Compatibility and reliability of heat pipe materials

Basiulis, A.; Prager, R. C.

doi:10.2514/6.1975-660

Cited by 15 publications

(14 citation statements)

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“…[18] High surface tension helps also to wet the wick and the wall. [26] The performance of a heat pipe or a vapor chamber is greatly reduced if the working fluid cannot flow freely inside the wick. As a result, a low viscosity liquid is preferred.…”

Section: Methodsmentioning

confidence: 99%

“…These forces vary with temperature and pressure, but changes are very small compared to the other forces in the system. [26] The thermal conductivity of the working fluid has to be as high as possible. This helps to carry heat from the wall and the wick evenly into the working fluid.…”

Section: Methodsmentioning

confidence: 99%

“…It can help to minimize the risk of localized boiling at the interface between the wick and the wall. [26] In order to have a good capillary force, the working fluid has to wet the wick and the wall completely. If the continuous fluid film is broken, then the flow will be disturbed and might lead to dry out.…”

Section: Methodsmentioning

confidence: 99%

“…Low viscosity also lowers the pressure drop in the wick. [26,28] During vaporization, energy is needed to turn liquid into vapor. The energy is held by the vapor until it is turned back to liquid.…”

Section: Methodsmentioning

confidence: 99%

“…It is easy to see that there is a very wide range of working fluids to suit different operating temperatures. [26] The working fluid has to be selected well to maximize the heat transfer. As mentioned earlier, the working fluid handles the most significant portion of the heat transfer in a heat pipe and a vapor chamber.…”

Section: Methodsmentioning

confidence: 99%

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Flexible CFD simulation model of a thin vapor chamber for mobile applications

Niittymaki¹,

Biber

Carbone

2016

2016 22nd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)

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Heat loads produced by electronics inside a mobile device are increasing as more computing power is packed into them. During the design phase of a product, these loads have to be taken into account. Simulations provides a way to try different designs more quickly, and built-in optimization tools help to find the most suitable solution.Vapor chambers are thin heat spreaders that offer very high spreading capabilities without adding too much thickness to a low profile device. They work by evaporating water to steam, which transfers heat away from a heat source to the cooler regions of the chamber. This means that to simulate a vapor chamber correctly it would require simulating phase changes and rapid mass flows in very thin volume. This would consume a lot of computing time, which makes it unusable in detailed simulation in the system level models. Therefore, a simpler model has to be developed. A few of these exist, but they were considered to be too complex for the current application. The goal of this thesis was to develop a behavioral model, which would model the vapor chamber as one domain in the CFD simulation model. Experimental data was taken as the basis of the behavioral model. The measurements were done with a 0.6 mm vapor chamber and a 3 mm copper reference sample. The experimental setup was replicated into a commercial CFD simulation software and the model was tuned to match with the calibration sample. Then, using the tuned model, the thin vapor chamber was simulated by assuming various thermal conductivity values.Data from the simulations were compared to the experiments by using RMSE minimization. It produced a function that described how the vapor chamber's effective conductivity changes with temperature. To use the algorithm built into the CFD software, a linear approximation was applied to the function. The linearization provided parameters that enabled to create a temperature dependent material model that was used in the one cuboid behavioral model of the vapor chamber.ii TIIVISTELMÄ LAURI NIITTYMÄKI: Joustava höyrykammion simulointimalli mobiililaitteiden lämpösimulaatioihin Tampereen teknillinen yliopisto Diplomityö, 47 sivua Lokakuu 2016 Materiaalitekniikan diplomi-insinöörin tutkinto-ohjelma Pääaine: Materiaalitutkimus Tarkastaja: professori Veli-Tapani Kuokkala Avainsanat: höyrykammio, käyttäytymismalli, lämmönhallinta, lämmön levytys, simulointi, CFD, mobiililaite Kasvava laskentateho kannettavissa laitteissa nostaa myös niiden sisällä olevan elektroniikan tuottamaa lämpökuormaa. Laitteen suunnitteluvaiheessa lämmöntuotto pitää ottaa huomioon, jotta laitetta on turvallista käyttää. Simulointi on yksi työkaluista, joita käyte-tään suunnitteluvaiheessa löytämään paras ratkaisu. Se mahdollistaa erilaisten ratkaisujen kokeilun, ja ohjelmiston optimointityökalut auttavat parhaan ratkaisun löytämisessä.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Flexible CFD simulation model of a thin vapor chamber for mobile applications

Niittymaki¹,

Biber

Carbone

2016

2016 22nd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC)

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Cooling of arc furnace electrodes with heat pipes

Bullerschen

Wilhelmi

1991

Chem Eng & Technol

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Combination electrodes with water cooling shanks, which have been introduced to reduce graphite consumption in UHP furnaces, cause the danger of vapour explosions in case of breaking. Heat pipes are highly efficient two phase heat conductors which could provide a safer alternative to water cooling shanks, since they contain only a small amount of liquid. The transport of energy results from evaporation of the working fluid in the heated section, convection of the vapour to the cooled section and reflux of the condensed fluid to the heated end. Large heat quantities can be transferred under nearly isothermal conditions within the tube, as long as certain limits are not exceeded. The operating temperature can be controlled by design parameters such as the thermal resistance of the cooling zone. The proper function of heat pipes for cooling arc furnace electrodes is investigated by comparing the calculated heat load with temperature dependent limits to heat transport. It is shown that copper tubes with water as the working fluid combine efficient cooling and safe performance in the low temperature range, while the cheaper steel tubes with sodium filling are suitable for high temperature operation.

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Lifetest Investigations with Stainless Steel/Water Heat Pipes

Munzel

Krähling

1982

Advances in Heat Pipe Technology

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Compatibility and reliability of heat pipe materials

Cited by 15 publications

References 0 publications

Flexible CFD simulation model of a thin vapor chamber for mobile applications

Flexible CFD simulation model of a thin vapor chamber for mobile applications

Cooling of arc furnace electrodes with heat pipes

Lifetest Investigations with Stainless Steel/Water Heat Pipes

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