Space Qualification of High Capacity Grooved Heat Pipes

Dubois, M.; Mullender, Bernard; Oost, Stéphane Van; Druart, J.; Supper, W.; Titterton, D.

doi:10.4271/951551

Cited by 7 publications

(4 citation statements)

References 8 publications

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“…This configuration combines a high capillary pumping pressure with a low axial pressure drop in the liquid. 2,3 In addition, the retardation of the liquid flow due to the countercurrent vapor flow over the liquidvapor interface is minimized as compared to other axial groove designs. However, the radial thermal resistance to heat transfer of the reentrant groove geometry may be larger compared to rectangular, trapezoidal, or triangular groove designs due to an increase in the wall thickness of the heat pipe.…”

Section: Introductionmentioning

confidence: 96%

Fluid Flow in Axial Reentrant Grooves with Application to Heat Pipes

Thomas

Damle

2005

Journal of Thermophysics and Heat Transfer

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The fully developed laminar flow within a reentrant groove has been analyzed using a finite element model. A parametric analysis was carried out to determine the Poiseuille number Po = fRe, the dimensionless mean velocity v * , and the dimensionless volumetric flow rateV * as functions of the geometry of the reentrant groove (groove height 1.0 < -H * < -4.0, slot half-width 0.05 < -W * /2 < -0.9, and fillet radius 0.0 < -R * f < -1.0), and the liquid-vapor shear stress (0.0 < -− −τ * lv < -2.5). The case in which the meniscus recedes into the reentrant groove was examined and could be a result of evaporator dryout or insufficient liquid fill amount. The cross-sectional area of the liquid in the groove, A * l , the meniscus radius R * m , and the aforementioned flow variables were calculated as functions of the meniscus contact angle (0 < -φ < -40 deg) and the meniscus attachment point (0.0 < -H * l < -2.75). Finally, the results of the numerical model were used to determine the capillary limit of a low-temperature heat pipe with two different working fluids, water and ethanol, for a range of meniscus contact angles. Nomenclaturecenter of circular portion of reentrant groove to top of slot, m H l = vertical location of attachment point of meniscus to reentrant groove wall, m H l,s = vertical location of attachment point of meniscus to sinusoidal groove wall, m H s = height of sinusoidal groove, m H tr = height of trapezoidal groove, m H * = H/R H * l = H l /R h f g = heat of vaporization, J/kg K = thermal conductivity, W/(m · K) L a = adiabatic length, m L c = condenser length, m L e = evaporator length, m L eff = effective heat pipe length, L e /2 + L a + L c /2, m N g = number of grooves n = coordinate normal to the liquid-vapor interface n * = n/R P = wetted perimeter, m Po = Poiseuille number, f Re P * = P/R = pressure, N/m 2 Q cap = capillary limit heat transport, Ẇ Q g = heat transfer due to a single groove, Ẇ Q t = total heat transported, N gQ g , W q lv = heat flux at the liquid-vapor interface, W/m 2 q * lv = q lv /q R q = internal volumetric heat generation, W/m 3 R = radius of circular portion of reentrant groove, m Re = Reynolds number, ρv D h /µ R f = radius of fillet, m R m = radius of meniscus, m R v = radius of heat pipe vapor space, m R * fwidth of slot, m W l = width of liquid meniscus at attachment point to reentrant groove wall, m W l,s = width of liquid meniscus at attachment point to sinusoidal groove wall, m W s = width of sinusoidal groove, m W tr = width of trapezoidal groove, m W * = W/R W * l = W l /R x, y, z = Cartesian coordinate directions x f,0 , z f,0 = location of center point of circular fillet, m x t , z t = point of tangency of fillet and circular portion of reentrant groove, m x * , y * , z * = x/R, y/R, z/R x * f,0circular segment duct half-angle, rad 395 Downloaded by MONASH UNIVERSITY on February 3, 2015 | http://arc.aiaa.org | 396 THOMAS AND DAMLEβ = aspect ratio for rectangular and trapezoidal grooves, 2H r /W r or 2H tr /W tr γ = triangular groove half-angle, rad θ = trap...

