The effect of different alcohol fuels on the performance, emission and combustion characteristics of a gasoline engine

CATEGORY: COMBUSTION
Fuel, Volume 115, January 2014, Pages 901–906
The effect of different alcohol fuels on the performance, emission and combustion characteristics of a gasoline engine
Mustafa Kemal Balki (a), Cenk Sayin (b), Mustafa Canakci (c),  (d)
a Department of Mechanical & Metal Technology, Sinop University, Sinop 57030, Turkey
b Department of Mechanical Engineering, Marmara University, Istanbul 34722, Turkey
c Department of Automotive Engineering, Kocaeli University, Izmit 41380, Turkey
d Alternative Fuels R&D Center, Kocaeli University, Izmit 41275, Turkey
Abstract
Reports results of a study of the effect of alcohol in the form of ethanol and methanol on the performance, emissions and combustion characteristics of a low power single-cylinder engine. Researchers compared results with conventional gasoline operation.
Tests were performed at full-throttle valve opening and variable engine speeds. Results demonstrate that the use of alcohol fuels increased the engine torque, brake specific fuel consumption (BSFC), thermal efficiency and combustion efficiency. Furthermore, the cylinder gas pressure and heat release rate occurred earlier; carbon dioxide (CO2) emission increased while hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxides (NOx) emissions decreased.
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Numerical simulation of a reversed flow small-scale combustor

CATEGORY: COMBUSTION
Fuel Processing Technology, Volume 107, March 2013, Pages 126–137
Selected Papers from the Eleventh International Conference on Combustion and Energy Utilization (11th ICCEU)
Numerical simulation of a reversed flow small-scale combustor
M. Graça (a), A. Duarte (a), (b), P.J. Coelho (a), M. Costa (a)
a Mechanical Engineering Department, Instituto Superior Técnico/IDMEC, Technical University of Lisbon, Avenida Rovisco Pais, 1049‐001 Lisbon, Portugal
b Mechanical Engineering Department, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829‐516 Caparica, Portugal
Abstract
A numerical study of a reversed flow small-scale combustor is reported. The combustion chamber is a closed end cylinder with the burner and the exhaust port mounted at the top of the combustor. Natural gas was used as a fuel and the combustion air was preheated to 600 K. Two distinct conditions, achieved by varying the air flow rate were analyzed.
The first was a conventional lean combustion regime. The second corresponded to the flameless combustion regime. The numerical simulations were carried out using ANSYS Fluent 13.0. Turbulence was modeled using the realizable k–ε model. The performance of two different combustion models, namely the eddy dissipation concept (EDC) and the composition PDF (C-PDF) model, was compared. A good agreement between the predictions obtained using the EDC and the C-PDF model was found. However, both models underpredict the measured temperature in the vicinity of the centerline in the region close to the burner. Combustion is delayed in comparison with the experimental data, for both operating conditions.
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Experimental study on the influence of the thermal input on the reaction zone under flameless oxidation conditions

CATEGORY: COMBUSTION
Fuel Processing Technology, Volume 106, February 2013, Pages 423–428
Experimental study on the influence of the thermal input on the reaction zone under flameless oxidation conditions
A.S. Veríssimo, A.M.A. Rocha, M. Costa,
Mechanical Engineering Department, Instituto Superior Técnico, Technical University of Lisbon, Avenida Rovisco Pais, 1049–001 Lisboa, Portugal
Abstract
Researchers investigated the reaction zone of a small-scale laboratory combustor operating under flameless oxidation conditions with the aid of hydroxyl radical chemiluminescence (OH*) imaging and measurements of local mean gas temperatures and local mean major gas species (O₂, CO₂, CO, unburnt hydrocarbons and NO_x) concentrations along the combustor axis, as a function of the fuel (methane) thermal input, which was varied between 7 and 13 kW.
As the fuel thermal input increases, the reaction zone, as typified by the OH* distribution, enlarges. Simultaneously, it moves progressively closer to the combustor exit exhaust due to the increase in the central jet momentum, while maintaining constant the excess air level. The excess air values used by the researchers were low enough to preserve the flameless combustion regime regardless of the fuel thermal input, with the combustor yielding very low NO_x and CO emissions regardless of the fuel thermal input.
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Combustion Regimes of a Jet Diffusion Flame in Hot Co-flow

