Measurements of Decompression Wave Speed in Simulated Anthropogenic Carbon Dioxide Mixtures Containing Hydrogen

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
K. K. Botros ◽  
J. Geerligs ◽  
B. Rothwell ◽  
T. Robinson
Keyword(s):  
Carbon Dioxide ◽  
Shock Tube ◽  
Phase Boundary ◽  
Ductile Fracture ◽  
Critical Point ◽  
Wave Speed ◽  
Plateau Pressure ◽  
Boundary Crossing ◽  
Decompression Wave ◽  
The Impact

In order to determine the material fracture resistance necessary to provide adequate control of ductile fracture propagation in a pipeline, a knowledge of the decompression wave speed following the quasi-instantaneous formation of an unstable, full-bore rupture is necessary. The thermodynamic and fluid dynamics background of such calculations is understood, but predictions based on specific equations of state (EOS) need to be validated against experimental measurements. A program of tests has been conducted using a specially constructed shock tube to determine the impact of impurities on the decompression wave speed in carbon dioxide (CO2), so that the results can be compared to two existing theoretical models. In this paper, data and analysis results are presented for three shock tube tests involving anthropogenic CO2 mixtures containing hydrogen as the primary impurity. The first mixture was intended to represent a typical scenario of precombustion carbon capture and storage (CCS) technology, where typically the concentration of CO2 is around 95–97% (mole). The second mixture represents a worst case scenario of this technology with high level of impurities (with CO2 concentration around 85%). The third test represents a typical chemical-looping combustion process. It was found that the extent of the plateau on the decompression wave speed curves in these tests depends on the location of the phase boundary crossing along the bubble-point curve. The closer the phase boundary crossing to the critical point, the shorter the plateau. This is primarily due to the change in magnitude of the drop in the speed of sound at phase boundary crossing. For the most part, the predictions of the plateau pressure by both of the EOS that were evaluated, GERG-2008 and Peng–Robinson (PR), are in good agreement with measurements by the shock tube. This by no means reflects overall good performance of either EOS, but was rather due to the fact that the isentropes intersected the phase envelope near the critical point, or that the concentration of H2 was relatively low, either in absolute terms or relative to other impurity constituents. Hence, its influence in causing inaccurate prediction of the plateau pressure is lessened. An example of pipeline material toughness required to arrest ductile fracture is presented which shows that predictions by GERG-2008 are more conservative and are therefore recommended.

Measurements of Decompression Wave Speed in Natural Gas Containing 2-8% (Mole) Hydrogen by a Specialized Shock Tube

2016 ◽  
Author(s):  
K. K. Botros ◽  
S. Igi ◽  
J. Kondo
Keyword(s):  
Natural Gas ◽  
Shock Tube ◽  
Hydrogen Concentration ◽  
Wave Speed ◽  
Accurate Determination ◽  
Initial Pressure ◽  
Propagation Speed ◽  
Wave Speeds ◽  
Decompression Wave ◽  
Curve Method

The Battelle two-curve method is widely used throughout the industry to determine the required material toughness to arrest ductile (or tearing) pipe fracture. The method relies on accurate determination of the propagation speed of the decompression wave into the pipeline once the pipe ruptures. GASDECOM is typically used for calculating this speed, and idealizes the decompression process as isentropic and one-dimensional. While GASDECOM was initially validated against quite a range of gas compositions and initial pressure and temperature, it was not developed for mixtures containing hydrogen. Two shock tube tests were conducted to experimentally determine the decompression wave speed in lean natural gas mixtures containing hydrogen. The first test had hydrogen concentration of 2.88% (mole) while the second had hydrogen concentration of 8.28% (mole). The experimentally determined decompression wave speeds from the two tests were found to be very close to each other despite the relatively vast difference in the hydrogen concentrations for the two tests. It was also shown that the predictions of the decompression wave speed using the GERG-2008 equation of state agreed very well with that obtained from the shock tube measurements. It was concluded that there is no effects of the hydrogen concentration (between 0–10% mole) on the decompression wave speed, particularly at the lower part (towards the choked pressure) of the decompression wave speed curve.

