Flow Boiling Heat Transfer of R134a in a Horizontal Smooth Tube: Experimental Results, Flow Patterns, and Assessment of Correlations

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F46747885%3A24210%2F22%3A00010117" target="_blank" >RIV/46747885:24210/22:00010117 - isvavai.cz</a>

Result on the web

<a href="http://doi.org/10.3390/en15207503" target="_blank" >http://doi.org/10.3390/en15207503</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/en15207503" target="_blank" >10.3390/en15207503</a>

Result language

angličtina

Original language name

Flow Boiling Heat Transfer of R134a in a Horizontal Smooth Tube: Experimental Results, Flow Patterns, and Assessment of Correlations

Original language description

This study presents an extensive evaluation of heat transfer characteristics, flow patterns, and pressure drop for saturation pressures ranging from 460–660 kPa in a horizontal smooth tube of 5 mm internal diameter using R134a as the working fluid. The effect of saturation pressures for mass fluxes of 150–300 kg/m2s and heat fluxes of 8.26–23.3 kW/m2 which are typical of refrigeration and air conditioning applications are also investigated. Flow patterns observed during the study are predicted with a well-known flow pattern map of Wojtan et al. The experimental results are compared with seven (7) correlations developed based on different theories to find which correlation best predicts the experimental data. The results show that, at low mass flux, increasing saturation pressure results in an increased heat transfer coefficient. This effect is more pronounced in the low vapor quality region and the dominant mechanism is nucleate boiling. At high mass flux, increasing saturation pressure leads to an insignificant increase in the heat transfer coefficient. At this high mass flux but low heat flux, the heat transfer coefficient increases with vapor quality, indicating convective boiling dominance. However, for high heat flux, the heat transfer coefficient is linear over vapor quality, indicating nucleate boiling dominance. Pressure drop is observed to decrease with increasing saturation pressure. Increasing saturation pressure increases the vapor quality at which the flow pattern transitions from intermittent flow to annular flow. The flow patterns predicted are a mixture of slug and stratified wavy and purely stratified wavy for low mass fluxes. For increased mass fluxes, the flow patterns predicted are slug, intermittent, annular, and dryout. Cooper’s model was the best predictor of the experimental data and the trend of heat transfer.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

20704 - Energy and fuels

Project

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Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2022

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Energies

ISSN

1996-1073

e-ISSN

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Volume of the periodical

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Issue of the periodical within the volume

October

Country of publishing house

CH - SWITZERLAND

Number of pages

23

Pages from-to

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UT code for WoS article

000872518900001

EID of the result in the Scopus database

2-s2.0-85140765998