Accounting for complex chemistry in the simulations of future turbulent combustion systems

2019 ◽  
Author(s):  
Benoit Fiorina
Keyword(s):  
Turbulent Combustion ◽  
Combustion Systems ◽  
Complex Chemistry

scholarly journals Numerical Predictions of a Swirl Combustor Using Complex Chemistry Fueled with Ammonia/Hydrogen Blends

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 288 ◽  
Author(s):  
Marco-Osvaldo Vigueras-Zuniga ◽  
Maria-Elena Tejeda-del-Cueto ◽  
José-Alejandro Vasquez-Santacruz ◽  
Agustín-Leobardo Herrera-May ◽  
Agustin Valera-Medina
Keyword(s):  
Boundary Conditions ◽  
High Pressures ◽  
Numerical Study ◽  
High Energy ◽  
Combustion Efficiency ◽  
Heat Losses ◽  
High Hydrogen ◽  
Numerical Predictions ◽  
Combustion Systems ◽  
Complex Chemistry

Ammonia, a chemical that contains high hydrogen quantities, has been presented as a candidate for the production of clean power generation and aerospace propulsion. Although ammonia can deliver more hydrogen per unit volume than liquid hydrogen itself, the use of ammonia in combustion systems comes with the detrimental production of nitrogen oxides, which are emissions that have up to 300 times the greenhouse potential of carbon dioxide. This factor, combined with the lower energy density of ammonia, makes new studies crucial to enable the use of the molecule through methods that reduce emissions whilst ensuring that enough power is produced to support high-energy intensive applications. Thus, this paper presents a numerical study based on the use of novel reaction models employed to characterize ammonia combustion systems. The models are used to obtain Reynolds Averaged Navier-Stokes (RANS) simulations via Star-CCM+ with complex chemistry of a 70%–30% (mol) ammonia–hydrogen blend that is currently under investigations elsewhere. A fixed equivalence ratio (1.2), medium swirl (0.8), and confined conditions are employed to determine the flame and species propagation at various operating atmospheres and temperature inlet values. The study is then expanded to high inlet temperatures, high pressures, and high flowrates at different confinement boundary conditions. The results denote how the production of NOx emissions remains stable and under 400 ppm, whilst higher concentrations of both hydrogen and unreacted ammonia are found in the flue gases under high power conditions. The reduction of heat losses (thus higher temperature boundary conditions) has a crucial impact on further destruction of ammonia post-flame, with a raise in hydrogen, water, and nitrogen through the system, thus presenting an opportunity of combustion efficiency improvement of this blend by reducing heat losses. Final discussions are presented as a method to raise power whilst employing ammonia for gas turbine systems.

scholarly journals Entropy Transport Equation in Large Eddy Simulation for Exergy Analysis of Turbulent Combustion Systems

Entropy ◽  
2010 ◽  
Vol 12 (3) ◽  
pp. 434-444 ◽  
Author(s):  
Mehdi Safari ◽  
M. Reza H. Sheikhi ◽  
Mohammad Janbozorgi ◽  
Hameed Metghalchi
Keyword(s):  
Large Eddy Simulation ◽  
Transport Equation ◽  
Turbulent Combustion ◽  
Exergy Analysis ◽  
Eddy Simulation ◽  
Entropy Transport ◽  
Large Eddy ◽  
Combustion Systems

Prediction of Local Entropy Generation in Turbulent Combustion Systems

2013 ◽  
Author(s):  
Mehdi Safari ◽  
M. Reza H. Sheikhi
Keyword(s):  
Entropy Generation ◽  
Turbulent Combustion ◽  
Effective Means ◽  
Turbulent Flames ◽  
Turbulent Reacting Flows ◽  
Local Entropy ◽  
Filtered Density Function ◽  
Eddy Simulation ◽  
Combustion Systems ◽  
Local Entropy Generation

Analysis of local entropy generation or exergy destruction is an effective means to investigate sources of efficiency loss to optimize the performance of energy and combustion systems. The local entropy production is predicted using large eddy simulation of turbulent reacting flows. The unclosed entropy generation effects are accounted for by a novel methodology developed based on the filtered density function to embed the transport of entropy. Simulations are conducted of turbulent flames and predictions are validated via experimental data. Sources of irreversibility in turbulent combustion including viscous dissipation, heat conduction, mass diffusion and chemical reaction are predicted and analyzed. The influence of various operating parameters on local entropy generation and the exergetic efficiency of the combustion system is studied.

Sign in / Sign up

Export Citation Format

Share Document