STUDY OF GAS FUEL LEAKAGE AND EXPLOSION IN THE ENGINE ROOM OF A SMALL LNG-FUELED SHIP

The engine fuel piping in LNG-fuelled ships’ engine room presents potential gas explosion risks due to possible gas fuel leakage and dispersion. A 3D CFD model with chemical reaction was described, validated and then used to simulate the possible gas dispersion and the consequent explosions in an engine room with regulations commanded ventilations. The results show that, with the given minor leaking of a fuel pipe, no more than 1kg of methane would accumulate in the engine room. The flammable gas clouds only exit in limited region and could lead to explosions with an overpressure about 12 mbar, presenting no injury risk to personnel. With the given major leaking, large region in the engine room would be filled with flammable gas cloud within tens of seconds. The gas cloud might lead to an explosion pressure of about 1 bar or higher, which might result in serious casualties in the engine room.

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Intelligent Mobile Wireless Network for Toxic Gas Cloud Monitoring and Tracking

Sensors ◽

10.3390/s21113625 ◽

2021 ◽

Vol 21 (11) ◽

pp. 3625

Author(s):

Mateusz Krzysztoń ◽

Ewa Niewiadomska-Szynkiewicz

Keyword(s):

Data Exchange ◽

Mobility Model ◽

Model Parameters ◽

Toxic Substances ◽

Cloud Detection ◽

Gas Dispersion ◽

Gas Concentration ◽

Cloud Monitoring ◽

Optimal Values ◽

Gas Cloud

Intelligent wireless networks that comprise self-organizing autonomous vehicles equipped with punctual sensors and radio modules support many hostile and harsh environment monitoring systems. This work’s contribution shows the benefits of applying such networks to estimate clouds’ boundaries created by hazardous toxic substances heavier than air when accidentally released into the atmosphere. The paper addresses issues concerning sensing networks’ design, focussing on a computing scheme for online motion trajectory calculation and data exchange. A three-stage approach that incorporates three algorithms for sensing devices’ displacement calculation in a collaborative network according to the current task, namely exploration and gas cloud detection, boundary detection and estimation, and tracking the evolving cloud, is presented. A network connectivity-maintaining virtual force mobility model is used to calculate subsequent sensor positions, and multi-hop communication is used for data exchange. The main focus is on the efficient tracking of the cloud boundary. The proposed sensing scheme is sensitive to crucial mobility model parameters. The paper presents five procedures for calculating the optimal values of these parameters. In contrast to widely used techniques, the presented approach to gas cloud monitoring does not calculate sensors’ displacements based on exact values of gas concentration and concentration gradients. The sensor readings are reduced to two values: the gas concentration below or greater than the safe value. The utility and efficiency of the presented method were justified through extensive simulations, giving encouraging results. The test cases were carried out on several scenarios with regular and irregular shapes of clouds generated using a widely used box model that describes the heavy gas dispersion in the atmospheric air. The simulation results demonstrate that using only a rough measurement indicating that the threshold concentration value was exceeded can detect and efficiently track a gas cloud boundary. This makes the sensing system less sensitive to the quality of the gas concentration measurement. Thus, it can be easily used to detect real phenomena. Significant results are recommendations on selecting procedures for computing mobility model parameters while tracking clouds with different shapes and determining optimal values of these parameters in convex and nonconvex cloud boundaries.

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A New Gas Turbine Enclosure Ventilation Design Criterion

Volume 5: Turbo Expo 2005 ◽

10.1115/gt2005-68725 ◽

2005 ◽

Author(s):

Roger C. Santon ◽

Matthew J. Ivings ◽

David K. Pritchard

Keyword(s):

