Heat transfer, flow regime and instability of a nano- and micro-porous structure evaporator in a two-phase thermosyphon loop
2010 (English)In: International journal of thermal sciences, ISSN 1290-0729, Vol. 49, no 7, 1183-1192 p.Article in journal (Refereed) Published
Two-phase flow instabilities which may occur at low and high heat loads were studied for a thermosyphon loop with R134a as refrigerant. The heat transfer surface of the evaporator was enhanced with a copper nano- and micro-porous structure. The heat transfer of the enhanced evaporator was compared to a smooth surface evaporator. Finally, the influence of the liquid level and the inside diameter of the riser on the instability of the system have been investigated. It was found that the enhanced structure surface decreased the oscillations at the entire range of heat fluxes and enhanced the heat transfer coefficient. Three flow regimes were observed: Bubbly flow with nucleate boiling heat transfer mechanism, confined bubbly/churn flow with backflow and finally churn flow at high heat fluxes.
Place, publisher, year, edition, pages
2010. Vol. 49, no 7, 1183-1192 p.
Instability, Thermosyphon loop, Natural circulation, Heat transfer, Electronic cooling, Nano- and micro-porous structure surfaces
IdentifiersURN: urn:nbn:se:kth:diva-27545DOI: 10.1016/j.ijthermalsci.2010.01.016ISI: 000278233600013OAI: oai:DiVA.org:kth-27545DiVA: diva2:378894
QC 201012162010-12-162010-12-132011-11-11Bibliographically approved