Evaporation time and vapor generation limit of a droplet on a hot surface

2021 ◽  
Vol 173 ◽  
pp. 121280
Author(s):  
Y. Liu ◽  
M. Monde ◽  
Y. Mitsutake ◽  
K. Tsubaki
Keyword(s):  
Evaporation Time ◽  
Vapor Generation ◽  
Hot Surface

B222 Rapid vapor generation during contact of a liquid droplet with a hot surface

2009 ◽  
Vol 2009 (0) ◽  
pp. 227-228
Author(s):  
Takuya Nishida ◽  
Yuichi Mitsutake ◽  
Masanori Monde ◽  
Akikazu Kurihara
Keyword(s):  
Liquid Droplet ◽  
Vapor Generation ◽  
Hot Surface

Evaporation Time of Gasoline and Diesel Fuel Droplets on a Hot Plate: The Influence of Fuel Deposits

2008 ◽  
Author(s):  
P. Seers ◽  
V. Reguillet ◽  
E. Plamondon ◽  
L. Dufresne ◽  
S. Halle´
Keyword(s):  
Diesel Fuel ◽  
Droplet Evaporation ◽  
Evaporation Time ◽  
Plate Temperature ◽  
Diesel Fuels ◽  
Fuel Droplets ◽  
Initial Fuel ◽  
Property Changes ◽  
Fuel Evaporation ◽  
Hot Surface

The objective of this paper is to present experimental results of multicomponent fuel droplets impinging on a hot surface in order to quantify the influence of fuel build-up deposits on the evaporation time. The experiments were conducted with gasoline and diesel fuels to first obtain curves of evaporation time as a function of plate temperature. Based on these curves the Nukiyama and Leindenfrost temperatures were identified. In a second step, the effect of fuel deposit on the droplet evaporation time was studied. Based on the above evaporation time curves, plate temperatures were chosen as to offer a similar evaporation time but at temperatures below and above the Nukiyama and Leindenfrost temperatures respectively. This was done in order to isolate the effect of fuel deposits from the different evaporation mechanisms. The evaporation of successive impinging droplets was then measured. The results hence obtained indeed showed that the fuel deposit has a different impact on the evaporation time according the evaporating mechanism or equivalently the plate temperature. For plate temperatures lower than the Nukiyama temperature, gasoline and diesel fuel droplets showed an increase of their evaporation time as the amount of successive impinging droplets increased. The trend was reversed for plate temperatures above the Leindenfrost temperature. A hypothesis for this latter case is that the fuel deposit disrupts the vapor layer supporting the droplet and therefore provides a greater heat flux to the evaporating droplet. Finally, droplet evaporation times as a function of plate temperature were measured with an initial fuel deposit covering the plate. These results in turn showed that the global thermal diffusivity and porosity of the surface are changed by the presence of the fuel deposit. The consequence of these property changes are then shown to have a direct and global impact on the fuel evaporation time curves.

The Leidenfrost Phenomenon on Silicon Nanowires

2016 ◽  
Author(s):  
Manuel Auliano ◽  
Maria Fernandino ◽  
Peng Zhang ◽  
Carlos Alberto Dorao
Keyword(s):  
Heat Transfer ◽  
Silicon Nanowires ◽  
Droplet Evaporation ◽  
Vapor Layer ◽  
Si Nanowires ◽  
Evaporation Time ◽  
Nanostructured Surfaces ◽  
Leidenfrost Temperature ◽  
Efficient Heat Transfer ◽  
Hot Surface

In this paper, the effect of Si nanowires on the Leidenfrost point on impacting water droplet is presented. In the Leidenfrost regime, the low thermal conductivity of the vapor layer hinders the heat transfer from the hot surface. Nanostructured surfaces can dramatically increase the Leidenfrost temperature improving heat transfer at high temperature. To determine the point of the minimum efficient heat transfer, the droplet lifetime method was employed for both the polished and processed surfaces. The cooling performance was discussed in terms of the droplet evaporation time. The surface with the tallest NWs structure yielded the highest shift in the Leideinfrost point, about 156 % higher than a plain Si surface.

scholarly journals The effect of pressure and frequency on the dynamic behavior and evaporation time of successive water droplets impacting onto hot surface

2018 ◽  
Vol 154 ◽  
pp. 01107 ◽  
Author(s):  
Teguh Wibowo ◽  
Arif Widyatama ◽  
Samsul Kamal ◽  
Indarto ◽  
Deendarlianto
Keyword(s):  
High Speed ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Water Tank ◽  
Water Droplets ◽  
Cooling Process ◽  
Surface Cooling ◽  
Evaporation Time ◽  
Effect Of Pressure ◽  
Hot Surface

