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Sample records for hcci combustion mode

  1. Control Strategies for HCCI Mixed-Mode Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Robert M [ORNL; Edwards, Kevin Dean [ORNL

    2010-03-01

    Delphi Automotive Systems and ORNL established this CRADA to expand the operational range of Homogenous Charge Compression Ignition (HCCI) mixed-mode combustion for gasoline en-gines. ORNL has extensive experience in the analysis, interpretation, and control of dynamic engine phenomena, and Delphi has extensive knowledge and experience in powertrain compo-nents and subsystems. The partnership of these knowledge bases was important to address criti-cal barriers associated with the realistic implementation of HCCI and enabling clean, efficient operation for the next generation of transportation engines. The foundation of this CRADA was established through the analysis of spark-assisted HCCI data from a single-cylinder research engine. This data was used to (1) establish a conceptual kinetic model to better understand and predict the development of combustion instabilities, (2) develop a low-order model framework suitable for real-time controls, and (3) provide guidance in the initial definition of engine valve strategies for achieving HCCI operation. The next phase focused on the development of a new combustion metric for real-time characterization of the combustion process. Rapid feedback on the state of the combustion process is critical to high-speed decision making for predictive control. Simultaneous to the modeling/analysis studies, Delphi was focused on the development of engine hardware and the engine management system. This included custom Delphi hardware and control systems allowing for flexible control of the valvetrain sys-tem to enable HCCI operation. The final phase of this CRADA included the demonstration of conventional and spark assisted HCCI on the multi-cylinder engine as well as the characterization of combustion instabilities, which govern the operational boundaries of this mode of combustion. ORNL and Delphi maintained strong collaboration throughout this project. Meetings were held on a bi-weekly basis with additional reports, presentation, and

  2. EXPERIMENTAL INVESTIGATION OF COMBUSTION, PERFORMANCE AND EMISSION CHARACTERISTICS OF DI DIESEL ENGINE UNDER HCCI MODE WITH POROUS MEDIUM COMBUSTION

    Directory of Open Access Journals (Sweden)

    C KANNAN

    2010-08-01

    Full Text Available In recent times, homogeneous combustion has been a proven technology to attain high efficient and low emission engines. Homogenous Charge Compression Ignition (HCCI engines are able to have efficiencies as high as Compression Ignition, Direct Injection (CIDI engines, while producing ultra-low emissions of nitrogen oxides (NOx and particulate matter (PM.HCCI combustion is achieved by controlling the temperature, pressure and composition of the fuel-air mixture so that it spontaneously gets ignited in the combustion chamber. Numeroustechniques such as Variable Exhaust Gas Recirculation (VEGR, ariable Compression Ratio (VCR and Variable Valve Timing (VVT have been proposed to control the homogeneous combustion inside the engine cylinder. Even though these techniques are attractive and having good time response, they are too expensive to afford. This paper investigates the performance, combustion and emission characteristics of a Direct Injection (DI diesel engine under HCCI mode which is established through an effective and affordable technique called Porous Medium Combustion (PMC.

  3. Study the ethanol SI/HCCI combustion mode transition by using the fast thermal management system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper the ethanol homogeneous charge compression ignition (HCCI) is achieved in a modified single cylinder engine by means of a self-developed fast thermal management system (FTMS), and the ethanol SI/HCCI operation regions are defined. It can be concluded that the thermal efficiency is higher and the NOx emission is lower in the HCCI operation region. In addition, the maximum NOx emission drops by 98%. The ethanol SI/HCCI combustion mode transition is conducted in different conditions near the SI/HCCI operation boundaries. It is likely to realize the transition by the utilization of FTMS. However, it is impossible to complete the transition within one operating cycle under current operation conditions. There are fluctuations in engine speed and brake mean effective pressure during the transition process. In order to reduce the fluctuations during the transition, the initial work concerning the effects of the spark ignition on the transition smoothness is carried out and the investigation indicates that the engine speed and brake mean effective pressure fluctuations cannot be eradicated only through spark ignition. Therefore, the control strategies combined with other factors should be further optimized.

  4. Combustion Mode Transition Between HCCI and SI in Load Transition%变工况条件下HCCI/SI燃烧模式转换的实现

    Institute of Scientific and Technical Information of China (English)

    陈韬; 谢辉; 李乐; 虞卫飞; 张松; 赵华

    2012-01-01

    In order to satisfy the request of vehicle engine, SI combustion still needs to be used beyond HCCI operating range. At present, all the methods of HCCI/SI combustion mode transition are realized at the same load, which increases controlling difficulties and brings load fluctuation. To solve the problem of mode transition, a gradual transition from HCCI to SI combustion in load transition was performed by using the variable valve actuation system and external exhaust gas recirculation, and the strategy that the load of engine is controlled by exhaust gas fraction in HCCI combustion was introduced into the SI combustion. The control strategy for all-load is simplified, due to the fact that the complicated control of mode switching has been eliminated.%为了满足车用发动机的要求,在HCCI燃烧的运行范围之外,仍需要使用火花点火(SI)燃烧模式.目前HCCI/SI模式转换的方法和策略都是在相同工况下完成的,这增加了控制上的难度并会带来负荷波动.针对此问题,采用全可变气门机构结合外部废气再循环的方法,在变工况条件下,完成HCCI和SI燃烧模式的转化.并将HCCI燃烧模式中废气率调整负荷的方法延伸进SI燃烧控制中.由于在控制策略层面,采用模式过渡的方法,消除了HCCI/SI模式转换的概念,因而简化了控制策略.

  5. EXPERIMENTAL INVESTIGATION OF COMBUSTION, PERFORMANCE AND EMISSION CHARACTERISTICS OF DI DIESEL ENGINE UNDER HCCI MODE WITH POROUS MEDIUM COMBUSTION

    OpenAIRE

    Kannan, C.; P TAMILPORAI

    2010-01-01

    In recent times, homogeneous combustion has been a proven technology to attain high efficient and low emission engines. Homogenous Charge Compression Ignition (HCCI) engines are able to have efficiencies as high as Compression Ignition, Direct Injection (CIDI) engines, while producing ultra-low emissions of nitrogen oxides (NOx) and particulate matter (PM).HCCI combustion is achieved by controlling the temperature, pressure and composition of the fuel-air mixture so that it spontaneously gets...

  6. Characteristics and energy distribution of modulated multi-pulse injection modes based diesel HCCI combustion and their effects on engine thermal efficiency and emissions

    Institute of Scientific and Technical Information of China (English)

    LIU Bin; SU Wanhua; WANG Hui; HUANG Haozhong

    2007-01-01

    Cycle fuel energy distribution and combustion characteristics of early in-cylinder diesel homogenous charge compression ignition (HCCI) combustion organized by modulated multi-pulse injection modes are studied by the engine test.It is found that heat loss due to unburned fuel droplets and CO emission can be decreased effectively by injection mode regulation,and thermal efficiency can be potentially increased by 4%-12%.From the analyses of combustion process,it is also found that diesel HCCI combustion is a process with a finite reaction rate and is very sensitive to injection timing and injection mode.At injection timing of-90℃A ATDC,extra low NOx emissions can be obtained along with high thermal efficiency.

  7. Analysis of cyclic variability in spark-assisted HCCI combustion using a double Wiebe function

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Robert M [ORNL; Glewen, William J [ORNL; Edwards, Kevin Dean [ORNL; Daw, C Stuart [ORNL

    2008-01-01

    A heuristic algorithm based on a double Wiebe function is proposed for estimating the relative importance of distinct combustion modes (propagating flame and compression ignition) occurring within individual combustion cycles as an engine is transitioned from conventional spark-ignited (SI) combustion to homogeneous charge compression ignition (HCCI). The proposed algorithm automates the analysis and categorization of pressure measurements from large numbers of individual cycles, providing new insight into the unstable combustion processes occurring during mode transition. Similar techniques could potentially be utilized for on-line diagnostics and control of the balance between SI and HCCI combustion in spark-assisted HCCI.

  8. Chemical Kinetic Models for HCCI and Diesel Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Pitz, W J; Westbrook, C K; Mehl, M; Sarathy, S M

    2010-11-15

    Predictive engine simulation models are needed to make rapid progress towards DOE's goals of increasing combustion engine efficiency and reducing pollutant emissions. These engine simulation models require chemical kinetic submodels to allow the prediction of the effect of fuel composition on engine performance and emissions. Chemical kinetic models for conventional and next-generation transportation fuels need to be developed so that engine simulation tools can predict fuel effects. The objectives are to: (1) Develop detailed chemical kinetic models for fuel components used in surrogate fuels for diesel and HCCI engines; (2) Develop surrogate fuel models to represent real fuels and model low temperature combustion strategies in HCCI and diesel engines that lead to low emissions and high efficiency; and (3) Characterize the role of fuel composition on low temperature combustion modes of advanced combustion engines.

  9. Review of homogeneous charge compression ignition (HCCI) combustion engines and exhaust gas recirculation (EGR) effects on HCCI

    Science.gov (United States)

    Akma Tuan Kamaruddin, Tengku Nordayana; Wahid, Mazlan Abdul; Sies, Mohsin Mohd

    2012-06-01

    This paper describes the development in ICE which leads to the new advanced combustion mode named Homogeneous Charge Compression Ignition (HCCI). It explains regarding the theory and working principle of HCCI plus the difference of the process in gasoline and diesel fuelled engines. Many of pioneer and recent research works are discussed to get the current state of art about HCCI. It gives a better indication on the potential of this method in improving the fuel efficiency and emission produced by the vehicles' engine. Apart from the advantages, the challenges and future trend of this technology are also included. HCCI is applying few types of control strategy in producing the optimum performance. This paper looks into Exhaust Gas Recirculation (EGR) as one of the control strategies.

  10. Fuel design real-time to control HCCI combustion

    Institute of Scientific and Technical Information of China (English)

    HOU Yuchun; HUANG Zhen; LU Xingcai; FANG Junhuan; ZU Linlin

    2006-01-01

    In order to achieve lower emissions and extensive load in the homogeneous charge compression ignition (HCCI) engine system, a novel fuel design concept that high-octane number fuel and high-cetane number fuel are mixed real-time to control HCCI combustion is proposed in this study. HCCI combustion fueled with iso-octane/n-heptane mixtures controlled real-time on a single-cylinder HCCI combustion engine is studied. The test results show that the equivalence ratio of n-heptane in mixtures decides ignition and controls the combustion phase of HCCI combustion. The addition of iso-octane extends knocking limit in equivalence ratio somewhat,but knocking occurrence mainly depends on the total concentration of mixture. Although operating range in equivalence ratio becomes narrow with the increasing proportion of iso-octane, the maximum load of HCCI combustion fueled with iso-octane/n-heptane mixtures controlled real-time is increased about 80% more than that of pure n-heptane. When iso-octane/n-heptane mixtures are controlled in optimized method, it is proved that the load of HCCI combustion can be fully extended and emissions can be decreased remarkably, while at the same time the higher indicated thermal efficiencies are obtained over the extensive operation range.

  11. Auto-Ignition of Iso-Stoichiometric Blends of Gasoline-Ethanol-Methanol (GEM) in SI, HCCI and CI Combustion Modes

    KAUST Repository

    Waqas, Muhammad

    2017-03-28

    Gasoline-ethanol-methanol (GEM) blends, with constant stoichiometric air-to-fuel ratio (iso-stoichiometric blending rule) and equivalent to binary gasoline-ethanol blends (E2, E5, E10 and E15 in % vol.), were defined to investigate the effect of methanol and combined mixtures of ethanol and methanol when blended with three FACE (Fuels for Advanced Combustion Engines) Gasolines, I, J and A corresponding to RON 70.2, 73.8 and 83.9, respectively, and their corresponding Primary Reference Fuels (PRFs). A Cooperative Fuel Research (CFR) engine was used under Spark Ignition and Homogeneous Charge Compression Ignited modes. An ignition quality tester was utilized in the Compression Ignition mode. One of the promising properties of GEM blends, which are derived using the iso-stoichiometric blending rule, is that they maintain a constant octane number, which has led to the introduction of methanol as a drop-in fuel to supplement bio-derived ethanol. A constant RON/HCCI fuel number/derived Research octane number property was observed in all three combustion modes for high RON fuels, but for low RON fuels, the iso-stoichiometric blending rule for constant octane number did not appear to be valid. The chemical composition and octane number of the base fuel also influenced the behavior of the GEM blends under different conditions.

  12. Establishment of Combustion Model for Isooctane HCCI Marine Diesel Engine and Research on the Combustion Characteristic

    Directory of Open Access Journals (Sweden)

    Li Biao

    2016-01-01

    Full Text Available The homogeneous charge compression ignition (HCCI combustion mode applied in marine diesel engine is expected to be one of alternative technologies to decrease nitrogen oxide (NOX emission and improve energy utilization rate. Applying the chemical-looping combustion (CLC mechanism inside the cylinder, a numerical study on the HCCI combustion process is performed taking a marine diesel engine as application object. The characteristic feature of combustion process is displayed. On this basis, the formation and emission of NOX are analyzed and discussed. The results indicate that the HCCI combustion mode always exhibit two combustion releasing heats: low-temperature reaction and high-temperature reaction. The combustion phase is divided into low-temperature reaction zone, high-temperature reaction zone and negative temperature coefficient (NTC zone. The operating conditions of the high compression ratio, high intake air temperature, low inlet pressure and small excess air coefficient would cause the high in-cylinder pressure which often leads engine detonation. The low compression ratio, low intake air temperature and big excess air coefficient would cause the low combustor temperature which is conducive to reduce NOX emissions. These technological means and operating conditions are expected to meet the NOX emissions limits in MARPOL73/78 Convention-Annex VI Amendment.

  13. 基于振动信号及瞬时转速信号的HCCI燃烧模式辨识%HCCI Combustion Mode Detection Based on Knock Sensor Signal and Instant Speed

    Institute of Scientific and Technical Information of China (English)

    张宏超; 谢辉; 陈韬; 赵华

    2012-01-01

    HCCI engine adopts combined-mode combustion of pure SI combustion mode, SI-HCCI mode and pure HCCI mode. In such a HCCI combustion control, combustion mode identification becomes very important. Based on a great number of experiments conducted on HCCI engine bench equipped with a fully variable valve actuating system, analysis and comparison are made between knock signal, instant speed and combustion mode. Characteristic parameters are extracted from knock sensor signal and instant speed. Based on the discriminant function analysis, a combustion mode identification model is built with the characteristic parameters, which is simple in computation and easy to be implemented on microcontroller. It is shown that the model is capable of discriminating combustion modes, with the successful detecting rate of around 75%.%HCCI汽油发动机一般采用组合燃烧控制策略,根据发动机工况不同,HCCI汽油机分别采用SI燃烧模式、SI-HCCI燃烧模式和HCCI燃烧模式.在这种控制方式下,燃烧模式的辨识具有非常重要的作用与意义.笔者在装有全可变气门系统的汽油HCCI发动机上,测取HCCI发动机各工况下爆震传感器信号和瞬时转速信号,用时频分析方法从爆震传感器信号和瞬时转速信号中提取了特征量,分析了它们和HCCI汽油机燃烧模式之间的关系.通过辨识函数分析,基于爆震传感器信号特征量和瞬时转速信号特征量,建立了的HCCI燃烧模式辨识模型.分析表明,HCCI燃烧模式辨识模型能够较好地辨识出HCCI的燃烧模式,总体辨识成功率在75%左右.

  14. Optical Study of Flow and Combustion in an HCCI Engine with Negative Valve Overlap

    Science.gov (United States)

    Wilson, Trevor S.; Xu, Hongming; Richardson, Steve; Wyszynski, Miroslaw L.; Megaritis, Thanos

    2006-07-01

    One of the most widely used methods to enable Homogeneous Charge Compression Ignition (HCCI) combustion is using negative valve overlapping to trap a sufficient quantity of hot residual gas. The characteristics of air motion with specially designed valve events having reduced valve lift and durations associated with HCCI engines and their effect on subsequent combustion are not yet fully understood. In addition, the ignition process and combustion development in such engines are very different from those in conventional spark-ignition or diesel compression ignition engines. Very little data has been reported concerning optical diagnostics of the flow and combustion in the engine using negative valve overlapping. This paper presents an experimental investigation into the in-cylinder flow characteristics and combustion development in an optical engine operating in HCCI combustion mode. PIV measurements have been taken under motored engine conditions to provide a quantitative flow characterisation of negative valve overlap in-cylinder flows. The ignition and combustion process was imaged using a high resolution charge coupled device (CCD) camera and the combustion imaging data was supplemented by simultaneously recorded in-cylinder pressure data which assisted the analysis of the images. It is found that the flow characteristics with negative valve overlapping are less stable and more valve event driven than typical spark ignition in-cylinder flows, while the combustion initiation locations are not uniformly distributed.

  15. Reduction of HCCI combustion noise through piston crown design

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper

    2010-01-01

    Seven shapes of piston crowns have been evaluated for their ability to reduce HCCI knock and transmission of combustion noise to the engine. The performance of each piston crown was evaluated with measurements of cylinder pressure, engine vibration and acoustic sound pressure measured one meter a...

  16. Sensitivity of natural gas HCCI combustion to fuel and operating parameters using detailed kinetic modeling

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S; Dibble, R; Flowers, D; Smith, J R; Westbrook, C K

    1999-07-19

    This paper uses the HCT (Hydrodynamics, Chemistry and Transport) chemical kinetics code to analyze natural gas HCCI combustion in an engine. The HCT code has been modified to better represent the conditions existing inside an engine, including a wall heat transfer correlation. Combustion control and low power output per displacement remain as two of the biggest challenges to obtaining satisfactory performance out of an HCCI engine, and these are addressed in this paper. The paper considers the effect of natural gas composition on HCCI combustion, and then explores three control strategies for HCCI engines: DME (dimethyl ether) addition, intake heating and hot EGR addition. The results show that HCCI combustion is sensitive to natural gas composition, and an active control may be required to compensate for possible changes in composition. The three control strategies being considered have a significant effect in changing the combustion parameters for the engine, and should be able to control HCCI combustion.

  17. Control concepts for a gasoline HCCI combustion engine; Strategien zur Regelung von HCCI-Brennverfahren

    Energy Technology Data Exchange (ETDEWEB)

    Karrelmeyer, Roland; Fischer, Wolfgang [Robert Bosch GmbH, Stuttgart (Germany). CR/AEH; Graf, Gerald [Robert Bosch GmbH, Stuttgart (Germany). DGS-EC/ESG; Scherrer, Daniel [Robert Bosch GmbH, Stuttgart (Germany). GS/ECS1; Hathout, Jean-Pierre [Bosch Thermotechnology Sanayi ve Ticaret, A.S. Organize Sanayi Boelgesi, Manisa (Turkey)

    2009-07-01

    In this paper, we discuss an in-cylinder-pressure based controls concept for a HCCI-engine with internal exhaust-gas trapping. Combustion is controlled via the fuel- and air-path. The controls concept is based upon a combination of a feed-forward and a feed-back path. The work has been carried out on gasoline engines with direct-injection and different types of flexible valve trains. In a first step it will be considered a fully flexible type of valve train. On based of cost optimal aspects flexibility will be decreased which resulted in a partly flexible valve train with cam phasers an e. g. two step lift control. A control strategy based on this type of valve train also will be considered. (orig.)

  18. EMISSION AND COMBUSTION CHARACTERISTICS OF DIFFERENT FUELS IN A HCCI ENGINE

    Directory of Open Access Journals (Sweden)

    S. Sendilvelan

    2011-06-01

    Full Text Available Different intake valve timings and fuel injection amounts were tested in order to identify their effects on exhaust emissions and combustion characteristics using variable valve actuation (VVA in a Homogeneous Charge Compression Ignition (HCCI engine. The HCCI engine is a promising concept for future automobile engines and stationary power plants. The two-stage ignition process in a HCCI engine creates advanced ignition and stratified combustion, which makes the ignition timing and combustion rate controllable. Meanwhile, the periphery of the fuel-rich zone leads to fierce burning, which results in slightly high NOx emissions. The experiments were conducted in a modified single cylinder water-cooled diesel engine. In this experiment we use diesel, bio-diesel (Jatropha and gasoline as the fuel at different mixing ratios. HCCI has advantages in high thermal efficiency and low emissions and could possibly become a promising combustion method in internal combustion engines.

  19. Investigation and Optimization of Biodiesel Chemistry for HCCI Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Bunting, Bruce G. [ORNL; Bunce, Michael [ORNL; Joyce, Blake [ORNL; Crawford, Robert W. [Rincon Ranch Consulting

    2014-06-23

    Over the past 5 years, ORNL has run 95 diesel range fuels in homogene-ous charge compression ignition (HCCI), including 40 bio-diesels and associated diesel fuels in their blending. The bio-diesel blends varied in oxygen content, iodine number, cetane, boiling point distribution, chemical composition, and some contained nitrogen. All fuels were run in an HCCI engine at 1800 rpm, in the power range of 2.5 to 4.5 bar IMEP, using intake air heating for combustion phasing control, and at a compression ratio of 10.6. The engine response to fuel variables has been analyzed statistically. Generally, the engine responded well to fuels with lower nitrogen and oxygen, lower cetane, and lower aromatics. Because of the wide range of fuels combined in the model, it provides only a broad overview of the engine response. It is recommended that data be truncated and re-modeled to obtain finer resolution of engine response to particular fuel variables.

  20. Influences of Catalytic Combustion on the Ignition Timing and Emissions of HCCI Engines

    Institute of Scientific and Technical Information of China (English)

    ZENG Wen; XIE Mao-zhao

    2008-01-01

    The combustion processes of homogeneous charge compression ignition (HCCI) engines whose piston surfaces have been coated with catalyst (rhodium or platinum) were numerically investigated. A single-zone model and a multi-zone model were developed. The effects of catalytic combustion on the ignition timing of the HCCI engine were analyzed through the single-zone model. The results showed that the ignition timing of the HCCI engine was advanced by the catalysis. The effects of catalytic combustion on HC, CO and NOx emissions of the HCCI engine were analyzed through the multi-zone model. The results showed that the emissions of HC and CO (using platinum (Pt) as catalyst) were decreased, while the emissions of NOx were elevated by catalytic combustion. Compared with catalyst Pt, the HC emissions were lower with catalyst rhodium(Rh) on the piston surface, but the emissions of NOx and CO were higher.

  1. Operating strategies on HCCI combustion; Betriebsstrategien fuer die Benzinselbstzuendung

    Energy Technology Data Exchange (ETDEWEB)

    Babic, Goran; Bargende, Michael [Stuttgart Univ. (DE). Inst. fuer Verbrennungsmotoren und Kraftfahrzeuge (IVK)

    2010-09-15

    The gasoline self-ignition represents an alternative part load combustion strategy, which radically reduces the nitrogen-oxide emissions in combination with improved process efficiency. At the request of the Research Association for Combustion Engines (FVV) the Institute for Internal Combustion Engines and Automotive Engineering (IVK) of the University of Stuttgart investigated different operating strategies on gasoline self-ignition and developed methods for mode switches under close-to-production conditions. (orig.)

  2. Simulation Analysis of Combustion Parameters and Emission Characteristics of CNG Fueled HCCI Engine

    Directory of Open Access Journals (Sweden)

    P. M. Diaz

    2013-01-01

    Full Text Available The naturally aspirated compressed natural gas (CNG fueled homogeneous charge compression ignition (HCCI engine operation region is narrow between heavy knock at rich air-fuel mixture side and misfire at the lean air-fuel mixture side. However, high activation energy is needed to attain autoignition temperature of CNG fueled HCCI engine. This paper seeks to provide guidance in overcoming challenges of CNG fueled HCCI engine by using CHEMKIN. It is used to investigate the fundamental characteristics of the homogeneous charge compression ignition combustion process for different air-fuel mixture inlet temperature, relative air-fuel ratio of 2.5, and with hemispherical bowl types of combustion chambers. The variation of various properties like the peak cylinder pressure, peak cylinder temperature, CO emission, NO emission, soot emission, and HC emission are studied. It is necessary to develop new combustion models to simulate and predict all parameters with high accuracy.

  3. Reaction Mechanisms and HCCI Combustion Processes of Mixtures of n-Heptane and the Butanols

    Directory of Open Access Journals (Sweden)

    Hu eWang

    2015-03-01

    Full Text Available A reduced primary reference fuel (PRF-Alcohol-Di-tert-butyl Peroxide (DTBP mechanism with 108 species and 435 reactions, including sub-mechanisms of PRF, methanol, ethanol, DTBP and the four butanol isomers, is proposed for homogeneous charge compression ignition (HCCI engine combustion simulations of butanol isomers/n-heptane mixtures. HCCI experiments fuelled with butanol isomer/n-heptane mixtures on two different engines are conducted for the validation of proposed mechanism. The mechanism has been validated against shock tube ignition delays, laminar flame speeds, species profiles in premixed flames and engine HCCI combustion data, and good agreements with experimental results are demonstrated under various validation conditions. It is found that although the reactivity of neat tert-butanol is the lowest, mixtures of tert-butanol/n-heptane exhibit the highest reactivity among the butanol isomer/n-heptane mixtures if the n-heptane blending ratio exceeds 20% (mole. Kinetic analysis shows that the highest C-H bond energy in the tert-butanol molecule is partially responsible for this phenomenon. It is also found that the reaction tC4H9OH+CH3O2 =tC4H9O+CH3O2H plays important role and eventually produces the OH radical to promote the ignition and combustion. The proposed mechanism is able to capture HCCI combustion processes of the butanol/n-heptane mixtures under different operating conditions. In addition, the trend that tert-butanol /n-heptane has the highest reactivity is also captured in HCCI combustion simulations. The results indicate that the current mechanism can be used for HCCI engine predictions of PRF and alcohol fuels.

  4. On the influence of singlet oxygen molecules on characteristics of HCCI combustion: A numerical study

    Science.gov (United States)

    Starik, A. M.; Kozlov, V. E.; Titova, N. S.

    2013-08-01

    Mechanisms of homogeneous charge compression ignition (HCCI) combustion enhancement are investigated numerically when excited O2(a 1Δg) molecules are produced at different points in the compression stroke. The analysis is conducted with the use of an extended kinetic model involving the submechanism of nitric oxide formation in the presence of singlet oxygen O2(a 1Δg) or O2(b 1Σg +) molecules in the methane-air mixture. It is demonstrated that the abundance of excited O2(a 1Δg) molecules in the mixture even in a small amounts intensifies the ignition and combustion and allows one to control the ignition event in the HCCI engine. Such a method of energy supply in the HCCI engine is much more effective in advancement of combustion timing than mere heating of the mixture, because it leads to acceleration of the chain-branching mechanism. The excitation of O2 molecules to the a 1Δg electronic state makes it possible to organise the successful combustion in the cylinder at diminished initial temperature of the mixture and increase the effective energy released during HCCI combustion. The advance in the value of this energy is much higher than the energy needed for the excitation of oxygen molecules. Moreover, in this case, the output concentration of NO and CO can be reduced significantly.

  5. Model and experiments of diesel fuel HCCI combustion with external mixture formation

    Energy Technology Data Exchange (ETDEWEB)

    Canova, M.; Vosz, A.; Dumbauld, D.; Garcin, R.; Midlam-Mohler, S.; Guezennec, Y.; Rizzoni, G. [Ohio State Univ. (United States)

    2005-07-01

    Homogeneous Charge Compression Ignition represents a promising concept for achieving high efficiencies and low emissions at part-load operations. In particular, HCCI combustion can be successfully applied to conventional Direct Injection Diesel engines with very low extra costs and no modification to the DI system by performing the mixture formation in the intake manifold with a novel fuel atomizer. The present paper describes the experimental and modeling activity oriented to the control of HCCI combustion on a conventional CIDI 4-cylinder engine fitted with this external fueling device. Paralleling preliminary results obtained last year on single-cylinder engine in collaboration with FKFS at the University of Stuttgart, Diesel-fuel HCCI combustion was achieved and characterized over a range of engine speeds, loads, EGR dilution and boost pressure. Stable HCCI combustion with negligible NO{sub x} formation (10 ppm) was achieved with no modification of a high compression ratio engine (c{sub r}=18). The in-cylinder pressure traces were analyzed by performing a detailed heat release analysis while accounting for the wall heat transfer, which is substantially higher during the combustion phase than in a conventional CIDI engine. This analysis led to the joint identification of 2 sub-models: a heat transfer model, and a heat release model. It was found that under the wide range of conditions experimentally measured, the heat release can be approximated by the superposition of 3 Wiebe functions. The sub-models developed were then implemented in a combustion model based on a first-law thermodynamic analysis of in-cylinder processes, in order to identify the influence of the main control parameters on HCCI auto-ignition and to control the combustion process in a HCCI Diesel engine with external mixture formation. The model predictions were then compared to the results of a parallel experimental activity made on a 4-cylinder CIDI Diesel engine equipped with the fuel

  6. Digital signal processing of cylinder pressure data for combustion diagnostics of HCCI engine

    Science.gov (United States)

    Kumar Maurya, Rakesh; Pal, Dev Datt; Kumar Agarwal, Avinash

    2013-03-01

    Diagnosis of combustion is necessary for the estimation of the combustion quality, and control of combustion timing in advanced combustion concepts like HCCI. Combustion diagnostics is often performed using digital processing of pressure signals measured using piezoelectric sensor installed in the combustion chamber of the engine. Four-step pressure signal processing consisting of (i) absolute pressure correction, (ii) phasing w.r.t. crank angle, (iii) cycle averaging and (iv) smoothening is used to get cylinder pressure data from the engine experiments, which is further analyzed to get information about combustion characteristics. This study focuses on various aspect of signal processing (cycle averaging and smoothing) of in-cylinder pressure signal from a HCCI engine acquired using a piezoelectric pressure sensor. Experimental investigations are conducted on a HCCI combustion engine operating at different engine speed/load/air-fuel ratio conditions. The cylinder pressure history of 3000 consecutive engine cycles is acquired for analysis using piezoelectric pressure sensor. This study determines the optimum number of engine cycles to be acquired for reasonably good pressure signals based on standard deviation of in-cylinder pressure, rate of pressure rise and rate of heat release signals. Different signal smoothening methods (using various digital filters) are also analyzed and their results are compared. This study also presents effect of signal processing methods on pressure, pressure rise rate and rate of heat release curves at different engine operating conditions.

  7. Controlling the heat release in HCCI combustion of DME with methanol and EGR

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper; Yanai, Tadanori

    2010-01-01

    The effects of methanol and EGR on HCCI combustion of dimethyl ether have been tested separately in a diesel engine. The engine was equipped with a common rail injection system which allowed for random injection of DME. The engine could therefore be operated either as a normal DI CI engine or, by...

  8. Controlling the heat release in HCCI combustion of DME with methanol and EGR

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper; Yanai, Tadanori

    2010-01-01

    The effects of methanol and EGR on HCCI combustion of dimethyl ether have been tested separately in a diesel engine. The engine was equipped with a common rail injection system which allowed for random injection of DME. The engine could therefore be operated either as a normal DI CI engine or, by...

  9. Negative Valve Overlap Mode of HCCI Operation Using Gasoline and Diesel Blended Fuels

    Institute of Scientific and Technical Information of China (English)

    ZHONG Shaohua; CHEN Yongdong; Miroslaw Lech Wyszynski; XU Hongming

    2007-01-01

    The negative valve overlap (NVO) strategy of HCCI operation was experimentally investigated on a gasoline HCCI engine operated with variable valve timing in association with the addition of diesel fuel. The experimental results show that, by using gasoline and diesel blended fuels, the required NVO interval for suitable HCCI combustion under a given engine speed and a moderate compression ratio condition could be reduced, and the HCCI combustion region was extended remarkably without substantial increase in NO, , emissions under a given inlet and exhaust valve timing due to the improvement of charge ignitability. In addition, the possible scale of NVO was extended. A substantial increase in the lean limit of excess air ratio and the upper limit of load range can be achieved because of higher volumetric efficiency, resulting from the decrease in the required NVO and the presence of less residual gases in cylinder.

  10. The Combustion Process Analysis of HCCI Mode of Diesel Engine Fueled with Methanol/Dimethyl Ether%醇醚双燃料均质压缩燃烧过程分析

    Institute of Scientific and Technical Information of China (English)

    闫妍; 张煜盛; 孟忠伟; 吴怡

    2013-01-01

    A multi-dimensional model of methanol / DME dual fuel HCCI engine was established with the consideration of inlet port, exhaust port, and internal asymmetric structure of combustion chamber. The results showed that the multi-dimensional model could predict the cylinder pressure, temperature, the fuel concentration and ignition timing. There were two high temperature regions in HCCI combustion process, the left lower bottom and the right upper edge of the cylinder, the low-temperature reaction firstly started from these regions. The low-temperature reaction started when cylinder average temperature was about 900K , the high-temperature reaction started when cylinder average temperature was about HOOK.%建立了甲醇/二甲醚HCCI发动机燃烧与排放的多维数学模型.模型考虑了进排气道及燃烧室内部不对称结构.利用CFD软件FLUENT耦合双燃料简化动力学模型,对二甲醚/甲醇发动机的HCCI燃烧过程进行了模拟计算.结果表明,多维模型能够较好地预测缸内压力、温度、物质浓度随曲轴转角的变化过程和着火时刻.双燃料HCCI燃烧过程中有2个高温核心,分别是气缸左下底部和右上方边缘地带的两个区域,低温反应最早从这2个部位开始向缸内其他部位延伸.缸内平均温度达到900K左右开始低温反应,1100 K左右开始高温反应.

  11. Quasi-Dimensional Modeling of a CNG Fueled HCCI Engine Combustion Using Detailed Chemical Kinetic

    Directory of Open Access Journals (Sweden)

    Younes Bakhshan

    2013-01-01

    Full Text Available In this study, an in-house quasi dimensional code has been developed which simulates the intake, compression, combustion, expansion and exhaust strokes of a homogeneous charge compression ignition (HCCI engine. The compressed natural gas (CNG has been used as fuel. A detailed chemical kinetic scheme constituting of 310 and 1701 elementary equations developed by Bakhshan et al. has been applied for combustion modeling and heat release calculations. The zero-dimensional k-ε turbulence model has been used for calculation of heat transfer. The output results are the performance and pollutants emission and combustion characteristics in HCCI engines. Parametric studies have been conducted to discussing the effects of various parameters on performance and pollutants emission of these engines.

  12. Fundamental phenomena affecting low temperature combustion and HCCI engines, high load limits and strategies for extending these limits

    KAUST Repository

    Saxena, Samveg

    2013-10-01

    Low temperature combustion (LTC) engines are an emerging engine technology that offers an alternative to spark-ignited and diesel engines. One type of LTC engine, the homogeneous charge compression ignition (HCCI) engine, uses a well-mixed fuel–air charge like spark-ignited engines and relies on compression ignition like diesel engines. Similar to diesel engines, the use of high compression ratios and removal of the throttling valve in HCCI allow for high efficiency operation, thereby allowing lower CO2 emissions per unit of work delivered by the engine. The use of a highly diluted well-mixed fuel–air charge allows for low emissions of nitrogen oxides, soot and particulate matters, and the use of oxidation catalysts can allow low emissions of unburned hydrocarbons and carbon monoxide. As a result, HCCI offers the ability to achieve high efficiencies comparable with diesel while also allowing clean emissions while using relatively inexpensive aftertreatment technologies. HCCI is not, however, without its challenges. Traditionally, two important problems prohibiting market penetration of HCCI are 1) inability to achieve high load, and 2) difficulty in controlling combustion timing. Recent research has significantly mitigated these challenges, and thus HCCI has a promising future for automotive and power generation applications. This article begins by providing a comprehensive review of the physical phenomena governing HCCI operation, with particular emphasis on high load conditions. Emissions characteristics are then discussed, with suggestions on how to inexpensively enable low emissions of all regulated emissions. The operating limits that govern the high load conditions are discussed in detail, and finally a review of recent research which expands the high load limits of HCCI is discussed. Although this article focuses on the fundamental phenomena governing HCCI operation, it is also useful for understanding the fundamental phenomena in reactivity controlled

  13. Numerical study of premixed HCCI engine combustion and its sensitivity to computational mesh and model uncertainties

    Science.gov (United States)

    Kong, Song-Charng; Reitz, Rolf D.

    2003-06-01

    This study used a numerical model to investigate the combustion process in a premixed iso-octane homogeneous charge compression ignition (HCCI) engine. The engine was a supercharged Cummins C engine operated under HCCI conditions. The CHEMKIN code was implemented into an updated KIVA-3V code so that the combustion could be modelled using detailed chemistry in the context of engine CFD simulations. The model was able to accurately simulate the ignition timing and combustion phasing for various engine conditions. The unburned hydrocarbon emissions were also well predicted while the carbon monoxide emissions were under predicted. Model results showed that the majority of unburned hydrocarbon is located in the piston-ring crevice region and the carbon monoxide resides in the vicinity of the cylinder walls. A sensitivity study of the computational grid resolution indicated that the combustion predictions were relatively insensitive to the grid density. However, the piston-ring crevice region needed to be simulated with high resolution to obtain accurate emissions predictions. The model results also indicated that HCCI combustion and emissions are very sensitive to the initial mixture temperature. The computations also show that the carbon monoxide emissions prediction can be significantly improved by modifying a key oxidation reaction rate constant.

  14. Maximizing Power Output in Homogeneous Charge Compression Ignition (HCCI) Engines and Enabling Effective Control of Combustion Timing

    Science.gov (United States)

    Saxena, Samveg

    Homogeneous Charge Compression Ignition (HCCI) engines are one of the most promising engine technologies for the future of energy conversion from clean, efficient combustion. HCCI engines allow high efficiency and lower CO2 emission through the use of high compression ratios and the removal of intake throttle valves (like Diesel), and allow very low levels of urban pollutants like nitric oxide and soot (like Otto). These engines, however, are not without their challenges, such as low power density compared with other engine technologies, and a difficulty in controlling combustion timing. This dissertation first addresses the power output limits. The particular strategies for enabling high power output investigated in this dissertation focus on avoiding five critical limits that either damage an engine, drastically reduce efficiency, or drastically increase emissions: (1) ringing limits, (2) peak in-cylinder pressure limits, (3) misfire limits, (4) low intake temperature limits, and (5) excessive emissions limits. The research shows that the key factors that enable high power output, sufficient for passenger vehicles, while simultaneously avoiding the five limits defined above are the use of: (1) high intake air pressures allowing improved power output, (2) highly delayed combustion timing to avoid ringing limits, and (3) using the highest possible equivalence ratio before encountering ringing limits. These results are revealed by conducting extensive experiments spanning a wide range of operating conditions on a multi-cylinder HCCI engine. Second, this dissertation discusses strategies for effectively sensing combustion characteristics on a HCCI engine. For effective feedback control of HCCI combustion timing, a sensor is required to quantify when combustion occurs. Many laboratory engines use in-cylinder pressure sensors but these sensors are currently prohibitively expensive for wide-scale commercialization. Instead, ion sensors made from inexpensive sparkplugs

  15. Effect of water blending on bioethanol HCCI combustion with forced induction and residual gas trapping

    Energy Technology Data Exchange (ETDEWEB)

    Megaritis, A. [Mechanical Engineering, School of Engineering and Design, Brunel University, West London, Uxbridge UB8 3PH (United Kingdom); Yap, D. [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Wyszynski, M.L. [Mechanical and Manufacturing Engineering, School of Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2007-12-15

    There is increased interest worldwide in renewable engine fuels as well as in new combustion technologies. Bioethanol is one of the alternative fuels that have been used successfully in spark ignition engines. A combustion technology that currently attracts a lot of interest is the homogeneous charge compression ignition (HCCI) combustion, which has shown potential for low nitrogen oxides emissions with no particulate matter formation. The authors have shown previously that applying forced induction to bioethanol HCCI with residual gas trapping results in an extended load range compared to naturally aspirated operation. However, at high boost pressures, high cylinder pressure rise rates develop. Work by other researchers has shown that direct injection of water can be used as a combustion control method. The present work explores water blending as a way that might have an effect on combustion in order to lower the maximum pressure rise rates and further improve emissions. The obtained experimental results show that in contrast to variable rate direct injection of water, fixed rate water-ethanol blending is counterproductive for the reduction of pressure rise rates at higher loads. In addition, increasing the water content in ethanol results in reduction of the effective load range and increased emissions. (author)

  16. Autoignition and Combustion of Natural Gas in a 4 Stroke HCCI Engine

    Science.gov (United States)

    Jun, Daesu; Ishii, Kazuaki; Iida, Norimasa

    Homogeneous charge compression ignition (HCCI) is regarded as the next generation combustion regime in terms of high thermal efficiency and low emissions. It is difficult to control autoignition timing and combustion duration because they are controlled primarily by the chemical kinetics of fuel-air mixture. In this study, it was investigated the characteristics of autoignition and combustion of natural gas in a 4 stroke HCCI engine. And also, to clarify the influence of n-butane on autoignition and combustion of natural gas, it was changed the blend ratio of n-butane from 0mol% to 10mol% in methane/n-butane/air mixtures. Autoignition strongly depends on in-cylinder gas temperature. Autoignition of natural gas occurs when in-cylinder gas temperature reaches in a range of 1000±100K under this experimental condition. To realize high thermal efficiency and low CO emissions, it is necessary to prepare operation conditions that maximum cycle temperature is over 1500K. Autoignition temperature is 25K lower by increasing n-butane blend ratio of 10%. As the blend ratio of n-butane increases, the maximum cycle temperature increases, and THC, CO emissions reduce.

  17. Combustion optimization and HCCI modeling for ultra low emission

    Energy Technology Data Exchange (ETDEWEB)

    Koten, Hasan; Yilmaz, Mustafa; Zafer Gul, M. [Marmara University Mechanical Engineering Department (Turkey)], E-mail: hasan.koten@marmara.edu.tr

    2011-07-01

    With the coming shortage of fossil fuels and the rising concerns over the environment it is important to develop new technologies both to reduce energy consumption and pollution at the same time. In the transportation sector, new combustion processes are under development to provide clean diesel combustion with no particulate or NOx emissions. However, these processes have issues such as limited power output, high levels of unburned hydrocarbons, and carbon monoxide emissions. The aim of this paper is to present a methodology for optimizing combustion performance. The methodology consists of the use of a multi-objective genetic algorithm optimization tool; homogeneous charge compression ignition engine cases were studied with the ECFM-3Z combustion model. Results showed that injected fuel mass led to a decrease in power output, a finding which is in keeping with previous research. This paper presented on optimization tool which can be useful in improving the combustion process.

  18. Interactions Between Surface Reactions and Gas-phase Reactions in Catalytic Combustion and Their Influence on Ignition of HCCI Engine

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The catalytic combustion of methane in a microchannel whose surface was coated with platinum(Pt)catalyst was studied by numerical-simulation. The effects of gas-phase reactions on the whole catalytic combustion process were analyzed at a high inlet pressure. A sensitivity analysis of the detailed mechanisms of the surface reaction of methane on Pt revealed that the most sensitive reactions affecting the heterogeneous ignition are oxygen adsorption/desorption and methane adsorption, and the most sensitive reactions affecting the homogeneous ignition are OH and H2O adsorption/desorption. The combustion process of the homogeneous charge compression ignition(HCCI) engine whose piston face was coated with Pt catalyst was simulated. The effects of catalysis and the most sensitive reactions on the ignition timing and the concentration of the main intermediate species during the HCCI engine combustion are discussed. The results show that the ignition timing of the HCCI engine can be increased by catalysis, and the most sensitive reactions affecting the ignition timing of the HCCI engine are OH and H2O adsorption/desorption.

  19. A numerical study of HCCI combustion of PRF mixtures compared with PCCI experiments

    Energy Technology Data Exchange (ETDEWEB)

    Van Wijngaarden, B.

    2008-09-15

    For automotive applications engines that produce less soot and NOx are desired. For that reason the Homogeneous Charge Compression Ignition (HCCI) principle is investigated all over the world, including the technical universities of Berlin (TUB) and Eindhoven. HCCI combines a homogeneous charge, as in an Otto engine with the autoignition principle of a Diesel engine. Auto-ignition and almost instantaneous combustion of a homogeneous charge leads to almost zero soot emissions, lower temperatures and thereby much lower NOx emissions. Auto-ignition timing however, depends on the fuel and its chemistry, which is very sensitive to the applied conditions, being pressure, temperature, equivalence ratio ({phi}), dilution with EGR and engine speed. To study this systematically a 0D model with PRF fuels is used (Primary Reference Fuels are n-heptane, iso-octane and mixtures). A 0D model is chosen because it excludes complex fluid dynamics and thereby allows the use of detailed combustion mechanisms, describing the (PRF) chemistry. Furthermore the model has a multi zone possibility to evaluate in-homogeneities of the charge. PRF fuels are used because n-heptane (CN=55) auto-ignites like a diesel and iso-octane (ON=100) approaches gasoline. For the PRF chemistry three combustion mechanisms were selected, of which two were validated showing a great difference in predicted ignition delay and sensitivity to changes. Furthermore the model was validated with a PCCI (Premixed Charge Compression Ignition) experiment. Extensive comparisons with PCCI experiments from the TUB showed that when the moment of injection was used to launch the chemistry in the model, only the Soyhan mechanism predicted the ignition close to the experimental ignition moment. Furthermore a 7 zone model was able to approach the experimental CO and NOX emissions. Finally none of the mechanisms was able to predict a pressure profile similar to the experiments. More zones and or a better mechanism could improve

  20. Combustion Mode Design with High Efficiency and Low Emissions Controlled by Mixtures Stratification and Fuel Reactivity

    Directory of Open Access Journals (Sweden)

    Hu eWang

    2015-08-01

    Full Text Available This paper presents a review on the combustion mode design with high efficiency and low emissions controlled by fuel reactivity and mixture stratification that have been conducted in the authors’ group, including the charge reactivity controlled homogeneous charge compression ignition (HCCI combustion, stratification controlled premixed charge compression ignition (PCCI combustion, and dual-fuel combustion concepts controlled by both fuel reactivity and mixture stratification. The review starts with the charge reactivity controlled HCCI combustion, and the works on HCCI fuelled with both high cetane number fuels, such as DME and n-heptane, and high octane number fuels, such as methanol, natural gas, gasoline and mixtures of gasoline/alcohols, are reviewed and discussed. Since single fuel cannot meet the reactivity requirements under different loads to control the combustion process, the studies related to concentration stratification and dual-fuel charge reactivity controlled HCCI combustion are then presented, which have been shown to have the potential to achieve effective combustion control. The efforts of using both mixture and thermal stratifications to achieve the auto-ignition and combustion control are also discussed. Thereafter, both charge reactivity and mixture stratification are then applied to control the combustion process. The potential and capability of thermal-atmosphere controlled compound combustion mode and dual-fuel reactivity controlled compression ignition (RCCI/highly premixed charge combustion (HPCC mode to achieve clean and high efficiency combustion are then presented and discussed. Based on these results and discussions, combustion mode design with high efficiency and low emissions controlled by fuel reactivity and mixtures stratification in the whole operating range is proposed.

  1. Control Strategy Study of Ethanol SI/HCCI Combustion Mode Smooth Transition%乙醇SI/HCCI燃烧模式平稳转换控制策略研究

    Institute of Scientific and Technical Information of China (English)

    黄为钧; 黄焱; 杨晓辉

    2008-01-01

    如何将均质压燃(HCCI)应用到实际发动机上是当前HCCI研究的热点之一,采用HCCI/SI复合燃烧模式是潜力巨大的出路之一.当发动机采用这种复合燃烧模式时,HCCl只能在一定范围内运行的特点决定了发动机在HCCI和SI两种燃烧模式边界工况发生负荷变化时,需要进行两种燃烧模式的相互转换.实现两种燃烧模式的平稳转换需要对转换过程中影响转换平顺性的因素进行分析,综合控制.通过分析试验所得数据,本研究基于主节气门运动规律、点火提前角和供油规律3个主要影响因素提出了主动、协同的控制策略,实现了两种燃烧模式的平稳转换.

  2. Development and Validation of a Reduced DME Mechanism Applicable to Various Combustion Modes in Internal Combustion Engines

    Directory of Open Access Journals (Sweden)

    Gregory T. Chin

    2011-01-01

    Full Text Available A 28-species reduced chemistry mechanism for Dimethyl Ether (DME combustion is developed on the basis of a recent detailed mechanism by Zhao et al. (2008. The construction of reduced chemistry was carried out with automatic algorithms incorporating newly developed strategies. The performance of the reduced mechanism is assessed over a wide range of combustion conditions anticipated to occur in future advanced piston internal combustion engines, such as HCCI, SAHCCI, and PCCI. Overall, the reduced chemistry gives results in good agreement with those from the detailed mechanism for all the combustion modes tested. While the detailed mechanism by Zhao et al. (2008 shows reasonable agreement with the shock tube autoignition delay data, the detailed mechanism requires further improvement in order to better predict HCCI combustion under engine conditions.

  3. Gasoline-like Fuel Effects on High-load, Boosted HCCI Combustion Employing Negative Valve Overlap Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Kalaskar, Vickey B [ORNL; Szybist, James P [ORNL; Splitter, Derek A [ORNL

    2014-01-01

    In recent years a number of studies have demonstrated that boosted operation combined with external EGR is a path forward for expanding the high load limit of homogeneous charge compression ignition (HCCI) operation with the negative valve overlap (NVO) valve strategy. However, the effects of fuel composition with this strategy have not been fully explored. In this study boosted HCCI combustion is investigated in a single-cylinder research engine equipped with direct injection (DI) fueling, cooled external exhaust gas recirculation (EGR), laboratory pressurized intake air, and a fully-variable hydraulic valve actuation (HVA) valve train. Three fuels with significant compositional differences are investigated: regular grade gasoline (RON = 90.2), 30% ethanol-gasoline blend (E30, RON = 100.3), and 24% iso-butanol-gasoline blend (IB24, RON = 96.6). Results include engine loads from 350 to 800 kPa IMEPg for all fuels at three engine speeds 1600, 2000, and 2500 rpm. All operating conditions achieved thermal efficiency (gross indicated efficiency) between 38 and 47%, low NOX emissions ( 0.1 g/kWh), and high combustion efficiency ( 96.5%). Detailed sweeps of intake manifold pressure (atmospheric to 250 kPaa), EGR (0 25% EGR), and injection timing are conducted to identify fuel-specific effects. The major finding of this study is that while significant fuel compositional differences exist, in boosted HCCI operation only minor changes in operational conditions are required to achieve comparable operation for all fuels. In boosted HCCI operation all fuels were able to achieve matched load-speed operation, whereas in conventional SI operation the fuel-specific knock differences resulted in significant differences in the operable load-speed space. Although all fuels were operable in boosted HCCI, the respective air handling requirements are also discussed, including an analysis of the demanded turbocharger efficiency.

  4. Experimental Research on Mode Switch in a Multi-Cylinder HCCI Engine%多缸HCCI汽油机SIAI/AI燃烧模式切换的试验

    Institute of Scientific and Technical Information of China (English)

    李东升; 张志福; 杨万里; 阳冬波; 王志; 王建昕

    2012-01-01

    HCCI/SI composited combustion model is regarded as a practical operation strategy for gasoline HCCI engines.But different demand of air-fuel ratio and internal EGR rate bring the control difficultly in HCCI/SI mode switch.Switch frequency HCCI engine Combustion mode is high due to the narrow load range,and this reduces the operation stability.Based on multi-cylinder gasoline engine with a two-stage CAM profile,the spark-induced auto-ignition(SIAI)was realized,and SIAI/SI combustion mode switch was studied.Results showed that fuel injection at compression stroke combined with spark-ignition strategy can effectively avoid misfire,improve stability of mode switch.SIAI can extend the load operation range of HCCI combustion,and effectively reduce mode switch frequency.%HCCI/SI复合燃烧模式是HCCI汽油发动机实用化的运行策略.但不同的空燃比和内部EGR率的需求给HCCI/SI模式切换带来了极大控制难度;同时由于HCCI负荷范围窄,使得燃烧模式切换频率过高,降低了发动机运行稳定性.在一台具备错位双凸轮机构的多缸汽油机上实现了火花点火激发混合气自燃着火(SIAI)燃烧方式,扩展了压燃模式下的负荷范围,研究了SIAI/SI燃烧模式的切换.结果表明,采用压缩冲程燃油喷射配合火花点火策略能够有效地避免燃烧模式切换中的失火现象,提高模式切换的稳定性;同时采用SIAI燃烧方式扩展内部EGR条件下的负荷范围,可以有效地减小模式切换频率.

  5. A new predictive multi-zone model for HCCI engine combustion

    Energy Technology Data Exchange (ETDEWEB)

    Bissoli, M.; Frassoldati, A.; Cuoci, A.; Ranzi, E.; Mehl, M.; Faravelli, T.

    2016-09-01

    This work introduces a new predictive multi-zone model for the description of combustion in Homogeneous Charge Compression Ignition (HCCI) engines. The model exploits the existing OpenSMOKE++ computational suite to handle detailed kinetic mechanisms, providing reliable predictions of the in-cylinder auto-ignition processes. All the elements with a significant impact on the combustion performances and emissions, like turbulence, heat and mass exchanges, crevices, residual burned gases, thermal and feed stratification are taken into account. Compared to other computational approaches, this model improves the description of mixture stratification phenomena by coupling a wall heat transfer model derived from CFD application with a proper turbulence model. Furthermore, the calibration of this multi-zone model requires only three parameters, which can be derived from a non-reactive CFD simulation: these adaptive variables depend only on the engine geometry and remain fixed across a wide range of operating conditions, allowing the prediction of auto-ignition, pressure traces and pollutants. This computational framework enables the use of detail kinetic mechanisms, as well as Rate of Production Analysis (RoPA) and Sensitivity Analysis (SA) to investigate the complex chemistry involved in the auto-ignition and the pollutants formation processes. In the final sections of the paper, these capabilities are demonstrated through the comparison with experimental data.

  6. Quasi-Dimensional Modelling and Parametric Studies of a Heavy-Duty HCCI Engine

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Pandey

    2011-01-01

    Full Text Available A quasi-dimensional modelling study is conducted for the first time for a heavy duty, diesel-fuelled, multicylinder engine operating in HCCI mode. This quasidimensional approach involves a zero-dimensional single-zone homogeneous charge compression ignition (HCCI combustion model along with a one-dimensional treatment of the intake and exhaust systems. A skeletal chemical kinetic scheme for n-heptane was used in the simulations. Exhaust gas recirculation (EGR and compression ratio (CR were the two parameters that were altered in order to deal with the challenges of combustion phasing control and operating load range extension. Results from the HCCI mode simulations show good potential when compared to conventional diesel performance with respect to important performance parameters such as peak firing pressure, specific fuel consumption, peak pressure rise, and combustion noise. This study shows that HCCI combustion mode can be employed at part load of 25% varying the EGR rates between 0 and 60%.

  7. A Study on the Effects of Compression Ratio, Engine Speed and Equivalence Ratio on HCCI Combustion of DME

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper

    2007-01-01

    An experimental study has been carried out on the homogeneous charge compression ignition (HCCI) combustion of Dimethyl Ether (DME). The study was performed as a parameter variation of engine speed and compression ratio on excess air ratios of approximately 2.5, 3 and 4. The compression ratio...... was adjusted in steps to find suitable regions of operation, and the effect of engine speed was studied at 1000, 2000 and 3000 RPM. It was found that leaner excess air ratios require higher compression ratios to achieve satisfactory combustion. Engine speed also affects operation significantly....

  8. A Study on the Effects of Compression Ratio, Engine Speed and Equivalence Ratio on HCCI Combustion of DME

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper

    2007-01-01

    An experimental study has been carried out on the homogeneous charge compression ignition (HCCI) combustion of Dimethyl Ether (DME). The study was performed as a parameter variation of engine speed and compression ratio on excess air ratios of approximately 2.5, 3 and 4. The compression ratio...... was adjusted in steps to find suitable regions of operation, and the effect of engine speed was studied at 1000, 2000 and 3000 RPM. It was found that leaner excess air ratios require higher compression ratios to achieve satisfactory combustion. Engine speed also affects operation significantly....

  9. Flex Fuel Optimized SI and HCCI Engine

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Guoming; Schock, Harold; Yang, Xiaojian; Huisjen, Andrew; Stuecken, Tom; Moran, Kevin; Zhen, Ron; Zhang, Shupeng

    2013-09-30

    The central objective of the proposed work is to demonstrate an HCCI (homogeneous charge compression ignition) capable SI (spark ignited) engine that is capable of fast and smooth mode transition between SI and HCCI combustion modes. The model-based control technique was used to develop and validate the proposed control strategy for the fast and smooth combustion mode transition based upon the developed control-oriented engine; and an HCCI capable SI engine was designed and constructed using production ready two-step valve-train with electrical variable valve timing actuating system. Finally, smooth combustion mode transition was demonstrated on a metal engine within eight engine cycles. The Chrysler turbocharged 2.0L I4 direct injection engine was selected as the base engine for the project and the engine was modified to fit the two-step valve with electrical variable valve timing actuating system. To develop the model-based control strategy for stable HCCI combustion and smooth combustion mode transition between SI and HCCI combustion, a control-oriented real-time engine model was developed and implemented into the MSU HIL (hardware-in-the-loop) simulation environment. The developed model was used to study the engine actuating system requirement for the smooth and fast combustion mode transition and to develop the proposed mode transition control strategy. Finally, a single cylinder optical engine was designed and fabricated for studying the HCCI combustion characteristics. Optical engine combustion tests were conducted in both SI and HCCI combustion modes and the test results were used to calibrate the developed control-oriented engine model. Intensive GT-Power simulations were conducted to determine the optimal valve lift (high and low) and the cam phasing range. Delphi was selected to be the supplier for the two-step valve-train and Denso to be the electrical variable valve timing system supplier. A test bench was constructed to develop control strategies for

  10. Studies of the Combustion Process with Simultaneous Formaldehyde and OH PLIF in a Direct-Injected HCCI Engine

    Science.gov (United States)

    Richter, Mattias; Collin, Robert; Nygren, Jenny; Aldén, Marcus; Hildingsson, Leif; Johansson, Bengt

    This paper presents simultaneous laser based measurements of formaldehyde and OH-radical distributions in a 0.5 liter optical HCCI engine with direct injection. Formaldehyde is formed as an intermediate species when combusting hydrocarbons. The formation occurs through low temperature reactions in an early phase of the combustion process. Later in the process formaldehyde is being consumed. Formaldehyde is, therefore, used as indicator of the first stage of combustion and a marker of zones with low-temperature reactions. The OH radical is formed as an intermediate during the high temperature reactions, and is used as a marker of zones where the combustion is ongoing. The purpose of the investigation was to study how the combustion process is affected by the change in homogeneity that arises from early and late injection, respectively. The measurement technique used was planar laser-induced fluorescence where formaldehyde was excited at 355nm and OH at 283nm.

  11. Application of micro-genetic algorithm for calibration of kinetic parameters in HCCI engine combustion model

    Institute of Scientific and Technical Information of China (English)

    Haozhong HUANG; Wanhua SU

    2008-01-01

    The micro-genetic algorithm (μGA) as a highly effective optimization method, is applied to calibrate to a newly developed reduced chemical kinetic model (40 species and 62 reactions) for the homogeneous charge compression ignition (HCCI) combustion of n-heptane to improve its autoignition predictions for different engine operating conditions. The seven kinetic parameters of the calibrated model are determined using a combination of the Micro-Genetic Algorithm and the SENKIN program of CHEMKIN chemical kinetics software package. Simulation results show that the autoignition predictions of the calibrated model agree better with those of the detailed chemical kinetic model (544 species and 2 446 reactions) than the original model over the range of equivalence ratios from 0.1-1.3 and temperature from 300-3 000 K. The results of this study have demonstrated that the μGA is an effective tool to facilitate the calibration of a large number of kinetic parameters in a reduced kinetic model.

  12. The Effects of Charge Stratification on the Limit Load and Combustion Characteristics of HCCI Gasoline Engine%混合气分层对HCCI汽油机极限负荷和燃烧特性的影响

    Institute of Scientific and Technical Information of China (English)

    张建珍; 刘军

    2011-01-01

    对比研究HCCI汽油机在不同空燃比下采用混合气分层策略时的极限负荷、NOx排放量和燃油经济性,考察了在此策略下过量空气系数λ和EGR率对HCCI发动机燃烧特性的影响.结果表明,混合气分层压缩燃烧模式能有效降低HCCI燃烧的压力升高率,具有拓展负荷范围的潜力,但同时也使NOx排放增加;适当的过量空气系数能在一定程度上改善HCCI发动机的燃烧特性,采用9%的EGR率时发动机油耗率最低,具有明显节油效果.%The limit loads, N0x emission and fuel economy of HCCI gasoline engine with a mixture forming strategy of charge stratification under different air-fuel ratio are comparatively studied. With this strategy the effects of EGR rate and excess air coefficient on the combustion characteristics of HCCI engine are investigated. The results indicate that stratified charge compression ignition can reduce the rising rate of combustion pressure and has the potential for extending load range of HCCI mode, but it leads to a higher N0x emission; the appropriate excess air coefficient can improve the combustion characteristics of HCCI engine and the specific fuel consumption reaches its lowest point at a EGR rate of 9% , showing tangible results of fuel saving.

  13. Method and device for diagnosing and controlling combustion instabilities in internal combustion engines operating in or transitioning to homogeneous charge combustion ignition mode

    Science.gov (United States)

    Wagner, Robert M [Knoxville, TN; Daw, Charles S [Knoxville, TN; Green, Johney B [Knoxville, TN; Edwards, Kevin D [Knoxville, TN

    2008-10-07

    This invention is a method of achieving stable, optimal mixtures of HCCI and SI in practical gasoline internal combustion engines comprising the steps of: characterizing the combustion process based on combustion process measurements, determining the ratio of conventional and HCCI combustion, determining the trajectory (sequence) of states for consecutive combustion processes, and determining subsequent combustion process modifications using said information to steer the engine combustion toward desired behavior.

