Experimental Demonstration of Heat Pipe Operation beyond the Capillary Limit during Brief Transient Heat Loads

Baraya, Kalind; Weibel, Justin A.; Garimella, Suresh V.

doi:10.1109/itherm.2019.8757345

Cited by 2 publications

(1 citation statement)

References 17 publications

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“…The power input is maintained at 10 W for approximately 10 s, after which it is reduced to 3 W. The occurrence of an inflection point in the evaporator temperature at the point of dryout, along with the plateau in the condenser profile, is attributed to a transition in the primary heat transfer pathway before and after dryout, as discussed further in Ref. [37]. Heat transfer before dryout is primarily due to phase change at the evaporator, while heat conduction in the wall is the primary heat transfer pathway after dryout.…”

Section: Transient Dryout In Response To a Power Pulse Exceeding The mentioning

confidence: 96%

Heat pipe dryout and temperature hysteresis in response to transient heat pulses exceeding the capillary limit

Baraya

Weibel

Garimella

2020

International Journal of Heat and Mass Transfer

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The balance between the capillary pressure provided by the wick in a heat pipe or vapor chamber and the flow resistance to liquid resupply at the evaporator determines the maximum heat load that can be sustained at steady state. This maximum heat load is termed as the capillary limit; operation at steady heat loads above the capillary limit will result in dryout at the evaporator wick. However, different user needs and device workloads can lead to highly transient heat loads in applications ranging from consumer electronic devices to server processors. In these instances, the operation of heat pipes must be assessed in response to brief transient heat loads which could be higher than the notional capillary limit that governs dryout at steady state. In the current study, experiments are performed to characterize the transient thermal response of a heat pipe subjected to heat input pulses of varying duration that exceed the capillary limit. Transient dryout events due to a wick pressure drop exceeding the maximum available capillary pressure can be detected from an analysis of the measured temperature signatures. It is demonstrated that under such transient heating conditions, a heat pipe can sustain heat loads higher than the steady-state capillary limit for brief periods of time without experiencing dryout. If the heating pulse is sufficiently long as to induce transient dryout, the heat pipe may experience an elevated steady-state temperature even after the heat load is reduced back to a level lower than the capillary limit. The steady-state heat load must then be reduced to a level much below the capillary limit to fully recover the original thermal resistance of the heat pipe. This characteristic temperature hysteresis following transient dryout has significant implications for the use of heat pipes for pulsed power dissipation. Further experiments are performed to bound the range of heat loads over which the temperature hysteresis is present following a transient dryout event.

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Section: Transient Dryout In Response To a Power Pulse Exceeding The mentioning

confidence: 96%

Heat pipe dryout and temperature hysteresis in response to transient heat pulses exceeding the capillary limit

Baraya

Weibel

Garimella

2020

International Journal of Heat and Mass Transfer

Self Cite

View full text Add to dashboard Cite

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Experimental investigation on the heat transfer performance of high-temperature potassium heat pipe for nuclear reactor

Tian

Xiao

Wang

et al. 2021

Nuclear Engineering and Design

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Experimental Demonstration of Heat Pipe Operation beyond the Capillary Limit during Brief Transient Heat Loads

Cited by 2 publications

References 17 publications

Heat pipe dryout and temperature hysteresis in response to transient heat pulses exceeding the capillary limit

Heat pipe dryout and temperature hysteresis in response to transient heat pulses exceeding the capillary limit

Experimental investigation on the heat transfer performance of high-temperature potassium heat pipe for nuclear reactor

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