Pulsating Heat Pipes: Basics of Functioning and Modeling

Nikolayev, Vadim; Marengo, Marco

doi:10.1142/9789813234406_0002

Cited by 19 publications

(15 citation statements)

References 84 publications

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“…Because of the non-stationary functioning that involves multiple vapor liquid interfaces, the 3D or even 2D direct numerical simulation are too costly; 1D modeling appears to be an only viable choice to make the parametric investigation. The simulation techniques has been recently reviewed in detail by Nikolayev and Marengo (2018). To our knowledge, the orientation effect has been studied by simulation only by Mameli et al (2012).…”

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confidence: 99%

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Pulsating Heat Pipe Simulations: Impact of PHP Orientation

Nekrashevych

Nikolayev

2019

Microgravity Sci. Technol.

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The pulsating (called also oscillating) heat pipe (PHP) is a simple capillary tube bent in meander and filled with a two-phase fluid. We discuss numerical simulations of the 10-turn copper-water PHP under vertical favorable (bottom-heated), vertical unfavorable (top-heated), and horizontal orientations. Within the present approach, the horizontal orientation is equivalent to the microgravity conditions. The simulations are performed with the in-house CASCO software. The time-averaged spatial distribution of the liquid plugs inside the PHP is influenced by gravity. This affects the overall PHP performance. We show that, independently of the PHP orientation, contribution of the latent heat transfer is large with respect to the sensible heat transfer. We discuss the phenomena occurring inside the PHP during startup and the stable regimes (intermittent and continuous oscillations followed by dryout).Nomenclature d tube inner diameter (m) F evaporator coverage fraction by a phase g gravity acceleration (m 2 /s) L length (m) P,Q power (W) R th heat transfer resistance (K/W) T temperature (

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confidence: 99%

“…To our knowledge, the orientation effect has been studied by simulation only by Mameli et al (2012). However their study used the code of Holley and Faghri (2005) who for some reason used an incorrect vapor energy equation (the initial approach of Shafii et al (2001) was entirely correct), see Nikolayev and Marengo (2018) for the discussion.…”

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confidence: 99%

Pulsating Heat Pipe Simulations: Impact of PHP Orientation

Nekrashevych

Nikolayev

2019

Microgravity Sci. Technol.

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“…less contact angle hysteresis, this capillary force in SRWF is 58% lower than water, see Table 3. In addition, numerical modelling shows that when the tube wall is heated, the fluid temperature is higher at the meniscus wedge (1) than at the meniscus center (2) due to the thinner liquid film [28]. In case of SRWF the surface tension will increase with the increasing temperature, so the temperature difference between the wedge and the center of the meniscus itself is responsible of a gradient of surface tension along the liquid/vapor interface.…”

Section: Discussion Of the Resultsmentioning

confidence: 99%

Experimental analysis of a Flat Plate Pulsating Heat Pipe with Self-ReWetting Fluids during a parabolic flight campaign

et al. 2018

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A Flat Plate Pulsating Heat Pipe (FPPHP) filled with an ordinary liquid (water) and a self-rewetting mixture (dilutes aqueous solutions of long-chain alcohols with unusual surface tension behaviour) is investigated under variable gravity conditions on board a 'Zero-g' plane during the 65 th Parabolic Flight Campaign of the European Space Agency. The FPPHP thermal performance in terms of evaporator and condenser temperatures, start-up levels and flow regimes is characterized for the two working fluids and a power input ranging from 0 to 200W (up to 17 W/cm 2 at the heater/evaporator wall interface). The experimental set-up also includes a transparent plate enabling the visualization of the oscillating flow patterns during the experiments. For a low power input (4 W/cm 2 ), the pulsating heat pipe filled with pure water is not able to work under low-g conditions, because the evaporator immediately exhibits dry-out conditions and the fluid oscillations stops, preventing heat transfer between the hot and cold side and resulting in a global increase of the temperatures. On the other hand, the FPPHP filled with the self-rewetting fluid runs also during the microgravity phase. The liquid rewets several times the evaporator zone triggering the oscillatory regime. The selfrewetting fluid helps both the start-up and the thermal performance of the FPPHP in microgravity conditions.

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“…One is interested in the force F = S ∆p exercised by the fluid on the walls. F can be obtained from the solution of the Navier-Stokes equations with the imposed oscillating pressure [18,30] as the tangential component of shear stress integrated over the wall area. Because of the phase shift mentioned above, the problem can be solved with the Fourier transform soF (the Fourier transform of F) is complex.…”

Section: Pressure Drop In the Liquid Plugsmentioning

confidence: 99%

“…In the past, the PHP functioning was reviewed by several authors [13][14][15][16][17][18] and in a book by Ma [19]. In this review we focus on the PHP hydrodynamic modeling that seems to be the only way to achieve a reliable PHP performance prediction for optimization of industrial prototypes.…”

Section: Introduction To the Php Predictive Modelingmentioning

confidence: 99%

Physical principles and state-of-the-art of modeling of the pulsating heat pipe: A review

Nikolayev

2021

Applied Thermal Engineering

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The Pulsating (called also oscillating) Heat Pipe (PHP) is a high performance passive heat transfer device. It consists in a closed capillary channel folded into several meanders, evacuated, and partially filled with a liquid and its vapor. One side is in thermal contact with a hot spot, the other with a cold spot. The oscillation of the liquid plugs and vapor bubbles spontaneously occurs after the heating beginning. The heat exchange takes place not only by latent heat transfer, but also by liquid convection. Both this advantage and the PHP structural simplicity make it competitive with respect to other kinds of heat pipes. However, the PHP operation is non-stationary and depends on many physical and material parameters. As a result, application of empirical correlations is quite unsuccessful. More sophisticated direct modeling is thus required. In this review, we present the past, present, and future perspectives of the theoretical PHP studies. The physical phenomena on the level of a single bubble and single liquid plug is addressed first. In this context, the modeling of the simplest, single branch PHP is described as a necessary first step toward the PHP understanding and model validation. The modeling of interaction between the bubbles and plugs (bubble generation and disappearance, plug evaporation) is discussed next. Finally, the state of the art of the physical modeling and simulation of the multi-turn PHP is reviewed and the difference between existing approaches is explained.

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Pulsating Heat Pipes: Basics of Functioning and Modeling

Cited by 19 publications

References 84 publications

Pulsating Heat Pipe Simulations: Impact of PHP Orientation

Pulsating Heat Pipe Simulations: Impact of PHP Orientation

Experimental analysis of a Flat Plate Pulsating Heat Pipe with Self-ReWetting Fluids during a parabolic flight campaign

Physical principles and state-of-the-art of modeling of the pulsating heat pipe: A review

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