  14. Modeling and Simulation of a Free-Piston Engine with Electrical Generator Using HCCI Combustion

    Science.gov (United States)

    Alrbai, Mohammad

    governing equations represent a single zone perfectly stirred reactor (PSR) which contain a perfect mixing ideal gas mixture. The chemical kinetics approach is applied using Cantera/ MATLABRTM toolbox, which presents the combustion process. In this research, a homogenous charge compression ignition (HCCI) at different operational conditions is used. HCCI engines have high efficiencies and low emissions and can work within a wide range of fuels. The results have been presented in a multi-cycle simulation and a parametric study forms. In the case of the multi-cycle simulation, a 100 cycles of the engine operation have been simulated. The overall work that is delivered to the electrical generator presents 47% of the total fuel energy. The model indicates an average frequency of 125 Hz along the operational cycles. In order to eliminate the cyclic variations and ensure a continuous operation, a proportional derivative (PD) controller has been employed. The controller adjusts the generator load in order to minimize the difference between the bottom dead center (BDC) locations along the operation cycles. The PD controller shows weakness in achieving the full steady state operation, for this purpose; a proportional integral (PI) controller has been implemented. The PI controller seeks to achieve a specific compression ratio. The results show that; the PI controller indicates unique behavior after 15 cycles of operation where the model ended to fluctuate between two compression ratios only. The complex relation between the thermodynamics and the dynamics of the engine is the greatest challenge in examining the effectiveness of the PI controller. In the parametric investigations, EGR examinations show that NOx emission is reduced to less than the half, as 30 % of EGR is used; this occurs due to the EGR thermal and dilution effects, which cause significant drop in the peak bulk temperature and CO emissions as well. Under the applied conditions, EGR has the ability to raise the work

  15. Numerical Investigation Into Effect of Fuel Injection Timing on CAI/HCCI Combustion in a Four-Stroke GDI Engine

    Science.gov (United States)

    Cao, Li; Zhao, Hua; Jiang, Xi; Kalian, Navin

    2006-02-01

    The Controlled Auto-Ignition (CAI) combustion, also known as Homogeneous Charge Compression Ignition (HCCI), was achieved by trapping residuals with early exhaust valve closure in conjunction with direct injection. Multi-cycle 3D engine simulations have been carried out for parametric study on four different injection timings in order to better understand the effects of injection timings on in-cylinder mixing and CAI combustion. The full engine cycle simulation including complete gas exchange and combustion processes was carried out over several cycles in order to obtain the stable cycle for analysis. The combustion models used in the present study are the Shell auto-ignition model and the characteristic-time combustion model, which were modified to take the high level of EGR into consideration. A liquid sheet breakup spray model was used for the droplet breakup processes. The analyses show that the injection timing plays an important role in affecting the in-cylinder air/fuel mixing and mixture temperature, which in turn affects the CAI combustion and engine performance.

  16. Flex Fuel Optimized SI and HCCI Engine

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Guoming; Schock, Harold; Yang, Xiaojian; Huisjen, Andrew; Stuecken, Tom; Moran, Kevin; Zhen, Ron; Zhang, Shupeng

    2013-09-30

    The central objective of the proposed work is to demonstrate an HCCI (homogeneous charge compression ignition) capable SI (spark ignited) engine that is capable of fast and smooth mode transition between SI and HCCI combustion modes. The model-based control technique was used to develop and validate the proposed control strategy for the fast and smooth combustion mode transition based upon the developed control-oriented engine; and an HCCI capable SI engine was designed and constructed using production ready two-step valve-train with electrical variable valve timing actuating system. Finally, smooth combustion mode transition was demonstrated on a metal engine within eight engine cycles. The Chrysler turbocharged 2.0L I4 direct injection engine was selected as the base engine for the project and the engine was modified to fit the two-step valve with electrical variable valve timing actuating system. To develop the model-based control strategy for stable HCCI combustion and smooth combustion mode transition between SI and HCCI combustion, a control-oriented real-time engine model was developed and implemented into the MSU HIL (hardware-in-the-loop) simulation environment. The developed model was used to study the engine actuating system requirement for the smooth and fast combustion mode transition and to develop the proposed mode transition control strategy. Finally, a single cylinder optical engine was designed and fabricated for studying the HCCI combustion characteristics. Optical engine combustion tests were conducted in both SI and HCCI combustion modes and the test results were used to calibrate the developed control-oriented engine model. Intensive GT-Power simulations were conducted to determine the optimal valve lift (high and low) and the cam phasing range. Delphi was selected to be the supplier for the two-step valve-train and Denso to be the electrical variable valve timing system supplier. A test bench was constructed to develop control strategies for

  17. Investigations of the causes of hydrocarbon emissions in spark ignition engines with homogeneous charge compression ignition (HCCI). A report of the Institute for Internal Combustion Engines and Automotive Engineering, TU Vienna (IVK); Untersuchung der Ursachen fuer Kohlenwasserstoff-Emissionen beim Ottomotor mit homogener Selbstzuendung (HCCI). Bericht des Instituts fuer Verbrennungskraftmaschinen und Kraftfahrzeugbau derTechnischen Universitaet Wien (IVK)

    Energy Technology Data Exchange (ETDEWEB)

    Geringer, B. (ed.) [Technische Univ., Vienna (Austria); Loch, A.

    2007-07-01

    The main aim of research and development in the field of internal combustion engine is to create an engine with low fuel consumption and hence low carbon dioxide emissions to meet future emissions regulations as well as providing a good driving experience. Homogeneous charge compression ignition (HCCI) is an alternative combustion process being currently developed that promises a good fuel consumption rate and low nitrogen oxide emissions for the gasoline engine. The only legally restricted exhaust gas emissions for this combustion process are carbon monoxide (CO) and hydrocarbons (HC). The aim of this research was a better understanding of the causes and sources of hydrocarbon emissions with HCCI using gasoline so as to further reduce hydrocarbon emissions. A description of the HCCI combustion process is followed by a list of the known sources of hydrocarbon emission in conventional gasoline engines and current knowledge of the causes of hydrocarbon emission with HCCI. It is assumed that many of the known causes of hydrocarbon emissions in the conventional gasoline combustion process are the same for HCCI. For this reason, this study focused on combustion and carburation, which is where the combustion processes differ the most. (orig.)

  18. A Simple HCCI Engine Model for Control

    Energy Technology Data Exchange (ETDEWEB)

    Killingsworth, N; Aceves, S; Flowers, D; Krstic, M

    2006-06-29

    The homogeneous charge compression ignition (HCCI) engine is an attractive technology because of its high efficiency and low emissions. However, HCCI lacks a direct combustion trigger making control of combustion timing challenging, especially during transients. To aid in HCCI engine control we present a simple model of the HCCI combustion process valid over a range of intake pressures, intake temperatures, equivalence ratios, and engine speeds. The model provides an estimate of the combustion timing on a cycle-by-cycle basis. An ignition threshold, which is a function of the in-cylinder motored temperature and pressure is used to predict start of combustion. This model allows the synthesis of nonlinear control laws, which can be utilized for control of an HCCI engine during transients.

  19. Application of a Genetic Algorithm to the Optimization of Rate Constants in Chemical Kinetic Models for Combustion Simulation of HCCI Engines

    Science.gov (United States)

    Kim, Sang-Kyu; Ito, Kazuma; Yoshihara, Daisuke; Wakisaka, Tomoyuki

    For numerically predicting the combustion processes in homogeneous charge compression ignition (HCCI) engines, practical chemical kinetic models have been explored. A genetic algorithm (GA) has been applied to the optimization of the rate constants in detailed chemical kinetic models, and a detailed kinetic model (592 reactions) for gasoline reference fuels with arbitrary octane number between 60 and 100 has been obtained from the detailed reaction schemes for iso-octane and n-heptane proposed by Golovitchev. The ignition timing in a gasoline HCCI engine has been predicted reasonably well by zero-dimensional simulation using the CHEMKIN code with this detailed kinetic model. An original reduced reaction scheme (45 reactions) for dimethyl ether (DME) has been derived from Curran’s detailed scheme, and the combustion process in a DME HCCI engine has been predicted reasonably well in a practical computation time by three-dimensional simulation using the authors’ GTT code, which has been linked to the CHEMKIN subroutines with the proposed reaction scheme and also has adopted a modified eddy dissipation combustion model.

  20. Path planning during combustion mode switch

    Science.gov (United States)

    Jiang, Li; Ravi, Nikhil

    2015-12-29

    Systems and methods are provided for transitioning between a first combustion mode and a second combustion mode in an internal combustion engine. A current operating point of the engine is identified and a target operating point for the internal combustion engine in the second combustion mode is also determined. A predefined optimized transition operating point is selected from memory. While operating in the first combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion engine to approach the selected optimized transition operating point. When the engine is operating at the selected optimized transition operating point, the combustion mode is switched from the first combustion mode to the second combustion mode. While operating in the second combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion to approach the target operating point.

  1. Direct numerical simulations of ignition of a lean n-heptane/air mixture with temperature and composition inhomogeneities relevant to HCCI and SCCI combustion

    KAUST Repository

    Luong, Minh Bau

    2015-12-01

    The effects of temperature and composition stratifications on the ignition of a lean n-heptane/air mixture at three initial mean temperatures under elevated pressure are investigated using direct numerical simulations (DNSs) with a 58-species reduced mechanism. Two-dimensional DNSs are performed by varying several key parameters: initial mean temperature, T0, and the variance of temperature and equivalence ratio (T\\' and φ\\') with different T-φcorrelations. It is found that for cases with φ\\' only, the overall combustion occurs more quickly and the mean heat release rate (HRR) increases more slowly with increasing φ\\' regardless of T0. For cases with T\\' only, however, the overall combustion is retarded/advanced in time with increasing T\\' for low/high T0 relative to the negative-temperature coefficient (NTC) regime resulting from a longer/shorter overall ignition delay of the mixture. For cases with uncorrelated T-φfields, the mean HRR is more distributed over time compared to the corresponding cases with T\\' or φ\\' only. For negatively-correlated cases, however, the temporal evolution of the overall combustion exhibits quite non-monotonic behavior with increasing T\\' and φ\\' depending on T0. All of these characteristics are found to be primarily related to the 0-D ignition delays of initial mixtures, the relative timescales between 0-D ignition delay and turbulence, and the dominance of the deflagration mode during the ignition. These results suggest that an appropriate combination of T\\' and φ\\' together with a well-prepared T-φdistribution can alleviate an excessive pressure-rise rate (PRR) and control ignition-timing in homogeneous charge compression-ignition (HCCI) combustion. In addition, critical species and reactions for the ignition of n-heptane/air mixture through the whole ignition process are estimated by comparing the temporal evolution of the mean mass fractions of important species with the overall reaction pathways of n

  2. An Investigation of the Effect of Charge Inhomogeneity on the Ignition and Combustion Processes in a HCCI Engine Using Chemiluminescence Imaging

    Science.gov (United States)

    Kumano, Kengo; Yamasaki, Yudai; Iida, Norimasa

    In the HCCI (Homogeneous Charge Compression Ignition) engines, inhomogeneity in fuel distribution and temperature in the pre-mixture exists microscopically and has possibility to affect the ignition and combustion process. In this study, the effect of charge inhomogeneity in fuel distribution on the HCCI combustion process was investigated. Pressure profiles were measured and two dimensional chemiluminescence images were captured by using a framing camera with a 4-stroke optically accessible engine in order to understand the spatial distribution of the combustion. DME (di-methyl ether) was used as the test fuel. By changing the way of mixing air and fuel in the intake manifold, inhomogeneity in fuel distribution in the pre-mixture was varied. The result shows that luminescence is observed in a very short time in a large part of the combustion chamber under the homogeneous condition, while luminescence appears locally with considerable time differences under the inhomogeneous condition. It is also shown that the local luminescence durations are almost the same under both conditions.

  3. Investigation of combustion, performance and emission characteristics of 2-stroke and 4-stroke spark ignition and CAI/HCCI operations in a DI gasoline

    OpenAIRE

    Y. Zhang; Zhao, H.

    2014-01-01

    In order to develop more efficient and cleaner gasoline engines, a number of new engine operating strategies have been proposed and researched on different engines, including the spark ignition (SI) and controlled autoignition (CAI) or HCCI in both 2-stroke and 4-stroke cycles in a poppet valve engine. In this work, a single cylinder direct injection gasoline engine equipped with an electro-hydraulic valve-train system has been commissioned and used to achieve seven different operating modes,...

  4. The Research of Homogeneous Charge Compression Ignition (HCCI) Combustion%均质压燃式(HCCI)燃烧的研究

    Institute of Scientific and Technical Information of China (English)

    王大兴; 张欣; 刘建华

    2002-01-01

    均质压燃式(HCCI)燃烧方式是目前内燃机燃烧领域的研究热点.HCCI燃烧是以预混合燃烧和低温反应为特征的燃烧方式.采用HCCI燃烧方式可以同时有效降低柴油机的NOx和碳烟排放,并提高柴油机的循环热效率.HCCI发动机通常工作在高空燃比和较低的压缩比条件下,工作范围较小,高负荷时功率输出不足."双模式"HCCI发动机是解决上述问题的有效途径,并成为近期HCCI发动机研究中的热点.

  5. Research of Controlling of Homogeneous Charge Compression Ignition (HCCI) Combustion Procedure%均质压燃(HCCI)燃烧过程控制方式的研究

    Institute of Scientific and Technical Information of China (English)

    卢美秀; 张欣; 李从心

    2004-01-01

    均质压燃(HCCI)燃烧方式是目前内燃机燃烧领域的研究焦点.因HCCI发动机的燃烧过程主要由可燃混合气的化学动力学所控制,故很难在全负荷范围内控制它的着火时刻和燃烧放热率.因此,HCCI燃烧过程的控制成为HCCI研究热点.本文根据一些控制HCCI发动机燃烧过程的研究结果对其进行阐述.

  6. 二甲醚均质混合压燃燃烧数值模拟研究%Combustion Numerical Simulation of DME HCCI

    Institute of Scientific and Technical Information of China (English)

    邓航; 邓惜仁; 吴先焕

    2016-01-01

    In this paper, the simulation study on dimethyl ether HCCI combustion is carried out by using the large-scale chemical reaction kinetics software CHEMKIN, combined with the detailed chemical kinetics model of DME. The combustion chemical kinetics mechanism of DME is investigated in theory. And the influences of boundary conditions on DME HCCI combustion are analyzed. The results show that the maximum pressure and the maximum temperature in the cylinder are increased with the increase of the intake air temperature, excess air coefficient and the increase of initial pressure.%文章利用大型化学反应动力学软件CHEMKIN结合二甲醚详细化学反应动力模型,对二甲醚的HCCI燃烧进行了模拟研究,从理论上研究探讨二甲醚的HCCI燃烧机理,构建了二甲醚HCCI反应动力学的简化模型,并研究了边界条件对二甲醚HCCI燃烧的影响。结果表明:随着进气温度的升高、过量空气系数的减小、初始压力的增加,缸内的最高压力升高,最大燃烧温度上升。

  7. Performance and emission study on DICI and HCCI engine using raw pongamia oil and diesel

    Directory of Open Access Journals (Sweden)

    Mani Venkatraman

    2016-01-01

    Full Text Available The present work investigates the performance and emission characteristics of pongamia oil and diesel fuelled direct injection compression ignition (DICI and homogeneous charge compression ignition (HCCI engine. The primary objective of the work is to investigate the feasibility of application of unmodified pongamia oil in Diesel engine and to estimate the maximum fraction of diesel fuel replaced by the neat pongamia oil. This investigation also deals with the HCCI operation using unmodified pongamia oil. In DICI mode the neat pongamia oil is admitted into the engine in the form of pongamia oil and diesel blends. The blend that offers highest diesel replacement is considered as the test blend and it is tested further to find its maximum possible brake thermal efficiency by changing the engine operating parameters. The selected maximum blend is then tested in the new setting of the engine to determine the maximum possible performance and emission characteristics. The conventional emissions of DICI engine such as NO and smoke are disappeared in the homogeneous charge compression ignition mode of operation. The HCCI engine tested in the present work is fuelled by 40% neat pongamia oil and 60% diesel fuel through direct injection and vapour induction, respectively. The ignition or combustion phasing of the HCCI operation is carried out by the exhaust gas recirculation method. The amount of exhaust gas re-circulation governs the timing of combustion. The results of the experiments show that the neat pongamia oil performed well in HCCI mode and offered approximately ten times lower NO and smoke emission. Finally, the results of the DICI mode and HCCI mode are compared with each other to reveal the truths of neat pongamia oil in heterogeneous and homogeneous combustion.

  8. 废气再循环和进气加热实现汽油机HCCI燃烧的性能对比%Performance Comparison of Gasoline Engine HCCI Combustion Approached by EGR and Intake Heating

    Institute of Scientific and Technical Information of China (English)

    虞卫飞; 谢辉; 李乐; 陈韬; 赵华

    2012-01-01

    废气再循环和进气加热是实现汽油机HCCI燃烧的两种不同方式,其对HCCI燃烧性能的影响也不同,为此,在同一台汽油机上分别采用废气再循环和进气加热实现HCCI燃烧,并分析了其在HCCI燃烧性能上存在差异的机理.试验结果表明,相对于进气加热,废气再循环的工质比热容高,但由于稀释比较小,使得其工质总热容反而低,从而缸内燃烧温度高.废气再循环HCCI燃烧的未燃HC排放比进气加热的排放值低41% ~ 59%;NOx排放是后者的2 ~ 20倍;而CO排放与负荷有关;其燃烧效率比迸气加热HCCI的值高0.8%~14%.然而,由于进气加热的PMEP低,缸内工质比热比大,传热损失小,最终使得进气加热HCCI燃烧的ISFC比废气再循环HCCI燃烧的值低6.6%~16.4%.%Exhaust gas recirculation(EGR)and intake heating are two different approaches for gasoline engine to achieving homogeneous charge compression ignition (HCCI) combustion and have different performances on HCCI combustion. Therefore, experiments were carried out on a single-cylinder gasoline engine with HCCI combustion using EGR and intake heating, respectively, to study the different performance mechanisms of the two approaches on HCCI combustion. The experimental results show that, compared with the HCCI combustion with intake heating, the specific heat of charge with EGR is higher. However, lower dilution ratio leads to lower total specific heat of charge , which results in higher in-cylinder combustion temperature. The unburned hydrocarbons (UHC)emission generated by HCCI combustion with EGR is 41%?9% lower than that by HCCI combustion using intake heating. NO, emission of the former is 2?0 times that of the latter, and the CO emission depends on the IMEP. The combustion efficiency of HCCI combustion with EGR is 0.8%?4% higher than that of HCCI combustion with intake heating. However, due to lower pumping mean effective pressure, higher specific heat ratio of

  9. Research on the Influence of Hydrogen and Carbon Monoxide on Methane HCCI Combustion

    Science.gov (United States)

    Sato, Susumu; Yamasaki, Yudai; Kawamura, Hideo; Iida, Norimasa

    In this research, the influence on natural gas combustion of H2 and CO was investigated by numerical calculations with elementary reactions. The investigation was carried out using the following procedures: 1. To research basic oxidation characteristics of CH4/H2/CO mixed fuel, parametric calculations for initial temperature were carried out. 2. For investigation of the effect of H2 and CO on CH4 combustion, the calculations with H2 and CO initial mole fraction variation was carried out. As a result, it was clarified that the oxidation temperature of CO was higher than that of CH4 and H2, the increase of H2 initial fraction has the effect to advance CH4 ignition timing, and increase of the CO fraction, under the condition that only CO was added, has the opposite effect of H2 addition.

  10. Experimental Study on Dimethyl Ether Combustion Process in Homogeneous Charge Compression Ignition Mode

    Institute of Scientific and Technical Information of China (English)

    郑尊清; 史春涛; 尧命发

    2004-01-01

    Experimental study on homogeneous charge compression ignition (HCCI) combustion process was carried out on a single-cylinder direct injection diesel engine fueled with dimethyl ether(DME). The influence of inert gas CO2 on the ignition and combustion process was investigated. The research results indicate that because of the high cetane number of DME, the stable HCCI operating range is quite narrow while the engine has a high compression ratio. The HCCI operating range can be largely extended when the inert gas is inducted into the charging air. HCCI combustion of DME presents remarkable characteristic of two-stage combustion process. As the concentration of inert gas increases, the ignition timing of the first combustion stage delays, the peak heat release rate decreases, and the combustion duration extends. Inducting inert gas into charging air cannot make the combustion and heat release of DME occur at a perfect crank angle position. Therefore,to obtain HCCI operation for the fuel with high cetane number,other methods such as reducing engine compression ratio should be adopted. Emission results show that under HCCI operation, a nearly zero NOx emission can be obtained with no smoke emissions. But the HC and CO emissions are high, and both rise with the increase of the concentration of inert gases.

  11. 汽油HCCI发动机HCCI/SI模式过渡控制的研究%Research on HCCI/SI Mode Transition Control of Gasoline HCCI Engine

    Institute of Scientific and Technical Information of China (English)

    周能辉; 谢辉; 张岩; 陈韬; 赵华

    2007-01-01

    由于HCCI燃烧不能覆盖发动机全部工况,因此一台实用的发动机必须具有HCCI/SI模式过渡的功能.针对目前开发的进排气门升程和相位均独立连续调整的汽油HCCI发动机模式过渡的需要,开发了基于CAN总线分布式的HCCI汽油机控制系统,在此基础上对HCCI/SI模式过渡控制进行详细地研究,本文详细地介绍了其结构及其控制策略.由于该控制系统采用自适应PID策略控制进排气门升程和相位,神经网络预测模式过渡中的发动机进气量.实验结果表明:该控制系统解决了HCCI模式过渡中的进排气门升程、相位和空燃比的控制问题,通过细化气门参数能较好地管理混合放热率型线,满足HCCI/SI模式动态平滑过渡的控制需求.

  12. Effect of EGR on combustion and emission of methanol HCCI engine%EGR对甲醇HCCI发动机燃烧与排放的影响

    Institute of Scientific and Technical Information of China (English)

    赵伟; 张春化; 佟娟娟; 吴晗

    2012-01-01

    针对均质压燃燃烧难以控制的问题,在一台发动机上,改装进排气系统,并加装均质混合气供油系统和进气加热系统,研究了外部EGR(废气再循环)对甲醇HCCI(均质充量压缩着火)燃烧与排放特性的影响。结果表明:外部EGR对甲醇HCCI燃烧过程和排放都有显著的影响,随EGR率的增加,CA10、CA50逐渐推迟,燃烧持续期逐渐延长,但影响的程度因混合气浓度的不同而变化;HC和CO排放逐渐增加,且增加的幅度逐渐变大;NOx排放仅在混合气较浓时存在(过量空气系数小于1.5时),且随着EGR率的增加迅速下降。%In order to deal with the problem that the combustion of homogeneous charge compression ignition (HCCI) is difficult to control, the impacts of external exhaust gas recirculation (EGR) on methanol HCCI combustion and emission characteristics were investigated on a modi- fied engine by modifying intake and exhaust system, adding HCCI fuel supply system and intake- heating system. The results show that the EGR has a remarkable influence on the combustion and emission of methanol HCCI. As the EGR ratio increases, CA10 and CAS0 gradually delay and the combustion duration prolongs, the change level varies with the differences of mixture concentration, the emissions of unburned hydrocarbon and monoxide carbon quickly increase. Ni- trogen oxide can only be detected at the condition of relative richer mixture (air-fuel equivalence ratio less than 1.5), and its quantity decreases quickly with the EGR ratio going up. 1 tab, 8 figs, 9 refs.

  13. Nonlinear Model Predictive Control of A Gasoline HCCI Engine Using Extreme Learning Machines

    OpenAIRE

    Janakiraman, Vijay Manikandan; Nguyen, XuanLong; Assanis, Dennis

    2015-01-01

    Homogeneous charge compression ignition (HCCI) is a futuristic combustion technology that operates with a high fuel efficiency and reduced emissions. HCCI combustion is characterized by complex nonlinear dynamics which necessitates a model based control approach for automotive application. HCCI engine control is a nonlinear, multi-input multi-output problem with state and actuator constraints which makes controller design a challenging task. Typical HCCI controllers make use of a first princi...

  14. Experimental Study on OKP HCCI Gasoline Engine%优化动力HCCI汽油机的试验研究

    Institute of Scientific and Technical Information of China (English)

    缪金荣; 张旭洲; 沈义涛; 陈林; 方俊华; 吕兴才; 黄震

    2011-01-01

    With the OKP technology, the HCCI combustion of 4-cylinder gasoline engine was realized through intake heating.The performance of combustion, HC emission and fuel consumption for OKP HCCI gasoline engine was researched, the influences of compression ratio and excess air ratio on HCCI combustion were analyzed and the HC emission rule during the SI-HCCI switching was researched by the experiment. The results indicate that OKP HCCI gasoline engine can realize the SI-HCCI switch in 15 cycles. Through the HCCI combustion, the fuel consumption rate decreases dramatically and the HC emission level is equivalent to or even lower than that of SI mode.%采用优化动力(OKP)技术手段,利用进气加热实现了产品4缸汽油机的HCCI燃烧.研究了OKP HCCI汽油机的燃烧、HC排放及燃油消耗等特性,分析了压缩比及过量空气系数对HCCI燃烧的影响,并对SI-HCCI切换过程中HC排放规律进行了试验研究.结果表明,OKP HCCI汽油机能在15个循环内实现SI-HCCI燃烧模式的切换,HCCI燃烧能大幅地降低燃油消耗并且能达到与SI模式相当甚至更低水平的HC排放.

  15. Influence of Operating Parameters on Methanol HCCI Combustion Stability and Cycle-to-cycle Variation%运行参数对甲醇 HCCI 燃烧稳定性和循环变动的影响

    Institute of Scientific and Technical Information of China (English)

    潘江如; 张春化; 鲁亚云

    2014-01-01

    为研究进气温度、过量空气系数和发动机转速对甲醇HCCI燃烧循环变动和燃烧稳定性的影响,在1台改造的试验发动机上进行相关的试验。试验结果表明:随着进气温度的升高,循环变动变大,最高燃烧压力的分布较为集中;循环变动系数对过量空气系数较为敏感,随着过量空气系数的增大,循环变动变大,最高燃烧压力的分布较为分散;随着转速的增大,循环变动变小,最高燃烧压力的平均值变大,最高燃烧压力分布集中,对于甲醇而言,进气温度为160℃,过量空气系数为2时,n=1300 r/min是较优的转速。%In order to study the influences of intake temperature ,excess air coefficient and engine speed on methanol HCCI combustion stability and cycle-to-cycle variation ,the relevant tests were carried out on a retrofit engine .The results show that the cycle-to-cycle variation increases and the distribution of maximum combustion pressure concentrates with the increase of in-take temperature .The excess air coefficient is more sensitive to the coefficient of cycle-to-cycle variation .With the increase of excess air coefficient , the cycle-to-cycle variation decreases and the distribution of maximum combustion pressure scatters . With the increase of engine speed ,the cycle-to-cycle variation decreases ,the mean value of maximum combustion pressure in-creases and its distribution concentrates .For the methanol fuel ,1 300 r/min is the optimal speed at 160 ℃ of intake tempera-ture and when the excess air coefficient is 2 .

  16. Application Performance Investigation of HCCI Combustion Technique%HCCI燃烧技术应用性能研究

    Institute of Scientific and Technical Information of China (English)

    任勇; 陈浩; 潘磊

    2014-01-01

    均质压燃(HCCI)是一种全新的燃烧方式,它能够有效地提高发动机的燃烧热效率,降低NOx和碳烟的排放.阐述了HCCI燃烧的特点、HCCI燃烧技术的优点、需要解决的技术问题,介绍了将HCCI燃烧技术应用到汽油机、柴油机上的一些方法,最后对HCCI燃烧技术的应用前景进行了展望.

  17. The modes of gaseous combustion

    CERN Document Server

    Rubtsov, Nickolai M

    2016-01-01

    This book provides an analysis of contemporary problems in combustion science, namely flame propagation, detonation and heterophaseous combustion based on the works of the author. The current problems in the area of gas combustion, as well as the methods allowing to calculate and estimate limiting conditions of ignition, and flame propagation on the basis of experimental results are considered. The book focuses on the virtually inaccessible works of Russian authors and will be useful for experienced students and qualified scientists in the area of experimental studies of combustion processes.

  18. An extended multi-zone combustion model for PCI simulation

    Science.gov (United States)

    Kodavasal, Janardhan; Keum, SeungHwan; Babajimopoulos, Aristotelis

    2011-12-01

    Novel combustion modes are becoming an important area of research with emission regulations more stringent than ever before, and with fuel economy being assigned greater importance every day. Homogeneous Charge Compression Ignition (HCCI) and Premixed Compression Ignition (PCI) modes in particular promise better fuel economy and lower emissions in internal combustion engines. Multi-zone combustion models have been popular in modelling HCCI combustion. In this work, an improved multi-zone model is suggested for PCI combustion modelling. A new zoning scheme is suggested based on incorporating the internal energy of formation into an earlier conventional HCCI multi-zone approach, which considers a two-dimensional reaction space defined by equivalence ratio and temperature. It is shown that the added dimension improves zoning by creating more representative zones, and thus reducing errors compared to the conventional zoning approach, when applied to PCI simulation.

  19. Direct numerical simulations of exhaust gas recirculation effect on multistage autoignition in the negative temperature combustion regime for stratified HCCI flow conditions by using H2O2 addition

    Science.gov (United States)

    El-Asrag, Hossam A.; Ju, Yiguang

    2013-04-01

    Direct numerical simulations (DNSs) of a stratified flow in a homogeneous compression charge ignition (HCCI) engine are performed to investigate the exhaust gas recirculation (EGR) and temperature/mixture stratification effects on the autoignition of synthetic dimethyl ether (DME) in the negative temperature combustion region. Detailed chemistry for a DME/air mixture is employed and solved by a hybrid multi-time scale (HMTS) algorithm to reduce the computational cost. The effect of ? to mimic the EGR effect on autoignition are studied. The results show that adding ? enhances autoignition by rapid OH radical pool formation (34-46% reduction in ignition delay time) and changes the ignition heat release rates at different ignition stages. Sensitivity analysis is performed and the important reactions pathways affecting the autoignition are specified. The DNS results show that the scales introduced by thermal and mixture stratifications have a strong effect after the low temperature chemistry (LTC) ignition especially at the locations of high scalar dissipation rates. Compared to homogenous ignition, stratified ignitions show similar first autoignition delay times, but 18% reduction in the second and third ignition delay times. The results also show that molecular transport plays an important role in stratified low temperature ignition, and that the scalar mixing time scale is strongly affected by local ignition in the stratified flow. Two ignition-kernel propagation modes are observed: a wave-like, low-speed, deflagrative mode and a spontaneous, high-speed, ignition mode. Three criteria are introduced to distinguish these modes by different characteristic time scales and Damkhöler numbers using a progress variable conditioned by an ignition kernel indicator. The low scalar dissipation rate flame front is characterized by high displacement speeds and high mixing Damkhöler number. The proposed criteria are applied successfully at the different ignition stages and

  20. A parametric study on the emissions from an HCCI alternative combustion engine resulting from the auto-ignition of primary reference fuels

    Energy Technology Data Exchange (ETDEWEB)

    Machrafi, Hatim; Cavadias, Simeon; Amouroux, Jacques [UPMC Universite Paris 06, LGPPTS, Ecole Nationale Superieure de Chimie de Paris, 11, rue de Pierre et Marie Curie, 75005 Paris (France)

    2008-08-15

    The homogeneous charge compression ignition is an alternative combustion technology that can reduce automobile pollution, provided that the exhaust emission can be controlled. A parametric study can be useful in order to gain more understanding in the emission reduction possibilities via this new combustion technology. For this purpose, the inlet temperature, the equivalence ratio and the compression ratio are changed, respectively, from 30 to 70{sup o}C, 0.28 to 0.41 and 6 to 14. Also the diluting, thermal and chemical effects of exhaust gas recirculation were studied. The emission of CO, CO{sub 2}, O{sub 2} and hydrocarbons has been measured using primary reference fuels. It appears that an increase in the inlet temperature, the EGR temperature, the equivalence ratio and the compression ratio results into a decrease of the emissions of CO and the hydrocarbons of up to 75%. The emission of CO{sub 2} increased, however, by 50%. The chemical parameters showed more complicated effects, resulting into a decrease or increase of the emissions, depending on whether the overall reactivity increased or not. If the reactivity increased, generally, the emissions of CO and hydrocarbons increased, while that of CO{sub 2} increased. The increase of CO{sub 2} emissions could be compensated by altering the compression ratio and the EGR parameters, making it possible to control the emission of the HCCI engine. (author)

  1. 甲醇燃料对实现HCCI燃烧小负荷工况的实验研究%Experimental Research on the Realization of HCCI Low-load Combustion with Methanol

    Institute of Scientific and Technical Information of China (English)

    叶坦

    2015-01-01

    近年来国内外对内燃机燃料的研究日趋深入,含氧燃料成为重要的研究课题。甲醇燃料相对于乙醇和汽油燃料表现出了较好的自燃性能,并且甲醇有较高的耐废气能力,这些对HCCI小负荷燃烧的燃油经济性非常有利。通过实验对比甲醇和汽油燃料在废气管理过程中的出现的问题,研究甲醇对小负荷HCCI燃烧拓展的影响。研究发现甲醇燃料对HCCI小负荷着火燃烧有很大的好处,而且甲醇燃料的使用燃烧效率得到提高以后,可以大幅降低HC和CO的排放,但是对于HCCI燃烧运行的负荷边界而言,更容易引起发动机粗暴燃烧。%With researches on the fuel of internal combustion engine are getting further home and abroad in recent years,oxygenated fuel has become an important research object.Compared with ethanol and gasoline,methanol shows the better spontaneous combustion per-formance and higher exhausts tolerance ability which is favorable to the fuel of economic HCCI combustion at low load condition. Through experimental comparisons of problems in exhausts treatment between methanol and gasoline,the effects of methanol on HCCI low-load combustion development have been studied.Research shows that methanol fuels do much promotion to HCCI low-load com-bustion ignition and reduce the emission of HC and CO greatly with the improvement of methanol fuel combustion efficiency while it’s more likely to cause rough combustion of the engine on the operating load boundary of HCCI combustion.

  2. HCCI Engine Optimization and Control

    Energy Technology Data Exchange (ETDEWEB)

    Rolf D. Reitz

    2005-09-30

    The goal of this project was to develop methods to optimize and control Homogeneous-Charge Compression Ignition (HCCI) engines, with emphasis on diesel-fueled engines. HCCI offers the potential of nearly eliminating IC engine NOx and particulate emissions at reduced cost over Compression Ignition Direct Injection engines (CIDI) by controlling pollutant emissions in-cylinder. The project was initiated in January, 2002, and the present report is the final report for work conducted on the project through December 31, 2004. Periodic progress has also been reported at bi-annual working group meetings held at USCAR, Detroit, MI, and at the Sandia National Laboratories. Copies of these presentation materials are available on CD-ROM, as distributed by the Sandia National Labs. In addition, progress has been documented in DOE Advanced Combustion Engine R&D Annual Progress Reports for FY 2002, 2003 and 2004. These reports are included as the Appendices in this Final report.

  3. Numerical simulation and validation of SI-CAI hybrid combustion in a CAI/HCCI gasoline engine

    Science.gov (United States)

    Wang, Xinyan; Xie, Hui; Xie, Liyan; Zhang, Lianfang; Li, Le; Chen, Tao; Zhao, Hua

    2013-02-01

    SI-CAI hybrid combustion, also known as spark-assisted compression ignition (SACI), is a promising concept to extend the operating range of CAI (Controlled Auto-Ignition) and achieve the smooth transition between spark ignition (SI) and CAI in the gasoline engine. In this study, a SI-CAI hybrid combustion model (HCM) has been constructed on the basis of the 3-Zones Extended Coherent Flame Model (ECFM3Z). An ignition model is included to initiate the ECFM3Z calculation and induce the flame propagation. In order to precisely depict the subsequent auto-ignition process of the unburned fuel and air mixture independently after the initiation of flame propagation, the tabulated chemistry concept is adopted to describe the auto-ignition chemistry. The methodology for extracting tabulated parameters from the chemical kinetics calculations is developed so that both cool flame reactions and main auto-ignition combustion can be well captured under a wider range of thermodynamic conditions. The SI-CAI hybrid combustion model (HCM) is then applied in the three-dimensional computational fluid dynamics (3-D CFD) engine simulation. The simulation results are compared with the experimental data obtained from a single cylinder VVA engine. The detailed analysis of the simulations demonstrates that the SI-CAI hybrid combustion process is characterised with the early flame propagation and subsequent multi-site auto-ignition around the main flame front, which is consistent with the optical results reported by other researchers. Besides, the systematic study of the in-cylinder condition reveals the influence mechanism of the early flame propagation on the subsequent auto-ignition.

  4. Performance of HCCI Diesel Engine under the Influence of Various Working and Geometrical Parameters

    OpenAIRE

    Karthikeya Sharma, T.; G. Amba Prasada Rao; K.Madhu Murthy

    2012-01-01

    Homogenous-charge-compression-ignition (HCCI) engines have the benefit of high efficiency with low emissions of NO and particulates. These benefits are due to the autoignition process of the dilute mixture of fuel and air during compression. Homogenous Compression ignition (HCCI) is a combustion concept, which is a hybrid between Otto engine and Diesel engine. The other emissions like HC and CO are high but can be after treated by a catalyst. This paper reviews the Characteristics of HCCI com...

  5. 均质压燃排放实验研究%An experimentalstudy of HCCI emission

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    A big challenge for engine design and reform at home and abroad is the more stringent emission regulations. Homogeneous Charge Compression Ignition (HCCI), as a new combustion mode, has provid-ed direction for the engines with low emission and broad vision for the design of internal combustion engine. Based on the HCCI experiment in a traditional diesel, the two-phase heat release for n-heptane is verified and the influences of the HCCI emissions on intake temperature and excess air coefficient are studied in the paper.%  更为严格的排放法规,是对国内外发动机设计与改造的巨大挑战。均质压燃(HCCI)作为一种新型燃烧模式,为低排放发动机提供了发展方向,也为内燃机设计提供了广阔视野。本文通过传统柴油机上的HCCI实验,验证了正庚烷的两阶段放热,并研究了进气温度和过量空气系数对HCCI排放的影响。

  6. Control of homogeneous charge compression ignition combustion in a two-cylinder gasoline direct injection engine with negative valve overlap

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi; WANG Jianxin; SHUAI Shijin; MA Qingjun; TIAN Guohong

    2007-01-01

    Homogeneous charge compression ignition(HCCI) has challenges in ignition timing control,combustion rate control,and operating range extension.In this paper,HCCI combustion was studied in a two-cylinder gasoline direct injection (GDI) engine with negative valve overlap (NVO).A two-stage gasoline direct injection strategy combined with negative valve overlap was used to control mixture formation and combustion.The gasoline engine could be operated in HCCI combustion mode at a speed range of 800-2 200 r/min and load,indicated mean effective pressure (IMEP) range of 0.1-0.53 MPa.The engine fuel consumption 4× 10-5 without soot emission.The effect of different injection strategies on HCCI combustion was studied.The experimental results indicated that the coefficient of variation of the engine cycle decreased by using NVO with two-stage direct injection;the ignition timing and combustion rate could be controlled;and the operational range of HCCI combustion could be extended.

  7. Numerical investigations on HCCI engine with increased induction induced swirl and engine speed

    Institute of Scientific and Technical Information of China (English)

    T. Karthikeya Sharma; G. Amba Prasad Rao; K. Madhu Murthy

    2015-01-01

    Homogeneous charge compression ignition (HCCI) mode of combustion is popularly known for achieving simultaneous reduction of NOx as well as soot emissions as it combines the compression ignition (CI) and spark ignition (SI) engine features. In this work, a CI engine was simulated to work in HCCI mode and was analyzed to study the effect of induction induced swirl under varying speeds using three-zone extended coherent flame combustion model (ECFM-3Z, compression ignition) of STAR-CD. The analysis was done considering speed ranging from 800 to 1600 r/min and swirl ratios from 1 to 4. The present study reveals that ECFM-3Z model has well predicted the performance and emissions of CI engine in HCCI mode. The simulation predicts reduced in-cylinder pressures, temperatures, wall heat transfer losses, and piston work with increase in swirl ratio irrespective of engine speed. Also, simultaneous reduction in CO2 and NOx emissions is realized with higher engine speeds and swirl ratios. Low speeds and swirl ratios are favorable for low CO2 emissions. It is observed that increase in engine speed causes a marginal reduction in in-cylinder pressures and temperatures. Also, higher turbulent energy and velocity magnitude levels are obtained with increase in swirl ratio, indicating efficient combustion necessitating no modifications in combustion chamber design. The investigations reveal a total decrease of 38.68% in CO2 emissions and 12.93% in NOx emissions when the engine speed increases from 800 to 1600 r/min at swirl ratio of 4. Also an increase of 14.16% in net work done is obtained with engine speed increasing from 800 to 1600 r/min at swirl ratio of 1. The simulation indicates that there is a tradeoff observed between the emissions and piston work. It is finally concluded that the HCCI combustion can be regarded as low temperature combustion as there is significant decrease in in-cylinder temperatures and pressures at higher speeds and higher swirl ratios.

  8. Performance of HCCI Diesel Engine under the Influence of Various Working and Geometrical Parameters

    Directory of Open Access Journals (Sweden)

    T. Karthikeya Sharma

    2012-06-01

    Full Text Available Homogenous-charge-compression-ignition (HCCI engines have the benefit of high efficiency with low emissions of NO and particulates. These benefits are due to the autoignition process of the dilute mixture of fuel and air during compression. Homogenous Compression ignition (HCCI is a combustion concept, which is a hybrid between Otto engine and Diesel engine. The other emissions like HC and CO are high but can be after treated by a catalyst. This paper reviews the Characteristics of HCCI combustion in direct injection diesel engines under various governing factors in HCCI operations such as injection timing, injection pressure, piston bowl geometry, compression ratio, intake charge temperature, exhaust gas recirculation (EGR and supercharging or turbo charging are discussed in this review. The effects of design and operating parameters on HCCI diesel combustion, emissions particularly NOx and soot are reviewed.

  9. 异辛烷、乙醇及其混合燃料HCCI燃烧的试验研究和分析%Experimental Study and Analysis on HCCI Combustion of Iso-Octane, Ethanol and Their Blend

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    在一台改制的发动机上进行了异辛烷、乙醇及其混合燃料HCCI燃烧的研究.发动机性能用缸内压力评估,研究用的参数包括放热率、平均指示压力和热效率.试验结果表明,乙醇着火时刻早于异辛烷;在乙醇中加入异辛烷可以推迟着火,并导致平均指示压力和热效率的降低;对某种特定燃料,HCCI燃烧的发生主要取决于进气充量温度,初始充量温度的增加将导致HCCI燃烧提前;充量温度低或发动机转速低时,混合气形成质量差,对HCCI燃烧有不良影响;指示热效率为30%~43%,其值高于火花点火发动机;预燃室的存在有利于稳定的HCCI燃烧;超稀充量运行可以显著降低NOx排放.%This paper investigates homogeneous charge compression ignition (HCCI) combustion on a modified engine fuelled with iso-octane, ethanol and iso-octane-ethanol blend. The engine performances are evaluated based on in-cylinder measured pressure. The parameters studied include heat-release rate (HRR), indicated mean effective pressure (IMEP) and indicated thermal efficiency. The experimental results demonstrate that the combustion for ethanol occurs ahead of that for iso-octane. The addition of iso-octane to ethanol retards the on-set of combustion and subsequently leads to a reduction of the IMEP and indicated thermal efficiency. For a particular fuel, the combustion depends mainly on the intake charge temperature and any increase in the initial charge temperature leads to advance in combustion. At lower charge temperatures and engine speeds, the fuel-air mixtures' quality of is poor, resulting in a poor combustion. The indicated thermal efficiency is 30% to 43%, better than those of typical SI engines. The presence of pre-chamber is advantageous to stable HCCI operation. Operation with ultra-lean mixture reduces engine-out NOx emissions significantly.

  10. Imaging Studies of the Effects of Ethanol/Gasoline Blends on Spark-Assisted HCCI

    Science.gov (United States)

    Fatouraie, Mohammad; Wooldridge, Margaret

    2012-10-01

    Spark assist (SA) has been demonstrated to extend the operating limits of homogeneous charge compression ignition (HCCI) modes of engine operation. This experimental investigation focuses on the effects caused by the SA HCCI operation on ignition and combustion properties of 100% indolene and 70% indolene/30% ethanol blends. The spark assist effects are compared to base line HCCI for each blend by varying spark timing at different fuel/air equivalence ratio (φ= 0.4--0.6). High speed imaging is used to understand the effects of flame propagation on heat release rates. Ethanol generally improves engine performance with higher indicated mean effective pressure (IMEP) and higher stability compared to 100% indolene. SA advances phasing within a range of 5 CAD at lower engine speeds (700 rpm) and 11 CAD at higher engine speeds (1200 rpm). SA does not affect heat release rates until immediately (within 5 CAD) prior to autoignition. Unlike previous studies, flames were not observed for all SA conditions. During SA operation, more fuel mass was burned by flame propagation with gasoline compared to E30.

  11. Development of High Efficiency Clean Combustion Engine Designs for Spark-Ignition and Compression-Ignition Internal Combustion Engines

    Energy Technology Data Exchange (ETDEWEB)

    Marriott, Craig; Gonzalez, Manual; Russell, Durrett

    2011-06-30

    such as internal dilution level and charge temperature. As a result, HCCI combustion has limited robustness when variables exceed the required narrow ranges determined in this program. HCCI combustion is also not available for the entire range of production engine speeds and loads, (i.e., the dynamic range is limited). Thus, regular SI combustion must be employed for a majority of the full dynamic range of the engine. This degrades the potential fuel economy impact of HCCI combustion. Currently-available combustion control actuators for the simple valve train system engine do not have the authority for continuous air - fuel or torque control for managing the combustion mode transitions between SI and HCCI and thus, require further refinement to meet customer refinement expectations. HCCI combustion control sensors require further development to enable robust long-term HCCI combustion control. Finally, the added technologies required to effectively manage HCCI combustion such as electric cam phasers, central direct fuel injection, cylinder pressure sensing, high-flow exhaust gas recirculation system, etc. add excessive on-engine cost and complexity that erodes the production-viability business

  12. High Efficiency, Low Emissions Homogeneous Charge Compression Ignition (HCCI) Engines

    Energy Technology Data Exchange (ETDEWEB)

    Gravel, Roland [U.S. Department of Energy' s Vehicle Technologies Office, Washington, DC (United States); Maronde, Carl [National Energy Technology Lab. (NETL), Albany, OR (United States); Gehrke, Chris [Caterpillar, Inc., Peoria, IL (United States); Fiveland, Scott [Caterpillar, Inc., Peoria, IL (United States)

    2010-10-30

    This is the final report of the High Efficiency Clean Combustion (HECC) Research Program for the U.S. Department of Energy. Work under this co-funded program began in August 2005 and finished in July 2010. The objective of this program was to develop and demonstrate a low emission, high thermal efficiency engine system that met 2010 EPA heavy-duty on-highway truck emissions requirements (0.2g/bhp-hr NOx, 0.14g/bhp-hr HC and 0.01g/bhp-hr PM) with a thermal efficiency of 46%. To achieve this goal, development of diesel homogenous charge compression ignition (HCCI) combustion was the chosen approach. This report summarizes the development of diesel HCCI combustion and associated enabling technologies that occurred during the HECC program between August 2005 and July 2010. This program showed that although diesel HCCI with conventional US diesel fuel was not a feasible means to achieve the program objectives, the HCCI load range could be increased with a higher volatility, lower cetane number fuel, such as gasoline, if the combustion rate could be moderated to avoid excessive cylinder pressure rise rates. Given the potential efficiency and emissions benefits, continued research of combustion with low cetane number fuels and the effects of fuel distillation are recommended. The operation of diesel HCCI was only feasible at part-load due to a limited fuel injection window. A 4% fuel consumption benefit versus conventional, low-temperature combustion was realized over the achievable operating range. Several enabling technologies were developed under this program that also benefited non-HCCI combustion. The development of a 300MPa fuel injector enabled the development of extended lifted flame combustion. A design methodology for minimizing the heat transfer to jacket water, known as precision cooling, will benefit conventional combustion engines, as well as HCCI engines. An advanced combustion control system based on cylinder pressure measurements was developed. A Well

  13. Miniature free-piston homogeneous charge compression ignition engine-compressor concept - Part II: modeling HCCI combustion in small scales with detailed homogeneous gas phase chemical kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Aichlmayr, H.T.; Kittelson, D.B.; Zachariah, M.R. [The University of Minnesota, Minneapolis (United States). Departments of Mechanical Engineering and Chemistry

    2002-10-01

    Operational maps for crankshaft-equipped miniature homogeneous charge compression ignition engines are established using performance estimation, detailed chemical kinetics, and diffusion models for heat transfer and radical loss. In this study, radical loss was found to be insignificant. In contrast, heat transfer was found to be increasingly significant for 10, 1, and 0.1 W engines, respectively. Also, temperature-pressure trajectories and ignition delay time maps are used to explore relationships between engine operational parameters and HCCI. Lastly, effects of engine operating conditions and design on the indicated fuel conversion efficiency are investigated. (author)

  14. HCCI gasoline engine by General Motors; Ottomotor mit HCCI-Technik von General Motors

    Energy Technology Data Exchange (ETDEWEB)

    Backhaus, R.

    2008-06-15

    General Motors recently presented the HCCI combustion process with cylinder pressure based engine control. A variable valve drive controls the residual gas fraction, and direct injection levels cylinder differences. A calinder pressure sensor system with robust engine control is necessary according to GM for adjusting the 50 mass fraction burnt for maximum efficiency and to compensate the influence of uncontrollable boundary conditions in real operation. (orig.)

  15. New Ignited Mode of Engine-Homogeneous Charge Compression Ignition(HCCI)%新的发动机燃烧方式--均质充量压燃燃烧(HCCI)

    Institute of Scientific and Technical Information of China (English)

    姜春生; 刘凤军

    2005-01-01

    在往复式发动机中,除了火花点燃式燃烧和柴油压燃燃烧的运转方式外还有第3种运转方式,即均质充量压燃燃烧(HCCI).HCCI模式发动机的运转情况被认为是高效和稳定的.在部分负荷工况下可以大幅度降低NOx的排放.把HCCI燃烧应用到发动机方面尽管仍有一些困难,但HCCI燃烧方式表明在发动机应用的巨大潜力.本文将阐述HCCI与传统发动机燃烧方式的不同及其未来的展望.

  16. Experimental and numerical analysis of the performance and exhaust gas emissions of a biogas/n-heptane fueled HCCI engine

    KAUST Repository

    Kozarac, Darko

    2016-09-12

    The use of highly reactive fuel as an ignition promoter enables operation of biogas fueled homogeneous charge compression ignition (HCCI) engine at low intake temperatures with practical control of combustion phasing. In order to gain some insight into this operation mode the influence of addition of n-heptane on combustion, performance, emissions and control of combustion phasing of a biogas fueled HCCI engine is experimentally researched and presented in this paper. Additionally, the performance analysis of the practical engine solution for such operation is estimated by using the numerical simulation of entire engine. The results showed that the introduction of highly reactive fuel results with a significant change in operating conditions and with a change in optimum combustion phasing. The addition of n-heptane resulted in lower nitrogen oxides and increased carbon monoxide emissions, while the unburned hydrocarbons emissions were strongly influenced by combustion phasing and at optimal conditions are lowered compared to pure biogas operation. The results also showed a practical operation range for strategies that use equivalence ratio as a control of load. Simulation results showed that the difference in performance between pure biogas and n-heptane/biogas operation is even greater when the practical engine solution is taken into account.

  17. 基于循环的瞬态空燃比对乙醇HCCI发动机燃烧特性的影响%Effects of Cyclic Real Time Air/Fuel Ratios on Combustion Characteristics in an Ethanol DI-HCCI Engine

    Institute of Scientific and Technical Information of China (English)

    邓俊; 刘寅童; 吴志军; 胡宗杰; 李理光

    2013-01-01

    均质充量压燃(HCCI)技术对于燃烧循环间变动较敏感,且循环间的瞬态空燃比对燃烧特性有重要影响.在缸内直喷HCCI发动机试验台架上,利用瞬态CO/CO2排放测试仪,对乙醇HCCI燃烧循环间瞬态空燃比进行检测,并将瞬态空燃比与燃烧特性参数进行对比分析.结果表明,连续循环的瞬态空燃比变化较明显,在其平均值附近波动且服从正态分布规律.由于乙醇汽化潜热高,喷油量增加引起的瞬态温度下降会导致燃烧相位后移,燃烧持续期延长.%HCCI combustion is much sensitive to cyclic variations. The transient air/fuel ratio has an important effect on combustion characteristics. Fast CO2/C(X HC and NOx measurement systems were employed to detect the transient emissions and real time air/fuel ratio of an ethanol fueled DI-HCCI. Effect of real time air/fuel ratio on combustion characteristics was analyzed. Results show that real time air/fuel ratio of continuous combustion cycles fluctuates to the averaged value and follows the normal distribution. For high latent heat of ethanol, the decreasing of temperature by increasing fuel injection quantity postpones combustion phase and increases combustion duration.

  18. Numerical simulation research of HCCI diesel engine combustion process%HCCI柴油机燃烧过程数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    李从心; 张欣; 孟金喆

    2006-01-01

    均质压燃(HCCI: homgeneous charge compression ignition)燃烧方式已成为发动机领域的硬件研究热点.针对CA4D32-09型柴油机,对HCCI燃烧过程进行了计算模拟,并利用统计的方法对影响HCCI燃烧特性的因素进行分析,通过计算得出HCCI发动机燃烧过程的影响因素及发动机主要参数对混合气均质特性的作用.

  19. RESEARCH ON COMBUSTION CHARACTERISTICS OF HCCI BASED ON GASOLINE DIRECT INJECTION%基于缸内直喷的汽油HCCI燃烧特性的研究

    Institute of Scientific and Technical Information of China (English)

    王建昕; 帅石金; 王志

    2008-01-01

    实现汽油机的均质混合气压燃(HCCI)的难点是精确地控制着火时刻、燃烧速率以及扩展高负荷运行范围.在缸内直喷汽油机(GDI)上试验研究了分层混合气和辅助火花点火对HCCI燃烧特性的影响,考察了对不同运行工况时的适应性.开展了负阀重叠与缸内多段喷油相结合控制HCCI着火稳定性的研究,考察了不同喷油控制策略对HCCI燃烧的影响,确定了HCCI运行工况范围.

  20. 柴油机HCCI燃烧的均质混合气制备%Preparation of Homogeneous Gas Mixture for Diesel Engine HCCI Combustion

    Institute of Scientific and Technical Information of China (English)

    李棠; 李理光

    2004-01-01

    介绍了均质充量压缩着火燃烧的概念、优缺点及其良好的发展前途与当前面临的困难.分析了HCCI混合气制备的重要性,总结了柴油机HCCI混合气制备的典型方法和成功经验,并分析了混合气制备对HCCI燃烧排放、着火相位的控制以及功率输出的影响,探讨并展望了HCCI混合气制备的可能发展方向.

  1. 基于可变技术的均质充量压缩着火燃烧控制%Variable Technology in HCCI Combustion Control

    Institute of Scientific and Technical Information of China (English)

    邓俊; 胡宗杰; 于水; 栗工; 李理光

    2004-01-01

    均质充量压缩着火(HCCI)是目前发动机领域的研究热点之一.通过分析可变技术对HCCI着火燃烧相位控制的原理及其国内外的研究进展,为实现HCCI成功应用及扩大HCCI功率及转速范围探寻切实可行的方案.分析表明,综合利用可变技术是在更大范围内实现HCCI稳定燃烧、扩大HCCI燃烧功率输出的主要发展方向.

  2. Effects of intake air temperature on homogenous charge compression ignition combustion and emissions with gasoline and n-heptane

    Directory of Open Access Journals (Sweden)

    Zhang Jianyong

    2015-01-01

    Full Text Available In a port fuel injection engine, Optimized kinetic process (OKP technology is implemented to realize HCCI combustion with dual-fuel injection. The effects of intake air temperature on HCCI combustion and emissions are investigated. The results show that dual-fuel control prolongs HCCI combustion duration and improves combustion stability. Dual-fuel HCCI combustion needs lower intake air temperature than gasoline HCCI combustion, which reduces the requirements on heat management system. As intake air temperature decreases, air charge increases and maximum pressure rising rate decreases. When intake air temperature is about 55ºC, HCCI combustion becomes worse and misfire happens. In fixed dual fuel content condition, HC and CO emission decreases as intake air temperature increases. The combination of dual-fuel injection and intake air temperature control can expand operation range of HCCI combustion.

  3. Influence of methanol on gasoline fuel HCCI combustion and emission mechanism%甲醇对汽油燃料均质压燃燃烧和排放机理的影响

    Institute of Scientific and Technical Information of China (English)

    吴威龙; 郑朝蕾; 胡林海

    2012-01-01

    为了探讨甲醇对汽油均质压燃( HCCI)燃烧和排放机理的影响,利用CHEMKIN软件从理论上研究了甲醇对汽油HCCI燃烧反应动力学机理的影响.结果表明:甲醇抑制了汽油(甲苯参比燃料)各组分的二次加氧过程,异辛烷基和正庚烷基继续脱氢,再氧化分解产生甲醛;甲苯基则直接氧化分解产生甲醛.随着甲醇体积分数增大,放热开始时刻提前,高温反应阶段的放热率峰值呈先增大后减小趋势.因此,可以通过调整反应中燃料的比例来控制着火时刻和放热峰值.CO和HC摩尔分数随甲醇比例增大逐步减小.随着燃空当量比升高,主燃烧峰值升高,主燃烧持续期延长,OH基生成速率和摩尔分数峰值增大,但放热开始时刻和OH开始生成时刻几乎不变.所以改变当量比可以改变燃烧反应中自由基摩尔分数和反应持续时间,但不能控制着火时刻.CO和HC摩尔分数峰值随当量比增大逐步增大,当量比过小时,大量CO和HC未被氧化.%The influence of methanol on the gasoline fuel HCCI ( homogeneous charge compression ignition) combustion and emission mechanism was investigated by CHEMKIN software. The results show that methanol inhibits the second oxygenation process for the components of gasoline. Isooctyl-alkyl and heptanes-alkyl keep on dehydrogenation, which are then oxidized to become formaldehyde. Tolyl is directly oxidized to be formaldehyde. As the proportion of methanol molar fraction increases, the start time of heat release is advanced, and the peak of heat release rate is increased firstly and then decreased in the high temperature phase. Thus, the ignition time and the peak of heat release can be controlled by adjusting the fuel ratio. CO and HC molar fraction decrease gradually with the increasing of methanol concentration. With the increasing of fuel air equivalence ratio, the main combustion peak increases, the main combustion duration extends, and the production rate

  4. 柴油机HCCI燃烧特点及影响因素分析%Characters of Diesel Engine HCCI Combustion and Analysis on Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    杜宝杰; 李岳林; 王立标; 汤彬

    2008-01-01

    均质充量压缩燃烧HCCI(Homogenous charge Compression Ignition)是一种新型发动机燃烧方式,它能有效地解决传统柴油机燃油经济性差和尾气排放高的问题,特别是能够降低Nox和PM的排放,并进一步提高热效率.柴油机的HCCI燃烧存在HC和CO排放偏高的问题,有待进一步降低,并且由于HCCI燃烧存在的燃烧控制以及适用工况范围窄等问题,因而目前柴油HCCI发动机还未能实现大规模商品化.介绍柴油机HCCI燃烧的特点以及影响柴油机HCCI燃烧的一些重要因素,如EGR、进气温度、压缩比ε、喷油时刻、燃空当量比和喷油压力等对柴油机HCCI燃烧和排放的影响.

  5. Longitudinal-Mode Combustion Instabilities: Modeling and Experiments

    Science.gov (United States)

    Cohen, J. M.; Hibshman, J. R.; Proscia, W.; Rosfjord, T. J.; Wake, B. E.; McVey, J. B.; Lovett, J.; Ondas, M.; DeLaat, J.; Breisacher, K.

    2000-01-01

    Combustion instabilities can lead to increased development time and cost for aeroengine gas turbines. This problem has been evident in the development of very-low emissions stationary gas turbines, and will likely be encountered in the newer, more aggressive aeroengine designs. In order to minimize development time and cost, it is imperative that potential combustion dynamics issues be resolved using analyses and smaller-scale experimentation. This paper discusses a methodology through which a problem in a full-scale engine was replicated in a single-nozzle laboratory combustor. Specifically, this approach is valid for longitudinal and "bulk" mode combustion instabilities. An explanation and partial validation of the acoustic analyses that were used to achieve this replication are also included. This approach yields a testbed for the diagnosis of combustion dynamics problems and for their solution through passive and active control techniques.

  6. Expanding Robust HCCI Operation with Advanced Valve and Fuel Control Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Szybist, J. P. [Oak Ridge National Lab., Oak Ridge, TN (United States); Confer, K. [Delphi Automotive Systems (United States)

    2012-09-11

    Delphi Automotive Systems and ORNL established this CRADA to advance the commercialization potential of the homogeneous charge compression ignition (HCCI) advanced combustion strategy for gasoline engine platforms. HCCI combustion has been shown by others to produce high diesel-like efficiency on a gasoline engine platform while simultaneously producing low NOX and particulate matter emissions. However, the commercialization barriers that face HCCI combustion are significant, with requirements for a more active engine control system, likely with next-cycle closed-loop feedback control, and with advanced valve train technologies to enable negative valve overlap conditions. In the partnership between Delphi and ORNL, each organization brought a unique and complementary set of skills to the project. Delphi has made a number of breakthroughs with production-intent valve train technologies and controls in recent years to make a part time production-intent HCCI engine plausible. ORNL has extensive knowledge and expertise with HCCI combustion, and also has a versatile research engine with hydraulic valve actuation (HVA) that is useful for guiding production of a cam-based HCCI system. Partnering these knowledge bases and capabilities was essential towards making progress to better understand HCCI combustion and the commercialization barriers that it faces. ORNL and Delphi maintained strong collaboration throughout the project. Meetings were held regularly, with additional reports, presentations, and meetings as necessary to maintain progress. Delphi provided guidance to ORNL regarding operational strategies to investigate on their single-cylinder research engine with HVA and data from their experimental multi-cylinder engine for modeling. ORNL provided single-cylinder engine data and modeling results.

