The Experts below are selected from a list of 22821 Experts worldwide ranked by ideXlab platform
Ayyoub M. Momen - One of the best experts on this subject based on the ideXlab platform.
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Thermal analysis of near-isothermal Compressed Gas energy storage system
Applied Energy, 2016Co-Authors: Adewale Odukomaiya, Ahmad Abu-heiba, Roderick K Jackson, Kyle R. Gluesenkamp, Claus Daniel, Omar Abdelaziz, Samuel Graham, Ayyoub M. MomenAbstract:Due to the increasing generation capacity of intermittent renewable electricity sources and an electrical grid ill-equipped to handle the mismatch between electricity generation and use, the need for advanced energy storage technologies will continue to grow. Currently, pumped-storage hydroelectricity and Compressed air energy storage are used for grid-scale energy storage, and batteries are used at smaller scales. However, prospects for expansion of these technologies suffer from geographic limitations (pumped-storage hydroelectricity and Compressed air energy storage), low roundtrip efficiency (Compressed air energy storage), and high cost (batteries). Furthermore, pumped-storage hydroelectricity and Compressed air energy storage are challenging to scale-down, while batteries are challenging to scale-up. In 2015, a novel Compressed Gas energy storage prototype system was developed at Oak Ridge National Laboratory. In this paper, a near-isothermal modification to the system is proposed. In common with Compressed air energy storage, the novel storage technology described in this paper is based on air compression/expansion. However, several novel features lead to near-isothermal processes, higher efficiency, greater system scalability, and the ability to site a system anywhere. The enabling features are utilization of hydraulic machines for expansion/compression, above-ground pressure vessels as the storage medium, spray cooling/heating, and waste-heat utilization. The base configuration of the novel storage system was introduced in a previous paper. This paper describes the results obtained from a transient, analytical, physics-based thermodynamic system model used for the system design and evaluation of three design configurations (including base configuration). The system model captures real Gas effects and all loss mechanisms. The model demonstrates an energy storage roundtrip efficiency of 82% and energy density of 3.59 MJ/m3. Experimental evaluation of system performance and detailed cost-analysis will be presented in future publications.
Abdul Hai Alami - One of the best experts on this subject based on the ideXlab platform.
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experimental study of carbon dioxide as working fluid in a closed loop Compressed Gas energy storage system
Renewable Energy, 2019Co-Authors: Abdul Hai Alami, Abdullah Abu Hawili, Rita Hassan, Mohammed Alhemyari, Kamilia AokalAbstract:This paper investigates the utilization of carbon dioxide Gas available in mass pressurized storage caverns as a working fluid for a modular low pressure Compressed Gas energy storage (CGES) system. The system is made up of three 7 L cylinders that discharge into an air turbine to convert the system potential energy into kinetic and eventually into electricity through an onboard generator. The operating pressures are kept low (around 3 bar) in order to maintain the adiabatic operational assumption and not necessitate the usage of heat exchangers. The Gas is then rerouted back into the storage cavern after expansion. The reported energy conversion efficiency is 46.2% for the three active cylinders operating in tandem and 76.4% for them operating in unison. The main advantage of the proposed system is its flexibility to function under high power density for the latter or high energy density requirements for the former arrangement, respectively. This level of discharge control allows the system to serve in ranges that previously required independent storage systems addressing narrow power/energy density needs. This charge/discharge cycle takes advantage of the availability of the stored and pressurized carbon dioxide, which is denser than air and hence produced higher power output and required 65% less space than its air-operated counterpart.
Namas Chandra - One of the best experts on this subject based on the ideXlab platform.
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dynamic loads on human and animal surrogates at different test locations in Compressed Gas driven shock tubes
Shock Waves, 2018Co-Authors: Eren Alay, Maciej Skotak, Anthony Misistia, Namas ChandraAbstract:Dynamic loads on specimens in live-fire conditions as well as at different locations within and outside Compressed-Gas-driven shock tubes are determined by both static and total blast overpressure–time pressure pulses. The biomechanical loading on the specimen is determined by surface pressures that combine the effects of static, dynamic, and reflected pressures and specimen geometry. Surface pressure is both space and time dependent; it varies as a function of size, shape, and external contour of the specimens. In this work, we used two sets of specimens: (1) anthropometric dummy head and (2) a surrogate rodent headform instrumented with pressure sensors and subjected them to blast waves in the interior and at the exit of the shock tube. We demonstrate in this work that while inside the shock tube the biomechanical loading as determined by various pressure measures closely aligns with live-fire data and shock wave theory, significant deviations are found when tests are performed outside.
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a parametric approach to shape field relevant blast wave profiles in Compressed Gas driven shock tube
Frontiers in Neurology, 2014Co-Authors: Aravind Sundaramurthy, Namas ChandraAbstract:Detonation of a high explosive produces shock-blast wave, shrapnel, and Gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects even at farther distances, which is termed as primary blast injury, which is the theme of this work. The shock-blast profile is characterized with blast overpressure, positive time duration, and impulse as shock-blast wave parameters (SWPs). These parameters in turn are a function of field factors, such as the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (Chandra et al., 2011;Sundaramurthy et al., 2012;Skotak et al., 2013), the profile not only determines the survival of the animal but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, exact replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. 40 experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68 to 1209.68 mm), measurement location, and type of driver Gas (nitrogen, helium). The relationships between SAPs and the resulting shock-blast profiles are characterized. Finally, shock-blast profiles of a TNT explosion from ConWep software is compared with the profiles obtained from the tube.
