PTFE Modification to Enhance Boiling Performance of Porous Surface

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Ya-Qiao Wang ◽  
Jia-Li Luo ◽  
Yi Heng ◽  
Dong-Chuan Mo ◽  
Shu-Shen Lyu
Keyword(s):  
Boiling Heat Transfer ◽  
Heat Dissipation ◽  
Flat Surface ◽  
Hydrophobic Surface ◽  
High Heat ◽  
High Heat Flux ◽  
Pin Fin ◽  
Original Surface ◽  
Wall Superheat ◽  
Hybrid Modification

Abstract Boiling heat transfer is one of the most effective methods to meet the challenge of heat dissipation of high heat flux devices. A wetting hybrid surface has been shown to have better performance than the hydrophilic or hydrophobic surface. This kind of wetting hybrid modification is always carried out on a plain or flat surface. In this paper, polytetrafluoroethylene (PTFE) powders were coated on a superhydrophilic microcopper dendrite fin surface to build a wetting hybrid surface. The pool-boiling experimental results showed that after applying the coating, the wall superheat dramatically decreased to 8 K, which is 9 K lower than that on the original surface at 250 W·cm−2, and has a better performance than a silicon pin-fin-based wetting hybrid surface.

PTFE Modification to Enhance Boiling Performance of Porous Surface

2019 ◽  
Author(s):  
Ya-Qiao Wang ◽  
Jia-Li Luo ◽  
Yi Heng ◽  
Dong-Chuan Mo ◽  
Shu-Shen Lyu
Keyword(s):  
Boiling Heat Transfer ◽  
Heat Dissipation ◽  
Flat Surface ◽  
Hydrophobic Surface ◽  
High Heat ◽  
High Heat Flux ◽  
Pin Fin ◽  
Original Surface ◽  
Wall Superheat ◽  
Hybrid Modification

Abstract Boiling heat transfer is one of the most effective methods to meet the challenge of heat dissipation of high heat flux devices. Wetting hybrid surface has been demonstrated to have better performance than hydrophilic or hydrophobic surface. But this kind of wetting hybrid modification is always carried out on plain or flat surface. In this paper, we coated PTFE powders on superhydrophilic micro copper dendrite fin surface to build wetting hybrid surface. The pool boiling experimental results showed that after coating, the wall superheat dramatically decreased to 8 K, which is 9K lower than that on original surface at 250 W·cm−2. Besides, it also has much better performance than Silicon pin fin based wetting hybrid surface.

Effect of Heat Sink Structure Improvement on Heat Dissipation Performance in High Heat Flux

2016 ◽  
Author(s):  
Zhuo Cui
Keyword(s):  
Heat Resistance ◽  
Water Flow ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Convection Heat Transfer ◽  
Cooling Water ◽  
High Heat Flux ◽  
Pin Fin ◽  
Pin Fins ◽  
Pin Fin Arrays

This paper presents the effects of heat dissipation performance of pin fins with different heat sink structures. The heat dissipation performance of two types of pin fin arrays heat sink are compared through measuring their heat resistance and the average Nusselt number in different cooling water flow. The temperature of cpu chip is monitored to determine the temperature is in the normal range of working temperature. The cooling water flow is in the range of 0.02L/s to 0.15L/s. It’s found that the increase of pin fins in the corner region effectively reduce the temperature of heat sink and cpu chip. The new type of pin fin arrays increase convection heat transfer coefficient and reduce heat resistance of heat sink.

Experimental Investigation of Boiling Heat Transfer in a Liquid Chamber With Partially Soluble Nanofluids

2021 ◽  
Author(s):  
Noriyuki Unno ◽  
Kazuhisa Yuki ◽  
Risako Kibushi ◽  
Rika Nogita ◽  
Atsuyuki Mitani
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Electronic Devices ◽  
High Heat ◽  
Experimental Result ◽  
High Heat Flux ◽  
Promising Technique ◽  
Cooling Device ◽  
Cooling Devices

Abstract Boiling heat transfer (BHT) is a promising technique to remove a high heat flux emitted from next-generation electronic devices. However, critical heat flux (CHF) is a big problem in BHT because it restricts the maximum performance of the cooling devices using BHT. Nanofluid has been widely used to improve the CHF. In this study, the authors investigated the BHT of a compact cooling device at low pressure using a special nanofluid: that is made with partially soluble particles in water. The experimental result found that the CHF with the special nanofluid is 170 W/cm2 and is higher than that with nanofluid made with an insoluble nanoparticle.

scholarly journals A Study on the Boiling Heat Transfer from Flat Surfaces under High Heat Flux : 1st Report, Burnout Heat Flux

1962 ◽  
Vol 28 (189) ◽  
pp. 587-595
Author(s):  
Seikan ISHIGAI ◽  
Kiyoshi INOUE ◽  
Akiharu KAWABATA ◽  
Yutaka SADAMORI ◽  
Zyumei KIWAKI ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
High Heat ◽  
High Heat Flux ◽  
Flat Surfaces

scholarly journals Experimental Investigation of Compact Evaporators for Ultralow Temperature Refrigeration of Microprocessors

2007 ◽  
Vol 129 (3) ◽  
pp. 291-299 ◽  
Author(s):  
Robert Wadell ◽  
Yogendra K. Joshi ◽  
Andrei G. Fedorov
Keyword(s):  
High Heat ◽  
Heat Fluxes ◽  
Junction Temperature ◽  
High Heat Flux ◽  
Base Line ◽  
Vapor Compression ◽  
Pin Fin ◽  
Slit Flow ◽  
Strong Motivation ◽  
Pin Fin Array

