On Measuring Bubble Nucleation Temperature of Water/Methanol Mixtures Using Ink-Jet Printer Technology

2001 ◽  
Author(s):  
C. T. Avedisian ◽  
W. S. Osborne ◽  
F. D. McLeod
Keyword(s):  
Power Input ◽  
Bubble Nucleation ◽  
Methanol Concentration ◽  
Nucleation Temperature ◽  
Instrumentation Amplifier ◽  
Heating Rates ◽  
Heater Element ◽  
Ink Jet ◽  
Evolution Of Resistance ◽  
The Difference

Abstract The bubble nucleation temperature of water/methanol mixtures is measured using the fast transient process of thermal ink-jet printer technology. The heater element is placed in a dynamic bridge circuit coupled with an instrumentation amplifier to measure the change in resistance of the heater as a programmed voltage is applied across the bridge. An inflection point in the evolution of resistance signals bubble nucleation. A separate calibration relates resistance to average heater temperature. The results show that the nucleation temperature increases as the power input to the bridge increases for a given concentration. The heating rates are extremely high, in some cases reaching over a quarter billion degrees per second. As methanol concentration increases, the nucleation temperature decreases. It was difficult to measure the nucleation temperature at high methanol dilution because the difference between liquid and vapor thermal conductivity decreases as methanol concentration increases for a given temperature. The nucleation temperatures are successfully correlated with a generalized corresponding states theory.

An Experimental Study of Microscopic Explosive Boiling Induced by Pulsed-Laser Irradiation

2002 ◽  
Author(s):  
Xiulan Huai ◽  
Zhaoyi Dong ◽  
Dengying Liu ◽  
G.-X. Wang
Keyword(s):  
Experimental Study ◽  
Heating Rate ◽  
Laser Heating ◽  
High Speed ◽  
Quartz Substrate ◽  
Pulsed Laser ◽  
Bubble Nucleation ◽  
Nucleation Temperature ◽  
Heating Rates ◽  
Explosive Boiling

Microscopic explosive boiling due to rapid heating has found many applications in modern technologies such as thermal ink jet printing, laser cleaning, and laser surgery. It is a nonequilibrium process involving an extremely high liquid superheating. This paper presents an experimental study of such an explosive vaporization process induced by firing a microsecond pulsed laser beam on a thin Pt film deposited on a quartz substrate. The temperature variation of the Pt film is measured by recording the electric resistance of the film during laser heating and subsequent cooling. A high-speed photographic technique is employed to visualize the bubble formation and the explosive evaporation process. Explosive boiling experiments have been carried out in either a pool of acetone liquid or a thin acetone film covering the Pt film. The heating rate achieved ranges from 8.0×106 K/s to 9.0×107 K/s. Violent explosive boiling was observed in the case of a liquid film and the vapor bubbles together with liquid droplets were expelled from the Pt film. While in the case of a liquid pool, only a large cluster of bubbles was formed on the Pt film during laser heating. A close examination of the temperature curves reveals a sudden reduction in the heating rate during laser heating, and an apparent bubble nucleation temperature can be defined. Experimental data show that this apparent bubble nucleation temperature is a strong function of the heating rate. It is close to the equilibrium boiling point at low heating rates while approaches the homogeneous nucleation temperature at high heating rates.

Bubble Nucleation on Micro Line Heaters

2003 ◽  
Vol 125 (4) ◽  
pp. 687-692 ◽  
Author(s):  
Jung-Yeop Lee ◽  
Hong-Chul Park ◽  
Jung-Yeul Jung ◽  
Ho-Young Kwak
Keyword(s):  
Contact Angle ◽  
Free Surface ◽  
Cluster Model ◽  
Bubble Nucleation ◽  
Nucleation Temperature ◽  
Molecular Cluster ◽  
Resistance Characteristic ◽  
Nucleation Process ◽  
Superheat Limit ◽  
Current Resistance

Nucleation temperatures on micro line heaters were measured precisely by obtaining the I-R (current-resistance) characteristic curves of the heaters. The bubble nucleation temperature on the heater with 3 μm width is higher than the superheat limit, while the temperature on the heater with broader width of 5 μm is considerably less than the superheat limit. The nucleation temperatures were also estimated by using the molecular cluster model for bubble nucleation on the cavity free surface with effect of contact angle. The bubble nucleation process was observed by microscope/35 mm camera unit with a flash light of μs duration.

