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You searched for subject:(porous burners). Showing records 1 – 3 of 3 total matches.

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University of Adelaide

1. Afsharvahid, Shahrooz. Nitrogen oxides reduction in a porous burner.

Degree: 2016, University of Adelaide

Different aspects of porous burners have been studied in the past in terms of the bed material, design, heat transfer modes and flame characteristics. However, the application of porous burners to NOx reduction and the effect of the bed surface on the chemical reactions have not yet been explored. Hence, the objective of this study is to investigate the effect of the design and operating parameters on NOx reduction inside a porous burner. To achieve this objective, a variety of flames, stabilised inside porous burners, were investigated experimentally, utilizing thermocouples, gas sampling and chromatography. Numerical tools were also used to understand the chemical pathways under different operating conditions better. Premixed CNG-air and LPG-air flames at very low equivalence ratios were stabilised inside the porous bed. The relationship between the volumetric flow rate of the mixture and the minimum equivalence ratio was studied (experimentally and numerically) for equivalence ratios as low as φ=0.35 (equivalent to thermal power of 2kW). The maximum temperature observed to be consistent with super-adiabatic flame temperatures. The maximum measured NOX and CO mole fractions at the burner exit were found to be in the order of few PPMs. The conversion of NOx was then assessed. A mixture of CNG-air doped with NO was introduced into the burner inlet and the effects of the operating parameters on NOx reduction were assessed. It was found that NOx reduction is a function of the equivalence ratio, total flow rate and NO mole fraction at the inlet. Higher flow rates led to an increase in the conversion rate at higher equivalence ratios, due to shorter residence times, and the greater need for more flame radicals in the flame. The numerical study revealed that different chemical pathways dominate at different equivalence ratios, which led to the production of other intermediates and stable radicals. The study showed that the Total Fixed Nitrogen, TFN, reduction followed a similar trend to the NOx reduction for moderately fuel-rich conditions (φ ≤ 1.2) and opposite trends for higher equivalence ratios. For φ>1.2, most of the NO is converted to N-containing species such as N₂O, NH₃ and HCN and not to N₂. Analysis of the chemical pathways showed that the formation of nitrogen-containing species under very fuel rich conditions is due to the increased importance of the HCNO path, as compared with the HNO path. The best TFN conversion efficiency, 65%, was found at φ=1.1. Intermediate radicals have different rates of destruction and production on the porous bed surface, especially for mixtures close to stoichiometric conditions. Under these conditions, the conversion of NOX is strongly influenced by the concentration of H radicals. A collision probability of η = 8 x 10⁻⁴ was found to represent this radical loss effect and to help predict the destruction and production of intermediate terminals with a good level of accuracy. This study also found that NOx reductions using porous burners are technically feasible and that the… Advisors/Committee Members: Dally, Bassam B. (advisor), School of Mechanical Engineering (school).

Subjects/Keywords: NOx reduction; porous burners; surface reaction; porous media

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Afsharvahid, S. (2016). Nitrogen oxides reduction in a porous burner. (Thesis). University of Adelaide. Retrieved from http://hdl.handle.net/2440/105979

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Afsharvahid, Shahrooz. “Nitrogen oxides reduction in a porous burner.” 2016. Thesis, University of Adelaide. Accessed June 24, 2019. http://hdl.handle.net/2440/105979.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Afsharvahid, Shahrooz. “Nitrogen oxides reduction in a porous burner.” 2016. Web. 24 Jun 2019.

Vancouver:

Afsharvahid S. Nitrogen oxides reduction in a porous burner. [Internet] [Thesis]. University of Adelaide; 2016. [cited 2019 Jun 24]. Available from: http://hdl.handle.net/2440/105979.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Afsharvahid S. Nitrogen oxides reduction in a porous burner. [Thesis]. University of Adelaide; 2016. Available from: http://hdl.handle.net/2440/105979

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Universidade do Rio Grande do Sul

2. Roldo, Ismael. Estudo experimental e teórico de chamas em escoamento de estagnação imersas em meios porosos inertes.

Degree: 2015, Universidade do Rio Grande do Sul

O interesse no desenvolvimento de sistemas eficientes de combustão para reduzir a poluição ambiental e aumentar a eficiência de queima tem chamado a atenção para a combustão em meios porosos inertes. A recirculação de calor, induzida pela matriz sólida a partir dos produtos quentes para os reagentes frios, aumenta a temperatura da chama melhorando a sua estabilidade e permitindo a utilização de combustíveis com baixo poder calorífico. Um estudo teórico recente mostra que uma chama estabilizada por um plano de estagnação imersa em um meio poroso pode, sob certas condições, estender os limites de inflamabilidade de uma mistura de ar e combustível. Por outro lado, o plano de estagnação é um problema que simula o efeito da taxa de deformação do escoamento sobre a estabilidade da chama, o que é relevante para várias configurações de queimador poroso. Portanto, o foco deste trabalho é o estudo da combustão em um queimador poroso com um plano de estagnação. Um experimento é conduzido com empacotamento de esferas, onde uma chama pode ser estabilizada por plano de estagnação devido a um anteparo. A razão de equivalência e a taxa de deformação são controladas pelos fluxos de ar e de combustível e da distância entre injetor e anteparo. A posição da chama é aproximadamente determinada pelo campo de temperaturas medidas por termopares. Complementarmente é realizada uma análise numérica simplificada do problema na qual se pode verificar o efeito da taxa de deformação sobre a estabilidade de chamas em queimadores porosos. Os resultados mostram que é possível estabilizar chamas no interior do meio poroso com plano de estagnação, porém, não foi possível atribuir um aumento de temperatura devido ao aumento da taxa de deformação.

