scholarly journals The nucleation behavior of supercooled water vapor in helium

2002 ◽  
Vol 117 (12) ◽  
pp. 5647-5653 ◽  
Author(s):  
P. Peeters ◽  
J. J. H. Gielis ◽  
M. E. H. van Dongen
Keyword(s):  
Water Vapor ◽  
Supercooled Water ◽  
Nucleation Behavior

Electrical Supercooling Mitigation in Erythritol

2010 ◽  
Author(s):  
Nicholas R. Jankowski ◽  
F. Patrick McCluskey
Keyword(s):  
Electric Current ◽  
Crystallization Behavior ◽  
Supercooled Water ◽  
Heat Of Fusion ◽  
Recrystallization Temperature ◽  
Nucleation Behavior ◽  
Direct Electric Current ◽  
Surface Control ◽  
Before And After ◽  
High Latent Heat

This report describes an experimental investigation into the effect of electric current in reducing the supercooling of erythritol. Previous studies have identified erythritol as a prime material candidate for moderate temperature thermal energy storage (TES) systems due to its high latent heat of fusion and melting temperature (118°C), but it has also shown excessive supercooling, sometimes exceeding 65°C [1]. Various methods for controlling or reducing supercooling are reviewed, including work by Shichiri and Hozumi showing that a small electric current passed through supercooled water is highly effective in initiating nucleation [2,3]. In the present study, the authors demonstrate a similar effect with erythritol by subjecting a sample to repeated thermal cycles with and without the application of a direct electric current. The control cases without electric current showed a highly variable recrystallization temperature ranging from 67°C to 109°C (or supercooling magnitudes from 9 to 51°C). Passing a direct current through the sample using silver wire electrodes significantly shifted the material’s nucleation behavior. The local nucleation temperature only varied from 108°C to 112°C (or 6–10°C of supercooling), and nucleation always occurred on the positive electrode surface. Control cases both before and after the electrical trials indicated no noticeable change in sample crystallization behavior.

scholarly journals Freezing of water droplets colliding with kaolinite particles

2009 ◽  
Vol 9 (13) ◽  
pp. 4295-4300 ◽  
Author(s):  
E. A. Svensson ◽  
C. Delval ◽  
P. von Hessberg ◽  
M. S. Johnson ◽  
J. B. C. Pettersson
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Water Droplet ◽  
Supercooled Water ◽  
Dust Particles ◽  
Freezing Process ◽  
Water Droplets ◽  
Electrodynamic Balance ◽  
Dry Conditions

Abstract. Contact freezing of single supercooled water droplets colliding with kaolinite dust particles has been investigated. The experiments were performed with droplets levitated in an electrodynamic balance at temperatures from 240 to 268 K. Under relatively dry conditions (when no water vapor was added) freezing was observed to occur below 249 K, while a freezing threshold of 267 K was observed when water vapor was added to the air in the chamber. The effect of relative humidity is attributed to an influence on the contact freezing process for the kaolinite-water droplet system, and it is not related to the lifetime of the droplets in the electrodynamic balance. Freezing probabilities per collision were derived assuming that collisions at the lowest temperature employed had a probability of unity. Mechanisms for contact freezing are briefly discussed.

The Effect of Relative Humidity on the Nucleating Properties of Photolyzed Silver Iodide *

1952 ◽  
Vol 33 (10) ◽  
pp. 431-434 ◽  
Author(s):  
S. J. Birstein
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Ultraviolet Light ◽  
Silver Iodide ◽  
Supercooled Water ◽  
Adsorbed Water ◽  
Ice Formation ◽  
Water Droplets ◽  
Bright Sunlight ◽  
A Cell

The effect of adsorbed water vapor on the photolysis of silver iodide has been studied. Inn has found that when silver iodide nuclei are exposed to ultraviolet light before injection into a cold chamber containing a cloud of supercooled water droplets, no ice formation is observed. Reynolds, Hume, Vonnegut and Schaefer have investigated the effect of bright sunlight on the action of silver iodide as a sublimation nucleus, and have found a decrease in the magnitude of nucleating effectiveness which is less than that observed by Inn. The studies in this laboratory have been concerned with the effect of relative humidity on the photolysis and subsequent nucleating properties of silver iodide particles. Known amounts of water vapor were introduced into a stream of nitrogen passing over a silver iodide generator. The silver iodide particles, covered with adsorbed water, were collected in a cell and exposed to ultraviolet light of known intensity for varying amounts of time. After irradiation, the silver iodide particles were injected into a cloud of supercooled water droplets and ice formation was watched for. The nucleating effectiveness of silver iodide exposed to ultraviolet light was found to be directly dependent on the relative humidity of the gas stream passing over the generator.