Pressureless Co-Sintering of Al2O/ZrO2 Multilayers and Bilayers

1996 ◽  
Vol 434 ◽  
Author(s):  
Peter Z. Cai ◽  
David J. Green ◽  
Gary L. Messing
Keyword(s):  
Thermal Expansion ◽  
Cyclic Loading ◽  
Microscopic Observation ◽  
Surface Defects ◽  
Tape Casting ◽  
Thermal Expansion Mismatch ◽  
Heating Rates ◽  
The Difference ◽  
Extent Of Damage ◽  
Transverse Damage

AbstractVarious types of damage were observed in pressureless-sintered Al2O3/ZrO2 symmetric laminates (multilayers) and asymmetric laminates (bilayers) fabricated by tape casting and lamination. These defects included channel defects in ZrO2-containing layers, Al2O3 surface defects parallel to the layers, decohesion between the layers, and transverse damage within the Al2O3 layer in the bilayers. Detailed microscopic observation attributed the defects to a combined effect of mismatch in both sintering rate and thermal expansion coefficient between the layers. Crack-like defects were formed in the early stages of densification, and these defects acted as pre-existing flaws for thermal expansion mismatch cracks. Curling of the bilayers during sintering was monitored and the measured rate of curvature change, along with the layer viscosities obtained by cyclic loading dilatometry, was used to estimate the sintering mismatch stresses. The extent of damage could be reduced or even eliminated by decreasing the difference in layer sintering rate. This was accomplished by reducing the heating rates or by adding Al2O3 in the ZrO2 layers.

Molecular Dynamics Simulation of Homogeneous and Heterogeneous Thermal Bubble Nucleation

2011 ◽  
Author(s):  
Min Chen ◽  
Yunfei Chen ◽  
Juekuan Yang ◽  
Yandong Gao ◽  
Deyu Li
Keyword(s):  
Molecular Dynamics ◽  
Heterogeneous Systems ◽  
Liquid Argon ◽  
Bubble Nucleation ◽  
Dynamics Simulation ◽  
Nucleation Temperature ◽  
The Common ◽  
Solid Walls ◽  
Common Understanding ◽  
Superheat Limit

Thermal bubble nucleation was studied using molecular dynamics for both homogeneous and heterogeneous systems using isothermal-isobaric (NPT) and isothermal-isostress (NPzzT) ensembles. Simulation results indicate that homogeneous thermal bubble nucleation is induced from cavities occurring spontaneously in the liquid when the temperature exceeds the superheat limit. In contrast to published results using NVE and NVT ensembles, no stable nanoscale bubble exists in NPT ensembles, but instead, the whole system changes into vapor phase. For a heterogeneous system composed of a nanochannel with an initial distance of 3.49 nm between the two solid plates, it is found that if the liquid-solid interaction is equal to or stronger than that between liquid argon atoms, the bubble nucleation temperature of the confined liquid argon can be higher than the corresponding homogeneous nucleation temperature, because of the more ordered arrangement of atoms within two solid walls nanometers apart. This observation is in contradiction to the common understanding that homogeneous bubble nucleation temperature sets an upper limit for thermal phase change under a given pressure. Compared to the system where the liquid-solid interaction is the same as that between liquid argon atoms, the system with reduced liquid-solid interaction possesses a significantly reduced bubble nucleation temperature, while the system with enhanced liquid-solid interaction only has a marginally increased bubble nucleation temperature.

scholarly journals Atomic hydrogen III—The energy efficiency of atom production in a glow discharge