Microprocessor performance can be significantly improved by lowering the junction temperature, especially down to the deep subambient levels. This provides the strong motivation for the current study, which focuses on the design and thermohydraulic performance evaluation of high heat flux evaporators suitable for interfacing the microprocessor chip with a cascaded R134a∕R508b vapor compression refrigeration system at −80°C. Four compact evaporator designs are examined—a base line slit-flow structure with no microfeatures, straight microchannels, an inline pin fin array, and an alternating pin fin array—all fitting the same size envelope. Pressure drop and heat transfer measurements are reported and discussed to explain the performance of the various evaporator geometries for heat fluxes ranging between 20W∕cm2 and 100W∕cm2.

Fabrication and Performance of a Pin Fin Micro Heat Exchanger

2004 ◽  
Vol 126 (3) ◽  
pp. 434-444 ◽  
Author(s):  
Christophe Marques ◽  
Kevin W. Kelly
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Heat Exchangers ◽  
Turbine Blades ◽  
High Heat ◽  
Gas Turbine Engine ◽  
High Heat Flux ◽  
Turbine Engine ◽  
Pin Fin ◽  
Micro Heat Exchanger

Nickel micro pin fin heat exchangers can be electroplated directly onto planar or non-planar metal surfaces using a derivative of the LIGA micromachining process. These heat exchangers offer the potential to more effectively control the temperature of surfaces in high heat flux applications. Of particular interest is the temperature control of gas turbine engine components. The components in the gas turbine engine that require efficient, improved cooling schemes include the gas turbine blades, the stator vanes, the turbine disk, and the combustor liner. Efficient heating of component surfaces may also be required (i.e., surfaces near the compressor inlet to prevent deicing). In all cases, correlations providing the Nusselt number and the friction factor are needed for such micro pin fin heat exchangers. Heat transfer and pressure loss experimental results are reported for a flat parallel plate pin fin micro heat exchanger with a staggered pin fin array, with height-to-diameter ratios of 1.0, with spacing-to-diameter ratios of 2.5 and for Reynolds numbers (based on the hydraulic diameter of the channel) from 4000 to 20,000. The results are compared to studies of larger scale, but geometrically similar, pin fin heat exchangers. To motivate further research, an analytic model is described which uses the empirical results from the pin fin heat exchanger experiments to predict a cooling effectiveness exceeding 0.82 in a gas turbine blade cooling application. As a final point, the feasibility of fabricating a relatively complex micro heat exchanger on a simple airfoil (a cylinder) is demonstrated.

scholarly journals Visualization Experimental Study on Silicon-Based Ultra-Thin Loop Heat Pipe Using Deionized Water as Working Fluid

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1080
Author(s):  
Wenzhe Song ◽  
Yanfeng Xu ◽  
Lihong Xue ◽  
Huajie Li ◽  
Chunsheng Guo
Keyword(s):  
Heat Pipe ◽  
Heat Dissipation ◽  
Experimental System ◽  
High Heat ◽  
Deionized Water ◽  
Working Fluid ◽  
Stable Operation ◽  
High Heat Flux ◽  
Loop Heat Pipe ◽  
Silicon Based

As a type of micro flat loop heat pipe, s-UTLHP (silicon-based ultra-thin loop heat pipe) is of great significance in the field of micro-scale heat dissipation. To prove the feasibility of s-UTLHP with high heat flux in a narrow space, it is necessary to study its heat transfer mechanism visually. In this paper, a structural design of s-UTLHP was proposed, and then, to realize the working fluid charging and visual experiment, an experimental system including a holding module, heating module, cooling module, data acquisition module, and vacuum chamber was proposed. Deionized water was selected as a working fluid in the experiment. The overall and micro phenomena of s-UTLHP during startup, as well as the evaporation and condensation phenomena of s-UTLHP during stable operation, were observed and analyzed. Finally, the failure phenomenon of s-UTLHP was analyzed, and several solutions were proposed. The observed phenomena and experimental conclusions can provide references for further related experimental research.

A Mathematical Modeling Method for Capillary Limit of Micro Heat Pipe with Sintered Wick

2011 ◽  
Vol 175 ◽  
pp. 335-341
Author(s):  
Xi Bing Li ◽  
Chang Long Yang ◽  
Gong Di Xu ◽  
Wen Yuan ◽  
Shi Gang Wang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Pipe ◽  
Heat Dissipation ◽  
High Heat ◽  
Experimental Investigations ◽  
High Heat Flux ◽  
Micro Heat Pipe ◽  
Copper Powders ◽  
Capillary Limit

With heat flux increasing and cooling space decreasing in microelectronic and chemical products, micro heat pipe has become an ideal heat dissipation device in high heat-flux products. Through the analysis of its working principle, the factors that affect its heat transfer limits and the patterns in which copper powders are arrayed in circular cavity, this paper first established a mathematical model for the crucial factors in affecting heat transfer limits in a circular micro heat pipe with a sintered wick, i.e. a theoretical model for capillary limit, and then verified its validity through experimental investigations. The study lays a powerful theoretical foundation for designing and manufacturing circular micro heat pipes with sintered wicks.

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