Flow boiling visualization of R-134a in a vertical channel of small diameter
2007 (English)In: 2007 Proceedings of the ASME/JSME Thermal Engineering Summer Heat Transfer Conference - HT 2007 Volume 1, 2007, 135-143 p.Conference paper (Refereed)
The present work reports on flow boiling visualization of refrigerant R-134a in a vertical circular channel with internal diameter of 1.33 mm and 23 5 mm in heated length. Quartz tube with a homogeneous ITO-coating is used allowing heating and simultaneous visualization. Flow patterns have been observed along the heated length with the aid of a digital camera with close-up lenses. From the flow boiling visualization, seven distinct two-phase flow patterns have been observed: Isolated bubbly flow, confined bubbly flow, slug flow, churn flow, slug-annular flow, annular flow, and mist flow. Two-phase flow pattern observations are presented in the form of flow pattern maps. Finally, the experimental flow pattern map is compared to models developed for conventional sizes as well as to a microscale map for air-water mixtures available in the literature, showing a large discrepancy.
Place, publisher, year, edition, pages
2007. 135-143 p.
IdentifiersURN: urn:nbn:se:kth:diva-41101ISI: 000254029000020ScopusID: 2-s2.0-43449096931ISBN: 978-0-7918-4274-4OAI: oai:DiVA.org:kth-41101DiVA: diva2:443822
7th ASME/JSME Thermal Engineering and Summer Heat Transfer Conference Location: Vancouver, Canada, Date: JUL 08-12, 2007