F Wieder - One of the best experts on this subject based on the ideXlab platform.
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three dimensional study of Compressed Gas diffusion layers using synchrotron x ray imaging
Journal of Power Sources, 2014Co-Authors: Christian Totzke, Gerd Gaiselmann, Markus Osenberg, Jens Bohner, Tobias Arlt, Henning Markotter, Andre Hilger, F WiederAbstract:Abstract We present a synchrotron X-ray tomographic study on the morphology of carbon fiber-based Gas diffusion layer (GDL) material under compression. A dedicated compression device is used to provide well-defined compression conditions. A flat compression punch is employed to study the fiber geometry at different degrees of compression. Transport relevant geometrical parameters such as porosity, pore size and tortuosity distributions are calculated. The geometric properties notably change upon compression which has direct impact on transport conditions for Gas and fluid flow. The availability of broad 3D paths, which are most important for the transport of liquid water from the catalyst layer through the GDL, is markedly reduced after compression. In a second experiment, we study the influence of the channel-land-pattern of the flow-field on shape and microstructure of the GDL. A flow-field compression punch is employed to reproduce the inhomogeneous compression conditions found during fuel cell assembly. While homogenously Compressed underneath the land the GDL is much less and inhomogeneously Compressed under the channel. The GDL material extends far into the channel volume where it can considerably influence Gas and fluid flow. Loose fiber endings penetrate deeply into the channel and form obstacles for the discharge of liquid water droplets.
John S Rubin - One of the best experts on this subject based on the ideXlab platform.
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otorhinolaryngology and diving part 1 otorhinolaryngological hazards related to Compressed Gas scuba diving a review
Archives of Otolaryngology-head & Neck Surgery, 2018Co-Authors: Matt Lechner, Liam Sutton, Jonathan Fishman, David M Kaylie, Richard E Moon, Liam Masterson, Christoph Klingmann, Martin A Birchall, Valerie J Lund, John S RubinAbstract:Importance Scuba diving is becoming increasingly popular. However, scuba diving is associated with specific risks; 80% of adults and 85% of juvenile divers (aged 6-17 years) have been reputed to have an ear, nose, or throat complaint related to diving at some point during their diving career. Divers frequently seek advice from primary care physicians, diving physicians, and otorhinolaryngologists, not only in the acute setting, but also related to the long-term effects of diving. Observations The principles underpinning diving-related injuries that may present to the otorhinolaryngologist rely on Gas volume and Gas saturation laws, and the prevention of these injuries requires both that the diver is skilled and that their anatomy allows for pressure equalization between the various anatomical compartments. The overlapping symptoms of middle ear barotrauma, inner ear barotrauma, and inner ear decompression sickness can cause a diagnostic conundrum, and a thorough history of both the diver’s symptoms and the dive itself are required to elucidate the diagnosis. Correct diagnosis and appropriate treatment result in a more timely return to safe diving. Conclusions and Relevance The aim of this review is to provide a comprehensive overview of otorhinolaryngological complications during diving. With the increasing popularity of diving and the frequency of ear, nose, or throat–related injuries, it could be expected that these injuries will become more common and this review provides a resource for otorhinolaryngologists to diagnose and treat these conditions.
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otorhinolaryngology and diving part 2 otorhinolaryngological fitness for Compressed Gas scuba diving a review
Archives of Otolaryngology-head & Neck Surgery, 2018Co-Authors: Matt Lechner, Liam Sutton, Jonathan Fishman, David M Kaylie, Richard E Moon, Liam Masterson, Christoph Klingmann, Martin A Birchall, Valerie J Lund, John S RubinAbstract:Importance Self-contained underwater breathing apparatus (scuba) diving has become increasingly popular with millions of people diving each year. Otorhinolaryngologists are often consulted either by patients or diving physicians regarding fitness to dive, and at present, the guidelines do not provide comprehensive information regarding the evaluation of this patient cohort. The aim of this review is to provide a comprehensive overview of existing otorhinolaryngological guidelines for fitness to dive recreationally. Observations There is a paucity of guidelines for assessing otorhinolaryngological fitness to dive in the recreational diver. Comprehensive guidelines exist from US, European, and UK regulatory bodies regarding fitness for commercial diving; however, not all of these can be directly extrapolated to the recreational diver. There are also a variety of conditions that are not covered either by the existing fitness for recreational diving guidelines or the commercial regulatory bodies. Conclusions and Relevance With the paucity of recreational fitness to dive guidelines we must draw on information from the commercial diving regulatory bodies. We have provided our own recommendations on the conditions that are not covered by either of the above, to provide otorhinolaryngologists with the information they require to assess fitness for recreational diving.