Measurements of Decompression Wave Speed in Pure Carbon Dioxide and Comparison With Predictions by Equation of State

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
K. K. Botros ◽  
J. Geerligs ◽  
B. Rothwell ◽  
T. Robinson
Keyword(s):  
Carbon Dioxide ◽  
Large Scale ◽  
Wave Speed ◽  
Equations Of State ◽  
Initial Conditions ◽  
Thermodynamic Characteristics ◽  
Point Of View ◽  
Decompression Wave ◽  
Rapid Transients

Carbon dioxide capture and storage (CCS) is one of the technologies that have been proposed to reduce emissions of carbon dioxide (CO2) to the atmosphere. CCS will require the transportation of the CO2 from the “capture” locations to the “storage” locations via large-scale pipeline projects. One of the key requirements for the design and operation of pipelines in all jurisdictions is fracture control. Supercritical CO2 is a particularly challenging fluid from this point of view, because its thermodynamic characteristics are such that a very high driving force for fracture can be sustained for a long time. Even though CO2 is not flammable, it is an asphyxiating gas that is denser than air, and can collect in low-lying areas. Additionally, it is well known that any pipeline rupture, regardless of the nature of the fluid it is transporting, has a damaging reputational, commercial, logistic, and end user impact. Therefore, it is as important to control fracture in a CO2 pipeline as in one transporting a flammable fluid. With materials specified appropriately for the prevention of brittle failure, the key element is the control of propagating ductile (or tearing) fracture. The determination of the required toughness for the arrest of ductile fracture requires knowledge of the decompression behavior of the contained fluid, which in turn requires accurate knowledge of its thermodynamic characteristics along the decompression isentrope. While thermodynamic models based on appropriate EOS (equations of state) are available that will, in principle, allow determination of the decompression wave speed, they, in general, have not been fully validated for very rapid transients following a rupture. This paper presents experimental results of the decompression wave speed obtained from shock tube tests conducted on pure CO2 from different initial conditions, and comparison with predictions by models based on GERG-2008, Peng-Robinson, and BWRS equations of state (EOS). These tests were conducted as a baseline before introducing various impurities.

Measurements of Decompression Wave Speed in Binary Mixtures of Carbon Dioxide and Impurities

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
K. K. Botros ◽  
J. Geerligs ◽  
B. Rothwell ◽  
T. Robinson
Keyword(s):  
Binary Mixtures ◽  
Wave Speed ◽  
Equations Of State ◽  
Propagation Speed ◽  
Plateau Pressure ◽  
Wave Speeds ◽  
Decompression Wave ◽  
Arrest Toughness ◽  
Good Agreement

Shock tube tests were conducted on a number of binary CO2 mixtures with N2, O2, CH4, H2, CO, and Ar impurities, from a range of initial pressures and temperatures. This paper provides examples of results from these tests. The resulting decompression wave speeds are compared with predictions made utilizing different equations of state (EOS). It was found that, for the most part (except for binaries with H2), the GERG-2008 EOS shows much better performance than the Peng–Robinson (PR) EOS. All binaries showed a very long plateau in the decompression wave speed curves. It was also shown that tangency of the fracture propagation speed curve would normally occur on the pressure plateau, and hence, the accuracy of the calculated arrest toughness for pipelines transporting these binary mixtures is highly dependent on the accuracy of the predicted plateau pressure. Again, for the most part, GERG-2008 predictions of the plateau are in good agreement with the measurements in binary mixtures with N2, O2, and CH4. An example of the determination of pipeline material toughness required to arrest ductile fracture is presented, which shows that prediction by GERG-2008 is generally more conservative and is therefore recommended. However, both GERG-2008 and PR EOS show much worse performance for the other three binaries: CO2 + H2, CO2 + CO, and CO2 + Ar, with CO2 + H2 being the worst. This is likely due to the lack of experimental data for these three binary mixtures that were used in the development of these EOS.

scholarly journals Nonlinear Heat Transfer From Particles in Supercritical Carbon Dioxide Near the Critical Point

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Michael James Martin ◽  
Elizabeth G. Rasmussen ◽  
Shashank Yellapantula
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Thermal Conductivity ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
Materials Synthesis ◽  
Energy Technologies ◽  
Property Changes ◽  
The Impact ◽  
Supercritical Carbon

Abstract Particle to fluid heat transfer in supercritical carbon dioxide (sCO2) is encountered in energy technologies and in materials synthesis. Near the critical point, the extreme pressure and temperature sensitivity of sCO2’s thermal conductivity will change the expected heat transfer in these systems. The current work combines the Kirchoff transformation for thermal conductivity with the conduction shape factor for a sphere, allowing prediction of heat transfer in these systems and quantification of the impact of these property changes. Results show that the heat transfer is non-linear for supercritical heat transfer, with the non-linearity particularly significant near the critical point. The results also show that approaches such as an average thermal conductivity based on film temperature are unlikely to accurately predict heat transfer in this region. The methods described in this paper can be applied to fluid–particle heat transfer at low Reynolds number in other fluids with large variations in thermal conductivity.

