Local and average heat transfer coefficients and pressure drops have been measured for a smooth horizontal tube. The distribution of the heat transfer coefficient at the inner wall has been obtained from solving the inverse heat conduction problem (IHCP) and resulted in a local combination of nucleate and convective contributions to flow boiling. Local heat transfer coefficients have been averaged and displayed as a function of the vapour quality. For R134a: small amounts of oil (1% to 6%) in the liquid phase increased the heat transfer coefficient at low and intermediate vapour qualities (less than 0.60) compared to pure fluid. However a hugh reduction of the heat transfer has been observed at higher vapour qualities. For R410A : oil dramatically decreases the heat transfer coefficient compared to pure fluid. Pressure drops are also affected by small amounts of lubricant: an important increase has been noted for both fluids. Available design methods for flow boiling heat transfer coefficient (superposition, enhancement, asymptotic) badly predict the experimental results. Nevertheless a new design method accounting for flow patterns has shown good agreements. The influence of the lubricant on the heat transfer is discussed and a new proposition is made to calculate pressure drops. (author)}
place = {France}
year = {1999}
month = {Oct}
}