Transient microscale flow boiling heat transfer characteristics of HFE-7000. (November 2015)

• Record Type: Journal Article
• Authors: Basu, Saptarshi; Werneke, Brian; Peles, Yoav; Jensen, Michael K.
• Is Part Of: International journal of heat and mass transfer. Volume 90(2015:Nov.)
• Page Start: 396
• Page End: 405
• Publication Date: 2015-11
• Subjects: Microscale -- Flow boiling -- Transient -- HFE-7000; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2015.06.038
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Transient flow boiling of HFE-7000 in thermal microdevice. Experimental study of boiling dynamics and heat transfer characteristics. Transient inputs: step change in heat flux and rectangular pulse. Onset of boiling conditions and repeatability investigated. High speed visualization and measurement of bubble dynamics. Abstract: A detailed experimental study was conducted to identify the important parametric trends governing the temperature response of a microdevice to transient heat loads for flow boiling of HFE-7000. The microdevice consisted of a microgap etched on a silicon wafer and placed centrally over a thin-film heater deposited on a Pyrex wafer. A step change in heat flux and a rectangular pulse were applied to the heater. The effects of mass flux, heat flux (pulse amplitude), and pulse width on the heater temperature response and boiling dynamics were investigated in detail. Conditions at which onset of boiling occurred were identified and the repeatability of the boiling process was studied. Onset of boiling and the subsequent bubble dynamics was recorded with a high-speed video camera. Boiling initiated at very high wall superheat due to the smoothness of the heater surface and low surface tension of HFE-7000. At high heat fluxes, onset of boiling resulted in the formation of a vapor film on the surface and rapid heater temperature rise was observed. Time taken to initiate boiling decreased rapidly with increasing heat flux and then reached a constant value. The wall superheat at which boiling started increased with increasing heat flux and subsequently reached a constant limit.