Numerical Study on the Kinetic Effects of Hydrogen Addition on the Thermal Characteristics of Laminar Methane Diffusion Flames

2018 ◽  
Vol 16 (8) ◽  
Author(s):  
Long Wu ◽  
Noriyuki Kobayashi ◽  
Zhanyong Li
Keyword(s):  
Heat Release ◽  
Diffusion Flames ◽  
Numerical Study ◽  
Combustion Process ◽  
Thermal Characteristics ◽  
Detailed Chemical Kinetics ◽  
Increase Rate ◽  
Methane Diffusion ◽  
Kinetic Effects ◽  
Detailed Chemical

Abstract The kinetic effects of H2 addition on the thermal characteristics of laminar methane diffusion flames were numerically studied using a detailed chemical kinetics consisting of 53 species and 325 reactions. The variations in the heat release properties and relevant key reactions with H2 addition were analyzed. Results show that the reactions of H + O2 + H2O ⇔ HO2 + H2O (R35), H + HO2 ⇔ OH + OH (R46), H + CH3 (+ M) ⇔ CH4 (+ M) (R52) and OH + H2 ⇔ H + H2O (R84) present important roles in the global heat release and the contributions of these reactions significantly increased as H2 is added to CH4 stream. Moreover, the increase rate of contribution of R84 with H2 addition is much larger than those of the reactions of R35, R46 and R52. The H and OH are the two most important radicals for heat release in the combustion process of CH4-H2 diffusion flame. The reaction of R84 is one of the main contributors for production of H radical and the contribution of R84 significantly increased with H2 addition, while the reaction of H + O2 ⇔ O + OH (R38) dominates the contribution of production of OH, which contributes more than 50 %, no matter whether H2 is added to CH4 stream.

PARALLEL SOLVER FOR THE SIMULATIONS OF DETONATION WAVES ON UNSTRUCTURED GRIDS

2020 ◽  
Author(s):  
A. I. Lopato ◽  
◽  
A. G. Eremenko ◽  
Keyword(s):  
Chemical Kinetics ◽  
Numerical Scheme ◽  
Unstructured Grids ◽  
Numerical Study ◽  
Numerical Approach ◽  
Detonation Waves ◽  
Detailed Chemical Kinetics ◽  
Parallel Solver ◽  
Further Development ◽  
Detailed Chemical

Recently, we developed a numerical approach for the simulation of detonation waves on fully unstructured grids and applied it to the numerical study of the mechanisms of detonation initiation in multifocusing systems. Current work is devoted to further development of our numerical approach, namely, parallelization of the numerical scheme and introduction of more comprehensive detailed chemical kinetics scheme.

scholarly journals The new design of the wood stove based on the numerical analysis and experimental research

2020 ◽  
Vol 154 ◽  
pp. 04001
Author(s):  
Przemysław Motyl ◽  
Marcin Wikło ◽  
Julita Bukalska ◽  
Bartosz Piechnik ◽  
Rafał Kalbarczyk
Keyword(s):  
Fluid Flow ◽  
Heat Exchange ◽  
Numerical Analysis ◽  
Heat Release ◽  
Experimental Research ◽  
Numerical Study ◽  
Combustion Process ◽  
Small Scale ◽  
Wood Stove ◽  
Wood Stoves

In Europe, especially in Poland, wood-fired stoves remain one of the most popular renewable household heating. The use of wood logs in small-scale units stoves are expected to increase substantially. The work proposes a comprehensive approach to modify the design of wood stoves with heating power up to 20 kW, including design works, simulations, and experimental research. The article also presents the numerical study of a combustion process including fluid flow, chemical combustion reaction, and heat exchange in the wood stove. The retrofit enhanced a more stable heat release from the wood stove, which increased efficiency and reduction of the harmful components of combustion.