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Section: Introductionmentioning

confidence: 96%

Fluid Flow in Axial Reentrant Grooves with Application to Heat Pipes

Thomas

Damle

2005

Journal of Thermophysics and Heat Transfer

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“…Heat pipe with axial "X"-shaped groove has been introduced as an attractive option for a wide variety of advanced electronic devices, such as in the spacecraft thermal control system and microelectronic cooling system, due to the high efficiency heat transfer capability, stable operation under microgravity conditions and the high degree of temperature uniformity [18][19][20]. As an optimum choice of high capacity heat pipe with axial grooves in the frame provided by the European Space Agency [21], heat pipe with axial "X"-shaped grooves combines a high capillary pumping pressure with a low axial pressure drop in the return liquid, whose cross-sectional structure is shown in Fig. 2.…”

Section: Introductionmentioning

confidence: 99%

Evaporative Heat Transfer Analysis of a Heat Pipe With Hybrid Axial Groove

Bai¹,

Lin

Peterson

2013

Journal of Heat Transfer

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Through the application of thin film evaporation theory and the fundamental operating principles of heat pipes, a hybrid axial groove has been developed that can greatly enhance the performance characteristics of conventional heat pipes. This hybrid axial groove is composed of a V-shaped channel connected with a circular channel through a very narrow longitudinal slot. During the operation, the V-shaped channel can provide high capillary pressure to drive the fluid flow and still maintain a large evaporative heat transfer coefficient. The large circular channel serves as the main path for the condensate return from the condenser to the evaporator and results in a very low flow resistance. The combination of a high evaporative heat transfer coefficient and a low flow resistance results in considerable enhancement in the heat transport capability of conventional heat pipes. In the present work, a detailed mathematical model for the evaporative heat transfer of a single groove has been established based on the conservation principles for mass, momentum and energy, and the modeling results quantitatively verify that this particular configuration has an enhanced evaporative heat transfer performance compared with that of conventional rectangular groove, due to the considerable reduction in the liquid film thickness and a corresponding increase in the evaporative heat transfer area in both the evaporating liquid film region and the meniscus region.

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“…Therefore, attention should be paid to whether the application of "Ω"-shaped grooves in flow boiling could enhance the heat transfer coefficient or not. What's more, heat pipe with axially "Ω"-shaped grooves has shown stable operation under microgravity conditions and non-sensitivity with gravity direction [25]. But as mass flux in flow boiling is much higher than that in heat pipe, the effect of gravity direction on flow boiling in "Ω"-shaped grooved tube is still unclear.…”

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confidence: 99%

Experimental study on heat transfer characteristics of R134a flow boiling in “Ω”-shaped grooved tube with different flow directions

Cheng

Chen

Yuan

et al. 2017

International Journal of Heat and Mass Transfer

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To study the heat transfer enhancement of flow boiling in "Ω"-shaped grooved tube, an experimental investigation with refrigerant R134a as working fluid was conducted. The experiments were performed at different flow directions with mass flux of 10-30kg/(m 2 •s) and heat flux of 3-10kW/m 2 , respectively. The effects of vapor quality, heat flux and mass flux in horizontal, upward and downward flow were compared and analyzed. The comparative study with smooth tube showed significant enhancement of 1.5-3.3 times on heat transfer coefficient in horizontal and upward flow. Contrary to smooth tube results, heat transfer coefficient of downward flow is much higher than horizontal flow. The comparative study between different flow directions showed that heat transfer coefficient decreased with increasing vapor quality in horizontal and downward flow, however in upward flow, it was almost constant. In horizontal and upward flow, heat flux showed a strong positive effect and the effect of mass flux was not very sensitive; however in downward flow, heat flux showed a negative effect and mass flux showed a stronger positive effect. It is concluded that the effect mechanism of gravity on heat transfer in "Ω"-shaped grooved tube is quite different from smooth tube and heat transfer enhancement caused by "Ω"-shaped grooves is not only because of the increase in inner surface area. What's more, heat transfer is dominated by nucleate boiling in horizontal and upward flow, while in downward flow, convective boiling comes to dominate.

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Space Qualification of High Capacity Grooved Heat Pipes

Cited by 7 publications

References 8 publications

Fluid Flow in Axial Reentrant Grooves with Application to Heat Pipes

Fluid Flow in Axial Reentrant Grooves with Application to Heat Pipes

Evaporative Heat Transfer Analysis of a Heat Pipe With Hybrid Axial Groove

Experimental study on heat transfer characteristics of R134a flow boiling in “Ω”-shaped grooved tube with different flow directions

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