Gas Turbine ◽

Design Criterion ◽

Cfd Modelling ◽

Safety Criterion ◽

Flammable Gas ◽

Computational Fluid Dynamics Cfd ◽

Acoustic Enclosures ◽

New Criterion ◽

Gas Cloud ◽

Flammable Gas Cloud

Dilution ventilation is a widely used means of protection against the risk of explosion within gas turbine acoustic enclosures arising from the leakage and accumulation of flammable gas and its ignition from the turbine. In ASME 98GT-215 a safety criterion was proposed for the design of ventilation by defining the allowable size of flammable gas cloud as a proportion of the enclosure volume. This criterion was theoretically based, with a significant safety factor. Whilst generally viable, it was found to be difficult to achieve in some cases. A research project, described in ASME GT-2002-30469, was launched to define a criterion more accurately and with known conservatism based on a detailed programme of experimental explosions and Computational Fluid Dynamics (CFD) modelling. The $600k project was largely financed by the gas turbine industry, including suppliers and users, and by CFD contractors. The paper describes the project aims, its scope of work, and includes the main results, the new criterion and conclusions.

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Explosion Characteristics of Hydrogen for CFD Modelling and Simulation of Turbulent Gas Flow

MATEC Web of Conferences ◽

10.1051/matecconf/201816807013 ◽

2018 ◽

Vol 168 ◽

pp. 07013 ◽

Cited By ~ 1

Author(s):

Jan Skřínský ◽

Jan Koloničný ◽

Tadeáš Ochodek

Keyword(s):

Energy Demand ◽

Gas Flow ◽

Hydrogen Gas ◽

Absolute Pressure ◽

Gas Explosion ◽

Cfd Modelling ◽

Gas Dispersion ◽

Turbulent Gas Flow ◽

Gas Cloud ◽

Chamber Gas

Renewable energies became more and more important in the last years. Hydrogen as a promising energy carrier is a perfect candidate to supply the energy demand of the world. The state of the hydrogen gas (turbulences and point concentrations) has a significant impact on the gas explosion indices. A gas cloud is formed by a partial-pressure method in gas explosion experiments in the spherical 20.0∙10-3 m3 chamber. Gas in the chamber reaches an uniform state beyond in hundreds of ms. The absolute pressure for gas dispersion should be higher than 0.01 MPa for the H2 of concentration larger than 30 vol. % of fuel. The initial temperature also influences turbulent gas flow before ignition, especially in the case of the gases lighter-than-air.

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Modeling and analysis of flammable gas dispersion and deflagration from offshore platform blowout

Ocean Engineering ◽

10.1016/j.oceaneng.2020.107146 ◽

2020 ◽

Vol 201 ◽

pp. 107146 ◽

Cited By ~ 4

Author(s):

Xinhong Li ◽

Rouzbeh Abbassi ◽

Guoming Chen ◽

Qingsheng Wang

Keyword(s):

Offshore Platform ◽

Modeling And Analysis ◽

Gas Dispersion ◽

Flammable Gas

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Modelling of Heavy Flammable Gas Dispersion with FDS5

Proceedings of the Sixth International Seminar on Fire and Explosion Hazards ◽

10.3850/978-981-08-7724-8_16-02 ◽

2011 ◽

Author(s):

Cocchi G.

Keyword(s):

Gas Dispersion ◽

Flammable Gas

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CALCULATING SPECIFIC HEAT OF COMBUSTION PRODUCTS IN GAS MODE DIESEL ENGINES

VESTNIK OF ASTRAKHAN STATE TECHNICAL UNIVERSITY SERIES MARINE ENGINEERING AND TECHNOLOGIES ◽

10.24143/2073-1574-2019-2-48-55 ◽

2019 ◽

pp. 48-55

Author(s):

Anatoliy Nickolaevich Sobolenko

Keyword(s):

