Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
662332 | International Journal of Heat and Mass Transfer | 2008 | 15 Pages |
Abstract
This article is the first in a three part study on flow boiling of refrigerants R236fa and R245fa in a silicon multi-microchannel heat sink. The heat sink was composed of 67 parallel channels, which are 223 μm wide, 680 μm high and 20 mm long with 80 μm thick fins separating the channels. The base heat flux was varied from 3.6 to 221 W/cm2, the mass velocity from 281 to 1501 kg/m2 s and the exit vapour quality from 2% to 75%. The working pressure and saturation temperature were set nominally at 273 kPa and 25 °C, respectively. The present database includes 1217 local heat transfer coefficient measurements, for which three different heat transfer trends were identified, but in most cases the heat transfer coefficient increased with heat flux and was almost independent of vapour quality and mass velocity. Importantly, it was found for apparently the first time that the heat transfer coefficient as a function of vapour quality reaches a maximum at very high heat fluxes and then decreases with further increase of heat flux.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
Bruno Agostini, John Richard Thome, Matteo Fabbri, Bruno Michel, Daniele Calmi, Urs Kloter,