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Gases, Volume 1, Issue 1 (March 2021) – 5 articles

Cover Story (view full-size image): Ozone is a powerful oxidant having bactericidal, virucidal, and fungicidal actions, but also adverse effects on human health and safety. This paper suggests contact times and ozone concentrations needed for 90% inactivation of different viruses and explores the safety measures developed under the stimulus of the COVID-19 pandemic outbreak. Ozone generated in situ from ambient air can be used for disinfection of workplaces and public places, but afterwards, its concentration must be reduced to the Occupational Exposure Limit Values set in different European and extra European countries. The paper also examines the disinfection of disposable personal protective equipment for reuse. The optimal use of ozone is without human presence, at a concentration effective for the destruction of viruses, but not high enough to deteriorate materials. View this paper
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15 pages, 18109 KiB  
Article
A Visual Investigation of CO2 Convective Mixing in Water and Oil at the Pore Scale Using a Micromodel Apparatus at Reservoir Conditions
by Widuramina Amarasinghe, Seyed Farzaneh, Ingebret Fjelde, Mehran Sohrabi and Ying Guo
Gases 2021, 1(1), 53-67; https://0-doi-org.brum.beds.ac.uk/10.3390/gases1010005 - 28 Jan 2021
Cited by 3 | Viewed by 3963
Abstract
CO2 convective mixing in water has been visualized in Hele-Shaw and PVT cell experiments but not at the pore scale. Furthermore, CO2 convective mixing in a three-phase system (i.e., CO2 in the presence of both water and oil) has not [...] Read more.
CO2 convective mixing in water has been visualized in Hele-Shaw and PVT cell experiments but not at the pore scale. Furthermore, CO2 convective mixing in a three-phase system (i.e., CO2 in the presence of both water and oil) has not been visually investigated. A vertically placed micromodel setup was used to visualize CO2 convective mixing at 100 bar and 50 °C, representative of reservoir conditions. To the best of our knowledge, for the first time, we have visually investigated CO2 convective mixing in water at the pore scale and also CO2 convective mixing in a multiphase system (water and oil). CO2 mixing in water governed by both diffusion and convection mechanisms was observed. The vertical CO2 transport velocity was calculated to be 0.3 mm/min in both a 100% water saturation system and a residual oil-saturated system. First, CO2 always found the easiest path through the connected pores, and then CO2 was transported into less connected pores and dead-end pores. CO2 transport into dead-end pores was slower than through the preferential path. CO2 transport into water-filled ganglia with trapped oil was observed and was slower than in water. Full article
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2 pages, 314 KiB  
Editorial
Gases—An Open Access Journal
by Edward J. Anthony
Gases 2021, 1(1), 51-52; https://0-doi-org.brum.beds.ac.uk/10.3390/gases1010004 - 25 Jan 2021
Viewed by 2858
Abstract
Gases (ISSN 2673-5628) is an international and interdisciplinary peer-reviewed open access journal on gas science and engineering published quarterly online by MDPI [...] Full article
18 pages, 7705 KiB  
Article
Effects of Pressurizing Cryogenic Treatments on Physical and Mechanical Properties of Shale Core Samples—An Experimental Study
by Rayan Khalil, Hossein Emadi and Faisal Altawati
Gases 2021, 1(1), 33-50; https://0-doi-org.brum.beds.ac.uk/10.3390/gases1010003 - 20 Jan 2021
Cited by 2 | Viewed by 3362
Abstract
The technique of cryogenic treatments requires injecting extremely cold fluids such as liquid nitrogen (LN2) into formations to create fractures in addition to connecting pre-existing fracture networks. This study investigated the effects of implementing and pressurizing cryogenic treatment on the physical [...] Read more.
