scholarly journals Experiments with CO<sub>2</sub>-in-air reference gases in high-pressure aluminum cylinders

2018 ◽  
Vol 11 (10) ◽  
pp. 5565-5586 ◽  
Author(s):  
Michael F. Schibig ◽  
Duane Kitzis ◽  
Pieter P. Tans
Keyword(s):  
High Pressure ◽  
Large Scale ◽  
High Pressures ◽  
Co2 Enrichment ◽  
Low Flow ◽  
Cylinder Wall ◽  
Practical Applications ◽  
Sources And Sinks ◽  
Carbon Dioxide Co2 ◽  
Adsorption Desorption

Abstract. Long-term monitoring of carbon dioxide (CO2) in the atmosphere is key for a better understanding of the processes involved in the carbon cycle that have a major impact on further climate change. Keeping track of large-scale emissions and removals (sources and sinks) of CO2 requires very accurate measurements. They all have to be calibrated very carefully and have to be traceable to a common scale, the World Meteorological Organization (WMO) CO2 X2007 scale, which is maintained by the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL) in Boulder, CO, USA. The international WMO GAW (Global Atmosphere Watch) program sets as compatibility goals for the required agreement between different methods and laboratories ±0.1 µmol mol−1 for the Northern Hemisphere and ±0.05 µmol mol−1 for the Southern Hemisphere. The reference gas mixtures used to pass down and distribute the scale are stored in high-pressure aluminum cylinders. It is crucial that the standards remain stable during their entire time of use. In this study the tested vertically positioned aluminum cylinders showed similar CO2 enrichment during low-flow conditions (0.3 L min−1), which are similar to flows often used for calibration gases in practical applications. The average CO2 enrichment was 0.090±0.009 µmol mol−1 as the cylinder was emptied from about 150 to 1 bar above atmosphere. However, it is important to note that the enrichment is not linear but follows Langmuir's adsorption–desorption model, where the CO2 enrichment is almost negligible at high pressures but much more pronounced at low pressures. When decanted at a higher rate of 5.0 L min−1 the enrichment becomes 0.22±0.05 µmol mol−1 for the same pressure drop. The higher enrichment is related to thermal diffusion and fractionation effects in the cylinder, which were also dependent on the cylinder's orientation and could even turn negative. However, the low amount of CO2 adsorbed on the cylinder wall and the fact that the main increase happens at low pressure lead to the conclusion that aluminum cylinders are suitable to store ambient CO2-in-dry-air mixtures provided they are not used below 20 bar. In cases where they are used in high-flow experiments that involve significant cylinder temperature changes, special attention has to be paid to possible fractionation effects.

scholarly journals Experiments with CO<sub>2</sub> -in-air reference gases in high-pressure aluminum cylinders

2018 ◽  
Author(s):  
Michael F. Schibig ◽  
Duane Kitzis ◽  
Pieter P. Tans
Keyword(s):  
High Pressure ◽  
Large Scale ◽  
Co2 Enrichment ◽  
Low Flow ◽  
Cylinder Wall ◽  
Temperature Changes ◽  
Sources And Sinks ◽  
Carbon Dioxide Co2 ◽  
Adsorption Desorption

Abstract. Long term monitoring of carbon dioxide (CO2) in the atmosphere is key for a better understanding of the processes involved in the carbon cycle that have a major impact on further climate change. Keeping track of large-scale emissions and removals (“sources and sinks”) of CO2 requires very accurate measurements. They all have to be calibrated very carefully and have to be traceable to a common scale, the WMO CO2 X2007 scale, which is maintained by NOAA/ESRL (Oceanic and Atmospheric Administration/Earth System Research Laboratory) in Boulder, CO, USA. The international WMO/GAW (World Meteorological Organization/Global Atmosphere Watch) program sets as compatibility goals for the required agreement between different methods and laboratories ±0.1 μmol mol−1 for the northern hemisphere and ±0.05 μmol mol−1 for the southern hemisphere. The reference gas mixtures used to pass down and distribute the scale are stored in high pressure aluminum cylinders. It is crucial that the standards remain stable during their entire time of use. In this study we found that during low flow conditions (0.3 l min−1) the tested vertically positioned aluminum cylinders always showed similar CO2 enrichment of 0.090 ±  0.009 μmol mol−1 as the cylinder was emptied from about 140 to 1 bar above atmosphere, following Langmuir’s adsorption/desorption model. When decanted at a higher rate of 5.0 l min−1 the enrichment becomes 0.22 ± 0.05 μmol mol−1 for the same pressure drop. The higher enrichment is related to thermal diffusion and fractionation effects in the cylinder, which were also dependent on the cylinder’s orientation and could even turn negative. However, the low amount of CO2 adsorbed on the cylinder wall as well as the fact that the main increase happens at low pressure lead to the conclusion that aluminum cylinders are suitable to store ambient CO2-in-dry-air mixtures provided they are not used below 20 bar. In case they are used in high flow experiments that involve significant cylinder temperature changes, special attention has to be paid to possible fractionation effects.

