Advanced Thermosyphon Cooling with Nanoporous Structured Mini Channel Evaporators
2010 (English)In: PROCEEDINGS OF THE ASME MICRO/NANOSCALE HEAT AND MASS TRANSFER INTERNATIONAL CONFERENCE, VOL 3, NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2010, 183-189 p.Conference paper (Refereed)
Attention has been given to enhance boiling surfaces in order to decrease the temperature difference and to increase heat transfer coefficient. Structured surfaces may provide both surface enlargement and artificial nucleation sites, thus ameliorate the heat transfer coefficient. The goal of the present experimental work is to analyze the influence on heat transfer coefficient (HTC) of enhanced surface structures coated on mini channel heat exchanger working in a closed loop thermosyphon system. Experimental tests were carried out with three types of surface enhanced mini channel evaporators: smooth surface, threaded structure and nanoporous coating. The evaporators are single channel half circularly shaped, adapted for filming purpose, measuring 30mm in length and 3mm in diameter. Surface areas of channels are 1.41cm(2). Experiments were conducted in refrigerant 134a at 4.87bar (reduced pressure pr=0.12) and at heat fluxes ranging from 0.7W/cm(2) to 63.8W/cm(2). A high speed video camera was used for visualization of the two-phase flow in the evaporator channel. It is shown that threaded surface provides the highest heat transfer coefficient (HTC) from no load to heat flux of 7.1W/cm(2), the nanoporous structure shows the highest performance between 7.1W/cm(2) and 49.6W/cm(2), and the smooth surface channel exhibits the best HTC from 49.6W/cm(2) and higher. In this paper, the influences of heat flux and surface structures on HTC are discussed, and the impact of refrigerant flow regimes on heat transfer performance is also highlighted.
Place, publisher, year, edition, pages
NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2010. 183-189 p.
Enhanced Boiling, Flow Pattern, Mini Channel, Nano Structure, Thermosyphon Cooling, Threaded Surface
IdentifiersURN: urn:nbn:se:kth:diva-34668DOI: 10.1115/MNHMT2009-18251ISI: 000290920600026ScopusID: 2-s2.0-77954316693ISBN: 978-0-7918-4391-8OAI: oai:DiVA.org:kth-34668DiVA: diva2:423552
ASME Micro/Nanoscale Heat and Mass Transfer International Conference, Shanghai, PEOPLES R CHINA, DEC 18-21, 2009
QC 201106152011-06-152011-06-132011-06-15Bibliographically approved