Verification of a Transient Loop Heat Pipe Model

Wrenn, Kimberly R.; Krein, S.; Hoang, Triem T.; Allen, R.

doi:10.4271/1999-01-2010

Cited by 15 publications

(19 citation statements)

References 2 publications

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“…Wrenn et al in 1999 developed a functional LHP model embedded in the SINDA analyzer [23]; the model was correlated with the experimental data and when used to predict temperatures for a satellite application. An elaborated nodal model for a CPL space experiment considering the operation under presence of vapor phase in the liquid channel of the evaporator has been presented in 2000 [24].…”

Section: Introductionmentioning

confidence: 99%

Mathematical model of a loop heat pipe with cylindrical evaporator and integrated reservoir

Vlassov

Riehl

2008

Applied Thermal Engineering

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Section: Introductionmentioning

confidence: 99%

Mathematical model of a loop heat pipe with cylindrical evaporator and integrated reservoir

Vlassov

Riehl

2008

Applied Thermal Engineering

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“…It is remarkable to note that there was no time lag between the calculated and experimental results after a new power was applied to the LHP. In earlier works, a time lag was consistently reported [11,14,16]. Figure 10 presents the calculated temperature distribution in the condenser at two different power settings: 10 W and 35 W. In this figure, the relaxation times were shown at a given power setting (solid lines).…”

Section: Resultsmentioning

confidence: 84%

“…In general, these difficulties are associated with 1) mass and heat transfer in a porous body with evaporation or nucleation, 2) twophase flow during condensation from vapor to liquid in the condenser, and 3) two-phase flow in the compensation chamber (CC), which plays an important role in distributing liquid in the LHP. A smaller number of numerical models for transient operation of LHPs have been developed [11][12][13][14][15][16][17][18]. The models reported in [11][12][13][14] were for general transient operation of LHPs, whereas the others focused on the analysis of a particular operation's characteristics, such as multiple evaporators and multiple condensers [15], temperature-oscillating behavior [16], the most demanding prestart situation [17], and role of the secondary wick [18].…”

mentioning

confidence: 99%

Transient Thermo-Fluid Modeling of Loop Heat Pipes and Experimental Validation

Nishikawara

Nagano

Kaya

2013

Journal of Thermophysics and Heat Transfer

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A transient mathematical model is developed to study the transient response and analyze the distribution of heat load in a loop heat pipe. The model is based on the one-dimensional and time-dependent conservation equations for heat and fluid flow. The momentum and energy conservation equations for each of the loop heat pipe components are solved. The model results are compared against the data obtained from two miniature loop heat pipes using polytetrafluoroethylene wicks, ethanol, and acetone as working fluids. The mathematical model satisfactorily predicts the dynamic behavior of the loop heat pipe unit. It is shown that the percentage of heat leak across the wick decreases and the ratio of latent heat increases with increasing heat load. Some temperature overshoots observed in the calculation results are not observed in the experimental data. When a new power is applied, no time lag is observed in the loop heat pipe response between the simulation and experimental results. Nomenclature A = cross section area, m 2 A s = surface area, m 2 C = heat capacity, J∕kg c = constant in Chisholm correlation c p = specific heat at constant pressure, J∕kg K D = diameter, m f = Darcy's friction coefficient G A B = thermal conductance between A and B, W∕K Gr = Grashof number g = gravity, m∕s 2 h = heat transfer coefficient, W∕m 2 K h lat = latent heat, J∕kg k = thermal conductivity, W∕m K L = length, m _ m = mass flow rate, kg∕s Nu = Nusselt number Pr = Prandtl number p = pressure, Pa _ Q A B = rate of heat transfer from A to B, W _ Q apply = heat load, W q = amount of heat transfer per volume, W∕m 3 Re = Reynolds number T = temperature,°C u = velocity, m∕s V = volume, m 3 X = ratio between vapor and liquid frictional pressure loss Greek β = coefficient of volume expansion, 1∕K ε = porosity ν = kinematic viscosity coefficient, m 2 ∕s ρ = density, kg∕m 3 τ w = wall shear stress, Pa Φ i = square root of ratio between the frictional pressure loss in single phase i and two-phase flow Subscript amb = ambient bay = bayonet tube cc = compensation chamber e = evaporator eff = effective fc = forced convection gr = groove hb = heater block int = interface l = liquid nc = natural convection sat = saturation sub = subcooled v = vapor 2f = two phase

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“…In the experimental implementation, there are some measurements of absolute pressure (Ku et al, 2001;Ogushi et al, 2003;Lee et al, 2004;Joung et al, 2010b,a;Singh et al, 2010), and more rarely some measurements of differential pressures (Wrenn et al, 1999;Ku et al, 2001). A few experimental studies in the literature provide direct observations of some parts of the LHP.…”

Section: Instrumentationmentioning

confidence: 99%

State-of-the-Art Experimental Studies on Loop Heat Pipes

Launay¹,

Vallée²

2011

Frontiers in Heat Pipes

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The present study provides a concise overview of the main feature evolution of Loop Heat Pipe (LHP) designs, in particular on the evaporator/compensation chamber, based on experimental studies published between 1998 and 2010. It presents a synthesis of results on LHP performances at steady-state, and observations related to the LHP dynamic behaviours, as start-up or oscillating behaviours. The objective of this review is to gather as much information from the LHP experimental studies so as to provide a database, and thus promote the development of tools for understanding and predicting the LHP behaviors. The review shows some omissions in the LHP description and in the results presentation that makes these data difficult to use for further studies. This review should promote some coordination for future experimental works on LHP.

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Verification of a Transient Loop Heat Pipe Model

Cited by 15 publications

References 2 publications

Mathematical model of a loop heat pipe with cylindrical evaporator and integrated reservoir

Mathematical model of a loop heat pipe with cylindrical evaporator and integrated reservoir

Transient Thermo-Fluid Modeling of Loop Heat Pipes and Experimental Validation

State-of-the-Art Experimental Studies on Loop Heat Pipes

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