Numerical simulation of transient operation of loop heat pipes

Kaya, Tarik; Pérez, Ramón Almela; Gregori, Carmen; Torres, Alejandro

doi:10.1016/j.applthermaleng.2007.06.037

Cited by 71 publications

(42 citation statements)

References 11 publications

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“…The works aiming at studying the whole LHP, e.g. [3][4][5] to name but a few, and the works focussing on one of the components, the condenser or more often the evaporator because evaporator is generally considered as the key component in this system, e.g. [6,7].…”

Section: Introductionmentioning

confidence: 99%

Three dimensional liquid and vapour distribution in the wick of capillary evaporators

Mottet

Coquard

Prat

2015

International Journal of Heat and Mass Transfer

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a b s t r a c tHeat and mass transfer with liquid-vapour phase change in a representative unit cell of a capillary evaporator is studied using a mixed pore network model. The model combines the computation of temperature and pressure fields in vapour and liquid pores according to mean field approaches with pore scale invasion rules depending on the capillary pressure thresholds associated with each local constriction between two pores. The metallic body through which heat is transferred to the porous wick is also taken into account in the simulations. After comparisons with a visualisation experiment, numerical simulations performed in three dimensional pore networks lead to the identification of three main regimes depending on the applied heat load. Compared with previous works using the so-called vapour pocket assumption, the 3D simulations reveal a regime where the phase distribution within the wick is fundamentally different. This regime is characterised by the coexistence of both the liquid and vapour phases underneath the casing within the wick. This regime is shown to correspond to the best evaporator performance.

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Section: Introductionmentioning

confidence: 99%

Three dimensional liquid and vapour distribution in the wick of capillary evaporators

Mottet

Coquard

Prat

2015

International Journal of Heat and Mass Transfer

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“…[4][5][6]. Models of different components of LHPs were established based on mass and energy balance [7][8][9][10]. Steady-state and transient performances were studied experimentally in refs.…”

Section: Introductionmentioning

confidence: 99%

Operation characteristics of AMS-02 loop heat pipe with bypass valve

Wang

Joseph

Luo

et al. 2011

Sci. China Technol. Sci.

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Loop heat pipes (LHPs) were designed for the alpha magnetic spectrometer (AMS-02) to dissipate heat from the cryocoolers. A bypass valve is applied to the LHP to keep the cryocooler temperature above its limit (−20°C) in cold environment. Extensive experiments were performed on operation characteristics of LHPs with the bypass valve for AMS-02 during thermal vacuum and thermal balance (TVTB) test. We found that the bypass valve can start up successfully in cold environment. With the bypass valve, the evaporator temperature is stable and can meet the requirement of the cryocooler. We analyzed three operating modes of the bypass valve. Set point temperature and regulation temperature shifts were observed and their relations with the bypass valve temperature were given. alpha magnetic spectrometer, loop heat pipe, bypass valve, operation characteristic Citation: Wang N H, Burger J, Luo F, et al. Operation characteristics of AMS-02 loop heat pipe with bypass valve.

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“…To address that problem, they proposed using an auxiliary startup heater placed either on the transition tube or on the evaporator flange. Kaya et al developed a numerical model to simulate the startup performance characteristics of an LHP for the second prestart situation, during which the vapor removal channels are filled with liquid and the compensation chamber is two phase [15]. A global loop model has been designed by using a lumped parameter code (SINDA/FLUINT) for the simulation of startup conditions in a propylene LHP [16].…”

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confidence: 99%

Heat Transfer Investigation in Evaporator of Loop Heat Pipe During Startup

Chernysheva

Maydanik

Ochterbeck

2008

Journal of Thermophysics and Heat Transfer

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The problem of startup heating for a cylindrical evaporator of a loop heat pipe when the evaporator is completely filled initially with liquid has been examined. A two-dimensional mathematical heat transfer model has been formulated for this problem, for which the system of differential heat conduction equations was solved numerically. Modeling of the heat transfer processes in a cylindrical evaporator was conducted for different thermal regimes. The effects of the evaporator geometrical parameters and the thermophysical properties of materials during the formation of the temperature field were investigated. The results are presented in the analysis of the main factors that influence the dynamics of the evaporator startup. Nomenclature a = thermal diffusivity, m 2 s 1 c = specific heat, J kg 1 K 1 E 1 = copper-copper (Cu-Cu) evaporator E 2 = stainless-steel-nickel (SS-Ni) evaporator g = gravitational acceleration, m s 2 h = thickness of liquid layer, m Q = heat load, W q = heat flux, W m 2 L q = length of heat-supply zone, m r = coordinate in radial direction d = diameter, m S q = area of applied heat load, m 2 T = temperature, C = time, s z = coordinate in the z direction = coefficient of volumetric expansion, K 1 = thickness, m " = porosity = thermal conductivity, W m 1 K 1 = dynamic viscosity, Pa s = kinematic viscosity, m 2 s 1 = density, kg m 3 Subscripts av = average cc = central core eb = evaporator body or wall ev = evaporator l = liquid max = maximum min = minimum p = parasitic w = wick 0 = initial

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Numerical simulation of transient operation of loop heat pipes

Cited by 71 publications

References 11 publications

Three dimensional liquid and vapour distribution in the wick of capillary evaporators

Three dimensional liquid and vapour distribution in the wick of capillary evaporators

Operation characteristics of AMS-02 loop heat pipe with bypass valve

Heat Transfer Investigation in Evaporator of Loop Heat Pipe During Startup

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