  7. Identification of the dynamic operating envelope of HCCI engines using class imbalance learning.

    Science.gov (United States)

    Janakiraman, Vijay Manikandan; Nguyen, XuanLong; Sterniak, Jeff; Assanis, Dennis

    2015-01-01

    Homogeneous charge compression ignition (HCCI) is a futuristic automotive engine technology that can significantly improve fuel economy and reduce emissions. HCCI engine operation is constrained by combustion instabilities, such as knock, ringing, misfires, high-variability combustion, and so on, and it becomes important to identify the operating envelope defined by these constraints for use in engine diagnostics and controller design. HCCI combustion is dominated by complex nonlinear dynamics, and a first-principle-based dynamic modeling of the operating envelope becomes intractable. In this paper, a machine learning approach is presented to identify the stable operating envelope of HCCI combustion, by learning directly from the experimental data. Stability is defined using thresholds on combustion features obtained from engine in-cylinder pressure measurements. This paper considers instabilities arising from engine misfire and high-variability combustion. A gasoline HCCI engine is used for generating stable and unstable data observations. Owing to an imbalance in class proportions in the data set, the models are developed both based on resampling the data set (by undersampling and oversampling) and based on a cost-sensitive learning method (by overweighting the minority class relative to the majority class observations). Support vector machines (SVMs) and recently developed extreme learning machines (ELM) are utilized for developing dynamic classifiers. The results compared against linear classification methods show that cost-sensitive nonlinear ELM and SVM classification algorithms are well suited for the problem. However, the SVM envelope model requires about 80% more parameters for an accuracy improvement of 3% compared with the ELM envelope model indicating that ELM models may be computationally suitable for the engine application. The proposed modeling approach shows that HCCI engine misfires and high-variability combustion can be predicted ahead of time

  8. The influence of charge stratification on the spectral signature of partially premixed combustion in a light-duty optical engine

    KAUST Repository

    Najafabadi, M. Izadi

    2017-03-25

    The origin of light emission during low-temperature combustion in a light-duty IC engine is investigated by high-speed spectroscopy in both HCCI and PPC regimes. Chemiluminescence and thermal radiation are expected to be the dominant sources of light emission during combustion. A method has been developed to distinguish chemiluminescence from thermal radiation, and different chemiluminescing species could be identified. Different combustion modes and global equivalence ratios are analyzed in this manner. The results indicate that the spectral signature (270–540 nm range) of the combustion is highly dependent on the stratification level. A significant broadband chemiluminescence signal is detected and superimposed on all spectra. This broadband chemiluminescence signal can reach up to 100 percent of the total signal in HCCI combustion, while it drops to around 80 percent for stratified combustion (PPC). We show that this broadband signal can be used as a measure for the heat release rate. The broadband chemiluminescence did also correlate with the equivalence ratio quite well in both HCCI and PPC regimes, suggesting that the total emission in the spectral region of 330–400 nm can serve as a proxy of equivalence ratio and the rate of heat release. Regarding C2* chemiluminescence, we see two different chemical mechanisms for formation of C2* in the PPC regime: first during the early stage of combustion by the breakup of bigger molecules and the second during the late stage of combustion when soot particles are forming.

  9. The influence of charge stratification on the spectral signature of partially premixed combustion in a light-duty optical engine

    Science.gov (United States)

    Najafabadi, M. Izadi; Egelmeers, Luc; Somers, Bart; Deen, Niels; Johansson, Bengt; Dam, Nico

    2017-04-01

    The origin of light emission during low-temperature combustion in a light-duty IC engine is investigated by high-speed spectroscopy in both HCCI and PPC regimes. Chemiluminescence and thermal radiation are expected to be the dominant sources of light emission during combustion. A method has been developed to distinguish chemiluminescence from thermal radiation, and different chemiluminescing species could be identified. Different combustion modes and global equivalence ratios are analyzed in this manner. The results indicate that the spectral signature (270-540 nm range) of the combustion is highly dependent on the stratification level. A significant broadband chemiluminescence signal is detected and superimposed on all spectra. This broadband chemiluminescence signal can reach up to 100 percent of the total signal in HCCI combustion, while it drops to around 80 percent for stratified combustion (PPC). We show that this broadband signal can be used as a measure for the heat release rate. The broadband chemiluminescence did also correlate with the equivalence ratio quite well in both HCCI and PPC regimes, suggesting that the total emission in the spectral region of 330-400 nm can serve as a proxy of equivalence ratio and the rate of heat release. Regarding C2* chemiluminescence, we see two different chemical mechanisms for formation of C2* in the PPC regime: first during the early stage of combustion by the breakup of bigger molecules and the second during the late stage of combustion when soot particles are forming.

  10. Experimental Investigation of the Effect of Mixed Additives on Homogeneous Charge Compression Ignition Combustion

    Institute of Scientific and Technical Information of China (English)

    LI Chao; JI Chang-wei; HE Chao; LI Yun-zhe; HE Hong; SHEN Zi-you

    2008-01-01

    The experimental investigation of homogeneous charge compression ignition (HCCI) process is carried out on a 4-cylinder diesel engine. One of the cylinders is modified for HCCI combustion with mixed additives. The influence of mixed additives on the HCCI combustion process is investigated. The experimental results indicate that the mixed additives are better than the single additives for HCCI fuel, causing ignition and heat release to be advanced and the peak of heat release rate to increase under the condition of different engine speeds and steady HCCI combustion. Moreover, with the increase in engine speed, the influence of mixed additives on HCCI combustion is more obvious. In addition, the mixed additives are beneficial to improve HCCI engine misfire at a high engine speed and make the engine operate stable.

  11. Lean homogenous combustion of E-diesel using external mixture formation technique

    Directory of Open Access Journals (Sweden)

    A. Avinash

    2015-09-01

    Full Text Available For the past one hundred years, lots of easily accessible petroleum fuel has been burned out by humankind in inefficient engines. In this regard, present-day engine researchers face a formidable challenge to achieve the goal of significant improvements in both thermal efficiency and fuel economy. Although the direction to reach this target is critical, homogenous charge compression ignition (HCCI is just another combustion concept to achieve this target. By the way, this work investigates the combustion phenomena of the HCCI engine by external mixture formation technique. In a nut-shell, an endeavor has been made in this work to prepare homogeneous mixture outside the combustion chamber using a fuel vaporizer system to form a uniform fuel–air mixture. The fundamental research experiments were carried out with vaporized diesel and vaporized e-diesel blends (10% and 20% ethanol substitution by volume, and the results were compared with conventional diesel engine operation. In HCCI mode, the maximum rate of pressure rises and the maximum rate of heat-release significantly reduced with increase of ethanol concentration in diesel. The experimental outcomes exposed that when HCCI engine is operated with e-diesel blend, smooth engine operation is apparent.

  12. A Review on Homogeneous Charge Compression Ignition and Low Temperature Combustion by Optical Diagnostics

    Directory of Open Access Journals (Sweden)

    Chao Jin

    2015-01-01

    Full Text Available Optical diagnostics is an effective method to understand the physical and chemical reaction processes in homogeneous charge compression ignition (HCCI and low temperature combustion (LTC modes. Based on optical diagnostics, the true process on mixing, combustion, and emissions can be seen directly. In this paper, the mixing process by port-injection and direct-injection are reviewed firstly. Then, the combustion chemical reaction mechanism is reviewed based on chemiluminescence, natural-luminosity, and laser diagnostics. After, the evolution of pollutant emissions measured by different laser diagnostic methods is reviewed and the measured species including NO, soot, UHC, and CO. Finally, a summary and the future directions on HCCI and LTC used optical diagnostics are presented.

  13. Homogeneous charge compression ignition (HCCI) - A comparison with spark ignition (SI) operation

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Magnus

    1997-08-01

    Homogeneous Charge Compression Ignition (HCCI) is the third alternative for combustion in engines. Here a homogeneous premixed charge is used as in a spark ignited engine but the charge is compressed to auto-ignition as in a diesel. The characteristics of HCCI was compared to spark ignition (SI) using a 1.6 liter single cylinder engine. Three different fuels were used; isooctane, ethanol and natural gas. HCCI could be used with all three fuels in a single cylinder engine with a fixed compression ratio. Some remarkable results were noted in the experiments. The indicated efficiency of HCCI was much better than for SI operation. The gross indicated efficiency showed values at 50% for the richer cases. This means that the fuel consumption at part load would be reduced to the half compared to SI operation. Very little NO{sub x} was generated with HCCI, only a few ppm. With isooctane, it ranged from 4 to below 1 ppm and with ethanol even lower values. However, HCCI generated more HC and CO. Operation was noisier with HCCI than with SI. Stable and efficient operation with HCCI could be obtained with {lambda} = 3.5 to 9 using isooctane, 3.5 to 6.5 using ethanol, and 2.5 to 3.5 using natural gas. Cycle to cycle variation of combustion was very low. Isooctane could be operated unthrottled without preheating. The selection of the high compression ratio, 21:1, was dependent on the high octane number for natural gas. The attainable IMEP was 5 bar. The limit to make higher IMEP was the rate of combustion. At IMEP 5 bar the main combustion, 10-90% burn duration, took place in less than 2 crank angle degrees (CAD). This is extremely fast and gives very high rate of pressure rise, which leads to noisy operation and high loads on the engine. The lean limit was given by unstable combustion with cycle to cycle variation of combustion, and with high emissions of unburned hydrocarbons and carbon monoxide Examination paper. 15 refs, 38 figs, 1 tab

  14. 催化燃烧对均质压燃发动机燃烧特性影响的数值模拟%Numerical Simulation of the Influences of Catalytic Combustion on HCCI Engine Combustion Characteristics

    Institute of Scientific and Technical Information of China (English)

    曾文; 解茂昭; 贾明

    2006-01-01

    通过运用DETCHEM软件包,对甲烷在催化剂Rh表面的详细反应机理进行了分析,结果表明数值模拟结果与实验数据相当吻合;通过耦合DETCHEM软件包及CHEMKIN软件包中的SENKIN模块,对活塞顶涂有催化剂铑的均质压燃(HCCI)发动机的燃烧过程进行了数值计算,建立了单区和多区模型.利用单区模型分析了催化燃烧对HCCI发动机着火时刻的影响,同时讨论了催化燃烧对燃烧过程中主要化学组分浓度变化的影响,结果表明催化燃烧会使HCCI发动机着火时刻提前;利用多区模型分析了催化燃烧对HCCI发动机的未燃碳氢化合物(UHC)、氮氧化合物(NOx)排放的影响,结果表明催化燃烧能降低UHC的排放,但会提高NOx的排放.

  15. Experimental Investigation on Extending Load Range of Diesel HCCI Engine by Internal EGR and Boost%内部EGR及增压拓展柴油HCCI燃烧负荷范围试验研究

    Institute of Scientific and Technical Information of China (English)

    桂勇; 孙佑成; 徐敏; 邓康耀; 石磊

    2012-01-01

    在135单缸柴油机上对比了传统燃烧模式和HCCI燃烧模式的负荷特性,优化了HCCI燃烧模式的喷油始点,分析了内部EGR率及增压压力对HCCI燃烧负荷范围及排放的影响.试验结果表明:对于负气门重叠期喷油的HCCI燃烧模式,1 500 r/min下,最佳喷油始点为370°BTDC,气门重叠期为-30°时既保证了较低的NOx排放,又可以获得较佳的负荷范围;提高增压压力不仅可以拓展HCCI燃烧的负荷上限,对负荷下限的燃烧稳定性也有利;将增压压力提高到0.18 MPa时,负荷上限从传统燃烧的0.594 MPa上升到0.723 MPa,但负荷下限较传统燃烧模式要高,CO排放、烟度和燃油经济性都较差.%On a single cylinder diesel engine, the load characteristics between traditional combustion and HCCI combustion were compared, the injection timing of HCCI was optimized and the influences of internal EGR rate and boost pressure on HCCI combustion load range and emissions were analyzed. The results show that the best injection timing of HCCI mode with the negative valve overlap at 1500 r/min is 370°BTDC. The - 30° valve overlap can guarantee lower NOx emission and better load range. The increase of boost pressure extends the upper load limit of HCCI combustion and is beneficial to the combustion stability of lower load limit. Improving the boost pressure on 0.18 MPa, the upper load limit increases from 0. 594 MPa to 0. 723 MPa, but lower load limit also increases, which gives worse CO emission, smoke and fuel economy.

  16. Mode Selection in Flame-Vortex driven Combustion Instabilities

    KAUST Repository

    Speth, Ray

    2011-01-04

    In this paper, we investigate flame-vortex interaction in a lean premixed, laboratory scale, backward-facing step combustor. Two series of tests were conducted, using propane/hydrogen mixtures and carbon monoxide/hydrogen mixtures as fuels, respectively. Pressure measurements and high speed particle imaging velocimetry (PIV) were employed to generate pressure response curves as well as the images of the velocity field and the flame brush. We demonstrate that the step combustor exhibits several operating modes depending on the inlet conditions and fuel composition, characterized by the amplitude and frequency of pressure oscillations along with distinct dynamic flame shapes. We propose a model in which the combustor\\'s selection of the acoustic mode is governed by a combustion-related time delay inversely proportional to the flame speed. Our model predicts the transition between distinct operating modes. We introduce non-dimensional parameters characterizing the flame speed and stretch rate, and develop a relationship between these quantities at the operating conditions corresponding to each mode transition. Based on this relationship, we show that numerically-calculated density-weighted strained flame speed can be used to collapse the combustion dynamics data over the full range of conditions (inlet temperature, fuel composition, and equivalence ratio). Finally, we validate our strain flame based model by measuring the strain rate using the flame image and the velocity field from the PIV measurement. Our results show that the measured strain rates lie in the same range as the critical values at the transitions among distinct modes as those predicted by our model.

  17. A Comprehensive Numerical Study on Effects of Natural Gas Composition on the Operation of an HCCI Engine Une étude numérique complète sur les effets de la composition du gaz naturel carburant sur le réglage d’un moteur HCCI

    Directory of Open Access Journals (Sweden)

    Jahanian O.

    2011-11-01

    Full Text Available Homogeneous Charge Compression Ignition (HCCI engine is a promising idea to reduce fuel consumption and engine emissions. Natural Gas (NG, usually referred as clean fuel, is an appropriate choice for HCCI engines due to its suitable capability of making homogenous mixture with air. However, varying composition of Natural Gas strongly affects the auto-ignition characteristics of in-cylinder mixture and the performance of the HCCI engine. This paper has focused on the influence of Natural Gas composition on engine operation in HCCI mode. Six different compositions of Natural Gas (including pure methane have been considered to study the engine performance via a thermo-kinetic zero-dimensional model. The simulation code covers the detailed chemical kinetics of Natural Gas combustion, which includes Zeldovich extended mechanism to evaluate NOx emission. Validations have been made using experimental data from other works to ensure the accuracy needed for comparison study. The equivalence ratio and the compression ratio are held constant but the engine speed and mixture initial temperature are changed for comparison study. Results show that the peak value of pressure/temperature of in-cylinder mixture is dependent of fuel Wobbe number. Furthermore, engine gross indicated power is linearly related to fuel Wobbe number. Gross indicated work, gross mean effective pressure, and NOx are the other parameters utilized to compare the performance of engine using different fuel compositions. Le moteur HCCI (Homogeneous Charge Compression Ignition, ou à allumage par compression d’une charge homogène est une idée prometteuse pour réduire la consommation de carburant et les émissions polluantes. Le gaz naturel, considéré généralement comme un carburant propre, est un choix approprié pour les moteurs HCCI en raison de sa capacité à former avec l’air un mélange homogène. Cependant, la composition du gaz naturel influe fortement sur les caract

  18. Three-stage autoignition of gasoline in an HCCI engine: An experimental and chemical kinetic modeling investigation

    Energy Technology Data Exchange (ETDEWEB)

    Machrafi, Hatim; Cavadias, Simeon [UPMC Universite Paris 06, LGPPTS, Ecole Nationale Superieure de Chimie de Paris (France); UPMC Universite Paris 06, Institut Jean Le Rond D' Alembert (France)

    2008-12-15

    The alternative HCCI combustion mode presents a possible means for decreasing the pollution with respect to conventional gasoline or diesel engines, while maintaining the efficiency of a diesel engine or even increasing it. This paper investigates the possibility of using gasoline in an HCCI engine and analyzes the autoignition of gasoline in such an engine. The compression ratio that has been used is 13.5, keeping the inlet temperature at 70 C, varying the equivalence ratio from 0.3 to 0.54, and the EGR (represented by N{sub 2}) ratio from 0 to 37 vol%. For comparison, a PRF95 and a surrogate containing 11 vol% n-heptane, 59 vol% iso-octane, and 30 vol% toluene are used. A previously validated kinetic surrogate mechanism is used to analyze the experiments and to yield possible explanations to kinetic phenomena. From this work, it seems quite possible to use the high octane-rated gasoline for autoignition purposes, even under lean inlet conditions. Furthermore, it appeared that gasoline and its surrogate, unlike PRF95, show a three-stage autoignition. Since the PRF95 does not contain toluene, it is suggested by the kinetic mechanism that the benzyl radical, issued from toluene, causes this so-defined ''obstructed preignition'' and delaying thereby the final ignition for gasoline and its surrogate. The results of the kinetic mechanism supporting this explanation are shown in this paper. (author)

  19. Experimental Investigation of Piston Heat Transfer in a Light Duty Engine Under Conventional Diesel, Homogeneous Charge Compression Ignition, and Reactivity Controlled Compression Ignition Combustion Regimes

    Science.gov (United States)

    2014-01-15

    engine speed and load conditions. The closed-cycle integrated and peak heat transfer rates were found to be lower for HCCI and RCCI when compared to...limit the load of HCCI due to practical engine limitations. Additionally, HCCI lacks a fast-response combustion phasing control, such as spark...cylinder research engine under Conventional Diesel (CDC), Homogeneous Charge Compression Ignition ( HCCI ), and Reactivity Controlled Compression Ignition

  20. DETAILED CHEMICAL KINETIC MODELING OF ISO-OCTANE SI-HCCI TRANSITION

    Energy Technology Data Exchange (ETDEWEB)

    Havstad, M A; Aceves, S M; McNenly, M J; Piggott, W T; Edwards, K D; Wagner, R M; Daw, C S; Finney, C A

    2009-10-12

    The authors describe a CHEMKIN-based multi-zone model that simulates the expected combustion variations in a single-cylinder engine fueled with iso-octane as the engine transitions from spark-ignited (ST) combustion to homogeneous charge compression ignition (HCCI) combustion. The model includes a 63-species reaction mechanism and mass and energy balances for the cylinder and the exhaust flow. For this study they assumed that the SI-to-HCCI transition is implemented by means of increasing the internal exhaust gas recirculation (EGR) at constant engine speed. This transition scneario is consistent with that implemented in previously reported experimental measurements on an experimental engine equipped with variable valve actuation. They find that the model captures many of the important experimental trends, including stable SI combustion at low EGR ({approx} 0.10), a transition to highly unstable combustion at intermediate EGR, and finally stable HCCI combustion at very high EGR ({approx} 0.75). Remaining differences between the predicted and experimental instability patterns indicate that there is further room for model improvement.

  1. Flow field characteristics analysis and combustion modes classification for a strut/cavity dual-mode combustor

    Science.gov (United States)

    Zhang, Chenlin; Chang, Juntao; Zhang, Yuanshi; Wang, Youyin; Bao, Wen

    2017-08-01

    Experimental and numerical study of a strut/cavity dual-mode combustor has been conducted in this paper. Under different fuel equivalence ratio and allocation proportion conditions, the pressure distribution and flow field structure of combustor show distinct characteristics. For strut fuel injecting at a low equivalence ratio, the luminosity images show that combustion zone distributes in the shear layer behind the strut. The wall fuel injecting before strut would change the starting point of pressure rising. Based on the flow field structure, the dual-mode combustor operation process is classified into three combustion modes, including scramjet mode, weak ramjet mode and strong ramjet mode. Because of a strong interaction of the shock wave with the boundary layer, weak ramjet mode has a stronger isolator compression effect and higher combustion efficiency than scramjet mode. With heat release increasing, the thermal throat formation is an indication of the strong ramjet mode, which has a subsonic gap in the isolator. Further, by judging the pressure from dominant pressure sensor before the strut, the three different combustion modes could be classified. Comparing the specific impulse of combustor, it has an obvious distinction in the different combustion modes.

  2. Evaluation of Technical Feasibility of Homogeneous Charge Compression Ignition (HCCI) Engine Fueled with Hydrogen, Natural Gas, and DME

    Energy Technology Data Exchange (ETDEWEB)

    John Pratapas; Daniel Mather; Anton Kozlovsky

    2007-03-31

    The objective of the proposed project was to confirm the feasibility of using blends of hydrogen and natural gas to improve the performance, efficiency, controllability and emissions of a homogeneous charge compression ignition (HCCI) engine. The project team utilized both engine simulation and laboratory testing to evaluate and optimize how blends of hydrogen and natural gas fuel might improve control of HCCI combustion. GTI utilized a state-of-the art single-cylinder engine test platform for the experimental work in the project. The testing was designed to evaluate the feasibility of extending the limits of HCCI engine performance (i.e., stable combustion, high efficiency and low emissions) on natural gas by using blends of natural gas and hydrogen. Early in the project Ricardo provided technical support to GTI as we applied their engine performance simulation program, WAVE, to our HCCI research engine. Modeling support was later provided by Digital Engines, LLC to use their proprietary model to predict peak pressures and temperatures for varying operating parameters included in the Design of Experiments test plan. Digital Engines also provided testing support for the hydrogen and natural gas blends. Prof. David Foster of University of Wisconsin-Madison participated early in the project by providing technical guidance on HCCI engine test plans and modeling requirements. The main purpose of the testing was to quantify the effects of hydrogen addition to natural gas HCCI. Directly comparing straight natural gas with the hydrogen enhanced test points is difficult due to the complexity of HCCI combustion. With the same air flow rate and lambda, the hydrogen enriched fuel mass flow rate is lower than the straight natural gas mass flow rate. However, the energy flow rate is higher for the hydrogen enriched fuel due to hydrogen's significantly greater lower heating value, 120 mJ/kg for hydrogen compared to 45 mJ/kg for natural gas. With these caveats in mind, an

  3. Application of exhaust gas fuel reforming in diesel and homogeneous charge compression ignition (HCCI) engines fuelled with biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Tsolakis, A. [School of Engineering, Mechanical and Manufacturing Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Megaritis, A. [Department of Mechanical Engineering, School of Engineering and Design, Brunel University, West London, Uxbridge UB8 3PH (United Kingdom); Yap, D. [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore)

    2008-03-15

    This paper documents the application of exhaust gas fuel reforming of two alternative fuels, biodiesel and bioethanol, in internal combustion engines. The exhaust gas fuel reforming process is a method of on-board production of hydrogen-rich gas by catalytic reaction of fuel and engine exhaust gas. The benefits of exhaust gas fuel reforming have been demonstrated by adding simulated reformed gas to a diesel engine fuelled by a mixture of 50% ultra low sulphur diesel (ULSD) and 50% rapeseed methyl ester (RME) as well as to a homogeneous charge compression ignition (HCCI) engine fuelled by bioethanol. In the case of the biodiesel fuelled engine, a reduction of NO{sub x} emissions was achieved without considerable smoke increase. In the case of the bioethanol fuelled HCCI engine, the engine tolerance to exhaust gas recirculation (EGR) was extended and hence the typically high pressure rise rates of HCCI engines, associated with intense combustion noise, were reduced. (author)

  4. On Cyclic Variability in a Residual Effected HCCI Engine with Direct Gasoline Injection during Negative Valve Overlap

    Directory of Open Access Journals (Sweden)

    Jacek Hunicz

    2014-01-01

    Full Text Available This study contributes towards describing the nature of cycle-by-cycle variability in homogeneous charge compression ignition (HCCI engines. Experimental measurements were performed using a single cylinder research engine operated in the negative valve overlap (NVO mode and fuelled with direct gasoline injection. Both stoichiometric and lean mixtures were applied in order to distinguish between different exhaust-fuel reactions during the NVO period and their propagation into the main event combustion. The experimental results show that the mode of cycle-by-cycle variability depends on the NVO phenomena. Under stoichiometric mixture conditions, neither variability in the main event indicated mean effective pressure (IMEP nor the combustion timing was affected by the NVO phenomena; however, long period oscillations in IMEP were observed. In contrast, for lean mixture, where fuel oxidation during the NVO period took place, distinctive correlations between NVO phenomena and the main event combustion parameters were observed. A wavelet analysis revealed the presence of both long-term and short-term oscillations in IMEP, in accordance with the extent of NVO phenomena. Characteristic patterns in IMEP were recognized using an in-house algorithm.

  5. Homogeneous Charge Compression Ignition Combustion of Dimethyl Ether

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr

    This thesis is based on experimental and numerical studies on the use of dimethyl ether (DME) in the homogeneous charge compression ignition (HCCI) combustion process. The first paper in this thesis was published in 2007 and describes HCCI combustion of pure DME in a small diesel engine. The tests...... a substantial combustion delay in HCCI operation with DME to achieve post TDC combustion. By adding methanol to the inlet port during HCCI combustion of DME, the engine reached 50 percent of its full DI CI load capability without engine knock at 1000 rpm and somewhat less at 1800 rpm. The engine also had EGR...... were designed to investigate the effect of engine speed, compression ratio and equivalence ratio on the combustion timing and the engine performance. It was found that the required compression ratio depended on the equivalence ratio used. A lower equivalence ratio requires a higher compression ratio...

  6. New Combustion Technology on Homogeneous Charge Compression Ignition%均质压燃在内燃机燃烧技术中的应用

    Institute of Scientific and Technical Information of China (English)

    周晶磊; 夏鸿文; 任超伟

    2013-01-01

    均质压燃(HCCI)是一种新的燃烧方式,它是预混混合气在压缩过程中温度升高达到自燃温度以后发生的燃烧现象。本文阐述了“均质压燃、低温燃烧”新一代内燃机燃烧技术的背景、研究现状以及所取得的主要研究进展。%With the rapid development of national economy, there are a lot of automobiles in China. The main power devices of automobiles are internal combustion engines, which faces more challenges, such as energy saving and environmental protection. But these challenges are advantageous to improve automo-tive technologies and spur a new generation, energy saving and low emission cars to appear. HCCI (Homo-geneous Charge Compression Ignition) is a new kind of combustion mode, which is the autoignition of pre-mixtures when their temperature is high enough to self-ignition by compression. This combustion can reduce the emission of NOX and particulate matters, in addition, use many fuel, so HCCI has been a research hot spot in internal combustion engine field.This paper focuses on the background, the technical route and the key scientific advances and achievements of new combustion technology on the Homogeneous Charge Compression Ignition (HCCI) .

  7. Homogeneous Charge Compression Ignition Combustion: Challenges and Proposed Solutions

    Directory of Open Access Journals (Sweden)

    Mohammad Izadi Najafabadi

    2013-01-01

    Full Text Available Engine and car manufacturers are experiencing the demand concerning fuel efficiency and low emissions from both consumers and governments. Homogeneous charge compression ignition (HCCI is an alternative combustion technology that is cleaner and more efficient than the other types of combustion. Although the thermal efficiency and NOx emission of HCCI engine are greater in comparison with traditional engines, HCCI combustion has several main difficulties such as controlling of ignition timing, limited power output, and weak cold-start capability. In this study a literature review on HCCI engine has been performed and HCCI challenges and proposed solutions have been investigated from the point view of Ignition Timing that is the main problem of this engine. HCCI challenges are investigated by many IC engine researchers during the last decade, but practical solutions have not been presented for a fully HCCI engine. Some of the solutions are slow response time and some of them are technically difficult to implement. So it seems that fully HCCI engine needs more investigation to meet its mass-production and the future research and application should be considered as part of an effort to achieve low-temperature combustion in a wide range of operating conditions in an IC engine.

  8. Homogeneous Charge Compression Ignition Combustion of Dimethyl Ether

    OpenAIRE

    Pedersen, Troels Dyhr; Schramm, Jesper

    2011-01-01

    This thesis is based on experimental and numerical studies on the use of dimethyl ether (DME) in the homogeneous charge compression ignition (HCCI) combustion process. The first paper in this thesis was published in 2007 and describes HCCI combustion of pure DME in a small diesel engine. The tests were designed to investigate the effect of engine speed, compression ratio and equivalence ratio on the combustion timing and the engine performance. It was found that the required compression ratio...

  9. Evaluation of Technical Feasibility of Homogeneous Charge Compression Ignition (HCCI) Engine Fueled with Hydrogen, Natural Gas, and DME

    Energy Technology Data Exchange (ETDEWEB)

    Pratapas, John; Mather, Daniel; Kozlovsky, Anton

    2013-03-31

    The objective of the proposed project was to confirm the feasibility of using blends of hydrogen and natural gas to improve the performance, efficiency, controllability and emissions of a homogeneous charge compression ignition (HCCI) engine. The project team utilized both engine simulation and laboratory testing to evaluate and optimize how blends of hydrogen and natural gas fuel might improve control of HCCI combustion. GTI utilized a state-of-the art single-cylinder engine test platform for the experimental work in the project. The testing was designed to evaluate the feasibility of extending the limits of HCCI engine performance (i.e., stable combustion, high efficiency and low emissions) on natural gas by using blends of natural gas and hydrogen. Early in the project Ricardo provided technical support to GTI as we applied their engine performance simulation program, WAVE, to our HCCI research engine. Modeling support was later provided by Digital Engines, LLC to use their proprietary model to predict peak pressures and temperatures for varying operating parameters included in the Design of Experiments test plan. Digital Engines also provided testing support for the hydrogen and natural gas blends. Prof. David Foster of University of Wisconsin-Madison participated early in the project by providing technical guidance on HCCI engine test plans and modeling requirements. The main purpose of the testing was to quantify the effects of hydrogen addition to natural gas HCCI. Directly comparing straight natural gas with the hydrogen enhanced test points is difficult due to the complexity of HCCI combustion. With the same air flow rate and lambda, the hydrogen enriched fuel mass flow rate is lower than the straight natural gas mass flow rate. However, the energy flow rate is higher for the hydrogen enriched fuel due to hydrogen’s significantly greater lower heating value, 120 mJ/kg for hydrogen compared to 45 mJ/kg for natural gas. With these caveats in mind, an

  10. 混合气质量对乙醇发动机均质压燃燃烧特性的影响%Influence of mixture quality on HCCI combustion characteristics of ethanol engine

    Institute of Scientific and Technical Information of China (English)

    杨立平; 郭英男; 李君; 刘金山; 王立媛

    2008-01-01

    在一台经改造而成的单缸均质压燃(HCCI)发动机上,以乙醇为燃料研究了不同循环供油量和废气再循环(EGR)率对HCCI燃烧的动力性、经济性和排放性的影响.结果表明:乙醇燃料HCCI燃烧有较高的指示热效率,最高可以接近60%;最高平均指示压力Pmi为0.6MPa;过量空气系数φa和EGR率的合理组合可以有效控制HCCI燃烧的着火正时和NOx排放,但是EGR的加入会导致HC和CO排放增加.

  11. Development of the RIOT web service and information technologies to enable mechanism reduction for HCCI simulations

    Science.gov (United States)

    Schuchardt, Karen; Oluwole, Oluwayemisi; Pitz, William; Rahn, Larry A.; Green, William H., Jr.; Leahy, David; Pancerella, Carmen; Sjöberg, Magnus; Dec, John

    2005-01-01

    New approaches are being explored to facilitate multidisciplinary collaborative research of Homogenous Charge Compression Ignition (HCCI) combustion processes. In this paper, collaborative sharing of the Range Identification and Optimization Toolkit (RIOT) and related data and models is discussed. RIOT is a developmental approach to reduce the computational complexity of detailed chemical kinetic mechanisms, enabling their use in modeling kinetically controlled combustion applications such as HCCI. These approaches are being developed and piloted as a part of the Collaboratory for Multiscale Chemical Sciences (CMCS) project. The capabilities of the RIOT code are shared through a portlet in the CMCS portal that allows easy specification and processing of RIOT inputs, remote execution of RIOT, tracking of data pedigree, and translation of RIOT outputs to a table view and to a commonly-used chemical model format.

  12. Development of the RIOT Web Service and Information Technologies to Enable Mechanism Reduction for HCCI Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Schuchardt, K; Oluwole, O; Pitz, W J; Rahn, L; Green, W H; Leahy, D; Pancerella, C; Sj?berg, M; Dec, J

    2005-06-13

    New approaches are being explored to facilitate multidisciplinary collaborative research of Homogeneous Charge Compression Ignition (HCCI) combustion processes. In this paper, collaborative sharing of the Range Identification and Optimization Toolkit (RIOT) and related data and models is discussed. RIOT is a developmental approach to reduce the computational of detailed chemical kinetic mechanisms, enabling their use in modeling kinetically controlled combustion applications such as HCCI. These approaches are being developed and piloted as a part of the Collaboratory for Multiscale Chemical Sciences (CMCS) project. The capabilities of the RIOT code are shared through a portlet in the CMCS portal that allows easy specification and processing of RIOT inputs, remote execution of RIOT, tracking of data pedigree, and translation of RIOT outputs to a table view and to a commonly-used mechanism format.

  13. Fuels and Combustion

    KAUST Repository

    Johansson, Bengt

    2016-08-17

    This chapter discusses the combustion processes and the link to the fuel properties that are suitable for them. It describes the basic three concepts, including spark ignition (SI) and compression ignition (CI), and homogeneous charge compression ignition (HCCI). The fuel used in a CI engine is vastly different from that in an SI engine. In an SI engine, the fuel should sustain high pressure and temperature without autoignition. Apart from the dominating SI and CI engines, it is also possible to operate with a type of combustion: autoignition. With HCCI, the fuel and air are fully premixed before combustion as in the SI engine, but combustion is started by the increased pressure and temperature during the compression stroke. Apart from the three combustion processes, there are also a few combined or intermediate concepts, such as Spark-Assisted Compression Ignition (SACI). Those concepts are discussed in terms of the requirements of fuel properties.

  14. Longitudinal Mode Aeroengine Combustion Instability: Model and Experiment

    Science.gov (United States)

    Cohen, J. M.; Hibshman, J. R.; Proscia, W.; Rosfjord, T. J.; Wake, B. E.; McVey, J. B.; Lovett, J.; Ondas, M.; DeLaat, J.; Breisacher, K.

    2001-01-01

    Combustion instabilities in gas turbine engines are most frequently encountered during the late phases of engine development, at which point they are difficult and expensive to fix. The ability to replicate an engine-traceable combustion instability in a laboratory-scale experiment offers the opportunity to economically diagnose the problem more completely (to determine the root cause), and to investigate solutions to the problem, such as active control. The development and validation of active combustion instability control requires that the casual dynamic processes be reproduced in experimental test facilities which can be used as a test bed for control system evaluation. This paper discusses the process through which a laboratory-scale experiment and be designed to replicate an instability observed in a developmental engine. The scaling process used physically-based analyses to preserve the relevant geometric, acoustic, and thermo-fluid features, ensuring that results achieved in the single-nozzle experiment will be scalable to the engine.

  15. Knock Sensor Signal and Instant Speed-Based Observer of Gasoline Engine HCCI Combustion Phasing CA10%基于振动信号和瞬时转速信号的HCCI燃烧相位CA10辨识

    Institute of Scientific and Technical Information of China (English)

    张宏超; 谢辉; 陈韬; 赵华

    2011-01-01

    In order to implement close-loop feedback control of HCCI gasoline engine, an observer model of CA10 is presented based on knock sensor signals and instant engine speed by the mathematical method of Artificial Neural Networks. Based on a great deal of experiment on HCCI engine bench equipped with a fully variable valve actuating system, analysis of and comparison between knock signal, instant speed and CA10 are made, and characteristic parameters are extracted from knock sensor signal and instant speed. Then, an observer of CA10 is built with the characteristic signals of knock sensor and instant speed, which is simple in computation and easy to be implemented on microcontroller. It is shown that the observer is capable of calculating CA10 and the detecting average deviation of combustion phase CA10 is less than 1.7 ° CA.%为了实现基于循环的HCCI燃烧闭环控制,提出了一种基于爆震传感器信号和瞬时转速信号的CA10(缸内燃料燃烧10%累积放热量时的曲轴转角θ10)辨识模型.在装有全可变气门系统的汽油HCCI发动机上,测取HCCI发动机各工况下爆震传感器信号和瞬时转速信号,用时频分析方法从爆震传感器信号及瞬时转速中提取表征振动信号相位信息的特征量和瞬时转速信号特缸最,分析了它们和HCCI燃烧相位θ10之间关系,提出了一种计算简单,以爆震传感器和瞬时转速信号特征量为因变量的CA10辨识模型.分析表明,CA10辨识模型能比较准确地识别HCCI燃烧相位的θ10值,对于HCCI动态过程燃烧相位θ10的预测平均误差小于1.7℃ CA.

  16. Simulating HCCI Blending Octane Number of Primary Reference Fuel with Ethanol

    KAUST Repository

    Singh, Eshan

    2017-03-28

    The blending of ethanol with primary reference fuel (PRF) mixtures comprising n-heptane and iso-octane is known to exhibit a non-linear octane response; however, the underlying chemistry and intermolecular interactions are poorly understood. Well-designed experiments and numerical simulations are required to understand these blending effects and the chemical kinetic phenomenon responsible for them. To this end, HCCI engine experiments were previously performed at four different conditions of intake temperature and engine speed for various PRF/ethanol mixtures. Transfer functions were developed in the HCCI engine to relate PRF mixture composition to autoignition tendency at various compression ratios. The HCCI blending octane number (BON) was determined for mixtures of 2-20 vol % ethanol with PRF70. In the present work, the experimental conditions were considered to perform zero-dimensional HCCI engine simulations with detailed chemical kinetics for ethanol/PRF blends. The simulations used the actual engine geometry and estimated intake valve closure conditions to replicate the experimentally measured start of combustion (SOC) for various PRF mixtures. The simulated HCCI heat release profiles were shown to reproduce the experimentally observed trends, specifically on the effectiveness of ethanol as a low temperature chemistry inhibitor at various concentrations. Detailed analysis of simulated heat release profiles and the evolution of important radical intermediates (e.g., OH and HO) were used to show the effect of ethanol blending on controlling reactivity. A strong coupling between the low temperature oxidation reactions of ethanol and those of n-heptane and iso-octane is shown to be responsible for the observed blending effects of ethanol/PRF mixtures.

  17. Auto-ignition modelling: analysis of the dilution effects by the unburnt gases and of the interactions with turbulence for diesel homogeneous charge compression ignition (HCCI) engines; Modelisation de l'auto-inflammation: analyse des effets de la dilution par les gaz brules et des interactions avec la turbulence dediee aux moteurs Diesel a charge homogene

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, G.

    2005-09-15

    Homogeneous Charge Compression Ignition (HCCI) is an alternative engine combustion process that offers the potential for substantial reductions in both NO{sub x} and particulate matter still providing high Diesel-like efficiencies. Combustion in HCCI mode takes place essentially by auto-ignition. It is mainly controlled by the chemical kinetics. It is therefore necessary to introduce detailed chemistry effects in combustion CFD codes in order to properly model the HCCI combustion process. The objective of this work is to develop an auto-ignition model including detailed chemical kinetics and its interactions with turbulence. Also, a comprehensive study has been performed to analyze the chemical influence of CO and H{sub 2} residual species on auto-ignition, which can be present in the exhaust gases. A new auto-ignition model, TKI-PDF (Tabulated Kinetics for Ignition - with turbulent mixing interactions through a pdf approach) dedicated to RANS 3D engine combustion CFD calculations is proposed. The TKI-PDF model is formulated in order to accommodate the detailed chemical kinetics of auto-ignition coupled with turbulence/chemistry interactions. The complete model development and its validation against experimental results are presented in two parts. The first part of this work describes the detailed chemistry input to the model. The second part is dedicated to the turbulent mixing description. A method based on a progress variable reaction rate tabulation is used. A look-up table for the progress variable reaction rates has been built through constant volume complex chemistry simulations. Instantaneous local reaction rates inside the CFD computational cell are then calculated by linear interpolation inside the look-up table depending on the local thermodynamic conditions. In order to introduce the turbulent mixing effects on auto-ignition, a presumed pdf approach is used. The model has been validated in different levels. First, the detailed kinetic approach was

  18. Effects of Spark Ignition on HCCI Combustion in Gasoline Direct-Injection Engines%火花点火对缸内直喷汽油机HCCI燃烧的影响

    Institute of Scientific and Technical Information of China (English)

    王志; 王建昕; 帅石金; 马青峻

    2005-01-01

    实现汽油机均质混合气压燃(HCCI)的难点是着火控制.在缸内直喷汽油机上实现了HCCI燃烧,研究了火花点火对HCCI燃烧特性的影响.结果表明,HCCI燃烧方式较火花点火(SI)火焰传播燃烧方式放热速率快,热效率高,NOx大幅度降低.在HCCI临界状态时,火花点火有助于提高燃烧稳定性,抑制失火和爆燃,降低循环波动;当火花点火时缸内温度远超过临界着火温度时,火花点火对HCCI燃烧影响不大.火花点火在SI/HCCI燃烧模式切换工况时,能提高瞬态过渡平顺性.

  19. 催化燃烧对均质压燃发动机排放影响的数值模拟%Simulation of Influences of Catalytic Combustion on the Emissions of HCCI Engine

    Institute of Scientific and Technical Information of China (English)

    曾文; 解茂昭; 贾明

    2007-01-01

    通过耦合DETCHEM软件包及CHEMKIN软件包中的SENKIN模块,对活塞顶涂有催化剂的均质压燃(HCCI)发动机的燃烧过程进行了数值计算,建立了多区模型.利用此模型分析了催化燃烧对HCCI发动机缸内温度、热释放速率以及未燃碳氢化合物(UHC)、氮氧化合物(NOx)、一氧化碳(CO)排放的影响,结果表明催化燃烧能降低UHC、CO的排放,但NOx的排放会有所升高,对不弼催化剂及混合催化剂对HCCI发动机缸内温度、热释放速率以及UHC、NOx、CO排放的影响进行了探索,结果表明,和金属铂相比,以铑作催化剂时UHC的排放降低,但NOx、CO排放会有所升高;采用50%Pt-50%Rh的混合催化剂时,UHC、NOx的排放介于100%Pt与100%Rh之间,但CO的排放却比采用100%Pt与100%Rh时都要低.

  20. Chemical Kinetic Models for Advanced Engine Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Pitz, William J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mehl, Marco [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Westbrook, Charles K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-22

    The objectives for this project are as follows: Develop detailed chemical kinetic models for fuel components used in surrogate fuels for compression ignition (CI), homogeneous charge compression ignition (HCCI) and reactivity-controlled compression-ignition (RCCI) engines; and Combine component models into surrogate fuel models to represent real transportation fuels. Use them to model low-temperature combustion strategies in HCCI, RCCI, and CI engines that lead to low emissions and high efficiency.

  1. Super SI燃烧方式试验研究%Super SI Combustion Mode

    Institute of Scientific and Technical Information of China (English)

    沈义涛; 吕世亮; 尹琪; 杨嘉林; 高卫民

    2011-01-01

    The super spark ignition (Super SI) combustion mode, which was the ignition combustion of lean mixture at the temperature of close spontaneous combustion, was researched and its combustion characteristic and feasibility were analyzed.The results indicate that the increase of intake temperature can reduce the cyclic variation of Pmi obviously, shorten the combustion duration and extend the lean limit of SI combustion under the condition of lean mixture. Accordingly, Super SI combustion has the advantages of high thermal efficiency and controllable combustion process.%研究了Super Spark Ignition(Super SI)燃烧方式,即稀薄混合气在近自燃温度状态下点燃燃烧,分析了这种燃烧方式的可行性和燃烧特性.研究结果表明,混合气稀薄时提高发动机的进气温度可显著降低平均指示压力(pmi)的循环波动,缩短燃烧持续期,拓展点燃燃烧的稀薄极限;Super SI燃烧方式具有热效率高、燃烧过程可控的优点.

  2. Enabling HCCI modeling: The RIOT/CMCS Web Service for Automatic Reaction Mechanism Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Oluwole, O; Pitz, W J; Schuchardt, K; Rahn, L A; Green, Jr., W H; Leahy, D; Pancerella, C; Sj?berg, M; Dec, J

    2005-12-12

    New approaches are being developed to facilitate multidisciplinary collaborative research of Homogeneous Charge Compression Ignition (HCCI) combustion processes. In this paper, collaborative sharing of the Range Identification and Optimization Toolkit (RIOT) and related data and models is discussed. RIOT is a developmental approach to reduce the computational complexity of detailed chemical kinetic mechanisms, enabling their use in modeling kinetically-controlled combustion applications such as HCCI. These approaches are being developed and piloted as a part of the Collaboratory for Multiscale Chemical Sciences (CMCS) project. The capabilities of the RIOT code are shared through a portlet in the CMCS portal that allows easy specification and processing of RIOT inputs, remote execution of RIOT, tracking of data pedigree and translation of RIOT outputs (such as the reduced model) to a table view and to the commonly-used CHEMKIN mechanism format. The reduced model is thus immediately ready to be used for more efficient simulation of the chemically reacting system of interest. This effort is motivated by the need to improve computational efficiency in modeling HCCI systems. Preliminary use of the web service to obtain reduced models for this application has yielded computational speedup factors of up to 20 as presented in this paper.

  3. Development of HCCI Engines for Dimethyl Ether

    DEFF Research Database (Denmark)

    Hansen, Kim Rene; Pedersen, Troels Dyhr; Schramm, Jesper

    This report has been prepared for the Danish Energy Agency. It summarizes the results of the project entitled: “Development of HCCI engines for DME”. The project has been financed by “EFP 06”. The chapters about theoretical and experimental studies have been written using the language...

  4. Combustion

    CERN Document Server

    Glassman, Irvin

    1987-01-01

    Combustion, Second Edition focuses on the underlying principles of combustion and covers topics ranging from chemical thermodynamics and flame temperatures to chemical kinetics, detonation, ignition, and oxidation characteristics of fuels. Diffusion flames, flame phenomena in premixed combustible gases, and combustion of nonvolatile fuels are also discussed. This book consists of nine chapters and begins by introducing the reader to heats of reaction and formation, free energy and the equilibrium constants, and flame temperature calculations. The next chapter explores the rates of reactio

  5. Combustion in Homogeneous Charge Compression Ignition Engines: Experiments and Detailed Chemical Kinetic Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Flowers, D L

    2002-06-07

    Homogeneous charge compression ignition (HCCI) engines are being considered as an alternative to diesel engines. The HCCI concept involves premixing fuel and air prior to induction into the cylinder (as is done in current spark-ignition engine) then igniting the fuel-air mixture through the compression process (as is done in current diesel engines). The combustion occurring in an HCCI engine is fundamentally different from a spark-ignition or Diesel engine in that the heat release occurs as a global autoignition process, as opposed to the turbulent flame propagation or mixing controlled combustion used in current engines. The advantage of this global autoignition is that the temperatures within the cylinder are uniformly low, yielding very low emissions of oxides of nitrogen (NO{sub x}, the chief precursors to photochemical smog). The inherent features of HCCI combustion allows for design of engines with efficiency comparable to, or potentially higher than, diesel engines. While HCCI engines have great potential, several technical barriers exist which currently prevent widespread commercialization of this technology. The most significant challenge is that the combustion timing cannot be controlled by typical in-cylinder means. Means of controlling combustion have been demonstrated, but a robust control methodology that is applicable to the entire range of operation has yet to be developed. This research focuses on understanding basic characteristics of controlling and operating HCCI engines. Experiments and detailed chemical kinetic simulations have been applied to the characterize some of the fundamental operational and design characteristics of HCCI engines. Experiments have been conducted on single and multi-cylinder engines to investigate general features of how combustion timing affects the performance and emissions of HCCI engines. Single-zone modeling has been used to characterize and compare the implementation of different control strategies. Multi

  6. Investigation of JP-8 Autoignition Under Vitiated Combustion Conditions

    Science.gov (United States)

    2011-01-01

    combustion engines and HCCI systems rather than low pressure combustion devices that are of interest in the current study. This data provides insight...2011 Directed by: Professor Gregory Jackson, Chair Department of Mechanical Engineering Limited data on jet fuel ignition and oxidation at...Fuller 2011 ii Acknowledgements This research has been supported and funded by Combustion Science and Engineering , Inc. through the following

  7. Multi-dimensional modeling of the application of catalytic combustion to homogeneous charge compression ignition engine

    Science.gov (United States)

    Zeng, Wen; Xie, Maozhao

    2006-12-01

    The detailed surface reaction mechanism of methane on rhodium catalyst was analyzed. Comparisons between numerical simulation and experiments showed a basic agreement. The combustion process of homogeneous charge compression ignition (HCCI) engine whose piston surface has been coated with catalyst (rhodium and platinum) was numerically investigated. A multi-dimensional model with detailed chemical kinetics was built. The effects of catalytic combustion on the ignition timing, the temperature and CO concentration fields, and HC, CO and NOx emissions of the HCCI engine were discussed. The results showed the ignition timing of the HCCI engine was advanced and the emissions of HC and CO were decreased by the catalysis.

  8. HCCI Intelligent Rapid Modeling by Artificial Neural Network and Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    AbdoulAhad Validi

    2012-01-01

    Full Text Available A Dynamic model of Homogeneous Charge Compression Ignition (HCCI, based on chemical kinetics principles and artificial intelligence, is developed. The model can rapidly predict the combustion probability, thermochemistry properties, and exact timing of the Start of Combustion (SOC. A realization function is developed on the basis of the Sandia National Laboratory chemical kinetics model, and GRI3.0 methane chemical mechanism. The inlet conditions are optimized by Genetic Algorithm (GA, so that combustion initiates and SOC timing posits in the desired crank angle. The best SOC timing to achieve higher performance and efficiency in HCCI engines is between 5 and 15 degrees crank angle (CAD after top dead center (TDC. To achieve this SOC timing, in the first case, the inlet temperature and equivalence ratio are optimized simultaneously and in the second case, compression ratio is optimized by GA. The model’s results are validated with previous works. The SOC timing can be predicted in less than 0.01 second and the CPU time savings are encouraging. This model can successfully be used for real engine control applications.

  9. Progress in analytical methods to predict and control azimuthal combustion instability modes in annular chambers

    Science.gov (United States)

    Bauerheim, M.; Nicoud, F.; Poinsot, T.

    2016-02-01

    Longitudinal low-frequency thermoacoustic unstable modes in combustion chambers have been intensively studied experimentally, numerically, and theoretically, leading to significant progress in both understanding and controlling these acoustic modes. However, modern annular gas turbines may also exhibit azimuthal modes, which are much less studied and feature specific mode structures and dynamic behaviors, leading to more complex situations. Moreover, dealing with 10-20 burners mounted in the same chamber limits the use of high fidelity simulations or annular experiments to investigate these modes because of their complexity and costs. Consequently, for such circumferential acoustic modes, theoretical tools have been developed to uncover underlying phenomena controlling their stability, nature, and dynamics. This review presents recent progress in this field. First, Galerkin and network models are described with their pros and cons in both the temporal and frequency framework. Then, key features of such acoustic modes are unveiled, focusing on their specificities such as symmetry breaking, non-linear modal coupling, forcing by turbulence. Finally, recent works on uncertainty quantifications, guided by theoretical studies and applied to annular combustors, are presented. The objective is to provide a global view of theoretical research on azimuthal modes to highlight their complexities and potential.

  10. Using biofuel tracers to study alternative combustion regimes

    Science.gov (United States)

    Mack, J. H.; Flowers, D. L.; Buchholz, B. A.; Dibble, R. W.

    2007-06-01

    Interest in the use of alternative fuels and engines is increasing as the price of petroleum climbs. The inherently higher efficiency of Diesel engines has led to increased adoption of Diesels in Europe, capturing approximately 40% of the new passenger car market. Unfortunately, lower CO2 emissions are countered with higher nitrogen oxides (NOx) and particulate matter (PM) emissions and higher noise. Adding oxygenated compounds to the fuel helps reduce PM emissions. However, relying on fuel alone to reduce PM is unrealistic due to economic constraints and difficult due to the emerging PM standards. Keeping peak combustion temperature below 1700 K inhibits NOx formation. Altering the combustion regime to burn at temperatures below the NOx threshold and accept a wide variety of fuels seems like a promising alternative for future engines. Homogeneous charge compression ignition (HCCI) is a possible solution. Fuel and air are well mixed prior to intake into a cylinder (homogeneous charge) and ignition occurs by compression of the fuel-air mixture by the piston. HCCI is rapid and relatively cool, producing little NOx and PM. Unfortunately, it is hard to control since HCCI is initiated by temperature and pressure instead of a spark or direct fuel injection. We investigate biofuel HCCI combustion, and use intrinsically labeled biofuels as tracers of HCCI combustion. Data from tracer experiments are used to improve our combustion modeling.

  11. Effective identification of the three particle modes generated during pulverized coal combustion

    Institute of Scientific and Technical Information of China (English)

    YU DunXi; XU MingHou; YAO Hong; LIU XiaoWei; ZHOU Ke

    2008-01-01

    Based on the mass fraction size distribution of aluminum (AI), an improved method for effectively identifying the modes of particulate matter from pulverized coal combustion is proposed in this study. It is found that the particle size distributions of coal-derived particulate matter actually have three modes, rather than just mere two. The ultrafine mode is mainly generated through the vaporization and condensation processes. The coarse mode is primarily formed by the coalescence of molten minerals, while the newly-found central mode is attributed to the heterogeneous condensation or adsorption of vaporized species on fine residual ash particles. The detailed investigation of the mass fraction size distribution of sulfur (S) further demonstrates the rationality and effectiveness of the mass fraction size distribution of the AI in identifying three particle modes. The results show that not only can the number of particle modes be identified in the mass fraction size distributions of the AI but also can their size boundaries be more accurately defined. This method provides new insights in elucidating particle formation mechanisms and their physico-chemical characteristics.

  12. Enhanced RAMAC performance in subdetonative propulsion mode with semi-combustible projectile

    Energy Technology Data Exchange (ETDEWEB)

    Legendre, J.F.; Giraud, M. [French-German Res. Inst., Saint-Louis (France)

    2000-11-01

    Investigations are carried out at ISL to determine the experimental conditions required to accelerate a projectile in the mass range from 1.5 to 2 kg up to a muzzle velocity of 3 km/s while keeping the maximum acceleration below 40,000 g. Therefore, two smooth-bore ram-accelerators denoted RAMAC 30-II and RAMAC 90, in caliber 30 and 90 mm respectively, are being operated in the thermally choked propulsion mode. Different material configurations for the projectile afterbody have been investigated, while keeping an aluminum nose cone. Besides afterbodies made of aluminum or magnesium alloy only, a third configuration is presented relying on a short magnesium part fitted to the base of an aluminum afterbody. This configuration denoted as ''semi-combustible'' is designed so that magnesium particles are steadily injected and burnt-out within the combustion zone at the base, therefore providing an additional heat release and consequently a significantly greater forward thrust. Experimental results achieved in both 30 and 90 mm along a 300-caliber-long ram-section and using up to three different gaseous mixtures are presented. To date, for a given semi-combustible projectile and an injection velocity into the ram-section of 1380 m/s, a maximum muzzle velocity of 2380 m/s has been achieved in RAMAC 30-II and 2180 m/s in RAMAC 90, the initial projectile mass being 69 g and 1608 g respectively. (orig.)

  13. A two conserved scalar model for HCCI and PPCI engine applications

    Science.gov (United States)

    Hamosfakidis, Vasileios

    There is a strong demand for a versatile computational model in the design of modern engines such as homogeneous charge compression ignition (HCCI) and partially premixed compression ignition (PPCI) engines. A robust model is required to describe accurately both the chemistry and turbulent mixing processes in the reacting flow. Although the existing computational fluid dynamics (CFD) codes coupled with detailed kinetics models may reproduce some realistic results, the excessive computational cost prevents them to be applicable as engineering tools. The present study aims at developing a new modeling approach that can describe the combustion process with high fidelity and computational efficiency. In this study, a two-conserved scalar approach is proposed to model HCCI and PPCI combustion. The first conserved scalar, the mixture fraction Z, is introduced to capture the inhomogeneities in the fuel-air mixture, and the second conserved scalar, the initial EGR fraction J, is introduced to capture the inhomogeneities in the fresh mixture-EGR charge. The main benefits of this approach are the reduction of dimensionality and the compactness of the domain in the conserved scalar plane, and the capability to use different resolutions for the chemistry and the fluid mechanics calculation. To solve the flow in the conserved scalar plane, two algorithms are proposed. First, the flamelet (zone) creation strategy is introduced to discretize the conserved scalar space based on its mass distribution and reactivity. The second part is the regeneration procedure which accounts for the nonlinear effect of EGR on reaction rates. Test results from the two-conserved scalar approach are compared to those obtained by direct calculation, and it is demonstrated that the regeneration process in the present approach can properly account for the nonlinear effects arising from chemical reactions, as an improvement over the representative interactive flamelet (RIF) approach. The two conserved

  14. Formation mechanism of bimetal composite layer between LCS and HCCI

    Directory of Open Access Journals (Sweden)

    Yong-chang Zhu

    2016-11-01

    Full Text Available A low carbon steel (LCS/high chromium white cast iron (HCCI bimetal wear plate about 20 mm in thickness was prepared by liquid-liquid bimetal composite casting technology to substitute for the welding wear plate. A clear and distinguishable composite layer between the LCS and the HCCI was detected with SEM, and the composition and phase were analyzed through EDS and XRD. The composite layer was composed of three sublayers from the LCS to the HCCI: pearlite transition layer, composite layer, and HCCI transition layer. The Vickers hardness from the pearlite transition layer to the HCCI transition layer was 360 HV to 855 HV. The austenite grows as dendrites between the composite layer and the HCCI transition layer under constitutional undercooling. A large amount of C and Cr, and a small amount of Si and Mn dissolve in the matrix. Granular Cr7C3 is uniformly distributed. Due to the solute redistribution at the solid-liquid interface, the primary austenite grows from planar to cellular and finally to the distinct dendrite crystals. The dendrite crystals have an obvious growth direction perpendicular to the composite layer.

  15. Simulations of Multi Combustion Modes Hydrogen Engines for Heavy Duty Trucks

    Directory of Open Access Journals (Sweden)

    Alberto A. Boretti

    2012-01-01

    Full Text Available The paper presents the numerical study of a diesel direct injection heavy duty truck engine converted to hydrogen. The engine has a power turbine connected through a clutch and a continuously variable transmission to the crankshaft. The power turbine may be disconnected and by-passed when it is inefficient or inconvenient to use. The conversion is obtained by replacing the Diesel injector with a hydrogen injector and the glow plug with a jet ignition device. The hydrogen engine operates different modes of combustion depending on the relative phasing of the main injection and the jet ignition. The engine generally operates mostly in Diesel-like mode, with the most part of the main injection following the suitable creation in cylinder conditions by jet ignition. For medium-low loads, better efficienciy is obtained with the gasoline-like mode jet igniting the premixed homogeneous mixture at top dead centre. It’s permitted at higher loads or at very low loads for the excessive peak pressure or the mixture too lean to burn rapidly. The hydrogen engine has better efficiency than Diesel outputs and fuel conversion. Thanks to the larger rate of heat release, it has the opportunity to run closer to stoichiometry and the multi mode capabilities. The critical area for this engine development is found in the design of a hydrogen injector delivering the amount of fuel needed to the large volume cylinder within a Diesel-like injection time.

  16. A predication model for combustion modes of the scramjet-powered aerospace vehicle based on the nonlinear features of the isolator flow field

    Science.gov (United States)

    Yang, Qingchun; Wang, Hongxin; Chetehouna, Khaled; Gascoin, Nicolas

    2017-01-01

    The supersonic combustion ramjet (scramjet) engine remains the most promising airbreathing engine cycle for hypersonic flight, particularly the high-performance dual-mode scramjet in the range of flight Mach number from 4 to 7, because it can operates under different combustion modes. Isolator is a very key component of the dual-mode scramjet engine. In this paper, nonlinear characteristics of combustion mode transition is theoretically analyzed. The discontinuous sudden changes of static pressure and Mach number are obtained as the mode transition occurs, which emphasizing the importance of predication and control of combustion modes. In this paper, a predication model of different combustion modes is developed based on these these nonlinear features in the isolator flow field. it can provide a valuable reference for control system design of the scramjet-powered aerospace vehicle.

  17. Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber

    KAUST Repository

    Shi, Xian

    2017-01-05

    Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber are numerically investigated using an 1-D unsteady, shock-capturing, compressible and reacting flow solver. Different combinations of reaction front propagation and end-gas combustion modes are observed, i.e., 1) deflagration without end-gas combustion, 2) deflagration to end-gas autoignition, 3) deflagration to end-gas detonation, 4) developing or developed detonation, occurring in the sequence of increasing initial temperatures. Effects of ignition location and chamber size are evaluated: the asymmetric ignition is found to promote the reactivity of unburnt mixture compared to ignitions at center/wall, due to additional heating from asymmetric pressure waves. End-gas combustion occurs earlier in smaller chambers, where end-gas temperature rise due to compression heating from the deflagration is faster. According to the ξ−ε regime diagram based on Zeldovich theory, modes of reaction front propagation are primarily determined by reactivity gradients introduced by initial ignition, while modes of end-gas combustion are influenced by the total amount of unburnt mixture at the time when autoignition occurs. A transient reactivity gradient method is provided and able to capture the occurrence of detonation.

