Analysis of the operational characteristics and limits of a loop heat pipe with porous element in the condenser

Muraoka, Issamu; Ramos, Fernando M.; Vlassov, Valeri V.

doi:10.1016/s0017-9310(00)00259-3

Cited by 51 publications

(19 citation statements)

References 10 publications

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“…There are only a few works about the numerical investigations. Muraoka and his co-authors developed a mathematical model based on the nodal method and analyzed the operational limits and dry-out failure mechanisms (Muraoka et al, 2001;). Pouzet and his co-authors proposed a global model to study the fundamental response mechanisms subjected to various heat load transients (Pouzet et al, 2004).…”

Section: Fig 1 Cpl Function Schematicmentioning

confidence: 99%

“…Capillary Pumped Loop (CPL) is a two-phase heat-transport device, which rely on the surface-tension forces induced by a fine pore wick to drive a working fluid (Muraoka et al, 2001;Cao and Faghri, 1994;Kaya et al, 2008). These devices use the same basic principle of the widely known heat pipes, i.e., closed evaporation-condensation cycle being maintained by capillary pumping.…”

Section: Introductionmentioning

confidence: 99%

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Transient Modeling of CPL Based on Mesoscaled Analysis by Lattice Boltzmann Method

Xuan

Zhao

Li³

2010

Frontiers in Heat Pipes

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A transient model of a Capillary Pumped Loop (CPL) is proposed to predict the thermal and dynamic behavior, which includes two coupled modules: the thermal model and the hydrodynamic module. The thermal module is based on the nodal method and the dynamic module of the liquidvapor interface is based on the molecular kinetic theory. Especially, a thermal non-equilibrium model is proposed to predict the temperature of evaporator, which is unlike some traditional numerical method associate with the CPL system. In the present model, vapor is treated as a compressible phase, so an equation of state (EOS) should be used to complete the controlling equations. A mesoscaled multiphase lattice Boltzmann model (LBM) is proposed to analyze the different working fluids, which can help us to choose appropriate EOS. Combining these two models for different scale, the behavior of ammonia is analyzed by the LBM. The processes such as the start-up, the temperature oscillations in the reservoir and the heat load change in the evaporator are investigated by the transient model of a whole CPL. The numerical results of the LBM show that the PengRobinson (P-R) equation is more appropriate for the ammonia and the results of the macroscopic transient model show that why the start-up of a CPL becomes a failure easily and temperature oscillations in the reservoir are disadvantageous to the operation of CPL. With this new mixed algorithm, the mesoscaled behavior of the working fluid and the operation mechanism of a whole CPL can be investigated in detail, which can provide guidance for the design of a CPL system.

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Section: Fig 1 Cpl Function Schematicmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transient Modeling of CPL Based on Mesoscaled Analysis by Lattice Boltzmann Method

Xuan

Zhao

Li³

2010

Frontiers in Heat Pipes

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“…For example, Kim and Peterson developed a reversible LHP with a condenser wick, but the wick was integrated as an alternate evaporator wick in the reverse operation [15]. Another study by Muraoka et al reported flooded condenser wicks, with a liquid film on the wick surface [16]. To remove the liquid film and form a capillary meniscus at the wick surface, the heat pipe needs to operate with the appropriate liquid and vapor pressures.…”

Section: Introductionmentioning

confidence: 99%

Development and Characterization of an Air-Cooled Loop Heat Pipe With a Wick in the Condenser

Kariya¹,

Peters²,

Cleary³

et al. 2013

Journal of Thermal Science and Engineering Applications

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Thermal management of modern electronics is rapidly becoming a critical bottleneck of their computational performance. Air-cooled heat sinks offer ease and flexibility in installation and are currently the most widely used solution for cooling electronics. We report the characterization of a novel loop heat pipe (LHP) with a wick in the condenser, developed for the integration into an air-cooled heat sink. The evaporator and condenser are planar (102 mm Â 102 mm footprint) and allow for potential integration of multiple, stacked condensers. The condenser wick is used to separate the liquid and vapor phases during condensation by capillary menisci and enables the use of multiple condensers with equal condensation behavior and performance. In this paper, the thermal-fluidic cycle is outlined, and the requirements to generate capillary pressure in the condenser are discussed. The LHP design to fulfill the requirements is then described, and the experimental characterization of a single-condenser version of the LHP is reported. The thermal performance was dependent on the fan speed and the volume of the working fluid; a thermal resistance of 0.177 C/W was demonstrated at a heat load of 200 W, fan speed of 5000 rpm and fluid volume of 67 mL. When the LHP was filled with the working fluid to the proper volume, capillary pressure in the condenser was confirmed for all heat loads tested, with a maximum of 3.5 kPa at 200 W. When overfilled with the working fluid, the condenser was flooded with liquid, preventing the formation of capillary pressure and significantly increasing the LHP thermal resistance. This study provides the detailed thermal-fluidic considerations needed to generate capillary pressure in the condenser for controlling the condensation behavior and serves as the basis of developing multiplecondenser LHPs with low thermal resistance.

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“…Various configurations and features of LHPs are well described in the literature [1][2][3][4][5][6][7][8][9][10]. Owing to its prominent advantages over conventional heat pipes, LHP has the potential to be used widely as efficient cooling devices for high-power electronic components in the near future.…”

Section: Introductionmentioning

confidence: 99%

“…Maidanik and Fershtater [1,2] suggested employing an auxiliary heater as an active temperature control device of the compensation chamber to maintain the temperature of LHP quasi-stable against a certain range of heat-load variation. Muraoka et al [3] investigated bubble formation in the liquid core and its effect on the dry-out failure, using a specific LHP having a porous element in the condenser, and suggested conditions to predict the dry-out. Mo et al [4,5] employed an electro-hydrodynamic technique to induce an additional pressure difference in an effort to reduce the start-up time and thus to enhance the thermal performance of LHP.…”

Section: Introductionmentioning

confidence: 99%

Bypass line assisted start-up of a loop heat pipe with a flat evaporator

Boo

Jung

2009

J Mech Sci Technol

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Loop heat pipes often experience start-up problems especially under low thermal loads. A bypass line was installed between the evaporator and the liquid reservoir to alleviate the difficulties associated with start-up of a loop heat pipe with flat evaporator. The evaporator and condenser had dimensions of 40 mm (W) by 50 mm (L). The wall and tube materials were stainless steel and the working fluid was methanol. Axial grooves were provided in the flat evaporator to serve as vapor passages. The inner diameters of liquid and vapor transport lines were 2 mm and 4 mm, respectively, and the length of the two lines was 0.5 m each. The thermal load range was up to 130 W for horizontal alignment with the condenser temperature of 10˚C. The experimental results showed that the minimum thermal load for start-up was lowered by 37% when the bypass line was employed.

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Analysis of the operational characteristics and limits of a loop heat pipe with porous element in the condenser

Cited by 51 publications

References 10 publications

Transient Modeling of CPL Based on Mesoscaled Analysis by Lattice Boltzmann Method

Transient Modeling of CPL Based on Mesoscaled Analysis by Lattice Boltzmann Method

Development and Characterization of an Air-Cooled Loop Heat Pipe With a Wick in the Condenser

Bypass line assisted start-up of a loop heat pipe with a flat evaporator

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