Model-Based Method of Theoretical Design Analysis of a Loop Heat Pipe

Furukawa, Masao

doi:10.2514/1.14675

Cited by 23 publications

(13 citation statements)

References 16 publications

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“…Ku [10] and Furukawa [22] developed simplest LHP heat leak model that utilizes conductance parameter which varies with geometry and operating conditions.…”

Section: Loop Heat Pipementioning

confidence: 99%

“…Generally, this phenomenon occurs on the start of heat pipe operation at a low vapor pressure of the working fluid. Assuming that the vapor of the working fluid is the ideal gas and the vapor flow at the sound velocity throughout the heat pipe cross section is uniform, the sonic limit is determined by the relationship (22). The sonic limit does not depend on the heat pipe orientation and type of the heat pipe, and the same formula is applied for the gravity and wick heat pipe.…”

Section: Sonic Limitationmentioning

confidence: 99%

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Porous Structures in Heat Pipes

Němec¹

2018

Porosity - Process, Technologies and Applications

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This work deals with heat pipes with porous wick structures and experiments depending on the wick structure porosity, because the porosity is one of the wick structure properties which has effect on the heat transport ability of the heat pipe. The work describes manufacturing porous wick structures for wick heat pipe by sintering of copper metal powders with various powder grain size; manufacturing porous wick structures for loop heat pipe by sintering of copper and nickel metal powders with various powder grain size; influence of manufacturing technology on the wick structure porosity by microscopic analysis of the porous structure; design and construction of wick heat pipe and loop heat pipes; experimental determination influence of the wick structure porosity on the heat transport ability of loop heat pipes at various conditions; and experimental and mathematical determination influence of the wick structure porosity on the heat transport ability of wick heat pipes at various conditions.

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“…Ku [10] and Furukawa [22] developed simplest LHP heat leak model that utilizes conductance parameter which varies with geometry and operating conditions.…”

Section: Loop Heat Pipementioning

confidence: 99%

Section: Sonic Limitationmentioning

confidence: 99%

Porous Structures in Heat Pipes

Němec¹

2018

Porosity - Process, Technologies and Applications

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“…If the mass flow rate is estimated by [30,31] _ m Q evap =h fg (42) the global energy balance sharply increases upon hard-filling of the reservoir. Figure 7 compares the predicted LHP temperatures, using Eqs.…”

Section: E Numerical Errors and Experimental Validationmentioning

confidence: 99%

Thermohydraulic Modeling of Capillary Pumped Loop and Loop Heat Pipe

Adoni¹,

Ambirajan²,

Jasvanth³

et al. 2007

Journal of Thermophysics and Heat Transfer

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Capillary pumped loop (CPL) and loop heat pipe (LHP) are passive heat transport devices that are gaining importance as a part of the thermal control system of modern high power spacecraft. A mathematical model to simulate the thermohydraulic performance of CPLs and LHPs is required for the design of such a thermal control system. In this study a unified mathematical model to estimate thermal and hydraulic performance of a CPL and an LHP with a two-phase or a hard-filled reservoir is presented. The steady-state model is based on conservation of energy and mass in the system. Heat exchange between the loop and the surroundings and pressure drops in the loop are calculated. This study presents the results of numerical studies on a CPL and an LHP. The constant conductance regime in a CPL or an LHP occurs when the reservoir is hard-filled. It also occurs in an LHP if the condenser is fully used. The heat leak across the wick becomes significant in a hard-filled LHP because the core is no longer saturated and hence the mass flow rate must be calculated using an energy balance on the outer surface of the wick. Nomenclatureenergy imbalance in the evaporator core and CC, W f = Darcy friction factor G = mass velocity, kg m 2 s 1 H = heat transfer coefficient, W m 2 K 1 h = enthalpy, J kg 1 K = wick permeability, m 2 k = thermal conductivity, W m 1 K 1 L = length, m L cond = length of condenser, m L condensation = length of condensation, m L evap-rt = distance between points 7 and 4, m L rt-hydr = vertical distance between loop and the reservoir, m L step = refers to step size in RKM, m M = mass of working fluid, kg _ m = mass flow rate, kg s 1 P = pressure, Pa Q = heat, W Q deprime = heat load at which CPL deprimes for limited condenser length, W Q hf = heat load at which reservoir is hard-filled, W Q open = heat load at which condenser fully opens, W r = radius, m T = temperature, K t = thickness, m U = overall heat transfer coefficient, W m 2 K 1 u = velocity, m s 1 V = volume, m 3 x = dryness fraction of vapor z = length, m v = void fraction, A v =A = volume fraction of liquid in the reservoir = perimeter, m = porosity " = numerical error (convergence criterion) # = normalized energy imbalance = conductance, W K 1 = density, kg m 3 = surface tension, N m 1 = two-phase friction multiplier Subscripts acc = acceleration c = core cond = condenser cond 0 = refers to region where condensation is occurring e = effective evap = evaporator ex = exchange f = friction fg = difference in thermodynamic property in liquid and vapor phase g = groove i = inner part of tube ins = insulation L = leak l = liquid ll = liquid line lo = liquid only load = refers to heat load applied externally loop = part of the system excluding the reservoir o = outer part of tube P = pressure r = reservoir/radial res = reservoir sc = subcooler sink = sink of condenser t = tube/evaporator teeth tp = two-phase v = vapor/(volume in case of specific heat) vl = vapor line vo = vapor only w = wick wp = wick pore ws = particle diameter in sintering z = length dir...

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“…Such models have demonstrated great utility in shedding light on the internal physical behavior of LHPs; however, they do not comprehensively describe the heat-transfer performance of the entire system. Individual models for predicting the steady-state performance of LHP components-evaporator, vapor line, condenser, and liquid line-have previously been proposed by Furukawa [21], Abhijit et al [22], Launay et al [23], and Bai et al [24]. These models, in combination, facilitate prediction of the effect of LHP-system design variables on heat-transfer performance.…”

Section: Introductionmentioning

confidence: 99%

A Novel Analytical Modeling of a Loop Heat Pipe Employing the Thin-Film Theory: Part I—Modeling and Simulation

Jung

Boo

2019

Energies

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In this study, steady-state analytical modeling of a loop heat pipe (LHP) equipped with a flat evaporator is presented to predict the temperatures and pressures at each important part of the LHP—evaporator, liquid reservoir (compensation chamber), vapor-transport tube, liquid-transport tube, and condenser. Additionally, this study primarily focuses on analysis of the evaporator—the only LHP component comprising a capillary structure. The liquid thin-film theory is considered to determine pressure and temperature values concerning the region adjacent to the liquid-vapor interface within the evaporator. The condensation-interface temperature is subsequently evaluated using the modified kinetic theory of gases. The present study introduces a novel method to estimate the liquid temperature at the condensation interface. Existence of relative freedom is assumed with regard to the condenser configuration, which is characterized by a simplified liquid–vapor interface. The results obtained in this study demonstrate the effectiveness of the proposed steady-state analytical model with regard to the effect of design variables on LHP heat-transfer performance. To this end, the condenser length, porosity of its capillary structure, and drop in vapor temperature therein are considered as design variables. Overall, the LHP thermal performance is observed to be reasonably responsive to changes in design parameters.

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Model-Based Method of Theoretical Design Analysis of a Loop Heat Pipe

Cited by 23 publications

References 16 publications

Porous Structures in Heat Pipes

Porous Structures in Heat Pipes

Thermohydraulic Modeling of Capillary Pumped Loop and Loop Heat Pipe

A Novel Analytical Modeling of a Loop Heat Pipe Employing the Thin-Film Theory: Part I—Modeling and Simulation

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