  18. Miniature Internal Combustion Engine-Generator for High Energy Density Portable Power

    Science.gov (United States)

    2008-12-01

    very effective at maintaining a constant voltage and stroke as the HCCI combustion pressure varies during engine warmup. The current is modulated by the...Comparison of Measured and Predicted Two- Stroke Engine Power Output for Jet-A and Propane 5 The exhaust emissions of the 300 W MICE generator with HCCI ...1 Two-Stroke Engine Double- Helix Spring Linear Alternator Magnet Pole Permanent Magnet Alternator Coil Spring Casing Coil Standoff Double-Helix

  19. Large Eddy Simulation of Turbulent Combustion

    Science.gov (United States)

    2006-03-15

    Application to an HCCI Engine . Proceedings of the 4th Joint Meeting of the U.S. Sections of the Combustion Institute, 2005. [34] K. Fieweger...LARGE EDDY SIMULATION OF TURBULENT COMBUSTION Principle Investigator: Heinz Pitsch Flow Physics and Computation Department of Mechanical Engineering ...burners and engines found in modern, industrially relevant equipment. In the course of this transition of LES from a scientifically interesting method

  20. A numerical study on combustion process in a small compression ignition engine run dual-fuel mode (diesel-biogas)

    Science.gov (United States)

    Ambarita, H.; Widodo, T. I.; Nasution, D. M.

    2017-01-01

    In order to reduce the consumption of fossil fuel of a compression ignition (CI) engines which is usually used in transportation and heavy machineries, it can be operated in dual-fuel mode (diesel-biogas). However, the literature reviews show that the thermal efficiency is lower due to incomplete combustion process. In order to increase the efficiency, the combustion process in the combustion chamber need to be explored. Here, a commercial CFD code is used to explore the combustion process of a small CI engine run on dual fuel mode (diesel-biogas). The turbulent governing equations are solved based on finite volume method. A simulation of compression and expansions strokes at an engine speed and load of 1000 rpm and 2500W, respectively has been carried out. The pressure and temperature distributions and streamlines are plotted. The simulation results show that at engine power of 732.27 Watt the thermal efficiency is 9.05%. The experiment and simulation results show a good agreement. The method developed in this study can be used to investigate the combustion process of CI engine run on dual-fuel mode.

  1. Homogeneous Charge Compression Ignition Combustion of Dimethyl Ether

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr

    mechanism greatly reduces both. Reaction paths for methanol and methane were included amongst the elementary reactions, since these two fuels are commonly used to control the radical behavior in the initial phase of combustion and hence the combustion phasing of the fuel in an engine, as well as enabling...... an increase in engine power. The use of methanol for combustion phasing control was tested successfully in a large diesel engine with common rail, in which the piston bowls were widened to give a compression ratio of 14.5. This compression ratio still allows DI CI operation with DME, but requires...... a substantial combustion delay in HCCI operation with DME to achieve post TDC combustion. By adding methanol to the inlet port during HCCI combustion of DME, the engine reached 50 percent of its full DI CI load capability without engine knock at 1000 rpm and somewhat less at 1800 rpm. The engine also had EGR...

  2. High-Speed Visualisation of Combustion in Modern Gasoline Engines

    Science.gov (United States)

    Sauter, W.; Nauwerck, A.; Han, K.-M.; Pfeil, J.; Velji, A.; Spicher, U.

    2006-07-01

    Today research and development in the field of gasoline engines have to face a double challenge: on the one hand, fuel consumption has to be reduced, while on the other hand, ever more stringent emission standards have to be fulfilled. The development of engines with its complexity of in-cylinder processes requires modern development tools to exploit the full potential in order to reduce fuel consumption. Especially optical, non-intrusive measurement techniques will help to get a better understanding of the processes. With the presented high-speed visualisation system the electromagnetic radiation from combustion in the UV range is collected by an endoscope and transmitted to a visualisation system by 10, 000 optical fibres. The signal is projected to 1, 920 photomultipliers, which convert the optical into electric signals with a maximum temporal resolution of 200 kHz. This paper shows the systematic application of flame diagnostics in modern combustion systems. For this purpose, a single-cylinder SI engine has been modified for a spray guided combustion strategy as well as for HCCI. The characteristics of flame propagation in both combustion modes were recorded and correlated with thermodynamic analyses. In case of the spray guided GDI engine, high pressure fuel injection was applied and evaluated.

  3. Combustion characteristics of diesel engine using producer gas and blends of Jatropha methyl ester with diesel in mixed fuel mode

    Directory of Open Access Journals (Sweden)

    Hifjur Raheman

    2014-12-01

    Full Text Available An experimental investigation was performed to study the combustion characteristics of diesel engine fuelled with producer gas-biodiesel in dual fuel mode. Three different fuel blends of Jatropha methyl ester with high speed diesel (HSD (B10, B20 and B100 were used with producer gas obtained from the gasification of briquettes made from de-oiled Jatropha seed cake. The increments in load on the engine increased the brake thermal efficiency, exhaust gas temperature and lowered the brake specific energy consumption. The ignition delays in dual-fuel mode of operation for both the fuels were longer than for single-fuel mode of operation. Combustion pressure and heat release rate (HRR patterns at different engine loads were found to be similar for biodiesel and HSD. In dual-fuel mode, the peak pressure and HRR for producer gas–biodiesel dual-fuel were slightly lower than those of producer gas–diesel combustion at full load condition. Significantly lower NOx emissions were obtained under the dual fuel mode of operation for both pilot fuels compared to the single-fuel mode especially HSD under all test conditions.

  4. Optimization of a Reduced Chemical Kinetic Model for HCCI Engine Simulations by Micro-Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A reduced chemical kinetic model (44 species and 72 reactions) for the homogeneous charge compression ignition (HCCI) combustion of n-heptane was optimized to improve its autoignition predictions under different engine operating conditions. The seven kinetic parameters of the optimized model were determined by using the combination of a micro-genetic algorithm optimization methodology and the SENKIN program of CHEMKIN chemical kinetics software package. The optimization was performed within the range of equivalence ratios 0.2-1.2, initial temperature 310-375 K and initial pressure 0.1-0.3 MPa. The engine simulations show that the optimized model agrees better with the detailed chemical kinetic model (544 species and 2 446 reactions) than the original model does.

  5. Effects of boron addition on the formation of MoSi{sub 2} by combustion synthesis mode

    Energy Technology Data Exchange (ETDEWEB)

    Feng Peizhong, E-mail: fengroad@163.co [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China) and School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116 (China); Wu Jie [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Islam, S.H. [Department of Metallurgical Engineering, NED University of Engineering and Technology, University Road, Karachi 75270 (Pakistan); Liu Weisheng; Niu Jinan; Wang Xiaohong; Qiang Yinghuai [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China)

    2010-04-02

    The combustion synthesis behavior of Mo-Si-B powder was investigated. Test specimens with nominal compositions including MoSi{sub 2}, Mo(Si{sub 0.975}B{sub 0.025}){sub 2}, Mo(Si{sub 0.95}B{sub 0.05}){sub 2}, Mo(Si{sub 0.925}B{sub 0.075}){sub 2} and Mo(Si{sub 0.9}B{sub 0.1}){sub 2} were employed. The combustion mode, propagation velocity of combustion wave, combustion temperature and combustion product structure were studied. The results showed that the combustion wave propagated along a spiral trajectory till reaching the bottom of the compacts. The combustion temperature was increased by the addition of boron, to as high as 1922 K in the case of the Mo(Si{sub 0.95}B{sub 0.05}){sub 2} sample. However, the flame-front propagation velocity decreased as a result of the addition of boron. The X-ray diffraction results showed that the combustion products of the Mo(Si{sub 0.975}B{sub 0.025}){sub 2} and Mo(Si{sub 0.9}B{sub 0.1}){sub 2} samples were composed of MoSi{sub 2} with minor MoB. Those of the Mo(Si{sub 0.95}B{sub 0.05}){sub 2} and Mo(Si{sub 0.925}B{sub 0.075}){sub 2} samples were composed of MoSi{sub 2} with minor MoB and MoB{sub 2}. And traces of Mo{sub 2}B{sub 5} were identified in the Mo(Si{sub 0.95}B{sub 0.05}){sub 2} sample.

  6. An experiment study of homogeneous charge compression ignition combustion and emission in a gasoline engine

    Directory of Open Access Journals (Sweden)

    Zhang Jianyong

    2014-01-01

    Full Text Available Homogenous charge compression ignition (HCCI technology has exhibited high potential to reduce fuel consumption and NOx emissions over normal spark ignition engines significantly. Optimized kinetic process (OKP technology is implemented to realize HCCI combustion in a port fuel injection gasoline engine. The combustion and emission characteristics are investigated with variation of intake air temperature, exhaust gas recirculation (EGR rate and intake air pressure. The results show that intake air temperature has great influence on HCCI combustion characteristic. Increased intake air temperature results in advance combustion phase, shorten combustion duration, and lower indicated mean effective pressure (IMEP. Increased EGR rate retards combustion start phase and prolongs combustion duration, while maximum pressure rising rate and NOx emission are reduced with increase of EGR rate. In the condition with constant fuel flow quantity, increased air pressure leads to retarded combustion phase and lower pressure rising rate, which will reduce the engine knocking tendency. In the condition with constant air fuel ratio condition, fuel injection quantity increases as intake air pressure increases, which lead to high heat release rate and high emission level. The optimal intake air temperature varies in different operating area, which can be tuned from ambient temperature to 220℃ by heat management system. The combination of EGR and air boost technology could expand operating area of HCCI engine, which improve indicated mean effective pressure from maximum 510kPa to 720kPa.

  7. Numerical exploration of mixing and combustion in a dual-mode combustor with backward-facing steps

    Science.gov (United States)

    Huang, Wei; Li, Lang-quan; Yan, Li; Liao, Lei

    2016-10-01

    Dual-mode scramjet combustor is the crucial component for the combined cycle engine of space mission vehicles. The Reynolds Averaged Navier-Stokes (RANS) equations, Spalart-Allmaras turbulence model and the finite-rate reaction model have been utilized to investigate the mixing and combustion in a dual-mode combustor with backward-facing steps, and the species distributions and the Mach number profile of a turbulent diffusion combustion problem have been employed to validate the numerical approach. Moreover, the influences of the injection strategy and the fuel equivalence ratio arrangement on its mixing and combustion flow fields have been explored. The obtained results show that the vertical injection is beneficial for mode transition, and an obvious high pressure region is generated with the vertical injection strategy. Accordingly, its mass-weighted average Mach number drops more sharply. The lower total equivalence ratio is beneficial for the mixing augmentation, as well the smaller fuel equivalence ratio discrepancy. However, the larger total equivalence ratio is beneficial for the mode transition.

  8. Intermediate temperature heat release in an HCCI engine fueled by ethanol/n-heptane mixtures: An experimental and modeling study

    KAUST Repository

    Vuilleumier, David

    2014-03-01

    This study examines intermediate temperature heat release (ITHR) in homogeneous charge compression ignition (HCCI) engines using blends of ethanol and n-heptane. Experiments were performed over the range of 0-50% n-heptane liquid volume fractions, at equivalence ratios 0.4 and 0.5, and intake pressures from 1.4bar to 2.2bar. ITHR was induced in the mixtures containing predominantly ethanol through the addition of small amounts of n-heptane. After a critical threshold, additional n-heptane content yielded low temperature heat release (LTHR). A method for quantifying the amount of heat released during ITHR was developed by examining the second derivative of heat release, and this method was then used to identify trends in the engine data. The combustion process inside the engine was modeled using a single-zone HCCI model, and good qualitative agreement of pre-ignition pressure rise and heat release rate was found between experimental and modeling results using a detailed n-heptane/ethanol chemical kinetic model. The simulation results were used to identify the dominant reaction pathways contributing to ITHR, as well as to verify the chemical basis behind the quantification of the amount of ITHR in the experimental analysis. The dominant reaction pathways contributing to ITHR were found to be H-atom abstraction from n-heptane by OH and the addition of fuel radicals to O2. © 2013 The Combustion Institute.

  9. Effects of compression ratio on the combustion characteristics of a homogeneous charge compression ignition engine

    Institute of Scientific and Technical Information of China (English)

    SONG Ruizhi; HU Tiegang; ZHOU Longbao; LIU Shenghua; LI Wei

    2007-01-01

    The effects of homogeneous charge compression ignition (HCCI) engine compression ratio on its combustion characteristics were studied experimentally on a modified TY1100 single cylinder engine fueled with dimethyl ether.The results show that dimethyl ether (DME) HCCI engine can work stably and can realize zero nitrogen oxides (NOx)emission and smokeless combustion under the compression ratio of both 10.7 and 14.The combustion process has obvious two stage combustion characteristics at ε = 10.7(εrefers to compression ratio),and the combustion beginning point is decided by the compression temperature,which varies very little with the engine load;the combustion beginning point is closely related to the engine load (concentration of mixture) with the increase in the compression temperature,and it moves forward versus crank angle with the increase in the engine load at ε = 14;the combustion durations are shortened with the increase in the engine load under both compression ratios.

  10. The influence of beam energy, mode and focal length on the control of laser ignition in an internal combustion engine

    Science.gov (United States)

    Mullett, J. D.; Dodd, R.; Williams, C. J.; Triantos, G.; Dearden, G.; Shenton, A. T.; Watkins, K. G.; Carroll, S. D.; Scarisbrick, A. D.; Keen, S.

    2007-08-01

    This work involves a study on laser ignition (LI) in an internal combustion (IC) engine and investigates the effects on control of engine combustion performance and stability of varying specific laser parameters (beam energy, beam quality, minimum beam waist size, focal point volume and focal length). A Q-switched Nd : YAG laser operating at the fundamental wavelength 1064 nm was successfully used to ignite homogeneous stoichiometric gasoline and air mixtures in one cylinder of a 1.6 litre IC test engine, where the remaining three cylinders used conventional electrical spark ignition (SI). A direct comparison between LI and conventional SI is presented in terms of changes in coefficient of variability in indicated mean effective pressure (COVIMEP) and the variance in the peak cylinder pressure position (VarPPP). The laser was individually operated in three different modes by changing the diameter of the cavity aperture, where the results show that for specific parameters, LI performed better than SI in terms of combustion performance and stability. Minimum ignition energies for misfire free combustion ranging from 4 to 28 mJ were obtained for various optical and laser configurations and were compared with the equivalent minimum optical breakdown energies in air.

  11. Multi-dimensional Modeling of the Application of Catalytic Combustion to Homogeneous Charge Compression Ignition Engine

    Institute of Scientific and Technical Information of China (English)

    Wen Zeng; MaoZhao Xie

    2006-01-01

    The detailed surface reaction mechanism of methane on rhodium catalyst was analyzed.Comparisons between numerical simulation and experiments showed a basic agreement.The combustion process of homogeneous charge compression ignition (HCCI) engine whose piston surface has been coated with catalyst (rhodium and platinum) was numerically investigated.A multi-dimensional model with detailed chemical kinetics was built.The effects of catalytic combustion on the ignition timing,the temperature and CO concentration fields,and HC,CO and NOx emissions of the HCCI engine were discussed.The results showed the ignition timing of the HCCI engine was advanced and the emissions of HC and CO were decreased by the catalysis.

  12. 缸内直喷汽油机HCCI燃烧对压缩比和辛烷值的适应性研究%Dependence of HCCI Combustion on Compression Ratio and Fuel Property in a Gasoline Direct Injection Engine

    Institute of Scientific and Technical Information of China (English)

    王志; 杨俊伟; 张志福; 葛强强; 田国弘; 王建昕

    2007-01-01

    在缸内直喷汽油机(GDI)上采用多次燃油喷射和可变配气技术来控制缸内混合气形成和燃烧,实现了SI/HCCI复合燃烧方式.研究了不同压缩比和辛烷值对均质混合气压燃(HCCI)燃烧排放特性的影响.结果表明,汽油HCCI燃烧呈现单阶段燃烧燃料特性,HCCI着火发生在上止点附近时油耗低.低压缩比下,HCCI燃烧可以在较浓空燃比下工作,NOx排放较高.高辛烷值燃料HCCI燃烧可运行的负荷范围窄.汽油HCCI发动机在偏高压缩比条件下燃用偏低辛烷值汽油可以获得较好的经济性和排放性能.

  13. Simulation of Aviation Kerosene Combustion in Dual-mode Scramjet Combustor

    Institute of Scientific and Technical Information of China (English)

    LIU Ou-zi; ZOU Jian-feng; CAI Yuan-hu; HU Yu-li

    2009-01-01

    Supersonic combustion of aviation kerosene is investigated under the flight conditions of Mach number 5 and fuel-air equivalence ratio 0.551. The trajectories of the fuel droplets and the heat/mass transfer between them are simulated by means of discrete phase model (DPM). The k-ω model is chosen for turbulence closure and the non-premixed probability density function (PDF) approach is used to calculate the turbulence-chemistry interaction. The calculated wall static pressure and the total pressure loss coefficient are very close to the experiment results. The strut and cavity devices significantly increase the combustion efficiency.

  14. MTU series 1600 HCCI engine with extremely low exhaust emissions over the entire engine map; HCCI-Motor der MTU Baureihe 1600 mit extrem niedrigen Abgasemissionen im gesamten Motorkennfeld

    Energy Technology Data Exchange (ETDEWEB)

    Teetz, Christoph; Bergmann, Dirk; Sauer, Christina; Schneemann, Arne [MTU, Friedrichshafen (Germany); Eichmeier, Johannes; Spicher, Ulrich [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). IFKM

    2012-11-01

    The main challenge when developing off-highway engines is to keep emissions within the limits to apply in the future while maintaining low fuel consumption and low CO{sub 2} output. In the USA in particular, diesel engines in the 130 - 560 kW power range are to be subject from 2014 to EPA Tier 4 legislation, which imposes limits of 0.4 g/kWh for NO{sub x} and 0.02 g/kWh for particulate matter. Diesel units can only satisfy those requirements using a combination of in-engine measures and exhaust aftertreatment systems (SCR, particulate filters), which makes them a good deal more complex and expensive. In the face of CO{sub 2} emissions regulations and the growing demand for diesel fuel, greater emphasis is now being placed on alternative fuels. Homogeneous Charge Compression Ignition or 'HCCI' provides an alternative to complex exhaust aftertreatment systems which generates virtually no soot or nitrous oxide emissions. It does, however, present new challenges with respect to combustion control and engine load. Up to the present, it has not been possible to exploit the full potential of this combustion process over the entire engine map, since the high ignition performance of diesel fuel at high loads results in excessively early combustion and inadmissible pressure gradients. The pre-development department of MTU Friedrichshafen worked with the Institute of Internal Combustion Engines at the Karlsruhe Institute of Technology (KIT) to devise a research prototype for an industrial application which would allow semi-homogenous combustion with controlled self-ignition over the full engine map. The engine is based on a 6-cylinder version of the MTU Series 1600 unit and has a rated output of 300 kW. The fuels - gasoline or ethanol and diesel - are mixed in such a way as to avoid the disadvantages associated with most HCCI processes. Since the use of ethanol also enhances combustion efficiency, it has a two-fold positive effect on the CO{sub 2} situation. With

  15. PERFORMANCE, EMISSION, AND COMBUSTION CHARACTERISTICS OF A CI ENGINE USING LIQUID PETROLEUM GAS AND NEEM OIL IN DUAL FUEL MODE

    Directory of Open Access Journals (Sweden)

    Palanimuthu Vijayabalan

    2010-01-01

    Full Text Available Increased environmental awareness and depletion of resources are driving the industries to develop viable alternative fuels like vegetable oils, compresed natural gas, liquid petroleum gas, producer gas, and biogas in order to provide suitable substitute to diesel for compression ignition engine. In this investigation, a single cylinder, vertical, air-cooled diesel engine was modified to use liquid petroleum gas in dual fuel mode. The liquefied petroleum gas, was mixed with air and supplied through intake manifold. The liquid fuel neem oil or diesel was injected into the combustion chamber. The performance, emission, and combustion characteristics were studied and compared for neat fuel and dual fuel mode. The experimental results on dual fuel engine show a reduction in oxides of nitrogen up to 70% of the rated power and smoke in the entire power range. However the brake thermal efficiency was found decreased in low power range due to lower calorific value of liquid petroleum gas, and increase in higher power range due to the complete burning of liquid petroleum gas. Hydrocarbon and carbon monoxide emissions were increased significantly at lower power range and marginal variation in higher power range.

  16. Non-Petroleum-Based Fuels: Report on the Relationship Between Molecular Structure and Compression Ignition Fuels, Both Conventional and HCCI

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Joshua [National Renewable Energy Lab. (NREL), Golden, CO (United States); McCormick, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States); Clark, Wendy [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2004-08-01

    The U.S. Department of Energy (DOE) is committed to increasing our nation’s energy security by decreasing our dependence on imported petroleum. The Fuels Technologies Subprogram within DOE’s Office of Freedom Car and Vehicle Technology (OFCVT) supports research that allows the United States to develop advanced fuels that enable efficient engines with low emissions. This document reports the completion of NREL FY 2004 Annual Operating Plan milestone 10.2: “Report on the relationship between molecular structure and compression ignition fuels, both conventional and HCCI.” This work is an incremental step toward the OFCVT Multi-Year Program Plan APBF/NPBF Milestone No. 3: “Establish fuel and lubricant constituents that are required for advanced combustion regime engines.”

  17. Advanced Start of Combustion Sensor Phases I and II-A: Feasibility Demonstration, Design and Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Chad Smutzer

    2010-01-31

    Homogeneous Compressed Charge Ignition (HCCI) has elevated the need for Start of Combustion (SOC) sensors. HCCI engines have been the exciting focus of engine research recently, primarily because HCCI offers higher thermal efficiency than the conventional Spark Ignition (SI) engines and significantly lower NOx and soot emissions than conventional Compression Ignition (CI) engines, and could be fuel neutral. HCCI has the potential to unify all the internal combustion engine technology to achieve the high-efficiency, low-emission goal. However, these advantages do not come easy. It is well known that the problems encountered with HCCI combustion center on the difficulty of controlling the Start of Combustion. TIAX has an SOC sensor under development which has shown promise. In previous work, including a DOE-sponsored SBIR project, TIAX has developed an accelerometer-based method which was able to determine SOC within a few degrees crank angle for a range of operating conditions. A signal processing protocol allows reconstruction of the combustion pressure event signal imbedded in the background engine vibration recorded by the accelerometer. From this reconstructed pressure trace, an algorithm locates the SOC. This SOC sensor approach is nonintrusive, rugged, and is particularly robust when the pressure event is strong relative to background engine vibration (at medium to high engine load). Phase I of this project refined the previously developed technology with an engine-generic and robust algorithm. The objective of the Phase I research was to answer two fundamental questions: Can the accelerometer-based SOC sensor provide adequate SOC event capture to control an HCCI engine in a feedback loop? And, will the sensor system meet cost, durability, and software efficiency (speed) targets? Based upon the results, the answer to both questions was 'YES'. The objective of Phase II-A was to complete the parameter optimization of the SOC sensor prototype in order

  18. Advanced Start of Combustion Sensor Phases I and II-A: Feasibility Demonstration, Design and Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Chad Smutzer

    2010-01-31

    Homogeneous Compressed Charge Ignition (HCCI) has elevated the need for Start of Combustion (SOC) sensors. HCCI engines have been the exciting focus of engine research recently, primarily because HCCI offers higher thermal efficiency than the conventional Spark Ignition (SI) engines and significantly lower NOx and soot emissions than conventional Compression Ignition (CI) engines, and could be fuel neutral. HCCI has the potential to unify all the internal combustion engine technology to achieve the high-efficiency, low-emission goal. However, these advantages do not come easy. It is well known that the problems encountered with HCCI combustion center on the difficulty of controlling the Start of Combustion. TIAX has an SOC sensor under development which has shown promise. In previous work, including a DOE-sponsored SBIR project, TIAX has developed an accelerometer-based method which was able to determine SOC within a few degrees crank angle for a range of operating conditions. A signal processing protocol allows reconstruction of the combustion pressure event signal imbedded in the background engine vibration recorded by the accelerometer. From this reconstructed pressure trace, an algorithm locates the SOC. This SOC sensor approach is nonintrusive, rugged, and is particularly robust when the pressure event is strong relative to background engine vibration (at medium to high engine load). Phase I of this project refined the previously developed technology with an engine-generic and robust algorithm. The objective of the Phase I research was to answer two fundamental questions: Can the accelerometer-based SOC sensor provide adequate SOC event capture to control an HCCI engine in a feedback loop? And, will the sensor system meet cost, durability, and software efficiency (speed) targets? Based upon the results, the answer to both questions was 'YES'. The objective of Phase II-A was to complete the parameter optimization of the SOC sensor prototype in order

  19. Comparisons of Particulate Size Distributions from Multiple Combustion Strategies

    Science.gov (United States)

    Zhang, Yizhou

    In this study, a comparison of particle size distribution (PSD) measurements from eight different combustion strategies was conducted at four different load-speed points. The PSDs were measured using a scanning mobility particle sizer (SMPS) together with a condensation particle counter (CPC). To study the influence of volatile particles, PSD measurements were performed with and without a volatile particle remover (thermodenuder, TD) at both low and high dilution ratios. The common engine platform utilized in the experiment helps to eliminate the influence of background particulate and ensures similarity in dilution conditions. The results show a large number of volatile particles were present under LDR sample conditions for most of the operating conditions. The use of a TD, especially when coupled with HDR, was demonstrated to be effective at removing volatile particles and provided consistent measurements across all combustion strategies. The PSD comparison showed that gasoline premixed combustion strategies such as HCCI and GCI generally have low PSD magnitudes for particle sizes greater than the Particle Measurement Programme (PMP) cutoff diameter (23 nm), and the PSDs were highly nuclei-mode particle dominated. The strategies using diesel as the only fuel (DLTC and CDC) generally showed the highest particle number emissions for particles larger than 23 nm and had accumulation-mode particle dominated PSDs. A consistent correlation between the increase of the direct-injection of diesel fuel and a higher fraction of accumulation-mode particles was observed over all combustion strategies. A DI fuel substitution study and injector nozzle geometry study were conducted to better understand the correlation between PSD shape and DI fueling. It was found that DI fuel properties has a clear impact on PSD behavior for CDC and NG DPI. Fuel with lower density and lower sooting tendency led to a nuclei-mode particle dominated PSD shape. For NG RCCI, accumulation-mode

  20. Experimental investigation of CAI combustion in a two-stroke poppet valve DI engine

    OpenAIRE

    Zhang, Yan

    2015-01-01

    This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London Due to their ability to simultaneously reduce fuel consumption and NOx emissions, Controlled Auto Ignition (CAI) and HCCI combustion processes have been extensively researched over the last decade and adopted on prototype gasoline engines. These combustion processes were initially achieved on conventional two-stroke ported gasoline engines, but there have been significantly fewer stu...

  1. On-Board Engine Exhaust Particulate Matter Sensor for HCCI and Conventional Diesel Engines

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Matt; Matthews, Ron

    2011-09-30

    The goal of the research was to refine and complete development of an on-board particulate matter (PM) sensor for diesel, DISI, and HCCI engines, bringing it to a point where it could be commercialized and marketed.

  2. Fundamental study of the pulverized coal char combustion in oxyfuel mode with drop tube furnace

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Takamasa; Takafuji, Makoto; Suda, Toshiyuki; Fujimori, Toshiro [Heat and Fluid Dynamics Department, Yokohama (Japan)

    2013-07-01

    The combustion characteristics of coal char particles in either O{sub 2}/N{sub 2} or O{sub 2}/CO{sub 2} conditions were experimentally investigated. Especially, the char burnout, the char particle temperature and the shrinkage of the char particles were discussed. A Drop Tube Furnace (DTF: whose wall temperature was set at 873, 923 and 973 K) was used as the experimental apparatus. The experimental results revealed that, in equivalent oxygen concentration, the char burnout and the char particle temperature were higher in O{sub 2}/N{sub 2} conditions than those in O{sub 2}/CO{sub 2} conditions. The shrinkage of the char particle did not show the large difference in either O{sub 2}/N{sub 2} or O{sub 2}/CO{sub 2} conditions. Up to 15% of char burnout, the char particle diameters were reduced gradually. Up to 80% of char burnout, the char particle diameters were not changed. This is supposed that the chemical reaction is mainly occurred not on the external surface but on the internal surface of the char particle. Over 80% of char burnout, sudden shrinkage could be seen. Finally, an empirical equation for the prediction of the char particle shrinkage was introduced. Further investigation is required in high operating temperature, where CO{sub 2} gasification may have a large influence on the char burnout.

  3. A six-zone simulation model for HCCI engines with a non-segregated solver of zone state

    Science.gov (United States)

    Kozarac, Darko; Lulic, Zoran; Sagi, Goran

    2010-07-01

    A new six-zone simulation model for the calculation of changes in an HCCI engine has been developed and tested. The model uses comprehensive chemical kinetics and a non-sequential solver of zone states. This means that the state vector comprises the states in all zones, and that the changes in states in all zones are calculated simultaneously. In this manner, physical accuracy during the calculation of a new state is maintained at the expense of the calculation time. The model comprises the wall heat transfer, zone heat transfer and zone mass transfer as means of zone interactions. The cylinder is divided into two central zones, three boundary layer zones and one crevice zone. Since the model calculates only the high pressure part of an engine cycle, it has been connected with the cycle simulation software AVL Boost. In this way, a relatively easy-to-use, higher accuracy, simulation tool for HCCI engines has been obtained. The model was tested by comparing simulation results with experimental ones. The comparison was made with a single cylinder engine running on isooctane. The calculated pressure and net rate of heat release correspond to the experimental results very well in the entire operating region. By using the six-zone simulation model, a big improvement, compared to the single zone simulation, is obtained in operating points where combustion efficiency is over 90%. Results of emissions of unburned HC and CO show that predictions of these species are greatly improved, but it has also been noticed that these emissions are still slightly underpredicted. Predictions of emissions that come from crevice regions are good, but emissions that come from the corners of boundary layers are not captured very well. A detailed description of the simulation model is given, and validation results and possibilities of a further development are discussed.

  4. Experimental investigation of homogeneous charge compression ignition combustion of biodiesel fuel with external mixture formation in a CI engine.

    Science.gov (United States)

    Ganesh, D; Nagarajan, G; Ganesan, S

    2014-01-01

    In parallel to the interest in renewable fuels, there has also been increased interest in homogeneous charge compression ignition (HCCI) combustion. HCCI engines are being actively developed because they have the potential to be highly efficient and to produce low emissions. Even though HCCI has been researched extensively, few challenges still exist. These include controlling the combustion at higher loads and the formation of a homogeneous mixture. To obtain better homogeneity, in the present investigation external mixture formation method was adopted, in which the fuel vaporiser was used to achieve excellent HCCI combustion in a single cylinder air-cooled direct injection diesel engine. In continuation of our previous works, in the current study a vaporised jatropha methyl ester (JME) was mixed with air to form a homogeneous mixture and inducted into the cylinder during the intake stroke to analyze the combustion, emission and performance characteristics. To control the early ignition of JME vapor-air mixture, cooled (30 °C) Exhaust gas recirculation (EGR) technique was adopted. The experimental result shows 81% reduction in NOx and 72% reduction in smoke emission.

  5. Occurrence mode of chlorine in solid products from co-pyrolysis of coal and waste plastic and its emission characteristic during combustion

    Energy Technology Data Exchange (ETDEWEB)

    Li Zheng; Liu Ze-chang; Zhao Ying; Shi Yu-miao [Chemical and Environmental Engineering College of Shandong University of Science and Technology, Qingdao (China)

    2006-12-15

    The occurrence mode of chlorine in solid products from co-pyrolysis of coal and waste plastic was studied by IR and TG-MS. In addition, the emission characteristic of those solid products during combustion was studied. The results indicates that when co-pyrolysis temperature is below 600{sup o}C, there are some organic as well as inorganic chlorine compounds in coke; when the temperature is above 600{sup o}C, there is only inorganic one in the coke. The emission ratio of chlorine is relative to combustion temperature, the co-pyrolysing temperature as well as the percentage of PVC. The emission ratio of chlorine increases with the rising temperature of combustion. When the combustion temperature is 900{sup o}C, the emission ratio is up to 94%. On the contrary, the emission ratio is lower for the solid product from higher co-pyrolysis temperature as the combustion temperature is the same. The highest chlorine emission ratio from pyrolysis at 400{sup o}C is 99.86%, but that from 1000{sup o}C pyrolysis is 94.35%. 7 refs., 7 figs., 1 tab.

  6. An experimental study of different hydrocarbon components in natural gas and their impact on engine performance in a HCCI engine

    Energy Technology Data Exchange (ETDEWEB)

    Aaberg, Kristoffer

    2000-07-01

    Natural gas is a well suited fuel for HCCI (Homogenous Charge Compression Ignition) operation. Commercial natural gas consists of many different hydrocarbons where the lighter hydrocarbons, methane, ethane propane and butane are the most common and methane having the highest percentage. The composition of natural gas varies widely all over the world. It is well known that the higher hydrocarbons have a great impact on the ignition characteristics. As a spontaneous auto-ignition process initiates HCCI, this type of engine is very sensitive of the fuels ignition characteristics. To investigate the influence of the higher hydrocarbons an extensive test series was carried out. The impact of different concentrations of ethane, propane, iso- and n-butane were tested. Using different equivalence ratios, concentrations of the hydrocarbons, levels of EGR and levels of boost pressure the tests were carried out. Data collected during the testing were emission, mass flow, indicated mean effective pressure, inlet temperature and engine speed. From these data, specific emissions and efficiencies could be calculated. As a test a value of released heat per cycle was also evaluated, and used to check the mass flow. The results show that the ignition characteristics of the charge is very sensitive to fuel composition. A strong connection between the required inlet air temperature and the fuel composition was detected. With an increasing amount of heavier components in the gas, this temperature was decreased. This is connected to the octane number of the components. Much of the engine performance can be related to this change of temperature. Emissions and power output (imep) showed the highest dependency of the concentration of component gas. Butanes had the highest impact on the inlet temperature, followed by propane and ethane. With the use of 20% EGR the inlet temperature had to be raised. The impact of the component gases was the same as with no EGR. The combustion efficiency

  7. 醇醚双燃料HCCI燃烧机理研究%HCCI Mechanism of Methanol/DME Dual Fuel

    Institute of Scientific and Technical Information of China (English)

    陈鹏; 孟忠伟; 张煜盛; 闫妍; 吴怡

    2014-01-01

    The detail mechanism of dimethyl ether (CH3OCHO) and methanol (CH3OH) was simplified by the method of sensitivity analysis and the reduced chemical kinetic model of methanol/DME HCCI was established .The model included 38 speciesand99elementreactionsandformaldehyde(CH2O),formicacid(HCO2H)andmethylformateformation(CH3OCHO) sub-models were specially added .The combustion and emission characteristics of methanol HCCI engine were analyzed with the model .The results show that the reduced model agrees well with the detailed one in the aspects of heat release timing ,cumula-tive thermal effect ,in-cylinder temperature and pressure curve and has shorter calculation time ,which lays the foundation for improving the multi-dimension numerical simulation of chemical reaction flow .%采用敏感度分析法对二甲醚(CH3 OCH3)、甲醇(CH3 OH)详细机理进行简化,构建可用于均质压缩燃烧(HCCI)过程的二甲醚-甲醇简化动力学模型,包括38个物种和99个基元反应,特别添加了非常规排放物甲醛(CH2O)、甲酸(HCO2 H)和甲酸甲酯(CH3OCHO)的生成子模型。应用该简化机理模型对甲醇 HCCI发动机的燃烧与排放特性进行的算例分析表明,简化机理模型在燃烧放热特征时刻、燃烧累积热效应以及发动机缸内温度和压力曲线的预测值均与详细模型的计算值较为吻合,计算时间缩短,为提高化学反应流多维数值模拟的计算效率奠定了基础。

  8. Dilution effects on the controlled auto-ignition (CAI) combustion of hydrocarbon and alcohol fuels

    OpenAIRE

    Oakley, A.; Zhao, H.; Ma, T.; Ladommatos, N

    2001-01-01

    Copyright © 2001 SAE International. This paper is posted on this site with permission from SAE International. Further use of this paper is not permitted without permission from SAE This paper presents results from an experimental programme researching the in-cylinder conditions necessary to obtain homogenous CAI (or HCCI) combustion in a 4-stroke engine. The fuels under investigation include three blends of Unleaded Gasoline, a 95 RON Primary Reference Fuel, Methanol, and Ethanol. This wor...

  9. Kinetic modelling of a surrogate diesel fuel applied to 3D auto-ignition in HCCI engines

    CERN Document Server

    Bounaceur, Roda; Fournet, René; Battin-Leclerc, Frédérique; Jay, S; Da Cruz, A Pires

    2007-01-01

    The prediction of auto-ignition delay times in HCCI engines has risen interest on detailed chemical models. This paper described a validated kinetic mechanism for the oxidation of a model Diesel fuel (n-decane and α-methylnaphthalene). The 3D model for the description of low and high temperature auto-ignition in engines is presented. The behavior of the model fuel is compared with that of n-heptane. Simulations show that the 3D model coupled with the kinetic mechanism can reproduce experimental HCCI and Diesel engine results and that the correct modeling of auto-ignition in the cool flame region is essential in HCCI conditions.

  10. A University Consortium on Low Temperature Combustion for High Efficiency, Ultra-Low Emission Engines

    Energy Technology Data Exchange (ETDEWEB)

    Assanis, Dennis N. [Univ. of Michigan, Ann Arbor, MI (United States); Atreya, Arvind [Univ. of Michigan, Ann Arbor, MI (United States); Chen, Jyh-Yuan [Univ. of California, Berkeley, CA (United States); Cheng, Wai K. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Dibble, Robert W. [Univ. of California, Berkeley, CA (United States); Edwards, Chris [Stanford Univ., CA (United States); Filipi, Zoran S. [Univ. of Michigan, Ann Arbor, MI (United States); Gerdes, Christian [Stanford Univ., CA (United States); Im, Hong [Univ. of Michigan, Ann Arbor, MI (United States); Lavoie, George A. [Univ. of Michigan, Ann Arbor, MI (United States); Wooldridge, Margaret S. [Univ. of Michigan, Ann Arbor, MI (United States)

    2009-12-31

    The objective of the University consortium was to investigate the fundamental processes that determine the practical boundaries of Low Temperature Combustion (LTC) engines and develop methods to extend those boundaries to improve the fuel economy of these engines, while operating with ultra low emissions. This work involved studies of thermal effects, thermal transients and engine management, internal mixing and stratification, and direct injection strategies for affecting combustion stability. This work also examined spark-assisted Homogenous Charge Compression Ignition (HCCI) and exhaust after-treatment so as to extend the range and maximize the benefit of Homogenous Charge Compression Ignition (HCCI)/ Partially Premixed Compression Ignition (PPCI) operation. In summary the overall goals were; Investigate the fundamental processes that determine the practical boundaries of Low Temperature Combustion (LTC) engines; Develop methods to extend LTC boundaries to improve the fuel economy of HCCI engines fueled on gasoline and alternative blends, while operating with ultra low emissions; and Investigate alternate fuels, ignition and after-treatment for LTC and Partially Premixed compression Ignition (PPCI) engines.

  11. Combustion Characteristics of C5 Alcohols and a Skeletal Mechanism for Homogeneous Charge Compression Ignition Combustion Simulation

    KAUST Repository

    Park, Sungwoo

    2015-10-27

    C5 alcohols are considered alternative fuels because they emit less greenhouse gases and fewer harmful pollutants. In this study, the combustion characteristics of 2-methylbutanol (2-methyl-1-butanol) and isopentanol (3-methyl-1-butanol) and their mixtures with primary reference fuels (PRFs) were studied using a detailed chemical kinetic model obtained from merging previously published mechanisms. Ignition delay times of the C5 alcohol/air mixtures were compared to PRFs at 20 and 40 atm. Reaction path analyses were conducted at intermediate and high temperatures to identify the most influential reactions controlling ignition of C5 alcohols. The direct relation graph with expert knowledge methodology was used to eliminate unimportant species and reactions in the detailed mechanism, and the resulting skeletal mechanism was tested at various homogeneous charge compression ignition (HCCI) engine combustion conditions. These simulations were used to investigate the heat release characteristics of the methyl-substituted C5 alcohols, and the results show relatively strong reactions at intermediate temperatures prior to hot ignition. C5 alcohol blending in PRF75 in HCCI combustion leads to a significant decrease of low-temperature heat release (LTHR) and a delay of the main combustion. The heat release features demonstrated by C5 alcohols can be used to improve the design and operation of advanced engine technologies.

  12. A Chemical Kinetic Model of PRF Oxidation for HCCI Engine I:Comparison of existing models%适用于HCCI发动机的基础燃料化学动力学模型Ⅰ:比较现有模型

    Institute of Scientific and Technical Information of China (English)

    郑朝蕾; 张庆峰; 何祖威; 王迎

    2011-01-01

    随着HCCI燃烧技术的不断发展,燃料化学动力学机理在燃烧计算中发挥着越来越重要的作用.纵览了近年来基础燃料各种不同类型反应机理与试验研究情况,为评价现有反应机理对HCCI发动机燃烧过程的适用性,将机理模型的计算结果与HCCI燃烧相关试验进行了综合比较验证.通过4种典型基础燃料机理的计算与激波管、速压机和HCCI发动机等试验数据的比较发现,由于各反应机理构建的目的和方法不同,以及针对个别验证试验作出的参数调整,各机理在不同试验状况下性能各异,为此提出了构建适用于HCCI发动机的基础燃料简化机理的必要性.%With the development of homogenous charge compression ignition (HCCI) combustion technology, the chemical kinetic mechanism becomes more important. An review on the currently available primary reference fuels (PRF)oxidation mechanisms and experiments is discussed. The mechanisms need to be compared with experiments of HCCI combustion to evaluate the prediction in HCCI engine. Comparisons of experimental data include those from shock tube, rapid compression machine, and HCCI engine with calculated results using four typical reaction mechanisms indicate that different models from different experimental conditions are presented due to different purposes and approaches, and adjusting parameters for specified validated experiment during mechanism construction. The necessity in developing PRF reduced mechanism for HCCI combustion is addressed.

  13. The Development of a Rebust Accelerometer-Based Start of Combustion Sensing System

    Energy Technology Data Exchange (ETDEWEB)

    Jim Huang; David Mumford

    2009-01-31

    The development of modern combustion systems increasingly relies on detailed knowledge of the combustion event. As the limits of combustion are approached, tight control of combustion leads to improved emissions and higher efficiencies, while retaining and even improving engine reliability and durability. While developing a novel HCCI (Homogeneous Charge Compression Ignition) technology for large natural gas engines, Westport found that there was no reliable cost-effective technology to monitor the combustion event. As a result, Westport began working on developing a solution based on commercially available knock sensors. While initially developed around HCCI, Westport has identified that numerous other forms of combustion (high EGR systems, Homogeneous Charge Direct Injection, etc) will require combustion sensors. This requirement is also reflected in the development of other technologies in this field. However, the potential low system cost and the lack of intrusion into the cylinder head area are significant benefits for the Westport approach. Previous work by Westport has proven the method on two different large compression ignition gas engines. The objective of the current work is to improve the robustness of this technology; particularly, to identify and reduce the sensor-to-sensor and engine-to-engine variations.

  14. Pneumatic-Combustion Hybrid Engine: A Study of the Effect of the Valvetrain Sophistication on Pneumatic Modes Moteur hybride pneumatique: une étude de l’effet de la complexité de la distribution sur les modes pneumatiques

    Directory of Open Access Journals (Sweden)

    Brejaud P.

    2009-09-01

    Full Text Available Although internal combustion engines display high overall maximum global efficiencies, this potential cannot be fully exploited in automotive applications: in real conditions, the average engine load (and thus efficiency is quite low and the kinetic energy during a braking phase is lost. This work presents a hybrid pneumatic-combustion engine and the associated thermodynamic cycles, which is able to store and recover energy in the form of compressed air. The study focuses on the two major pneumatic modes: pneumatic pump mode and pneumatic motor mode. For each of them, three valvetrain technologies are considered: 4-stroke mode, 4-stroke mode with one camshaft disengaged, and 2-stroke fully variable. The concept can be adapted to SI or CI engines. In any case the valvetrain technology is the key to best fuel economy. A kinematic model of the charging valve’s actuator is introduced, and implemented in a quasi dimensional model of the pneumatic-combustion hybrid engine. Simulation results are presented for each pneumatic mode, for each valvetrain technology, in order to determine the best valve train configuration, and to show the impact of the kinematic valve actuator on the performance of the engine The tradeoffs between valvetrain sophistication and fuel economy will be presented for each case. Bien que le rendement total d’un moteur à combustion interne soit élevé, ce potentiel ne peut être pleinement exploité sur une automobile : dans les conditions réelles d’utilisation, la charge moteur moyenne (et donc le rendement est souvent faible. De plus, l’énergie cinétique en phase de freinage est totalement dissipée sous forme de chaleur. Cet article présente un concept de moteur hybride pneumatique, et les cycles thermodynamiques associés, capable de stocker de l’énergie (et de la réutiliser sous forme d’air comprimé. Le concept est adaptable au moteur à allumage commandé aussi bien qu’au moteur à allumage par

  15. HCCI Misfire Control Based on Ion Current Integral Signal%基于离子电流积分信号的HCCI失火控制

    Institute of Scientific and Technical Information of China (English)

    张栖玉; 张志永; 李从跃; 李理光

    2011-01-01

    A test bench for HCCI gasoline engine is built, in which the proper parameters of ion current detection system and its signal integral circuit are determined through tests. The features of ion current integral signal and its correlation with combustion are then analyzed. Finally an experimental study is conducted for the misfire cycle of HCCI engine in low-speed light load condition on the closed-loop control of in-cycle re-ignition based on ion current integral signal feedback. The results show that ion current integral signal can be taken as misfire criterion, and in-cycle re-ignition can effectively ignite mixture and hence reduce HC emission.%搭建了HCCI汽油机试验台,并通过试验为其离子电流检测系统及其信号积分电路选定合适的参数.分析了不同燃烧工况下的离子电流积分信号特征及其与燃烧的相关性,最后对低速小负荷工况HCCI失火循环进行了基于离子电流积分信号反馈的循环内补火闭环控制的试验研究,结果表明,离子电流积分信号可作为失火的判断标准,而循环内补火可有效地引燃混合气,降低HC排放.

  16. Evaluation of Closed-Loop Control Strategy of HCCI/SI Gasoline Engine in Driving Cycles%HCCI/SI复合模式汽油机闭环控制策略的整车驾驶循环评估

    Institute of Scientific and Technical Information of China (English)

    谢辉; 李楠; 周能辉; 赵华

    2008-01-01

    HCCI燃烧应用于实际车辆,面临燃烧闭环控制、动态过程控制及HCCI/SI模式过渡控制等难点问题.本文针对这些问题展开研究,基于GT-power软件建立了四缸HCCI/SI复合模式汽油机模型及轿车动力学模型,采用Simulink软件建立了HCCI/SI复合模式汽油机分层闭环控制器.通过典型驾驶过程以及NEDC循环的仿真,对HCCI/SI发动机闭环控制器的动态控制能力和模式切换控制能力进行了研究,详细考察了HCCI/SI复合模式汽油机轿车的燃油经济性的改善效果.仿真结果表明,HCCI/SI复合模式汽油机及其控制器可以实现驾驶过程中HCCI与SI模式的比较平滑的过渡,满足车辆行驶的动力需求,并显示出良好的经济性,在整个NEDC循环中比原机节油12.2%.

  17. Chemical Kinetics of Hydrocarbon Ignition in Practical Combustion Systems

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, C.K.

    2000-07-07

    Chemical kinetic factors of hydrocarbon oxidation are examined in a variety of ignition problems. Ignition is related to the presence of a dominant chain branching reaction mechanism that can drive a chemical system to completion in a very short period of time. Ignition in laboratory environments is studied for problems including shock tubes and rapid compression machines. Modeling of the laboratory systems are used to develop kinetic models that can be used to analyze ignition in practical systems. Two major chain branching regimes are identified, one consisting of high temperature ignition with a chain branching reaction mechanism based on the reaction between atomic hydrogen with molecular oxygen, and the second based on an intermediate temperature thermal decomposition of hydrogen peroxide. Kinetic models are then used to describe ignition in practical combustion environments, including detonations and pulse combustors for high temperature ignition, and engine knock and diesel ignition for intermediate temperature ignition. The final example of ignition in a practical environment is homogeneous charge, compression ignition (HCCI) which is shown to be a problem dominated by the kinetics intermediate temperature hydrocarbon ignition. Model results show why high hydrocarbon and CO emissions are inevitable in HCCI combustion. The conclusion of this study is that the kinetics of hydrocarbon ignition are actually quite simple, since only one or two elementary reactions are dominant. However, there are many combustion factors that can influence these two major reactions, and these are the features that vary from one practical system to another.

  18. TOXIC SUBSTANCES FROM COAL COMBUSTION--A COMPREHENSIVE ASSESSMENT, PHASE II: ELEMENT MODES OF OCCURRENCE FOR THE OHIO 5/6/7, WYODAK AND NORTH DAKOTA COAL SAMPLES

    Energy Technology Data Exchange (ETDEWEB)

    Allan Kolker; Stanley J. Mroczkowski; Curtis A. Palmer; Kristen O. Dennen; Robert B. Finkelman; John H. Bullock Jr.

    2002-05-30

    This study reports on the second phase (Phase II) of USGS research activities in support of DOE contract DE-AC22-95PC95101 ''Toxic Substances From Coal Combustion--A Comprehensive Assessment'', funded under DOE Interagency Agreement DE-AI22-95PC95145. The purpose of the study was to provide a quantitative and semi-quantitative characterization of the modes of occurrence of trace elements in coal samples investigated under Phase II, including (1) Ohio 5/6/7, an Ohio bituminous coal sample blended from the No.5, No.6, and No.7 beds; (2) North Dakota, a lignite sample from the Falkirk Mine, Underwood, ND, and (3) Wyodak, a sub-bituminous coal sample from the Cordero Mine, Gillette, WY. Samples from these coal beds were selected for their range in rank and commercial applicability. Results of this research provide basic information on the distribution of elements in Phase II coal samples, information needed for development of a commercial predictive model for trace-element behavior during coal combustion.

  19. Formation of Ti5Si3 by Combustion Synthesis in a Self-Propagating Mode: Experimental Study and Numerical Simulation

    Science.gov (United States)

    Yeh, C. L.; Chou, C. C.; Hwang, P. W.

    2016-09-01

    Titanium silicide (Ti5Si3) was fabricated by self-propagating high-temperature synthesis (SHS) from the elemental powder compact. With the increase of sample density from 50 to 60% TMD, experiments showed that the flame-front velocity increased from 28 to 50 mm/s and combustion temperature from 1,580 to 1,700°C. Based on their dependence, the activation energy of the synthesis reaction, Ea=193 kJ/mol, was deduced. By numerical simulation of combustion wave kinetics, the Arrhenius factor of the rate function, K0=3×109 s-1, was determined for the 5Ti + 3Si reaction system. The effect of sample compaction density on the SHS process was correlated to the variation of the effective thermal conductivity (keff) of the powder compact. The ratio of keff/kbulk=0.02-0.05 was numerically obtained for the 5Ti + 3Si samples with 50-60% TMD and well validated by the experimental data.

  20. Real-time, adaptive machine learning for non-stationary, near chaotic gasoline engine combustion time series.

    Science.gov (United States)

    Vaughan, Adam; Bohac, Stanislav V

    2015-10-01

    Fuel efficient Homogeneous Charge Compression Ignition (HCCI) engine combustion timing predictions must contend with non-linear chemistry, non-linear physics, period doubling bifurcation(s), turbulent mixing, model parameters that can drift day-to-day, and air-fuel mixture state information that cannot typically be resolved on a cycle-to-cycle basis, especially during transients. In previous work, an abstract cycle-to-cycle mapping function coupled with ϵ-Support Vector Regression was shown to predict experimentally observed cycle-to-cycle combustion timing over a wide range of engine conditions, despite some of the aforementioned difficulties. The main limitation of the previous approach was that a partially acasual randomly sampled training dataset was used to train proof of concept offline predictions. The objective of this paper is to address this limitation by proposing a new online adaptive Extreme Learning Machine (ELM) extension named Weighted Ring-ELM. This extension enables fully causal combustion timing predictions at randomly chosen engine set points, and is shown to achieve results that are as good as or better than the previous offline method. The broader objective of this approach is to enable a new class of real-time model predictive control strategies for high variability HCCI and, ultimately, to bring HCCI's low engine-out NOx and reduced CO2 emissions to production engines.

  1. Influence of EGR compounds on the oxidation of an HCCI-diesel surrogate

    CERN Document Server

    Anderlohr, Jörg; Da Cruz, A Pires; Bounaceur, Roda; Battin-Leclerc, Frédérique; Dagaut, Philippe; Montagne, X; 10.1016/j.proci.2008.06.019

    2009-01-01

    This paper presents an experimental and numerical study of the impact of various additives on the oxidation of a typical automotive surrogate fuel blend, i.e. n-heptane and toluene. It examines the impact of engine re-cycled exhaust has compounds on the control of an Homogeneous Charge Compression-Ignition (HCCI) engine. Series of experiments were performed in a hihly diluted Jet-Stirred Reactor (JDR) at pressures of 1 and 10 atm (1 atm = 101,325 Pa). The chosen thermo-chemical conditions were close to those characteristices of the pre-ignition period in an HCCI engine. The influence of various additives, namely nitric oxide (NO), ethylene (C2H4) and methanol (CH3OH), on the oxidation of a n-heptane/toluene blend was studied over a wide range of temperatures (550-1100 K), including the zone of the Negative Temperature Coefficient (NTC).

  2. Progressive combustion in SI-Engines—Experimental investigation on influence of combustion related parameters

    Indian Academy of Sciences (India)

    R Harish Kumar; A J Antony

    2008-12-01

    The fuel heat release rate which virtually controls the combustion process is dependent on the ‘Mass-Fraction-Burnt (MFB)’. In the present research work, a ‘logistic model with conditional variability in MFB’, has been developed for precise simulation of combustion in SI engines as the model has built in routines to take into account such factors as location of spark plug, single/dual spark plugs, intake generated swirl, combustion chamber geometry (associated with Bore/Stroke ratio), etc. A major contribution of this paper is that new and improved models for the ‘overall combustion duration’, and ‘ignition delay/flame development angle’, taking into account primarily the influence of compression ratio on the overall combustion process in SI engine have been developed. Taylor’s original equation for estimating the overall combustion duration has been modified by including a logistic equation for the error term and incorporating it in the original equation. Ignition delay as proposed by Keck et al has been modified by incorporating a polynomial of 3rd order into the original equation. The empirical correlations that have been proposed in this paper may serve to be the starting point for simulation of ‘photodetonation concept’ to simulate HCCI combustion which is presently the hot research work in the area of pre-mixed combustion. A program in Turbo-C++ has been developed for the complete simulation of SI engine combustion, taking into account the conditional variability effect, variable specific heats of burnt gases, dissociation of gases at high temperatures, progressive combustion phenomena, heat transfer (based on Woschni‘s equation), gas exchange process based on 1D-steady gas flow equation employing Taylor’s mach index of 0·6 for valve design.

  3. Numerical studies of combustion mode influence on the performance of UCC combustor%超紧凑燃烧室燃烧组织方式影响燃烧性能的数值研究

    Institute of Scientific and Technical Information of China (English)

    杨阳; 王力军

    2015-01-01

    Taking the design testing model of UCC combustor as the research object,numerical simulation of high speed rotating turbulent flow is conducted with Realizable k-ε turbulence model,so is simulation of combustion reaction with non-premixed PDF combustion model. Through the comparison and analysis of the combustion performance such as temperature distribution,quality of outlet temperature field,combustion effi-ciency and pollutant emission under three different combustion modes like the lean-fuel combustion,the stoi-chiometric ratio combustion and rich-fuel combustion,the influence of combustion mode on the performance of ultra-compact combustor is examined. Lean combustion mode has a greater impact on the combustion in the cavity. In the rich-fuel combustion,flame connected in the bottom of the cavity and mixed with the pri-mary air stream through the radial chute,and complete combustion was achieved. Combustion efficiency, quality of outlet temperature field and pollutant emission are better in lean-fuel combustion mode. The results are consistent well with other similar studies in the combustor center area,and have referential value to the UCC combustor design.%以试验室的超紧凑燃烧室设计模型为研究对象,用Realizable k-ε湍流模型模拟高速旋转湍流,用非预混燃烧的混合分数/PDF模型模拟燃烧反应。通过超紧凑型燃烧室在贫油燃烧、化学当量比燃烧和富油燃烧等不同燃烧组织方式下的燃烧温场、出口温度场品质、燃烧效率以及污染物排放等燃烧性能的对比分析,研究了不同的燃烧组织方式对超紧凑燃烧室的燃烧性能影响。贫油燃烧组织方式对环形凹腔内燃烧影响较大,对于当量比增大的富油燃烧组织方式,火焰在凹腔底部连通,并通过叶片径向斜槽与一次空气流混合并实现完全燃烧;贫油燃烧方式的燃烧效率、出口温度品质和污染物排放等燃烧性能较好。计算结

  4. Laser-assisted homogeneous charge ignition in a constant volume combustion chamber

    Science.gov (United States)

    Srivastava, Dhananjay Kumar; Weinrotter, Martin; Kofler, Henrich; Agarwal, Avinash Kumar; Wintner, Ernst

    2009-06-01

    Homogeneous charge compression ignition (HCCI) is a very promising future combustion concept for internal combustion engines. There are several technical difficulties associated with this concept, and precisely controlling the start of auto-ignition is the most prominent of them. In this paper, a novel concept to control the start of auto-ignition is presented. The concept is based on the fact that most HCCI engines are operated with high exhaust gas recirculation (EGR) rates in order to slow-down the fast combustion processes. Recirculated exhaust gas contains combustion products including moisture, which has a relative peak of the absorption coefficient around 3 μm. These water molecules absorb the incident erbium laser radiations ( λ=2.79 μm) and get heated up to expedite ignition. In the present experimental work, auto-ignition conditions are locally attained in an experimental constant volume combustion chamber under simulated EGR conditions. Taking advantage of this feature, the time when the mixture is thought to "auto-ignite" could be adjusted/controlled by the laser pulse width optimisation, followed by its resonant absorption by water molecules present in recirculated exhaust gas.

  5. 当量比对燃烧模态的影响机理分析%Mechanism Analysis for Effects of Equivalence Ratio on Combustion Mode

    Institute of Scientific and Technical Information of China (English)

    王西耀; 肖保国; 田野; 晏至辉

    2015-01-01

    To analyze the effects of fuel-air ratio on combustion modes more deeply,the flow-fields of scram⁃jet with different fuel-air ratio were acquired with experiment and CFD method. The method to calculate the heat release rate was presented. The CFD flow-fields were validated by experiments. With CFD results ,a feedback bal⁃ance between heat release and flow velocity was presented,which can be used to explain the mechanism of com⁃bustion modes formation. Three combustion modes and their characteristics were presented. In scramjet mode ,the heat release is distributed,the flow in combustor is supersonic,and there is no separation in isolator. In ramjet mode,the heat release is concentrated,the flow in combustor is subsonic,and there is large separation and strong shock train in isolator. In dual mode,the heat release is concentrated,in combustor the subsonic flow and super⁃sonic flow exist at the same time and there is large separation and strong shock train in isolator. Finally ,a method to achieve scramjet mode under the condition of large fuel-air ratio was presented,that means putting a part of fu⁃el at the divergent part of the combustor to make sure the heat release is distributed.%为了深入分析当量比对燃烧模态的影响机理,通过试验和计算研究了不同当量比条件下超燃冲压发动机燃烧室流场,给出了释热速率的计算方法。结果表明,数值模拟结果具有一定的可靠性,并基于数值模拟结果,提出了模态形成过程中释热和流动速度的反馈平衡机理。给出了三种燃烧模态及其特征,超燃模态,燃烧释热为分布式,燃烧室流动速度为超声速,隔离段无分离;亚燃模态,燃烧释热为集中式,燃烧室流动为亚声速,隔离段存在大分离以及强激波串;混合模态,燃烧释热为集中式,燃烧室流动同时存在亚声速和超声速,隔离段存在大分离以及强激波串。提出了高当量比条件下

  6. Internal combustion engine report: Spark ignited ICE GenSet optimization and novel concept development

    Energy Technology Data Exchange (ETDEWEB)

    Keller, J.; Blarigan, P. Van [Sandia National Labs., Livermore, CA (United States)

    1998-08-01

    In this manuscript the authors report on two projects each of which the goal is to produce cost effective hydrogen utilization technologies. These projects are: (1) the development of an electrical generation system using a conventional four-stroke spark-ignited internal combustion engine generator combination (SI-GenSet) optimized for maximum efficiency and minimum emissions, and (2) the development of a novel internal combustion engine concept. The SI-GenSet will be optimized to run on either hydrogen or hydrogen-blends. The novel concept seeks to develop an engine that optimizes the Otto cycle in a free piston configuration while minimizing all emissions. To this end the authors are developing a rapid combustion homogeneous charge compression ignition (HCCI) engine using a linear alternator for both power take-off and engine control. Targeted applications include stationary electrical power generation, stationary shaft power generation, hybrid vehicles, and nearly any other application now being accomplished with internal combustion engines.

  7. A Physics and Tabulated Chemistry Based Compression Ignition Combustion Model: from Chemistry Limited to Mixing Limited Combustion Modes Un modèle de combustion à allumage par compression basé sur la physique et la chimie tabulée : des modes de combustion contrôlés par la chimie jusqu’aux modes contrôlés par le mélange

    Directory of Open Access Journals (Sweden)

    Bordet N.

