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An Experimental Investigation on Bubbles Departure Characteristics during Sub-Cooled Flow Boiling in a Vertical U-Shaped Channel Utilizing High-Speed Photography

Ghazanfari Holagh, Shahriyar, Abdous, Mohammad Ali, Roy, Prosun, Shamsaiee, Masood, Shafiee, Mahmood, Saffari, Hamid, Valiño, Luis, Andersson, Ronnie (2021) An Experimental Investigation on Bubbles Departure Characteristics during Sub-Cooled Flow Boiling in a Vertical U-Shaped Channel Utilizing High-Speed Photography. Thermal Science and Engineering Progress, 22 . Article Number 100828. ISSN 2451-9049. (doi:10.1016/j.tsep.2020.100828) (Access to this publication is currently restricted. You may be able to access a copy if URLs are provided) (KAR id:85704)

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https://doi.org/10.1016/j.tsep.2020.100828

Abstract

Classified as a passive heat transfer enhancement technique, U-shaped channels are commonly encountered with applications associated with boiling heat transfer such as air conditioning systems, evaporators, and boilers. On the other hand, understanding heat transfer in flow boiling is heavily dependent upon bubbles dynamic behavior, which is influenced by flow and geometrical conditions. In this paper, bubbles departure characteristics are experimentally studied in upward sub-cooled flow boiling of distilled water in a vertical U-shaped channel. The influence of flow conditions, embracing heat flux, mass flux, and inlet sub-cooling on bubbles characteristics, encompassing departure diameter, growth and waiting times, and nucleation frequency, is investigated through conducting 68 experiments. All the experiments are carried out at atmospheric pressure over a Nichrome heating surface installed on the outer wall of the channel, with heat flux, mass flux, and inlet flow temperature in the ranges of 26.1–61.5 kW.m―2, 114–255 kg.m-2s-1, and 1 to 8°C. A high-speed camera is utilized to capture bubbles growth process and departure instance. The results reveal that as wall heat flux increases and mass flux and inlet sub-cooling decrease, bubbles departure diameter and frequency rise, while waiting time declines. Also, lower growth times are detected when wall heat flux and mass flux increase and inlet sub-cooling declines. Two new correlations are developed to predict present and previously published experimental data of departure diameter and nucleation frequency with mean standard deviations of 18.0% and 18.5%, correspondingly.

Item Type: Article
DOI/Identification number: 10.1016/j.tsep.2020.100828
Uncontrolled keywords: Sub-cooled flow boiling; U-shaped channel; Departure diameter; Nucleation frequency; Growth time; Waiting time
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Engineering and Digital Arts
Depositing User: Mahmood Shafiee
Date Deposited: 27 Jan 2021 22:26 UTC
Last Modified: 16 Feb 2021 14:17 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/85704 (The current URI for this page, for reference purposes)
Shafiee, Mahmood: https://orcid.org/0000-0002-6122-5719
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