scholarly journals Numerical modelling of hydrogen release and dispersion

2021 ◽  
Vol 342 ◽  
pp. 01004
Author(s):  
Vlad Mihai Pasculescu ◽  
Marius Cornel Suvar ◽  
Ligia Ioana Tuhut ◽  
Laurentiu Munteanu
Keyword(s):  
Land Use Planning ◽  
High Efficiency ◽  
Atmospheric Dispersion ◽  
Software Tool ◽  
Pressure Vessels ◽  
Hydrogen Release ◽  
Protection Measures ◽  
Accidental Release ◽  
Pressure Tank ◽  
Simulation Results

Hydrogen is the most abundant element on earth, being a low polluting and high efficiency fuel that can be used for various applications, such as power generation, heating or transportation. As a reaction to climate change, authorities are working for determining the most promising applications for hydrogen, one of the best examples of crossborder initiative being the IPCEI (Important Project of Common European Interest) on Hydrogen, under development at EU level. Given the large interest for future uses of hydrogen, special safety measures have to be implemented for avoiding potential accidents. If hydrogen is stored and used under pressure, accidental leaks from pressure vessels may result in fires or explosions. Worldwide, researchers are investigating possible accidents generated by hydrogen leaks. Special attention is granted to the atmospheric dispersion after the release, so that to avoid fires or explosions. The use of consequence modelling software within safety and risk studies has shown its’ utility worldwide. In this paper, there are modelled the consequences of the accidental release and atmospheric dispersion of hydrogen from a pressure tank, using state-of-the-art QRA software. The simulation methodology used in this paper uses the “leak” model for carrying out discharge calculations. This model calculates the release rate and state of the gas after its expansion to atmospheric pressure. Accidental release of hydrogen is modelled by taking into account the process and meteorological conditions and the properties of the release point. Simulation results can be used further for land use planning, or may be used for establishing proper protection measures for surrounding facilities. In this work, we analysed two possible accident scenarios which may occur at an imaginary hydrogen refuelling station, accidents caused by the leaks of the pressure vessel, with diameters of 10 and 20 mm, for a pressure tank filled with hydrogen at 35 MPa / 70 MPa. Process Hazard Analysis Software Tool 8.4 has been used for assessing the effects of the scenarios and for evaluating the hazardous extent around the analysed installation. Accident simulation results have shown that the leak size has an important effect on the flammable/explosive ranges. Also, the jet fire’s influence distance is strongly influenced by the pressure and actual size of the accidental release.

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

scholarly journals Monte Carlo Modeling and Design of Photon Energy Attenuation Layers for >10× Quantum Yield Enhancement in Si-Based Hard X-ray Detectors

Instruments ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 17
Author(s):  
Eldred Lee ◽  
Kaitlin M. Anagnost ◽  
Zhehui Wang ◽  
Michael R. James ◽  
Eric R. Fossum ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Quantum Yield ◽  
Photon Energy ◽  
High Efficiency ◽  
High Energy ◽  
Yield Enhancement ◽  
X Ray ◽  
Simulation Results ◽  
Conversion Efficiencies

High-energy (>20 keV) X-ray photon detection at high quantum yield, high spatial resolution, and short response time has long been an important area of study in physics. Scintillation is a prevalent method but limited in various ways. Directly detecting high-energy X-ray photons has been a challenge to this day, mainly due to low photon-to-photoelectron conversion efficiencies. Commercially available state-of-the-art Si direct detection products such as the Si charge-coupled device (CCD) are inefficient for >10 keV photons. Here, we present Monte Carlo simulation results and analyses to introduce a highly effective yet simple high-energy X-ray detection concept with significantly enhanced photon-to-electron conversion efficiencies composed of two layers: a top high-Z photon energy attenuation layer (PAL) and a bottom Si detector. We use the principle of photon energy down conversion, where high-energy X-ray photon energies are attenuated down to ≤10 keV via inelastic scattering suitable for efficient photoelectric absorption by Si. Our Monte Carlo simulation results demonstrate that a 10–30× increase in quantum yield can be achieved using PbTe PAL on Si, potentially advancing high-resolution, high-efficiency X-ray detection using PAL-enhanced Si CMOS image sensors.

Thermal Performance Evaluation of Friction Stir Welded Flat Plate Heat Sink Using CFD Analysis

2015 ◽  
Vol 787 ◽  
pp. 505-509
Author(s):  
A.K. Lakshminarayanan ◽  
M. Suresh
Keyword(s):  
Flat Plate ◽  
Heat Sink ◽  
High Efficiency ◽  
Base Plate ◽  
Software Tool ◽  
Cover Plate ◽  
Air Cooling ◽  
Cooling Systems ◽  
Plate Heat ◽  
Friction Stir

In an era of compact cooling requirements, where air cooling systems seem to be ineffective and consistently, being replaced by liquid cooled systems, with greater watt density heat energy dissipation. Such cooling systems must work with good quality enabling high efficiency. Hence, an attempt is made to fabricate an aluminum alloy based flat plate heat sink with cover and base plate using friction stir welding. The base plate is machined to obtain channels for fluid flow and the cover plate is fitted in the base plate and welded. Two such configurations of these heat sinks were fabricated with varying channel lengths and number of channels. The flow characteristics of the model for these configurations were analyzed numerically using computational fluid dynamics (CFD) software tool, ANSYS fluent 14.

