Towards traceable transient pressure metrology

Geological carbon storage is an effective method capable of reducing carbon dioxide (CO2) emissions at significant scales. Subsurface reservoirs with sealing caprocks can provide long-term containment for the injected fluid. Nevertheless, CO2 leakage is a major concern. The presence of abandoned wells penetrating the reservoir caprock may cause leakage flow-paths for CO2 to the overburden. Assessment of time-varying leaky wells is a need. In this paper, we propose a new semi-analytical approach based on pressure-transient analysis to model the behavior of CO2 leakage and corresponding pressure distribution within the storage site and the overburden. Current methods assume instantaneous leakage of CO2 occurring with injection, which is not realistic. In this work, we employ the superposition in time and space to solve the diffusivity equation in 2D radial flow to approximate the transient pressure in the reservoirs. Fluid and rock compressibilities are taken into consideration, which allow calculating the breakthrough time and the leakage rate of CO2 to the overburden accurately. We use numerical simulations to verify the proposed time-dependent semi-analytical solution. The results show good agreement in both pressure and leakage rates. Sensitivity analysis is then conducted to assess different CO2 leakage scenarios to the overburden. The developed semi-analytical solution provides a new simple and practical approach to assess the potential of CO2 leakage outside the storage site. This approach is an alternative to numerical methods when detailed simulations are not feasible. Furthermore, the proposed solution can also be used to verify numerical codes, which often exhibit numerical artifacts.

Download Full-text

Effect of air mass fraction on transient pressure and structural integrity assessment in a relatively long cast iron pipe

Engineering Failure Analysis ◽

10.1016/j.engfailanal.2021.105293 ◽

2021 ◽

Vol 122 ◽

pp. 105293

Author(s):

Lamjed Hadj Taieb ◽

Noura Bettaieb ◽

Sami Elaoud

Keyword(s):

Cast Iron ◽

Mass Fraction ◽

Structural Integrity ◽

Transient Pressure ◽

Air Mass ◽

Integrity Assessment

Download Full-text

Failure analysis of fiberglass‐vinyl ester composite cylinders subjected to fire and asymmetric transient pressure

Polymer Composites ◽

10.1002/pc.26251 ◽

2021 ◽

Author(s):

Ehsan Selahi ◽

Ali Reza Setoodeh ◽

Masoud Tahani

Keyword(s):

Failure Analysis ◽

Vinyl Ester ◽

Transient Pressure ◽

Composite Cylinders

Download Full-text

Prediction of Transient Pressure Fluctuations within a Low-Pressure Turbine Cascade Using a Lanczos-Filtered Harmonic Balance Method

International Journal of Turbomachinery Propulsion and Power ◽

10.3390/ijtpp6030025 ◽

2021 ◽

Vol 6 (3) ◽

pp. 25

Author(s):

Jan Philipp Heners ◽

Stephan Stotz ◽

Annette Krosse ◽

Detlef Korte ◽

Maximilian Beck ◽

...

Keyword(s):

Turbulence Model ◽

Harmonic Balance ◽

Separation Bubble ◽

Pressure Fluctuations ◽

Harmonic Balance Method ◽

Low Pressure ◽

Filter Method ◽

Turbine Cascade ◽

Transient Pressure ◽

Low Pressure Turbine

Unsteady pressure fluctuations measured by fast-response pressure transducers mounted in a low-pressure turbine cascade are compared to unsteady simulation results. Three differing simulation approaches are considered, one time-integration method and two harmonic balance methods either resolving or averaging the time-dependent components within the turbulence model. The observations are used to evaluate the capability of the harmonic balance solver to predict the transient pressure fluctuations acting on the investigated stator surface. Wakes of an upstream rotor are generated by moving cylindrical bars at a prescribed rotational speed that refers to a frequency of f∼500 Hz. The excitation at the rear part of the suction side is essentially driven by the presence of a separation bubble and is therefore highly dependent on the unsteady behavior of turbulence. In order to increase the stability of the investigated harmonic balance solver, a developed Lanczos-type filter method is applied if the turbulence model is considered in an unsteady fashion.

Download Full-text

Active site densities, oxygen activation and adsorbed reactive oxygen in alcohol activation on npAu catalysts

Faraday Discussions ◽

10.1039/c5fd00161g ◽

2016 ◽

Vol 188 ◽

pp. 57-67 ◽

Cited By ~ 14

Author(s):

Lu-Cun Wang ◽

C. M. Friend ◽

Rebecca Fushimi ◽

Robert J. Madix

Keyword(s):

Selective Oxidation ◽

Activation Barrier ◽

Initial Step ◽

Temporal Analysis ◽

Adsorbed Oxygen ◽

Transient Pressure ◽

Pulse Reaction ◽

Dissociation Probability ◽

Oxidation Of Methanol ◽

Oxygen Atoms

The activation of molecular O2 as well as the reactivity of adsorbed oxygen species is of central importance in aerobic selective oxidation chemistry on Au-based catalysts. Herein, we address the issue of O2 activation on unsupported nanoporous gold (npAu) catalysts by applying a transient pressure technique, a temporal analysis of products (TAP) reactor, to measure the saturation coverage of atomic oxygen, its collisional dissociation probability, the activation barrier for O2 dissociation, and the facility with which adsorbed O species activate methanol, the initial step in the catalytic cycle of esterification. The results from these experiments indicate that molecular O2 dissociation is associated with surface silver, that the density of reactive sites is quite low, that adsorbed oxygen atoms do not spill over from the sites of activation onto the surrounding surface, and that methanol reacts quite facilely with the adsorbed oxygen atoms. In addition, the O species from O2 dissociation exhibits reactivity for the selective oxidation of methanol but not for CO. The TAP experiments also revealed that the surface of the npAu catalyst is saturated with adsorbed O under steady state reaction conditions, at least for the pulse reaction.

Download Full-text