Semi-Empirical Correlation to Quantify the Effects of Pipe Diameter and Internal Surface Roughness on the Decompression Wave Speed in Natural Gas Mixtures

2012 ◽  
Author(s):  
K. K. Botros ◽  
Lorne Carlson ◽  
Brian Rothwell ◽  
Philip Venton
Keyword(s):  
Surface Roughness ◽  
Natural Gas ◽  
Pressure Gradient ◽  
Shock Tube ◽  
Wave Speed ◽  
Correction Term ◽  
Gas Mixture ◽  
Decompression Wave ◽  
Semi Empirical ◽  
The Ideal

GASDECOM is typically used in the design of gas pipelines for calculating decompression speed in connection with the Battelle two-curve method used throughout the pipeline industry for the control of propagating ductile fracture. GASDECOM idealizes the decompression process as isentropic and one-dimensional, taking no account of pipe wall frictional effects. Previous shock tube tests showed that decompression wave speeds in smaller diameter and rough pipes are consistently slower than those predicted by GASDECOM for the same conditions of mixture composition and initial pressure and temperature. Preliminary analysis based on perturbation theory and the fundamental momentum equation showed a correction term to be subtracted from the ‘ideal’ value of the decompression speed. One parameter in this correction term involves a dynamic spatial pressure gradient of the outflow at the rupture location. While this is difficult to obtain without a shock tube or actual rupture test, data from 14 shock tube tests, as well as from 14 full scale burst tests involving a variety of gas mixture compositions, were analyzed to quantify the variation of this pressure gradient with gas conditions and outflow Mach number. A semi-empirical relationship was found to correlate this pressure gradient parameter with two basic parameters representing the natural gas mixture, namely the molecular weight of the mixture and its higher heating value (HHV). For lean gas mixes, the semi-empirically obtained correlation was found to fit very well the experimentally determined decompression wave speed curve. For rich gas mixes, the correlation fits both branches of the curve; above and below the plateau pressure. This paper provides the basis for the derived semi-empirical correlation, and suggests a procedure (with examples) to correct the ‘ideal’ (frictionless) GASDECOM prediction to account for both the effects of pipe diameter and pipe internal wall surface roughness.

The Critical Point Drying Method Applied to Scanning Electron Microscopy of L-929 Cells

1970 ◽  
Vol 28 ◽  
pp. 278-279
Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Surface Tension ◽  
Critical Point ◽  
Freeze Drying ◽  
Attractive Alternative ◽  
Crystal Formation ◽  
Critical Point Drying ◽  
Time Required ◽  
Scanning Electron

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.

Climate-forced changes of bio-productivity of Belorussian terrestrial ecosystems

2019 ◽  
pp. 77-88
Author(s):  
S. A. Lysenko
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Vegetation Index ◽  
Precipitation Amount ◽  
Terrestrial Ecosystems ◽  
Vegetation Period ◽  
Climatic Trend ◽  
Vegetation Growth ◽  
Current Century ◽  
The Impact

The spatial and temporal particularities of Normalized Differential Vegetation Index (NDVI) changes over territory of Belarus in the current century and their relationship with climate change were investigated. The rise of NDVI is observed at approximately 84% of the Belarus area. The statistically significant growth of NDVI has exhibited at nearly 35% of the studied area (t-test at 95% confidence interval), which are mainly forests and undeveloped areas. Croplands vegetation index is largely descending. The main factor of croplands bio-productivity interannual variability is precipitation amount in vegetation period. This factor determines more than 60% of the croplands NDVI dispersion. The long-term changes of NDVI could be explained by combination of two factors: photosynthesis intensifying action of carbon dioxide and vegetation growth suppressing action of air warming with almost unchanged precipitation amount. If the observed climatic trend continues the croplands bio-productivity in many Belarus regions could be decreased at more than 20% in comparison with 2000 year. The impact of climate change on the bio-productivity of undeveloped lands is only slightly noticed on the background of its growth in conditions of rising level of carbon dioxide in the atmosphere.

Sign in / Sign up

Export Citation Format

Share Document