    2011-11-01

    Full Text Available This paper presents a new 0D phenomenological approach to predict the combustion process in multi injection Diesel engines operated under a large range of running conditions. The aim of this work is to develop a physical approach in order to improve the prediction of in-cylinder pressure and heat release. Main contributions of this study are the modeling of the premixed part of the Diesel combustion with a further extension of the model for multi-injection strategies. In the present model, the rate of heat release due to the combustion for the premixed phase is related to the mean reaction rate of fuel which is evaluated by an approach based on tabulated local reaction rate of fuel and on the determination of the Probability Density Function (PDF of the mixture fraction (Z, in order to take into consideration the local variations of the fuel-air ratio. The shape of the PDF is presumed as a standardized β-function. Mixture fraction fluctuations are described by using a transport equation for the variance of Z. The standard mixture fraction concept established in the case of diffusion flames is here adapted to premixed combustion to describe inhomogeneity of the fuel-air ratio in the control volume. The detailed chemistry is described using a tabulated database for reaction rates and cool flame ignition delay as a function of the progress variable c. The mixing-controlled combustion model is based on the calculation of a characteristic mixing frequency which is a function of the turbulence density, and on the evolution of the available fuel vapor mass in the control volume. The developed combustion model is one sub-model of a thermodynamic model based on the mathematical formulation of the conventional two-zone approach. In addition, an extended sub-model for multi injection is developed to take into account interactions between each spray by describing their impact on the mixture formation. Numerical results from simulations are compared with

  8. Combustion and Emission Characteristics of Turbocharged Common-Rail Diesel Engine with DMCC Mode%柴油/甲醇组合燃烧增压共轨发动机的燃烧特性和排放特性

    Institute of Scientific and Technical Information of China (English)

    姚春德; 夏琦; 陈绪平; 阳向兰; 魏立江; 刘军恒

    2011-01-01

    在增压共轨发动机上采用柴油,甲醇组合燃烧(DMCC)方式进行燃烧特性分析和排放特性分析.对DMCC模式下放热率、缸内压力变化和p-V图的分析表明,DMCC模式具有吸热汽化、推迟着火时间、提高定容燃烧度、降低排气温度等优点,从而大幅度提高了燃料的燃烧效率.对M100(纯甲醇)和M90(含水10%的甲醇)的排放量进行检测,表明M90比M100更能降低甲醛、NOJ、HC和CO排放.%The combustion and emission characteristics of a turbocharged common-rail diesel engine have been experimentally investigated using diesel/methanol compound combustion mode (DMCC). The ahalysis of heat release rate, pressure change in cylinder and p-V diagram shows that DMCC mode has the advantages of endothermic vaporization, delaying ignition time, increasing constant volume combustion and decreasing exhaust temperature,thus greatly improving fuel combustion efficiency. The emission test shows that M90 (contain 10% water) is more effective than M100 (pure methanol) in reducing formaldehyde, NOx, HC and CO emissions.

  9. Combustion of coffee husks

    Energy Technology Data Exchange (ETDEWEB)

    Saenger, M.; Hartge, E.-U.; Werther, J. [Technical Univ. Hamburg-Harburg, Chemical Engineering 1, Hamburg (Germany); Ogada, T.; Siagi, Z. [Moi Univ., Dept. of Production Engineering, Eldoret (Kenya)

    2001-05-01

    Combustion mechanisms of two types of coffee husks have been studied using single particle combustion techniques as well as combustion in a pilot-scale fluidized bed facility (FBC), 150 mm in diameter and 9 m high. Through measurements of weight-loss and particle temperatures, the processes of drying, devolatilization and combustion of coffee husks were studied. Axial temperature profiles in the FBC were also measured during stationary combustion conditions to analyse the location of volatile release and combustion as a function of fuel feeding mode. Finally the problems of ash sintering were analysed. The results showed that devolatilization of coffee husks (65-72% volatile matter, raw mass) starts at a low temperature range of 170-200degC and takes place rapidly. During fuel feeding using a non water-cooled system, pyrolysis of the husks took place in the feeder tube leading to blockage and non-uniform fuel flow. Measurements of axial temperature profiles showed that during under-bed feeding, the bed and freeboard temperatures were more or less the same, whereas for over-bed feeding, freeboard temperatures were much higher, indicating significant combustion of the volatiles in the freeboard. A major problem observed during the combustion of coffee husks was ash sintering and bed agglomeration. This is due to the low melting temperature of the ash, which is attributed to the high contents of K{sub 2}O (36-38%) of the coffee husks. (Author)

  10. Combustion characteristics of turbo charged DISI-engines

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmeyer, Henrik

    2012-07-01

    In spite of progress in the development of alternative powertrain systems and energy sources, the internal combustion and all its derivates still are and will be the main powertrain for automobiles. In SI-engines, several approaches compete with each other like the controlled auto ignition (CAI or HCCI), throttle-free load control using variable valvetrains, stratified mixture formation with lean engine operation or highly turbo charged downsizing concepts all combined with gasoline direct injection. The presented work makes a contribution for a deeper understanding of the combustion process of a turbo charged direct injection engine operating with external EGR as well as lean stratified mixture. Using detailed test bench investigations and introducing a new optical measurement tool, the combustion process is described in detail focusing on the occurrence of non-premixed combustion phenomena. The influence of engine parameters like global and local air-/fuel ratio, external EGR and fuel rail pressure as well as the influence of fuel parameters are discussed giving a characterization of the combustion process of stratified engine operation. Furthermore, the influences of non-inert exhaust gas components on engine knock tendency are investigated using external EGR with an EGR catalyst. Opposing the results to numerical analysis, combustion characteristics of turbo charged DISI-engines are presented. (orig.)

  11. Numerical Analysis of Autoignition and Combustion of n-Butane and Air Mixture in Homogeneous-Charge Compression-Ignition Engine Using Elementary Reactions

    Science.gov (United States)

    Yamasaki, Yudai; Iida, Norimasa

    The present study focuses on clarifying the combustion mechanism of the homogeneous-charge compression-ignition (HCCI) engine in order to control ignition and combustion as well as to reduce HC and CO emissions and to maintain high combustion efficiency by calculating the chemical kinetics of elementary reactions. For the calculations, n-butane was selected as fuel since it is a fuel with the smallest carbon number in the alkane family that shows two-stage autoignition (heat release with low-temperature reaction (LTR) and with high-temperature reaction (HTR)) similarly to higher hydrocarbons such as gasoline. The CHEMKIN code was used for the calculations assuming zero dimensions in the combustion chamber and adiabatic change. The results reveal the heat release mechanism of the LTR and HTR, the control factor of ignition timing and combustion speed, and the condition need to reduce HC and CO emissions and to maintain high combustion efficiency.

  12. Advancing the Limits of Dual Fuel Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Koenigsson, Fredrik

    2012-07-01

    There is a growing interest in alternative transport fuels. There are two underlying reasons for this interest; the desire to decrease the environmental impact of transports and the need to compensate for the declining availability of petroleum. In the light of both these factors the Diesel Dual Fuel, DDF, engine is an attractive concept. The primary fuel of the DDF engine is methane, which can be derived both from renewables and from fossil sources. Methane from organic waste; commonly referred to as biomethane, can provide a reduction in greenhouse gases unmatched by any other fuel. The DDF engine is from a combustion point of view a hybrid between the diesel and the otto engine and it shares characteristics with both. This work identifies the main challenges of DDF operation and suggests methods to overcome them. Injector tip temperature and pre-ignitions have been found to limit performance in addition to the restrictions known from literature such as knock and emissions of NO{sub x} and HC. HC emissions are especially challenging at light load where throttling is required to promote flame propagation. For this reason it is desired to increase the lean limit in the light load range in order to reduce pumping losses and increase efficiency. It is shown that the best results in this area are achieved by using early diesel injection to achieve HCCI/RCCI combustion where combustion phasing is controlled by the ratio between diesel and methane. However, even without committing to HCCI/RCCI combustion and the difficult control issues associated with it, substantial gains are accomplished by splitting the diesel injection into two and allocating most of the diesel fuel to the early injection. HCCI/RCCI and PPCI combustion can be used with great effect to reduce the emissions of unburned hydrocarbons at light load. At high load, the challenges that need to be overcome are mostly related to heat. Injector tip temperatures need to be observed since the cooling effect of

  13. Estimation of trapped mass by in-cylinder pressure resonance in HCCI engines

    Science.gov (United States)

    Luján, José Manuel; Guardiola, Carlos; Pla, Benjamín; Bares, Pau

    2016-01-01

    High pressure gradients at homogeneous charge compression ignition (HCCI) engines heavily excite the pressure resonance. The pressure resonant frequency depends on speed of sound in the cylinder, and thus on the bulk gas temperature. Present paper profits this relation estimating the trapped mass inside the cylinder. In contrast to other estimation methods in the literature, the presented method is based on the trace of the in-cylinder pressure during the cycle; therefore, it permits a cycle-to-cycle mass estimation, and avoids errors associated with other assumptions, such as heat transfer during compression or initial temperature of the in-cylinder gases. The proposed strategy only needs the pressure signal, a volume estimation and a composition assumption to obtain several trapped mass estimates during one cycle. These estimates can be later combined for providing an error estimate of the measurement, with the assumption of negligible blow-by. The method is demonstrated in two HCCI engines of different size, showing good performance in steady operation and presenting great potential to control transient operation.

  14. Homojen Karışımlı Sıkıştırma Ateşlemeli (HCCI bir motorun tek-bölgeli modelleme yöntemi kullanılarak analizi

    Directory of Open Access Journals (Sweden)

    Halit Yaşar

    2016-12-01

    Full Text Available HCCI motorların modellenmesinde sıfır-boyutlu modeller yaygın olarak kullanılmaktadır. Bu modeller tek veya çok bölge içerebilirler. Bununla birlikte, en basit yaklaşım yanmış ve yanmamış gazı içeren tek bölge yaklaşımıdır. Bu tip sıfır-boyutlu modellerde yanma olayı Wiebe fonksiyonu ile modellenmektedir. Bu makalede, HCCI prensibine göre çalışan tek silindirli bir Ricardo Hydra motoru tek bölge yaklaşımı kullanılarak modellenmiştir. Analiz çalışmalarında SPICE (Simulated Petrol Internal Combustion Engine yazılımının modifiye edilmiş bir versiyonu olan TRICE yazılımı kullanılmıştır. Yanma analizlerinde, HCCI yanma modellerinde standart Wiebe fonksiyonu kullanımının maksimum silindir basıncının yüksek olarak tahmin edilmesi sonucunu doğurması nedeniyle, standart Wiebe fonksiyonunun modifiye edilmiş bir şekli olan Double-Wiebe fonksiyonu kullanılmıştır. Analizler, n-Heptan-Toluen karışımı için üç hava fazlalık katsayısı değerinde gerçekleştirilmiş ve elde edilen sonuçlar bir Avrupa Komisyonu Marie Curie destek programı (FP-6 projesi kapsamında Shell Araştırma Merkezine ait motor test laboratuvarında ölçülen deneysel verilerle karşılaştırılmıştır.

  15. Modeling of scalar dissipation rates in flamelet models for low temperature combustion engine simulations

    CERN Document Server

    Gupta, Saurabh; Pal, Pinaki; Im, Hong G

    2014-01-01

    The flamelet approach offers a viable framework for combustion modeling of homogeneous charge compression ignition (HCCI) engines under stratified mixture conditions. Scalar dissipation rate acts as a key parameter in flamelet-based combustion models which connects the physical mixing space to the reactive space. The aim of this paper is to gain fundamental insights into turbulent mixing in low temperature combustion (LTC) engines and investigate the modeling of scalar dissipation rate. Three direct numerical simulation (DNS) test cases of two-dimensional turbulent auto-ignition of a hydrogen-air mixture with different correlations of temperature and mixture fraction are considered, which are representative of different ignition regimes. The existing models of mean and conditional scalar dissipation rates, and probability density functions (PDFs) of mixture fraction and total enthalpy are a priori validated against the DNS data.

  16. Pneumatic-Combustion Hybrid Engine: A Study of the Effect of the Valvetrain Sophistication on Pneumatic Modes Moteur hybride pneumatique: une étude de l’effet de la complexité de la distribution sur les modes pneumatiques

    OpenAIRE

    Brejaud P.; Charlet A.; Chamaillard Y.; Ivanco A.; Higelin P.

    2009-01-01

    Although internal combustion engines display high overall maximum global efficiencies, this potential cannot be fully exploited in automotive applications: in real conditions, the average engine load (and thus efficiency) is quite low and the kinetic energy during a braking phase is lost. This work presents a hybrid pneumatic-combustion engine and the associated thermodynamic cycles, which is able to store and recover energy in the form of compressed air. The study focuses on the two maj...

  17. Key factors of combustion from kinetics to gas dynamics

    CERN Document Server

    Rubtsov, Nikolai M

    2017-01-01

    This book summarizes the main advances in the mechanisms of combustion processes. It focuses on the analysis of kinetic mechanisms of gas combustion processes and experimental investigation into the interrelation of kinetics and gas dynamics in gas combustion. The book is complimentary to the one previously published, The Modes of Gaseous Combustion.

  18. A comprehensive fractal char combustion model☆

    Institute of Scientific and Technical Information of China (English)

    Yuting Liu; Rong He

    2016-01-01

    The char combustion mechanisms were analyzed and a comprehensive fractal char combustion model was developed to give a better understanding and better predictions of the char combustion characteristics. Most of the complex factors affecting the char combustion were included, such as the coupling effects between the pore diffusion and the chemical reactions, the evolution of the char pore structures and the variation of the apparent reaction order during combustion, the CO/CO2 ratio in the combustion products and the correction for oxy-char combustion. Eleven different chars were then combusted in two drop tube furnaces with the conversions of the partly burned char samples measured by thermogravimetric analysis. The combustion processes of these chars were simulated with the predicted char conversions matching very well with the measured data which shows that this char combustion model has good accuracy. The apparent reaction order of the char combustion decreases, stabilizes and then increases during the combustion process. The combustion rates in the oxy-mode are general y slower than in the air-mode and the effect of the char-CO2 gasification reac-tion becomes obvious only when the temperature is relatively high and the O2 concentration is relatively low.

  19. Computational Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, C K; Mizobuchi, Y; Poinsot, T J; Smith, P J; Warnatz, J

    2004-08-26

    Progress in the field of computational combustion over the past 50 years is reviewed. Particular attention is given to those classes of models that are common to most system modeling efforts, including fluid dynamics, chemical kinetics, liquid sprays, and turbulent flame models. The developments in combustion modeling are placed into the time-dependent context of the accompanying exponential growth in computer capabilities and Moore's Law. Superimposed on this steady growth, the occasional sudden advances in modeling capabilities are identified and their impacts are discussed. Integration of submodels into system models for spark ignition, diesel and homogeneous charge, compression ignition engines, surface and catalytic combustion, pulse combustion, and detonations are described. Finally, the current state of combustion modeling is illustrated by descriptions of a very large jet lifted 3D turbulent hydrogen flame with direct numerical simulation and 3D large eddy simulations of practical gas burner combustion devices.

  20. Straw combustion on slow-moving grates

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    2005-01-01

    Combustion of straw in grate-based boilers is often associated with high emission levels and relatively poor fuel burnout. A numerical grate combustion model was developed to assist in improving the combustion performance of these boilers. The model is based on a one-dimensional ‘‘walking......-column’’ approach and includes the energy equations for both the fuel and the gas accounting for heat transfer between the two phases. The model gives important insight into the combustion process and provides inlet conditions for a computational fluid dynamics analysis of the freeboard. The model predictions...... indicate the existence of two distinct combustion modes. Combustion air temperature and mass flow-rate are the two parameters determining the mode. There is a significant difference in reaction rates (ignition velocity) and temperature levels between the two modes. Model predictions were compared...

  1. 乙醇汽油混合燃料直喷均质压燃爆震模型和试验研究%Experimental studies on knocking characteristics of DI-HCCI with gasoline/ethanol fuels

    Institute of Scientific and Technical Information of China (English)

    邓俊; 史现; 刘寅童; 吴志军; 李理光

    2013-01-01

    Knocking characteristics were investigated by using engine bench tests for a combustion of DI-HCCI (direct-injection homogeneous charge compression ignition) with blend fuels of ethanol and gasoline. Some improvements were done to a traditional two-cylinder diesel engine in fuel supply system, ignition system, and inlet and exhaust system. A knock model was established according to the engine bench tests and the cylinder pressure signals to describe ethanol and gasoline HCCI combustion. Knock intensity (KI) was drawn from the model and then was measured in the tests. The results show that the average KI and the knock probability signiifcantly decrease with the blending ratio of ethanol and gasoline, i.e. the percentage of ethanol increases, while the knock starting phase retards. Knock boundaries also narrow down with high blending ratio, while the upper and lower boundaries move towards each other. Those results could lead to the development of better fuel injection strategies.%为研究直接喷射(DI)式均质压燃(HCCI)爆震特性,进行了台架试验。改造了一台传统双缸柴油机的供油系统、点火系统、进排气机构,使其具有缸内直喷乙醇汽油混合燃料HCCI燃烧模式。根据该发动机台架的特点与缸压信号特征,建立了描述乙醇汽油HCCI燃烧的爆震模型,从模型中提取了爆震强度(KI),并进行了试验测量。结果表明:随乙醇在混合燃料中体积分数的升高,平均KI和爆震概率均有降低,爆震始点推后;爆震工况的当量比范围变窄,爆震工况上下边界互相靠拢。该结果有利于提出更合理的发动机喷射控制策略。

  2. Reduced chemical reaction mechanisms: experimental and HCCI modelling investigations of autoignition processes of iso-octane in internal combustion engines

    OpenAIRE

    Machrafi, Hatim; Lombaert, K.; Cavadias, S; Guibert, P.; Amouroux, J

    2005-01-01

    A semi-reduced (70 species, 210 reactions) and a skeletal (27 species, 29 reactions) chemical reaction mechanism for iso-octane are constructed from a semi-detailed iso-octane mechanism (84 species, 412 reactions) of the Chalmers University of Technology in Sweden. The construction of the reduced mechanisms is performed by using reduction methods such as the quasi-steady-state assumption and the partial equilibrium assumption. The obtained reduced iso-octane mechanisms show, at the mentioned ...

  3. Combustion Diagnostics by Pure Rotational Coherent Anti-Stokes Raman Scattering

    Science.gov (United States)

    Leipertz, Alfred; Seeger, Thomas

    Since its first use in Richard Chang's laboratory in 1982 in a comparative study with vibrational coherent anti-Stokes Raman scattering (VCARS) in a flame, pure rotational coherent anti-Stokes Raman scattering (RCARS) has gained tremendous importance for gas temperature and relative species concentration measurements in combustion diagnostics. The field of application covers basic studies on diagnostics development and on flame research as well as its use in technical combustion systems, e.g., for the determination of the gas-phase temperature in the vaporizing spray of a gasoline direct injection (GDI) injector or for the simultaneous measurement of gas temperature and exhaust-gas-recirculation rate (EGR rate) in a homogeneous charge compression ignition (HCCI) engine. An overview is given on the fundamentals of the technique and on its most important technical applications.

  4. Combustion physics

    Science.gov (United States)

    Jones, A. R.

    1985-11-01

    Over 90% of our energy comes from combustion. By the year 2000 the figure will still be 80%, even allowing for nuclear and alternative energy sources. There are many familiar examples of combustion use, both domestic and industrial. These range from the Bunsen burner to large flares, from small combustion chambers, such as those in car engines, to industrial furnaces for steel manufacture or the generation of megawatts of electricity. There are also fires and explosions. The bountiful energy release from combustion, however, brings its problems, prominent among which are diminishing fuel resources and pollution. Combustion science is directed towards finding ways of improving efficiency and reducing pollution. One may ask, since combustion is a chemical reaction, why physics is involved: the answer is in three parts. First, chemicals cannot react unless they come together. In most flames the fuel and air are initially separate. The chemical reaction in the gas phase is very fast compared with the rate of mixing. Thus, once the fuel and air are mixed the reaction can be considered to occur instantaneously and fluid mechanics limits the rate of burning. Secondly, thermodynamics and heat transfer determine the thermal properties of the combustion products. Heat transfer also plays a role by preheating the reactants and is essential to extracting useful work. Fluid mechanics is relevant if work is to be performed directly, as in a turbine. Finally, physical methods, including electric probes, acoustics, optics, spectroscopy and pyrometry, are used to examine flames. The article is concerned mainly with how physics is used to improve the efficiency of combustion.

  5. Applied combustion

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-31

    From the title, the reader is led to expect a broad practical treatise on combustion and combustion devices. Remarkably, for a book of modest dimension, the author is able to deliver. The text is organized into 12 Chapters, broadly treating three major areas: combustion fundamentals -- introduction (Ch. 1), thermodynamics (Ch. 2), fluid mechanics (Ch. 7), and kinetics (Ch. 8); fuels -- coal, municipal solid waste, and other solid fuels (Ch. 4), liquid (Ch. 5) and gaseous (Ch. 6) fuels; and combustion devices -- fuel cells (Ch. 3), boilers (Ch. 4), Otto (Ch. 10), diesel (Ch. 11), and Wankel (Ch. 10) engines and gas turbines (Ch. 12). Although each topic could warrant a complete text on its own, the author addresses each of these major themes with reasonable thoroughness. Also, the book is well documented with a bibliography, references, a good index, and many helpful tables and appendices. In short, Applied Combustion does admirably fulfill the author`s goal for a wide engineering science introduction to the general subject of combustion.

  6. Numerical modeling on homogeneous charge compression ignition combustion engine fueled by diesel-ethanol blends

    Directory of Open Access Journals (Sweden)

    Hanafi H.

    2016-01-01

    Full Text Available This paper investigates the performance and emission characteristics of HCCI engines fueled with oxygenated fuels (ethanol blend. A modeling study was conducted to investigate the impact of ethanol addition on the performance, combustion and emission characteristics of a Homogeneous Charge Compression Ignition (HCCI engine fueled by diesel. One dimensional simulation was conducted using the renowned commercial software for diesel and its blend fuels with 5% (E5 and 10% ethanol (E10 (in vol. under full load condition at variable engine speed ranging from 1000 to 2750 rpm with 250 rpm increment. The model was then validated with other researcher’s experimental result. Model consists of intake and exhaust systems, cylinder, head, valves and port geometries. Performance tests were conducted for volumetric efficiency, brake engine torque, brake power, brake mean effective pressure, brake specific fuel consumption, and brake thermal efficiency, while exhaust emissions were analyzed for carbon monoxide (CO and unburned hydrocarbons (HC. The results showed that blending diesel with ethanol increases the volumetric efficiency, brake specific fuel consumption and brake thermal efficiency, while it decreases brake engine torque, brake power and brake mean effective pressure. In term of emission characteristics, the CO emissions concentrations in the engine exhaust decrease significantly with ethanol as additive. But for HC emission, its concentration increase when apply in high engine speed. In conclusion, using Ethanol as fuel additive blend with Diesel operating in HCCI shows a good result in term of performance and emission in low speed but not recommended to use in high speed engine. Ethanol-diesel blends need to researched more to make it commercially useable.

  7. Combustion diagnostic for active engine feedback control

    Science.gov (United States)

    Green, Jr., Johney Boyd; Daw, Charles Stuart; Wagner, Robert Milton

    2007-10-02

    This invention detects the crank angle location where combustion switches from premixed to diffusion, referred to as the transition index, and uses that location to define integration limits that measure the portions of heat released during the combustion process that occur during the premixed and diffusion phases. Those integrated premixed and diffusion values are used to develop a metric referred to as the combustion index. The combustion index is defined as the integrated diffusion contribution divided by the integrated premixed contribution. As the EGR rate is increased enough to enter the low temperature combustion regime, PM emissions decrease because more of the combustion process is occurring over the premixed portion of the heat release rate profile and the diffusion portion has been significantly reduced. This information is used to detect when the engine is or is not operating in a low temperature combustion mode and provides that feedback to an engine control algorithm.

  8. Biofuels combustion.

    Science.gov (United States)

    Westbrook, Charles K

    2013-01-01

    This review describes major features of current research in renewable fuels derived from plants and from fatty acids. Recent and ongoing fundamental studies of biofuel molecular structure, oxidation reactions, and biofuel chemical properties are reviewed, in addition to combustion applications of biofuels in the major types of engines in which biofuels are used. Biofuels and their combustion are compared with combustion features of conventional petroleum-based fuels. Two main classes of biofuels are described, those consisting of small, primarily alcohol, fuels (particularly ethanol, n-butanol, and iso-pentanol) that are used primarily to replace or supplement gasoline and those derived from fatty acids and used primarily to replace or supplement conventional diesel fuels. Research efforts on so-called second- and third-generation biofuels are discussed briefly.

  9. Control of Ignition and Combustion of Dimethyl Ether in Homogeneous Charge Compression Ignition Engine

    Science.gov (United States)

    Kim, Kyoung-Oh; Azetsu, Akihiko; Oikawa, Chikashi

    A homogeneous charge compression ignition (HCCI) engine is known to have high thermal efficiency and low nitrogen oxide emission. However, the control of ignition timing and its combustion period over a wide range of engine speeds and loads is one of the barriers to the realization of the engine. On the lean side of the equivalence ratio, control of ignition is difficult due to its long delay of ignition, and there is knocklike problem under high load. In both computations and experiments of HCCI engine operated on dimethyl ether, the operable range (the possible range of fuel input from just ignitable to knock-occurring state) shifted to the rich side with decreasing intake temperature and amount of mixing of carbon dioxide. The range of fuel input was reduced at low intake temperatures, because the hot flame onset angle advanced more quickly than it did at high intake temperatures. However, the mixing of CO2 caused the operable range to shift to the rich side while retaining the same range. The results of this study indicated the possibility of high-load operation or extension of the load range by exhaust gas recirculation.

  10. Evaluation of in-cylinder mixture homogeneity in a diesel HCCI engine – A CFD analysis

    Directory of Open Access Journals (Sweden)

    N. Ramesh

    2016-06-01

    Full Text Available Performance and emission characteristics of HCCI engines depend on achieving a good in-cylinder homogeneous mixture. The formation of in-cylinder mixture depends on many engine parameters, which need optimization. In addition, as of now, there is no direct way to clearly describe and estimate in-cylinder mixture homogeneity. In the CFD analysis, it is evaluated indirectly using contour plots of equivalence ratio, variation of in-cylinder pressure with crank angles, heat release curves or by the comparison of emissions. In this study, an attempt has been made to develop methods to evaluate the in-cylinder mixture homogeneity by the CFD analysis using AVL-FIRE. Here, global and local in-cylinder fuel distribution and in-cylinder fuel distribution index are used to evaluate the mixture homogeneity. In order to evaluate these methods, mixture homogeneities in two cases of fuel injections with 7- and 10-hole injector are compared. Finally, we found that the global fuel distribution (GFD plot helps direct quantitative assessment of mixture distribution in various ER range. However, the GFD method cannot explain the spatial variation of fuel distribution and does not provide mixture homogeneity on a simple scale. In the method of plotting fuel distribution index, the overall homogeneity will be evaluated on a scale of 0 to 1 by a simple way. In the method of plotting local fuel distribution (LFD, the spatial variation of mixture homogeneity is well defined in local zones both in radial and axial directions. Further, these proposed methods help us to reduce the computation time significantly.

  11. Turbulent combustion

    Energy Technology Data Exchange (ETDEWEB)

    Talbot, L.; Cheng, R.K. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    Turbulent combustion is the dominant process in heat and power generating systems. Its most significant aspect is to enhance the burning rate and volumetric power density. Turbulent mixing, however, also influences the chemical rates and has a direct effect on the formation of pollutants, flame ignition and extinction. Therefore, research and development of modern combustion systems for power generation, waste incineration and material synthesis must rely on a fundamental understanding of the physical effect of turbulence on combustion to develop theoretical models that can be used as design tools. The overall objective of this program is to investigate, primarily experimentally, the interaction and coupling between turbulence and combustion. These processes are complex and are characterized by scalar and velocity fluctuations with time and length scales spanning several orders of magnitude. They are also influenced by the so-called {open_quotes}field{close_quotes} effects associated with the characteristics of the flow and burner geometries. The authors` approach is to gain a fundamental understanding by investigating idealized laboratory flames. Laboratory flames are amenable to detailed interrogation by laser diagnostics and their flow geometries are chosen to simplify numerical modeling and simulations and to facilitate comparison between experiments and theory.

  12. A Chemical Kinetic Model of PRF Oxidation for HCCI Engine Ⅱ: Structure of a skeletal model%适用于HCCI发动机的基础燃料化学动力学模型Ⅱ:构造骨架机理

    Institute of Scientific and Technical Information of China (English)

    张庆峰; 郑朝蕾; 何祖威; 王迎

    2011-01-01

    提出了一个适用于HCCI发动机燃烧过程研究的基础燃料骨架机理模型,包含42种物质和71个反应.骨架机理分别对不同基础燃料(PRF0、PRF60、PRF80、PRF90和PRF100)在温度为667~1 350 K下进行了着火延迟期的预测计算,与试验结果的对比是较为吻合的.HCCI发动机试验的验证表明,无论是配比的基础燃料(PRF70、PRF91.8),还是单组分燃料(PRF100),该机理对缸内燃烧及排放情况的预测均是令人满意的.由此可知,该骨架机理在HCCI燃烧方面的预测性能是可靠的,可以应用于HCCI发动机的多维模拟.敏感性分析表明,针对PRF70与PRF91.8燃料HCCI工况下的燃烧情况,异辛烷与氧气的脱氢反应和正庚烷与羟基的氧化反应对缸内着火的影响较大,CH2O、CH3是非常重要的中间自由基.%A skeletal chemical kinetic mechanism including 42 species and 71 reactions for the oxidation of primary reference fuels (PRF) was proposed and applied to simulate homogeneous charge compression ignition (HCCI) combustion. The ignition delay predicted by the skeletal mechanism was validated with experiments. Validated results show good agreements for the PRF0, PRF60, PRF80, PRF90, PRF100 fuels over temperatures in the range of 667 K to 1 350 K. Validation of the present PRF mechanism was also performed with experiments from HCCI engines available in the literature, and good agreement was obtained for the PRF70, PRF91.8, PRF100 fuels. Results show that this PRF mechanism gives reliable performance for HCCI combustion predictions. The present PRF mechanism can be applied to multi-dimensional CFD simulations. Sensitivity analysis indicates that for PRF70 and PRF91.8 fuels under HCCI conditions, Hatom abstraction from iso-octane molecule reaction and OH addition to n-heptane molecule have large influence, and CH2O, CH3 are very important intermediate species.

  13. RBCC发动机亚燃模态一次火箭引导燃烧的实验%Experiment of primary rocket-piloting combustion under ramjet-mode condition in RBCC

    Institute of Scientific and Technical Information of China (English)

    徐朝启; 何国强; 刘佩进; 秦飞; 潘科玮

    2013-01-01

    The experimental studies were performed to investigate primary rocket piloting liquid kerosene (JP-10) combustion in rocket-based combined cycle (RBCC) combustor under typical ramjet-mode condition. Due to the low total temperature of incoming airflow in ramjet mode, the primary rocket with relative low mass flowrate was employed as a piloting flame to achieve reliable ignition and stabilized combustion of liquid kerosene (JP-10) in RBCC combustor. The secondary fuel (JP-10) has been injected into airflow by two strut injectors located behind the primary rocket and an upstream cavity flush-wall injector. The effects of cavity and the location position of strut and wall injection have been investigated. . The strut injectors make the fuel easily be distributed into main airflow, and the results indicate that the injected fuel can accomplish steady and efficient combustion due to the interaction with the rocket plume. The comparisons of the pressure distributions in the combustor under different injection conditions show that the strut injection plays an important role in the combustion of wall injection fuel, and additional wall injection associated with cavity would improve the performance of RBCC combustor. Moreover, the wall injection location and the distance between the wall injection and cavity need to be further considered to obtain optimal engine performance.%针对使用液体煤油燃料(JP-10)的火箭基组合动力循环(RBCC)发动机在亚燃模态下使用一次火箭作为引导的燃烧组织开展了实验研究.实验在低来流总温条件下,使用小流量一次火箭羽流作为引导火焰可以实现液体煤油的可靠点火和稳定燃烧,并在扩张燃烧室中实现“热力壅塞”,从而完成RBCC发动机亚燃模态的高效燃烧.在目前发动机燃烧室构型下,通过一系列的发动机壁面压力分布曲线和推力增益的比较,研究了凹腔,支板及壁面喷注位置对发动机性能的影响.实验的结果

  14. [Chemiluminescence spectroscopic analysis of homogeneous charge compression ignition combustion processes].

    Science.gov (United States)

    Liu, Hai-feng; Yao, Ming-fa; Jin, Chao; Zhang, Peng; Li, Zhe-ming; Zheng, Zun-qing

    2010-10-01

    To study the combustion reaction kinetics of homogeneous charge compression ignition (HCCI) under different port injection strategies and intake temperature conditions, the tests were carried out on a modified single-cylinder optical engine using chemiluminescence spectroscopic analysis. The experimental conditions are keeping the fuel mass constant; fueling the n-heptane; controlling speed at 600 r x min(-1) and inlet pressure at 0.1 MPa; controlling inlet temperature at 95 degrees C and 125 degrees C, respectively. The results of chemiluminescence spectrum show that the chemiluminescence is quite faint during low temperature heat release (LTHR), and these bands spectrum originates from formaldehyde (CH2O) chemiluminescence. During the phase of later LTHR-negative temperature coefficient (NTC)-early high temperature heat release (HTHR), these bands spectrum also originates from formaldehyde (CH2O) chemiluminescence. The CO--O* continuum is strong during HTHR, and radicals such as OH, HCO, CH and CH2O appear superimposed on this CO--O* continuum. After the HTHR, the chemiluminescence intensity is quite faint. In comparison to the start of injection (SOI) of -30 degrees ATDC, the chemiluminescence intensity is higher under the SOI = -300 degrees ATDC condition due to the more intense emissions of CO--O* continuum. And more radicals of HCO and OH are formed, which also indicates a more intense combustion reaction. Similarly, more intense CO--O* continuum and more radicals of HCO and OH are emitted under higher intake temperature case.

  15. Advanced Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, Gordon R. [NETL

    2013-03-11

    The activity reported in this presentation is to provide the mechanical and physical property information needed to allow rational design, development and/or choice of alloys, manufacturing approaches, and environmental exposure and component life models to enable oxy-fuel combustion boilers to operate at Ultra-Supercritical (up to 650{degrees}C & between 22-30 MPa) and/or Advanced Ultra-Supercritical conditions (760{degrees}C & 35 MPa).

  16. Autoignition characterization of primary reference fuels and n-heptane/n-butanol mixtures in a constant volume combustion device and homogeneous charge compression ignition engine

    KAUST Repository

    Baumgardner, Marc E.

    2013-12-19

    In this study, the autoignition behavior of primary reference fuels (PRF) and blends of n-heptane/n-butanol were examined in a Waukesha Fuel Ignition Tester (FIT) and a Homogeneous Charge Compression Engine (HCCI). Fourteen different blends of iso-octane, n-heptane, and n-butanol were tested in the FIT - 28 test runs with 25 ignition measurements for each test run, totaling 350 individual tests in all. These experimental results supported previous findings that fuel blends with high alcohol content can exhibit very different ignition delay periods than similarly blended reference fuels. The experiments further showed that n-butanol blends behaved unlike PRF blends when comparing the autoignition behavior as a function of the percentage of low reactivity component. The HCCI and FIT experimental results favorably compared against single and multizone models with detailed chemical kinetic mechanisms - both an existing mechanism as well as one developed during this study were used. The experimental and modeling results suggest that that the FIT instrument is a valuable tool for analysis of high pressure, low temperature chemistry, and autoignition for future fuels in advanced combustion engines. Additionally, in both the FIT and engine experiments the fraction of low temperature heat release (fLTHR) was found to correlate very well with the crank angle of maximum heat release and shows promise as a useful metric for fuel reactivity in advanced combustion applications. © 2013 American Chemical Society.

  17. Development of a Premixed Combustion Capability for Scramjet Combustion Experiments

    Science.gov (United States)

    Rockwell, Robert D.; Goyne, Christopher P.; Rice, Brian E.; Chelliah, Harsha; McDaniel, James C.; Edwards, Jack R.; Cantu, Luca M. L.; Gallo, Emanuela C. A.; Cutler, Andrew D.; Danehy, Paul M.

    2015-01-01

    Hypersonic air-breathing engines rely on scramjet combustion processes, which involve high speed, compressible, and highly turbulent flows. The combustion environment and the turbulent flames at the heart of these engines are difficult to simulate and study in the laboratory under well controlled conditions. Typically, wind-tunnel testing is performed that more closely approximates engine testing rather than a careful investigation of the underlying physics that drives the combustion process. The experiments described in this paper, along with companion data sets being developed separately, aim to isolate the chemical kinetic effects from the fuel-air mixing process in a dual-mode scramjet combustion environment. A unique fuel injection approach is taken that produces a nearly uniform fuel-air mixture at the entrance to the combustor. This approach relies on the precombustion shock train upstream of the dual-mode scramjet combustor. A stable ethylene flame anchored on a cavity flameholder with a uniformly mixed combustor inflow has been achieved in these experiments allowing numerous companion studies involving coherent anti-Stokes Raman scattering (CARS), particle image velocimetry (PIV), and planar laser induced fluorescence (PLIF) to be performed.

  18. Sound quality assessment of Diesel combustion noise using in-cylinder pressure components

    Science.gov (United States)

    Payri, F.; Broatch, A.; Margot, X.; Monelletta, L.

    2009-01-01

    The combustion process in direct injection (DI) Diesel engines is an important source of noise, and it is thus the main reason why end-users could be reluctant to drive vehicles powered with this type of engine. This means that the great potential of Diesel engines for environment preservation—due to their lower consumption and the subsequent reduction of CO2 emissions—may be lost. Moreover, the advanced combustion concepts—e.g. the HCCI (homogeneous charge compression ignition)—developed to comply with forthcoming emissions legislation, while maintaining the efficiency of current engines, are expected to be noisier because they are characterized by a higher amount of premixed combustion. For this reason many efforts have been dedicated by car manufacturers in recent years to reduce the overall level and improve the sound quality of engine noise. Evaluation procedures are required, both for noise levels and sound quality, that may be integrated in the global engine development process in a timely and cost-effective manner. In previous published work, the authors proposed a novel method for the assessment of engine noise level. A similar procedure is applied in this paper to demonstrate the suitability of combustion indicators for the evaluation of engine noise quality. These indicators, which are representative of the peak velocity of fuel burning and the resonance in the combustion chamber, are well correlated with the combustion noise mark obtained from jury testing. Quite good accuracy in the prediction of the engine noise quality has been obtained with the definition of a two-component regression, which also permits the identification of the combustion process features related to the resulting noise quality, so that corrective actions may be proposed.

  19. Combustion Research Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Combustion Research Laboratory facilitates the development of new combustion systems or improves the operation of existing systems to meet the Army's mission for...

  20. High Combustion Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — At NETL's High-Pressure Combustion Research Facility in Morgantown, WV, researchers can investigate new high-pressure, high-temperature hydrogen turbine combustion...

  1. Comparison of Single-zone and Multi-zone Combustion Model for HCCI Engine%均质压燃(HCCI)单区和多区燃烧模型的比较

    Institute of Scientific and Technical Information of China (English)

    钟绍华; 孔斌; Miroslaw Lech Wyszynski; Xu Hong-ming

    2007-01-01

    利用耦合化学动力学软件包CHEMKIN建立了汽油HCCI发动机的单区和多区燃烧模型.与试验数据的对比表明:虽然单区模型在参数化研究中能较准确地预测混合气的自燃定时,但其准确性在很大程度上取决于缸内的均匀性;包含缝隙区、淬熄区、质量交换区和绝热核心区的九区燃烧模型通过设置特定的功能分区能更好地模拟HCCI的燃烧过程,它在对自燃定时的预测和对热量释放过程和排放物的形成机理的模拟等方面都有很好的性能.

  2. Natural Gas HCCI Combustion When Engine Operating with Negative Valve Overlap%负气门叠开方式下天然气的均质压燃(HCCI)

    Institute of Scientific and Technical Information of China (English)

    钟绍华; Miroslaw Lech Wyszynski; Yap Daniel

    2007-01-01

    天然气的自燃温度较高,要达到其自燃必须采用高压缩比和进气加热,另外一种方法是利用负气门叠开在缸内驻留废气,以减少所需要的进气加热量.本文采用特殊阀的策略,通过与汽油进行对比,发现在相同的发动机负荷下,天然气HCCI需要使用较迟后的气门定时,这导致缸内将截获较少量的废气,因而减小了稀释的效果,使得NOx的排放增加.

  3. Effects of Exhaust Gas Recirculation on the Homogeneous Charge Combustion Process of n-Heptane at Different Load Conditions

    Institute of Scientific and Technical Information of China (English)

    LIU Dexin; FENG Hongqing; ZHENG Jincai; MILLER David L; CERNANSKY Nicholas P

    2005-01-01

    Effects of exhaust gas recirculation (EGR) on homogeneous charge combustion of n-heptane was studied through simulation and experiment. Experiments were carried out in a single cylinder, four-stroke, air cooled engine and a single cylinder, two-stroke, water cooled engine. In the four-stroke engine, experiments of the effects of EGR were examined using heated N2 addition as a surrogate for external EGR and modifying engine to increase internal EGR. The ignition timing was sensitive to EGR due to thermal and chemical effects. EGR or extra air is a key factor in eliminating knock during mid-load conditions. For higher load operation the only way to avoid knock is to control reaction timing through the use of spark ignition. Experimental and modeling results from the two-stroke engine show that auto-ignition can be avoided by increasing the engine speed. The two-stroke engine experiments indicate that high levels of internal EGR can enable spark ignition at lean conditions. At higher load conditions, increasing the engine speed is an effective method to control transition from homogeneous charge compression ignition (HCCI) operation to non-HCCI operation and successful spark ignition of a highly dilute mixture can avoid serious knock.

  4. Combustion synthesis of advanced composite materials

    Science.gov (United States)

    Moore, John J.

    1993-01-01

    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product morphology and properties. The use of an in situ liquid infiltration technique and the effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e., solids, liquids and gases, with varying physical properties e.g., volatility and thermal conductivity, on the microstructure and morphology of synthesized composite materials is discussed. Conducting the combustion synthesis reaction in a reactive gas environment to take advantage of the synergistic effects of combustion synthesis and vapor phase transport is also examined.

  5. Distributed Low Temperature Combustion: Fundamental Understanding of Combustion Regime Transitions

    Science.gov (United States)

    2016-09-07

    Excellent optical access for laser- based diagnostic measurements ; (ii) Accurate experimental control of boundary conditions; (iii) Aerodynamic flame...potential to extend methods based on bimodal approximations, such as the BML [21] framework , by permitting inter- mediate fluid states, which is of...identify the impact of the major chemical pathways on combustion mode transitions. The conceptual multifluid approach of Spalding can be used to avoid

  6. Combustion chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Brown, N.J. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

  7. The Approaches to Expanding the Operating Range of HCCI Engine%拓宽HCCI发动机运行区域的方法探讨

    Institute of Scientific and Technical Information of China (English)

    邹健; 王谦; 刘春生

    2007-01-01

    均质充量压缩燃烧(HCCI)技术由于其较高的燃油经济性和极低的NOx及PM排放越来越受到重视,但是由于HCCI 模式发动机运行区域狭小,限制了其在实际中的应用.对限制HCCI发动机运行区域的因素进行了分析,并研究讨论了拓宽HCCI模式运行区域的方法,包括使用进气增压、提高压缩比、使用混合燃料和废气再循环(EGR)等,能在一定程度上拓宽HCCI发动机在高负荷或低负荷时的运行区域,使HCCI 燃烧技术能在发动机高负荷和低负荷的工况下适用.

  8. The development and experimental validation of a reduced ternary kinetic mechanism for the auto-ignition at HCCI conditions, proposing a global reaction path for ternary gasoline surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Machrafi, Hatim; Cavadias, Simeon; Amouroux, Jacques [UPMC Universite Paris 06, LGPPTS, Ecole Nationale Superieure de Chimie de Paris, 11, rue de Pierre et Marie Curie, 75005 Paris (France)

    2009-02-15

    To acquire a high amount of information of the behaviour of the Homogeneous Charge Compression Ignition (HCCI) auto-ignition process, a reduced surrogate mechanism has been composed out of reduced n-heptane, iso-octane and toluene mechanisms, containing 62 reactions and 49 species. This mechanism has been validated numerically in a 0D HCCI engine code against more detailed mechanisms (inlet temperature varying from 290 to 500 K, the equivalence ratio from 0.2 to 0.7 and the compression ratio from 8 to 18) and experimentally against experimental shock tube and rapid compression machine data from the literature at pressures between 9 and 55 bar and temperatures between 700 and 1400 K for several fuels: the pure compounds n-heptane, iso-octane and toluene as well as binary and ternary mixtures of these compounds. For this validation, stoichiometric mixtures and mixtures with an equivalence ratio of 0.5 are used. The experimental validation is extended by comparing the surrogate mechanism to experimental data from an HCCI engine. A global reaction pathway is proposed for the auto-ignition of a surrogate gasoline, using the surrogate mechanism, in order to show the interactions that the three compounds can have with one another during the auto-ignition of a ternary mixture. (author)

  9. Oxygen-enhanced combustion

    CERN Document Server

    Baukal, Charles E

    2013-01-01

    Combustion technology has traditionally been dominated by air/fuel combustion. However, two developments have increased the significance of oxygen-enhanced combustion-new technologies that produce oxygen less expensively and the increased importance of environmental regulations. Advantages of oxygen-enhanced combustion include less pollutant emissions as well as increased energy efficiency and productivity. Oxygen-Enhanced Combustion, Second Edition compiles information about using oxygen to enhance industrial heating and melting processes. It integrates fundamental principles, applications, a

  10. Effects of Injection Timing on Fluid Flow Characteristics of Partially Premixed Combustion Based on High-Speed Particle Image Velocimetry

    KAUST Repository

    Izadi Najafabadi, Mohammad

    2017-03-28

    Partially Premixed Combustion (PPC) is a promising combustion concept ,based on judicious tuning of the charge stratification, to meet the increasing demands of emission legislation and to improve fuel efficiency. Longer ignition delays of PPC in comparison with conventional diesel combustion provide better fuel/air mixture which decreases soot and NO emissions. Moreover, a proper injection timing and strategy for PPC can improve the combustion stability as a result of a higher level of fuel stratification in comparison with the Homogeneous Charge Compression Ignition (HCCI) concept. Injection timing is the major parameter with which to affect the level of fuel and combustion stratification and to control the combustion phasing and the heat release behavior. The scope of the present study is to investigate the fluid flow characteristics of PPC at different injection timings. To this end, high-speed Particle Image Velocimetry (PIV) is implemented in a light-duty optical engine to measure fluid flow characteristics, including the flow fields, mean velocity and cycle-resolved turbulence, inside the piston bowl as well as the squish region with a temporal resolution of 1 crank angle degree at 800 rpm. Two injectors, having 5 and 7 holes, were compared to see their effects on fluid flow and heat release behavior for different injection timings. Reactive and non-reactive measurements were performed to distinguish injection-driven and combustion-driven turbulence. Formation of vortices and higher turbulence levels enhance the air/fuel interaction, changing the level of fuel stratification and combustion duration. Results demonstrate clearly how turbulence level correlates with heat release behavior, and provide a quantitative dataset for validation of numerical simulations.

  11. On the stability of slow neutron combustion in astrophysical objects

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, J.E.; Benvenuto, O.G.

    1988-11-03

    The problem of slow neutron combustion in astrophysical objects is studied from the hydrodynamical point of view, showing that unless the existence of unknown stabilizing effects, the process seems to be absolutely unstable. It is shown that the slow combustion is likely to become a fast combustion mode called detonation. Some possible consequences of this instability for neutron stars and type II supernovae are presented and discussed.

  12. Liquid rocket combustion chamber acoustic characterization

    Directory of Open Access Journals (Sweden)

    Cândido Magno de Souza

    2010-09-01

    Full Text Available Over the last 40 years, many solid and liquid rocket motors have experienced combustion instabilities. Among other causes, there is the interaction of acoustic modes with the combustion and/or fluid dynamic processes inside the combustion chamber. Studies have been showing that, even if less than 1% of the available energy is diverted to an acoustic mode, combustion instability can be generated. On one hand, this instability can lead to ballistic pressure changes, couple with other propulsion systems such as guidance or thrust vector control, and in the worst case, cause motor structural failure. In this case, measures, applying acoustic techniques, must be taken to correct/minimize these influences on the combustion. The combustion chamber acoustic behavior in operating conditions can be estimated by considering its behavior in room conditions. In this way, acoustic tests can be easily performed, thus identifying the cavity modes. This paper describes the procedures to characterize the acoustic behavior in the inner cavity of four different configurations of a combustion chamber. Simple analytical models are used to calculate the acoustic resonance frequencies and these results are compared with acoustic natural frequencies measured at room conditions. Some comments about the measurement procedures are done, as well as the next steps for the continuity of this research. The analytical and experimental procedures results showed good agreement. However, limitations on high frequency band as well as in the identification of specific kinds of modes indicate that numerical methods able to model the real cavity geometry and an acoustic experimental modal analysis may be necessary for a more complete analysis. Future works shall also consider the presence of passive acoustic devices such as baffles and resonators capable of introducing damping and avoiding or limiting acoustic instabilities.

  13. Combustion 2000

    Energy Technology Data Exchange (ETDEWEB)

    A. Levasseur; S. Goodstine; J. Ruby; M. Nawaz; C. Senior; F. Robson; S. Lehman; W. Blecher; W. Fugard; A. Rao; A. Sarofim; P. Smith; D. Pershing; E. Eddings; M. Cremer; J. Hurley; G. Weber; M. Jones; M. Collings; D. Hajicek; A. Henderson; P. Klevan; D. Seery; B. Knight; R. Lessard; J. Sangiovanni; A. Dennis; C. Bird; W. Sutton; N. Bornstein; F. Cogswell; C. Randino; S. Gale; Mike Heap

    2001-06-30

    . To achieve these objectives requires a change from complete reliance of coal-fired systems on steam turbines (Rankine cycles) and moving forward to a combined cycle utilizing gas turbines (Brayton cycles) which offer the possibility of significantly greater efficiency. This is because gas turbine cycles operate at temperatures well beyond current steam cycles, allowing the working fluid (air) temperature to more closely approach that of the major energy source, the combustion of coal. In fact, a good figure of merit for a HIPPS design is just how much of the enthalpy from coal combustion is used by the gas turbine. The efficiency of a power cycle varies directly with the temperature of the working fluid and for contemporary gas turbines the optimal turbine inlet temperature is in the range of 2300-2500 F (1260-1371 C). These temperatures are beyond the working range of currently available alloys and are also in the range of the ash fusion temperature of most coals. These two sets of physical properties combine to produce the major engineering challenges for a HIPPS design. The UTRC team developed a design hierarchy to impose more rigor in our approach. Once the size of the plant had been determined by the choice of gas turbine and the matching steam turbine, the design process of the High Temperature Advanced Furnace (HITAF) moved ineluctably to a down-fired, slagging configuration. This design was based on two air heaters: one a high temperature slagging Radiative Air Heater (RAH) and a lower temperature, dry ash Convective Air Heater (CAH). The specific details of the air heaters are arrived at by an iterative sequence in the following order:-Starting from the overall Cycle requirements which set the limits for the combustion and heat transfer analysis-The available enthalpy determined the range of materials, ceramics or alloys, which could tolerate the temperatures-Structural Analysis of the designs proved to be the major limitation-Finally the commercialization

  14. Combustion 2000

    Energy Technology Data Exchange (ETDEWEB)

    A. Levasseur; S. Goodstine; J. Ruby; M. Nawaz; C. Senior; F. Robson; S. Lehman; W. Blecher; W. Fugard; A. Rao; A. Sarofim; P. Smith; D. Pershing; E. Eddings; M. Cremer; J. Hurley; G. Weber; M. Jones; M. Collings; D. Hajicek; A. Henderson; P. Klevan; D. Seery; B. Knight; R. Lessard; J. Sangiovanni; A. Dennis; C. Bird; W. Sutton; N. Bornstein; F. Cogswell; C. Randino; S. Gale; Mike Heap

    2001-06-30

    . To achieve these objectives requires a change from complete reliance of coal-fired systems on steam turbines (Rankine cycles) and moving forward to a combined cycle utilizing gas turbines (Brayton cycles) which offer the possibility of significantly greater efficiency. This is because gas turbine cycles operate at temperatures well beyond current steam cycles, allowing the working fluid (air) temperature to more closely approach that of the major energy source, the combustion of coal. In fact, a good figure of merit for a HIPPS design is just how much of the enthalpy from coal combustion is used by the gas turbine. The efficiency of a power cycle varies directly with the temperature of the working fluid and for contemporary gas turbines the optimal turbine inlet temperature is in the range of 2300-2500 F (1260-1371 C). These temperatures are beyond the working range of currently available alloys and are also in the range of the ash fusion temperature of most coals. These two sets of physical properties combine to produce the major engineering challenges for a HIPPS design. The UTRC team developed a design hierarchy to impose more rigor in our approach. Once the size of the plant had been determined by the choice of gas turbine and the matching steam turbine, the design process of the High Temperature Advanced Furnace (HITAF) moved ineluctably to a down-fired, slagging configuration. This design was based on two air heaters: one a high temperature slagging Radiative Air Heater (RAH) and a lower temperature, dry ash Convective Air Heater (CAH). The specific details of the air heaters are arrived at by an iterative sequence in the following order:-Starting from the overall Cycle requirements which set the limits for the combustion and heat transfer analysis-The available enthalpy determined the range of materials, ceramics or alloys, which could tolerate the temperatures-Structural Analysis of the designs proved to be the major limitation-Finally the commercialization

  15. Experimental study of hydrogen as a fuel additive in internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Saanum, Inge

    2008-07-01

    . % hydrogen to the methane, but 5 vol. % hydrogen also resulted in a noticeable increase. The flame structure was also influenced by the hydrogen addition as the flame front had a higher tendency to become wrinkled or cellular. The effect is believed to mainly be caused by a reduction in the effective Lewis number of the mixture. In the gas engine experiments, the effect of adding 25 vol. % hydrogen to natural gas was investigated when the engine was run on lean air/fuel mixtures and on stoichiometric mixtures with exhaust gas recirculation. The hydrogen addition was found to extend the lean limit of stable combustion and hence caused lower NO{sub x} emissions. The brake thermal efficiency increased with the hydrogen addition, both for the fuel lean and the stoichiometric mixtures with exhaust gas recirculation. This is mainly because of shorter combustion durations when the hydrogen mixture was used, leading to thermodynamically improved cycles. Two types of experiments were performed in compression ignition engines. First, homogenous charge compression ignition (HCCI) experiments were performed in a single cylinder engine fueled with natural gas and diesel oil. As HCCI engines have high thermal efficiency and low NO{sub x} and PM emissions it may be more favorable to use natural gas in HCCI engines than in spark ignition engines. The mixture of natural gas, diesel oil and air was partly premixed before combustion. The natural gas/diesel ratio was used to control the ignition timing as the fuels have very different ignition properties. The natural gas was also replaced by a 20 vol. % hydrogen/natural gas mixture to study the effect of hydrogen on the ignition and combustion process. Also, rape seed methyl ester (RME) was tested instead of the diesel oil. The combustion phasing was found to mainly be controlled by the amount of liquid fuel injected. The last experiments with compression ignition were performed by using a standard Scania diesel engine where the possibilities

  16. Experimental study of hydrogen as a fuel additive in internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Saanum, Inge

    2008-07-01

    . % hydrogen to the methane, but 5 vol. % hydrogen also resulted in a noticeable increase. The flame structure was also influenced by the hydrogen addition as the flame front had a higher tendency to become wrinkled or cellular. The effect is believed to mainly be caused by a reduction in the effective Lewis number of the mixture. In the gas engine experiments, the effect of adding 25 vol. % hydrogen to natural gas was investigated when the engine was run on lean air/fuel mixtures and on stoichiometric mixtures with exhaust gas recirculation. The hydrogen addition was found to extend the lean limit of stable combustion and hence caused lower NO{sub x} emissions. The brake thermal efficiency increased with the hydrogen addition, both for the fuel lean and the stoichiometric mixtures with exhaust gas recirculation. This is mainly because of shorter combustion durations when the hydrogen mixture was used, leading to thermodynamically improved cycles. Two types of experiments were performed in compression ignition engines. First, homogenous charge compression ignition (HCCI) experiments were performed in a single cylinder engine fueled with natural gas and diesel oil. As HCCI engines have high thermal efficiency and low NO{sub x} and PM emissions it may be more favorable to use natural gas in HCCI engines than in spark ignition engines. The mixture of natural gas, diesel oil and air was partly premixed before combustion. The natural gas/diesel ratio was used to control the ignition timing as the fuels have very different ignition properties. The natural gas was also replaced by a 20 vol. % hydrogen/natural gas mixture to study the effect of hydrogen on the ignition and combustion process. Also, rape seed methyl ester (RME) was tested instead of the diesel oil. The combustion phasing was found to mainly be controlled by the amount of liquid fuel injected. The last experiments with compression ignition were performed by using a standard Scania diesel engine where the possibilities

  17. On supersonic combustion

    Institute of Scientific and Technical Information of China (English)

    袁生学

    1999-01-01

    Some basic concepts and features of supersonic combustion are explained from the view point of macroscopic aerodynamics. Two kinds of interpretations of supersonic combustion are proposed. The difference between supersonic combustion and subsonic combustion is discussed, and the mechanism of supersonic combustion propagation and the limitation of heat addition in supersonic flow are pointed out. The results of the calculation of deflagration in supersonic flow show that the entropy increment and the total pressure loss of the combustion products may decrease with the increase of combustion velocity. It is also demonstrated that the oblique detonation wave angle may not be controlled by the wedge angle under weak underdriven solution conditions and be determined only by combustion velocity. Therefore, the weak underdriven solution may become self-sustaining oblique detonation waves with a constant wave angle.

  18. Combustion Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — For more than 30 years The Combustion Research Facility (CRF) has served as a national and international leader in combustion science and technology. The need for a...

  19. Towards a detailed soot model for internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Mosbach, Sebastian; Celnik, Matthew S.; Raj, Abhijeet; Kraft, Markus [Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA (United Kingdom); Zhang, Hongzhi R. [Department of Chemical Engineering, University of Utah, 1495 East 100 South, Kennecott Research Building, Salt Lake City, UT 84112 (United States); Kubo, Shuichi [Frontier Research Center, Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan); Kim, Kyoung-Oh [Higashifuji Technical Center, Toyota Motor Corporation, Mishuku 1200, Susono, Shizuoka 480-1193 (Japan)

    2009-06-15

    In this work, we present a detailed model for the formation of soot in internal combustion engines describing not only bulk quantities such as soot mass, number density, volume fraction, and surface area but also the morphology and chemical composition of soot aggregates. The new model is based on the Stochastic Reactor Model (SRM) engine code, which uses detailed chemistry and takes into account convective heat transfer and turbulent mixing, and the soot formation is accounted for by SWEEP, a population balance solver based on a Monte Carlo method. In order to couple the gas-phase to the particulate phase, a detailed chemical kinetic mechanism describing the combustion of Primary Reference Fuels (PRFs) is extended to include small Polycyclic Aromatic Hydrocarbons (PAHs) such as pyrene, which function as soot precursor species for particle inception in the soot model. Apart from providing averaged quantities as functions of crank angle like soot mass, volume fraction, aggregate diameter, and the number of primary particles per aggregate for example, the integrated model also gives detailed information such as aggregate and primary particle size distribution functions. In addition, specifics about aggregate structure and composition, including C/H ratio and PAH ring count distributions, and images similar to those produced with Transmission Electron Microscopes (TEMs), can be obtained. The new model is applied to simulate an n-heptane fuelled Homogeneous Charge Compression Ignition (HCCI) engine which is operated at an equivalence ratio of 1.93. In-cylinder pressure and heat release predictions show satisfactory agreement with measurements. Furthermore, simulated aggregate size distributions as well as their time evolution are found to qualitatively agree with those obtained experimentally through snatch sampling. It is also observed both in the experiment as well as in the simulation that aggregates in the trapped residual gases play a vital role in the soot

  20. Towards a detailed soot model for internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Kraft, Markus; Mosbach, Sebastian; Celnik, Matthew S. [Univ. of Cambridge (United Kingdom); Zhang, Hongzhi R. [Univ. of Utah (United States); Kubo, Shuichi; Kim, Kyoung-Oh [Toyota (Japan)

    2008-07-01

    In this work, we integrate previously developed models for engine combustion and soot formation. Namely, we combine the stochastic reactor model (SRM) engine code, which uses detailed chemistry and takes into account convective heat transfer and turbulent mixing, with SWEEP, a population balance solver based on a Monte Carlo method. In order to couple the two codes, a detailed chemical kinetic mechanism describing the combustion of primary reference fuels (PRFs) is extended to include small Polycyclic Aromatic Hydrocarbons (PAHs) such as pyrene, which function as soot precursor species for particle inception in the soot model. The integrated model provides not only averaged quantities as functions of crank angle like soot mass, volume fraction, aggregate diameter, and the number of primary particles per aggregate for example, but also more detailed information such as aggregate and primary particle size distribution functions. In addition, specifics about aggregate structure and composition, including C/H ratio and PAH ring count distributions, and images similar to those produced with transmission electron microscopes (TEMs), can be obtained. The combined model is applied to simulate an n-heptane fuelled homogeneous charge compression ignition (HCCI) engine which is operated at an equivalence ratio of 1.93. In-cylinder pressure and heat release predictions show satisfactory agreement with measurements. Furthermore, simulated aggregate size distributions as well as their time evolution are found to qualitatively agree with those obtained experimentally through snatch sampling. It is also seen both in the experiment as well as in the simulation that aggregates in the trapped residual gases play a vital role in the soot formation process. (orig.)

