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contributor authorGregory J. Michna
contributor authorEric A. Browne
contributor authorYoav Peles
contributor authorMichael K. Jensen
date accessioned2017-05-09T00:33:33Z
date available2017-05-09T00:33:33Z
date copyrightNovember, 2009
date issued2009
identifier issn0022-1481
identifier otherJHTRAO-27874#111402_1.pdf
identifier urihttp://yetl.yabesh.ir/yetl/handle/yetl/140937
description abstractAn investigation of the pressure drop and impingement zone heat transfer coefficient trends of a single-phase microscale impinging jet was undertaken. Microelectromechanical system (MEMS) processes were used to fabricate a device with a 67-μm orifice. The water jet impinged on an 80-μm square heater on a normal surface 200 μm from the orifice. Because of the extremely small heater area, the conjugate convection-conduction heat transfer process provided an unexpected path for heat losses. A numerical simulation was used to estimate the heat losses, which were quite large. Pressure loss coefficients were much higher in the range Red,o<500 than those predicted by available models for short orifice tubes; this behavior was likely due to the presence of the wall onto which the jet impinged. At higher Reynolds numbers, much better agreement was observed. Area-averaged heat transfer coefficients up to 80,000 W/m2 K were attained in the range 70<Red<1900. This corresponds to a 400 W/cm2 heat flux at a 50°C temperature difference. However, this impingement zone heat transfer coefficient is nearly an order-of-magnitude less than that predicted by correlations developed from macroscale jet data, and the dependence on the Reynolds number is much weaker than expected. Further investigation of microjet heat transfer is needed to explain the deviation from expected behavior.
publisherThe American Society of Mechanical Engineers (ASME)
titleSingle-Phase Microscale Jet Stagnation Point Heat Transfer
typeJournal Paper
journal volume131
journal issue11
journal titleJournal of Heat Transfer
identifier doi10.1115/1.3154750
journal fristpage111402
identifier eissn1528-8943
keywordsPressure
keywordsTemperature
keywordsHeat transfer
keywordsMicroscale devices
keywordsHeat losses
keywordsPressure drop
keywordsWater
keywordsHeat transfer coefficients
keywordsReynolds number
keywordsFlow (Dynamics)
keywordsJets
keywordsFluids AND Convection
treeJournal of Heat Transfer:;2009:;volume( 131 ):;issue: 011
contenttypeFulltext


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