Experimental study of the flat plate pulsating heat pipe operation during dry-out and flow re-activation periods under microgravity conditions

Slobodeniuk, Maksym; Bertossi, Rémi; Ayel, Vincent; Ravichandran, Rajalakshmi; Thyagarajan, Karthik; Romestant, Cyril; Bertin, Yves

doi:10.1016/j.ijmultiphaseflow.2021.103888

Cited by 18 publications

(3 citation statements)

References 28 publications

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“…At present, some studies show that pulsating flow in microchannels can enhance heat transfer [53][54][55]. The results of pulsating flow showed that forced pulsations could enhance average heat transfer.…”

Section: Pulsating Flow In a Microchannelmentioning

confidence: 99%

Microchannel Gas Flow in the Multi-Flow Regime Based on the Lattice Boltzmann Method

Li,

Ning,

Lü

2024

Entropy

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In this work, a lattice Boltzmann method (LBM) for studying microchannel gas flow is developed in the multi-flow regime. In the LBM, by comparing previous studies’ results on effective viscosity in multi-flow regimes, the values of the rarefaction factor applicable to multi-flow regions were determined, and the relationship between relaxation time and Kn number with the rarefaction factor is given. The Kn number is introduced into the second-order slip boundary condition together with the combined bounce-back/specular-reflection (CBBSR) scheme to capture the gas flow in the multi-flow regime. Sensitivity analysis of the dimensionless flow rate to adjustable parameters using the Taguchi method was carried out, and the values of adjustable parameters were determined based on the results of the sensitivity analysis. The results show that the dimensionless flow rate is more sensitive to j than h. Numerical simulations of Poiseuille flow and pulsating flow in a microchannel with second-order slip boundary conditions are carried out to validate the method. The results show that the velocity profile and dimensionless flow rate simulated by the present numerical simulation method in this work are found in the multi-flow regime, and the phenomenon of annular velocity profile in the microchannel is reflected in the phases.

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Section: Pulsating Flow In a Microchannelmentioning

confidence: 99%

Microchannel Gas Flow in the Multi-Flow Regime Based on the Lattice Boltzmann Method

Li,

Ning,

Lü

2024

Entropy

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“…The dynamic stiffnesses of the Y-axis and Z-axis are not more than 0.2 N/mm, which is smaller than the graphite. Slobodeniuk et al [91] designed a PHP composed of molybdenum and sapphire cover plate for the parabolic flight activities. Based on the We number and Ga number as defined in Equation ( 8), PHP was evaluated by the average We number obtained was the same as the reference critical value (We crit = 4) and the Ga number (1980) was much higher than the reference critical value (Ga crit = 160).…”

Section: Extensive Application and Promotionmentioning

confidence: 99%

Micro-Channel Oscillating Heat Pipe Energy Conversion Approach of Battery Heat Dissipation Improvement: A Review

Xin

Zhu

2022

Energies

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The application of batteries has become more and more extensive, and the heat dissipation problem cannot be ignored. Oscillating Heat Pipe (OHP) is a good means of heat dissipation. In this paper, the methods to improve the energy conversion and flow thermal performance of micro-channel OHP are studied and summarized. The working principle, heat transfer mechanism, advantages and applications of PHP are also introduced in detail in this study. Proper adjustment of the micro-channel layout can increase the heat transfer limit of PHP by 44%. The thermal resistance of two-diameter channel PHP is 45% lower than that of conventional PHP. The thermal resistance of PHP under uneven heating can be reduced to 50% of the original. PHP pulse heating can alleviate the phenomenon of dryness. Different working fluids have different effects on PHP. The use of graphene nano-fluids as the work medium can reduce the thermal resistance of PHP by 83.6%. The work medium obtained by the mixture of different fluids has the potential to compensate for the defects while inheriting the advantages of a single fluid.

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“…Due to the manufacturing complexity of inserting pressure probes inside the fluid stream, the fluid-dynamic behavior of FPPHPs is commonly studied by means of direct fluid visualizations. Slobodeniuk et al [17] investigated stopovers of a seven-turn FPPHP under micro-gravity conditions through high-speed visualization. By means of a liquid-vapor interfaces tracking technique, previously introduced by Pietrasanta et al [18], the menisci displacement was assessed and both fluid velocity and fluid acceleration were evaluated.…”

Section: Introductionmentioning

confidence: 99%

Thermographic Investigation on Fluid Oscillations and Transverse Interactions in a Fully Metallic Flat-Plate Pulsating Heat Pipe

et al. 2023

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The present investigation deals with the quantification of fluid oscillation frequencies in a metallic pulsating heat pipe tested at varying heat loads and orientations. The aim is to design a robust technique for the study of the inner fluid dynamics without adopting typical experimental solutions, such as direct fluid visualizations through transparent inserts. The studied device is made of copper, and it is partially filled with a water–ethanol mixture (20 wt.% of ethanol). Heat fluxes locally exchanged between the working fluid and the device walls are first assessed through the inverse heat conduction problem resolution approach by processing outer wall temperature distributions acquired by thermography. The estimated local heat transfer quantities are therefore processed to quantify the fluid oscillatory behavior in every device branch during the intermittent flow and full activation regimes, thus providing a deeper insight into the heat transfer modes. After dealing with a further validation of the inverse approach in terms of oscillation frequency restoration capability, the wall-to-fluid heat fluxes referred to each channel are processed by means of the wavelet method. Scalograms and power spectra of the considered signals are presented for a time-based analysis of the working fluid oscillations, as well as for the identification of dominant oscillation frequencies. Fluid motion is then quantified in terms of the continuity of fluid oscillations and activity of channels by applying a scalogram denoising technique named K-means clustering method. Moreover, a statistical reduction of the channel-wise dominant oscillation frequencies is performed to provide useful references for the interpretation of the overall oscillatory behavior. The link between oscillations and transverse interactions is finally investigated. The vertical bottom-heated mode exhibits stronger fluid oscillations with respect to the horizontal mode, with fluid oscillation frequencies ranging from 0.78 up to 1 Hz. Nonetheless, the fluid motion is more stable in terms of oscillation frequency between channels when the device operates in the horizontal orientation probably due to negligible buoyancy effects. Moreover, thermal interactions between adjacent channels are found to be stronger when the oscillatory behavior presents similar features from channel to channel in horizontal orientation. The proposed method for fluid oscillation analyses in fully metallic flat-plate pulsating heat pipes can be effectively adopted to other flat-plate layouts without any need for transparent windows, thus reducing the overall complexity of experimental set-ups and providing, at the same time, a good insight into the inner fluid dynamics.

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Experimental study of the flat plate pulsating heat pipe operation during dry-out and flow re-activation periods under microgravity conditions

Cited by 18 publications

References 28 publications

Microchannel Gas Flow in the Multi-Flow Regime Based on the Lattice Boltzmann Method

Microchannel Gas Flow in the Multi-Flow Regime Based on the Lattice Boltzmann Method

Micro-Channel Oscillating Heat Pipe Energy Conversion Approach of Battery Heat Dissipation Improvement: A Review

Thermographic Investigation on Fluid Oscillations and Transverse Interactions in a Fully Metallic Flat-Plate Pulsating Heat Pipe

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