  1. Process for Operating a Dual-Mode Combustor

    Science.gov (United States)

    Trefny, Charles J. (Inventor); Dippold, Vance F. (Inventor)

    2017-01-01

    A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

  2. Effective reduction of in-cylinder peak pressures in Homogeneous Charge Compression Ignition Engine – A computational study

    Directory of Open Access Journals (Sweden)

    T. Karthikeya Sharma

    2015-09-01

    Full Text Available HCCI mode of combustion is known for simultaneous reduction of NOx and PM emissions besides yielding low specific fuel consumption. The nature of volumetric combustion of HCCI engine leads to the development of high peak pressures inside the combustion chamber. This high peak pressures may damage the engine, limiting the HCCI engine life period and thus demands sturdy designs. In this study an attempt is made to analyze computationally the effect of induction swirl in reducing the peak pressures of a HCCI engine under various operating parameters. For the study, specifications of a single cylinder 1.6 L, reentrant piston bowl diesel engine are chosen. For the computational analysis ECFM-3Z model of STARCD is considered. This model is suitable to analyze the combustion processes in SI and CI engines. As HCCI engine is a hybrid version of SI and CI engines, ECFM-3Z model with necessary modifications is used to analyze the peak pressures inside the combustion chamber. The ECFM-3Z model for HCCI mode of combustion is validated with the existing literature to make sure that the results obtaining are accurate. Numerical experiments are performed to study the effect of compression ratio, equivalence ratio, exhaust gas recirculation and boost pressure under different swirl ratios in reducing the in-cylinder peak pressures. The results showed that swirl ratio has a considerable impact in limiting the peak pressures of HCCI engine. The analysis resulted in achieving about 21% reduction in peak pressures are achieved when a swirl ratio of 4 with 30% EGR is adopted when compared to a swirl ratio of 1 with 0% EGR. The study revealed that out of the four operating parameters selected, lower compression ratios, higher EGR concentrations, lower equivalence ratios, lower boost pressures and higher swirl ratios are favorable in reducing the peak pressures.

  3. Computational Study on Homogeneous Charge Compression Ignition of Diesel Fuel%柴油均质压燃燃烧(HCCI)的计算模拟研究

    Institute of Scientific and Technical Information of China (English)

    王宇宾; 邓康耀; 崔毅

    2004-01-01

    通过可模拟均质压燃燃烧(HCCI)的计算程序分析了进气温度、压缩比、过量空气系数、EGR率等参数对柴油机HCCI的影响,同时确定HCCI可行的工况范围.计算所得出的HCCI可行范围和优化工况对相应燃烧试验具有指导作用.

  4. Nonlinear theory of combustion stability in liquid rocket engine based on chemistry dynamics

    Institute of Scientific and Technical Information of China (English)

    黄玉辉; 王振国; 周进

    2002-01-01

    Detailed models of combustion instability based on chemistry dynamics are developed. The results show that large activation energy goes against the combustion stability. The heat transfer coefficient between the wall and the combust gas is an important bifurcation parameter for the combustion instability. The acoustics modes of the chamber are in competition and cooperation with each other for limited vibration energy. Thermodynamics criterion of combustion stability can be deduced from the nonlinear thermodynamics. Correlations of the theoretical results and historical experiments indicate that chemical kinetics play a critical role in the combustion instability.

  5. Pulsed atmospheric fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  6. Low Temperature Combustion Demonstrator for High Efficiency Clean Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Ojeda, William de

    2010-07-31

    The project which extended from November 2005 to May of 2010 demonstrated the application of Low Temperature Combustion (LTC) with engine out NOx levels of 0.2 g/bhp-hr throughout the program target load of 12.6bar BMEP. The project showed that the range of loads could be extended to 16.5bar BMEP, therefore matching the reference lug line of the base 2007 MY Navistar 6.4L V8 engine. Results showed that the application of LTC provided a dramatic improvement over engine out emissions when compared to the base engine. Furthermore LTC improved thermal efficiency by over 5% from the base production engine when using the steady state 13 mode composite test as a benchmark. The key enablers included improvements in the air, fuel injection, and cooling systems made in Phases I and II. The outcome was the product of a careful integration of each component under an intelligent control system. The engine hardware provided the conditions to support LTC and the controller provided the necessary robustness for a stable combustion. Phase III provided a detailed account on the injection strategy used to meet the high load requirements. During this phase, the control strategy was implemented in a production automotive grade ECU to perform cycle-by-cycle combustion feedback on each of the engine cylinders. The control interacted on a cycle base with the injection system and with the Turbo-EGR systems according to their respective time constants. The result was a unique system that could, first, help optimize the combustion system and maintain high efficiency, and secondly, extend the steady state results to the transient mode of operation. The engine was upgraded in Phase IV with a Variable Valve Actuation system and a hybrid EGR loop. The impact of the more versatile EGR loop did not provide significant advantages, however the application of VVA proved to be an enabler to further extend the operation of LTC and gain considerable benefits in fuel economy and soot reduction. Finally

  7. Boiler using combustible fluid

    Science.gov (United States)

    Baumgartner, H.; Meier, J.G.

    1974-07-03

    A fluid fuel boiler is described comprising a combustion chamber, a cover on the combustion chamber having an opening for introducing a combustion-supporting gaseous fluid through said openings, means to impart rotation to the gaseous fluid about an axis of the combustion chamber, a burner for introducing a fluid fuel into the chamber mixed with the gaseous fluid for combustion thereof, the cover having a generally frustro-conical configuration diverging from the opening toward the interior of the chamber at an angle of between 15/sup 0/ and 55/sup 0/; means defining said combustion chamber having means defining a plurality of axial hot gas flow paths from a downstream portion of the combustion chamber to flow hot gases into an upstream portion of the combustion chamber, and means for diverting some of the hot gas flow along paths in a direction circumferentially of the combustion chamber, with the latter paths being immersed in the water flow path thereby to improve heat transfer and terminating in a gas outlet, the combustion chamber comprising at least one modular element, joined axially to the frustro-conical cover and coaxial therewith. The modular element comprises an inner ring and means of defining the circumferential, radial, and spiral flow paths of the hot gases.

  8. Particle Emissions from Biomass Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Szpila, Aneta; Bohgard, Mats [Lund Inst. of Technology (Sweden). Div. of Ergonomics and Aerosol Technology; Strand, Michael; Lillieblad, Lena; Sanati, Mehri [Vaexjoe Univ. (Sweden). Div. of Bioenergy Technology; Pagels, Joakim; Rissler, Jenny; Swietlicki, Erik; Gharibi, Arash [Lund Univ. (Sweden). Div. of Nuclear Physics

    2003-05-01

    We have shown that high concentrations of fine particles of the order of 2-7x10{sup -7} particles per cm{sup 3} are being formed in all the combustion units studied. There was a higher difference between the units in terms of particle mass concentrations. While the largest differences was found for gas-phase constituents (CO and THC) and polyaromatic hydrocarbons. In 5 out of 7 studied units, multi-cyclones were the only measure for flue-gas separation. The multicyclones had negligible effect on the particle number concentration and a small effect on the mass of particles smaller than 5 {mu}m. The separation efficiency was much higher for the electrostatic precipitators. The boiler load had a dramatic influence on the coarse mode concentration during combustion of forest residue. PM0.8-6 increased from below 5 mg/m{sup 3} to above 50 mg/m{sup 3} even at a moderate change in boiler load from medium to high. A similar but less pronounced trend was found during combustion of dry wood. PM0.8-PM6 increased from 12 to 23 mg/m{sup 3} when the load was changed from low to high. When increasing the load, the primary airflow taken through the grate is increased; this itself may lead to a higher potential of the air stream to carry coarse particles away from the combustion zone. Measurements with APS-instrument with higher time-resolution showed a corresponding increase in coarse mode number concentration with load. Additional factor influencing observed higher concentration of coarse mode during combustion of forest residues, could be relatively high ash content in this type of fuel (2.2 %) in comparison to dry wood (0.3 %) and pellets (0.5 %). With increasing load we also found a decrease in PM1 during combustion of forest residue. Whether this is caused by scavenging of volatilized material by the high coarse mode concentration or a result of a different amount of volatilized material available for formation of fine particles needs to be shown in future studies. The

  9. Acceleration of the chemistry solver for modeling DI engine combustion using dynamic adaptive chemistry (DAC) schemes

    Science.gov (United States)

    Shi, Yu; Liang, Long; Ge, Hai-Wen; Reitz, Rolf D.

    2010-03-01

    Acceleration of the chemistry solver for engine combustion is of much interest due to the fact that in practical engine simulations extensive computational time is spent solving the fuel oxidation and emission formation chemistry. A dynamic adaptive chemistry (DAC) scheme based on a directed relation graph error propagation (DRGEP) method has been applied to study homogeneous charge compression ignition (HCCI) engine combustion with detailed chemistry (over 500 species) previously using an R-value-based breadth-first search (RBFS) algorithm, which significantly reduced computational times (by as much as 30-fold). The present paper extends the use of this on-the-fly kinetic mechanism reduction scheme to model combustion in direct-injection (DI) engines. It was found that the DAC scheme becomes less efficient when applied to DI engine simulations using a kinetic mechanism of relatively small size and the accuracy of the original DAC scheme decreases for conventional non-premixed combustion engine. The present study also focuses on determination of search-initiating species, involvement of the NOx chemistry, selection of a proper error tolerance, as well as treatment of the interaction of chemical heat release and the fuel spray. Both the DAC schemes were integrated into the ERC KIVA-3v2 code, and simulations were conducted to compare the two schemes. In general, the present DAC scheme has better efficiency and similar accuracy compared to the previous DAC scheme. The efficiency depends on the size of the chemical kinetics mechanism used and the engine operating conditions. For cases using a small n-heptane kinetic mechanism of 34 species, 30% of the computational time is saved, and 50% for a larger n-heptane kinetic mechanism of 61 species. The paper also demonstrates that by combining the present DAC scheme with an adaptive multi-grid chemistry (AMC) solver, it is feasible to simulate a direct-injection engine using a detailed n-heptane mechanism with 543 species

  10. HCCI甲醇发动机的燃烧与排放特性%Combustion and Emission Characteristics of HCCI Engine Fueled with Methanol Fuel

    Institute of Scientific and Technical Information of China (English)

    陈韬; 何邦全; 谢辉; 赵华

    2007-01-01

    在Ricardo Hydra 单缸四冲程发动机上利用内部废气再循环策略实现了甲醇燃料的HCCI燃烧.通过调整HCCI发动机的过量空气系数和转速,研究了HCCI甲醇发动机的燃烧和排放特性.结果表明,甲醇燃料的HCCI燃烧不同于普通汽油,其着火更早、燃烧更快,但在低转速时,平均指示压力相对较低.甲醇燃料可以在更稀的混合气条件下实现HCCI燃烧.在相同的转速和过量空气系数下,甲醇燃料的NOx和HC排放低于汽油.

  11. 天然气HCCI发动机燃烧和排放的CFD研究%CFD Study on Combustion and Emissions of Natural Gas HCCI Engine

    Institute of Scientific and Technical Information of China (English)

    韩健; 郎静

    2006-01-01

    利用耦合详细化学反应机理的CFD软件FLUENT对天然气HCCI发动机的燃烧和排放物的生成过程进行了模拟计算,计算的缸内压力和温度与实验值有较好的一致性.计算结果表明,狭缝是缸内碳氢(HC)和一氧化碳(CO)排放的主要来源.HC主要由燃料本身组成;CO和甲醛有相似的生成及分布规律.天然气HCCI稀薄燃烧可以得到极低的NOx排放.

  12. NUMERICAL SIMULATION ON HCCI COMBUSTION PROCESS%均质混合气压缩着火燃烧过程的模拟研究

    Institute of Scientific and Technical Information of China (English)

    王志; 帅石金; 王建昕

    2008-01-01

    本文采用并行计算对HCCI燃烧过程进行三维数值模拟与解析,对比了采用不同数量CPU与不同规模机理时的计算效率,分析了采用不同机理以及单区和三维HCCI模拟的计算结果的影响.结果表明,合理采用并行计算和简化机理可以大幅度提高HCCI模拟计算效率.三维HCCI模拟相比于单区模拟显著提高了燃烧和排放的计算精度; HCCI燃烧过程中缸内存在明显的温度分层,燃烧呈现顺序放热.

  13. Study on the Relationship between External EGR and Gasoline - fueled HCCI Combustion%内部EGR与汽油燃料HCCI燃烧关系的探讨

    Institute of Scientific and Technical Information of China (English)

    祁俊荣; 钟绍华

    2006-01-01

    HCCI燃烧是一种新的发动机燃烧技术,介绍了HCCI燃烧的实现方式,指出EGR是最有可能获得四冲程汽油HCCI燃烧的方法,并且其可以通过早关排气阀得到;简要分析了内部EGR对HCCI燃烧的影响;阐述了为捕捉残余废气而改变气门正时过程中存在的泵气损失和回流损失问题.

  14. Impact Mechanism of EGR on Gasoline-Fueled HCCI Combustion%EGR对汽油机HCCI燃烧过程的影响机理

    Institute of Scientific and Technical Information of China (English)

    郑朝蕾; 张博; 刘春

    2013-01-01

    以甲苯掺比燃料作为汽油燃料替代混合物,利用零维单区化学动力学模型,在EGR率为20%时,分析和研究EGR中添加不同摩尔分数的CO、NO和CH2O对汽油机HCCI燃烧的化学作用,进而分析添加物对生成物中有害物质的影响.通过模拟分析可知,不同摩尔分数的添加物可以使气缸内的温度和压力有一定程度的提高,同时能够降低废气中的CO、NOx和UHC等有害物质的排放.

  15. Coal combustion products

    Science.gov (United States)

    Kalyoncu, R.S.; Olson, D.W.

    2001-01-01

    Coal-burning powerplants, which supply more than half of U.S. electricity, also generate coal combustion products, which can be both a resource and a disposal problem. The U.S. Geological Survey collaborates with the American Coal Ash Association in preparing its annual report on coal combustion products. This Fact Sheet answers questions about present and potential uses of coal combustion products.

  16. Research Combustion Laboratory (RCL)

    Data.gov (United States)

    Federal Laboratory Consortium — The Research Combustion Laboratory (RCL) develops aerospace propulsion technology by performing tests on propulsion components and materials. Altitudes up to 137,000...

  17. Combustion Byproducts Recycling Consortium

    Energy Technology Data Exchange (ETDEWEB)

    Paul Ziemkiewicz; Tamara Vandivort; Debra Pflughoeft-Hassett; Y. Paul Chugh; James Hower

    2008-08-31

    Ashlines: To promote and support the commercially viable and environmentally sound recycling of coal combustion byproducts for productive uses through scientific research, development, and field testing.

  18. Research Combustion Laboratory (RCL)

    Data.gov (United States)

    Federal Laboratory Consortium — The Research Combustion Laboratory (RCL) develops aerospace propulsion technology by performing tests on propulsion components and materials. Altitudes up to 137,000...

  19. Strobes: An oscillatory combustion

    NARCIS (Netherlands)

    Corbel, J.M.L.; Lingen, J.N.J. van; Zevenbergen, J.F.; Gijzeman, O.L.J.; Meijerink, A.

    2012-01-01

    Strobe compositions belong to the class of solid combustions. They are mixtures of powdered ingredients. When ignited, the combustion front evolves in an oscillatory fashion, and flashes of light are produced by intermittence. They have fascinated many scientists since their discovery at the beginni

  20. Strobes: An Oscillatory Combustion

    NARCIS (Netherlands)

    Corbel, J.M.L.; van Lingen, J.N.J.; Zevenbergen, J.F.; Gijzeman, O.L.J.; Meijerink, A.

    2012-01-01

    Strobe compositions belong to the class of solid combustions. They are mixtures of powdered ingredients. When ignited, the combustion front evolves in an oscillatory fashion, and flashes of light are produced by intermittence. They have fascinated many scientists since their discovery at the beginni

  1. Lectures on combustion theory

    Energy Technology Data Exchange (ETDEWEB)

    Burstein, S.Z.; Lax, P.D.; Sod, G.A. (eds.)

    1978-09-01

    Eleven lectures are presented on mathematical aspects of combustion: fluid dynamics, deflagrations and detonations, chemical kinetics, gas flows, combustion instability, flame spread above solids, spark ignition engines, burning rate of coal particles and hydrocarbon oxidation. Separate abstracts were prepared for three of the lectures. (DLC)

  2. Fifteenth combustion research conference

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-06-01

    The BES research efforts cover chemical reaction theory, experimental dynamics and spectroscopy, thermodynamics of combustion intermediates, chemical kinetics, reaction mechanisms, combustion diagnostics, and fluid dynamics and chemically reacting flows. 98 papers and abstracts are included. Separate abstracts were prepared for the papers.

  3. Coal Combustion Science

    Energy Technology Data Exchange (ETDEWEB)

    Hardesty, D.R. (ed.); Fletcher, T.H.; Hurt, R.H.; Baxter, L.L. (Sandia National Labs., Livermore, CA (United States))

    1991-08-01

    The objective of this activity is to support the Office of Fossil Energy in executing research on coal combustion science. This activity consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency Coal Combustion Science Project. Specific tasks for this activity include: (1) coal devolatilization - the objective of this risk is to characterize the physical and chemical processes that constitute the early devolatilization phase of coal combustion as a function of coal type, heating rate, particle size and temperature, and gas phase temperature and oxidizer concentration; (2) coal char combustion -the objective of this task is to characterize the physical and chemical processes involved during coal char combustion as a function of coal type, particle size and temperature, and gas phase temperature and oxygen concentration; (3) fate of mineral matter during coal combustion - the objective of this task is to establish a quantitative understanding of the mechanisms and rates of transformation, fragmentation, and deposition of mineral matter in coal combustion environments as a function of coal type, particle size and temperature, the initial forms and distribution of mineral species in the unreacted coal, and the local gas temperature and composition.

  4. Internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Helmich, M.J.; Hoagland, M.C.; Hubbard, R.L.; Schaub, F.S.

    1981-12-22

    A method of combusting natural gas fuel in a two cycle, turbocharged internal combustion engine substantially reduces the production of nitrogen-oxygen emissions. An improved turbocharger design provides increased air charging pressure, produces a controlled lean air/fuel mixture and lowers peak combustion temperatures. A jet cell ignition device ensures uniform, reliable ignition of the lean air/fuel mixture under all operating conditions and the lean air/fuel mixture in turn encourages complete fuel combustion and provides excellent combustion characteristics with methane, ethane and heavier paraffinic hydrocarbon fuels. These structural modifications and adjustment of other operating parameters combine to reduce nitric oxide (NO) and nitrogen dioxide (NO/sub 2/) emissions by as much as 75% while effecting only a negligible increase in fuel consumption.

  5. 基于直扩流道构型的RBCC发动机亚燃模态高效燃烧组织研究%Research on Ramjet-Mode Combustion Organization Based on Constant-Expansion Area Configuration in RBCC Combustor

    Institute of Scientific and Technical Information of China (English)

    何国强; 徐朝启; 秦飞; 刘佩进; 潘科玮

    2013-01-01

    针对支板喷注煤油和一次火箭引导燃烧的RBCC发动机,在亚燃模态下的高效燃烧组织和性能开展了实验研究和数值分析.实验验证了在亚燃模态低来流总温条件下,使用小流量富燃一次火箭产生的高温射流作为引导火焰,可以实现支板喷注二次燃料的可靠点火和高效稳定燃烧.通过数值模拟获得了燃烧室的详细流场特征和燃烧组织细节,分析表明支板后方集中的燃料热释放可形成扩张燃烧室流道中的“热力壅塞”;通过热力喉道的控制,实现了在直扩流道内的高效燃烧.研究表明:发动机在亚燃模态下燃烧组织应尽可能地使热力喉道处于燃烧室较后位置,使燃料在燃烧室高压区内充分燃烧释热,从而提高其燃烧效率.论文还研究了燃料支板喷注位置的影响,进一步开展RBCC发动机亚燃模态性能的优化.%The experimental and numerical investigations on the combustion organization and perform ance evaluation of RBCC combustor based on strut injection and primary rocket piloting combustion under ramjet mode have been performed.The experiment shows that the reliable ignition and stable combustion of secondary kerosene fuel by using fuel-rich primary rocket plume as piloting flame have been accomplished under the low total temperature of incoming airflow condition at ramjet mode.Moreover,the CFD simulation has been employed to obtain the detailed information of flowfield characteristics and combustion organization in RBCC combustor,and the results indicate that the thermal coking in the expansion flowpath has been formed due to the concentrated heat release behind the strut injectors.Reasonable heat release distribution along the combustor is important to get better performance.In order to achieve high combustion efficiency,the ‘ thermal throat' should be located on the rear of the combustor which leads to sufficient heat release by fuel combustion.Furthermore,based on current

  6. Modeling of the dynamical combustion of explosives: influence of mechanical properties; Modelisation de la combustion dynamique des explodifs: influence des proprietes mecaniques

    Energy Technology Data Exchange (ETDEWEB)

    Picart, D.; Pertuis, C. [CEA Le Ripault, 37 - Tours (France)

    1996-12-31

    Experimental observations performed during the combustion of solid explosives under pressure have shown an unexpected desensitization of the samples when damaged. A simplified method of combustion simulation inside a pressure cell is proposed in this study. The model used is based on the description of the mechanical behaviour of the solid phase. It allows to retrieve the overall experimental results, and in particular the occurrence of anomalous combustion modes. (J.S.) 8 refs.

  7. Effects of MTBE blended diesel fuel on diesel combustion and emissions; MTBE kongo keiyu ga diesel nensho haiki ni oyobosu eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Shundo, S.; Yokota, H.; Kakegawa, T. [Hino Motors, Ltd., Tokyo (Japan)

    1997-10-01

    The effects of MTBE (Methyl-t-butyl ether) blended diesel fuel on diesel combustion and emissions were studied. In conventional diesel combustion, the testing mode was carried out in conformity with the Japanese 13 mode. Furthermore, this fuel was applied to a new combustion system (Homogeneous Charge Intelligent Multiple Injection). MTBE blended diesel fuel is more effective in the case of new combustion system and very low NOx, PM capability is suggested. 6 refs., 6 figs., 2 tabs.

  8. Internal combustion engine for natural gas compressor operation

    Energy Technology Data Exchange (ETDEWEB)

    Hagen, Christopher; Babbitt, Guy

    2016-12-27

    This application concerns systems and methods for compressing natural gas with an internal combustion engine. In a representative embodiment, a method is featured which includes placing a first cylinder of an internal combustion engine in a compressor mode, and compressing a gas within the first cylinder, using the cylinder as a reciprocating compressor. In some embodiments a compression check valve system is used to regulate pressure and flow within cylinders of the engine during a compression process.

  9. Homogeneous Mixture Formation for HCCI of Diesel Engine%柴油机HCCI燃烧的均质混合气制备

    Institute of Scientific and Technical Information of China (English)

    李棠; 李理光

    2003-01-01

    介绍了均质充量压缩着火(HCCI)燃烧的概念、优缺点及其良好的发展前途与当前面临的困难.分析了HCCI混合气制备的重要性,总结了柴油机HCCI混合气制备的典型方法和成功经验,并分析了混合气制备对HCCI燃烧排放、着火相位的控制以及功率输出的影响,探讨并展望了HCCI混合气制备的可能发展方向.

  10. Flame spectra of solid propellants during unstable combustion.

    Science.gov (United States)

    Eisel, J. L.; Ryan, N. W.; Baer, A. D.

    1972-01-01

    The spectral and temporal details of the flames of a series of ammonium perchlorate-polyurethane propellants during both unstable and stable combustion were observed experimentally. A 400-scan per second optical spectrometer operating in the middle infrared region was used. During unstable combustion at low ratios of chamber free volume to nozzle throat area, three different frequencies were observed simultaneously. These were attributable to at least two mechanisms. During stable combustion periodic fluctuations in flame temperature and composition were also observed. Some aspects of theory of bulk mode instability were confirmed, but the assumptions of constant flame temperature and constant composition were found to be inaccurate.

  11. Sandia Combustion Research: Technical review

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-07-01

    This report contains reports from research programs conducted at the Sandia Combustion Research Facility. Research is presented under the following topics: laser based diagnostics; combustion chemistry; reacting flow; combustion in engines and commercial burners; coal combustion; and industrial processing. Individual projects were processed separately for entry onto the DOE databases.

  12. Development of High Efficiency and Low Emission Low Temperature Combustion Diesel Engine with Direct EGR Injection

    Science.gov (United States)

    Ho, R. J.; Kumaran, P.; Yusoff, M. Z.

    2016-03-01

    Focus on energy and environmental sustainability policy has put automotive research & development directed to developing high efficiency and low pollutant power train. Diffused flame controlled diesel combustion has reach its limitation and has driven R&D to explore other modes of combustions. Known effective mode of combustion to reduce emission are Low temperature combustion (LTC) and homogeneous charge combustion ignition by suppressing Nitrogen Oxide(NOx) and Particulate Matter (PM) formation. The key control to meet this requirement are chemical composition and distribution of fuel and gas during a combustion process. Most research to accomplish this goal is done by manipulating injected mass flow rate and varying indirect EGR through intake manifold. This research paper shows viable alternative direct combustion control via co-axial direct EGR injection with fuel injection process. A simulation study with OpenFOAM is conducted by varying EGR injection velocity and direct EGR injector diameter performed with under two conditions with non-combustion and combustion. n-heptane (C7H16) is used as surrogate fuel together with 57 species 290 semi-detailed chemical kinetic model developed by Chalmers University is used for combustion simulation. Simulation result indicates viability of co-axial EGR injection as a method for low temperature combustion control.

  13. Improving combustion efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Bulsari, A.; Wemberg, A.; Multas, A. [Nonlinear Solutions Oy (Finland)

    2009-06-15

    The paper describes how nonlinear models are used to improve the efficiency of coal combustion while keeping NOx and other emissions under desired limits in the Naantali 2 boiler of Fortum Power and Heat Oy. 16 refs., 6 figs.

  14. Fluidized coal combustion

    Science.gov (United States)

    Moynihan, P. I.; Young, D. L.

    1979-01-01

    Fluidized-bed coal combustion process, in which pulverized coal and limestone are burned in presence of forced air, may lead to efficient, reliable boilers with low sulfur dioxide and nitrogen dioxide emissions.

  15. Modelling diesel combustion

    CERN Document Server

    Lakshminarayanan, P A; Shi, Yu; Reitz, Rolf D

    2010-01-01

    The underlying principles of combustion phenomena are presented here, providing the basis for quantitative evaluation. These phenomena - ignition delay, fuel air mixing, rate of release, etc. - are then modelled for greater understanding and applicability.

  16. TENORM: Coal Combustion Residuals

    Science.gov (United States)

    Burning coal in boilers to create steam for power generation and industrial applications produces a number of combustion residuals. Naturally radioactive materials that were in the coal mostly end up in fly ash, bottom ash and boiler slag.

  17. Scramjet Combustion Processes

    Science.gov (United States)

    2010-09-01

    plan for these flights is as follows: Scramjet Combustion Processes RTO-EN-AVT-185 11 - 21 HyShot 5 – A Free-Flying Hypersonic Glider HyShot...5 will be a hypersonic glider designed to fly at Mach 8. It will separate from its rocket booster in space and perform controlled manoeuvres as it...RTO-EN-AVT-185 11 - 1 Scramjet Combustion Processes Michael Smart and Ray Stalker Centre for Hypersonics The University of Queensland

  18. Characterization and modes of occurrence of elements in feed coal and coal combustion products from a power plant utilizing low-sulfur coal from the Powder River Basin, Wyoming

    Science.gov (United States)

    Brownfield, Michael E.; Cathcart, James D.; Affolter, Ronald H.; Brownfield, Isabelle K.; Rice, Cynthia A.; O'Connor, Joseph T.; Zielinski, Robert A.; Bullock, John H.; Hower, James C.; Meeker, Gregory P.

    2005-01-01

    The U.S. Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana utility company to determine the physical and chemical properties of feed coal and coal combustion products from a coal-fired power plant. The Indiana power plant utilizes a low-sulfur (0.23 to 0.47 weight percent S) and lowash (4.9 to 6.3 weight percent ash) subbituminous coal from the Wyodak-Anderson coal zone in the Tongue River Member of the Paleocene Fort Union Formation, Powder River Basin, Wyoming. Based on scanning electron microscope and X-ray diffraction analyses of feed coal samples, two mineral suites were identified: (1) a primary or detrital suite consisting of quartz (including beta-form grains), biotite, feldspar, and minor zircon; and (2) a secondary authigenic mineral suite containing alumino-phosphates (crandallite and gorceixite), kaolinite, carbonates (calcite and dolomite), quartz, anatase, barite, and pyrite. The primary mineral suite is interpreted, in part, to be of volcanic origin, whereas the authigenic mineral suite is interpreted, in part, to be the result of the alteration of the volcanic minerals. The mineral suites have contributed to the higher amounts of barium, calcium, magnesium, phosphorus, sodium, strontium, and titanium in the Powder River Basin feed coals in comparison to eastern coals. X-ray diffraction analysis indicates that (1) fly ash is mostly aluminate glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals; and (2) bottom ash is predominantly quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite, and spinel group minerals. Microprobe and scanning electron microscope analyses of fly ash samples revealed quartz, zircon, and monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, wollastonite, and periclase. The abundant calcium and

  19. Sandia Combustion Research Program

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, S.C.; Palmer, R.E.; Montana, C.A. (eds.)

    1988-01-01

    During the late 1970s, in response to a national energy crisis, Sandia proposed to the US Department of Energy (DOE) a new, ambitious program in combustion research. Shortly thereafter, the Combustion Research Facility (CRF) was established at Sandia's Livermore location. Designated a ''user facility,'' the charter of the CRF was to develop and maintain special-purpose resources to support a nationwide initiative-involving US inventories, industry, and national laboratories--to improve our understanding and control of combustion. This report includes descriptions several research projects which have been simulated by working groups and involve the on-site participation of industry scientists. DOE's Industry Technology Fellowship program, supported through the Office of Energy Research, has been instrumental in the success of some of these joint efforts. The remainder of this report presents results of calendar year 1988, separated thematically into eleven categories. Referred journal articles appearing in print during 1988 and selected other publications are included at the end of Section 11. Our traditional'' research activities--combustion chemistry, reacting flows, diagnostics, engine and coal combustion--have been supplemented by a new effort aimed at understanding combustion-related issues in the management of toxic and hazardous materials.

  20. METC Combustion Research Facility

    Energy Technology Data Exchange (ETDEWEB)

    Halow, J.S.; Maloney, D.J.; Richards, G.A.

    1993-11-01

    The objective of the Morgantown Energy Technology Center (METC) high pressure combustion facility is to provide a mid-scale facility for combustion and cleanup research to support DOE`s advanced gas turbine, pressurized, fluidized-bed combustion, and hot gas cleanup programs. The facility is intended to fill a gap between lab scale facilities typical of universities and large scale combustion/turbine test facilities typical of turbine manufacturers. The facility is now available to industry and university partners through cooperative programs with METC. High pressure combustion research is also important to other DOE programs. Integrated gasification combined cycle (IGCC) systems and second-generation, pressurized, fluidized-bed combustion (PFBC) systems use gas turbines/electric generators as primary power generators. The turbine combustors play an important role in achieving high efficiency and low emissions in these novel systems. These systems use a coal-derived fuel gas as fuel for the turbine combustor. The METC facility is designed to support coal fuel gas-fired combustors as well as the natural gas fired combustor used in the advanced turbine program.

  1. Effect of CO Combustion Promoters on Combustion Air Partition in FCC under Nearly Complete Combustion

    Institute of Scientific and Technical Information of China (English)

    王锐; 罗雄麟; 许锋

    2014-01-01

    With CO combustion promoters, the role of combustion air flow rate for concerns of economics and control is important. The combustion air is conceptually divided to three parts:the air consumed by coke burning, the air consumed by CO combustion and the air unreacted. A mathematical model of a fluid catalytic cracking (FCC) unit, which includes a quantitative correlation of CO heterogeneous combustion and the amount of CO combustion promoters, is introduced to investigate the effects of promoters on the three parts of combustion air. The results show that the air consumed by coke burning is almost linear to combustion air flow rate, while the air consumed by CO combustion promoters tends to saturate as combustion air flow rate increases, indicating that higher air flow rate can only be used as a manipulated variable to control the oxygen content for an economic concern.

  2. Modeling of NO sensitization of IC engines surrogate fuels auto-ignition and combustion

    CERN Document Server

    Anderlohr, Jörg; Bounaceur, Roda; Battin-Leclerc, Frédérique

    2009-01-01

    This paper presents a new chemical kinetic model developed for the simulation of auto-ignition and combustion of engine surrogate fuel mixtures sensitized by the presence of NOx. The chemical mechanism is based on the PRF auto-ignition model (n-heptane/iso-octane) of Buda et al. [1] and the NO/n-butane/n-pentane model of Glaude et al. [2]. The later mechanism has been taken as a reference for the reactions of NOx with larger alcanes (n-heptane, iso-octane). A coherent two components engine fuel surrogate mechanism has been generated which accounts for the influence of NOx on auto-ignition. The mechanism has been validated for temperatures between 700 K and 1100 K and pressures between 1 and 10 atm covering the temperature and pressure ranges characteristic of engine post-oxidation thermodynamic conditions. Experiments used for validation include jet stirred reactor conditions for species evolution as a function of temperature, as well as diesel HCCI engine experiments for auto-ignition delay time measurements...

  3. Study of SI-HCCI-SI Transition on a Port Fuel Injection Engine Equipped with 4VVAS%4VVAS双模式发动机SI-HCCI燃烧模式过渡研究

    Institute of Scientific and Technical Information of China (English)

    张岩; 谢辉; 周能辉; 陈韬; 赵华

    2008-01-01

    提出一种可以实现SI/HCCI双模式运行的汽油机方案.将自行设计和研制的基于进排气门升程和相位等4个变量连续可变的HCCI(Homogeneous Charge Compression Igniton)汽油机缸盖安装在单缸试验机上,建立了4VVAS-HCCI汽油机原理性样机平台.通过在该平台上的试验研究,探索了HCCI/SI两种燃烧模式过渡过程的动态控制策略.结果表明:配备4VVAS(4 Variable Valve Actuaion System)缸盖的发动机,可以根据工况需要运行于HCCI或SI(Spark Ignition)燃烧模式;通过4VVAS系统对内部残余废气快速有效管理,可以完成HCCI-SI动态平滑过渡;由于热惯性的存在,从SI向HCCI燃烧模式过渡难于从HCCI向SI过渡;对燃烧模式过渡过程的控制可以归结为对残余废气率的动态管理和对混合放热率型线的设计.

  4. Internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Williams, G.J.

    1986-06-03

    A variable power internal combustion engine is described which consists of: a separate air compressor for receiving and compressing a flow of air to a given pressure, the compressor having an inlet valve introducing a flow of air into the compressor and an outlet valve for exhausting compressed air out of the compressor into a compressed air storage means, at least one expander having a cylinder, a cylinder head closing an end of the cylinder, a piston reciprocally mounted in the cylinder for movement away from the cylinder head in a power stroke from an initial position defining a combustion chamber within the cylinder between the cylinder head and the piston, the compressed air storage means receiving the pressurized flow of air from the compressor and being of a volume adequate to provide compressed air in the combustion chamber essentially at the given pressure essentially over the power output of the engine, means for introducing an amount of combustible fuel in the compressed charge to be present with compressed air in the combustion chamber and providing combustion of the amount of fuel in the cylinder with the inlet and exhaust valves closed, cam shaft means in contact with the piston for absorbing and storing the energy of the power stroke of the piston and controlling movement of the piston within the cylinder during the exhaust stroke; the means for varying the volume of the combustion chamber being controlled in accordance with power requirements to provide variable power output and improved efficiency of the engine at power outputs reduced relative to a given design power output of the engine by providing a variable expansion ratio of a minimum of at least about 30 to 1 at the given design power output and higher with reduced power output.

  5. Combustion of nuclear matter into strange matter

    Energy Technology Data Exchange (ETDEWEB)

    Lugones, G. (Departamento di Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, (1900) La Plata (Argentina)); Benvenuto, O.G.; Vucetich, H. (Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, (1900) La Plata (Argentina))

    1994-11-15

    We study the properties of the combustion of pure neutron matter into strange matter in the framework of relativistic hydrodynamical theory of combustion. Because of the uncertainties in the actual properties of neutron matter, we employ the free neutron, Bethe-Johnson, Lattimer-Ravenhall, and Walecka equations of state and for strange matter we adopt the MIT bag model approximation. We find that combustion is possible for free neutron, Bethe-Johnson, and Lattimer-Ravenhall neutron matter but not for Walecka neutron matter. We interpret these results using a simple polytropic approximation showing that there exists a general flammability condition. We also study the burning of neutron matter into strange matter in a pipe showing that hydrodynamics demands flames faster than predicted by kinetics by several orders of magnitude, implying that the flame must be turbulent. Also the conditions for the deflagration to detonation transition are addressed, showing that in a pipe some of them are satisfied, strongly suggesting that the actual combustion mode should be detonation.

  6. Particulate emissions from residential wood combustion

    DEFF Research Database (Denmark)

    Luis Teles de Carvalho, Ricardo; Jensen, Ole Michael; Tarelho, Luis A. C.

    Residential wood combustion (RWC) in fireplaces and conventional appliances is the main contributor to fine particulate matter (PM2.5) emissions in Denmark and Portugal representing more than 30% of the total emissions [1;2]. Such estimations are uncertain concerning the wood consumption and offi......Residential wood combustion (RWC) in fireplaces and conventional appliances is the main contributor to fine particulate matter (PM2.5) emissions in Denmark and Portugal representing more than 30% of the total emissions [1;2]. Such estimations are uncertain concerning the wood consumption.......5 emissions within a specific “wood burning living area”, but one Danish study exists [4]. In previous inventories distinct combustion air operation modes and the growing penetration of automate wood-burning stoves have not been considered. The present work aims to discuss opportunities for improving...... Portuguese combustion practices in laboratory tests. This study highlights that the previous PM2.5 emission inventories in Denmark and Portugal did not consider the possible variations on fuel moisture, dimensions of wood-logs and air-inlet operation patterns, although they are very important, especially...

  7. Combustible structural composites and methods of forming combustible structural composites

    Science.gov (United States)

    Daniels, Michael A.; Heaps, Ronald J.; Steffler, Eric D; Swank, William D.

    2011-08-30

    Combustible structural composites and methods of forming same are disclosed. In an embodiment, a combustible structural composite includes combustible material comprising a fuel metal and a metal oxide. The fuel metal is present in the combustible material at a weight ratio from 1:9 to 1:1 of the fuel metal to the metal oxide. The fuel metal and the metal oxide are capable of exothermically reacting upon application of energy at or above a threshold value to support self-sustaining combustion of the combustible material within the combustible structural composite. Structural-reinforcing fibers are present in the composite at a weight ratio from 1:20 to 10:1 of the structural-reinforcing fibers to the combustible material. Other embodiments and aspects are disclosed.

  8. Combustion and regulation; Combustion et reglementation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This conference was organized after the publication of the French by-law no 2010 relative to combustion installations and to the abatement of atmospheric pollution. Five topics were discussed during the conference: the new regulations, their content, innovations and modalities of application; the means of energy suppliers to face the new provisions and their schedule; the manufacturers proposals for existing installations and the new equipments; the administration control; and the impact of the new measures on exploitation and engineering. Twenty papers and 2 journal articles are reported in these proceedings. (J.S.)

  9. Experimental investigation of combustion mechanisms of kerosene-fueled scramjet engines with double-cavity flameholders

    Institute of Scientific and Technical Information of China (English)

    Yu Pan; Jian-Guo Tan; Jian-Han Liang; Wei-Dong Liu; Zhen-Guo Wang

    2011-01-01

    A scramjet combustor with double cavitybased flameholders was experimentally studied in a directconnected test bed with the inflow conditions of M =2.64,Pt =1.84 MPa,Tt =1 300 K.Successful ignition and selfsustained combustion with room temperature kerosene was achieved using pilot hydrogen,and kerosene was vertically injected into the combustor through 4×φ0.5 mm holes mounted on the wall.For different equivalence ratios and different injection schemes with both tandem cavities and parallel cavities,flow fields were obtained and compared using a high speed camera and a Schlieren system.Results revealed that the combustor inside the flow field was greatly influenced by the cavity installation scheme,cavities in tandem easily to form a single side flame distribution,and cavities in parallel are more likely to form a joint flame,forming a choked combustion mode.The supersonic combustion flame was a kind of diffusion flame and there were two kinds of combustion modes.In the unchoked combustion mode,both subsonic and supersonic combustion regions existed.While in the choked mode,the combustion region was fully subsonic with strong shock propagating upstream.Results also showed that there was a balance point between the boundary separation and shock enhanced combustion,depending on the intensity of heat release.

  10. 催化燃烧对HCCI发动机着火点、燃烧性能及排放的影响%Influences of Catalytic Combustion on Ignition Timing, Combustion Capability and Emissions of HCCI Engine

    Institute of Scientific and Technical Information of China (English)

    曾文; 解茂昭

    2007-01-01

    对甲烷在催化剂铑(Rh)表面的反应机理进行了分析.通过修改CHEMKIN软件包中的SENKIN模块,对活塞顶涂有催化剂的HCCI发动机的燃烧过程进行了数值计算,建立了单区、多区模型.利用单区模型分析了催化燃烧对HCCI发动机着火时刻的影响,结果表明在控制HCCI发动机着火时刻方面催化燃烧有其他方式所没有的优势;利用多区模型分析了催化燃烧对HCCI发动机的燃烧性能及HC、CO、NOx排放的影响,结果表明催化燃烧对燃烧效率、着火持续期有较大的影响,同时能降低HC、CO的排放,但会提高NOx的排放.

  11. Studies in combustion dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Koszykowski, M.L. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The goal of this program is to develop a fundamental understanding and a quantitative predictive capability in combustion modeling. A large part of the understanding of the chemistry of combustion processes comes from {open_quotes}chemical kinetic modeling.{close_quotes} However, successful modeling is not an isolated activity. It necessarily involves the integration of methods and results from several diverse disciplines and activities including theoretical chemistry, elementary reaction kinetics, fluid mechanics and computational science. Recently the authors have developed and utilized new tools for parallel processing to implement the first numerical model of a turbulent diffusion flame including a {open_quotes}full{close_quotes} chemical mechanism.

  12. Alcohol combustion chemistry

    KAUST Repository

    Sarathy, Mani

    2014-10-01

    Alternative transportation fuels, preferably from renewable sources, include alcohols with up to five or even more carbon atoms. They are considered promising because they can be derived from biological matter via established and new processes. In addition, many of their physical-chemical properties are compatible with the requirements of modern engines, which make them attractive either as replacements for fossil fuels or as fuel additives. Indeed, alcohol fuels have been used since the early years of automobile production, particularly in Brazil, where ethanol has a long history of use as an automobile fuel. Recently, increasing attention has been paid to the use of non-petroleum-based fuels made from biological sources, including alcohols (predominantly ethanol), as important liquid biofuels. Today, the ethanol fuel that is offered in the market is mainly made from sugar cane or corn. Its production as a first-generation biofuel, especially in North America, has been associated with publicly discussed drawbacks, such as reduction in the food supply, need for fertilization, extensive water usage, and other ecological concerns. More environmentally friendly processes are being considered to produce alcohols from inedible plants or plant parts on wasteland. While biofuel production and its use (especially ethanol and biodiesel) in internal combustion engines have been the focus of several recent reviews, a dedicated overview and summary of research on alcohol combustion chemistry is still lacking. Besides ethanol, many linear and branched members of the alcohol family, from methanol to hexanols, have been studied, with a particular emphasis on butanols. These fuels and their combustion properties, including their ignition, flame propagation, and extinction characteristics, their pyrolysis and oxidation reactions, and their potential to produce pollutant emissions have been intensively investigated in dedicated experiments on the laboratory and the engine scale

  13. Radiative Augmented Combustion.

    Science.gov (United States)

    1985-08-12

    86-0085 In 00I to RADIATIVE AUGMENTED COMBUSTION MOSHE LAVID M.L. ENERGIA , INC. P.O. BOX 1468 1 PRINCETON, NEW JERSEY 08542 AUGUST 1985 *.. plo...Combustion conducted at M.L. ENERGIA . It is funded by the Air Force Office of Scientific Research under Contract No. F49620-83-C-0133, with Dr. J.M...reported. It covers the second year of the contract, from July 15, 1984 through July 14, 1985. The work was performed at ENERGIA , Princeton, New Jersey

  14. Transition nozzle combustion system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Won-Wook; McMahan, Kevin Weston; Maldonado, Jaime Javier

    2016-11-29

    The present application provides a combustion system for use with a cooling flow. The combustion system may include a head end, an aft end, a transition nozzle extending from the head end to the aft end, and an impingement sleeve surrounding the transition nozzle. The impingement sleeve may define a first cavity in communication with the head end for a first portion of the cooling flow and a second cavity in communication with the aft end for a second portion of the cooling flow. The transition nozzle may include a number of cooling holes thereon in communication with the second portion of the cooling flow.

  15. On gas and particle radiation in pulverized fuel combustion furnaces

    DEFF Research Database (Denmark)

    Yin, Chungen

    2015-01-01

    Radiation is the principal mode of heat transfer in a combustor. This paper presents a refined weighted sum of gray gases model for computational fluid dynamics modelling of conventional air-fuel combustion, which has greater accuracy and completeness than the existing gaseous radiative property....... Although the refined gaseous radiative property model shows great advantages in gaseous fuel combustion modelling, its impacts are largely compromised in pulverized solid fuel combustion, in which particle-radiation interaction plays the dominant role in radiation heat transfer due to high particle loading....... Use of conversion-dependent particle emissivity and scattering factor will not only change the particle heating and reaction history, but also alter the radiation intensity and thus temperature profiles in the furnace. For radiation modelling in pulverized fuel combustion, the priority needs...

  16. Toxicology of Biodiesel Combustion products

    Science.gov (United States)

    1. Introduction The toxicology of combusted biodiesel is an emerging field. Much of the current knowledge about biological responses and health effects stems from studies of exposures to other fuel sources (typically petroleum diesel, gasoline, and wood) incompletely combusted. ...

  17. Experimental combustion an introduction

    CERN Document Server

    Mishra, D P

    2014-01-01

    ""… other books available in this area do not cover the detailed topics covered here. Energy and combustion is a hot issue. It is expected to be even hotter with more demand in this area as we search for cleaner methods of energy conversion from chemical to thermal energy.""-Ashwani K. Gupta, Department of Mechanical Engineering, University of Maryland, College Park, USA

  18. Coal combustion research

    Energy Technology Data Exchange (ETDEWEB)

    Daw, C.S.

    1996-06-01

    This section describes research and development related to coal combustion being performed for the Fossil Energy Program under the direction of the Morgantown Energy Technology Center. The key activity involves the application of chaos theory for the diagnosis and control of fossil energy processes.

  19. Optical Tomography in Combustion

    DEFF Research Database (Denmark)

    Evseev, Vadim

    . JQSRT 113 (2012) 2222, 10.1016/j.jqsrt.2012.07.015] included in the PhD thesis as an attachment. The knowledge and experience gained in the PhD project is the first important step towards introducing the advanced optical tomography methods of combustion diagnostics developed in the project to future...

  20. Combustion Models in Finance

    CERN Document Server

    Tannous, C

    2001-01-01

    Combustion reaction kinetics models are used for the description of a special class of bursty Financial Time Series. The small number of parameters they depend upon enable financial analysts to predict the time as well as the magnitude of the jump of the value of the portfolio. Several Financial Time Series are analysed within this framework and applications are given.

  1. Flameless Combustion Workshop

    Science.gov (United States)

    2005-09-20

    operating hours, to produce low emission levels of NOx, CO and UHC . Gas turbine combustion stability has increasingly become a crucial design issue as...achieved proved: "* Safe and reliable operation ofgas turbine combustors "* Low emissions of NO., CO and UHC These results have clear economically

  2. Theoretical studies of hydrocarbon combustion chemistry. Annual progress report

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, H.F. III

    1994-08-01

    The author reports here the results of DZP CISD calculations for methylcarbene. Geometry, symmetry, and vibrational modes for the radical are reported for both the singlet and the triplet state. Future work will focus on the ethyl radical-oxygen interaction relevant to hydrocarbon combustion.

  3. Optical Engines as Representative Tools in the Development of New Combustion Engine Concepts Moteurs transparents comme outils représentatifs dans le développement de nouveaux concepts des moteurs à combustion interne

    Directory of Open Access Journals (Sweden)

    Kashdan J.

    2011-11-01

    Full Text Available Single cylinder optical engines are used for Internal Combustion (IC engine research as they allow for the application of qualitative and quantitative non-intrusive, diagnostic techniques to study in-cylinder flow, mixing, combustion and emissions phenomena. Such experimental data is not only important for the validation of computational models but can also provide a detailed insight into the physical processes occurring in-cylinder which is useful for the further development of new combustion strategies such as gasoline Homogeneous Charge Compression Ignition (HCCI and Diesel Low Temperature Combustion (LTC. In this context, it is therefore important to ensure that the performance of optical engines is comparable to standard all-metal engines. A comparison of optical and all-metal engine combustion and emissions performance was performed within the present study. The objective was to investigate the principal differences between optical and all-metal engines and understand how these differences ultimately affect mixing, combustion and emissions formation processes. Experimental results reveal the significant impact of differences in combustion chamber wall temperatures between optical and standard engine piston bowls on combustion phasing and engine-out emissions. Quantitative measurements of piston wall temperatures using a laser-induced phosphorescence technique were performed which allowed the subsequent definition of appropriate engine operating strategies so as to compensate for differences in heat transfer properties. Furthermore, differences in combustion chamber geometry were also studied. Geometrical differences can arise as a result of dynamic (compressive/tensile and thermal loading of the extended piston-liner assembly on the optical engine, potentially leading to changes in the effective Compression Ratio. In addition, intake charge dilution in optical engines is often achieved via the use of simulated Exhaust Gas Recirculation

  4. Combustion calorimetry experimental chemical thermodynamics

    CERN Document Server

    Sunner, Stig

    1979-01-01

    Combustion Calorimetry deals with expertise knowledge concerning the calorimetry of combustion reactions of an element or compound. After defining the use of units and physical constants, the book discusses the basic principles of combustion calorimetry and the various instruments and calorimeters used in the experiments to measure operations concerning temperatures and its time variations. One paper discusses the theory and design criteria of combustion calorimeter calibration. Another paper discusses the results obtained from a combustion calorimeter after it has measured the energy or entha

  5. Modelling of CWS combustion process

    Science.gov (United States)

    Rybenko, I. A.; Ermakova, L. A.

    2016-10-01

    The paper considers the combustion process of coal water slurry (CWS) drops. The physico-chemical process scheme consisting of several independent parallel-sequential stages is offered. This scheme of drops combustion process is proved by the particle size distribution test and research stereomicroscopic analysis of combustion products. The results of mathematical modelling and optimization of stationary regimes of CWS combustion are provided. During modeling the problem of defining possible equilibrium composition of products, which can be obtained as a result of CWS combustion processes at different temperatures, is solved.

  6. Pulsed atmospheric fluidized bed combustion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  7. Large eddy simulation of combustion instability in a tripropellant air heater

    Science.gov (United States)

    Yuan, Lei; Shen, Chibing

    2016-12-01

    This research is motivated by the issue associated with high frequency combustion instability. Large eddy simulation was performed to investigate spontaneous combustion instability in an air/LO2/C2H5OH tripropellant air heater. The simulation predicts self-excited transverse oscillations. Overall behavior of combustion instability including pressure time histories, mode shapes, Rayleigh index and unsteady response of the injector were studied in detail. Special emphasis was given to the flame behavior, droplet trajectories, pressure evolutions, and formation of large-scale vortical structures during combustion instability in present air heater. Furthermore, in contrast to previous investigations, a new process is identified in the simulation that may feed energy into the acoustic mode and drive combustion instability.

  8. 富氧燃煤锅炉烟气再循环方式选择与水分平衡计算%Mode Selection of Flue Gas Recirculation and Balance Calculation of Water Vapor Content for Oxy-Coal Combustion Boilers

    Institute of Scientific and Technical Information of China (English)

    阎维平; 董静兰; 马凯

    2011-01-01

    Taking the 300 MW oxy-coal combustion boiler as an object of study,the water vapor content in flue gas and the auxiliary power consumption were calculated and compared,at different modes of secondary flue gas recirculation,with the flue gas dehydrated by DCC method or dehydrated and desulphurized by FGD+DCC process.Results show that when the flue gas is merely dehydrated by DCC,if dehydration is not applied in the secondary flue gas recirculation,the volumetric fraction of water vapor in flue gas from oxy-coal combustion system will be 10%-15% higher than that from air combustion;if dehydration is applied in the secondary flue gas recirculation,the former one will be 3% higher than the latter one.Whereas in a FGD+DCC arrangement,when both desulphurization and dehydration are applied in the secondary flue gas recirculation,the water vapor content in flue gas will be slightly higher than that only DCC is used and no dehydration is adopted in the secondary flue gas recirculation.At a recirculating water temperature of 30 ℃,the volumetric fraction of water vapor at DCC outlet is about 4.28%.The total power consumption of fan reaches the minimum under single DCC condition at the mode of dry flue gas recirculation.%在不同的二次烟气再循环方式下,以300 MW富氧燃烧锅炉机组为例,对分别采用直接接触式冷却器(DCC)进行烟气脱水和湿式脱硫(FGD)与DCC串联进行烟气脱硫及脱水的富氧燃烧系统详细计算并比较了烟气中水蒸气体积分数的变化,并计算和比较了各种布置方式下的风机功耗.结果表明:单独采用DCC脱水情况下,锅炉烟气水蒸气体积分数比空气燃烧方式下高10%-15%;二次循环烟气脱水时,锅炉烟气中的水蒸气含量比空气燃烧方式下高约3%;FGD与DCC串联布置时的锅炉流通烟气水蒸气含量略高于采用单独DCC时二次循环烟气脱水的水蒸气含量;电厂循环水温度为30℃时,DCC出口烟气理

  9. 柴油燃料HCCI燃烧影响因素的试验研究%EXPERIMENT STUDY ON INFLUENTIAL FACTORS OF DIESEL-FUELED HCCI

    Institute of Scientific and Technical Information of China (English)

    石磊; 邓康耀; 崔毅

    2005-01-01

    本文采用在进气上止点附近进行柴油喷射,利用缸内高温残余废气促进燃油蒸发形成均质混合气,实现了柴油燃料的均质压燃(HCCI).试验结果表明柴油燃料HCCI燃烧的放热规律呈现低温和高温放热两个阶段,并且NOx排放可以降低95%~98%.本文主要研究了影响HCCI燃烧的因素,指出负荷增大、进气温度增加和负气门重叠期的增加使HCCI着火提前,而外部EGR率的增大可以推迟着火.因此对于低温自燃性好的燃料,冷EGR是控制其HCCI着火燃烧过程的有效措施.

  10. Time Resolved FTIR Analysis of Combustion of Ethanol and Gasoline Combustion in AN Internal Combustion Engine

    Science.gov (United States)

    White, Allen R.; Sakai, Stephen; Devasher, Rebecca B.

    2011-06-01

    In order to pursue In Situ measurements in an internal combustion engine, a MegaTech Mark III transparent spark ignition engine was modified with a sapphire combustion chamber. This modification will allow the transmission of infrared radiation for time-resolved spectroscopic measurements by an infrared spectrometer. By using a Step-scan equipped Fourier transform spectrometer, temporally resolved infrared spectral data were acquired and compared for combustion in the modified Mark III engine. Measurements performed with the FTIR system provide insight into the energy transfer vectors that precede combustion and also provides an in situ measurement of the progress of combustion. Measurements were performed using ethanol and gasoline.

  11. Experimental chemical thermodynamics. Volume I. Combustion calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Sunner, S.; Mansson, M. (eds.)

    1979-01-01

    This book contains 18 chapters. The information included is: units and physical constants; basic principles of combustion calorimetry; calibration of combustion calorimeters; test and auxiliary substances in combustion calorimetry; strategies in the calculation of standard-state energies of combustion from the experimentally determined quantities; assignments of uncertainties; presentation of combustion calorimetric data in the primary literature; general techniques for combustion of liquid/solid organic compounds by oxygen bomb calorimetry; combustion of liquid/solid organic compounds with non-metallic hetero-atoms; combustion calorimetry of metals and simple metallic compounds; combustion calorimetry of organometallic compounds; combustion in fluorine and other halogens; bomb combustion of gaseous compounds in oxygen; oxygen flame calorimetry; fluorine flame calorimetry; combustion calorimetry as a technological service; trends in combustion calorimetry; and from the history of combustion calorimetry. (DP)

  12. Design trends and operating problems in combustion modification of industrial boilers. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Locklin, D.W.; Krause, H.H.; Putnam, A.A.; Kropp, E.L.; Reid, W.T.

    1974-04-01

    The report gives results of an air pollution emissions control study to: characterize the current field population of industrial boilers; identify trends in boiler design; and assess operating problems associated with combustion modification. Statistics were analyzed to describe the field population and recent sales trends for firetube and watertube industrial boilers in the range from 10 million to 500 million Btu/hr. Boiler capacity, design type, mode of direction, primary and secondary fuels, firing method (for coal), industrial classification, and geographic region of the boiler installation were all considered. When combustion modifications are used to control nitrogen oxide emissions from industrial boilers, practical operating problems may arise, namely: fireside corrosion and deposits on boiler tubes; and flame instability, including blow-off, flashback, combustion-driven oscillations, and combustion noise or roar. These problems were assessed and research needs were identified in relation to such combustion modifications as low-excess-air operation, staged combustion, and fluegas recirculation. (GRA)

  13. Pulverized coal torch combustion in a furnace with plasma-coal system

    Science.gov (United States)

    Messerle, V. E.; Ustimenko, A. B.; Askarova, A. S.; Nagibin, A. O.

    2010-09-01

    Combustion of a pulverized coal torch has been numerically simulated on the basis of the equations of multicomponent turbulent two-phase flows. The results of three-dimensional simulation of conventional and plasma activated coal combustion in a furnace are presented. Computer code Cinar ICE was verified at coal combustion in the experimental furnace with thermal power of 3 MW that was equipped with plasma-fuel system. Operation of the furnace has been studied at the conventional combustion mode and with plasma activation of coal combustion. Influence of plasma activation of combustion on thermotechnical characteristics of the torch and decrease of carbon loss and nitrogen oxides concentration at the furnace outlet has been revealed.

  14. Spray combustion of Jet-A and diesel fuels in a constant volume combustion chamber

    KAUST Repository

    Jing, Wei

    2015-01-01

    wider region of OH∗ in the downstream locations where only OH∗ emission is observed. The intensity of OH∗ is higher for Jet-A than diesel under low O2 concentration but lower under high O2 concentration. The intensity of NL is higher for Jet-A for all the conditions investigated. However, the intensities of Band A and Band B are lower for Jet-A for all these conditions. Based on the imaging of multiple-band flame emissions, the spray flame structures were further analyzed for the two fuels under both low temperature and conventional combustion modes. Conceptual flame structures were proposed to complement the previous conceptual models for spray combustion under different combustion modes.

  15. Aerosols from biomass combustion

    Energy Technology Data Exchange (ETDEWEB)

    Nussbaumer, T.

    2001-07-01

    This report is the proceedings of a seminar on biomass combustion and aerosol production organised jointly by the International Energy Agency's (IEA) Task 32 on bio energy and the Swiss Federal Office of Energy (SFOE). This collection of 16 papers discusses the production of aerosols and fine particles by the burning of biomass and their effects. Expert knowledge on the environmental impact of aerosols, formation mechanisms, measurement technologies, methods of analysis and measures to be taken to reduce such emissions is presented. The seminar, visited by 50 participants from 11 countries, shows, according to the authors, that the reduction of aerosol emissions resulting from biomass combustion will remain a challenge for the future.

  16. Combustion science and engineering

    CERN Document Server

    Annamalai, Kalyan

    2006-01-01

    Introduction and Review of Thermodynamics Introduction Combustion Terminology Matter and Its Properties Microscopic Overview of Thermodynamics Conservation of Mass and Energy and the First Law of Thermodynamics The Second Law of Thermodynamics Summary Stoichiometry and Thermochemistry of Reacting Systems Introduction Overall Reactions Gas Analyses Global Conservation Equations for Reacting Systems Thermochemistry Summary Appendix Reaction Direction and Equilibrium Introduction Reaction Direction and Chemical Equilibrium Chemical Equilibrium Relations Vant Hoff Equation Adi

  17. Combustion Characteristics of Sprays

    Science.gov (United States)

    1989-08-01

    regarded by implication or otherwise, or in any way licensing the holder or any other person or corporation, or conveying any rights or permission to...00 _’N 1. TI TLE inctuat Security CZaaafication5 Combustion Characteristics of Sprays 12. PERSONAL AUTHOR(S) Sohrab, Siavash H. 13& TYPE OF REPORT...to ?!HF of rich butane/air 3unsen flames. .lso, the rotacion speed and :he oerodic temDeracure fluc:uations of rotacfng ?HF are examined. :’!naily

  18. Combustible Cartridge Case Characterization

    Science.gov (United States)

    1984-02-01

    University (NYU) has resulted in the selection of two cross-linked melamine / formaldehyde acrylic styrene resin systems that can be used in the beater additive... melamine resin Akaradit II stabilizer 20. ABSTRACT (con) Test coupons of combustible cartridge case material were fabricated using these recommended...and agitated for 30 min before the pH was slowly lowered to 3 with p-toluene sulfonic acid. In order to maintain this pH in the felting tank, it was

  19. High Gravity (g) Combustion

    Science.gov (United States)

    2006-02-01

    required thrust-to-weight ratio goals. Shorter residence times in the combustion chamber may reduce the NOx emissions, but the CO and UHC emissions then...Emissions analyzing equipment is available to detect CO, CO2, NOx, O2, and total unburned hydrocarbons ( UHC ) at the combustor exit plane. Emissions... UHC ) emissions along with the CO data, as seen in Fig. 24, shows that Configuration 1 had much higher UHC levels. The reactions from hydrocarbons to

  20. Effect of Hydrogen Addition on Methane HCCI Engine Ignition Timing and Emissions Using a Multi-zone Model

    Science.gov (United States)

    Wang, Zi-han; Wang, Chun-mei; Tang, Hua-xin; Zuo, Cheng-ji; Xu, Hong-ming

    2009-06-01

    Ignition timing control is of great importance in homogeneous charge compression ignition engines. The effect of hydrogen addition on methane combustion was investigated using a CHEMKIN multi-zone model. Results show that hydrogen addition advances ignition timing and enhances peak pressure and temperature. A brief analysis of chemical kinetics of methane blending hydrogen is also performed in order to investigate the scope of its application, and the analysis suggests that OH radical plays an important role in the oxidation. Hydrogen addition increases NOx while decreasing HC and CO emissions. Exhaust gas recirculation (EGR) also advances ignition timing; however, its effects on emissions are generally the opposite. By adjusting the hydrogen addition and EGR rate, the ignition timing can be regulated with a low emission level. Investigation into zones suggests that NOx is mostly formed in core zones while HC and CO mostly originate in the crevice and the quench layer.