CATEGORY: COMBUSTION
Energy Fuels, 2013, 27 (6), pp 3488–3498, DOI: 10.1021/ef400500w
Combustion Regimes of a Jet Diffusion Flame in Hot Co-flow
F. Wang †, J. Mi *†‡, and P. Li †
† State Key Laboratory of Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871, China
‡ College of Energy & Power Engineering, Changsha University of Science and Technology, Changsha 410004, China
jcmi@coe.pku.edu.cn
Abstract
Presents a classification of combustion regimes for the diffusion flame of a hydrocarbon fuel jet in hot flue-gas co-flow (JHC) with varying oxygen fraction. Researchers conducted numerical simulations by computational fluid dynamics (CFD) to obtain both forced-ignition and autoignition temperatures.
The Eddy Dissipation Concept (EDC) model with the well-known detailed chemistry-reaction mechanism of methane combustion was used to perform all calculations. Use of the predicted ignition temperatures can qualitatively classify the JHC combustion, based on previous suggestions for combustion in a well-stirred reactor (WSR), into three distinct regimes: traditional combustion (TC), high-temperature combustion (HTC), and flameless combustion (FLC). The FLC regime can be further divided into three distinct zones: MILD (moderate or intense low-oxygen dilution), MILD-like, and quasi-MILD. The MILD and MILD-like combustion regimes share the same necessary conditions proposed by Cavaliere and de Joannon while the quasi-MILD combustion does not.
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Chemical kinetic uncertainty quantification for Large Eddy Simulation of turbulent nonpremixed combustion

CATEGORY: COMBUSTION
Proceedings of the Combustion Institute, Volume 34, Issue 1, 2013, Pages 1299–1306
Chemical kinetic uncertainty quantification for Large Eddy Simulation of turbulent nonpremixed combustion
Michael E. Mueller (a), Gianluca Iaccarino (a), Heinz Pitsch (a), (b)
a Department of Mechanical Engineering, Stanford University, United States
b Institute for Combustion Technology, RWTH Aachen University, Germany
Abstract
Chemical kinetic mechanisms continue to improve in accuracy. However, these mechanisms are still models.  They sometimes embody considerable uncertainty. In order to rigorously validate turbulent combustion simulations against experimental data, this uncertainty must be separated from deficiencies in the turbulent combustion model itself.
Authors present a method for quantifying the uncertainty in turbulent flame simulations due to input uncertainty in the chemical mechanism. The method is designed for Large Eddy Simulation (LES) combined with a steady flamelet model. Rather than a brute force probabilistic approach in which hundreds or thousands of LES runs are required to compute statistics of outputs of interest, the method takes advantage of the actual algorithm employed with the steady flamelet model.
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Combustion time of the oxygenated and non-oxygenated fuels in an Otto cycle engine

