Performance of a Self-Circulating Thermosyphon

2011 ◽  
Author(s):  
Naoto Hagino ◽  
Hiro Yoshida
Keyword(s):  
Driving Force ◽  
Laboratory Experiments ◽  
Input Power ◽  
Present System ◽  
Filling Rate ◽  
Heating Section ◽  
Tilting Angle ◽  
Basic Performance ◽  
Startup Time ◽  
Water Filling

A series of laboratory experiments on self-circulating thermosyphon (SCT) was carried out. The thermosyphon system consists of heating section, condenser, reservoir, and heat exchanging section. The basic performance was elucidated. The present thermosyphon system works by itself under certain conditions of tilting angle of the condenser, the water filling rate, and the input power. The startup time of the present system is remarkably improved. The effect of the buoyancy on the driving force is indicated through the tilting angle of the condenser.

scholarly journals Sex overrides mutation in Escherichia coli colonizing the gut

2018 ◽  
Author(s):  
N. Frazão ◽  
A. Sousa ◽  
M. Lässig ◽  
I. Gordo
Keyword(s):  
Escherichia Coli ◽  
Experimental Evolution ◽  
Temporal Pattern ◽  
Driving Force ◽  
Laboratory Experiments ◽  
Rapid Evolution ◽  
Point Mutations ◽  
Natural Environments ◽  
E Coli ◽  
Accelerate Evolution

AbstractBacteria evolve by mutation accumulation in laboratory experiments, but the tempo and mode of evolution in natural environments are largely unknown. Here we show, by experimental evolution of E. coli in the mouse gut, that the ecology of the gut controls bacterial evolution. If a resident E. coli strain is present in the gut, an invading strain evolves by rapid horizontal gene transfer; this mode precedes and outweighs evolution by point mutations. An epidemic infection by two phages drives gene uptake and produces multiple co-existing lineages of phage-carrying (lysogenic) bacteria. A minimal dynamical model explains the temporal pattern of phage epidemics and their complex evolutionary outcome as generic effects of phage-mediated selection. We conclude that phages are an important eco-evolutionary driving force – they accelerate evolution and promote genetic diversity of bacteria.One Sentence SummaryBacteriophages drive rapid evolution in the gut.

Experimental study on the heat transfer performance of a stainless-steel heat pipe with sintered fiber wick

2021 ◽  
pp. 1-16
Author(s):  
Haijun Mo ◽  
Hang Zhao ◽  
Xiaowu Wang ◽  
Rui Cao ◽  
Zhenping Wan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Driving Force ◽  
Heat Transfer Performance ◽  
Zero Gravity ◽  
Transfer Performance ◽  
Filling Rate ◽  
Power Limit ◽  
Stainless Steel Heat ◽  
Steel Heat

Abstract A kind of stainless-steel heat pipe with sintered fiber wick is investigated with the aim to improve the heat dissipation when it is used in spent fuel pool in nuclear power plant. The effects of test angle, porosity and the filling rate on the heat transfer performance of the heat pipe are studied. At test angle 90°, the permeability plays an important role on the power limit since gravity can provide the necessary driving force. Larger porosity involves with poor heat conductivity although it results in better permeability. When test angle is zero gravity is no longer the driving force. In this case, the evaporation section can still avoid dry burning because part of the evaporation section is dipped in the deionized water. Therefore, permeability and filling ratio are two important factors influencing the power limit. Filling rate determines the vapor flowing space. When test angle is smaller than zero, gravity becomes resistance force. Then the lag tension and the filling rate exert greatest influence on the performance of the heat pipe. Smaller porosity corresponds to smaller contact angle.

scholarly journals Droplet Formation and Dripping Behavior during the Electroslag Remelting Process with Two Series-Connected Electrodes

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 386 ◽  
Author(s):  
Wenjie Tong ◽  
Wanming Li ◽  
Ximin Zang ◽  
Huabing Li ◽  
Zhouhua Jiang ◽  
...  
Keyword(s):  
Proximity Effect ◽  
Physical Simulation ◽  
Fluid Model ◽  
Metal Droplet ◽  
Droplet Formation ◽  
Input Power ◽  
Electroslag Remelting ◽  
Filling Rate ◽  
Molten Layer ◽  
Droplet Behavior

The formation and dripping behavior of droplets in the process of the electroslag remelting with two series-connected electrodes (TSCE-ESR) has an important influence on the optimization of power supply parameters and the purity of the electroslag ingot. In this article, through numerical simulation based on the VOF (volume of fluid) model, combined with the transparent experimental device for physical simulation, the mechanism of metal droplet formation and the effect of the filling rate on its droplet behavior were studied. The results showed that the proximity effect, instead of the skin effect, is a major factor influencing droplet formation in TSCE-ESR process. The proximity effect makes the region inside the two electrode tip melt first, and the molten steel converges at the electrode tips to form a droplet source. The process of droplet formation and dropping can be divided into three stages: formation of molten layer, droplet stretching and necking, and detachment. In the stage of droplet stretching and necking, the increase in the contact area between the droplet and the slag and the instantaneous increase of the current provide good thermodynamic and dynamic conditions for the removal of non-metallic inclusions. After the droplet drops into the slag pool, it promotes the flow of slag and improves the heat and mass transfer efficiency of the slag/metal interface. The relatively large filling rate can form smaller and dispersed droplets, which improves the refining effect. At the same time, the increase of the filling rate can improve the input power and the electrode remelting rate.

