Experimental visualization and characteristics of bubble nucleation during rapid decompression of supercritical and subcooled carbon dioxide

2021 ◽  
pp. 104569
Author(s):  
Declan Quinn ◽  
Drew Stannard ◽  
Jeff Edwards ◽  
Kamal K. Botros ◽  
Craig Johansen
Keyword(s):  
Carbon Dioxide ◽  
Bubble Nucleation ◽  
Rapid Decompression

Bubbles and element clusters in rock melts: A chicken and egg problem

2021 ◽  
Author(s):  
Renelle Dubosq ◽  
Pia Pleše ◽  
Brian Langelier ◽  
Baptiste Gault ◽  
David Schneider
Keyword(s):  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Growth Dynamics ◽  
Gas Bubbles ◽  
Atom Probe ◽  
Bubble Nucleation ◽  
Interface Element ◽  
Rich Cluster ◽  
Heterogeneous Distribution ◽  
Rapid Decompression

<p>The nucleation and growth dynamics of gas bubbles and crystals play a vital function in determining the eruptive behaviour of a magma. Their rate and relative timing, among other factors, are controlled by the magma’s ascent rate. Investigating the kinetics of decompression-induced degassing and crystallization processes can thus give us insight into the rheology of magmas. For example, the rapid decompression of magmas inhibits microlite crystallization and bubble nucleation during ascent leading to crystallization and degassing at shallow levels. This results in a drastic increase in viscosity and an over pressured system, which can lead to violent eruptions. Although many experiments and numerical simulations of magma decompression have been carried out, nascent and initial bubble nucleation remain poorly understood. It is widely accepted that there are two ways bubbles can nucleate within a melt: heterogeneous (on a pre-existing surface) and homogeneous nucleation (within the melt), where homogeneous nucleation requires a higher volatile supersaturation. It has since been tentatively suggested that homogeneous nucleation is simply a variety of heterogeneous nucleation where nucleation occurs on the surface of submicroscopic crystals. However, evidence of these crystals is equivocal. Thus, we have combined novel 2D and 3D structural and chemical microscopy techniques including scanning transmission electron microscopy (STEM), electron energy-loss spectroscopy (EELS) mapping, and atom probe tomography (APT) to investigate the presence of sub-nanometer scale chemical heterogeneities in the vicinity of gas bubbles within an experimental andesitic melt. The combined STEM and EELS data reveal a heterogeneous distribution of bubbles within the melt ranging between 20-100 nm in diameter, some of which have Fe and/or Ca element clusters at the bubble-melt interface. Element clusters enriched in Fe, Ca, and Na are also observed heterogeneously distributed within the melt. The reconstructed APT data reveals bubbles as low ionic density regions overlain by a Na-, Ca-, and K-rich cluster and heterogeneously distributed Fe clusters within the bulk of the melt. Based on these observations, our data demonstrate the existence of nano-scale chemical heterogeneities within the melt and at the bubble-melt interface of bubbles that were previously interpreted to be nucleated homogeneously within the melt, therefore contributing to the proposed hypothesis that homogeneous nucleation could in fact be a variety of heterogeneous nucleation. These results highlight the need to redefine homogeneous nucleation and revisit whether bubbles or crystals occur first within volcanic melts. </p>

Experimental Study on Bubble Nucleation in the Oscillating Pressure Field

1978 ◽  
Vol 100 (3) ◽  
pp. 460-465 ◽  
Author(s):  
K. Hijikata ◽  
Y. Mori ◽  
T. Nagatani
Keyword(s):  
Carbon Dioxide ◽  
Characteristic Time ◽  
Pressure Field ◽  
Pressure Oscillation ◽  
Oscillation Period ◽  
Bubble Nucleation ◽  
Dissolved Carbon ◽  
Dissolved Carbon Dioxide ◽  
Order Of Magnitude ◽  
Superheat Limit

In bubble nucleation under the oscillating pressure field, when the oscillation period τ is of the same order of magnitude as the characteristic time τn of bubble nucleation, it is expected that the distribution of radius of bubble embryo in liquid will be largely affected by the pressure oscillation and the degree of superheat limit may change. In order to clarify this point, superheat limits of homogeneous nucleation under the oscillating pressure field generated by ultrasonic oscillators are measured for propane with and without dissolved carbon dioxide by the floating droplet method. From the experimental results it is found that when τ > τn the measured superheat limit agrees with that calculated by the conventional theory where the quasi-steady state is assumed, but the bubble nucleation occurs at temperature lower than that preducted by the theory when τ nearly equals τn. It is also found that the characteristic time of bubble nucleation is changed by the amount of dissolved carbon dioxide.

A strategy for in-flight measurements of physiology of pilots of high-performance fighter aircraft

2013 ◽  
Vol 115 (1) ◽  
pp. 145-149 ◽  
Author(s):  
John B. West
Keyword(s):  
Carbon Dioxide ◽  
Cognitive Impairment ◽  
Gas Exchange ◽  
Flow Rate ◽  
High Performance ◽  
Inspiratory Flow ◽  
Inspiratory Flow Rate ◽  
Fighter Aircraft ◽  
Rapid Decompression ◽  
Flight Measurements

Some pilots flying modern high-performance fighter aircraft develop “hypoxia-like” incidents characterized by short periods of confusion and cognitive impairment. The problem is serious and recently led to the grounding of a fleet of aircraft. Extensive discussions of the incidents have taken place but some people believe that there is inadequate data to determine the cause. There is a tremendous disconnect between what is known about the function of the aircraft and the function of the pilot. This paper describes a plan for measuring the inspired and expired Po2 and Pco2 in the pilot's mask, the inspiratory flow rate, and pressure in the mask. A critically important requirement is that the interference with the function of the pilot is minimal. Although extensive physiological measurements were previously made on pilots in ground-based experiments such as rapid decompression in an altitude chamber and increased acceleration on a centrifuge, in-flight measurements of gas exchange have not been possible until now primarily because of the lack of suitable equipment. The present paper shows how the recent availability of small, rapidly responding oxygen and carbon dioxide analyzers make sophisticated in-flight measurements feasible. The added information has the potential of greatly improving our knowledge of pilot physiology, which could lead to an explanation for the incidents.

scholarly journals Elevated Environmental Carbon Dioxide Exposure Confounding Physiologic Events in Aviators?