CATEGORY: COMBUSTION
J Braz. Soc. Mech. Sci. Eng., DOI 10.1007/s40430-013-0094-y, Published online 27 October 2013
Combustion time of the oxygenated and non-oxygenated fuels in an Otto cycle engine
Pedro Mello • Fabiano Wildner • Giovanni Souza de Andrade • Renato Catalun˜a • Rosaˆngela da Silva
Open Access
Abstract
Speed flame propagation in Otto cycle engines is one of the principal characteristics of fuel and is fundamental in defining the ignition advance. The greater the propagation speed the less the negative work required to compress the mixture before the piston reaches the top dead center and the higher the cycle’s efficiency. This paper presents experimental results of time measurements of the fuel’s ignition and the maximum pressure rating in the combustion chamber of a Cooperative Fuel Research engine specially instrumented.
The combustion duration measurements of oxygenated and non-oxygenated fuels were taken as a function of the compression ratio (8:1, 10:1 and 12:1) and lambda (k). The speed flame propagation in the combustion chamber is significantly changed with the change of the lambda different compression ratios. The VNG has a maximum in the speed flame propagation in the stoichiometric region (k = 1.0) in all compression rates in this study. Similar behavior occurs with ethanol and gasohol, but only in compression ratio 12:1. Ethanol and gasohol have the higher rate of flame propagation for all compression ratios measured as compared to the nonoxygenated (isooctane) and oxygenated fuels (MTBE and TAEE).
Introduction
Due to the constant increase in crude oil-derived liquid fuel prices and the growing restrictions with respect to environmental contamination, interest has focused increasingly on alternative fuels. These fuels can be classified as synthetic gasoline, gasoline with oxygenated compound additives such as methyl tert-butyl ether (MTBE), tert-amyl-ethyl-ether (TAEE). Studies of the speed flame propagation of new oxygenated fuels such as TAEE are important to determine the best ignition advance to reach the maximum brake torque. This paper analyzes the variation in burning speed of a Brazilian commercial gasoline (gasohol), isooctane, MTBE, TAEE, ethanol and vehicular natural gas (VNG) at different compression ratios and air–fuel ratios. Compression ratios used in this study were 8:1, 10:1, and 12:1 for the liquid fuels and 14:1 for VNG. The air–fuel ratios used for each compression ratio were 0.8 and 0.9 (rich mixture), 1.0 (stoichiometric), and 1.1 and 1.2 (lean conditions).
Free Full Text Source: http://download.springer.com/static/pdf/421/art%253A10.1007%252Fs40430-013-0094-y.pdf?auth66=1384636877_f18c9780af4d33bc0f23f0902fffd72b&ext=.pdf 

Simplified Reaction Models for Combustion in Gas Turbine Combustion Chambers

CATEGORY: TURBINES
Flow and Combustion in Advanced Gas Turbine Combustors: Fluid Mechanics and Its Applications, Volume 1581, 2013, pp 161-182
Simplified Reaction Models for Combustion in Gas Turbine Combustion Chambers
Dirk Lebiedz, Jochen Siehr
1. Institute for Numerical Mathematics, University of Ulm, Helmholtzstraße 20, 89081, Ulm, Germany
2. Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Im Neuenheimer Feld 368, 69120, Heidelberg, Germany
Abstract
Despite the growing power of computing technology, the simulation of a reaction-diffusion-convection system involving a large scale chemical combustion mechanism remains out of reach. Yet, prediction of soot, NOx, and other pollutants requires detailed mechanisms.
Authors explain how model reduction methods can be used to generate small models. They first focus on an efficient use of the intrinsic low dimensional manifold method. They then devise a new method based on optimization methods. The result is an efficient tool for solving these optimization problems, making possible the development of reaction models capable of simulating syngas combustion.
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Extended LES-PaSR Model For Simulation Of Turbulent Combustion

CATEGORY: COMBUSTION
Progress in Propulsion Physics 4 (2013) 539-568, DOI: 10.1051/eucass/201304539
Extended LES-PaSR Model For Simulation Of Turbulent Combustion
V. Sabelnikov (1) and C. Fureby (2)
1 ONERA The French Aerospace Lab, Palaiseau 91761, France
2 Defense Security Systems Technology, The Swedish Defense Research Agency FOI, Tumba Stockholm 14725, Sweden
Abstract
In this work, a novel model for Large Eddy Simulations (LES) of high Reynolds moderate Damkohler number turbulent flames is proposed. The development is motivated by the need for more accurate and versatile LES combustion models for engineering applications such as jet engines. The model is based on the finite rate chemistry approach in which the filtered species equations of a reduced reaction mechanism are solved prior to closure modeling. The modeling of the filtered reaction rate provides the challenge: as most of the chemical activity, and thus also most of the exothermicity occurs on the subgrid scales, this model needs to be based on the properties of fine-scale turbulence and mixing and Arrhenius chemistry.
The model developed here makes use of the similarities with the mathematical treatment of multiphase flows together with the knowledge of fine-scale turbulence and chemistry obtained by Direct Numerical Simulation (DNS) and experiments. In the model developed, equations are proposed for the fine-structure composition and volume fraction that are solved together with the LES equations for the resolved scales. If subgrid convection can be neglected, the pro- posed model simplifies to the Partially Stirred Reactor (PaSR) model. To validate the proposed LES model, comparisons with experimental data and other LES results are made, using other turbulence chemistry interaction models, for a lean premixed bluff body stabilized.
Free Full Text Source: http://www.eucass-proceedings.eu/articles/eucass/abs/2013/01/eucass4p539/eucass4p539.html 