Research on Throttle Optimal Control of Flipper Jack for Hydraulic Support

2012 ◽  
Vol 503-504 ◽  
pp. 824-827
Author(s):  
Chun Qiang Jia ◽  
Wei Li ◽  
Ling Yu
Keyword(s):  
Optimal Control ◽  
Simulation Model ◽  
High Efficiency ◽  
Hydraulic Support ◽  
Simulation Results ◽  
Amesim Simulation

To solve the problem of support speed of hydraulic support flipper, the match relations between the flipper throttle control and shearer cutting coal speed are analyzed, the AMESim simulation model of the throttle optimal control for hydraulic support flipper jack is established, the simulation results show that flipper can be supported timely by speed optimal control of flipper jack which improve the reliability of the system and provide certain theory basis to meet the miner safety and high efficiency production.

scholarly journals Bandwidth calculation for VoIP networks based on PSTN statistical model

2010 ◽  
Vol 23 (1) ◽  
pp. 73-88 ◽  
Author(s):  
Zvezdan Stojanovic ◽  
Djordje Babic
Keyword(s):  
Statistical Model ◽  
Software Tool ◽  
Traffic Analysis ◽  
Proper Number ◽  
Simulation Results

This paper shows an analysis how to calculate proper bandwidth for VoIP calls after proper dimensioning of PSTN network. For this purpose, we use Erlang B and extended Erlang B formulae. Further, we have developed a software tool, named Bandwidth Calculator to calculate proper number of the circuits on the PSTN side and after that IP bandwidth. Traffic analysis is conducted for VoIP networks considering impact of many factors on the bandwidth such as: voice codecs, samples, VAD, RTP compression. The results obtained by bandwidth calculator are compared to simulation results and data obtained by measurements. .

scholarly journals Technology of Quick-Frozen Flour Fish Culinary Products

2022 ◽  
Author(s):  
Valentina Pavlova ◽  
Irina Saenkova ◽  
Yulia Shokina ◽  
Grigoriy Shokin
Keyword(s):  
Mass Fraction ◽  
High Efficiency ◽  
A Priori ◽  
Cholesterol Content ◽  
Organoleptic Evaluation ◽  
Amine Nitrogen ◽  
Long Term Storage ◽  
Functional Product ◽  
Simulation Results ◽  
Priori Information

In this article, the results of the development of the functional fish culinary product “Thorny Skate and Cod Pie” are presented. A traditional recipe was used for making the yeast dough for the pie. The pie filling recipe was designed using Fuzzy Logic in the Matlab software package.Optimized parametersfor the selected sensory evaluation of the pie were calculated. On the basis of a priori information, key components of the filling (including the fraction of the fish components and skate meat) were chosen as the factors of interest. According to the simulation results, the optimal values werea 50/50 percentage for the first and the second factor respectively, and this providedthe maximum organoleptic assessment (five points on a five-point scale). The simulation results were compared with the results of the organoleptic evaluation of the pie made according to the optimized recipe, and their sufficient convergence was shown. The indicators of mass fraction of amine nitrogen and nitrogen of volatile bases was studied, as well as the microbiological safety indicators of flour fish culinary products, in accordance with the requirements of the Technical Regulations of the Eurasian Economic Union 040/2016 ”On the safety of fish products”. The results showed a high efficiency of the shock freezing of the semi-finished product, brought to semi-readiness, for long-term storage (120 days at a temperature no higher than minus 18 ∘C), without reducing the quality or safety of the pie. The product had a cholesterol content from 220 to 260 mg%, which allowed it to be classified as functional. The nutritional values of the product (mass fraction of protein, fat, carbohydrates, and amino acid composition) are presented. Keywords: thornyskate, functional product, pie with thornyskate and cod, shock freezing

Numerical Simulation of Broadband Combustion Noise With the RPM-CN Approach

2009 ◽  
Author(s):  
B. Mu¨hlbauer ◽  
R. Ewert ◽  
O. Kornow ◽  
B. Noll ◽  
M. Aigner
Keyword(s):  
High Efficiency ◽  
Numerical Approach ◽  
Combustion Noise ◽  
Acoustic Measurements ◽  
Noise Sources ◽  
Computational Costs ◽  
Acoustic Perturbation ◽  
Simulation Results ◽  
The Time Domain ◽  
Good Agreement

A new numerical approach called RPM-CN approach is applied to predict broadband combustion noise. This highly efficient hybrid CFD/CAA approach can rely on a reactive RANS simulation. The RPM method is used to reconstruct stochastic broadband combustion noise sources in the time domain based on statistical turbulence quantities. Subsequently, the propagation of the combustion noise is computed by solving the acoustic perturbation equations (APE-4). The accuracy of the RPM-CN approach will be demonstrated by a good agreement of the simulation results with acoustic measurements of the DLR-A flame. The high efficiency and therefore low computational costs enable the usage of this numerical approach in the design process.