  1. Effect of Hydrogen Addition on Methane HCCI Engine Ignition Timing and Emissions Using a Multi-zone Model

    Institute of Scientific and Technical Information of China (English)

    Zi-han Wang; Chun-mei Wang; Hua-xin Tang; Cheng-ji Zuo; Hong-ming Xu

    2009-01-01

    Ignition timing control is of great importance in homogeneous charge compression ignition engines. The effect of hydrogen addition on methane combustion was investigated using a CHEMKIN multi-zone model. Results show that hydrogen addition advances ignition tim-ing and enhances peak pressure and temperature. A brief analysis of chemical kinetics of methane blending hydrogen is also performed in order to investigate the scope of its appli-cation, and the analysis suggests that OH radical plays an important role in the oxidation. Hydrogen addition increases NO while decreasing HC and CO emissions. Exhaust gas recir-culation (EGR) also advances ignition timing; however, its effects on emissions are generally the opposite. By adjusting the hydrogen addition and EGR rate, the ignition timing can be regulated with a low emission level. Investigation into zones suggests that NO is mostly formed in core zones while HC and CO mostly originate in the crevice and the quench layer.

  2. Internal combustion engine using premixed combustion of stratified charges

    Science.gov (United States)

    Marriott, Craig D.; Reitz, Rolf D. (Madison, WI

    2003-12-30

    During a combustion cycle, a first stoichiometrically lean fuel charge is injected well prior to top dead center, preferably during the intake stroke. This first fuel charge is substantially mixed with the combustion chamber air during subsequent motion of the piston towards top dead center. A subsequent fuel charge is then injected prior to top dead center to create a stratified, locally richer mixture (but still leaner than stoichiometric) within the combustion chamber. The locally rich region within the combustion chamber has sufficient fuel density to autoignite, and its self-ignition serves to activate ignition for the lean mixture existing within the remainder of the combustion chamber. Because the mixture within the combustion chamber is overall premixed and relatively lean, NO.sub.x and soot production are significantly diminished.

  3. The Diesel Combustion Collaboratory: Combustion Researchers Collaborating over the Internet

    Energy Technology Data Exchange (ETDEWEB)

    C. M. Pancerella; L. A. Rahn; C. Yang

    2000-02-01

    The Diesel Combustion Collaborator (DCC) is a pilot project to develop and deploy collaborative technologies to combustion researchers distributed throughout the DOE national laboratories, academia, and industry. The result is a problem-solving environment for combustion research. Researchers collaborate over the Internet using DCC tools, which include: a distributed execution management system for running combustion models on widely distributed computers, including supercomputers; web-accessible data archiving capabilities for sharing graphical experimental or modeling data; electronic notebooks and shared workspaces for facilitating collaboration; visualization of combustion data; and video-conferencing and data-conferencing among researchers at remote sites. Security is a key aspect of the collaborative tools. In many cases, the authors have integrated these tools to allow data, including large combustion data sets, to flow seamlessly, for example, from modeling tools to data archives. In this paper the authors describe the work of a larger collaborative effort to design, implement and deploy the DCC.

  4. Internal combustion piston engines

    Energy Technology Data Exchange (ETDEWEB)

    Segaser, C.L.

    1977-07-01

    Current worldwide production of internal combustion piston engines includes many diversified types of designs and a very broad range of sizes. Engine sizes range from a few horsepower in small mobile units to over 40,000 brake horsepower in large stationary and marine units. The key characteristics of internal combustion piston engines considered appropriate for use as prime movers in Integrated Community Energy Systems (ICES) are evaluated. The categories of engines considered include spark-ignition gas engines, compression-ignition oil (diesel) engines, and dual-fuel engines. The engines are evaluated with respect to full-load and part-load performance characteristics, reliability, environmental concerns, estimated 1976 cost data, and current and future status of development. The largest internal combustion piston engines manufactured in the United States range up to 13,540 rated brake horsepower. Future development efforts are anticipated to result in a 20 to 25% increase in brake horsepower without increase in or loss of weight, economy, reliability, or life expectancy, predicated on a simple extension of current development trends.

  5. Issues in waste combustion

    Energy Technology Data Exchange (ETDEWEB)

    Gustavsson, Lennart; Robertson, Kerstin; Tullin, Claes [Swedish National Testing and Research Inst., Boraas (Sweden); Sundquist, Lena; Wrangensten, Lars [AaF-Energikonsult AB, Stockholm (Sweden); Blom, Elisabet [AaF-Processdesign AB, Stockholm (Sweden)

    2003-05-01

    The main purpose of this review is to provide an overview of the state-of-the-art on research and development issues related to waste combustion with relevance for Swedish conditions. The review focuses on co-combustion in grate and fluidised bed furnaces. It is primarily literature searches in relevant databases of scientific publications with to material published after 1995. As a complement, findings published in different report series, have also been included. Since the area covered by this report is very wide, we do not claim to cover the issues included completely and it has not been possitile to evaluate the referred studies in depth. Basic knowledge about combustion issues is not included since such information can be found elsewhere in the literature. Rather, this review should be viewed as an overview of research and development in the waste-to-energy area and as such we hope that it will inspire scientists and others to further work in relevant areas.

  6. Use of the graphical analytic methods of studying the combustion processes in the internal combustion engine combustion chamber on the basis of similarity criterion

    Directory of Open Access Journals (Sweden)

    S. V. Krasheninnikov

    2014-10-01

    Full Text Available The task of improving the economic and ecological parameters of the internal combustion engines remains topical within the frameworks of the modern engine-building technology. Since a combustion engine is a complex system combining such units as an intake manifold, combustion chamber, exhaust manifold, one of directions of the engine development is adjustment of the joint operation of its units. The specified adjustment should better be performed with the use of the so-called integral characteristics. The author means under an integral characteristic the rating plate of a unit (engine containing information about all the possible modes and conditions of its use, specifies the optimal operating range and indicates all the basic values of efficiency – reliability – environmental friendliness at each point of its field. As a rule, integral characteristics are multi-parametric. It is common practice to coordinate the field of such characteristic by similarity criteria determining the unit or engine behavior in whole.

  7. Development of flameless combustion; Desarrollo de la combustion sin flama

    Energy Technology Data Exchange (ETDEWEB)

    Flores Sauceda, M. Leonardo; Cervantes de Gortari, Jaime Gonzalo [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)]. E-mail: 8344afc@prodigy.net.mx; jgonzalo@servidor.unam.mx

    2010-11-15

    The paper intends contribute to global warming mitigation joint effort that develops technologies to capture the CO{sub 2} produced by fossil fuels combustion and to reduce emission of other greenhouse gases like the NO{sub x}. After reviewing existing combustion bibliography is pointed out that (a) touches only partial aspects of the collective system composed by Combustion-Heat transfer process-Environment, whose interactions are our primary interest and (b) most specialists think there is not yet a clearly winning technology for CO{sub 2} capture and storage. In this paper the study of combustion is focused as integrated in the aforementioned collective system where application of flameless combustion, using oxidant preheated in heat regenerators and fluent gas recirculation into combustion chamber plus appropriated heat and mass balances, simultaneously results in energy saving and environmental impact reduction. [Spanish] El trabajo pretende contribuir al esfuerzo conjunto de mitigacion del calentamiento global que aporta tecnologias para capturar el CO{sub 2} producido por la combustion de combustibles fosiles y para disminuir la emision de otros gases invernadero como NOx. De revision bibliografica sobre combustion se concluye que (a) trata aspectos parciales del sistema compuesto por combustion-proceso de trasferencia de calor-ambiente, cuyas interacciones son nuestro principal interes (b) la mayoria de especialistas considera no hay todavia una tecnologia claramente superior a las demas para captura y almacenaje de CO{sub 2}. Se estudia la combustion como parte integrante del mencionado sistema conjunto, donde la aplicacion de combustion sin flama, empleando oxidante precalentado mediante regeneradores de calor y recirculacion de gases efluentes ademas de los balances de masa y energia adecuados, permite tener simultaneamente ahorros energeticos e impacto ambiental reducido.

  8. 均质充量压缩燃烧方式的研究进展及存在问题%Research Development and Main Challenge of Homogeneous Charge Compression Ignition(HCCI)

    Institute of Scientific and Technical Information of China (English)

    汪映; 周龙保; 蒋德明

    2002-01-01

    介绍了均质充量压缩燃烧(HCCI)方式的基本概念,分析了HCCI能实现较高热效率、低NOx排放等优点的机理,论述了制约和影响HCCI方式的各种因素及其当前的研究进展,探讨了HCCI方式面临的主要困难及其解决途径,展望了HCCI方式的应用前景.

  9. Post combustion in converter steelmaking

    Energy Technology Data Exchange (ETDEWEB)

    Oghbasilasie, H.; Holappa, L.

    1997-12-31

    The purpose of this work is to study the fundamentals of post combustion and the effect of different process parameters on the post combustion ratio (PCR) and heat transfer efficiency (HTE) in converter steelmaking process. The PCR and HTE have been determined under normal operating conditions. Trials assessed the effect of lance height, vessel volume, foaming slag and pellet additions on PCR and HTE. Based on enthalpy considerations, post combustion of CO gas is regarded as one of the most effective means of increasing the heat supply to the BOP. The thermodynamic study of gas-metal-slag reactions gives the limiting conditions for post combustion inside the converter reactor. Different process parameters influencing both thermodynamic equilibria and kinetic conditions can greatly affect the post combustion ratio. Different features of converter processes as well smelting reduction processes utilizing post combustion have been reviewed. (orig.) SULA 2 Research Programme; 26 refs.

  10. Sulfur Chemistry in Combustion I

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Glarborg, Peter

    2000-01-01

    of the sulphur compounds in fossil fuels and the possibilities to remove them will be given. Then the combustion of sulphur species and their influence on the combustion chemistry and especially on the CO oxidation and the NOx formation will be described. Finally the in-situ removal of sulphur in the combustion...... process by reaction between SO2 and calcium containing sorbents and the influence on the NOx chemistry will be treated....

  11. OXYGEN ENHANCED COMBUSTION FOR NOx CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    David R. Thompson; Lawrence E. Bool; Jack C. Chen

    2004-04-01

    concept offers substantial savings over SCR and is an economically attractive alternative to purchasing NOx credits or installing other conventional technologies. In conjunction with the development of oxygen based low NOx technology, Praxair also worked on developing the economically enhancing oxygen transport membrane (OTM) technology which is ideally suited for integration with combustion systems to achieve further significant cost reductions and efficiency improvements. This OTM oxygen production technology is based on ceramic mixed conductor membranes that operate at high temperatures and can be operated in a pressure driven mode to separate oxygen with infinite selectivity and high flux. An OTM material was selected and characterized. OTM elements were successfully fabricated. A single tube OTM reactor was designed and assembled. Testing of dense OTM elements was conducted with promising oxygen flux results of 100% of target flux. However, based on current natural gas prices and stand-alone air separation processes, ceramic membranes do not offer an economic advantage for this application. Under a different DOE-NETL Cooperative Agreement, Praxair is continuing to develop oxygen transport membranes for the Advanced Boiler where the economics appear more attractive.

  12. Pulsating combustion - Combustion characteristics and reduction of emissions

    Energy Technology Data Exchange (ETDEWEB)

    Lindholm, Annika

    1999-11-01

    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 NO{sub x} 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 NO{sub x} emitted (referred to stoichiometric

  13. Combustion from basics to applications

    CERN Document Server

    Lackner, Maximilian; Winter, Franz

    2013-01-01

    Combustion, the process of burning, is defined as a chemical reaction between a combustible reactant (the fuel) and an oxidizing agent (such as air) in order to produce heat and in most cases light while new chemical species (e.g., flue gas components) are formed. This book covers a gap on the market by providing a concise introduction to combustion. Most of the other books currently available are targeted towards the experienced users and contain too many details and/or contain knowledge at a fairly high level. This book provides a brief and clear overview of the combustion basics, suitable f

  14. Mathematical Modeling in Combustion Science

    CERN Document Server

    Takeno, Tadao

    1988-01-01

    An important new area of current research in combustion science is reviewed in the contributions to this volume. The complicated phenomena of combustion, such as chemical reactions, heat and mass transfer, and gaseous flows, have so far been studied predominantly by experiment and by phenomenological approaches. But asymptotic analysis and other recent developments are rapidly changing this situation. The contributions in this volume are devoted to mathematical modeling in three areas: high Mach number combustion, complex chemistry and physics, and flame modeling in small scale turbulent flow combustion.

  15. Active Combustion Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Over the past decade, research into active combustion control has yielded impressive results in suppressing thermoacoustic instabilities and widening the...

  16. Active Combustion Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Over the past decade, research into active combustion control has yielded impressive results in suppressing thermoacoustic instabilities and widening the operational...

  17. Basic Aerodynamics of Combustion Chambers,

    Science.gov (United States)

    1981-05-20

    8217, tie imnrulse foree eyuilibr-um c’ the bomd’~ leye - is 173 pv-:irJ p~76vJbK 2sO) IL !-. = Zn pT -- a , bV T. z -,,r y.re C era 3oia * ~~I" onc art-=e...heat by combustion all have very large influences on the capabilities of a combustion chamber. A yellow- colored flame represents diffusion combustion in...the wakes of fuel droplets. Blue- colored flames represent gaseous combustion of evaporated vapors which have already left the fuel droplets. The

  18. Diagnostic for two-mode variable valve activation device

    Energy Technology Data Exchange (ETDEWEB)

    Fedewa, Andrew M

    2014-01-07

    A method is provided for diagnosing a multi-mode valve train device which selectively provides high lift and low lift to a combustion valve of an internal combustion engine having a camshaft phaser actuated by an electric motor. The method includes applying a variable electric current to the electric motor to achieve a desired camshaft phaser operational mode and commanding the multi-mode valve train device to a desired valve train device operational mode selected from a high lift mode and a low lift mode. The method also includes monitoring the variable electric current and calculating a first characteristic of the parameter. The method also includes comparing the calculated first characteristic against a predetermined value of the first characteristic measured when the multi-mode valve train device is known to be in the desired valve train device operational mode.

  19. Combustion Branch Website Development

    Science.gov (United States)

    Bishop, Eric

    2004-01-01

    The NASA combustion branch is a leader in developing and applying combustion science to focused aerospace propulsion systems concepts. It is widely recognized for unique facilities, analytical tools, and personnel. In order to better communicate the outstanding research being done in this Branch to the public and other research organization, a more substantial website was desired. The objective of this project was to build an up-to-date site that reflects current research in a usable and attractive manner. In order to accomplish this, information was requested from all researchers in the Combustion branch, on their professional skills and on the current projects. This information was used to fill in the Personnel and Research sections of the website. A digital camera was used to photograph all personnel and these photographs were included in the personnel section as well. The design of the site was implemented using the latest web standards: xhtml and external css stylesheets. This implementation conforms to the guidelines recommended by the w3c. It also helps to ensure that the web site is accessible by disabled users, and complies with Section 508 Federal legislation (which mandates that all Federal websites be accessible). Graphics for the new site were generated using the gimp (www.gimp.org) an open-source graphics program similar to Adobe Photoshop. Also, all graphics on the site were of a reasonable size (less than 20k, most less than 2k) so that the page would load quickly. Technologies such as Macromedia Flash and Javascript were avoided, as these only function on some clients which have the proper software installed or enabled. The website was tested on different platforms with many different browsers to ensure there were no compatibility issues. The website was tested on windows with MS IE 6, MSIE 5 , Netscape 7, Mozilla and Opera. On a Mac, the site was tested with MS IE 5 , Netscape 7 and Safari.

  20. Alternate fuels; Combustibles alternos

    Energy Technology Data Exchange (ETDEWEB)

    Romero Paredes R, Hernando; Ambriz G, Juan Jose [Universidad Autonoma Metropolitana. Iztapalapa (Mexico)

    2003-07-01

    In the definition and description of alternate fuels we must center ourselves in those technological alternatives that allow to obtain compounds that differ from the traditional ones, in their forms to be obtained. In this article it is tried to give an overview of alternate fuels to the conventional derivatives of petroleum and that allow to have a clear idea on the tendencies of modern investigation and the technological developments that can be implemented in the short term. It is not pretended to include all the tendencies and developments of the present world, but those that can hit in a relatively short term, in accordance with agreed with the average life of conventional fuels. Nevertheless, most of the conversion principles are applicable to the spectrum of carbonaceous or cellulosic materials which are in nature, are cultivated or wastes of organic origin. Thus one will approach them in a successive way, the physical, chemical and biological conversions that can take place in a production process of an alternate fuel or the same direct use of the fuel such as burning the sweepings derived from the forests. [Spanish] En la definicion y descripcion de combustibles alternos nos debemos centrar en aquellas alternativas tecnologicas que permitan obtener compuestos que difieren de los tradicionales, al menos en sus formas de ser obtenidos. En este articulo se pretende dar un panorama de los combustibles alternos a los convencionales derivados del petroleo y que permita tener una idea clara sobre las tendencias de la investigacion moderna y los desarrollos tecnologicos que puedan ser implementados en el corto plazo. No se pretende abarcar todas las tendencias y desarrollos del mundo actual, sino aquellas que pueden impactar en un plazo relativamente corto, acordes con la vida media de los combustibles convencionales. Sin embargo, la mayor parte de los principios de conversion son aplicables al espectro de materiales carbonaceos o celulosicos los cuales se

  1. Combustion Stratification for Naphtha from CI Combustion to PPC

    KAUST Repository

    Vallinayagam, R.

    2017-03-28

    This study demonstrates the combustion stratification from conventional compression ignition (CI) combustion to partially premixed combustion (PPC). Experiments are performed in an optical CI engine at a speed of 1200 rpm for diesel and naphtha (RON = 46). The motored pressure at TDC is maintained at 35 bar and fuelMEP is kept constant at 5.1 bar to account for the difference in fuel properties between naphtha and diesel. Single injection strategy is employed and the fuel is injected at a pressure of 800 bar. Photron FASTCAM SA4 that captures in-cylinder combustion at the rate of 10000 frames per second is employed. The captured high speed video is processed to study the combustion homogeneity based on an algorithm reported in previous studies. Starting from late fuel injection timings, combustion stratification is investigated by advancing the fuel injection timings. For late start of injection (SOI), a direct link between SOI and combustion phasing is noticed. At early SOI, combustion phasing depends on both intake air temperature and SOI. In order to match the combustion phasing (CA50) of diesel, the intake air temperature is increased to 90°C for naphtha. The combustion stratification from CI to PPC is also investigated for various level of dilution by displacing oxygen with nitrogen in the intake. The start of combustion (SOC) was delayed with the increase in dilution and to compensate for this, the intake air temperature is increased. The mixture homogeneity is enhanced for higher dilution due to longer ignition delay. The results show that high speed image is initially blue and then turned yellow, indicating soot formation and oxidation. The luminosity of combustion images decreases with early SOI and increased dilution. The images are processed to generate the level of stratification based on the image intensity. The level of stratification is same for diesel and naphtha at various SOI. When O concentration in the intake is decreased to 17.7% and 14

  2. AIR EMISSIONS FROM SCRAP TIRE COMBUSTION

    Science.gov (United States)

    The report discusses air emissions from two types of scrap tire combustion: uncontrolled and controlled. Uncontrolled sources are open tire fires, which produce many unhealthful products of incomplete combustion and release them directly into the atmosphere. Controlled combustion...

  3. Parametric optimization of a new hybrid pneumatic-combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Higelin, P.; Vasile, I.; Charlet, A.; Chamaillard, Y. [Universite d' Orleans, LME-ESEM, Orleans (France)

    2004-06-01

    Although internal combustion engines display high overall maximum global efficiencies, this potential cannot be fully exploited in automotive applications: in real conditions, the average engine load (and thus efficiency) is quite low and the kinetic energy during a braking phase is lost. One solution to this problem is to switch to a new hybrid pneumatic-combustion engine concept, which is able to store energy in the form of compressed air. This energy can be issued from a braking phase or from a combustion phase at low power. The potential energy from the air tank can then be restored to start the engine, use the stored air to drive the engine as a pneumatic motor at low load or charge the engine at full load. Optimization of the compressed air tank maximum pressure and volume as well as the operating mode switching strategy provides an improvement in terms of fuel economy as high as 31 per cent if combined with engine downsizing. (Author)

  4. Computational investigation on combustion instabilities in a rocket combustor

    Science.gov (United States)

    Yuan, Lei; Shen, Chibing

    2016-10-01

    High frequency combustion instability is viewed as the most challenging task in the development of Liquid Rocket Engines. In this article, results of attempts to capture the self-excited high frequency combustion instability in a rocket combustor are shown. The presence of combustion instability was demonstrated using point measurements, along with Fast Fourier Transform analysis and instantaneous flowfield contours. A baseline case demonstrates a similar wall heat flux profile as the associated experimental case. The acoustic oscillation modes and corresponding frequencies predicted by current simulations are almost the same as the results obtained from classic acoustic analysis. Pressure wave moving back and forth across the combustor was also observed. Then this baseline case was compared against different fuel-oxidizer velocity ratios. It predicts a general trend: the smaller velocity ratio produces larger oscillation amplitudes than the larger one. A possible explanation for the trend was given using the computational results.

  5. Experimental investigations and CFD study of temperature distribution during oscillating combustion in a crucible furnace

    Directory of Open Access Journals (Sweden)

    J. Govardhan, G.V.S. Rao, J. Narasaiah

    2011-09-01

    Full Text Available As part of an investigation few experiments were conducted to study the enhanced heat transfer rate and increased furnace efficiency in a diesel fired crucible furnace with oscillating combustion. The results of experimental investigations of temperature distribution inside the crucible furnace during oscillating combustion are validated with the numerical simulation CFD code. At first pragmatic study of temperature distribution inside a furnace was carried out with conventional mode of combustion at certain conditions and later transient behavior similar to that is conducted with oscillating combustion mode with the same conditions. There found to be enhanced heat transfer rate, reduced processing time and increased furnace efficiency with visibly clean emissions during the oscillating combustion mode than the conventional combustion mode. In the present paper the temperatures inside the furnace at few designated points measured by suitable K type thermo-couples are compared with the CFD code. The geometric models were created in ANSYS and the configuration was an asymmetric one for computational reason. The experimental and numerical investigations produce similar acceptable results. The presented results show that the 3D transient model appeared to be an effective numerical tool for the simulation of the crucible furnace for melting processes.

  6. Numerical Studies on Controlling Gaseous Fuel Combustion by Managing the Combustion Process of Diesel Pilot Dose in a Dual-Fuel Engine

    Directory of Open Access Journals (Sweden)

    Mikulski Maciej

    2015-06-01

    Full Text Available Protection of the environment and counteracting global warming require finding alternative sources of energy. One of the methods of generating energy from environmentally friendly sources is increasing the share of gaseous fuels in the total energy balance. The use of these fuels in compression-ignition (CI engines is difficult due to their relatively high autoignition temperature. One solution for using these fuels in CI engines is operating in a dualfuel mode, where the air and gas mixture is ignited with a liquid fuel dose. In this method, a series of relatively complex chemical processes occur in the engine's combustion chamber, related to the combustion of individual fuel fractions that interact with one another. Analysis of combustion of specific fuels in this type of fuel injection to the engine is difficult due to the fact that combustion of both fuel fractions takes place simultaneously. Simulation experiments can be used to analyse the impact of diesel fuel combustion on gaseous fuel combustion. In this paper, we discuss the results of simulation tests of combustion, based on the proprietary multiphase model of a dual-fuel engine. The results obtained from the simulation allow for analysis of the combustion process of individual fuels separately, which expands the knowledge obtained from experimental tests on the engine.

  7. Manifold methods for methane combustion

    Energy Technology Data Exchange (ETDEWEB)

    Yang, B.; Pope, S.B. [Cornell Univ., Ithaca, NY (United States)

    1995-10-01

    Great progresses have been made in combustion research, especially, the computation of laminar flames and the probability density function (PDF) method in turbulent combustion. For one-dimensional laminar flames, by considering the transport mechanism, the detailed chemical kinetic mechanism and the interactions between these two basic processes, today it is a routine matter to calculate flame velocities, extinction, ignition, temperature, and species distributions from the governing equations. Results are in good agreement with those obtained for experiments. However, for turbulent combustion, because of the complexities of turbulent flow, chemical reactions, and the interaction between them, in the foreseeable future, it is impossible to calculate the combustion flow field by directly integrating the basic governing equations. So averaging and modeling are necessary in turbulent combustion studies. Averaging, on one hand, simplifies turbulent combustion calculations, on the other hand, it introduces the infamous closure problems, especially the closure problem with chemical reaction terms. Since in PDF calculations of turbulent combustion, the averages of the chemical reaction terms can be calculated, PDF methods overcome the closure problem with the reaction terms. It has been shown that the PDF method is a most promising method to calculate turbulent combustion. PDF methods have been successfully employed to calculate laboratory turbulent flames: they can predict phenomena such as super equilibrium radical levels, and local extinction. Because of these advantages, PDF methods are becoming used increasingly in industry combustor codes.

  8. Combustion & Laser Diagnostics Research Complex (CLDRC)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: The Combustion and Laser Diagnostics Research Complex (CLRDC) supports the experimental and computational study of fundamental combustion phenomena to...

  9. An experimental and numerical analysis of the influence of the inlet temperature, equivalence ratio and compression ratio on the HCCI auto-ignition process of Primary Reference Fuels in an engine

    Energy Technology Data Exchange (ETDEWEB)

    Machrafi, Hatim [UPMC Universite Paris 06, LGPPTS, Ecole Nationale Superieure de Chimie de Paris, 11, rue de Pierre et Marie Curie, 75005 Paris (France); UPMC Universite Paris 06, Institut Jean Le Rond D' Alembert (France); Cavadiasa, Simeon [UPMC Universite Paris 06, Institut Jean Le Rond D' Alembert (France)

    2008-11-15

    In order to understand better the auto-ignition process in an HCCI engine, the influence of some important parameters on the auto-ignition is investigated. The inlet temperature, the equivalence ratio and the compression ratio were varied and their influence on the pressure, the heat release and the ignition delays were measured. The inlet temperature was changed from 25 to 70 C and the equivalence ratio from 0.18 to 0.41, while the compression ratio varied from 6 to 13.5. The fuels that were investigated were PRF40 and n-heptane. These three parameters appeared to decrease the ignition delays, with the inlet temperature having the least influence and the compression ratio the most. A previously experimentally validated reduced surrogate mechanism, for mixtures of n-heptane, iso-octane and toluene, has been used to explain observations of the auto-ignition process. The same kinetic mechanism is used to better understand the underlying chemical and physical phenomena that make the influence of a certain parameter change according to the operating conditions. This can be useful for the control of the auto-ignition process in an HCCI engine. (author)

  10. Mission Success for Combustion Science

    Science.gov (United States)

    Weiland, Karen J.

    2004-01-01

    This presentation describes how mission success for combustion experiments has been obtained in previous spaceflight experiments and how it will be obtained for future International Space Station (ISS) experiments. The fluids and combustion facility is a payload planned for the ISS. It is composed of two racks: the fluids Integrated rack and the Combustion INtegrated Rack (CIR). Requirements for the CIR were obtained from a set of combustion basis experiments that served as surrogates for later experiments. The process for experiments that fly on the ISS includes proposal selection, requirements and success criteria definition, science and engineering reviews, mission operations, and postflight operations. By following this process, the microgravity combustion science program has attained success in 41 out of 42 experiments.

  11. Advanced modeling of oxy-fuel combustion of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Chungen Yin

    2011-01-15

    The main goal of this small-scale project is to investigate oxy-combustion of natural gas (NG) through advanced modeling, in which radiation, chemistry and mixing will be reasonably resolved. 1) A state-of-the-art review was given regarding the latest R and D achievements and status of oxy-fuel technology. The modeling and simulation status and achievements in the field of oxy-fuel combustion were also summarized; 2) A computer code in standard c++, using the exponential wide band model (EWBM) to evaluate the emissivity and absorptivity of any gas mixture at any condition, was developed and validated in detail against data in literature. A new, complete, and accurate WSGGM, applicable to both air-fuel and oxy-fuel combustion modeling and applicable to both gray and non-gray calculation, was successfully derived, by using the validated EWBM code as the reference mode. The new WSGGM was implemented in CFD modeling of two different oxy-fuel furnaces, through which its great, unique advantages over the currently most widely used WSGGM were demonstrated. 3) Chemical equilibrium calculations were performed for oxy-NG flame and air-NG flame, in which dissociation effects were considered to different degrees. Remarkable differences in oxy-fuel and air-fuel combustion were revealed, and main intermediate species that play key roles in oxy-fuel flames were identified. Different combustion mechanisms are compared, e.g., the most widely used 2-step global mechanism, refined 4-step global mechanism, a global mechanism developed for oxy-fuel using detailed chemical kinetic modeling (CHEMKIN) as reference. 4) Over 15 CFD simulations were done for oxy-NG combustion, in which radiation, chemistry, mixing, turbulence-chemistry interactions, and so on were thoroughly investigated. Among all the simulations, RANS combined with 2-step and refined 4-step mechanism, RANS combined with CHEMKIN-based new global mechanism for oxy-fuel modeling, and LES combined with different combustion

  12. Liquid rocket combustion instability analysis by CFD methods

    Science.gov (United States)

    Grenda, J. M.; Venkateswaran, S.; Merkle, C. L.

    1991-01-01

    Combustion instability in liquid rocket engines is simulated computationally by using a simple two-parameter model for the combustion response function. The objectives of the study are to assess the capabilities of CFD algorithms for instability studies and to investigate the response to parametric effects such as bombs and distributed combustion. Results indicate that numerical solutions of high accuracy can be obtained if a sufficient number of grid points are used per wavelength of the disturbance. The short-term response to bombs or pulses triggers a large number of modes in the combustor whose faithful resolution requires highly dense grids, although there is evidence that correct long-term solutions can be obtained even if all the short-term frequencies are not resolved. Long-term responses to pulses are shown to decay to the most unstable mode in small amplitude cases, and to exhibit limit cycles in large amplitude cases. Comparison of distributed with concentrated heat release indicates the former is more stable for given values of the combustion response parameters, and that the distributed heat release gives rise to higher frequency disturbances. Wave steepening is observed in the solutions, but its effect is less pronounced in multidimensional waves than in one-dimensional waves.

  13. Analysis of the Transition Time From Air to Oxy-Combustion

    Directory of Open Access Journals (Sweden)

    Lasek Janusz

    2015-03-01

    Full Text Available In this paper some issues of the transition process from air- to oxy-combustion were investigated. Advantages of flexible combustion were described. Flexible combustion tests carried out at four European plants and five plants outside Europe of different scales of process and test parameters were presented. An analysis of the transition time from air to oxy-combustion of different laboratory and pilot scale processes was carried out. The “first-order + dead time” approach was used as a model to describe transition process. Transitional periods between combustion modes and characteristic parameters of the process were determined. The transition time depends not only on the facility’s capacity but also it is impacted by specific operational parameters.

  14. Numerical Simulation Study of Goaf Methane Drainage and Spontaneous Combustion Coupling

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to study the coupling problem between methane drainage and spontaneous combustion of residual coal in the collapsed zone after mining ignitable coal seams with high methane, we have analyzed the effects of different methane drainage modes on spontaneous combustion of residual coal through numerical simulation.The results show that deep and large flux methane drainage modes increases the air leakage from work faces to the goaf and formed new spontaneous combustion zones induced by drainage near vents, which increases the risk of self-ignition of coal-reducing the self-ignition period and enlarging the scale of self-ignition.The spontaneous upstream combustion oxidation of the main fire zone can be suppressed when both drainage and nitrogen injection were adopted.Our research results provide an effective technical measure and theoretical basis to determine the best methane drainage scheme and drainage parameters.

  15. TOXIC SUBSTANCES FROM COAL COMBUSTION-A COMPREHENSIVE ASSESSMENT

    Energy Technology Data Exchange (ETDEWEB)

    C.L. Senior; F. Huggins; G.P. Huffman; N. Shah; N. Yap; J.O.L. Wendt; W. Seames; M.R. Ames; A.F. Sarofim; S. Swenson; J.S. Lighty; A. Kolker; R. Finkelman; C.A. Palmer; S.J. Mroczkowski; J.J. Helble; R. Mamani-Paco; R. Sterling; G. Dunham; S. Miller

    2001-06-30

    The Clean Air Act Amendments of 1990 identify a number of hazardous air pollutants (HAPs) as candidates for regulation. Should regulations be imposed on HAP emissions from coal-fired power plants, a sound understanding of the fundamental principles controlling the formation and partitioning of toxic species during coal combustion will be needed. With support from the National Energy Technology Laboratory (NETL), the Electric Power Research Institute, and VTT (Finland), Physical Sciences Inc. (PSI) has teamed with researchers from USGS, MIT, the University of Arizona (UA), the University of Kentucky (UK), the University of Connecticut (UC), the University of Utah (UU) and the University of North Dakota Energy and Environmental Research Center (EERC) to develop a broadly applicable emissions model useful to regulators and utility planners. The new Toxics Partitioning Engineering Model (ToPEM) will be applicable to all combustion conditions including new fuels and coal blends, low-NOx combustion systems, and new power generation plants. Development of ToPEM will be based on PSI's existing Engineering Model for Ash Formation (EMAF). The work discussed in this report covers the Phase II program. Five coals were studied (three in Phase I and two new ones in Phase II). In this work UK has used XAFS and Moessbauer spectroscopies to characterize elements in project coals. For coals, the principal use was to supply direct information about certain hazardous and other key elements (iron) to complement the more complete indirect investigation of elemental modes of occurrence being carried out by colleagues at USGS. Iterative selective leaching using ammonium acetate, HCl, HF, and HNO3, used in conjunction with mineral identification/quantification, and microanalysis of individual mineral grains, has allowed USGS to delineate modes of occurrence for 44 elements. The Phase II coals show rank-dependent systematic differences in trace-element modes of occurrence. The work at

  16. TOXIC SUBSTANCES FROM COAL COMBUSTION-A COMPREHENSIVE ASSESSMENT

    Energy Technology Data Exchange (ETDEWEB)

    C.L. Senior; F. Huggins; G.P. Huffman; N. Shah; N. Yap; J.O.L. Wendt; W. Seames; M.R. Ames; A.F. Sarofim; S. Swenson; J.S. Lighty; A. Kolker; R. Finkelman; C.A. Palmer; S.J. Mroczkowski; J.J. Helble; R. Mamani-Paco; R. Sterling; G. Dunham; S. Miller

    2001-06-30

    The Clean Air Act Amendments of 1990 identify a number of hazardous air pollutants (HAPs) as candidates for regulation. Should regulations be imposed on HAP emissions from coal-fired power plants, a sound understanding of the fundamental principles controlling the formation and partitioning of toxic species during coal combustion will be needed. With support from the National Energy Technology Laboratory (NETL), the Electric Power Research Institute, and VTT (Finland), Physical Sciences Inc. (PSI) has teamed with researchers from USGS, MIT, the University of Arizona (UA), the University of Kentucky (UK), the University of Connecticut (UC), the University of Utah (UU) and the University of North Dakota Energy and Environmental Research Center (EERC) to develop a broadly applicable emissions model useful to regulators and utility planners. The new Toxics Partitioning Engineering Model (ToPEM) will be applicable to all combustion conditions including new fuels and coal blends, low-NOx combustion systems, and new power generation plants. Development of ToPEM will be based on PSI's existing Engineering Model for Ash Formation (EMAF). The work discussed in this report covers the Phase II program. Five coals were studied (three in Phase I and two new ones in Phase II). In this work UK has used XAFS and Moessbauer spectroscopies to characterize elements in project coals. For coals, the principal use was to supply direct information about certain hazardous and other key elements (iron) to complement the more complete indirect investigation of elemental modes of occurrence being carried out by colleagues at USGS. Iterative selective leaching using ammonium acetate, HCl, HF, and HNO3, used in conjunction with mineral identification/quantification, and microanalysis of individual mineral grains, has allowed USGS to delineate modes of occurrence for 44 elements. The Phase II coals show rank-dependent systematic differences in trace-element modes of occurrence. The work at

  17. The first turbulent combustion

    CERN Document Server

    Gibson, C H

    2005-01-01

    The first turbulent combustion arises in a hot big bang cosmological model Gibson (2004) where nonlinear exothermic turbulence permitted by quantum mechanics, general relativity, multidimensional superstring theory, and fluid mechanics cascades from Planck to strong force freeze out scales with gravity balancing turbulent inertial-vortex forces. Interactions between Planck scale spinning and non-spinning black holes produce high Reynolds number turbulence and temperature mixing with huge Reynolds stresses driving the rapid inflation of space. Kolmogorovian turbulent temperature patterns are fossilized as strong-force exponential inflation stretches them beyond the scale of causal connection ct where c is light speed and t is time. Fossil temperature turbulence patterns seed nucleosynthesis, and then hydro-gravitational structure formation in the plasma epoch, Gibson (1996, 2000). Evidence about formation mechanisms is preserved by cosmic microwave background temperature anisotropies. CMB spectra indicate hydr...

  18. USGS TOXIC SUBSTANCES FROM COAL COMBUSTION -- FORMS OF OCCURRENCE ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Allan Kolker; Stanley J. Mroczkowski; Curtis A. Palmer; Robert B. Finkelman

    1999-04-01

    Detailed information on trace-element modes of occurrence in coal is essential to understanding and predicting trace-element transformations taking place during coal combustion. The USGS has developed quantitative and semi-quantitative methods for determining the mode of occurrence of trace elements in coal. This information is needed to generate predictive models for trace-element behavior, the ultimate goal of DOE contract DE-AC22-95PC95101 ``Toxic Substances From Coal Combustion--A Comprehensive Assessment'' awarded to PSI, Inc. USGS activities in support of this contract have a direct bearing on the predictive equations being developed as the primary product of the PSI program.

  19. Air supply system for an internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Eftink, A.

    1992-06-11

    The present invention describes a system for supplying the primary combustion air to a reciprocating piston internal combustion engine including a trochoidal chamber air pump having a pair of pumping chambers interposed between an air intake and each of the cylinders of the engine. Each pumping chamber has an air inlet connected to an air intake, and an air outlet that is connected to the cylinders. In a two-cycle mode of operation, each pumping chamber outlet is connected to one engine cylinder. In a four-cycle mode of operation, each pumping chamber outlet is connected to a pair of cylinders to supply air during the intake stroke. The input shaft of the trochoidal chamber air pump is driven by, and may be connected to, the crankshaft of the engine so as to rate on a 1:1 ratio. (author)

  20. Filtration combustion: Smoldering and SHS

    Science.gov (United States)

    Matkowsky, Bernard J.

    1995-01-01

    Smolder waves and SHS (self-propagating high-temperature synthesis) waves are both examples of combustion waves propagating in porous media. When delivery of reactants through the pores to the reaction site is an important aspect of the process, it is referred to as filtration combustion. The two types of filtration combustion have a similar mathematical formulation, describing the ignition, propagation and extinction of combustion waves in porous media. The goal in each case, however, is different. In smoldering the desired goal is to prevent propagation, whereas in SHS the goal is to insure propagation of the combustion wave, leading to the synthesis of desired products. In addition, the scales in the two areas of application may well differ. For example, smoldering generally occurs at a relatively low temperature and with a smaller propagation velocity than SHS filtration combustion waves. Nevertheless, the two areas of application have much in common, so that mechanisms learned about in one application can be used to advantage in the other. In this paper we discuss recent results in the areas of filtration combustion.

  1. Combustion Properties of Straw Briquettes

    Directory of Open Access Journals (Sweden)

    Zhao Qing-ling

    2013-05-01

    Full Text Available The low bulk density of straw is one of the major barriers, which blocks the collection, handling, transportation and storage. Densification of biomass into briquettes/pellets is a suitable method of increasing the bulk density of biomass. Yet in the process, a tremendous amount of air is ejected from biomass grind, which brings substantial specific variation including combustion property. Among them, combustion property is critical for proper design and operation of burning facilities. Therefore, a series of tests about combustion properties of 75mm diameter corn briquettes were done. First, the combustion process (ignition, full flaming and glowing phases., precipitation of tar were investigated by a heating stove, then, Some ash sample from the muffle burner was subjected to an ash melting characteristic test. The results show the combustion of briquettes takes more time than that of raw straw from ignition to complete combustion; in order to meet complete combustion in a short time, the raw straw needs more supply air volume than briquettes under the same α value; the temperature of furnace chamber should been controlled under 900°C, which help to reduce the dark smoke, tar and slag.

  2. Cyclic Combustion Variations in Dual Fuel Partially Premixed Pilot-Ignited Natural Gas Engines

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, K. K. [Mississippi State Univ., MS (United States). Dept. of Mechanical Engineering; Krishnan, S. R. [Mississippi State Univ., MS (United States). Dept. of Mechanical Engineering; Qi, Y. [Caterpillar, Inc., Peoria, IL (United States)

    2012-05-09

    Dual fuel pilot ignited natural gas engines are identified as an efficient and viable alternative to conventional diesel engines. This paper examines cyclic combustion fluctuations in conventional dual fuel and in dual fuel partially premixed low temperature combustion (LTC). Conventional dual fueling with 95% (energy basis) natural gas (NG) substitution reduces NOx emissions by almost 90%t relative to straight diesel operation; however, this is accompanied by 98% increase in HC emissions, 10 percentage points reduction in fuel conversion efficiency (FCE) and 12 percentage points increase in COVimep. Dual fuel LTC is achieved by injection of a small amount of diesel fuel (2-3 percent on an energy basis) to ignite a premixed natural gas₋air mixture to attain very low NOx emissions (less than 0.2 g/kWh). Cyclic variations in both combustion modes were analyzed by observing the cyclic fluctuations in start of combustion (SOC), peak cylinder pressures (Pmax), combustion phasing (Ca50), and the separation between the diesel injection event and Ca50 (termed "relative combustion phasing" ). For conventional dual fueling, as % NG increases, Pmax decreases, SOC and Ca50 are delayed, and cyclic variations increase. For dual fuel LTC, as diesel injection timing is advanced from 20° to 60° BTDC, the relative combustion phasing is identified as an important combustion parameter along with SoC, Pmax, and CaPmax. For both combustion modes, cyclic variations were characterized by alternating slow and fast burn cycles, especially at high %NG and advanced injection timings. Finally, heat release return maps were analyzed to demonstrate thermal management strategies as an effective tool to mitigate cyclic combustion variations, especially in dual fuel LTC.

  3. Catalytic Combustion of Gasified Waste

    Energy Technology Data Exchange (ETDEWEB)

    Kusar, Henrik

    2003-09-01

    This thesis concerns catalytic combustion for gas turbine application using a low heating-value (LHV) gas, derived from gasified waste. The main research in catalytic combustion focuses on methane as fuel, but an increasing interest is directed towards catalytic combustion of LHV fuels. This thesis shows that it is possible to catalytically combust a LHV gas and to oxidize fuel-bound nitrogen (NH{sub 3}) directly into N{sub 2} without forming NO{sub x} The first part of the thesis gives a background to the system. It defines waste, shortly describes gasification and more thoroughly catalytic combustion. The second part of the present thesis, paper I, concerns the development and testing of potential catalysts for catalytic combustion of LHV gases. The objective of this work was to investigate the possibility to use a stable metal oxide instead of noble metals as ignition catalyst and at the same time reduce the formation of NO{sub x} In paper II pilot-scale tests were carried out to prove the potential of catalytic combustion using real gasified waste and to compare with the results obtained in laboratory scale using a synthetic gas simulating gasified waste. In paper III, selective catalytic oxidation for decreasing the NO{sub x} formation from fuel-bound nitrogen was examined using two different approaches: fuel-lean and fuel-rich conditions. Finally, the last part of the thesis deals with deactivation of catalysts. The various deactivation processes which may affect high-temperature catalytic combustion are reviewed in paper IV. In paper V the poisoning effect of low amounts of sulfur was studied; various metal oxides as well as supported palladium and platinum catalysts were used as catalysts for combustion of a synthetic gas. In conclusion, with the results obtained in this thesis it would be possible to compose a working catalytic system for gas turbine application using a LHV gas.

  4. On Lean Turbulent Combustion Modeling

    Directory of Open Access Journals (Sweden)

    Constantin LEVENTIU

    2014-06-01

    Full Text Available This paper investigates a lean methane-air flame with different chemical reaction mechanisms, for laminar and turbulent combustion, approached as one and bi-dimensional problem. The numerical results obtained with Cantera and Ansys Fluent software are compared with experimental data obtained at CORIA Institute, France. First, for laminar combustion, the burn temperature is very well approximated for all chemical mechanisms, however major differences appear in the evaluation of the flame front thickness. Next, the analysis of turbulence-combustion interaction shows that the numerical predictions are suficiently accurate for small and moderate turbulence intensity.

  5. Regulation possibilities of biomass combustion

    Science.gov (United States)

    Suzdalenko, Vera; Gedrovics, Martins; Zake, Maija; Barmina, Inesa

    2012-11-01

    The focus of the recent experimental research is to analyze the regulation possibilities of biomass combustion. Three possibilities were chosen as part of this research: a) biomass cofiring with propane, b) swirling flow with re-circulation zone, and c) use of a permanent magnet. The aim of the research is to provide stable, controllable and effective biomass combustion with minimum emissions. The special pilot device was created where biomass can be combusted separately and co-fired with propane. Wood pellets were used during the experiments.

  6. Combustion-gas recirculation system

    Science.gov (United States)

    Baldwin, Darryl Dean

    2007-10-09

    A combustion-gas recirculation system has a mixing chamber with a mixing-chamber inlet and a mixing-chamber outlet. The combustion-gas recirculation system may further include a duct connected to the mixing-chamber inlet. Additionally, the combustion-gas recirculation system may include an open inlet channel with a solid outer wall. The open inlet channel may extend into the mixing chamber such that an end of the open inlet channel is disposed between the mixing-chamber inlet and the mixing-chamber outlet. Furthermore, air within the open inlet channel may be at a pressure near or below atmospheric pressure.

  7. Evaluation of reduced chemical kinetic mechanisms used for modeling mild combustion for natural gas

    Directory of Open Access Journals (Sweden)

    Hamdi Mohamed

    2009-01-01

    Full Text Available A numerical and parametric study was performed to evaluate the potential of reduced chemistry mechanisms to model natural gas chemistry including NOx chemistry under mild combustion mode. Two reduced mechanisms, 5-step and 9-step, were tested against the GRI-Mech3.0 by comparing key species, such as NOx, CO2 and CO, and gas temperature predictions in idealized reactors codes under mild combustion conditions. It is thus concluded that the 9-step mechanism appears to be a promising reduced mechanism that can be used in multi-dimensional codes for modeling mild combustion of natural gas.

  8. THE COMBUSTION ACTION VERIFICATION AND ESTIMATE OF COMBUSTION EFFICIENCY IN AVIATION GAS#TURBINE ENGINE COMBUSTION CHAMBERS

    OpenAIRE

    2011-01-01

    Verification results of combustion action simulating and estimate of calculation combustion efficiency that was given by simulating were shown. Mathematical model and its assumption are described. Execution calculations method was shown. Results of simulating are shown; their comparative analyses with results of experiment were executed. Accuracy of combustion action mathematical modeling by combustion efficiency in model with oneand two-stage reactions of combustion was estimated. The infere...

  9. Measures for a quality combustion (combustion chamber exit and downstream); Mesures pour une combustion de qualite (sortie de chambre de combustion et en aval)

    Energy Technology Data Exchange (ETDEWEB)

    Epinat, G. [APAVE Lyonnaise, 69 (France)

    1996-12-31

    After a review of the different pollutants related to the various types of stationary and mobile combustion processes (stoichiometric, reducing and oxidizing combustion), measures and analyses than may be used to ensure the quality and efficiency of combustion processes are reviewed: opacimeters, UV analyzers, etc. The regulation and control equipment for combustion systems are then listed, according to the generator capacity level

  10. Computational Modeling of Turbulent Spray Combustion

    NARCIS (Netherlands)

    Ma, L.

    2016-01-01

    The objective of the research presented in this thesis is development and validation of predictive models or modeling approaches of liquid fuel combustion (spray combustion) in hot-diluted environments, known as flameless combustion or MILD combustion. The goal is to combine good physical insight,

  11. Computational Modeling of Turbulent Spray Combustion

    NARCIS (Netherlands)

    Ma, L.

    2016-01-01

    The objective of the research presented in this thesis is development and validation of predictive models or modeling approaches of liquid fuel combustion (spray combustion) in hot-diluted environments, known as flameless combustion or MILD combustion. The goal is to combine good physical insight, a

  12. Combustion Process Modelling and Control

    Directory of Open Access Journals (Sweden)

    Vladimír Maduda

    2007-10-01

    Full Text Available This paper deals with realization of combustion control system on programmable logic controllers. Control system design is based on analysis of the current state of combustion control systems in technological device of raw material processing area. Control system design is composed of two subsystems. First subsystem is represented by software system for measured data processing and for data processing from simulation of the combustion mathematical model. Outputs are parameters for setting of controller algorithms. Second subsystem consists from programme modules. The programme module is presented by specific control algorithm, for example proportional regulation, programmed proportional regulation, proportional regulation with correction on the oxygen in waste gas, and so on. According to the specific combustion control requirements it is possible built-up concrete control system by programme modules. The programme modules were programmed by Automation studio that is used for development, debugging and testing software for B&R controllers.

  13. Putting combustion optimization to work

    Energy Technology Data Exchange (ETDEWEB)

    Spring, N.

    2009-05-15

    New plants and plants that are retrofitting can benefit from combustion optimization. Boiler tuning and optimization can complement each other. The continuous emissions monitoring system CEMS, and tunable diode laser absorption spectroscopy TDLAS can be used for optimisation. NeuCO's CombustionOpt neural network software can determine optimal fuel and air set points. Babcock and Wilcox Power Generation Group Inc's Flame Doctor can be used in conjunction with other systems to diagnose and correct coal-fired burner performance. The four units of the Colstrip power plant in Colstrips, Montana were recently fitted with combustion optimization systems based on advanced model predictive multi variable controls (MPCs), ABB's Predict & Control tool. Unit 4 of Tampa Electric's Big Bend plant in Florida is fitted with Emerson's SmartProcess fuzzy neural model based combustion optimisation system. 1 photo.

  14. Flameless Combustion for Gas Turbines

    Science.gov (United States)

    Gutmark, Ephraim; Li, Guoqiang; Overman, Nick; Cornwell, Michael; Stankovic, Dragan; Fuchs, Laszlo; Milosavljevic, Vladimir

    2006-11-01

    An experimental study of a novel flameless combustor for gas turbine engines is presented. Flameless combustion is characterized by distributed flame and even temperature distribution for high preheat air temperature and large amount of recirculating low oxygen exhaust gases. Extremely low emissions of NOx, CO, and UHC are reported. Measurements of the flame chemiluminescence, CO and NOx emissions, acoustic pressure, temperature and velocity fields as a function of the preheat temperature, inlet air mass flow rate, exhaust nozzle contraction ratio, and combustor chamber diameter are described. The data indicate that larger pressure drop promotes flameless combustion and low NOx emissions at the same flame temperature. High preheated temperature and flow rates also help in forming stable combustion and therefore are favorable for flameless combustion.

  15. An experimental and numerical investigation on the influence of external gas recirculation on the HCCI autoignition process in an engine: Thermal, diluting, and chemical effects

    Energy Technology Data Exchange (ETDEWEB)

    Machrafi, Hatim; Cavadias, Simeon [UPMC Universite Paris 06, LGPPTS, Ecole Nationale Superieure de Chimie de Paris, 11, rue de Pierre et Marie Curie, 75005 Paris (France); UPMC Universite Paris 06, FRT, Institut Jean Le Rond D' Alembert, 2, place de la Gare de Ceinture, 78210 St Cyr l' Ecole (France); Guibert, Philippe [UPMC Universite Paris 06, FRT, Institut Jean Le Rond D' Alembert, 2, place de la Gare de Ceinture, 78210 St Cyr l' Ecole (France)

    2008-11-15

    In order to contribute to the solution of controlling the autoignition in a homogeneous charge compression ignition (HCCI) engine, parameters linked to external gas recirculation (EGR) seem to be of particular interest. Experiments performed with EGR present some difficulties in interpreting results using only the diluting and thermal aspect of EGR. Lately, the chemical aspect of EGR is taken more into consideration, because this aspect causes a complex interaction with the dilution and thermal aspects of EGR. This paper studies the influence of EGR on the autoignition process and particularly the chemical aspect of EGR. The diluents present in EGR are simulated by N{sub 2} and CO{sub 2}, with dilution factors going from 0 to 46 vol%. For the chemically active species that could be present in EGR, the species CO, NO, and CH{sub 2}O are used. The initial concentration in the inlet mixture of CO and NO is varied between 0 and 170 ppm, while that of CH{sub 2}O alters between 0 and 1400 ppm. For the investigation of the effect of the chemical species on the autoignition, a fixed dilution factor of 23 vol% and a fixed EGR temperature of 70 C are maintained. The inlet temperature is held at 70 C, the equivalence ratios between 0.29 and 0.41, and the compression ratio at 10.2. The fuels used for the autoignition are n-heptane and PRF40. It appeared that CO, in the investigated domain, did not influence the ignition delays, while NO had two different effects. At concentrations up until 45 ppm, NO advanced the ignition delays for the PRF40 and at higher concentrations, the ignition delayed. The influence of NO on the autoignition of n-heptane seemed to be insignificant, probably due to the higher burn rate of n-heptane. CH{sub 2}O seemed to delay the ignition. The results suggested that especially the formation of OH radicals or their consumption by the chemical additives determines how the reactivity of the autoignition changed. (author)

  16. Combustion of boron containing compositions

    Energy Technology Data Exchange (ETDEWEB)

    Frolov, Y.; Pivkina, A. [Institute of Chemical Physics, Russian Academy of Science, Moscow (Russian Federation)

    1996-12-31

    Boron is one of the most energetic components for explosives, propellants and for heterogeneous condensed systems in common. The combustion process of mixtures of boron with different oxidizers was studied. The burning rate, concentration combustion limits, the agglomeration and dispersion processes during reaction wave propagation were analysed in the respect of the percolation theory. The linear dependence of the burning rate on the contact surface value was demonstrated. The percolative model for the experimental results explanation is proposed. (authors) 5 refs.

  17. Smoldering Combustion Experiments in Microgravity

    Science.gov (United States)

    Walther, David C.; Fernandez-Pello, A. Carlos; Urban, David L.

    1997-01-01

    The Microgravity Smoldering Combustion (MSC) experiment is part of a study of the smolder characteristics of porous combustible materials in a microgravity environment. Smoldering is a non-flaming form of combustion that takes place in the interior of porous materials and takes place in a number of processes ranging from smoldering of porous insulation materials to high temperature synthesis of metals. The objective of the study is to provide a better understanding of the controlling mechanisms of smolder, both in microgravity and normal-gravity. As with many forms of combustion, gravity affects the availability of oxidizer and transport of heat, and therefore the rate of combustion. Microgravity smolder experiments, in both a quiescent oxidizing environment, and in a forced oxidizing flow have been conducted aboard the NASA Space Shuttle (STS-69 and STS-77 missions) to determine the effect of the ambient oxygen concentration and oxidizer forced flow velocity on smolder combustion in microgravity. The experimental apparatus is contained within the NASA Get Away Special Canister (GAS-CAN) Payload. These two sets of experiments investigate the propagation of smolder along the polyurethane foam sample under both diffusion driven and forced flow driven smoldering. The results of the microgravity experiments are compared with identical ones carried out in normal gravity, and are used to verify present theories of smolder combustion. The results of this study will provide new insights into the smoldering combustion process. Thermocouple histories show that the microgravity smolder reaction temperatures (Ts) and propagation velocities (Us) lie between those of identical normal-gravity upward and downward tests. These observations indicate the effect of buoyancy on the transport of oxidizer to the reaction front.

  18. Effects of ethanol on combustion and emissions of a gasoline engine operating with different combustion modes

    OpenAIRE

    Ojapah, MM; Zhao, H.; Zhang, Y.

    2016-01-01

    The introduction of fuel economy and CO2 emission legislations for passenger cars in many countries and regions has spurred the research and development of more efficient gasoline engines. The pumping loss at part-load operations is a major factor for the higher fuel consumption of spark ignition (SI) gasoline engines than the diesel engines. Various approaches have been identified to reduce the pumping loss at part-load operations, leading to improved fuel economy, including Early Intake Val...

  19. Fundamentals of Aerodynamic-Flow and Combustion Control by Plasmas

    Science.gov (United States)

    2010-05-14

    decreased gas pressure [1]. Here we propose a system which can lead to ignition under conditions of automotive engines , including HCCI , gas...Discharge Plasma Richard Whalley & Kwing-So Choi Faculty of Engineering , University of Nottingham University Park, Nottingham NG7 2RD, UK... engines , and various designs of electric propulsion systems for satellites. As computer capabilities improve rapidly, the ability to model non

  20. Studying the specific features pertinent to combustion of chars obtained from coals having different degrees of metamorphism and biomass chars

    Science.gov (United States)

    Bestsennyi, I. V.; Shchudlo, T. S.; Dunaevskaya, N. I.; Topal, A. I.

    2013-12-01

    Better conditions for igniting low-reaction coal (anthracite) can be obtained, higher fuel burnout ratio can be achieved, and the problem of shortage of a certain grade of coal can be solved by firing coal mixtures and by combusting coal jointly with solid biomass in coal-fired boilers. Results from studying the synergetic effect that had been revealed previously during the combustion of coal mixtures in flames are presented. A similar effect was also obtained during joint combustion of coal and wood in a flame. The kinetics pertinent to combustion of char mixtures obtained from coals characterized by different degrees of metamorphism and the kinetics pertinent to combustion of wood chars were studied on the RSK-1D laboratory setup. It was found from the experiments that the combustion rate of char mixtures obtained from coals having close degrees of metamorphism is equal to the value determined as a weighted mean rate with respect to the content of carbon. The combustion rate of char mixtures obtained from coals having essentially different degrees of metamorphism is close to the combustion rate of more reactive coal initially in the process and to the combustion rate of less reactive coal at the end of the process. A dependence of the specific burnout rate of carbon contained in the char of two wood fractions on reciprocal temperature in the range 663—833 K is obtained. The combustion mode of an experimental sample is determined together with the reaction rate constant and activation energy.

  1. 汽化效应对燃气蒸汽式弹射气液两相流场的影响%Influence of vaporization effect on gas-liquid two-phase flow field of ejection in combustion gas and vapor mode

    Institute of Scientific and Technical Information of China (English)

    刘伯伟; 姜毅

    2014-01-01

    为研究汽化效应对燃气蒸汽式弹射发射过程的影响,建立了某型集中注水式弹射装置的二维轴对称模型,利用耦合Mixture多相流模型与组分输运模型求解发射过程中的气液两相冻结流场,通过向守恒方程添加源项的方式引入液态水的汽化模型,利用Soave-Redlich-Kwong真实气体模型模拟水蒸汽的状态变化,得到了发射过程中液态水的流型及汽化过程,通过两种工况与试验结果的比较,验证了仿真结果的可靠性。结果表明,与不考虑汽化效应相比,考虑汽化效应使仿真流场的最大平均温度降低524 K,弹托底部最大平均温度降低223 K,考虑汽化效应得到的内弹道过程与试验结果更加一致,对该类问题的仿真与改进具有指导意义。%To study the influence of vaporization effect on launching process of ejection in combustion gas and vapor mode,2D axisymmetric model of an ejection device with water injection in block was established. The coupling of mixture multiphase model and species transport model was used to solve gas-liquid two-phase frozen flow field. A vaporization model of water was introduced by adding source terms to conservation equations. Soave-Redlich-Kwong real gas model was used to simulate the state change of va-por. The flow pattern and vaporization process of water were obtained. By comparison of two conditions and experimental results,the reliability of simulation results was verified. The research shows,compared with the condition without considering vaporization effect, the maximum average temperature of flow field with considering vaporization effect reduces 524 K,and the maximum average temper-ature nearing sabot reduces 223 K. Interior ballistic process with vaporization effect is more identical to the experimental results, which has guiding significance to the simulation and improvement of this kind of problems.

  2. Rotary internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Witkowski, J.

    1989-12-05

    This patent describes an internal combustion engine assembly. It includes: a central rotor means formed with at least one peripheral fuel cavity. The cavity having a first surface defining a thrust surface and a second surface defining a contoured surface; a housing means enclosing the rotor and having an internal wall encircling the rotor. The internal wall being intercepted by at least two recesses defining cylinder means. The housing means and the rotor means being relatively rotatable; piston means individual to each the cylinder means and reciprocable therein; each piton means having a working face complementary to aid contoured surface; and power means for urging the working face into intimate areal contact with the contoured surface to create a first seal means. The housing means having at lest one fuel inlet port, at least one fuel ignition means and at least one exhaust port whereby during the course of a revolution of the rotor means relative to the housing means, the first seal means, the power means, the respective ports, the ignition means and the fuel cavity cooperate to develop fuel compression, fuel ignition and exhaust functions.