Auto-ignition and combustion of diesel spray using unsteady laminar flamelet model

CATEGORY: COMBUSTION
Applied Thermal Engineering, Volume 52, Issue 2, 15 April 2013, Pages 420–427
Auto-ignition and combustion of diesel spray using unsteady laminar flamelet model
Isares Dhuchakallaya (a), Phadungsak Rattanadecho (a), Paul Watkins (b)
a Department of Mechanical Engineering, Thammasat University, Klong-Luang, Pathumthani 12120, Thailand
b School of Mechanical, Aerospace and Civil Engineering, University of Manchester, M13 9PL, UK
Abstract
Describes the modeling capabilities of the unsteady flamelet/reaction progress variable approach to implement diesel spray flames for capturing the auto-ignition and flame lift-off phenomena. The droplet size distribution based on the moment scheme characterizes the poly-disperse spray model employed in this work.
The flamelet progress variable solutions embedded in a Reynolds-averaged Navier–Stokes (RANS) framework, together with the probability density function (PDF) approach, signify the turbulence–chemistry interaction. All thermochemical scalars are represented as a function of mean mixture fraction, mixture fraction variance, reaction progress variable and scalar dissipation rate. Mixture fraction is assumed to follow a beta-PDF distribution, because the reaction progress variable and scalar dissipation rate distributions are assumed to be a delta-PDF. In order to assess the capability of this developed model, the predicted results are compared with experimental data. The model can accurately and efficiently capture the auto-ignition and flame lift-off phenomena of diesel spray flame.
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Reactor choices for chemical looping combustion (CLC) — Dependencies on materials characteristics

CATEGORY: CHEMICAL LOOPING
Energy Procedia, Volume 37, 2013, Pages 567–574
GHGT-11
Reactor choices for chemical looping combustion (CLC) — Dependencies on materials characteristics
Erin Kimball (a), Arnold Lambert (b), Anita Fossdal (c), Rebecca Leenman (a), Elodie Comte (b), W.A.P. van den Bos (a), Richard Blom (c)
a TNO, P.O. Box 6012, NL-2600 JA Delft, The Netherlands
b IFPEN, Rond-point de l’échangeur de Solaize, 69360 Solaize, France
c SINTEF, Pb. 124 Blindern, N-0314 Oslo Norway
Abstract
The physio-chemical stability of the oxygen carrier material during chemical looping combustion (CLC) operation is crucial. In the present paper we discuss the challenges connected to operating a metal oxide base material in a cyclic manner between oxidizing and reducing atmospheres. Especially, focus has been put on the phase changes occurring within the oxygen carrier particles leading to changes in particle volume during operation and consequently, with time, also particle disintegration. Particle sintering may also occur for some oxygen carrier materials in their reduced form. These challenges have been exemplified through lab-scale CLC experiments carried out both in fixed bed and fluidized bed reactors.
Introduction
CLC is a cyclic process where a metal oxide first is used to combust a fuel, and then the reduced metal oxide is re-oxidized in air before a new cycle can be carried out (see Figure 1). Such a red-ox cycle can in principle be carried out in two ways; either i) by moving the metal oxide between static gas streams or ii) by keeping the metal oxide static while switching the gas streams. Option i) is in most cases implemented with a dual circulating fluidized bed (CFB) reactor setup where the metal oxide powder circulates between a fuel reactor, in which the combustion takes place, and an air reactor, where re-oxidation takes place [6][7] CFB reactors have recently gained by far the most attention within the CLC community since this reactor type already has commercial applications for combustion processes (boilers) and within refinery processes, such as fluidized catalytic cracking (FCC). Option ii) most often involves one or more fixed bed reactors where complex valving sequences assure cyclic gas feeding to the reactors and optimal gas separation. Initial CLC experiments were carried out in single fixed bed reactors [3][8].
In the present contribution we will discuss, in more general terms, the properties of the oxygen carrier materials in connection to the kind of reactor used for the CLC process. We will also present data from real CLC experiments conducted in various reactor types using NiO/NiAl2O4 [10] as oxygen carrier (OC) and discuss the material deactivation and particle degradation observed in terms of changes in the particle properties during red-ox cycling at the relevant conditions. The Cu based material Cu0.95Fe1.05AlO4 [9] has been included due to its extreme changes in particle morphology upon red-ox cycling. Also, the changes in particle morphologies upon unplanned stops and failures in the CLC process will be discussed.  
Free Full Text Source: http://www.sciencedirect.com/science/article/pii/S1876610213001537

