Optimization of wick shape in a loop heat pipe for high heat transfer

Nishikawara, Masahito; Nagano, Hosei

doi:10.1016/j.ijheatmasstransfer.2016.09.027

Cited by 33 publications

(11 citation statements)

References 18 publications

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“…Lengthening the TPCL dispersed the heat flux, thereby lowering the contribution of the TPCL to the heat transport process. This result demonstrates the literature assertion (Nishikawara and Nagano, 2017b). Figure 8 shows the temperature contours in the x-y cross sections of the classical wick and wick 1 at z = paxi/2.…”

Section: Resultssupporting

confidence: 84%

“…The pressure loss predicted by the three-dimensional model is larger than that by one-dimensional model shown in Ref. (Nishikawara and Nagano, 2017b). The classical wick with negligible pressure loss (18 Pa) can be modeled as a simple two-dimensional problem.…”

Section: Resultsmentioning

confidence: 76%

“…The fluid properties were calculated using the Reference Fluid Thermodynamic and Transport Properties (REFPROP) program (Lemmon et al, 2013). Table 2 Calculation conditions of the present study (Chernysheva and Maydanik, 2012;Nishikawara and Nagano, 2017b;Nishikawara et al, 2018;Lemmon et al, 2013). Figure 6 displays (a) the streamlines, (b) velocity contours, and (c) pressure contours of the working liquid in the classical wick, along with (d) the temperature contours in the y-z cross-section at x = Levap/2 of the classical wick (d).…”

Section: Resultsmentioning

confidence: 99%

“…For this reason, the authors of ref. (Nishikawara and Nagano, 2017b) proposed a design method based on TPCL length alone. They found an optimum TPCL length that maximizes the evaporator heat-transfer coefficient.…”

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confidence: 99%

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Numerical exploration of optimal microgroove shape in loop-heat-pipe evaporator

Yamada

Nishikawara

Yanada

2020

JTST

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A loop heat pipe (LHP) is a heat transport device driven by capillary pressure in porous media and the vapor-liquid phase change of a working fluid. LHPs are widely used in the electronic cooling systems of spacecraft (Okamoto et al., 2016), insulated gate bipolar transistors (Dupont et al., 2013), laptops (Lin et al., 2013), and other thermal engineering applications. As shown in Fig. 1, an LHP consists of an evaporator, a condenser, a vapor line, a liquid line, and a compensation chamber (CC). Unlike conventional heat pipes, the wick is enclosed in the evaporator, enabling long transport lengths and large radiation areas. The operating characteristics and working mechanisms of LHPs are reviewed in Maydanik (2005), Ku (1999), and Launay et al. (2007). The wick shape as well as porous materials and capillary structures critically affects the evaporator performance, but the design of the wick shape is complicated, which is focused in this paper. Some papers have attempted enhancement of the evaporator heat-transfer coefficient by parametric studies with respect to the shape (e.g., contact surface area between casing and wick, groove number, groove width, groove pitch, groove cross-sectional shape, groove location (in a wick or casing) and wick thickness) with a cylindrical or flat evaporator (

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Section: Resultssupporting

confidence: 84%

Section: Resultsmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Numerical exploration of optimal microgroove shape in loop-heat-pipe evaporator

Yamada

Nishikawara

Yanada

2020

JTST

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“…The proposed method for optimization of wick shape is presented in Ref. [22]. In addition, a detailed heat-transfer simulation at the TPCL should be performed in the future.…”

Section: Calculation Domain and Boundary Conditionsmentioning

confidence: 99%

Numerical study on heat-transfer characteristics of loop heat pipe evaporator using three-dimensional pore network model

Nishikawara

Nagano

Prat

2017

Applied Thermal Engineering

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An important consideration while designing the shape of a capillary evaporator is the phase distribution in the wick. However, the distribution depends on the working fluids and porous materials. This study investigates the heat-transfer characteristics of a loop heat pipe (LHP) evaporator by using a threedimensional pore network model with a dispersed pore size wick. The simulation considers saturated and unsaturated wicks. A stainless steel (SS)-ammonia, polytetrafluoroethylene (PTFE)-ammonia, and copper-water LHP are simulated. The copper-water LHP has the highest transition heat flux to the unsaturated wick. When the optimum evaporator shape of the copper-water LHP is designed, it is reasonable to assume that the phase state is saturated. On the other hand, for the ammonia LHP design, the state is assumed to be unsaturated. Simulation results show the heat-transfer structure in the evaporator and indicate that the applied heat flux concentrates on the three-phase contact line (TPCL) within the case, wick, and grooves. An evaporator configuration with circumferential and axial grooves is simulated to investigate the effect of the TPCL length. Results indicate that the optimum shape can be realized by varying the TPCL length. The proposed method is expected to serve as a simple approach to design an evaporator. Please cite this article in press as: M. Nishikawara et al., Numerical study on heat-transfer characteristics of loop heat pipe evaporator using three-dimensional pore network model, Appl. Therm. Eng.

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Analysis of Miniature Loop Heat Pipe Under Varying Working Fluids and Wick Materials at Low Heat Inputs

Krishna¹,

Kumar²

2019

Lecture Notes in Mechanical Engineering

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Optimization of wick shape in a loop heat pipe for high heat transfer

Cited by 33 publications

References 18 publications

Numerical exploration of optimal microgroove shape in loop-heat-pipe evaporator

Numerical exploration of optimal microgroove shape in loop-heat-pipe evaporator

Numerical study on heat-transfer characteristics of loop heat pipe evaporator using three-dimensional pore network model

Analysis of Miniature Loop Heat Pipe Under Varying Working Fluids and Wick Materials at Low Heat Inputs

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