Numerical simulations of condensing R134a flows in horizontal pipes
File(s)
Author(s)
Type
Conference Paper
Abstract
Three-dimensional numerical simulations were performed of condensing R134a flows in a smooth horizontal pipe with an inner diameter of 8.4 mm and a length of 1.5 m, and validated against experimental results. A constant mass flux of 100 kg m-2 s-1 was considered and the influence of vapour qualities (0.25 to 0.75) and saturation temperatures (30 ?C and 40 ?C) on the resulting flow regimes and heat transfer characteristics of these flows were investigated. The volume-of-fluid (VOF) method was employed in the numerical framework to track and reconstruct the interface between the liquid and vapour phases. The simulations, given the imposed flow conditions, produced stratified wavy flow which are in agreement with the expected flow pattern based on the El Hajal flow pattern map. The heat transfer coefficient in the numerically simulated flows were found to be in good agreement (within 1.3%) with corresponding experimentally-measured values. From the simulations, the liquid-phase height at the bottom of the pipe was observed to be smaller with increasing vapour quality, which results in an increase in the heat transfer coefficient. A thicker film thickness and lower heat transfer coefficient were noted at the higher saturation temperature.
Date Issued
2019-04-14
Date Acceptance
2019-01-13
Citation
Proceedings of the 4th ASTFE Thermal and Fluids Engineering Conference (TFEC), 2019, 2019-April, pp.413-422
ISBN
978-1-56700-482-3
ISSN
2379-1748
Publisher
Begell House
Start Page
413
End Page
422
Journal / Book Title
Proceedings of the 4th ASTFE Thermal and Fluids Engineering Conference (TFEC)
Volume
2019-April
Copyright Statement
© 2019 Begell House.
Source
4th ASTFE Thermal and Fluids Engineering Conference (TFEC)
Subjects
Science & Technology
Physical Sciences
Technology
Thermodynamics
Engineering, Multidisciplinary
Engineering
transient
condensation
simulations
flow pattern
film thickness
heat transfer coefficient
HEAT-TRANSFER
2-PHASE FLOW
CONDENSATION
TUBES
PATTERN
Publication Status
Published
Start Date
2019-04-14
Finish Date
2019-04-17
Coverage Spatial
Las Vegas, NV, USA
Date Publish Online
2019-04-30