Variation in oscillating heat pipe performance

Stevens, Kimberly A.; Smith, Sally M.; Taft, Brenton

doi:10.1016/j.applthermaleng.2018.12.113

Cited by 19 publications

(6 citation statements)

References 21 publications

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“…Since start-up by linear instability requires a phase interface in a zone with a wall temperature gradient, the start-up probability is higher with more phase interfaces. This argument stands in agreement with Stevens et al (2019), who performed an extensive investigation on reproducibility of PHP start-up and operation and found that there may be significant differences in start-up reliability between two identically built PHPs.…”

Section: Influence Of the Filling Ratiosupporting

confidence: 89%

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Low-Order Model of the Dynamics and Start-Up of a Pulsating Heat Pipe

Schily¹,

Polifke²

2021

Frontiers in Heat and Mass Transfer

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A simple open-loop pulsating heat pipe model is proposed, which allows to analytically determine the start-up behavior by a linear stability analysis. Two distinct types of instability can occur in such a pulsating heat pipe: oscillatory and non-oscillatory. This paper demonstrates that for bubbles consisting of non-condensible gas, large temperature gradients along the wall are required to achieve start-up, whereas start-up is fairly easy to achieve when there is only a single working medium that forms bubbles from its vapor. The study also finds that surface tension as such only influences start-up indirectly, while contact angle hysteresis dampens out any instabilities.

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Section: Influence Of the Filling Ratiosupporting

confidence: 89%

“…More recently, performance improvements were achieved by deviating from the classical structure of a PHP and introducing e.g. multiple branches or cross-talk between sections (Fairley et al, 2015;Shi et al, 2011;Stevens et al, 2019). Also related are wire-bonded micro heat pipes (Sobhan and Peterson, 2019).…”

Section: Introductionmentioning

confidence: 99%

Low-Order Model of the Dynamics and Start-Up of a Pulsating Heat Pipe

Schily¹,

Polifke²

2021

Frontiers in Heat and Mass Transfer

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“…The stronger surface tension forces helped the two-phase flow and formed natural separation of liquid slugs and vapor plugs during operation [24]. Bastakoti et al [66] suggested that if r h ≥ r hmax , the effect of the surface tension is reduced and the working fluid will be stratified by gravity and oscillatory motion will cease.…”

Section: Resultsmentioning

confidence: 99%

“…This flat-plate heat pipe is known as closed-loop flat-plate oscillating heat pipe (CL-FPOHP). The CL-FPOHPs differ significantly from traditional heat pipes in that they do not require a wick structure to move the condensed working fluid back to the evaporator section [24][25][26][27][28]. An oscillating heat pipe invented by Akachi [29] has been suggested in various electronics systems because of its high heat transfer capacity.…”

Section: Introductionmentioning

confidence: 99%

Influence of the channel profile on the thermal resistance of closed-loop flat-plate oscillating heat pipe

Mehta

Mehta²,

Patel

2020

J Braz. Soc. Mech. Sci. Eng.

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The closed-loop flat-plate oscillating heat pipe (CL-FPOHP) is a new two-phase heat transfer device for an effective thermal management in different systems. A number of theoretical and experimental investigations have been carried out on the CL-FPOHP in the past decades after its invention. However, due to the operational mechanism of the CL-FPOHP, the effects of channel profile on the thermal resistance have not been completely revealed so far. This paper aims at discussing the thermal resistance and thermal conductivity by changing the shape and size of the CL-FPOHPs channel. The thermal resistances of the CL-FPOHPs were investigated by varying the channel shape from square to circular, channel sizes from 2 × 2 mm 2 to 5 × 5 mm 2 , and heat load from 10 to 120 W. The pure copper was used to develop the CL-FPOHP and charged with the acetone with a charge ratio of 70%. The most suitable channel shape for the CL-FPOHP was found to be a square channel, and the most suitable channel size was observed to be 2 × 2 mm 2. The highest thermal conductivity of the CL-FPOHP reached to 2137 W/m °C. Keywords Flat-plate oscillating heat pipe • Two-phase heat transfer • Thermal resistance • Channel profile List of symbols Bo Bond number, g(l − v) r h 2 g Gravitational force (m/s 2) l Liquid density (kg/m 3) Subscripts CL-FPOHP Closed-loop flat-plate oscillating heat pipe FPOHP Flat-plate oscillating heat pipe TOHP Tubular oscillating heat pipe e Evaporator c Condenser l Liquid v Vapor W Watt L Distance of the two centers of the evaporator and condenser A Total cross-sectional area of CL-FPOHP

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“…OHPs charged with fluids with higher latent heat (e.g., water) may have better heat transfer performance in terms of maximum heat flux, but the start-up power is higher. The influence of operational parameters on the heat transfer was investigated by some researchers, such as Stevens et al [16]. Operational parameters, which include a filling ratio (FR), inclination angle and heat load, etc., have significant effects on the heat transfer.…”

Section: Introductionmentioning

confidence: 99%

Heat Transport Capacity of an Axial-Rotating Single-Loop Oscillating Heat Pipe for Abrasive-Milling Tools

Qian

Marengo

et al. 2020

Energies

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In order to enhance heat transfer in the abrasive-milling processes to reduce thermal damage, the concept of employing oscillating heat pipes (OHPs) in an abrasive-milling tool is proposed. A single-loop OHP (SLOHP) is positioned on the plane parallel to the rotational axis of the tool. In this case, centrifugal accelerations do not segregate the fluid between the evaporator and condenser. The experimental investigation is conducted to study the effects of centrifugal acceleration (0–738 m/s2), heat flux (9100–31,850 W/m2) and working fluids (methanol, acetone and water) on the thermal performance. Results show that the centrifugal acceleration has a positive influence on the thermal performance of the axial-rotating SLOHP when filled with acetone or methanol. As for water, with the increase of centrifugal acceleration, the heat transfer performance first increases and then decreases. The thermal performance enhances for higher heat flux rises for all the fluids. The flow inside the axial-rotating SLOHP is analyzed by a slow-motion visualization supported by the theoretical analysis. Based on the theoretical analysis, the rotation will increase the resistance for the vapor to penetrate through the liquid slugs to form an annular flow, which is verified by the visualization.

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Variation in oscillating heat pipe performance

Cited by 19 publications

References 21 publications

Low-Order Model of the Dynamics and Start-Up of a Pulsating Heat Pipe

Low-Order Model of the Dynamics and Start-Up of a Pulsating Heat Pipe

Influence of the channel profile on the thermal resistance of closed-loop flat-plate oscillating heat pipe

Heat Transport Capacity of an Axial-Rotating Single-Loop Oscillating Heat Pipe for Abrasive-Milling Tools

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