Performance degradation of flattened heat pipes

Lin, Kuan-Ting; Wong, Shwin-Chung

doi:10.1016/j.applthermaleng.2012.06.001

Cited by 42 publications

(6 citation statements)

References 8 publications

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“…However, it is found that the thermal resistance only normal region agree well with experiments with STD of ±12.73%. Similar trend was also observed in (Lin and Wong, 2012) although the different parameters were employed. This can be importantly concluded that, there exists the specific value of the final thickness of flattening process.…”

Section: Effect Of Pipe Flattening On Overall Thermal Resistancesupporting

confidence: 79%

Flattening Effect on Heat Transfer Characteristics of a Sintered-Wick Heat Pipe

Intagun¹,

Terdtoon²,

Sakulchangsatjatai³

2013

American Journal of Applied Sciences

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The effect of pipe flattening on heat transfer characteristics and the internal phenomena of a sintered-wick heat pipe has been investigated by using three-dimensional Finite Element Method. The calculation domains were focused at three important regions, i.e., vapor core, wick and wall. The Cartesian coordinates and the three-dimensional tetrahedral elements were applied in this model. The selected total elements were 638,400 to ensure the accuracy. The original diameter and total length of heat pipe were 6 mm and 200 mm, respectively. The composite wick made from sintered copper powder and grooved copper pipe was applied with water as working fluid. The vapor flow was assumed to be laminar and incompressible. The predicted results from the program were validated with the experimental results conducted with all similar controlled parameters. It was found that the predicted wall temperature and thermal resistance agreed well with the experimental data with the standard deviations of Â±5.95 and Â±32.85%, respectively. Furthermore, the overall thermal resistances of the tubular heat pipes (original diameter of 6 mm), which were flattened into the final thickness of 4.0 and 3.0 mm, decreased from 0.91 to 0.83Â°C/W due to an increase of the contacted surface for heat transfer surface. However, the overall thermal resistance of a flattened heat pipe with the final thickness of 2.5 mm increased to 0.88Â°C/W, resulting from drastic increase of pressure drop in narrower vapor core. The pivotal final thickness of flattened heat pipe, which is the minimum thickness of pipe to be flattened, has been analysed to be 2.75 mm (about 45% from original diameter)

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Section: Effect Of Pipe Flattening On Overall Thermal Resistancesupporting

confidence: 79%

Flattening Effect on Heat Transfer Characteristics of a Sintered-Wick Heat Pipe

Intagun¹,

Terdtoon²,

Sakulchangsatjatai³

2013

American Journal of Applied Sciences

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“…The findings indicated that a reduction in the internal cavity results in a notable increase in the flow resistance of the liquid and vapor, accompanied by a corresponding decrease in the thermal performance. Lin and Wong [ 10 ] conducted an investigation into the causes of performance degradation in flattened heat pipes. The findings revealed that a liquid accumulation inside the condensation section was the primary factor leading to the deterioration in the performance of the powder-sintered heat pipe, while the main reason for the grooved heat pipe was the reduction in liquid supply to the evaporation section due to the vapor–liquid interfacial shear [ 11 , 12 ], which resulted in the tendency for the heat pipe to dry out.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study of a Composite Wick Structure for Ultra-Thin Flattened Heat Pipes

Zhou,

Yang,

et al. 2024

Micromachines

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As the thickness of an ultra-thin flattened heat pipe (UTHP) decreases, the fabrication difficulty increases exponentially, and the thermal performance deteriorates rapidly. In this study, three types of composite wicks were developed for UTHPs with a 0.6 mm thickness: copper foam and mesh wick (CFMW), two layers of different mesh wick (TDMW), and three layers of the same mesh wick (TSMW). The startup and steady-state performances of the UTHPs with liquid filling ratios of 60% to 120% were investigated. The findings indicated that the CFMW UTHP with a filling ratio of 100% exhibited the best startup performance, with the highest equilibrium temperature of 58.37 °C. The maximum heat transport capacities of the CFMW, TDMW, and TSMW UTHP samples were 9, 8, and 8.5 W, respectively, at their corresponding optimum filling ratios of 110%, 90%, and 100%. The CFMW UTHP exhibited the lowest evaporation and condensation thermal resistances of 0.151 and 0.189 K/W, respectively, which were 24.67% and 41.85% lower than those of the TSMW UTHP. CFMW can be used to improve the thermal performance of UTHPs. This study provides important guidelines for the structural design, fabrication technology, and performance improvement of high-performance UTHPs used in portable electronic devices.

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“…Further, the effects of fill ratio and heat pipe orientation on thermal performance were explored. Lin and Wong (2013) tested the performance of flattened heat pipes with different wick structures. The wicks used were sintered powder or grooved structures.…”

Section: Introductionmentioning

confidence: 99%