New Design for a Differentially Pumped Hydration Chamber for a Siemens IA

1971 ◽  
Vol 29 ◽  
pp. 44-45
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Water Vapor ◽  
Electron Diffraction ◽  
Water Vapor Pressure ◽  
Biological Materials ◽  
Thin Membrane ◽  
Reliable System ◽  
System A ◽  
Water Films ◽  
Aperture Opening

Electron microscopy and diffraction of biological materials in the hydrated state requires the construction of a chamber in which the water vapor pressure can be maintained at saturation for a given specimen temperature, while minimally affecting the normal vacuum of the remainder of the microscope column. Initial studies with chambers closed by thin membrane windows showed that at the film thicknesses required for electron diffraction at 100 KV the window failure rate was too high to give a reliable system. A single stage, differentially pumped specimen hydration chamber was constructed, consisting of two apertures (70-100μ), which eliminated the necessity of thin membrane windows. This system was used to obtain electron diffraction and electron microscopy of water droplets and thin water films. However, a period of dehydration occurred during initial pumping of the microscope column. Although rehydration occurred within five minutes, biological materials were irreversibly damaged. Another limitation of this system was that the specimen grid was clamped between the apertures, thus limiting the yield of view to the aperture opening.

Hydration Chamber for Jeolco 200 Kv Microscope

1970 ◽  
Vol 28 ◽  
pp. 542-543
Author(s):  
V. R. Matricardi ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscope ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Pressure Gradient ◽  
Room Temperature ◽  
List Type ◽  
Type Number ◽  
Equilibrium Vapor Pressure

In order to observe room temperature hydrated specimens in an electron microscope, the following conditions should be satisfied: The specimen should be surrounded by water vapor as close as possible to the equilibrium vapor pressure corresponding to the temperature of the specimen.The specimen grid should be inserted, focused and photo graphed in the shortest possible time in order to minimize dehydration.The full area of the specimen grid should be visible in order to minimize the number of changes of specimen required.There should be no pressure gradient across the grid so that specimens can be straddled across holes.Leakage of water vapor to the column should be minimized.

Warm and freeze-fracture of cotton seed radicles

1987 ◽  
Vol 45 ◽  
pp. 984-985
Author(s):  
E. L. Vigil ◽  
E. F. Erbe
Keyword(s):  
Thin Film ◽  
Water Vapor ◽  
Fracture Surface ◽  
Membrane Structure ◽  
Room Temperature ◽  
Freeze Fracture ◽  
Longitudinal Axis ◽  
Fracture Plane ◽  
Cotton Seeds ◽  
Condensed Water

In cotton seeds the radicle has 12% moisture content which makes it possible to prepare freeze-fracture replicas without fixation or cryoprotection. For this study we have examined replicas of unfixed radicle tissue fractured at room temperature to obtain data on organelle and membrane structure.Excised radicles from seeds of cotton (Gossyplum hirsutum L. M-8) were fractured at room temperature along the longitudinal axis. The fracture was initiated by spliting the basal end of the excised radicle with a razor. This procedure produced a fracture through the tissue along an unknown fracture plane. The warm fractured radicle halves were placed on a thin film of 100% glycerol on a flat brass cap with fracture surface up. The cap was rapidly plunged into liquid nitrogen and transferred to a freeze- etch unit. The sample was etched for 3 min at -95°C to remove any condensed water vapor and then cooled to -150°C for platinum/carbon evaporation.

Single particle dynamics of supercooled water and the kinetic glass transition

1998 ◽  
Vol 08 (PR6) ◽  
pp. Pr6-109-Pr6-113
Author(s):  
P. Gallo ◽  
F. Sciortino ◽  
P. Tartaglia ◽  
S.-H. Chen
Keyword(s):  
Glass Transition ◽  
Single Particle ◽  
Supercooled Water ◽  
Particle Dynamics
Sign in / Sign up

Export Citation Format

Share Document