Studies on a liquid fuel based two stage flameless combustor

CATEGORY: COMBUSTION
Proceedings of the Combustion Institute, Volume 34, Issue 2, 2013, Pages 3319–3326
Studies on a liquid fuel based two stage flameless combustor
V. Mahendra Reddy, Darshan Sawant, Darshan Trivedi, Sudarshan Kumar
Combustion Research Laboratory, Department of Aerospace Engineering, Indian Institute of Technology, Mumbai 400 076, India
Abstract
Reports experimental and numerical results for a two stage combustor capable of achieving flameless combustion mode with 20 kW thermal input and heat release density up to 5 MW/m3.
The fuel and oxidizer are supplied at ambient conditions. Researchers employed the concept of high swirl flows to achieve high internal recirculation rates, residence time and increased dilution of the fresh reactants in the primary combustion zone, resulting in flameless combustion mode. Air is injected through four tangential injection ports located near the bottom of the combustor and liquid fuel is injected through a centrally mounted pressure swirl injector.
According to preliminary computational analysis of the flow features, a decrease in the exit port diameter of the primary chamber increases the recirculation rate of combustion products. This facilitates achieving the flameless combustion mode.
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Numerical Simulation of Air Inlet Conditions Influence on the Establishment of MILD Combustion in Stagnation Point Reverse Flow Combustor

CATEGORY: COMBUSTION
Mathematical Problems in EngineeringVolume 2013 (2013), Article ID 593601, 9 pages, http://dx.doi.org/10.1155/2013/593601
Numerical Simulation of Air Inlet Conditions Influence on the Establishment of MILD Combustion in Stagnation Point Reverse Flow Combustor
Xiao Liu and Hongtao Zheng
College of Power and Energy Engineering, Harbin Engineering University, Harbin, Heilongjiang 150001, China
Introduction
With theworld’s increasing care for purifying and sustainability of environment, moderate or intense low-oxygen dilution combustion (MILD)  is becoming a credible candidate to simultaneously meet themitigation of combustion-generated pollutants (NO𝑥 ) andgreenhouse gases (CO2)whilstmeeting combustion efficiency needs. When the MILD combustion occurs, particularly firing gas and light oil, the entire furnace is bright and transparent and no flame is visible, so that it is often called “flameless combustion (FLOX) ” or “colorless combustion.” This combustion is also named “high temperature air combustion” (HiTAC)  because the combustion air is usually preheated to beyond 1200 K for industrial regenerative combustor systems.
The air preheating requirements of the high temperature air combustion system limits the application of the MILD combustion technology. Because the reversed flow combustion configuration can avoid this procedure, more and more attention was focused here. Yang and Blasiak  showed that flameless oxidation can only be reached if the inlet velocities of the reactants are high enough to establish recirculation zones in the reversed flow combustion chamber. Unfortunately, high velocity of air inlet will lead to combustion instabilities, insufficient residence time, and high CO emission.
These issues may be overcome by a combustor design where both the burner and the exhaust port were mounted at the same end of the combustion chamber.
The present study is aimed at accurately capturing the characteristics of MILD combustion in this reversed flow small-scale combustor, using the modified Eddy Dissipation Concept (EDC) model with detailed mechanism. According to the test conditions of M. Castela , there are two variables from conventional lean combustion to flameless combustion: the total content of oxygen and the momentum (mass and velocity) of the air inlet; therefore, the main objective of the simulations is to investigate and explain the air inlet conditions impact on the establishment of MILD combustion.
Free Full Text Source: http://www.hindawi.com/journals/mpe/2013/593601/abs/ 

Ultra-High Efficiency and Ultra-low Emissions Combustion Technology for Manufacturing Industries.