Hypopharyngeal Pressure in Brass Musicians

2003 ◽  
Vol 18 (4) ◽  
pp. 153-155
Author(s):  
C Richard Stasney ◽  
Mary Es Beaver ◽  
Margarita Rodriguez
Keyword(s):  
High Pressure ◽  
Health Risks ◽  
High Pressures ◽  
High Flow ◽  
French Horn ◽  
Low Flow ◽  
Cross Sectional ◽  
Brass Instruments ◽  
Pharyngeal Pressure ◽  
Is Development

Brass instrument players are exposed to unique health risks due to increased pharyngeal pressures necessary for performance. One such risk is development of laryngoceles, or “blowout” of the larynx. This cross-sectional observational study was performed to determine the pressure required to play different frequencies in a variety of brass instruments. The hypothesis tested was that enharmonic frequencies require the same pharyngeal pressure regardless of the instrument. The brass instruments tested were high-pressure, low-flow instruments (trumpet or French horn) or low-pressure, high-flow instruments (tuba or trombone). We were not able to substantiate Jacobs’ theory that enharmonic frequencies resulted in equal pressures regardless of instrument, but we did elicit some high pressures in the hypopharynx when playing the trumpet or horn at higher frequencies.

High Pressure Fan Design for Biogas Plants

2009 ◽  
Author(s):  
Philipp Epple ◽  
Mihai Miclea ◽  
Harald Schmidt ◽  
Antonio Delgado ◽  
Hans Russwurm
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Thermal Power ◽  
Flow Analysis ◽  
Single Stage ◽  
Low Flow ◽  
Operating Point ◽  
Flow Rates ◽  
New Class ◽  
Biogas Plants

High pressure fans for thermal power generation stations, especially biogas plants, usually operate in a spiral casing at high pressures of about p = 12.000–15.000 Pa and low flow rates of around Q = 100–600 m3/s. The motor drive has a constant speed of 3.000 l/min. This corresponds to specific speeds of nq = 3–6 min−1, which is already beyond the conventional range of single stage radial machines. Nowadays these fans for biogas plants usually operate at higher flow rates than specified or are multiple stage radial fans. Therefore a new class of radial impellers has been developed. These single stage impellers have a unique high pressure at a low flow rate operating point. In this work several impellers of this new class have been designed and validated with a commercial Navier-Stokes solver (ANSYS CFX). The design process is described in detail. It is based on a new extended analytical and numerical design method. It is shown that the prescribed unusual operating point can be achieved with single stage radial impellers. An in detail flow analysis is given showing the fundamental flow physics of these impellers.

scholarly journals Determination of basal hydraulic systems based on subglacial high-pressure pump experiments

2005 ◽  
Vol 40 ◽  
pp. 37-42 ◽  
Author(s):  
Gaute Lappegard ◽  
Jack Kohler
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Water Pressure ◽  
Drainage System ◽  
Load Cell ◽  
Low Flow ◽  
Hydraulic Systems ◽  
High Pressure Pump ◽  
Pressure Transducers ◽  
Fast Flow

AbstractWe have conducted short-term pump experiments with pump pressures exceeding ice overburden to study the seasonality of the subglacial hydraulic system of Engabreen, Norway. Data were collected from load cells installed flush with the ice–bedrock interface and pressure transducers installed in boreholes leading from bedrock tunnels underneath the glacier to the ice–bedrock interface. The water-pressure recordings, seen in relation with the load-cell record, show the existence of hydraulically connected vs unconnected bed areas. Monitored boreholes have been used to inject water at high pressures. Each experiment led to the growth of a high-pressure water cavity whose spatial extent could be inferred from load-cell and pressure transducer records. Post-pump pressures were low after summer pump tests and close to ice-overburden level after winter pump experiments. We conclude that drainage takes place in a fast-flow, low-pressure, channel-based drainage system during summer, and a low-flow, high-pressure, linked-cavity drainage system during winter.

scholarly journals Large-Scale Transposon Mutagenesis of Photobacterium profundum SS9 Reveals New Genetic Loci Important for Growth at Low Temperature and High Pressure