1937 ◽  
Vol 163 (914) ◽  
pp. 424-454 ◽  
Keyword(s):  
Glow Discharge ◽  
Closed System ◽  
Atomic Hydrogen ◽  
Empirical Relation ◽  
Power Input ◽  
Degree Of Dissociation ◽  
Recombination Processes ◽  
Dark Space ◽  
The Difference ◽  
Three Body

There seems to have been a tendency amongst workers on the use of the glow discharge as a source of atomic hydrogen to regard the current or power as determining the degree of dissociation of the gas, i. e. the equi­librium H 2 ⇌2H. It is clear, however, that the discharge itself determines only the rate of production of atoms, whereas the degree of dissociation depends also on the rate of removal of atoms by pumping and by recombina­tion processes which are independent of the discharge. The two homogeneous recombination processes are those resulting from three-body collisions be­tween three atoms and between two atoms and a molecule; in addition, there is a heterogeneously catalysed reaction in which the walls of the tube act as the energy acceptor. Attempts to connect electrical conditions with degree of dissociation have been made by Crew and Hulburt (1927) and by Wrede (1929), but the above remarks show that only empirical relationships can be hoped for. In Crew and Hulburt’s experiments, the degree of dissociation was estimated by measuring the change of pressure in a closed system on passing a discharge. A correction for temperature was applied, which was based on the erroneous idea that the rise of temperature due to discharge in helium is about the same as that in hydrogen at the same pressure and power input. The method of determining the pressure depended on an empirical relation between pressure and the length of the cathode dark space in an auxiliary discharge connected to the main system ; but since the cathode dark space has not a sharply defined boundary, and the degree of dissociation is calculated from the difference of two pressures measured in this way, considerable error is possible. Furthermore, in a closed system, the rate of production of atoms is equal to the rate of recombination; and since these workers relied on a water-on-glass film to inhibit heterogeneous recombination, and as the power input was 200-1000 W, the catalytic activity of the walls must have been very variable and large (Part II). Crew and Hulburt’s curves con­necting degree of dissociation with pressure and power input cannot, there­fore, be credited with quantitative significance.

Vapour-bubble nucleation and dynamics in turbulent Rayleigh–Bénard convection

2016 ◽  
Vol 795 ◽  
pp. 60-95 ◽  
Author(s):  
Daniela Narezo Guzman ◽  
Tomasz Frączek ◽  
Christopher Reetz ◽  
Chao Sun ◽  
Detlef Lohse ◽  
...  
Keyword(s):  
Large Scale ◽  
Bubbly Flow ◽  
Central Area ◽  
Bubble Nucleation ◽  
Bottom Plate ◽  
Small Range ◽  
Plate Temperature ◽  
Sample Height ◽  
The Difference ◽  
Rayleigh Benard

Vapour bubbles nucleating at micro-cavities etched into the silicon bottom plate of a cylindrical Rayleigh–Bénard sample (diameter $D=8.8$  cm, aspect ratio ${\it\Gamma}\equiv D/L\simeq 1.00$ where $L$ is the sample height) were visualized from the top and from the side. A triangular array of cylindrical micro-cavities (with a diameter of $30~{\rm\mu}\text{m}$ and a depth of $100~{\rm\mu}\text{m}$) covered a circular centred area (diameter of 2.5 cm) of the bottom plate. Heat was applied to the sample only over this central area while cooling was over the entire top-plate area. Bubble sizes and frequencies of departure from the bottom plate are reported for a range of bottom-plate superheats $T_{b}-T_{on}$ ($T_{b}$ is the bottom-plate temperature, $T_{on}$ is the onset temperature of bubble nucleation) from 3 to 12 K for three different cavity separations. The difference $T_{b}-T_{t}\simeq 16$  K between $T_{b}$ and the top plate temperature $T_{t}$ was kept fixed while the mean temperature $T_{m}=(T_{b}+T_{t})/2$ was varied, leading to a small range of the Rayleigh number $Ra$ from $1.4\times 10^{10}$ to $2.0\times 10^{10}$. The time between bubble departures from a given cavity decreased exponentially with increasing superheat and was independent of cavity separation. The contribution of the bubble latent heat to the total enhancement of heat transferred due to bubble nucleation was found to increase with superheat, reaching up to 25 %. The bubbly flow was examined in greater detail for a superheat of 10 K and $Ra\simeq 1.9\times 10^{10}$. The condensation and/or dissolution rates of departed bubbles revealed two regimes: the initial rate was influenced by steep thermal gradients across the thermal boundary layer near the plate and was two orders of magnitude larger than the final condensation and/or dissolution rate that prevailed once the rising bubbles were in the colder bulk flow of nearly uniform temperature. The dynamics of thermal plumes was studied qualitatively in the presence and absence of nucleating bubbles. It was found that bubbles enhanced the plume velocity by a factor of four or so and drove a large-scale circulation (LSC). Nonetheless, even in the presence of bubbles the plumes and LSC had a characteristic velocity which was smaller by a factor of five or so than the bubble-rise velocity in the bulk. In the absence of bubbles there was strongly turbulent convection but no LSC, and plumes on average rose vertically.