CATEGORY: ENERGY INTENSITY
Award Number: DE-EE0003478, Project Period: 10:2010 – 12:2012, Date of Report: March 31, 2013
Ultra-High Efficiency and Ultra-low Emissions Combustion Technology for Manufacturing Industries.
Principal Investigator: Arvind Atreya; 734-647-4790; aatreya@umich.edu
Recipient Organization: Regents of the University of Michigan; Research Administration,Ann Arbor, MI
Executive Summary
The purpose of this research was to develop and test a transformational combustion technology for high temperature furnaces to reduce the energy intensity and carbon footprint of U.S. manufacturing industries such as steel, aluminum, glass, metal casting, and petroleum refining.
A new technology based on internal and/or external Flue Gas Recirculation FGR along with significant enhancement in flame radiation was developed. It produces "Radiative Flameless Combustion RFC" and offers tremendous energy efficiency and pollutant reduction benefits over and above the now popular "flameless combustion." It will reduce the energy intensity or fuel consumption per unit system output by more than 50% and double the furnace productivity while significantly reducing pollutants and greenhouse gas emissions 103 times reduction in NOx and 10 times reduction in CO & hydrocarbons and 3 times reduction in CO2. Product quality improvements are also expected due to uniform radiation, as well as, reduction in scale/dross formation is expected because of non‐oxidative atmosphere.
RFC is inexpensive, easy to implement, and it was successfully tested in a laboratory‐scale furnace at the University of Michigan during the course of this work. A first‐ever theory with gas and particulate radiation was also developed. Numerical programs were also written to design an industrial‐scale furnace. Nine papers were published or are in the process of publication. We believe that this early stage research adequately proves the concept through laboratory experiments, modeling and computational models. All this work is presented in the papers. However, due to lack of time, conditions with gas radiation augmented by particulate radiation were not tested. We could also not test the multi‐fuel capability and evaluate the benefits in an industrial furnace with our industrial partners. Important conclusions of this work are: 1 It was proved through experimental measurements that RFC is not only feasible but a very beneficial technology. 2
Theoretical analysis of RFC was done in a spatially uniform strain field and b a planar momentum jet where the strain rate is neither prescribed nor uniform. Four important non‐dimensional parameters controlling RFC in furnaces were identified. These are: I The Boltzmann number; ii The Damkohler number, iii The dimensionless Arrhenius number, and iv The equivalence ratio. Together they define the parameter space where RFC is possible. It was also found that the Damkohler number must be small for RFC to exist and that the Boltzmann number expands the RFC domain. The experimental data obtained during the course of this work agrees well with the predictions made by the theoretical analysis. Interestingly, the equivalence ratio dependence shows that it is easier to establish RFC for rich mixtures than for lean mixtures. This was also experimentally observed. Identifying the parameter space for RFC is necessary for controlling the RFC furnace operation. It is hoped that future work will enable the methodology developed here to be applied to the operation of real furnaces, with consequent improvement in efficiency and pollutant reduction.
The new furnace combustion technology developed enables intense radiation from combustion products and has many benefits:  (i) Ultra‐High Efficiency and Low‐ Emissions;  (ii) Uniform and intense radiation to substantially increase productivity; (iii) Oxygen‐free atmosphere to reduce dross/scale formation; (iv) Provides multi‐fuel capability; and  (v) Enables carbon sequestration if pure oxygen is used for combustion.
Free Full Text Source: http://www.osti.gov/scitech/servlets/purl/1073616

Simulating the impact of premixed charge compression ignition on light-duty diesel fuel economy and emissions of particulates and NOx

