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Combustion of Heavy Hydrocarbons at Ultrahigh Pressure

#2255


Ignition and Combustion of Heavy Hydrocarbons at Ultrahigh Pressure: Detailed Kinetics of Process and Pollutants Formation

Tech Area / Field

  • CHE-THE/Physical and Theoretical Chemistry/Chemistry
  • NNE-FUE/Fuels/Non-Nuclear Energy

Status
3 Approved without Funding

Registration date
11.07.2001

Leading Institute
Moscow Institute of Physics and Technology, Russia, Moscow reg., Dolgoprudny

Supporting institutes

  • Makeyev Design Bureau of State Rocket Center, Russia, Chelyabinsk reg., Miass

Collaborators

  • Institut für Physikalische Chemie der Universität Göttingen, Germany, Göttingen\nVrije Universiteit Brussel, Belgium, Brussels\nGeneral Electric Company / Energy and Environmental Research Corporation, USA, CA, Irvine\nCatholic University of America, USA, DC, Washington\nCNRS / Laboratoire de Combustion et Systemes Reactifs, France, Orleans\nUniversity of Illinois, USA, IL, Chicago

Project summary

At present new strong limitations for minimal efficiency and ecological purity of the new gas-turbines, internal combustion engines and other combustion devices are under consideration. The main purpose of these limitations are the fuel consumption, emission of NOx and soot particles reduction, and increase the efficiency. To improve the efficiency of the fuel combustion and to reduce the emission of pollutants, it is necessary to be able to model the ignition and the oxidation of higher alcanes at high temperatures and pressures. Up to now, only a few detailed kinetic mechanisms were written for modeling the combustion of heavy hydrocarbons. There are two causes limiting the investigations. The first reason is an actual absence of information about the combustion dynamics at high pressure (from tens to hundreds atm). The second reason is the fact that at high enough temperatures and reagent concentrations characteristic time of reaction becomes comparable or shorter than time required for molecular internal energy distribution to reach its steady state. The kinetics of such elementary reactions is characterized by a complex time dependence controlled by interplay of formation, decay, and collisional relaxation/excitation processes, which determine the population of particular energy levels. Moreover, the kinetic peculiarities of the same species formed in different reactions can be different due to different internal energy distributions. Thus, the main gaps in the theory of combustion of heavy hydrocarbons are:

– Ultra high-pressure combustion regimes, where existing kinetic schemes can fail because of a changing the order of main reactions from low to high-pressure limit.

–· Combustion of the undiluted mixtures, where radical-radical reactions, activation of reagents, and non-equilibrium energy exchange can lead to alternative chains appearance and arising of the energetic back-coupling essentially changing the total combustion kinetic.

– Adaptive generation, analysis, and reduction of kinetic schemes of the heavy hydrocarbons combustion in a wide pressure and temperature range taking into account the mechanisms of nitric oxides formation.

The proposed research will be focused on the experimental and theoretical investigations that fill these gaps. The proposed project suggests an experimental investigation and numerical simulation of ignition development, flame propagation and combustion products for different hydrocarbon-air mixtures in a wide pressure and temperature range. The project fulfillment assume the further theory development of hydrocarbon pyrolysis and combustion, based on the experimental investigations and the numerical simulations.

In the framework of the project proposed the following researches will be performed:

– Experimental investigation of the combustion chemistry of methane, ethane, n-propane, n-pentane, n-hexane, n-heptane, n- octane, and n- decane by the use of a flow reactor at relatively low temperatures (900-1,900 K) and high pressures (1-100 atm). Concentrations of reagents, stable intermediates and resulting combustion products at the wide range of experimental conditions will be measured.

– Experimental investigation of the ignition and combustion of C1-C10 hydrocarbon-air mixtures under an independent variation of mixture composition (from 0 to stoichiometry), at pressure from 1 to 200 atm and temperature from 1,200 to 2,500 K using the reflected shock wave technique in a pre-heated shock tube; experimental investigation of the kinetics of reagents and products, rate constants of primary reactions.

– Experimental investigation of a hydrocarbons-NOx reaction in the flow reactor at temperatures up to 1,900 K and pressures up to 100 atm and in the shock tube at temperatures from 1,200 to 2,500 K and pressures up to 200 atm.

– Development and verification of the kinetic model that will be intended for describing the ignition and combustion of fuel-air mixtures under high pressures and temperatures. Determination of the main reaction stages through detailed comparison of calculations and experimental results. The role of non-equilibrium energy exchanges on the combustion kinetic will be determined in the wide range of parameters.

– The numerical algorithm development for automatic generation of kinetic models for describiption of the ignition and combustion of hydrocarbon-air mixtures with the specified detalisation degree under the temperature range from 800 to 2,500 K and pressures from 1 to 200 atm.

Applied significance of the project is the investigation of the ability of combustion processes optimization for hybrocarbon-air mixtures at high pressures. Such an improvement will be useful in design of up-to-date gas turbines, internal combustion engines, and other combustion devices.

The foreign collaborators are interested in both the fundamental and applied aspects of the project. The project corresponds to the ISTC objectives since there are participants from the State Rocket Center “Makeev Design Bureau”. The project involves the scientists connected with rocket weapon design into the peaceful activities.


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