The effect of sampling rate on interpretation of the temporal characteristics of radiative and convective heating in wildland flames

2013 ◽  
Vol 22 (2) ◽  
pp. 168 ◽  
Author(s):  
David Frankman ◽  
Brent W. Webb ◽  
Bret W. Butler ◽  
Daniel Jimenez ◽  
Michael Harrington
Keyword(s):  
Sampling Rate ◽  
Sampling Frequency ◽  
Heat Fluxes ◽  
Radiative Heating ◽  
Convective Heating ◽  
Moving Window ◽  
Prescribed Burn ◽  
Heating Rates ◽  
Time Resolved ◽  
The Difference

Time-resolved radiative and convective heating measurements were collected on a prescribed burn in coniferous fuels at a sampling frequency of 500 Hz. Evaluation of the data in the time and frequency domain indicate that this sampling rate was sufficient to capture the temporal fluctuations of radiative and convective heating. The convective heating signal contained significantly larger fluctuations in magnitude and frequency than did the radiative heating signal. The data were artificially down-sampled to 100, 50, 10, 5 and 1 Hz to explore the effect of sampling rate on peak heat fluxes, time-averaged heating and integrated heating. Results show that for sampling rates less than 5 Hz the difference between measured and actual peak radiative heating rates can be as great as 24%, and is on the order of 80% for 1-Hz sampling rates. Convective heating showed degradation in the signal for sampling rates less than 100 Hz. Heating rates averaged over a 2-s moving window, as well as integrated radiative and convective heating were insensitive to sampling rate across all ranges explored. The data suggest that peak radiative and convective heating magnitudes cannot be fully temporally resolved for sampling frequencies lower than 20 and 200 Hz.

scholarly journals Southern Ocean Response to Relative Velocity Wind Stress Forcing

2010 ◽  
Vol 40 (2) ◽  
pp. 326-339 ◽  
Author(s):  
David K. Hutchinson ◽  
Andrew Mc C. Hogg ◽  
Jeffrey R. Blundell
Keyword(s):  
Southern Ocean ◽  
Wind Stress ◽  
Relative Velocity ◽  
Power Input ◽  
Quadratic Drag ◽  
The Difference ◽  
Atmospheric Mixed Layer ◽  
Circumpolar Current ◽  
Quasigeostrophic Model ◽  
Drag Law

Abstract An eddy-resolving quasigeostrophic model of the Southern Ocean coupled to a dynamic atmospheric mixed layer is used to compare the performance of two different wind stress parameterization schemes. The first is the standard quadratic drag law, based on atmospheric velocity alone, whereas the second (more exact) formulation is based on the difference between ocean and atmosphere velocities. The two different schemes give very similar magnitudes of mean stress; however, the relative velocity scheme has substantially lower power input, resulting in a weaker eddy field, and consequently, greater circumpolar transport. These results are explored in terms of the existing theories of the Antarctic Circumpolar Current (including eddy saturation and eddy damping) and the implications for modeling the Southern Ocean are discussed.

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