CATEGORY: COMBUSTION
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering January 2013 vol. 227 no. 1 31-51
Simulating the impact of premixed charge compression ignition on light-duty diesel fuel economy and emissions of particulates and NOx
Zhiming Gao, C Stuart Daw, Robert M Wagner, K Dean Edwards, David E Smith
gaoz@ornl.gov
Fuels, Engines, and Emissions Research Center, Oak Ridge National Laboratory, Knoxville, TN, USA
Abstract
Presents results from urban drive cycle simulations of a light-duty conventional vehicle and a similar hybrid electric vehicle. Each was equipped with a diesel engine capable of operating in either conventional diesel combustion mode or in premixed charge compression ignition mode.
Both include lean exhaust after-treatment trains for controlling hydrocarbon, carbon monoxide, nitrogen oxide, and particulate matter emissions. Results suggest that, in the simulated conventional vehicle, premixed charge compression ignition can reduce fuel consumption and emissions by a substantial amount by reducing the need for lean nitrogen oxide traps and diesel particulate filter regeneration. Results also indicate that developing ways of extending the premixed charge compression ignition operating range combined with improved control strategies for engine and emissions control management will be especially important for realizing the potential benefits of premixed charge compression ignition in hybrid electric vehicles.
Full Text Source (Subscription or Fee): http://pid.sagepub.com/content/227/1/31.short

Experimental studies on the dual-fuel sequential combustion and emission simulation

CATEGORY: COMBUSTION
Energy, Volume 51, 1 March 2013, Pages 358–373
Experimental studies on the dual-fuel sequential combustion and emission simulation
Xingcai Lu, Xiaoxin Zhou, Libin Ji, Zheng Yang, Dong Han, Chen Huang, Zhen Huang
Key Lab. for Power Machinery and Engineering of M. O. E., Shanghai Jiao Tong University, 200240 Shanghai, PR China
Abstract
Authors demonstrate the simultaneous reductions of NOx and soot using dual-fuel sequential combustion (DFSC), an innovative combustion mode, on a single-cylinder engine.
DFSC introduces a well-mixed, lean fuel/air mixture into the cylinder by injecting high-cetane number fuel  at the intake port, followed by the direct injection of a high-octane number fuel  near the top dead center (TDC). Four fuel combinations were operated with the DFSC mode. Authors examined the ignition mechanism and combustion processes of each fuel combination. Preliminary results reveal that the HC emissions originate primarily from the core region of the spray jet, where the fuel injection tip was unable to fully oxidize and burn. The CO emissions occur primarily at the boundary layer of the cylinder wall, piston ring crevice region, and combustion chamber bowl.
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MILD oxy-combustion of gaseous fuels in a laboratory-scale furnace

CATEGORY: COMBUSTION
Combustion and Flame, Volume 160, Issue 5, May 2013, Pages 933–946
MILD oxy-combustion of gaseous fuels in a laboratory-scale furnace
Pengfei Li (a), Bassam B. Dally (b), Jianchun Mi (a), Feifei Wang (a)
a State Key Laboratory of Turbulence and Complex Systems, Department of Energy & Resources Engineering, College of Engineering, Peking University, Beijing, China
b Center of Energy Technology & School of Mechanical Engineering, The University of Adelaide, Australia
Abstract
Reports a study of the characteristics of Moderate or Intense Low-oxygen Dilution (MILD) oxy-combustion in a laboratory-scale furnace. Researchers conducted experiments using natural gas (NG), liquefied petroleum gas (LPG) and ethylene (C₂H₄) at a firing rate of 13 kW. They recorded the furnace temperatures and exhaust emissions for a range of equivalence ratios and external-CO₂ dilution rates.
They noted that MILD combustions occur for the three fuels even when using pure oxygen as oxidant. When diluting oxidant by CO₂ at a fixed rate, the MILD combustion can be established as long as the equivalence ratio (Φ) is sufficiently high. They observed the region of MILD combustion to be wider with dilution by CO₂ than by N₂. In addition, the operating range of MILD combustion is larger for NG than LPG or C₂H₄ as fuel.
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An advanced combustion model coupled with detailed chemical reaction mechanism for D.I diesel engine simulation