2007 ◽  
Vol 190 (5) ◽  
pp. 1699-1709 ◽  
Author(s):  
Federico M. Lauro ◽  
Khiem Tran ◽  
Alessandro Vezzi ◽  
Nicola Vitulo ◽  
Giorgio Valle ◽  
...  
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Deep Sea ◽  
Large Scale ◽  
High Pressures ◽  
Cell Envelope ◽  
Transposon Mutagenesis ◽  
Chromosomal Structure ◽  
And Function ◽  
Photobacterium Profundum

ABSTRACT Microorganisms adapted to piezopsychrophilic growth dominate the majority of the biosphere that is at relatively constant low temperatures and high pressures, but the genetic bases for the adaptations are largely unknown. Here we report the use of transposon mutagenesis with the deep-sea bacterium Photobacterium profundum strain SS9 to isolate dozens of mutant strains whose growth is impaired at low temperature and/or whose growth is altered as a function of hydrostatic pressure. In many cases the gene mutation-growth phenotype relationship was verified by complementation analysis. The largest fraction of loci associated with temperature sensitivity were involved in the biosynthesis of the cell envelope, in particular the biosynthesis of extracellular polysaccharide. The largest fraction of loci associated with pressure sensitivity were involved in chromosomal structure and function. Genes for ribosome assembly and function were found to be important for both low-temperature and high-pressure growth. Likewise, both adaptation to temperature and adaptation to pressure were affected by mutations in a number of sensory and regulatory loci, suggesting the importance of signal transduction mechanisms in adaptation to either physical parameter. These analyses were the first global analyses of genes conditionally required for low-temperature or high-pressure growth in a deep-sea microorganism.

Computational Modeling of Natural Gas Injection in a Large Bore Engine

2004 ◽  
Vol 126 (3) ◽  
pp. 656-664 ◽  
Author(s):  
Gi-Heon Kim ◽  
Allan Kirkpatrick ◽  
Charles Mitchell
Keyword(s):  
High Pressure ◽  
Computational Modeling ◽  
Gas Flow ◽  
High Pressures ◽  
Volume Fraction ◽  
Gas Injection ◽  
Cylinder Wall ◽  
Poppet Valve ◽  
Injection Process ◽  
Planar Laser

The topic of this paper is the computational modeling of gas injection through various poppet valve geometries in a large bore engine. The objective of the paper is to contribute to a better understanding of the significance of the poppet valve and the piston top in controlling the mixing of the injected fuel with the air in the cylinder. In this paper, the flow past the poppet valve into the engine cylinder is computed for both a low (4 bar) and a high pressure (35 bar) injection process using unshrouded and shrouded valves. Experiments using PLIF (planar laser induced fluorescence) are used to visualize the actual fluid flow for the valve geometries considered. The results indicate that for low injection pressures the gas flow around a typical poppet valve collapses to the axis of symmetry of the valve downstream of the poppet. At high pressure, the gas flow from this simple poppet valve does not collapse, but rather expands outward and flows along the cylinder wall. At high pressures, addition of a shroud around the poppet valve was effective in directing the supersonic flow toward the center of the cylinder. Additional computations with a moving piston show that at top dead center, the flammable volume fraction and turbulence intensity with high pressure shrouded injection are larger than for low pressure injection.

Thermodynamic Analysis of a Highly Pressurized CO2 Cycle for Renewable Energy Applications

2020 ◽  
Author(s):  
Geoffrey R. Kemmerer ◽  
Thomas Gross ◽  
Kevin R. Anderson
Keyword(s):  
High Pressure ◽  
Renewable Energy ◽  
Alternative Energy ◽  
High Pressures ◽  
Maximum Energy ◽  
Coefficient Of Performance ◽  
Modeling And Analysis ◽  
Energy Applications ◽  
Turbo Expander ◽  
Carbon Dioxide Co2

Abstract Refrigerated gases have been used to store energy with limited success. This paper presents the results of an exploratory study of how the behavior of fluids compressed to high pressures can be used to increase the efficiency of refrigeration cycles and one possible application for renewable energy. This research presents the results of thermodynamic modeling and analysis of a novel Carbon Dioxide (CO2) cycle to be used for alternative energy production. The thermodynamic computational simulations are carried out in MATLAB and use the NIST REFPROP database for modeling the high pressure (on the order of 1000 MPa) CO2 state points. Preliminary results show that the maximum energy that can be recovered using the proposed high pressure cycle in on the order of 11,043 J, for each mole of CO2 flowing in the cycle. Thus the Coefficient of Performance is COP = 2.22, and the efficiency of the cycle is estimated as η = 35%. Future work will focus on the development of equipment such as the cryogenic turbo-expander that can operate at the ultra-high pressures studied.