Multiple droplets are the drop of water which continuously dropped on a surface in certain time difference. The phenomenon droplets impacting a solid surface can be found in a various field, one of them is the cooling process in the metal industry. The cooling process is carried out by spraying a number of water droplets to hot surface until it reaches the desired condition. When droplets impinge on the surface, the dynamics of droplets, such as the spreading and recoil phenomena, depend on some properties. In this study, the effect of pressure and drop frequency to the droplet characteristics as well as cooling effectiveness will be investigated. Visualization process is used to find maximum spreading which can indicate the effectiveness of hot surface cooling. The experiment is performed by setting the distance of water tank and nozzle into 100cm, 150cm and 200cm while the frequency of droplets is set at 245, 386, and 623 drops/minute. The material used in the present work is Stainless Steel with the temperature ranged from 100°C - 220°C. In addition, image processing technique is applied to gather the quantitative data from the images that successfully taken by using high-speed camera. Based on the study, it is found that the pressure of water tank affects the frequency of generated droplet. Furthermore, the frequency of droplet impacting onto the hot surface also influences the evaporation time.

Evaporation of Liquid Marbles on a Heated Surface: Coating-Assisted Leidenfrost Phenomenon

2011 ◽  
Author(s):  
Cedric Aberle ◽  
Mark Lewis ◽  
Gan Yu ◽  
Nan Lei ◽  
Jie Xu
Keyword(s):  
Heat Transfer ◽  
Liquid Core ◽  
Film Boiling ◽  
Vapor Film ◽  
Water Droplets ◽  
Evaporation Time ◽  
Liquid Marbles ◽  
Leidenfrost Effect ◽  
Surface Liquid ◽  
Hot Surface

The Leidenfrost effect is a well-known heat transfer phenomenon, which predicts that liquid droplets will show prolonged evaporation time when they are placed on a hot surface with a temperature higher than a critical value. This effect is due to film boiling, where a vapor film helps insulate the drop from the hot surface. In this paper, we show that specially engineered droplets — liquid marbles — can exhibit Leifenfrost effect at any temperature above the boiling point without experiencing any transition. Liquid marbles are spheres with a liquid core that are coated with hydrophobic particles. When brought into contact with a solid surface, liquid marbles are completely nonwetting due to the fact that the hydrophobic powder is in between the liquid and solid surface. Liquid marbles may be used as excellent microreservoirs for biosample handling and chemical reagent manipulation. In our study, liquid marbles are synthesized by coating water droplets with graphite particles. We investigate the thermal evaporation of the fabricated graphite liquid marbles on a hot substrate at prescribed temperatures, and compare the results with pure water droplets. The evaporation time of both liquid marbles and water droplets are recorded at various temperatures. If the temperature is above the Leidenfrost point, the evaporation of both liquid marbles and water droplets are prolonged with similar amount of time (about 100s), which indicates that similar physics might at play in both cases: heat transfer is impeded by a thin layer of vapor. If the temperature is below the Leidenfrost point, water droplets evaporate a hundred times faster. This is because the vapor film cannot self-sustain and levitate the droplet anymore. On the other hand, liquid marbles still evaporate slowly with the same level of time as Leidenfrost evaporation times, which indicates that the Leidenfrost effect still takes effect for liquid marbles even below the critical temperature. This might be due to the fact that the coating of the liquid marble helps levitate the liquid core, maintaining a layer of insulating vapor. In the end, we report detailed deformation of liquid marbles during evaporation. This coating-assisted Leidenfrost phenomenon could be useful in many applications where film boiling is desired. The strong thermal robustness of graphite liquid marbles over a wide temperature range, together with the inert reactivity, electrical conductivity and superior lubrication properties of graphite, make graphite liquid marbles potentially useful in a wealth of applications in microfluidics and lab on a chip devices.

Investigation of Reaction Products Obtained from Ignition Process of n-Heptane / Air Mixtures on Free Hot Surface

2017 ◽  
Vol 68 (5) ◽  
pp. 1035-1039
Author(s):  
Maria Mitu ◽  
Elisabeth Brandes
Keyword(s):  
Stainless Steel ◽  
Ignition Temperature ◽  
Ambient Pressure ◽  
Ignition Process ◽  
Reaction Products ◽  
Hot Surface

The ignition behaviour at ambient pressure (p0 between 98.0 kPa and 101.3 kPa) of different concentrations of homogenous n-heptane/air mixtures on stainless steel hot surface as well as the composition of the reaction products have been investigated. Although all reaction products are present in each burned n-heptane/air mixture, a correlation between the lowest ignition temperature and the quantitve composition of the reaction products is not obvious.

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