Heat Capacity ◽

Natural Gas ◽

Specific Heat ◽

Diesel Engines ◽

Combustion Products ◽

Engine Fuel ◽

Gas Engine ◽

Fishing Vessels ◽

Gas Fuel ◽

Clean Combustion

The task of using natural gas-engine fuel in transport diesel engines (marine and automobile) is very actual. The trends of converting diesel engines to gas mode on ships of the port fleet and fishing vessels are becoming widespread. The importance to clarify the calculation methods of the working process for gas mode diesel engines is growing. Natural gas has been stated to comprise different gases - methane, ethane, propane, butane, carbon monoxide, etc., the percentage correlations of which being presented. There has been studied the method of calculating heat capacity of “pure” combustion products, i.e. under fuel combustion with excessive air coefficient α =1. The chemical reactions of oxidation elements of gas fuel components during its combustion determine the amount of kilomole of combustion products. To determine the heat capacity of the components of the combustion products - CO2, H2O and N2, the known tables of gases and water vapor properties were used. As a result of data processing, approximating linear and quadratic dependences were obtained. Нeat capacities are calculated in the linear formula of the specific heat of “pure” combustion products as the heat capacity of the gas mixture. As a result, a formula for determining the heat capacity of “clean” combustion products of gas fuel has been obtained: CVG = 25.03 + 0.0065· T . For determining the heat capacity of “clean” combustion products of gas fuel with 10% additive of ignition diesel fuel the formula has the following form CVGZH = 24.57 + 0.006· T . The dependences obtained are fairly accurate and recommended for using in the practice of converting diesel engines to gas-engine fuel, as well as when carrying out works and watercraft technology in building the ships and water transport.

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Based on minimum fuel consumption mode integrated optimal control of fixed-wing UAV flight propulsion system

Aircraft Engineering and Aerospace Technology ◽

10.1108/aeat-09-2020-0211 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Yong Li ◽

Feifei Han ◽

Xinzhe Zhang ◽

Kai Peng ◽

Li Dang

Keyword(s):

Optimal Control ◽

Real Time ◽

Fuel Consumption ◽

Control Method ◽

Reference Model ◽

Pressure Ratio ◽

Engine Fuel ◽

Content Type ◽

Optimization Control ◽

The Given

Purpose In this paper, with the goal of reducing the fuel consumption of UAV, the engine performance optimization is studied and on the basis of aircraft/engine integrated control, the minimum fuel consumption optimization method of engine given thrust is proposed. In the case of keeping the given thrust of the engine unchanged, the main fuel flow of the engine without being connected to the afterburner is optimally controlled so as to minimize the fuel consumption. Design/methodology/approach In this study, the reference model real-time optimization control method is adopted. The engine reference model uses a nonlinear real-time mathematical model of a certain engine component method. The quasi-Newton method is adopted in the optimization algorithm. According to the optimization variable nozzle area, the turbine drop-pressure ratio corresponding to the optimized nozzle area is calculated, which is superimposed with the difference of the drop-pressure ratio of the conventional control plan and output to the conventional nozzle controller of the engine. The nozzle area is controlled by the conventional nozzle controller. Findings The engine real-time minimum fuel consumption optimization control method studied in this study can significantly reduce the engine fuel consumption rate under a given thrust. At the work point, this is a low-altitude large Mach work point, which is relatively close to the edge of the flight envelope. Before turning on the optimization controller, the fuel consumption is 0.8124 kg/s. After turning on the optimization controller, you can see that the fuel supply has decreased by about 4%. At this time, the speed of the high-pressure rotor is about 94% and the temperature after the turbine can remain stable all the time. Practical implications The optimal control method of minimum fuel consumption for the given thrust of UAV is proposed in this paper and the optimal control is carried out for the nozzle area of the engine. At the same time, a method is proposed to indirectly control the nozzle area by changing the turbine pressure ratio. The relevant UAV and its power plant designers and developers may consider the results of this study to reach a feasible solution to reduce the fuel consumption of UAV. Originality/value Fuel consumption optimization can save fuel consumption during aircraft cruising, increase the economy of commercial aircraft and improve the combat radius of military aircraft. With the increasingly wide application of UAVs in military and civilian fields, the demand for energy-saving and emission reduction will promote the UAV industry to improve the awareness of environmental protection and reduce the cost of UAV use and operation.

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