scholarly journals Marangoni Convection and Thin-Film Evaporation in Microstructured Wicks for Heat Pipes

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Ram Ranjan ◽  
Jayathi Y. Murthy ◽  
Suresh V. Garimella
Keyword(s):  
Thin Film ◽  
Marangoni Convection ◽  
Heat Pipes ◽  
Thin Film Evaporation ◽  
Film Evaporation

Investigation of Thin Film Evaporation Limit in Single Screen Mesh Layer

2002 ◽  
Author(s):  
Y. X. Wang ◽  
G. P. Peterson
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Pipes ◽  
Liquid Meniscus ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Evaporation Heat ◽  
Heat Transfer Limit ◽  
Evaporation Heat Transfer ◽  
Screen Mesh

Thin film evaporation heat transfer plays an extremely important role in capillary microstructures of the type used extensively in micro heat pipes, loop heat pipes and high-flux film heat spreaders. Because the formation of the liquid meniscus in the pore cell has a significant effect on the evaporation process occurring at the interface of the liquid meniscus, it is necessary to investigate the mechanisms and limitations of the phase-change phenomena occurring in the thin layer. In the current study, an analytical model, which combines the heat conduction in the wick layer with bubble formation mechanisms in the capillary structure, has been developed to determine the evaporation heat transfer limit. Temperature distribution, superheat, and heat flux distribution in the liquid meniscus area are investigated for a single layer of metal screen mesh. The wire diameter, the space between the wires and the contact conditions between the solid wall and mesh layer is shown to have a significant effect on the evaporation limit and capillary force. Results indicated that evaporation takes place mainly in the thin film region, and the heat transfer coefficient is much higher in this area than in the intrinsic region. The evaporation limit is restrained by the formation of the liquid meniscus, and the higher the capillary pressure, the lower the evaporation heat transfer limit.

Comparison of 4 Methods for Scalable Kinetic (Fast) Vitrification of Cells: From Theoretical Considerations to Feasibility and Practicality

2013 ◽  
Author(s):  
Igor I. Katkov ◽  
Vladimir F. Bolyukh ◽  
Stephen B. Jones ◽  
Vsevolod Katkov
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Heat Pipes ◽  
Thin Film Evaporation ◽  
Ultra Fast Cooling ◽  
Film Evaporation ◽  
Fast Cooling ◽  
Rate Of Cooling ◽  
Theoretical Considerations ◽  
Fast Rates

Kinetic (very rapid) vitrification (K-VF) is a promising approach for cryopreservation (CP) of cells but existing methods are not scalable due to the Liedenfrost effect (LFE), which substantially impedes the rate of cooling. Here, we compare 4 emerging approaches that discuss scalability and ultra-fast cooling, namely, cryogenic oscillating heat pipes (COHP), microstructured evaporation in thin films, K-VF in nanodroplets and thin film evaporation in microstructured with our methods of hyperfast cooling KrioBlastTM. We show that only KrioBlastTM can ensure hyper-fast rates of cooling by elimination of the LFE. The logistics and other aspects of practicality of 4 methods are also discussed.

An Ultrafast Vitrification Method for Cell Cryopreservation

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Fengmin Su ◽  
Nannan Zhao ◽  
Yangbo Deng ◽  
Hongbin Ma
Keyword(s):  
Thin Film ◽  
Cooling Rate ◽  
Experimental Results ◽  
Low Concentration ◽  
Temperature Range ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
A Cell ◽  
Cryoprotective Solution ◽  
Ultrafast Cooling

Ultrafast cooling is the key to successful cell vitrification cryopreservation of lower concentration cryoprotective solution. This research develops a cell cryopreservation methodology which utilizes thin film evaporation and achieves vitrification of relatively low concentration cryoprotectant with an ultrafast cooling rate. Experimental results show that the average cooling rate of dimethylsulfoxide (DMSO) cryoprotective solution reaches 150,000 °C/min in a temperature range from 10 °C to −180 °C. The ultrafast cooling rate can remarkably improve the vitrification tendencies of the cryoprotective solution. This methodology opens the possibility for more successful cell vitrification cryopreservation.

Theoretical Analysis of Thin Film Evaporation in the Wicks of Loop Heat Pipes

2021 ◽  
pp. 1-14
Author(s):  
Bingyao Lin ◽  
Nanxi Li ◽  
Shiyue Wang ◽  
Leren Tao ◽  
Guangming Xu ◽  
...  
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Pore Size ◽  
Momentum Conservation ◽  
Loop Heat Pipes ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Quantity Of Heat

Abstract In this paper, a thin film evaporation model that includes expressions for energy, mass and momentum conservation was established through the augmented Young-Laplace model. Based on this model, the effects of pore size and superheating on heat transfer during thin film evaporation were analyzed. The influence of the wick diameter of the loop heat pipe (LHP) on the critical heat flux of the evaporator is analyzed theoretically. The results show that pore size and superheating mainly influence evaporation through changes in the length of the transition film and intrinsic meniscus. The contribution of the transition film area is mainly reflected in the heat transfer coefficient, and the contribution of the intrinsic meniscus area is mainly apparent in the quantity of heat that is transferred. When an LHP evaporator is operating in a state of surface evaporation, a higher heat transfer coefficient can be achieved using a smaller pore size.

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