CATEGORY: COMBUSTION
Applied Energy, Volume 111, November 2013, Pages 758–770
An advanced combustion model coupled with detailed chemical reaction mechanism for D.I diesel engine simulation
Amin Maghbouli, Wenming Yang, Hui An, Jing Li, Siaw Kiang Chou, Kian Jon Chua
Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576, Singapore
Abstract
Researchers performed multi-dimensional computational fluid dynamics (CFD) modeling on a direct injection turbo-charged diesel engine based on KIVA-4 code under full and mid engine loads. They used multi-component fuel evaporation model of KIVA-4, coupled with advanced combustion chemistry, to generate a multi-component fuel combustion model by integrating CHEMKIN II into the KIVA-4 code.
The resulting combustion model is able to model the combustion process of several chemical species as the components of direct injected liquid fuel. The model is capable of comprehensive combustion modeling of blend fuel and heavy hydro-carbon fuels. Researchers used it to simulate direct injected diesel engine under full and mid engine loads at three engine speed conditions. Extracted temporal and spatial results for equivalence ratio distribution inside the combustion chamber showed that under full load condition, a considerable amount of fuel was trapped in piston bowl after initiation of the injection process. Such fuel rich local regions provide the potential for production of higher soot emission. Mean value of the fuel concentration history showed that the ignition delay was increased under mid engine load at all engine speeds producing higher amounts of unburned hydro carbons and carbon monoxide.
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Hydrogen addition effects on high intensity distributed combustion

Applied Energy, Volume 104, April 2013, Pages 71–78
Hydrogen addition effects on high intensity distributed combustion
Ahmed E.E. Khalil, Ashwani K. Gupta,
Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA
Abstract
Under the high intensity conditions typical of gas turbines, distributed combustion provides uniform thermal field, ultra-low pollution, enhanced stability and higher efficiency.
Mixing of the fresh air/fuel stream with hot reactive species is critical for distributed reactions and spontaneous ignition. Authors explore hydrogen enrichment of fuel, focusing on combustion stability and emissions under swirling flow conditions. They describe the role of hydrogen enrichment to methane on the combustion characteristics under fuel-lean conditions. CO emission was substantially reduced with hydrogen enrichment, with minimal effect on NO emission under premixed combustion. Hydrogen addition extended the lean operational limits of the combustor with stable combustion and no flame fluctuations or flashback. Results obtained on pollutants emission and flame marking via OH* chemiluminescence revealed near volume distributed high intensity combustion with ultra-low emission  and high performance at lower equivalence ratio.
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Analysis of Combustion and Emission Characteristics of Diesel, Natural Gas Dual Fuel Engine

Advanced Materials Research (Volume 744, 2013), Pages 248-252, DOI 10.4028/www.scientific.net/AMR.744.248
Analysis of Combustion and Emission Characteristics of Diesel, Natural Gas Dual Fuel Engine
Xiao Le Guan, Wei Gang Zheng
Abstract
Reports results of research on combustion characteristics of diesel, natural gas dual fuel engine, as well as analysis of the influence of pilot diesel fuel supply system parameters on the combustion characteristics of dual fuel engine. Researchers compared the combustion characteristics of diesel engine with diesel, natural gas dual fuel engine, and compared the effect of load on the combustion characteristics of dual fuel engines.
Specifically, they explored the load, speed, rate of substitution, effects of ignition oil quantity, inlet concentration of the mixed gas, the fuel supply advance angle and other factors on combustion changes of dual fuel heat release rate, pressure, and discharge characteristics.
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New premixed compression ignition concept for direct injection IC engines fueled with straight-run naphtha

CATEGORY: COMBUSTION
Energy Conversion and Management, Volume 68, April 2013, Pages 161–168
New premixed compression ignition concept for direct injection IC engines fueled with straight-run naphtha
Hongqiang Yang (a), Shijin Shuai (a), Zhi Wang (a), Jianxin Wang (a), Hongming Xu (b)
a State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Haidian District, Beijing 100084, China
b School of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT, UK
Abstract
Reports testing of straight-run naphtha using a novel combustion concept, known as multiple premixed compression ignition (MPCI) mode, on a single cylinder diesel engine at various speeds. For comparative purposes, the partially premixed compression ignition (PPCI) mode is studied, as well.
The MPCI mode was realized by multiple premixed combustion processes in a sequence of spray–combustion–spray–combustion around the compression top dead center (TDC). The spray and combustion events are preferred to be separated completely, with a dominant feature of “Combust After Injection End, Inject After Combustion End” to ensure the multiple-stage premixed compression ignition. The PPCI mode is the well known spray–spray–combustion sequence with the start of combustion (SOC) separated from the end of injection (EOI).
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