Fuzzy Control of Z-Source PV Grid-Connected Using Constant Frequency Hysteresis Comparison

2014 ◽  
Vol 852 ◽  
pp. 412-416 ◽  
Author(s):  
Yan Chen ◽  
Yong Zheng
Keyword(s):  
Fuzzy Control ◽  
High Efficiency ◽  
Filter Design ◽  
Control Performance ◽  
Tracking Accuracy ◽  
Constant Frequency ◽  
Simulation Results ◽  
Hysteresis Control ◽  
Pv Grid ◽  
Fast Dynamic

In order to achieve high efficiency of photovoltaic grid-connected system, the constant frequency hysteresis control is introduced into the Z-source grid-connected control, and realized by the fuzzy control technology. Because of the particularity of Z-source shoot-through working state, analyses shoot-through boosting characteristic of Z-source inverter and voltage control performance of DC-link, get the control signal of shoot-through vector. Add the shoot-through vector into hysteresis grid-connected control by using the logical analysis. This method has the advantages of fast dynamic response, high tracking accuracy and stability, and to overcome the traditional hysteresis control filter design is difficult. The simulation results prove the correctness of the theoretical analysis.

The Simulation of Temperature Field of 12Cr2Mo1R Ultra Thick Plate for Pressure Vessels during Heat Treatment by 3D-FEM

2014 ◽  
Vol 556-562 ◽  
pp. 472-475
Author(s):  
Yi Zhang ◽  
Guang Xu ◽  
Yue Yu ◽  
Hai Lin Yang ◽  
Ming Xing Zhou
Keyword(s):  
Heat Treatment ◽  
Temperature Field ◽  
Thick Plate ◽  
Pressure Vessels ◽  
Thickness Direction ◽  
Cooling Process ◽  
3D Fem ◽  
Treatment Technology ◽  
Quenching Temperature ◽  
Simulation Results

With ABAQUS software, a finite element model is built to simulate the temperature field of 150mm ultra thick plate for 12Cr2Mo1R pressure vessels during heat treatment. The simulation results show that the plate’s temperature between the surface and the core is difference during cooling process. Temperature difference is gradually increased with cooling process, then the temperature distribution of plate in the thickness direction becomes uniform. When quenching temperature is 910 °C and cooling medium is water, the microstructure at plate’s quarter in the thickness direction is bainite. Simulation results provide theoretical reference for determining heat treatment technology in industrial production of ultra thick plate.

scholarly journals High-Efficiency Simulation Framework to Analyze the Impact of Exhaust Air from COVID-19 Temporary Hospitals and its Typical Applications

2020 ◽  
Vol 10 (11) ◽  
pp. 3949 ◽  
Author(s):  
Donglian Gu ◽  
Zhe Zheng ◽  
Pengju Zhao ◽  
Linlin Xie ◽  
Zhen Xu ◽  
...  
Keyword(s):  
High Efficiency ◽  
Adverse Impact ◽  
Simulation Framework ◽  
Levels Of Detail ◽  
Surrounding Environment ◽  
Building Information ◽  
Simulation Results ◽  
Medical Infrastructure ◽  
The Impact ◽  
Different Levels

The outbreak of COVID-19 resulted in severe pressure on the existing medical infrastructure in China. Several Chinese cities began to construct temporary hospitals for the centralized treatment of COVID-19 patients. The harmful exhaust air from the outlets of these hospitals may have a significant adverse impact on the fresh-air intakes and surrounding environment. Owing to the need to rapidly construct these hospitals within 6–10 days, just a few hours are allowed for the analysis of the impact of this exhaust air on the environment. To overcome this difficulty, a high-efficiency simulation framework is proposed in this study. Based on the open-source computational fluid dynamics software, FDS, the proposed framework is adaptive and incorporates building information with different levels of detail during various design phases of the hospital, and has been applied in the design of the Wuhan Huoshenshan Hospital, the first typical COVID-19 temporary hospital in China. According to the simulation results, neither the fresh-air intakes nor the surrounding buildings would be polluted by the harmful air discharged from the air outlets of the Huoshenshan hospital. The proposed simulation framework can provide a reference for the design and overall planning of similar hospitals in China and other affected countries.

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