2019 ◽  
Vol 184 (11-12) ◽  
pp. e863-e867
Author(s):  
Chad T Andicochea ◽  
Matthew E Henriques ◽  
Joel Fulkerson ◽  
Susan Jay ◽  
Howard Chen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Elevated Co2 ◽  
Decompression Sickness ◽  
Safety Concern ◽  
Case Series ◽  
Environmental Data ◽  
Type Ii ◽  
Co2 Levels ◽  
Rapid Decompression

Abstract Introduction Physiological events (PEs) are a growing problem for US military aviation with detrimental risks to safety and mission readiness. Seeking causative factors is, therefore, of high importance. There is no evidence to date associating carbon dioxide (CO2) pre-flight exposure and decompression sickness (DCS) in aviators. Materials and Methods This study is a case series of six aviators with PE after being exposed to a rapid decompression event (RDE) with symptoms consistent with type II DCS. The analysis includes retrospective review of flight and environmental data to further assess a possible link between CO2 levels and altitude physiologic events (PEs). IRB approval was obtained for this study. Results This case series presents six aviators with PE after being exposed to a rapid decompression event (RDE) with symptoms consistent with type II DCS. Another three aviators were also exposed to a RDE, but remained asymptomatic. All events involved tactical jet aircraft flying at an average of 35,600’ Mean Sea Level (MSL) when a RDE occurred, Retrospective reviews led to the discovery that the affected individuals were exposed, pre-flight, to poor indoor air quality demonstrated by elevated levels of measured CO2. Conclusion PEs are a growing safety concern for the aviation community in the military. As such, increasing measures are taken to ensure safety of flight and completion of the mission. To date, there is no correlation of CO2 exposure and altitude DCS. While elevated CO2 levels cannot be conclusively implicated as causative, this case series suggests a potential role of CO2 in altitude DCS through CO2 direct involvement with emboli gas composition, as well as pro-inflammatory cascade. Aviators exposed to elevated CO2 in poorly ventilated rooms developed PE symptoms consistent with DCS, while at the same command, aviators that were exposed to a well ventilated room did not. This report is far from an answer, but does demonstrate an interesting case series that draws some questions about CO2’s role in these aviator’s DCS experience. Other explanations are plausible, including the accurate diagnosis of DCS, health variables amongst the aviators, and differences in aircraft and On-Board Oxygen Generation Systems (OBOGS). For a better understanding, the role of environmental CO2 and pre-flight exposure as a risk of DCS should be reviewed.

scholarly journals Human physiology under high pressure: I. Effects of Nitrogen, Carbon dioxide, and Cold

1941 ◽  
Vol 41 (3) ◽  
pp. 225-249 ◽  
Author(s):  
E. M. Case ◽  
J. B. S. Haldane
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Partial Pressure ◽  
Atmospheric Pressure ◽  
Good Deal ◽  
Considerable Effect ◽  
Manual Dexterity ◽  
Human Beings ◽  
Partial Pressures ◽  
Rapid Decompression

We confirm the finding of Behnke,et al.(1935) that air at 8·6 atm. pressure has a somewhat intoxicating effect on human beings, and that this effect is due to nitrogen. The nitrogen effect reaches its maximum after about 3 min. There was no reduction of manual dexterity in the test used by us, but a considerable effect on performance of arithmetic, and on most practical activities. At 10 atm. these effects were somewhat enhanced, and manual dexterity was lowered in some cases. When helium or hydrogen was substituted for nitrogen there was no intoxication.3–4% of carbon dioxide at atmospheric pressure caused no deterioration in manual or arithmetical skill, and in the two subjects tested, 6% of carbon dioxide caused no deterioration.When air containing about 0·4% of carbon dioxide, and therefore with a partial pressure of about 4%, was breathed at 10 atm., there was a marked deterioration in manual dexterity, and a good deal of confusion. When breathing carbon dioxide at partial pressures of 6·6–9·7% at 10. atm., eight subjects lost consciousness in 1–5 min., but some could tolerate partial pressures of over 8% for 5 min. or more. With half an hour's exposure to a partial pressure of 6–7% of carbon dioxide, one subject lost consciousness after 7 min. at 10 atm. pressure, and another nearly did so.We consider that the percentage of carbon dioxide in air at 10 atm. pressure should be kept below 0·3%. Exposure to high partial pressures of carbon dioxide at 10 atm. does not increase the liability to ‘bends’ or other symptoms due to rapid decompression.Immersion in water below 40° F. did not enhance the effects of high-pressure air, or of carbon dioxide at atmospheric pressure, but somewhat enhanced those of high pressure and carbon dioxide together.In certain breathing apparatus the resistance became so great at 10 atm. as to be intolerable.Few subjects experienced serious trouble during compression, or during or after decompression. But one developed a unilateral pneumothorax.

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