The Combustion Numerical Simulation of a Liquid Slag Pulverized Coal Burner in the High Temperature Secondary Air

Taking a liquid slag pulverized coal burner as the research object, the combustion characteristics of the burner in different high temperature secondary air were simulated by Fluent commercial software, and the combustion characteristics of temperature field distribution and the change of component concentration were obtained. The simulation results show that the burner can form a front ignition zone, the air vortex low temperature zone, the central DC flame and the annular flame in the hot state. It can be found that increasing the secondary air temperature can improve the combustion intensity of the burner, promote the formation of CO, and form a high temperature reduction zone, which is conducive to inhibiting pollutant emissions. The research results provide theoretical support for the application of the burner in practice.

Defensible Spaces and Home Ignition Zones of Wildland-Urban Interfaces in the Fire-prone Areas of the World

Wildland-Urban Interfaces (W-UI) are at high risk of wildfires. Defensible spaces and home ignition zones are the two main aspects to protect lives and livelihoods of W-UI in the United States, Canada and Australia. The different part of the world has different rules and regulations for W-UI land management. We have discussed the defensible spaces in fire-prone areas, current ignition zone distances from structures, building materials, architectural design, the fire resistance trees, ground cover, landscaping and some other precautions to save lives and assets in the prominent fire-prone zones for three different countries (United States, Canada and Australia) of the world.

OPTIMIZATION OF IGNITION ZONE OF ADVANCED FAST REACTOR, WORKING IN NUCLEAR BURNING WAVE MODE

This article deals with the problem of optimizing composition and structure of the ignition zone of the fast reactor operating in the self-sustaining mode of nuclear burning wave with the purpose of its smooth start-up and reducing fissile material amount in initial assembly. The cylindrical homogeneous reactor with the ignition zone placed in the center or near the cylinder end is considered. The analysis has been performed basing on solving the non-stationary neutron diffusion equation together with the fuel burn-up equations and the equations of nuclear kinetics for precursor nuclei of delayed neutrons, with using the radial buckling approximation. An optimized structure of the ignition zone has been proposed, which ensures a smooth transition of the reactor to the self-sustaining nuclear burning wave mode, avoiding an excessive energy release, which is observed when using a simplified scheme of ignition zone. Comparison of the startup variants with the ignition zone at the cylinder end and at its center shows the benefits of the second one.

Defensible Spaces and Home Ignition Zones of Wildland-Urban Interfaces in the Fire-prone Areas of the World

Wildland-Urban Interfaces are in high risk of wildfires. Defensible spaces and home ignition zones are the two main aspects to protect lives and livelihoods of W-UI in the United States, Canada and Australia. Different part of the world has different rules and regulations for W-UI land management. We have discussed the defensible spaces in fire-prone areas, and current ignition zone distances with the fire resistance plant species to save lives and assets in the prominent fire-prone zones (United States, Canada and Australia) of the world.

Effect of Fuel Distribution on the Onset of Detonation in Gaseous Octane Air Mixture

Formation of detonation waves in a tube is a complex phenomenon and depends upon many factors like ignition energy, presence of a deflagration to detonation transition (DDT) enhancement device and spatial distribution of fuel, etc. In present study, gaseous octane-air mixtures have been examined by varying the equivalence ratio linearly along the axial direction of the detonation tube though the overall stoichiometry was maintained in the tube. Three different conditions have been modelled and studied, which includes small, moderate and large, fuel density gradient in axial direction with equivalence ratio ranging from 1 to 2 near the ignition zone. A series of simulation study have been conducted and the analysis of simulation results reveal that the DDT onset is significantly affected by the initial fuel distribution at the ignition zone as well as on fuel density gradient in a detonation tube. It has been observed thata moderate gradient in the fuel density distribution is favorable for onset of detonations. From the study of pressure plots for above mentioned conditions it has been found that the presence of large gradients in fuel density has adverse effect on the stability of detonation wave.

Study of the fire dynamics in a burning car and analysis of the possibilities for transfer of fire to a nearby vehicle

A full scale experiment was carried out on the process of vehicle combustion and the ignition of an adjacent one. For this purpose, specialized measuring equipment (thermocouples and infrared camera) is used to determine the temperature field of the burning car and nearby vehicle. The burning car has 16 thermocouples mounted on it and one thermocouple mounted on the adjacent car in order to examine the heat transfer process. The temperature field between cars at different points of time is detected by an infrared camera, with a clear change in the temperature gradient in the presence of wind. It is one of the main reasons for the increased momentum of heat transfer. The research shows that with the available combustible load of the car (2,1 MW or around the average for the currently produced cars), the ignition of the neighbouring vehicle is expected around 14 minutes after the ignition of the main vehicle, with the ignition zone being in the engine compartment. Important information was obtained for both the dynamics of the burning vehicle and the temperature field between the two cars.

Experimental study of chemiluminescence in UV and VIS range at hydrogen-oxygen mixtures ignition

The nonequilibrium radiation in the spectral range of 210-415 nm at ignition of a 10% stoichiometric hydrogen-oxygen mixture with additives of combustion inhibitors diluted with argon behind shock waves was registered. The detected chemiluminescence is presumably attributed to electronically excited H2O* and H2O2 *. Instead of the expected quenching of excited radicals and molecules in the ignition zone, with the addition of halogenated hydrocarbons inhibitors, the increase of radiation, particularly in the range of 330-415 nm, was observed. The possible reasons of this phenomenon are discussed.

Numerical Study of Heat and Mass Transfer at the Ignition of Condensed Substances by Hot Particles

Mathematical models of ignition of condensed substances considering interconnected processes of a heat and mass transfer in systems “composite propellant – hot particle – gas”, “liquid fuel – hot particle – air” and “gel-like fuel – hot particle – gas” were developed. As a result of numerical modeling modes of ignition for solid, liquid and gel-like condensed substances characterized by ignition delay time and arrangement of ignition zone relative to local energy source were established. Liquid fuel has 3 ignition modes, composite propellant and gel-like fuels have 1 ignition mode

Preliminary Core Design and Optimization Analysis of Travelling Wave Reactor

A travelling wave reactor (TWR) is an advanced nuclear reactor which is capable of running for decades given only depleted uranium fuel, it is considered one of the most promising solutions for nonproliferation. A preliminary core design was proposed in this paper. The calculation was performed by Monte Carlo method. The burning mechanism of the reactor core design was studied. Optimization on the ignition zone was performed to reduce the amount of enriched uranium initially deployed. The results showed that the preliminary core design was feasible. The optimization analysis showed that the amount of enriched uranium could be reduced under rational design.