1,721,287 research outputs found
Kinetic modeling of the interactions between NO and hydrocarbons in the oxidation of hydrocarbons at low temperatures
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A wide range modeling study of NOx formation and nitrogen chemistry in hydrogen combustion
No full textThe Role of Radiative Heat Loss and Collisional Energy Transfer in the Flammability Limits of NH3 and NH3–H2 Mixtures
No full textUnderstanding the fundamental factors that define the flammable range of ammonia is essential for developing predictive tools to identify safe storage conditions, thereby facilitating its widespread use as an energy carrier. In this work, a numerical framework is established to predict and analyze the flammable range of ammonia and ammonia-hydrogen mixtures. To achieve this, a freely-propagating-flame method, adapted to account for radiation heat loss from nitrogen-containing species, is combined with an established ammonia oxidation mechanism, and the roles of initial temperature, pressure, and dilutant concentration are thoroughly investigated. It is found that, especially at the rich extinction limit, ammonia-related radiation plays a dominant role in causing an earlier extinction, especially at high initial temperatures. Also, the upper flammability limit is found to be particularly sensitive to third-body reactions. Incorporating ammonia collision efficiency into kinetic models is recommended as a key next step in enhancing the predictive accuracy of numerical tools
The ignition, combustion and flame structure of carbon monoxide/hydrogen mixtures. Note 1: Detailed kinetic modeling of syngas combustion also in presence of nitrogen compounds
No full textTRAM-R2: A Quantitative Model for Railway Tunnel Risk Analysis
Full text linkThe paper introduces TRAM-R2 (Tunnel Risk Analysis Model – Road&Railway), a novel quantitative risk analysis model for rail and road tunnels, compliant with European and Italian safety regulations. TRAM-R2 generates F-N curves, relating the frequency of accidental scenarios to potential fatalities, aligning with safety directives. It considers four initial events: collision, derailment, fire, and dangerous goods release, resulting in 30 scenarios analyzed using Event Tree Analysis (ETA). The model estimates fatalities considering train and tunnel
characteristics and assesses user evacuation feasibility via egress modeling. It employs results of 1D, zone, and 3D computational fluid dynamics (CFD) simulations to evaluate scenario dynamics and consequences. TRAM-R2 allows simulating scenarios for different tunnels, considering layout, infrastructure, equipment, and management impacts on egress and scenario propagation. It accounts for interdependent measures and their reliability during emergencies. The paper demonstrates TRAM-R2's application through case studies,
highlighting its potential for quantitative risk assessment in railway tunnels, facilitating comparison with regulatory criteria. Overall, TRAM-R2 provides a comprehensive tool for assessing and mitigating risks in rail tunnel operations, aiding compliance with safety standards and regulations
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