التفاصيل البيبلوغرافية
| العنوان: |
Time-resolved characterization of microchannel flow boiling during transient heating: Part 1 – Dynamic response to a single heat flux pulse. |
| المؤلفون: |
Kingston, Todd A.1 (AUTHOR) kingston@purdue.edu, Weibel, Justin A.1 (AUTHOR) jaweibel@purdue.edu, Garimella, Suresh V.1 (AUTHOR) sureshg@purdue.edu |
| المصدر: |
International Journal of Heat & Mass Transfer. Jun2020, Vol. 154, pN.PAG-N.PAG. 1p. |
| مصطلحات موضوعية: |
*MICROCHANNEL flow, *HEAT pulses, *HEAT flux, *SINGLE-phase flow, *FLOW visualization, *CHANNEL flow, *HEAT flux measurement |
| مستخلص: |
• Microchannel flow boiling under transient heating conditions is studied experimentally. • High-frequency sensor measurements are synchronized to flow visualizations. • Heat flux is pulsed between 15, 75, and 150 kW/m2 using a thin film heater. • The dynamic response to a transient pulse is qualitatively similar to that of a spring-mass-damper system. • Heat flux pulses that induce/arrest boiling cause a temporary wall temperature over/under-shoot. Microchannel flow boiling is an attractive approach for the thermal management of high-heat-flux electronic devices that are often operated in transient modes. In Part 1 of this two-part study, the dynamic response of a heated 500 μm channel undergoing flow boiling of HFE-7100 is experimentally investigated for a single heat flux pulse. Three heat flux levels exhibiting highly contrasting flow behavior under constant heating conditions are used: a low heat flux corresponding to single-phase flow (15 kW/m2), an intermediate heat flux corresponding to continuous flow boiling (75 kW/m2), and a very high heat flux which exceeds critical heat flux and would cause dryout if applied continuously (150 kW/m2). Transient testing is conducted by pulsing between these three heat flux levels and varying the pulse duration. High-frequency measurements of heat flux, wall temperature, pressure drop, and mass flux are synchronized to high-speed flow visualizations to characterize the boiling dynamics during the pulses. At the onset of boiling, the dynamic response resembles that of an underdamped mass-spring-damper system subjected to a unit step input. During transitions between single-phase flow and time-periodic flow boiling, the wall temperature temporarily over/under-shoots the eventual steady operating temperature (e.g. , by up to 20 °C) thus demonstrating that transient performance can extend beyond the bounds of steady performance. It is shown that longer duration high-heat-flux pulses (up to ~50% longer in some cases) can be withstood when the fluid in the microchannel is initial boiling, relative to if it is initially in the single-phase flow regime, despite being at an initially higher heat flux and wall temperature prior to the pulse. [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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