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Pulsating Combustion - Combustion Characteristics and Reduction of Emissions

Lindholm, Annika LU (1999)
Abstract
In the search for high efficiency combustion systems pulsating combustion has been identified as one of the technologies that potentially can meet the objectives of clean combustion and good fuel economy.Pulsating combustion offers low emissions of pollutants, high heat transfer and efficient combustion. Although it is an old technology, the interest in pulsating combustion has been renewed in recent years, due to its unique features. Various applications of pulsating combustion can be found, mainly as drying and heating devices, of which the latter also have had commercial success. It is, however, in the design process of a pulse combustor, difficult to predict the operating frequency, the heat release etc., due to the lack of a well... (More)
In the search for high efficiency combustion systems pulsating combustion has been identified as one of the technologies that potentially can meet the objectives of clean combustion and good fuel economy.Pulsating combustion offers low emissions of pollutants, high heat transfer and efficient combustion. Although it is an old technology, the interest in pulsating combustion has been renewed in recent years, due to its unique features. Various applications of pulsating combustion can be found, mainly as drying and heating devices, of which the latter also have had commercial success. It is, however, in the design process of a pulse combustor, difficult to predict the operating frequency, the heat release etc., due to the lack of a well founded theory of the phenomenon.



Research concerning control over the combustion process is essential for developing high efficiency pulse combustors with low emissions. Natural gas fired Helmholtz type pulse combustors have been the experimental objects of this study. In order to investigate the interaction between the fluid dynamics and the chemistry in pulse combustors, laser based measuring techniques as well as other conventional measuring techniques have been used. The experimental results shows the possibilities to control the combustion characteristics of pulsating combustion. It is shown that the time scales in the large vortices created at the inlet to the combustion chamber are very important for the operation of the pulse combustor. By increasing/decreasing the time scale for the large scale mixing the timing of the heat release is changed and the operating characteristics of the pulse combustor changes.



Three different means for NOx reduction in Helmholtz type pulse combustors have been investigated. These include exhaust gas recirculation, alteration of air/fuel ratio and changed inlet geometry in the combustion chamber. All used methods achieved less than 10 ppm NOx emitted (referred to stoichiometric conditions).



Results from a 3D-LES simulation model for chemically reacting flows have been validated using the experimental data obtained within this study. The simulations have been carried out at the Division of Combustion Physics. The 3D simulation model can be used as a tool for studying the complex phenomena encountered in pulsating combustion. Together with measurements of temperature fields and measurements of the concentration of different species (for example O2, NO and CH4) in the combustion chamber, even further enhanced understanding of the fundamental processes in pulse combustors can be achieved. (Less)
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author
opponent
  • Professor Hustad, Johan E., Institute of Thermal Energy and Hydropower, NTNU, Norway
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Exhaust gas recirculation, NOx, Heat Release, Combustion related radicals, Laser based measurements, Pulsating Combustion, Unsteday Flow, Emissions, Combustion, Energy research, Energiforskning
pages
116 pages
publisher
Division of Energy Economics and Planning, Department of Heat and Power Engineering, Lund University
defense location
M:B, M-huset
defense date
1999-12-03 13:15
external identifiers
  • other:ISRN: LUTMDN/TMVK-1016-SE
ISSN
0282-1990
ISBN
91-7874-027-4
language
English
LU publication?
yes
id
c2077d8c-0c18-4712-981e-c84898b9b0fb (old id 40120)
date added to LUP
2007-07-31 16:03:09
date last changed
2016-09-19 08:44:56
@phdthesis{c2077d8c-0c18-4712-981e-c84898b9b0fb,
  abstract     = {In the search for high efficiency combustion systems pulsating combustion has been identified as one of the technologies that potentially can meet the objectives of clean combustion and good fuel economy.Pulsating combustion offers low emissions of pollutants, high heat transfer and efficient combustion. Although it is an old technology, the interest in pulsating combustion has been renewed in recent years, due to its unique features. Various applications of pulsating combustion can be found, mainly as drying and heating devices, of which the latter also have had commercial success. It is, however, in the design process of a pulse combustor, difficult to predict the operating frequency, the heat release etc., due to the lack of a well founded theory of the phenomenon.<br/><br>
<br/><br>
Research concerning control over the combustion process is essential for developing high efficiency pulse combustors with low emissions. Natural gas fired Helmholtz type pulse combustors have been the experimental objects of this study. In order to investigate the interaction between the fluid dynamics and the chemistry in pulse combustors, laser based measuring techniques as well as other conventional measuring techniques have been used. The experimental results shows the possibilities to control the combustion characteristics of pulsating combustion. It is shown that the time scales in the large vortices created at the inlet to the combustion chamber are very important for the operation of the pulse combustor. By increasing/decreasing the time scale for the large scale mixing the timing of the heat release is changed and the operating characteristics of the pulse combustor changes.<br/><br>
<br/><br>
Three different means for NOx reduction in Helmholtz type pulse combustors have been investigated. These include exhaust gas recirculation, alteration of air/fuel ratio and changed inlet geometry in the combustion chamber. All used methods achieved less than 10 ppm NOx emitted (referred to stoichiometric conditions).<br/><br>
<br/><br>
Results from a 3D-LES simulation model for chemically reacting flows have been validated using the experimental data obtained within this study. The simulations have been carried out at the Division of Combustion Physics. The 3D simulation model can be used as a tool for studying the complex phenomena encountered in pulsating combustion. Together with measurements of temperature fields and measurements of the concentration of different species (for example O2, NO and CH4) in the combustion chamber, even further enhanced understanding of the fundamental processes in pulse combustors can be achieved.},
  author       = {Lindholm, Annika},
  isbn         = {91-7874-027-4},
  issn         = {0282-1990},
  keyword      = {Exhaust gas recirculation,NOx,Heat Release,Combustion related radicals,Laser based measurements,Pulsating Combustion,Unsteday Flow,Emissions,Combustion,Energy research,Energiforskning},
  language     = {eng},
  pages        = {116},
  publisher    = {Division of Energy Economics and Planning, Department of Heat and Power Engineering, Lund University},
  school       = {Lund University},
  title        = {Pulsating Combustion - Combustion Characteristics and Reduction of Emissions},
  year         = {1999},
}