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Research Papers: Evaporation, Boiling, and Condensation

# Flow Boiling of R134a and R134a/Propane Mixtures at Low Saturation Temperatures Inside a Plain Horizontal Tube

[+] Author and Article Information
A. Rabah1

Institut für Thermodynamik, Helmut-Schmidt Universität, Universität der Bundeswehr–Hamburg, Holstenhofweg 85, 22043 Hamburg, Germanyrabahss@hotmail.com

S. Kabelac

Institut für Thermodynamik, Helmut-Schmidt Universität, Universität der Bundeswehr–Hamburg, Holstenhofweg 85, 22043 Hamburg, Germany

1

Corresponding author.

J. Heat Transfer 130(6), 061501 (Apr 23, 2008) (9 pages) doi:10.1115/1.2897345 History: Received February 05, 2007; Revised July 17, 2007; Published April 23, 2008

## Abstract

Local heat transfer coefficients for flow boiling of pure 1,1,1,2-tetrafluoroethane (R134a) and binary mixtures of propane (R290) and R134a were measured. The experimental setup employed a vapor heated plain horizontal tube ($di=10mm$, $do=12mm$, $L=500mm$). The measurements covered a wide range of saturation temperatures $(233≤Ts≤278K)$, mass fluxes $(100≤ṁ≤300kg∕m2s)$, qualities $(0≤ẋ≤1)$, and concentrations $(0≤z̃≤0.65)$. In the zeotropic region of R134a/R290 mixtures, the measured local heat transfer coefficient was found to show a maximum decrease by a factor of 2 relative to that for pure R134a. At the azeotropic point (65% R290), it was found to increase by a factor of 1.2. The measured local heat transfer coefficients for both R134a and R134a/R290 were compared with a number of correlations.

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## Figures

Figure 1

Comparison of five different correlations with the experimental data of Kattan (4). Legend: ⋯ ⋯, Shah (8); –⋅⋅–, Gungor and Winterton (9); –⋅–⋅–, Kandlikar (10); – – –, Kattan (11); —, Steiner (7); ○, Kattan (4) experimental data.

Figure 2

(a) Experimental setup and (b) test section

Figure 3

Secondary evaporator loop for heating the test section

Figure 4

A phase diagram for the system R134a/R290 mixtures (open and closed symbols represent measured data for dew and bubble points, respectively)

Figure 5

The influence of the vapor quality on the local heat transfer coefficient of pure R134a

Figure 6

The influence of the vapor quality on the local heat transfer coefficient of pure R134a

Figure 7

The influence of the concentration on the local heat transfer coefficient for R134a/R290 mixtures

Figure 8

The influence of mass flux on the local heat transfer coefficient

Figure 9

Comparison of experimental data with Steiner (7) correlation for pure R134a

Figure 10

Comparison of Steiner correlation with the experimental data for R134a/R290 mixtures

Figure 11

Variation of the mean error with the bulk composition of R134a/R290 mixtures

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