The interest in developing efficient combustion systems to reduce environmental pollution and increase the burning efficiency has called attention to the combustion in inert porous media. The heat recirculation, induced by the solid matrix, from the hot products to the incoming cold reactants, increases the flame temperature and improves its stability, allowing for the use of fuels with low heat content. A recent study shows theoretically that a flame stabilized by a stagnation plane immersed in a porous medium may, under certain conditions, to extend the flammability limits of a mixture of fuel and air. On the other hand, the stagnation plane imposes a certain strain rate on the flow field, which is relevant to various porous burner configurations. Therefore, the focus of this work is the study of combustion in a porous burner with a stagnation plane. An experiment is conducted with packing bed of spheres where a flame can be stabilized against a stagnation plane. The equivalence ratio and the strain rate are controlled by the flows of air and fuel and the distance between the injector and the stagnation plane. The flame position is approximately determined by the temperature field measured by thermocouples. In addition, it is performed a simplified numerical analysis of the problem in which one can see…

Advisors/Committee Members: Pereira, Fernando Marcelo.

Subjects/Keywords: Combustão; Porous burners; Meios porosos; Premixed flame; Escoamento; Stretched flame; Simulação numérica

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Roldo, I. (2015). Estudo experimental e teórico de chamas em escoamento de estagnação imersas em meios porosos inertes. (Thesis). Universidade do Rio Grande do Sul. Retrieved from http://hdl.handle.net/10183/127905

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Roldo, Ismael. “Estudo experimental e teórico de chamas em escoamento de estagnação imersas em meios porosos inertes.” 2015. Thesis, Universidade do Rio Grande do Sul. Accessed June 24, 2019. http://hdl.handle.net/10183/127905.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Roldo, Ismael. “Estudo experimental e teórico de chamas em escoamento de estagnação imersas em meios porosos inertes.” 2015. Web. 24 Jun 2019.

Vancouver:

Roldo I. Estudo experimental e teórico de chamas em escoamento de estagnação imersas em meios porosos inertes. [Internet] [Thesis]. Universidade do Rio Grande do Sul; 2015. [cited 2019 Jun 24]. Available from: http://hdl.handle.net/10183/127905.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Roldo I. Estudo experimental e teórico de chamas em escoamento de estagnação imersas em meios porosos inertes. [Thesis]. Universidade do Rio Grande do Sul; 2015. Available from: http://hdl.handle.net/10183/127905

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Sydney

3. Wood, Susie. Ultra-lean methane combustion in porous burners .

Degree: 2010, University of Sydney

Ultra-lean methane combustion in porous burners is investigated by means of a pilot-scale demonstration of the technology supported by a computational fluid dynamics (CFD) modelling study. The suitability of porous burners as a lean-burn technology for the mitigation of methane emissions is also evaluated. Methane constitutes 14.3% of total global anthropogenic greenhouse gas emissions. The mitigation of these emissions could have a significant near-term effect on slowing global warming, and recovering and burning the methane would allow a wasted energy resource to be exploited. The typically low and fluctuating energy content of the emission streams makes combustion difficult; however porous burners—an advanced combustion technology capable of burning low-calorific value fuels below the conventional flammability limit—are a possible mitigation solution. A pilot-scale porous burner is designed expressly for the purpose of ultra-lean methane combustion. The burner comprises a cylindrical combustion chamber filled with a porous bed of alumina saddles, combined with an arrangement of heat exchanger tubes for preheating the incoming methane/air mixture. A CFD model is developed to aid in the design process. Results illustrating the operating range and behaviour of the burner are presented. Running on natural gas, the stable lean flammability limit of the system is 2.3 vol%, a considerable extension of the conventional lean limit of 4.3 vol%; operating in the transient combustion regime allows the lean limit to be reduced further still, to 1.1 vol%. The heat exchanger arrangement is found to be effective; preheat temperatures of up to 800K are recorded. Emissions of carbon monoxide and unburned hydrocarbons are negligible. The process appears stable to fluctuations in fuel concentration and flow rate, typically taking several hours to react to any changes. A CFD model of the porous burner is developed based on the commercial CFD code ANSYS CFX 12.0. The burner is modelled as a single 1-dimensional porous domain. Pressure loss due to the presence of the porous solid is accounted for using an isotropic loss model. Separate energy equations for the gas and solid phases are applied. Models for conductive heat transfer within the solid phase, and for convective heat transport between the gas and solid phases, are added. Combustion is modelled using a finite rate chemistry model; a skeletal mechanism for ultra-lean methane combustion is developed and incorporated into the model to describe the combustion reaction. Results from the model are presented and validated against experimental data; the model correctly predicts the main features of burner behaviour. Porous burners are found to show potential as a methane mitigation technology.

Subjects/Keywords: porous burners; ultra-lean methane combustion; mitigation of methane emissions; burner design; skeletal methane combustion mechanism; compuational fluid dynamics (CFD)

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Wood, S. (2010). Ultra-lean methane combustion in porous burners . (Thesis). University of Sydney. Retrieved from http://hdl.handle.net/2123/5956

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Wood, Susie. “Ultra-lean methane combustion in porous burners .” 2010. Thesis, University of Sydney. Accessed June 24, 2019. http://hdl.handle.net/2123/5956.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Wood, Susie. “Ultra-lean methane combustion in porous burners .” 2010. Web. 24 Jun 2019.

Vancouver:

Wood S. Ultra-lean methane combustion in porous burners . [Internet] [Thesis]. University of Sydney; 2010. [cited 2019 Jun 24]. Available from: http://hdl.handle.net/2123/5956.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Wood S. Ultra-lean methane combustion in porous burners . [Thesis]. University of Sydney; 2010. Available from: http://hdl.handle.net/2123/5956

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.