The technique of cryogenic treatments requires injecting extremely cold fluids such as liquid nitrogen (LN2) into formations to create fractures in addition to connecting pre-existing fracture networks. This study investigated the effects of implementing and pressurizing cryogenic treatment on the physical (porosity and permeability) and mechanical properties (Young’s modulus, Poisson’s ratio, and bulk compressibility) of the Marcellus shale samples. Ten Marcellus core samples were inserted in a core holder and heated to 66 °C using an oven. Then, LN2 (−177 °C) was injected into the samples at approximately 0.14 MPa. Nitrogen was used to pressurize nine samples at injection pressures of 1.38, 2.76, and 4.14 MPa while the tenth core sample was not pressurized. Using a cryogenic pressure transducer and a T-type thermocouple, the pressure and temperature of the core holder were monitored and recorded during the test. The core samples were scanned using a computed tomography (CT) scanner, and their porosities, permeability, and ultrasonic velocities were measured both before and after conducting the cryogenic treatments. The analyses of CT scan results illustrated that conducting cryogenic treatments created new cracks inside all the samples. These cracks increased the pore volume, and as a result, the porosity, permeability, and bulk compressibility of the core samples increased. The creations of the new cracks also resulted in reductions in the compressional and shear velocities of the samples, and as a result, decreasing the Young’s modulus and Poisson’s ratio. Moreover, the results revealed that pressurizing the injected LN2 increased the alterations of aforementioned properties. Full article
(This article belongs to the Section Natural Gas)
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14 pages, 444 KiB  
Technical Note
Safe and Effective Use of Ozone as Air and Surface Disinfectant in the Conjuncture of Covid-19
by Elena Grignani, Antonella Mansi, Renato Cabella, Paola Castellano, Angelo Tirabasso, Renata Sisto, Mariangela Spagnoli, Giovanni Fabrizi, Francesco Frigerio and Giovanna Tranfo
Gases 2021, 1(1), 19-32; https://0-doi-org.brum.beds.ac.uk/10.3390/gases1010002 - 24 Dec 2020
Cited by 44 | Viewed by 13983
Abstract
The present paper extrapolates quantitative data for ozone virucidal activity on the basis of the available scientific literature data for a safe and effective use of ozone in the appropriate cases and to explore the safety measures developed under the stimulus of the [...] Read more.
The present paper extrapolates quantitative data for ozone virucidal activity on the basis of the available scientific literature data for a safe and effective use of ozone in the appropriate cases and to explore the safety measures developed under the stimulus of the current emergency situation. Ozone is a powerful oxidant reacting with organic molecules, and therefore has bactericidal, virucidal, and fungicidal actions. At the same time, it is a toxic substance, having adverse effects on health and safety. Its use is being proposed for the disinfection of workplaces’ and public places’ atmosphere, and for disposable masks and personal protective equipment disinfection for reuse, with particular reference to the COVID-19 pandemic outbreak. Ozone can be generated in situ by means of small, compact ozone generators, using dried ambient air as a precursor. It should be injected into the room that is to be disinfected until the desired ozone concentration is reached; after the time needed for the disinfection, its concentrations must be reduced to the levels required for the workers’ safety. The optimal use of ozone is for air and surface disinfection without human presence, using a concentration that is effective for the destruction of viruses, but not high enough to deteriorate materials. Full article
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18 pages, 921 KiB  
Article
A Techno-Economic Perspective on Natural Gas and Its Value Chain
by Ruud Egging-Bratseth
Gases 2021, 1(1), 1-18; https://0-doi-org.brum.beds.ac.uk/10.3390/gases1010001 - 24 Nov 2020
Cited by 3 | Viewed by 3633
Abstract
We describe the elements and actors in the global natural gas value chains with an emphasis on characteristics relevant for large-scale energy system and market modeling. We give backgrounds on natural gas as a hydrocarbon to provide a rationale and understanding for what [...] Read more.
We describe the elements and actors in the global natural gas value chains with an emphasis on characteristics relevant for large-scale energy system and market modeling. We give backgrounds on natural gas as a hydrocarbon to provide a rationale and understanding for what functional representations in mathematical programming models aim to represent. Simply taking the most advanced and detailed functional forms for all value chain characteristics and activities will typically result in numerical intractability. One should carefully determine what is needed to address a research question or analyze a business case. Recent advances in mathematical programming do allow solving large models with adequate detail for many types of analysis. We discuss which functional forms and modeling approaches can be appropriate for representing various characteristics in different types of analysis and provide a succinct and general mathematical programming formulation reflecting the optimization problems for different types of actors in the value chain. We provide an implementation for a stylized network using GAMS. Full article
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