Development of the Rate-Controlled Constrained-Equilibrium Method for Modeling of Ethanol Combustion

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Ghassan Nicolas ◽  
Hameed Metghalchi
Keyword(s):  
Ignition Delay ◽  
Stable Equilibrium ◽  
Combustion Process ◽  
Detailed Chemical Kinetics ◽  
Equilibrium Method ◽  
Constrained Equilibrium ◽  
Ethanol Combustion ◽  
Rate Controlled ◽  
Detailed Chemical

The rate-controlled constrained-equilibrium method (RCCE) has been further developed to model the combustion process of ethanol air mixtures. The RCCE is a reduction technique based on local maximization of entropy or minimization of a relevant free energy at any time during the nonequilibrium evolution of the system subject to a set of kinetic constraints. An important part of RCCE calculation is determination of a set of constraints that can guide the nonequilibrium mixture to the final stable equilibrium state. In this study, 16 constraints have been developed to model the nonequilibrium ethanol combustion process. The method requires solution of 16 differential equations for the corresponding constraint potentials. Ignition delay calculations of ethanol oxidizer mixtures using RCCE have been compared to those of detailed chemical kinetics using 37 species and 235 reactions. Agreement between the two models is very good. In addition, ignition delay of C2H5OH/O2/Ar mixtures using RCCE has been compared with the experimental measurements in the shock tube and excellent agreement has been reached validating the RCCE calculation.

Combustion Oscillations in Bluff Body Stabilized Diffusion Flames With Variable Length Inlet

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
M. Madanmohan ◽  
S. Pandey ◽  
A. Kushari ◽  
K. Ramamurthi
Keyword(s):  
Heat Release ◽  
Phase Angle ◽  
Bluff Body ◽  
Diffusion Flames ◽  
Combustion Process ◽  
Low Frequency ◽  
Pressure Oscillations ◽  
Pipe Length ◽  
Entry Length ◽  
Low Frequency Oscillations

This paper describes the results of an experimental study to understand the influence of inlet flow disturbances on the dynamics of combustion process in bluff body stabilized diffusion flames of liquid petroleum gas and air. The results show the influence of weak disturbances created by the change in incoming pipe length on the amplitude of pressure oscillations and the phase angle between pressure and heat release. It is seen that the phase delay increases as the entry length increases. The rms value of pressure, however, generally falls with the increase in length. The phase angle is seen to be in the second quadrant, showing that the heat release oscillations damp the pressure oscillations. Therefore, the decrease in the phase angle results in the reduction in damping and hence an increase in pressure fluctuations. The dominant frequencies of combustion oscillations are found to be the low frequency oscillations, and the frequency of oscillations increases with a decrease in the inlet pipe length and an increase in the flow Reynolds number. It is suggested that such low frequency oscillations are driven by vortex shedding at the wake of the bluff body, which energizes the diffusion and mixing process.

A Numerical Study of the Unsteady Effects of Droplet Evaporation and Ignition in Homogeneous Environments of Fuel and Air

1994 ◽  
Vol 116 (3) ◽  
pp. 194-200 ◽  
Author(s):  
P. Samuel ◽  
G. A. Karim
Keyword(s):  
Numerical Study ◽  
Reaction Rates ◽  
Detailed Chemical Kinetics ◽  
Surrounding Environment ◽  
Unsteady Effects ◽  
Combustion Processes ◽  
Effective Reaction ◽  
Detailed Chemical ◽  
Homogeneous Environment ◽  
Effective Reaction Rate

The transient processes of droplet heating, vaporization and ignition in a quiescent heated environment of a homogeneous mixture of air and fuel that is potentially combustible are analyzed. A system of partial differential equations that governs this hybrid diffusional-premixed processes is presented. The equations were solved numerically for an n-heptane droplet vaporizing in a homogeneous environment of methane and air. The effective reaction rate of the oxidation processes was assumed throughout to equal the sum of the reaction rates due to droplet and auxiliary fuels. The gross reaction rates used in the model for the droplet and auxiliary fuels were obtained from curve fitting of reaction rates results obtained from detailed chemical kinetics for the two fuels system. It is to be shown, for example, that the presence of an auxiliary fuel with the air in the surrounding environment of the droplet enhances the rates of the ignition/combustion processes of the droplet.

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