Osmotic Pressure Modeling of White Wine Diafiltration and Red Wine Concentration by Reverse Osmosis

2006 ◽  
Vol 2 (1) ◽  
pp. 119-132 ◽  
Author(s):  
László Takács ◽  
Gyula Vatai
Keyword(s):  
Osmotic Pressure ◽  
Reverse Osmosis ◽  
Driving Force ◽  
Laboratory Experiments ◽  
Red Wine ◽  
Membrane Separation ◽  
Sugar Content ◽  
White Wine ◽  
Empirical Relations ◽  
Concrete Model

During our research concentrations of quality wines were investigated by membrane separation on nanofiltration and reverse osmosis membranes. The practicability of the process was examined by experimental design in our laboratory experiments. The effects of the operating parameters on the efficiency of the methods were analyzed, from which the conclusion was drawn that the sugar content of the wines affects the filtrate capacity considerably. This phenomenon was attributed to the resistance appearing during the process. This resistance is the osmotic pressure which is faced with the driving force. By the mathematical modeling of the process - building up experimental and empirical relations - the answer for the practical implementing was searched for. Our concrete model concentrates on the connection between the changing of the osmotic pressure and the retained molecules by the membrane. Monitoring of this connection is a primary criterion when planning the optimal development of the process.

Study of Influence Effect on Heat Transfer Performance of Single-Loop Oscillating Heat Pipe

2014 ◽  
Vol 535 ◽  
pp. 114-118 ◽  
Author(s):  
Su Lei
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Filling Rate ◽  
Oscillating Heat Pipe ◽  
Heating Section ◽  
Cooling Section

s. The experiment studied the effect of heat source temperature, heating section length ratio, cooling air flow rate, liquid filling rate and pipe diameter on the heat transfer performance of the single-loop red copper-water oscillating heat pipe. The results show that increasing heat source temperature or pipe diameter and reducing filling rate can obviously reduce the thermal resistance of the heat pipe; in the air cooling mode, the cooling thermal resistance outside the pipe is affected by both cooling conditions and heat pipe cooling section average temperature; when the heating section is shorter than the cooling section, the heat pipe thermal resistance shows an apparent trend of increasing with the increase of heating section length ratio, when the heating section is longer than the cooling section, the cooling thermal resistance increases with it apparently; the heat transfer power is the highest when the filling rate is 50%.

Covering of cometary nucleus by refractory crust and its evolution into asteroid-like body

1999 ◽  
Vol 173 ◽  
pp. 365-370
Author(s):  
Kh.I. Ibadinov
Keyword(s):  
Laboratory Experiments ◽  
Cometary Nucleus ◽  
Sublimation Rate ◽  
Cometary Nuclei ◽  
Short Period Comet ◽  
Short Period ◽  
Brightness Decrease ◽  
Crust Thickness ◽  
Ice Sublimation ◽  
Period Comet

AbstractFrom the established dependence of the brightness decrease of a short-period comet dependence on the perihelion distance of its orbit it follows that part of the surface of these cometary nuclei gradually covers by a refractory crust. The results of cometary nucleus simulation show that at constant insolation energy the crust thickness is proportional to the square root of the insolation time and the ice sublimation rate is inversely proportional to the crust thickness. From laboratory experiments resulted the thermal regime, the gas productivity of the nucleus, covering of the nucleus by the crust, and the tempo of evolution of a short-period comet into the asteroid-like body studied.

Two-photon excitation microscopy in cellular biophysics

1995 ◽  
Vol 53 ◽  
pp. 62-63
Author(s):  
David W. Piston ◽  
Brian D. Bennett ◽  
Robert G. Summers
Keyword(s):  
Confocal Microscopy ◽  
Laser Beam ◽  
Duty Cycle ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10-5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

The nucleation of cavities at grain boundaries

1987 ◽  
Vol 45 ◽  
pp. 288-291
Author(s):  
P. J. Goodhew
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Grain Boundaries ◽  
Radiation Damage ◽  
Impurity Concentration ◽  
Driving Force ◽  
Nucleation And Growth ◽  
Phase Boundaries ◽  
Cavity Nucleation ◽  
Spherical Bubble

Cavity nucleation and growth at grain and phase boundaries is of concern because it can lead to failure during creep and can lead to embrittlement as a result of radiation damage. Two major types of cavity are usually distinguished: The term bubble is applied to a cavity which contains gas at a pressure which is at least sufficient to support the surface tension (2g/r for a spherical bubble of radius r and surface energy g). The term void is generally applied to any cavity which contains less gas than this, but is not necessarily empty of gas. A void would therefore tend to shrink in the absence of any imposed driving force for growth, whereas a bubble would be stable or would tend to grow. It is widely considered that cavity nucleation always requires the presence of one or more gas atoms. However since it is extremely difficult to prepare experimental materials with a gas impurity concentration lower than their eventual cavity concentration there is little to be gained by debating this point.

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