Tribological Studies of Compressor Surfaces in the Presence of Carbon Dioxide Under Extreme Environmental Pressure Conditions

2005 ◽  
Author(s):  
Nicholaos G. Demas ◽  
Andreas A. Polycarpou
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
High Pressures ◽  
Environmental Pressures ◽  
Thermodynamic Studies ◽  
Environmental Pressure ◽  
Ultra High Pressure ◽  
Carbon Dioxide Co2 ◽  
Internal Pressures ◽  
Very High

The refrigeration industry has shown an inclination towards the use of carbon dioxide (CO2) as a refrigerant in some applications. While extensive thermodynamic studies exist, tribological studies with CO2 are limited and tribological testing has further been restricted to low environmental pressures up to 1.38 MPa (200 psi) due to limitations in equipment capabilities. In this work, experiments were performed using an Ultra High Pressure Tribometer (UHPT) that was custom designed and built for tribological testing of compressor contact interfaces at very high environmental pressures up to 13.8 MPa (2000 psi). These tests demonstrate the possibility of testing at very high pressures similar to the internal pressures of CO2 compressors.

scholarly journals High-pressure synthesis of materials with new bonding patterns and stoichiometries

2014 ◽  
Vol 70 (a1) ◽  
pp. C750-C750
Author(s):  
Alexander Goncharov
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Ambient Pressure ◽  
Detailed Knowledge ◽  
New Materials ◽  
Practical Applications ◽  
Theoretical Predictions ◽  
Physical And Chemical ◽  
Synthesis Of Materials ◽  
Bonding Patterns

The search for new materials for advanced technological and practical applications requires breakthroughs in our understanding of how we can control matter most efficiently. Pressure is arguably the most revealing physical variable to delineate various competing physical and chemical phenomena. There are multiple theoretical predictions for existence of novel materials state via changes in the equilibrium chemical bonding at high pressures, but many of these reports do not take into account a possible change in the most stable chemical composition. Also, the implications of this novel extreme chemistry for synthesis of new materials for practical applications remain challenging because high-pressure bonding patterns are often thermodynamically unstable at ambient pressure. Search for a recovery mechanisms or attempts of synthesis in nominally metastable conditions require detailed knowledge of the energy landscape; extensive collaborative efforts of experiment and theory are needed for its determination and for validating the theoretical predictions. I will present new results on synthesis of materials with new bonding patterns and unusual stoichiometries containing hydrogen, nitrogen, carbon, sodium, and halogens. This work has been performed in collaboration with M. Somayazulu, V. V. Struzhkin, V. Prakapenka, E. Stavrou, T. Muramatsu, A. R. Oganov, W. Zhang, Q. Zhu, S. E. Boulfelfel, A. O. Lyakhov, Z. Konopkova, H.-P. Liermann, D.-Y. Kim. I acknowledge the support of DARPA, NSF, EFRee (DOE), Army Research Office, Deep Carbon Observatory, and Carnegie Institution of Washington.

Bullying, School Violence, and Climate in Evolving Contexts

2018 ◽  
Author(s):  
Ron Avi Astor ◽  
Rami Benbenisthty
Keyword(s):  
School Violence ◽  
School Safety ◽  
Media Coverage ◽  
Large Scale ◽  
Ecological Model ◽  
Empirical Studies ◽  
Practical Applications ◽  
Teacher Student ◽  
Area Of Interest ◽  
New Research

Since 2005, the bullying, school violence, and school safety literatures have expanded dramatically in content, disciplines, and empirical studies. However, with this massive expansion of research, there is also a surprising lack of theoretical and empirical direction to guide efforts on how to advance our basic science and practical applications of this growing scientific area of interest. Parallel to this surge in interest, cultural norms, media coverage, and policies to address school safety and bullying have evolved at a remarkably quick pace over the past 13 years. For example, behaviors and populations that just a decade ago were not included in the school violence, bullying, and school safety discourse are now accepted areas of inquiry. These include, for instance, cyberbullying, sexting, social media shaming, teacher–student and student–teacher bullying, sexual harassment and assault, homicide, and suicide. Populations in schools not previously explored, such as lesbian, gay, bisexual, transgender, and queer students and educators and military- and veteran-connected students, become the foci of new research, policies, and programs. As a result, all US states and most industrialized countries now have a complex quilt of new school safety and bullying legislation and policies. Large-scale research and intervention funding programs are often linked to these policies. This book suggests an empirically driven unifying model that brings together these previously distinct literatures. This book presents an ecological model of school violence, bullying, and safety in evolving contexts that integrates all we have learned in the 13 years, and suggests ways to move forward.

Sign in / Sign up

Export Citation Format

Share Document