An experimental study of condensed convective flow patterns in the downward U-shaped tubes with different inclinations

Moslem Mozafari, M. A. Akhavan-Behabadi, M. Jamali-Ashtiani

Research output: Contribution to conferencePaperpeer-review

Abstract

In this study, two-phase flow patterns and transition zones of the patterns in the condensation process of the refrigerant R-134a in the U-shaped tubes vertically downwards were experimentally investigated. The tests were conducted with seven different inclination angles (angle between the velocity vector of the refrigerant and the horizontal plane in returned inlet U-shaped tube, the trigonometric -90 to +90) with intervals of 30º, in the range of mass velocities from 52 to 225. According to the experiments, it was found that the angular position of the U-shaped tube has a significant impact on the distribution of the condensed liquid and vapor. Annular flow, quasi-annular, intermittent and wavy Slug/segregated patterns, were observed at the inclination angles -90 and - 60. Annular flow, annular-wavy and periodic patterns were observed at inclination angles -30 to +60. In addition, stratified flow and stratified-wavy flow patterns were also observed with zero-degree inclination angle and the slug flow pattern was also seen with inclination angle +30 and +60. Annular flow, annular-wavy, distributed and Slug regimes were also observed with inclination angle +90. In this research, the internal diameter of the tube and the average diameter of the returned bend of the U-shaped tube were 747/7 mm and 55 mm, respectively.
Original languageEnglish
Pages60
Number of pages1
Publication statusPublished - 2014
Externally publishedYes
EventThe 5th International Conference on Heating, Ventilating and Air Conditioning - Tehran, Iran, Islamic Republic of
Duration: 10 Jun 201412 Jun 2014

Conference

ConferenceThe 5th International Conference on Heating, Ventilating and Air Conditioning
Abbreviated titleICHVAC 5
CountryIran, Islamic Republic of
CityTehran
Period10/06/1412/06/14

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