  3. Internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Laskaris, M.A.; Broitman, K.; Natale, S.E.

    1991-08-27

    This patent describes improvement in a two-stroke internal combustion engine adapted to run on a diesel or a kerosene type of fuel, and including a piston connected to the crankshaft of the engine to move within a cylinder through a first stroke from a top dead center position to a bottom dead center position and through a second stroke from the bottom dead center position back to the top dead center position. The improvement comprises: means providing a cylinder head at the top end of the engine cylinder in the shape of an open bowl having a generally cup-shaped configuration including a sidewall portion, a spark plug positioned centrally within the bowl at the top end of the cylinder, and means for injecting fuel into the top end of the engine cylinder at a location between the spark plug and the sidewall portion, the fuel injecting means including an injection nozzle having a plurality of nozzle openings therein, the nozzle openings being constructed and arranged to discharge a plurality of plume-like sprays into the top end of the cylinder at a location within the bowl, two of the sprays being directed from the nozzle to diverge and pass along opposite sides of the spark plug, and additional sprays being directed from the nozzle against the sidewall portion or the cylinder head to be deflected therefrom back toward the piston and the spark plug to thereby form a cloud of fuel over the spark plug for good ignition.

  4. Clean coal technologies handbook: fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    1999-01-01

    The term fluidisation is used to describe a type or mode of contact between fluids and granular solids, in such a way that solid particles appear as suspended in the moving fluid. The fluid moves vertically upwards through the bed formed by the particles. The reason to use the word fluidisation is that, when a solid particles bed is treated in the above mentioned way, it acquires an aspect very similar to that of a boiling liquid, and it has properties similar to those of a liquid. Thus, a bed in such conditions is called fluidised bed; the name fluidisation is reserved to the operation required to reach such state. This contacting method shows a number of fetaures which make it very useful to carry on many important processes in the fields of Chemical Engineering and Extractive Metallurgy; for that reason it has been studied very deeply in the last year, on the theoretical aspect and on its practical applications as well. Going back in time to the origin of the fluidisation, as it is known at present, we find that is started to develop at the beginning of the 1940's. The first application of fluidisation is described by Agricola in his famous book De re metallica, which must have been written in XVI the century. In this book there is the mention of the concentration of metallic ores by means of an expansion of the bed produced by a vertical upwards water flow which passes through the layer of rough mineral. From the beginning of its development, fluidisation has had many applications, such as water clarification, pulverised coal gasification, catalytic cracking chemical processes, drying of pulverulent materials and incineration of solid residues, among others. Until the end of 1950 the application was not used to coal combustion; it has strongly development after the energy crisis. Starting in the 1970's a great effort at world level is being made to develop the technology of Fluidised Bed Combustion (FBC), pushed on by two main reasons.: 1) Reduction

  5. DOE Project 18546, AOP Task 1.1, Fuel Effects on Advanced Combustion Engines

    Energy Technology Data Exchange (ETDEWEB)

    Bunting, Bruce G [ORNL; Bunce, Michael [ORNL

    2012-01-01

    Research in 2011 was focused on diesel range fuels and diesel combustion and fuels evaluated in 2011 included a series of oxygenated biofuels fuels from University of Maine, oxygenated fuel compounds representing materials which could be made from sewage, oxygenated marine diesel fuels for low emissions, and a new series of FACE fuel surrogates and FACE fuels with detailed exhaust chemistry and particulate size measurements. Fuels obtained in late 2011, which will be evaluated in 2012, include a series of oil shale derived fuels from PNNL, green diesel fuel (hydrotreated vegetable oil) from UOP, University of Maine cellulosic biofuel (levulene), and pyrolysis derived fuels from UOP pyrolysis oil, upgraded at University of Georgia. We were able to demonstrate, through a project with University of Wisconsin, that a hybrid strategy for fuel surrogates provided both accurate and rapid CFD combustion modeling for diesel HCCI. In this strategy, high molecular weight compounds are used to more accurately represent physical processes and smaller molecular weight compounds are used for chemistry to speed chemical calculations. We conducted a small collaboration with sp3H, a French company developing an on-board fuel quality sensor based on near infrared analysis to determine how to use fuel property and chemistry information for engine control. We were able to show that selected outputs from the sensor correlated to both fuel properties and to engine performance. This collaboration leveraged our past statistical analysis work and further work will be done as opportunity permits. We conducted blending experiments to determine characteristics of ethanol blends based on the gasoline characteristics used for blending. Results indicate that much of the octane benefits gained by high level ethanol blending can be negated by use of low octane gasoline blend stocks, as allowed by ASTM D5798. This may limit ability to optimize engines for improved efficiency with ethanol fuels

  6. Energy recycling by co-combustion of coal and recovered paint solids from automobile paint operations.

    Science.gov (United States)

    Suriyawong, Achariya; Magee, Rogan; Peebles, Ken; Biswas, Pratim

    2009-05-01

    During the past decade, there has been substantial interest in recovering energy from many unwanted byproducts from industries and municipalities. Co-combustion of these products with coal seems to be the most cost-effective approach. The combustion process typically results in emissions of pollutants, especially fine particles and trace elements. This paper presents the results of an experimental study of particulate emission and the fate of 13 trace elements (arsenic [As], barium [Ba], cadmium [Cd], chromium [Cr], copper [Cu], cobalt [Co], manganese [Mn], molybdenum [Mo], nickel [Ni], lead [Pb], mercury [Hg], vanadium [V], and zinc [Zn]) during combustion tests of recovered paint solids (RPS) and coal. The emissions from combustions of coal or RPS alone were compared with those of co-combustion of RPS with subbituminous coal. The distribution/partitioning of these toxic elements between a coarse-mode ash (particle diameter [dp] > 0.5 microm), a submicrometer-mode ash (dp burning particles and the higher volatile chlorine species. Hg was completely volatilized in all cases; however, the fraction in the oxidized state increased with co-combustion. Most trace elements, except Zn, were retained in ash during combustion of RPS alone. Mo was mostly retained in all samples. The behavior of elements, except Mn and Mo, varied depending on the fuel samples. As, Ba, Cr, Co, Cu, and Pb were vaporized to a greater extent from cocombustion of RPS and coal than from combustion of either fuel. Evidence of the enrichment of certain toxic elements in submicrometer particles has also been observed for As, Cd, Cr, Cu, and Ni during co-combustion.

  7. Twenty-second symposium (international) on combustion

    Energy Technology Data Exchange (ETDEWEB)

    1989-01-01

    The following research areas were discussed at the symposium: coal combustion: carbon burnout, pyrolysis, furnaces, laboratory-scale combustion, and fluidized bed combustion; combustion-generated particulates: soot inception, growth, and soot formation in diffusion flames; engine combustion; turbulent combustion: flames in vortices, fractals and cellular automations, nonpremixed flames, premixed flames, premixed flame structure, and lifted flames; reaction kinetics: hydrocarbon oxidation, free radical chemistry, unsaturated species, aromatics, and nitrogen compounds/pollutant formation; combustion generated NO/sub x/ and SO/sub x/; fires: flame spread, radiation, characterization, and unsteady flames; Laminar flames: structure, opposed-flow combustion, shape, propagation/extinction, and inhibition, oscillations, microgravity; ignition; detonations; dusts; propellants; diagnostics; combustion of drops, sprays, and dispersions, and slurries. Individual projects are processed separately for the data bases. (CBS)

  8. Air/Fuel Ratio Control of Gasoline HCCI Engine Based on Neural Network%基于神经网络的汽油HCCI发动机空燃比控制策略

    Institute of Scientific and Technical Information of China (English)

    周能辉; 谢辉; 赵华; 陈韬

    2009-01-01

    均质压缩燃烧(HCCI)在控制上存在难点,其中关键是基于循环的空燃比实时控制.HCCI汽油机没有能直接表征发动机每循环进气量的参数,因此,采用动态递归神经网络(Elman网络)预测HCCI发动机每循环的进气量.通过氧传感器闭环和瞬态工况中的油膜补偿,实现对HCCI发动机的稳态及瞬态工况下空燃比的精确控制.试验表明:汽油HCCI发动机神经网络预测模型及空燃比控制策略能满足HCCI发动机实时控制的需求.

  9. Combustion iron distribution and deposition

    Science.gov (United States)

    Luo, Chao; Mahowald, N.; Bond, T.; Chuang, P. Y.; Artaxo, P.; Siefert, R.; Chen, Y.; Schauer, J.

    2008-03-01

    Iron is hypothesized to be an important micronutrient for ocean biota, thus modulating carbon dioxide uptake by the ocean biological pump. Studies have assumed that atmospheric deposition of iron to the open ocean is predominantly from mineral aerosols. For the first time we model the source, transport, and deposition of iron from combustion sources. Iron is produced in small quantities during fossil fuel burning, incinerator use, and biomass burning. The sources of combustion iron are concentrated in the industrialized regions and biomass burning regions, largely in the tropics. Model results suggest that combustion iron can represent up to 50% of the total iron deposited, but over open ocean regions it is usually less than 5% of the total iron, with the highest values (ocean biogeochemistry the bioavailability of the iron is important, and this is often estimated by the fraction which is soluble (Fe(II)). Previous studies have argued that atmospheric processing of the relatively insoluble Fe(III) occurs to make it more soluble (Fe(II)). Modeled estimates of soluble iron amounts based solely on atmospheric processing as simulated here cannot match the variability in daily averaged in situ concentration measurements in Korea, which is located close to both combustion and dust sources. The best match to the observations is that there are substantial direct emissions of soluble iron from combustion processes. If we assume observed soluble Fe/black carbon ratios in Korea are representative of the whole globe, we obtain the result that deposition of soluble iron from combustion contributes 20-100% of the soluble iron deposition over many ocean regions. This implies that more work should be done refining the emissions and deposition of combustion sources of soluble iron globally.

  10. Combustion Byproducts Recycling Consortium

    Energy Technology Data Exchange (ETDEWEB)

    Paul Ziemkiewicz; Tamara Vandivort; Debra Pflughoeft-Hassett; Y. Paul Chugh; James Hower

    2008-08-31

    The Combustion Byproducts Recycling Consortium (CBRC) program was developed as a focused program to remove and/or minimize the barriers for effective management of over 123 million tons of coal combustion byproducts (CCBs) annually generated in the USA. At the time of launching the CBRC in 1998, about 25% of CCBs were beneficially utilized while the remaining was disposed in on-site or off-site landfills. During the ten (10) year tenure of CBRC (1998-2008), after a critical review, 52 projects were funded nationwide. By region, the East, Midwest, and West had 21, 18, and 13 projects funded, respectively. Almost all projects were cooperative projects involving industry, government, and academia. The CBRC projects, to a large extent, successfully addressed the problems of large-scale utilization of CCBs. A few projects, such as the two Eastern Region projects that addressed the use of fly ash in foundry applications, might be thought of as a somewhat smaller application in comparison to construction and agricultural uses, but as a novel niche use, they set the stage to draw interest that fly ash substitution for Portland cement might not attract. With consideration of the large increase in flue gas desulfurization (FGD) gypsum in response to EPA regulations, agricultural uses of FGD gypsum hold promise for large-scale uses of a product currently directed to the (currently stagnant) home construction market. Outstanding achievements of the program are: (1) The CBRC successfully enhanced professional expertise in the area of CCBs throughout the nation. The enhanced capacity continues to provide technology and information transfer expertise to industry and regulatory agencies. (2) Several technologies were developed that can be used immediately. These include: (a) Use of CCBs for road base and sub-base applications; (b) full-depth, in situ stabilization of gravel roads or highway/pavement construction recycled materials; and (c) fired bricks containing up to 30%-40% F

  11. Natural Gas for Advanced Dual-Fuel Combustion Strategies

    Science.gov (United States)

    Walker, Nicholas Ryan

    Natural gas fuels represent the next evolution of low-carbon energy feedstocks powering human activity worldwide. The internal combustion engine, the energy conversion device widely used by society for more than one century, is capable of utilizing advanced combustion strategies in pursuit of ultra-high efficiency and ultra-low emissions. Yet many emerging advanced combustion strategies depend upon traditional petroleum-based fuels for their operation. In this research the use of natural gas, namely methane, is applied to both conventional and advanced dual-fuel combustion strategies. In the first part of this work both computational and experimental studies are undertaken to examine the viability of utilizing methane as the premixed low reactivity fuel in reactivity controlled compression ignition, a leading advanced dual-fuel combustion strategy. As a result, methane is shown to be capable of significantly extending the load limits for dual-fuel reactivity controlled compression ignition in both light- and heavy-duty engines. In the second part of this work heavy-duty single-cylinder engine experiments are performed to research the performance of both conventional dual-fuel (diesel pilot ignition) and advanced dual-fuel (reactivity controlled compression ignition) combustion strategies using methane as the premixed low reactivity fuel. Both strategies are strongly influenced by equivalence ratio; diesel pilot ignition offers best performance at higher equivalence ratios and higher premixed methane ratios, whereas reactivity controlled compression ignition offers superior performance at lower equivalence ratios and lower premixed methane ratios. In the third part of this work experiments are performed in order to determine the dominant mode of heat release for both dual-fuel combustion strategies. By studying the dual-fuel homogeneous charge compression ignition and single-fuel spark ignition, strategies representative of autoignition and flame propagation

  12. Computational modeling of high pressure combustion mechanism in scram accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Choi, J.Y. [Pusan Nat. Univ. (Korea); Lee, B.J. [Pusan Nat. Univ. (Korea); Agency for Defense Development, Taejon (Korea); Jeung, I.S. [Pusan Nat. Univ. (Korea); Seoul National Univ. (Korea). Dept. of Aerospace Engineering

    2000-11-01

    A computational study was carried out to analyze a high-pressure combustion in scram accelerator. Fluid dynamic modeling was based on RANS equations for reactive flows, which were solved in a fully coupled manner using a fully implicit-upwind TVD scheme. For the accurate simulation of high-pressure combustion in ram accelerator, 9-species, 25-step fully detailed reaction mechanism was incorporated with the existing CFD code previously used for the ram accelerator studies. The mechanism is based on GRI-Mech. 2.11 that includes pressure-dependent reaction rate formulations indispensable for the correct prediction of induction time in high-pressure environment. A real gas equation of state was also included to account for molecular interactions and real gas effects of high-pressure gases. The present combustion modeling is compared with previous 8-step and 19-step mechanisms with ideal gas assumption. The result shows that mixture ignition characteristics are very sensitive to the combustion mechanisms, and different mechanism results in different reactive flow-field characteristics that have a significant relevance to the operation mode and the performance of scram accelerator. (orig.)

  13. Three dimensional dynamic mode decomposition of premixed turbulent jet flames

    Science.gov (United States)

    Grenga, Temistocle; Macart, Jonathan; Mueller, Michael

    2016-11-01

    Analysis of turbulent combustion DNS data largely focuses on statistical analyses. However, turbulent combustion is highly unsteady and dynamic. In this work, Dynamic Mode Decomposition (DMD) will be explored as a tool for dynamic analysis of turbulent combustion DNS data, specifically a series of low Mach number spatially-evolving turbulent planar premixed hydrogen/air jet flames. DMD decomposes data into coherent modes with corresponding growth rates and oscillatory frequencies. The method identifies structures unbiased by energy so is particularly well suited to exploring dynamic processes at scales smaller than the largest, energy-containing scales of the flow and that may not be co-located in space and time. The focus of this work will be on both the physical insights that can potentially be derived from DMD modes and the computational issues associated with applying DMD to large three-dimensional DNS datasets.

  14. Subgrid Combustion Modeling for the Next Generation National Combustion Code

    Science.gov (United States)

    Menon, Suresh; Sankaran, Vaidyanathan; Stone, Christopher

    2003-01-01

    In the first year of this research, a subgrid turbulent mixing and combustion methodology developed earlier at Georgia Tech has been provided to researchers at NASA/GRC for incorporation into the next generation National Combustion Code (called NCCLES hereafter). A key feature of this approach is that scalar mixing and combustion processes are simulated within the LES grid using a stochastic 1D model. The subgrid simulation approach recovers locally molecular diffusion and reaction kinetics exactly without requiring closure and thus, provides an attractive feature to simulate complex, highly turbulent reacting flows of interest. Data acquisition algorithms and statistical analysis strategies and routines to analyze NCCLES results have also been provided to NASA/GRC. The overall goal of this research is to systematically develop and implement LES capability into the current NCC. For this purpose, issues regarding initialization and running LES are also addressed in the collaborative effort. In parallel to this technology transfer effort (that is continuously on going), research has also been underway at Georgia Tech to enhance the LES capability to tackle more complex flows. In particular, subgrid scalar mixing and combustion method has been evaluated in three distinctly different flow field in order to demonstrate its generality: (a) Flame-Turbulence Interactions using premixed combustion, (b) Spatially evolving supersonic mixing layers, and (c) Temporal single and two-phase mixing layers. The configurations chosen are such that they can be implemented in NCCLES and used to evaluate the ability of the new code. Future development and validation will be in spray combustion in gas turbine engine and supersonic scalar mixing.

  15. Turbulent Combustion in SDF Explosions

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, A L; Bell, J B; Beckner, V E

    2009-11-12

    A heterogeneous continuum model is proposed to describe the dispersion and combustion of an aluminum particle cloud in an explosion. It combines the gas-dynamic conservation laws for the gas phase with a continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models. It incorporates a combustion model based on the mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes into account both the afterburning of the detonation products of the C-4 booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Numerical simulations of the explosion fields from 1.5-g Shock-Dispersed-Fuel (SDF) charge in a 6.6 liter calorimeter were used to validate the combustion model. Then the model was applied to 10-kg Al-SDF explosions in a an unconfined height-of-burst explosion. Computed pressure histories are compared with measured waveforms. Differences are caused by physical-chemical kinetic effects of particle combustion which induce ignition delays in the initial reactive blast wave and quenching of reactions at late times. Current simulations give initial insights into such modeling issues.

  16. Explosion limits for combustible gases

    Institute of Scientific and Technical Information of China (English)

    TONG Min-ming; WU Guo-qing; HAO Ji-fei; DAI Xin-lian

    2009-01-01

    Combustible gases in coal mines are composed of methane, hydrogen, some multi-carbon alkane gases and other gases. Based on a numerical calculation, the explosion limits of combustible gases were studied, showing that these limits are related to the concentrations of different components in the mixture. With an increase of C4H10 and C6H14, the Lower ExplosionLimit (LEL) and Upper Explosion-Limit (UEL) of a combustible gas mixture will decrease clearly. For every 0.1% increase in C4H10 and C6H14, the LEL decreases by about 0.19% and the UEL by about 0.3%. The results also prove that, by increasing the amount of H2, the UEL of a combustible gas mixture will increase considerably. If the level of H2 increases by 0.1%, the UEL will increase by about 0.3%. However, H2 has only a small effect on the LEL of the combustible gas mixture. Our study provides a theoretical foundation for judging the explosion risk of an explosive gas mixture in mines.

  17. New Combustion Regimes and Kinetic Studies of Plasma Assisted Combustion

    Science.gov (United States)

    2012-11-01

    Tasks 8 and 9: Kinetic model validation) Today’s Presentation 2. Multispecies diagnostics in a flow reactor with Mid-IR and molecular beam mass...S-Curve Competition between low T RO2 kinetics high T chain branching reactions 0.00 0.02 0.04 0.06 0.08 0.10 0.12 1x10 5 2x10 5 3x10 5 4x10...in Plasma assisted combustion • LTC in turbulent combustion at engine time scales 0-D modeling of DME /O2/He (0.03/0.1/0.896) ignition, P = 72

  18. Dual-Fuel Combustion for Future Clean and Efficient Compression Ignition Engines

    Directory of Open Access Journals (Sweden)

    Jesús Benajes

    2016-12-01

    Full Text Available Stringent emissions limits introduced for internal combustion engines impose a major challenge for the research community. The technological solution adopted by the manufactures of diesel engines to meet the NOx and particle matter values imposed in the EURO VI regulation relies on using selective catalytic reduction and particulate filter systems, which increases the complexity and cost of the engine. Alternatively, several new combustion modes aimed at avoiding the formation of these two pollutants by promoting low temperature combustion reactions, are the focus of study nowadays. Among these new concepts, the dual-fuel combustion mode known as reactivity controlled compression ignition (RCCI seems more promising because it allows better control of the combustion process by means of modulating the fuel reactivity depending on the engine operating conditions. The present experimental work explores the potential of different strategies for reducing the energy losses with RCCI in a single-cylinder research engine, with the final goal of providing the guidelines to define an efficient dual-fuel combustion system. The results demonstrate that the engine settings combination, piston geometry modification, and fuel properties variation are good methods to increase the RCCI efficiency while maintaining ultra-low NOx and soot emissions for a wide range of operating conditions.

  19. Control strategies for CAI combustion processes; Strategien zur Regelung von CAI-Brennverfahren

    Energy Technology Data Exchange (ETDEWEB)

    Karrelmeyer, R.; Graf, G.; Scherrer, D.; Fischer, W.; Hathout, J.P. [Robert Bosch GmbH, Stuttgart (Germany)

    2008-07-01

    The contribution presents concepts for control of a CAI combustion process with internal exhaust trapping. The concepts are based on combustion characteristics obtained from the combustion chamber pressure signal. Combustion is controlled using the control variables of the air and fuel systems. The engines investigated were engines with variable valve drive, with different degrees of variability, and with a direct injection system. In a first step, a fully variable valve control system is investigated which enables adjustment of the gas change valves for the individual cylinders. In the second step, the cost aspect is considered and a control strategy is presented which does not control individual cylinders but uses a valve control strategy with conventional phase control elements. The control concepts presented here are a combination of pre-control and combustion characteristics control. Results obtained during operating mode switching, dynamic operation and stabilisation of the CAI mode are presented as well. Pre-control is particularly important in order to prevent misfires as well as extremely early and loud combustion both in dynamic operation and during switching. (orig.)

  20. Novel Active Combustion Control Valve

    Science.gov (United States)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  1. Combustion synthesis method and products

    Science.gov (United States)

    Holt, J.B.; Kelly, M.

    1993-03-30

    Disclosed is a method of producing dense refractory products, comprising: (a) obtaining a quantity of exoergic material in powder form capable of sustaining a combustion synthesis reaction; (b) removing absorbed water vapor therefrom; (c) cold-pressing said material into a formed body; (d) plasma spraying said formed body with a molten exoergic material to form a coat thereon; and (e) igniting said exoergic coated formed body under an inert gas atmosphere and pressure to produce self-sustained combustion synthesis. Also disclosed are products produced by the method.

  2. Chemical kinetics and combustion modeling

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The goal of this program is to gain qualitative insight into how pollutants are formed in combustion systems and to develop quantitative mathematical models to predict their formation rates. The approach is an integrated one, combining low-pressure flame experiments, chemical kinetics modeling, theory, and kinetics experiments to gain as clear a picture as possible of the process in question. These efforts are focused on problems involved with the nitrogen chemistry of combustion systems and on the formation of soot and PAH in flames.

  3. Fundamentals of premixed turbulent combustion

    CERN Document Server

    Lipatnikov, Andrei

    2012-01-01

    Lean burning of premixed gases is considered to be a promising combustion technology for future clean and highly efficient gas turbine engines. This book highlights the phenomenology of premixed turbulent flames. The text provides experimental data on the general appearance of premixed turbulent flames, physical mechanisms that could affect flame behavior, and physical and numerical models aimed at predicting the key features of premixed turbulent combustion. The author aims to provide a simple introduction to the field for advanced graduate and postgraduate students. Topics covered include La

  4. Autodesk Combustion 4 fundamentals courseware

    CERN Document Server

    Autodesk,

    2005-01-01

    Whether this is your first experience with Combustion software or you're upgrading to take advantage of the many new features and tools, this guide will serve as your ultimate resource to this all-in-one professional compositing application. Much more than a point-and-click manual, this guide explains the principles behind the software, serving as an overview of the package and associated techniques. Written by certified Autodesk training specialists for motion graphic designers, animators, and visual effects artists, Combustion 4 Fundamentals Courseware provides expert advice for all skill le

  5. A Pulverized Coal-Fired Boiler Optimized for Oxyfuel Combustion Technology

    Directory of Open Access Journals (Sweden)

    Tomáš Dlouhý

    2012-01-01

    Full Text Available This paper presents the results of a study on modifying a pulverized coal-fired steam boiler in a 250 MWe power plant for oxygen combustion conditions. The entry point of the study is a boiler that was designed for standard air combustion. It has been proven that simply substituting air by oxygen as an oxidizer is not sufficient for maintaining a satisfactory operating mode, not even with flue gas recycling. Boiler design optimization aggregating modifications to the boiler’s dimensions, heating surfaces and recycled flue gas flow rate, and specification of a flue gas recycling extraction point is therefore necessary in order to achieve suitable conditions for oxygen combustion. Attention is given to reducing boiler leakage, to which external pre-combustion coal drying makes a major contribution. The optimization is carried out with regard to an overall power plant conception for which a decrease in efficiency due to CO2 separation is formulated.

  6. An insight into chemical kinetics and turbulence-chemistry interaction modeling in flameless combustion

    Directory of Open Access Journals (Sweden)

    Amir Azimi, Javad Aminian

    2015-01-01

    Full Text Available Computational Fluid Dynamics (CFD study of flameless combustion condition is carried out by solving the Reynolds-Averaged Navier-Stokes (RANS equations in the open-source CFD package of OpenFOAM 2.1.0. Particular attention is devoted to the comparison of three global and detailed chemical mechanisms using the Partially Stirred Reactor (PaSR combustion model for the turbulence-chemistry interaction treatment. The OpenFOAM simulations are assessed against previously published CFD results using the Eddy Dissipation Concept (EDC combustion model as well as the experimental data available in the literature. Results show that global chemical mechanisms provide acceptable predictions of temperature and major species fields in flameless mode with much lower computational costs comparing with the detailed chemical mechanisms. However, incorporation of detailed chemical mechanisms with proper combustion models is crucial to account for finite-rate chemistry effects and accurately predict net production of minor species.

  7. Free Energy and Internal Combustion Engine Cycles

    CERN Document Server

    Harris, William D

    2012-01-01

    The performance of one type (Carnot) of Internal Combustion Engine (ICE) cycle is analyzed within the framework of thermodynamic free energies. ICE performance is different from that of an External Combustion Engine (ECE) which is dictated by Carnot's rule.

  8. Scramjet Combustion Stability Behavior Modeling Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A recent breakthrough in combustion stability analysis (UCDS) offers the means to accurately predict the combustion stability of a scramjet. This capability is very...

  9. Scramjet Combustion Stability Behavior Modeling Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A recent breakthrough in combustion stability analysis (UCDS) offers the potential to predict the combustion stability of a scramjet. This capability is very...

  10. Failure Modes

    DEFF Research Database (Denmark)

    Jakobsen, K. P.; Burcharth, H. F.; Ibsen, Lars Bo;

    1999-01-01

    The present appendix contains the derivation of ten different limit state equations divided on three different failure modes. Five of the limit state equations can be used independently of the characteristics of the subsoil, whereas the remaining five can be used for either drained or undrained...

  11. High Frequency Combustion Instabilities of LOx/CH4 Spray Flames in Rocket Engine Combustion Chambers

    NARCIS (Netherlands)

    Sliphorst, M.

    2011-01-01

    Ever since the early stages of space transportation in the 1940’s, and the related liquid propellant rocket engine development, combustion instability has been a major issue. High frequency combustion instability (HFCI) is the interaction between combustion and the acoustic field in the combustion c

  12. High Frequency Combustion Instabilities of LOx/CH4 Spray Flames in Rocket Engine Combustion Chambers

    NARCIS (Netherlands)

    Sliphorst, M.

    2011-01-01

    Ever since the early stages of space transportation in the 1940’s, and the related liquid propellant rocket engine development, combustion instability has been a major issue. High frequency combustion instability (HFCI) is the interaction between combustion and the acoustic field in the combustion c

  13. Study on Fitting Heat Release Rate of HCCI Combustion with Partition Lognormal Distribution Function%运用分段对数正态函数拟合HCCI燃烧放热规律的研究

    Institute of Scientific and Technical Information of China (English)

    张宗法; 熊锐; 罗伟欢; 周伟文

    2008-01-01

    在分析对数正态函数在HCCI燃烧放热率研究中的运用及其存在问题的基础上,首次提出了分段对数正态函数,并用其拟合了HCCI燃烧的实际放热率曲线.结果表明,分段对数正态函数可以充分反映HCCI燃烧的阶段性特征,拟合效果更好.

  14. Hybrid Combustion and Its Heat Release Rate Computing Model of an HCCI Gasoline Engine%HCCI汽油机混合燃烧及放热率计算模型

    Institute of Scientific and Technical Information of China (English)

    侯圣智; 谢辉; 陈韬; 胡顺堂; 赵华

    2009-01-01

    火花辅助点火HCCI燃烧,是介于纯均质压燃着火燃烧以及传统火花点火燃烧这2种燃烧模式之间的一种特殊的燃烧模式.为此,在全可变气门机构HCCI单缸试验发动机上.研究了火花辅助点火SI-HCCI燃烧模式过渡过程的燃烧特征.通过对火花辅助点火对HCCI燃烧及混合燃烧影响规律的系统分析,提出了产生混合燃烧必须满足的温度条件,建立了由SI向HCCI切换的判断条件计算函数;结合SI函数、HCCI函数和切换条件函数,构建了能够描述混合燃烧过程的燃烧放热率计算模型,为SI-HCCI模式过渡控制策略研究提供了理论依据和技术手段.

  15. Partition Webie Function Simulation Study on the Effect of EGR on HCCI Combustion%分段韦伯函数模拟EGR对HCCI燃烧影响的研究

    Institute of Scientific and Technical Information of China (English)

    周伟文; 熊锐; 张宗法

    2010-01-01

    EGR作为控制HCCI燃烧的手段之一,影响着燃烧始点和放热规律.本文考虑EGR因素建立HCCI燃烧的化学模型和计算模型,研究不同EGR率对HCCI燃烧始点的影响;并结合分段韦伯函数,对不同EGR率的HCCI放热率进行模拟研究.

  16. 分段韦伯函数拟合HCCI燃烧放热规律的研究%Study on Resembling the Heat Release Rate of HCCI Combustion with Partition Webie Function

    Institute of Scientific and Technical Information of China (English)

    罗伟欢; 熊锐

    2008-01-01

    研究HCCI燃烧放热规律有助于对HCCI燃烧的控制研究,韦伯函数是拟合燃烧放热率中应用最多的函数,但是由于HCCI燃烧的复杂性以及韦伯函数的局限性,拟合效果不是特别好.本文分析了韦伯函数在HCCI燃烧放热率研究中的运用及其存在的问题,首次提出了分段韦伯函数,并拟合了HCCI实际燃烧放热率曲线,结果表明,分段韦伯函数可以反映HCCI燃烧的阶段性,获得更好的拟合效果,适用性更佳.

  17. 内部EGR对HCCI燃烧及自由离子生成影响的数值研究%A Numerical Study on the Effects of Internal EGR on HCCI Combustion and Free Ion Formation

    Institute of Scientific and Technical Information of China (English)

    张志永; 董光宇; 邓俊; 李理光

    2009-01-01

    首先运用GT-Power和Chemkin软件建立HCCI发动机仿真试验平台,模拟了HCCI单缸试验样机的工作过程,计算出不同气门负重叠角时的内部EGR率.接着研究了不同的内部EGR率对自由离子生成和HCCI燃烧过程诸参数的影响,包括对最高燃烧温度、最大爆发压力、燃烧始点、燃烧持续期和CHO+与H3O+的摩尔分数的影响.最后探讨了仿真模型中引入Warnatz离子生成机理进行离子电流信号产生机理模拟研究的可行性.

  18. Simulation Study on Combustion Characteristic and Emissions of Natural Gas HCCI Engine%天然气HCCI发动机燃烧特性和排放物的数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    回胜; 孙锐

    2014-01-01

    本文分析利用CHEMKIN软件中的零维单区HCCI模型模拟了不同的边界参数包括:压缩比、进气温度、进气压力和转速对天然气HCCI发动机燃烧特性及排放物的影响.利用模拟的结果分析了边界参数的变化对发动机缸内温度、压力、着火时刻和污染物排放的影响,为合理选择天然气HCCI发动机的边界参数提供了参考.

  19. Experimental Research on High Load Extension of HCCI Combustion Using Gasoline and Methanol Stratification%用汽油和甲醇燃油分层拓展HCCI燃烧高负荷的试验研究

    Institute of Scientific and Technical Information of China (English)

    阳冬波; 王志; 王建昕

    2012-01-01

    在一台单缸HCCI发动机上研究了进气道喷射汽油缸内喷射甲醇形成汽油甲醇燃油分层的HCCI燃烧排放特性,探索了其拓展HCCI燃烧高负荷的潜力.试验结果表明:在汽油HCCI燃烧中喷射甲醇能够有效降低缸内混合气的温度,推迟着火时刻,延长燃烧持续期,从而降低压力升高率和缸内最高燃烧压力,有利于拓展HCCI燃烧高负荷.一定的HCCI负荷工况存在最佳的汽油甲醇比例,且汽油甲醇最佳比例随着负荷的增加不断减小.在最大压力升高率0.5 MPa/℃A和较高的指示效率的限制下,自然吸气条件下采用汽油和甲醇燃油分层的HCCI燃烧最高负荷比汽油HCCI燃烧提高了近50%,达到0.62 MPa.

  20. Large-eddy Simulation on Combustion Characteristics of Isooctane HCCI Engine%异辛烷HCCI发动机燃烧特性的大涡数值模拟

    Institute of Scientific and Technical Information of China (English)

    曾文; 宋崇林

    2009-01-01

    通过修改发动机多维CFD计算程序KIVA-3V,并与化学动力学程序CHEMKIN Ⅲ相耦合,建立了异辛烷HCCI发动机燃烧过程的大涡模拟(LES)计算模型.利用此模型对异辛烷HCCI发动机的燃烧特性进行了详细分析.发动机以异辛烷为燃料,其化学反应采用了详细的动力学机理.结果表明:大涡模拟所得到的缸内压力变化趋势与试验基本吻合;采用LES模型计算时,缸内混合气燃烧区域以柱形向四周扩散,而采用k-ε模型计算时以球形向四周扩散.

  1. 燃料辛烷值对HCCI燃烧特征和排放特性的影响%Combustion Parameters and Emissions of HCCI Using Primary Reference Fuels and Their Mixtures

    Institute of Scientific and Technical Information of China (English)

    吕兴才; 陈伟; 黄震

    2005-01-01

    将一台4缸高速轻型柴油机中的一缸改装,使其具有独立的进排气系统和燃油供给系统,研究了参比燃料及其混合物在均质压燃过程中的着火时刻、燃烧速率和NOx、UHC、CO排放.考察了正庚烷、异辛烷和各种不同比例的混合物在常温、常压下各种负荷的燃烧特性.研究发现:随燃料辛烷值增加,第一阶段着火时刻推迟,燃烧持续期缩短,第一阶段反应结束时的压力升高量和温度升高量减少;第一阶段的累积放热量取决于燃料中高十六烷值燃料的浓度;第二阶段的着火时刻与第一阶段着火时刻呈线性关系;第二阶段燃烧持续期随当量比的增加而减小,且随辛烷值增加而延长;随燃料十六烷值和当量比增加,CO和UHC排放大幅度改善.

  2. Mechanism of instabilities in turbulent combustion leading to flashback

    Science.gov (United States)

    Keller, J. O.; Vaneveld, L.; Ghoniem, A. F.; Daily, J. W.; Oppenheim, A. K.; Korschelt, D.; Hubbard, G. L.

    1981-01-01

    High-speed schlieren cinematography, combined with synchronized pressure transducer records, was used to investigate the mechanism of combustion instabilities leading to flashback. The combustion chamber had an oblong rectangular cross-section to model the essential features of planar flow, and was provided with a rearward facing step acting as a flameholder. As the rich limit was approached, three instability modes were observed: (1) humming - a significant increase in the amplitude of the vortex pattern; (2) buzzing - a large-scale oscillation of the flame; and (3) chucking - a cyclic reformation of the flame, which results in flashback. The mechanism of these phenomena is ascribed to the action of vortices in the recirculation zone and their interactions with the trailing vortex pattern of the turbulent mixing layer behind the step.

  3. Thermal analysis and combustion kinetic of heavy oils

    Energy Technology Data Exchange (ETDEWEB)

    Santos, R.G. [Centre for Petroleum Studies, State University of Campinas(Brazil); Vargas, J.A.V.; Trevisan, O.V. [Department of Petroleum Engineering, Faculty of Mechanical Engineering, State University of Campinas (Brazil)

    2011-07-01

    In the oilfield sector, a thermal method named in-situ combustion (ISC) is used as an enhanced recovery method. ISC consists of the injection of gas into the reservoir, a combustion front is created producing heat which reduces the oil viscosity. For this method to be successful, understanding of the thermal and kinetic parameters involved is required; the aim of this paper is to evaluate those parameters for different crude oils. Experiments were conducted using accelerating rate calorimetry on Brazilian heavy oil samples under a heat-wait-seek-mode. Results showed that accelerating rate calorimetry is efficient in resolving the three main regions of reaction of the oil and that between 200 degree C and 300 degree C oxygen addition reactions are dominant while bond scission reactions dominate from 350 degree C. This study demonstrated that accelerating rate calorimetry is an efficient method to determine thermal and kinetic parameters of oxidation reaction of heavy oil.

  4. Combustion Chemistry Diagnostics for Cleaner Processes.

    Science.gov (United States)

    Kohse-Höinghaus, Katharina

    2016-09-12

    Climate change, environmental problems, urban pollution, and the dependence on fossil fuels demand cleaner, renewable energy strategies. However, they also ask for urgent advances in combustion science to reduce emissions. For alternative fuels and new combustion regimes, crucial information about the chemical reactions from fuel to exhaust remains lacking. Understanding such relations between combustion process, fuel, and emissions needs reliable experimental data from a wide range of conditions to provide a firm basis for predictive modeling of practical combustion processes.

  5. Simulation study on combustion of biomass

    Science.gov (United States)

    Zhao, M. L.; Liu, X.; Cheng, J. W.; Liu, Y.; Jin, Y. A.

    2017-01-01

    Biomass combustion is the most common energy conversion technology, offering the advantages of low cost, low risk and high efficiency. In this paper, the transformation and transfer of biomass in the process of combustion are discussed in detail. The process of furnace combustion and gas phase formation was analyzed by numerical simulation. The experimental results not only help to optimize boiler operation and realize the efficient combustion of biomass, but also provide theoretical basis for the improvement of burner technology.

  6. Combustor nozzle for a fuel-flexible combustion system

    Science.gov (United States)

    Haynes, Joel Meier [Niskayuna, NY; Mosbacher, David Matthew [Cohoes, NY; Janssen, Jonathan Sebastian [Troy, NY; Iyer, Venkatraman Ananthakrishnan [Mason, OH

    2011-03-22

    A combustor nozzle is provided. The combustor nozzle includes a first fuel system configured to introduce a syngas fuel into a combustion chamber to enable lean premixed combustion within the combustion chamber and a second fuel system configured to introduce the syngas fuel, or a hydrocarbon fuel, or diluents, or combinations thereof into the combustion chamber to enable diffusion combustion within the combustion chamber.

  7. Changes in the composition of synthesis products upon transitioning from self-ignition to combustion

    Science.gov (United States)

    Seplyarskii, B. S.; Ivleva, T. P.; Grachev, V. V.; Merzhanov, A. G.

    2017-07-01

    Changes in the chemical composition of condensed products upon switching from synthesis in the self-ignition mode to combustion synthesis is studied by approximate analytical and numerical means for condensed substances that react via competing reaction pathways. It is shown that these different modes of synthesis produce different compositions of the reaction products. The conditions required for transitioning from one mode of combustion initiation (thermal explosion) to another (ignition) are determined. It is found that this transition can occur upon changing the temperature of a heater by just two characteristic intervals. A scaling procedure that allows the calculation results obtained at zero dimensionless temperature of the heater to be used to determine the effect its non-zero dimensionless temperature has on the ignition mode and the composition of the obtained products is proposed. Calculations show that materials with different distributions of the chemical composition along the sample can be obtained by deliberately changing the temperature of the heater.

  8. 30 CFR 56.4104 - Combustible waste.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Combustible waste. 56.4104 Section 56.4104... Control Prohibitions/precautions/housekeeping § 56.4104 Combustible waste. (a) Waste materials, including... properly, waste or rags containing flammable or combustible liquids that could create a fire hazard shall...

  9. Straw combustion on slow-moving grates

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    2005-01-01

    Combustion of straw in grate-based boilers is often associated with high emission levels and relatively poor fuel burnout. A numerical grate combustion model was developed to assist in improving the combustion performance of these boilers. The model is based on a one-dimensional ‘‘walking...

  10. DI Diesel Performance and Emissions Models

    Science.gov (United States)

    2007-11-02

    homogeneous charge compression ignition or HCCI . The use of HCCI as a distinct, controlled engine operating mode was suggested over twenty years...ago by Onishi et al. (1979) and Noguchi et al. (1979) for use in two-stroke gasoline engines . Initial studies using HCCI in four-stroke engines were...depending on the operating conditions. Engines operated in HCCI mode have the potential to provide better fuel economy and emissions than

  11. Development of colorless distributed combustion for gas turbine application

    Science.gov (United States)

    Arghode, Vaibhav Kumar

    cross-flow configuration was found to give more favorable results possibly due to higher residence time because of reverse flow geometry and faster mixing with the fuel injection in cross-flow. This configuration was investigated in detail by further reducing the combustor volume to give ultra-high thermal intensity of up to 198MW/m3-atm. At thermal intensity of 53MW/m3-atm NO emissions were 4ppm in non-premixed mode and 1ppm in premixed mode and CO emissions were 30ppm in both the modes. The pressure loss was less than 5% and heat loss was less than 15%. The pressure fluctuations were less than 0.025% suggesting very stable combustion. At ultra-high thermal intensity of 170MW/m3-atm NO emissions were 8ppm and 3ppm in non-premixed and premixed modes respectively and CO emissions were about 100ppm in both the modes. Dilution of fuel with nitrogen, carbon dioxide and air resulted in significant reduction in NO emission in non-premixed mode from 8ppm to about 2ppm. Methane was used as fuel for all these investigations. Liquid fuel (ethanol) was also tested and very low NO emission of about 6ppm was obtained in direct injection mode and 2ppm in premixed prevaporized mode. CO emission of about 200ppm was observed in both the modes.

  12. Experimental investigation of gasoline compression ignition combustion in a light-duty diesel engine

    Science.gov (United States)

    Loeper, C. Paul

    fuel consumption (gross indicated fuel consumption HCCI - Controlling Pressure- Rise Rates for Performance Improvements using Partial Fuel Stratification with Conventional Gasoline," SAE Int. J. Engines, 4(1), pp. 1169-1189. [2] Kalghatgi, G., Hildingsson, L., and Johansson, B., 2010, "Low NO(x) and Low Smoke Operation of a Diesel Engine Using Gasolinelike Fuels," Journal of Engineering for Gas Turbines and Power-Transactions of the Asme, 132(9), p. 9. [3] Manente, V., Zander, C.-G., Johansson, B., Tunestal, P., and Cannella, W., 2010, "An Advanced Internal Combustion Engine Concept for Low Emissions and High Efficiency from Idle to Max Load Using Gasoline Partially Premixed Combustion," SAE International, 2010-01-2198. [4] Ra, Y., Loeper, P., Reitz, R., Andrie, M., Krieger, R., Foster, D., Durrett, R., Gopalakrishnan, V., Plazas, A., Peterson, R., and Szymkowicz, P., 2011, "Study of High Speed Gasoline Direct Injection Compression Ignition (GDICI) Engine Operation in the LTC Regime," SAE Int. J. Engines, 4(1), pp. 1412-1430. [5] Ra, Y., Loeper, P., Andrie, M., Krieger, R., Foster, D., Reitz, R., and Durrett, R., 2012, "Gasoline DICI Engine Operation in the LTC Regime Using Triple- Pulse Injection," SAE Int. J. Engines, 5(3), pp. 1109-1132.

  13. Health impacts of domestic coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Finkelman, R.B.

    1999-07-01

    poisoning. Better knowledge of coal quality parameters may help to reduce some of these health problems. For example, information on concentrations and distributions of potentially toxic elements in coal may help delineate areas of a coal deposit to be avoided. Information on the modes of occurrence of these elements and the textural relations of the minerals and macerals in coal may help predict the behavior of the potentially toxic components during coal combustion.

  14. Sulfur Chemistry in Combustion II

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Kiil, Søren

    2000-01-01

    Several options are available to control the emission of SO2 from combustion processes. One possibility is to use a cleaner technology, i.e. fuel switching from oil and coal to natural gas or biomass, or to desulphurize coal and oil. Another possibility is to change to a different technology for ...

  15. Leaching from biomass combustion ash

    DEFF Research Database (Denmark)

    Maresca, Alberto; Astrup, Thomas Fruergaard

    2014-01-01

    The use of biomass combustion ashes for fertilizing and liming purposes has been widely addressed in scientific literature. Nevertheless, the content of potentially toxic compounds raises concerns for a possible contamination of the soil. During this study five ash samples generated at four...

  16. Method for operating a spark-ignition, direct-injection internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Narayanaswamy, Kushal; Koch, Calvin K.; Najt, Paul M.; Szekely, Jr., Gerald A.; Toner, Joel G.

    2015-06-02

    A spark-ignition, direct-injection internal combustion engine is coupled to an exhaust aftertreatment system including a three-way catalytic converter upstream of an NH3-SCR catalyst. A method for operating the engine includes operating the engine in a fuel cutoff mode and coincidentally executing a second fuel injection control scheme upon detecting an engine load that permits operation in the fuel cutoff mode.

  17. Environmental optimisation of waste combustion

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Robert [AaF Energikonsult, Stockholm (Sweden); Berge, Niclas; Stroemberg, Birgitta [TPS Termiska Processer AB, Nykoeping (Sweden)

    2000-12-01

    The regulations concerning waste combustion evolve through R and D and a strive to get better and common regulations for the European countries. This study discusses if these rules of today concerning oxygen concentration, minimum temperature and residence time in the furnace and the use of stand-by burners are needed, are possible to monitor, are the optimum from an environmental point of view or could be improved. No evidence from well controlled laboratory experiments validate that 850 deg C in 6 % oxygen content in general is the best lower limit. A lower excess air level increase the temperature, which has a significant effect on the destruction of hydrocarbons, favourably increases the residence time, increases the thermal efficiency and the efficiency of the precipitators. Low oxygen content is also necessary to achieve low NO{sub x}-emissions. The conclusion is that the demands on the accuracy of the measurement devices and methods are too high, if they are to be used inside the furnace to control the combustion process. The big problem is however to find representative locations to measure temperature, oxygen content and residence time in the furnace. Another major problem is that the monitoring of the operation conditions today do not secure a good combustion. It can lead to a false security. The reason is that it is very hard to find boilers without stratifications. These stratifications (stream lines) has each a different history of residence time, mixing time, oxygen and combustible gas levels and temperature, when they reach the convection area. The combustion result is the sum of all these different histories. The hydrocarbons emission is in general not produced at a steady level. Small clouds of unburnt hydrocarbons travels along the stream lines showing up as peaks on a THC measurement device. High amplitude peaks has a tendency to contain higher ratio of heavy hydrocarbons than lower peaks. The good correlation between some easily detected

  18. Fluidized-bed combustion of gasification residue

    Energy Technology Data Exchange (ETDEWEB)

    Kudjoi, A.; Heinolainen, A.; Hippinen, I.; Lu, Y. [Helsinki University of Technology, Espoo (Finland). Lab. of Energy Economics and Power Plant Engineering

    1998-12-31

    Hybrid combined cycle processes have been presented as possibilities for power generation in the future. In the processes based on partial gasification of coal, the solid materials removed from a gasifier (i.e. fly ash and bed char) contain unburned fuel, which is burned either in an atmospheric or a pressurised fluidised-bed. Pressurised fluidised-bed (PFB) combustion of gasification residues were studied experimentally by Helsinki University of Technology. The gasification residues, i.e. cyclone fines and bed chars, came from pilot scale PFB gasification tests of bituminous coals. The combustion efficiency was high in cyclone fines combustion. The calcium sulphide oxidised effectively to calcium sulphate in the combustion of cyclone fines. In bed char combustion the residual sulphide contents in solids after combustion were still relatively high. In general, sulphur dioxide emissions in residue combustion were low. The recarbonation of calcium oxide was observed in bed char combustion. Fuel-N conversion to NO{sub x} during bed char combustion and in most of the test runs with cyclone fines was higher than in bituminous coal combustion. In bed char combustion the conversion was significantly higher than in cyclone fines combustion. NO{sub x} emissions increased with increasing excess air for both residues, as was expected. In bed char combustion the highest NO{sub x} emissions were measured at higher pressure. Calculated mass reactivity values of equal particle size of all bed chars studied had similar trends with burnout. The biggest particles had the lowest reactivity values throughout the combustion, while reactivity for finer particles was at considerably higher level and sharply increases with burnout. In the constant combustion conditions used in the tests, no significant differences were observed in rate-controlling mechanisms for bed char fractions studied. 25 refs., 13 figs., 15 tab.

  19. Combustive management of oil spills

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    Extensive experiments with in situ incineration were performed on a desert site at the University of Arizona with very striking results. The largest incinerator, 6 feet in diameter with a 30 foot chimney, developed combustion temperatures of 3000, F, and attendant soot production approximately 1000 times less than that produced by conventional in situ burning. This soot production, in fact, is approximately 30 times less than current allowable EPA standards for incinerators and internal combustion engines. Furthermore, as a consequence of the high temperature combustion, the bum rate was established at a very high 3400 gallons per hour for this particular 6 foot diameter structure. The rudimentary design studies we have carried out relative to a seagoing 8 foot diameter incinerator have predicted that a continuous burn rate of 7000 gallons per hour is realistic. This structure was taken as a basis for operational design because it is compatible with C130 flyability, and will be inexpensive enough ($120,000 per copy) to be stored at those seaside depots throughout the US coast line in which the requisite ancillary equipments (booms, service tugs, etc.) are already deployed. The LOX experiments verified our expectations with respect to combustion of debris and various highly weathered or emulsified oils. We have concluded, however, that the use of liquid oxygen in actual beach clean up is not promising because the very high temperatures associated with this combustion are almost certain to produce environmentally deleterious effects on the beach surface and its immediately sublying structures. However, the use of liquid oxygen augmentation for shore based and flyable incinerators may still play an important role in handing the problem of accumulated debris.

  20. Comparison of Diesel Spray Combustion in Different High-temperature, High-pressure Facilities

    DEFF Research Database (Denmark)

    Pickett, Lyle M.; Genzale, Caroline L.; Bruneaux, Gilles

    2010-01-01

    Diesel spray experimentation at controlled high-temperature and high-pressure conditions is intended to provide a more fundamental understanding of diesel combustion than can be achieved in engine experiments. This level of understanding is needed to develop the high-fidelity multi-scale CFD mode...

  1. Secondary combustion device for woodburning stove

    Energy Technology Data Exchange (ETDEWEB)

    Craver, R.D.

    1989-08-08

    This patent describes in a wood burning stove including an exhaust flue opening, a combustion chamber for primary combustion having an access door, a support for wood to be burned and a primary air inlet means for supplying air to support primary combustion of the wood to produce flue gases containing combustible particulate material, plenum means for directing the flue gases in a direction from the combustion chamber to the flue opening in a preselected path, and secondary combustion means for burning the particulate material in the flue gases before flue gases through the exhaust flue opening. The improvement comprising: the combustion chamber having a flue gas exit opening extending laterally across the top of the combustion chamber and communicating the combustion chamber with the plenum means, an elongated manifold extending laterally across and above the combustion chamber substantially coextensively with the flue gas exit opening, a number of air opening spaced longitudinally along the manifold and facing opposite the direction of the flue gases closely adjacent the flue gas exit opening, and an air inlet means for supplying ambient, secondary combustion air to the manifold for counterflow thereof from the openings into the path of the flue gases in a plurality of distinct jets.

  2. Measurement and simulation of swirling coal combustion

    Institute of Scientific and Technical Information of China (English)

    Liyuan Hu; Lixing Zhou; Yonghao Luo; Caisong Xu

    2013-01-01

    Particle image velocimetry (PIV),thermocouples and flue gas analyzer are used to study swirling coal combustion and NO formation under different secondary-air ratios.Eulerian-Lagrangian large-eddy simulation (LES) using the Smagorinsky-Lilly sub-grid scale stress model,presumed-PDF fast chemistry and eddy-break-up (EBU) gas combustion models,particle devolatilization and particle combustion models,are simultaneously used to simulate swirling coal combustion.Statistical LES results are validated by measurement results.Instantaneous LES results show that the coherent structures for swirling coal combustion are stronger than those for swirling gas combustion.Particles are shown to concentrate along the periphery of the coherent structures.Combustion flame is located in the high vorticity and high particle concentration zones.Measurement shows that secondary-air ratios have little effect on final NO formation at the exit of the combustor.

  3. 77 FR 37361 - National Emission Standards for Hazardous Air Pollutants for Reciprocating Internal Combustion...

    Science.gov (United States)

    2012-06-21

    ... Reciprocating Internal Combustion Engines; New Source Performance Standards for Stationary Internal Combustion... Combustion Engines; New Source Performance Standards for Stationary Internal Combustion Engines.'' The EPA... Internal Combustion Engines; New Source Performance Standards for Stationary Internal Combustion Engines...

  4. Experimental investigation on combustion of hydrogen-oxygen and methane-oxygen mixtures in the medium of low-superheated steam

    Science.gov (United States)

    Pribaturin, N. A.; Fedorov, V. A.; Alekseev, M. V.; Bogomolov, A. R.; Sorokin, A. L.; Azikhanov, S. S.; Shevyrev, S. A.

    2016-05-01

    Experimental data are represented on the investigation of combustion of hydrogen-oxygen and methane-oxygen mixtures in the medium of low-superheated (initial temperature of approximately 150°C) steam at atmospheric pressure. The influence of the ratio of mass flows of the combustible mixture and steam on the qualitative composition of combustion products and the temperature of produced steam is revealed. Main laws for combustion of the hydrogen-oxygen mixture within the steam flow, which affect the completeness of mixture combustion, are determined. Experimental data on the influence of concentrations of the hydrogen-oxygen mixture within the flow of the steam and the combustible mixture upon the completeness of combustion are given. It is found that, when burning the hydrogen-oxygen mixture within the steam flow with a temperature of 1000-1200°C, it is possible using a variation of the combustible mixture flow. At the same time, the volume fraction of noncondensable gases in the produced steam is no more than 2%. It is revealed that there are several combustion modes of the hydrogen-oxygen mixture within the steam flow, in which, in one case, the steam always suppresses combustion and, in another one, detonation of the combustible mixture combustible mixture occurs. It is found that with the excess air factor close to unit, the combustion of the methane-oxygen mixture within steam and the vapor conversion of methane, which result in the appearance of free hydrogen in the produced high-temperature steam, are possible. The description and the principle of the operation of the experimental bench for investigation of combustion of methane-oxygen and hydrogen-oxygen mixtures in the medium of steam are given. Results of experimental investigations of burning fuel and oxygen in the medium of steam are used in the development of a steam superheater for a hightemperature steam turbine.

  5. Enhancement of Combustion and Flame Stabilization Using Transient Non-Equilibrium Plasma

    Science.gov (United States)

    2007-03-31

    compression ignition ( HCCI ) engines . When atn external energy is locally deposited into a comnbttStibfe mnixtture. there are four possible oultcomnes: tin...Aerospace Engineering 34th Street and Lancaster EQUAD on Olden Street Avenue Princeton, NJ 08544 Philadelphia, PA 19104 9. SPONSORING / MONITORING...Principle Investigator: Yiguang Ju Department of Mechanical and Aerospace Engineering Princeton University D330, Engineering Quadrangle, Olden Street

  6. An Investigation of Compressed Natural Gas Engine for Nitrogen Oxides Reduction

    Directory of Open Access Journals (Sweden)

    P. M. Diaz

    2012-01-01

    Full Text Available Problem statement: This study describes the use of Reformer Gas (RG to alter NOx emission in a CNG-fueled HCCI engine. Comparison with diesel, natural gas has a very high octane number (≈120 and high auto-ignition temperature (≈600°C. Composed mostly of methane, natural gas is the only common fuel to manifest relatively pure, single-stage combustion. Other fuels have stronger low-temperature reaction and the required entropy for main stage combustion can be obtained from the low temperature heat release as a result of compression to moderate pressure and temperature. In deviation, the methane molecule resists destruction by free radicals and produces negligible heat release at low temperature. In consequences, in CNG-fueled HCCI engines the activation energy required for auto-ignition must be obtained by extreme levels of charge heating and compression. This causes inherently to a high rate of heat release. HCCI operation with pure CNG fuel was attained but not really practical due to very high NOx production. While HCCI operation is usually described as a low NOx technique, the knocking behavior when running with pure CNG raised the peak combustion temperature to a value well above normal combustion and the critical Zeldovich NOx production threshold, giving very high indicated NOx emissions. Approach: One approach to improving these properties is to convert part of the base CNG fuel to Reformer Gas (RG. In this study, modified COMET engine was operated in HCCI mode using a mixture of CNG fuel and simulated RG (75% H2 and 25% CO can be produced on-board from CNG using low current and non-thermal plasma boosted fuel converter. Results: This study shows that despite of having various RG mass fractions, λ was the dominant factor in reducing NOx production and increasing RG mass fraction had only a small effect on increasing NOx. This disconnect between the overall equivalence ratio and RG fraction shows that the real benefit of the

  7. Performance of a flameless combustion furnace using biogas and natural gas.

    Science.gov (United States)

    Colorado, A F; Herrera, B A; Amell, A A

    2010-04-01

    Flameless combustion technology has proved to be flexible regarding the utilization of conventional fuels. This flexibility is associated with the main characteristic of the combustion regime, which is the mixing of the reactants above the autoignition temperature of the fuel. Flameless combustion advantages when using conventional fuels are a proven fact. However, it is necessary to assess thermal equipments performance when utilizing bio-fuels, which usually are obtained from biomass gasification and the excreta of animals in bio-digesters. The effect of using biogas on the performance of an experimental furnace equipped with a self-regenerative Flameless burner is reported in this paper. All the results were compared to the performance of the system fueled with natural gas. Results showed that temperature field and uniformity are similar for both fuels; although biogas temperatures were slightly lower due to the larger amount of inert gases (CO(2)) in its composition that cool down the reactions. Species patterns and pollutant emissions showed similar trends and values for both fuels, and the energy balance for biogas showed a minor reduction of the efficiency of the furnace; this confirms that Flameless combustion is highly flexible to burn conventional and diluted fuels. Important modifications on the burner were not necessary to run the system using biogas. Additionally, in order to highlight the advantages of the Flameless combustion regime, some comparisons of the burner performance working in Flameless mode and working in conventional mode are presented.

  8. Oxy-coal Combustion Studies

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, J. [Univ. of Utah, Salt Lake City, UT (United States); Eddings, E. [Univ. of Utah, Salt Lake City, UT (United States); Lighty, J. [Univ. of Utah, Salt Lake City, UT (United States); Ring, T. [Univ. of Utah, Salt Lake City, UT (United States); Smith, P. [Univ. of Utah, Salt Lake City, UT (United States); Thornock, J. [Univ. of Utah, Salt Lake City, UT (United States); Y Jia, W. Morris [Univ. of Utah, Salt Lake City, UT (United States); Pedel, J. [Univ. of Utah, Salt Lake City, UT (United States); Rezeai, D. [Univ. of Utah, Salt Lake City, UT (United States); Wang, L. [Univ. of Utah, Salt Lake City, UT (United States); Zhang, J. [Univ. of Utah, Salt Lake City, UT (United States); Kelly, K. [Univ. of Utah, Salt Lake City, UT (United States)

    2012-01-06

    The objective of this project is to move toward the development of a predictive capability with quantified uncertainty bounds for pilot-scale, single-burner, oxy-coal operation. This validation research brings together multi-scale experimental measurements and computer simulations. The combination of simulation development and validation experiments is designed to lead to predictive tools for the performance of existing air fired pulverized coal boilers that have been retrofitted to various oxy-firing configurations. In addition, this report also describes novel research results related to oxy-combustion in circulating fluidized beds. For pulverized coal combustion configurations, particular attention is focused on the effect of oxy-firing on ignition and coal-flame stability, and on the subsequent partitioning mechanisms of the ash aerosol.

  9. Steady state HNG combustion modeling

    Energy Technology Data Exchange (ETDEWEB)

    Louwers, J.; Gadiot, G.M.H.J.L. [TNO Prins Maurits Lab., Rijswijk (Netherlands); Brewster, M.Q. [Univ. of Illinois, Urbana, IL (United States); Son, S.F. [Los Alamos National Lab., NM (United States); Parr, T.; Hanson-Parr, D. [Naval Air Warfare Center, China Lake, CA (United States)

    1998-04-01

    Two simplified modeling approaches are used to model the combustion of Hydrazinium Nitroformate (HNF, N{sub 2}H{sub 5}-C(NO{sub 2}){sub 3}). The condensed phase is treated by high activation energy asymptotics. The gas phase is treated by two limit cases: the classical high activation energy, and the recently introduced low activation energy approach. This results in simplification of the gas phase energy equation, making an (approximate) analytical solution possible. The results of both models are compared with experimental results of HNF combustion. It is shown that the low activation energy approach yields better agreement with experimental observations (e.g. regression rate and temperature sensitivity), than the high activation energy approach.

  10. Fundamental studies of spray combustion

    Energy Technology Data Exchange (ETDEWEB)

    Li, S.C.; Libby, P.A.; Williams, F.A. [Univ. of California, San Diego, CA (United States)

    1997-12-31

    Our research on spray combustion involves both experiment and theory and addresses the characteristics of individual droplets and of sprays in a variety of flows: laminar and turbulent, opposed and impinging. Currently our focus concerns water and fuel sprays in two stage laminar flames, i.e., flames arising, for example from a stream of fuel and oxidizer flowing opposite to an air stream carrying a water spray. Our interest in these flames is motivated by the goals of reducing pollutant emissions and extending the range of stable spray combustion. There remains considerable research to be carried out in order to achieve these goals. Thus far our research on the characteristics of sprays in turbulent flows has been limited to nonreacting jets impinging on a plate but this work will be extended to opposed flows with and without a flame. In the following we discuss details of these studies and our plans for future work.

  11. SPECIFIC EMISSIONS FROM BIOMASS COMBUSTION

    Directory of Open Access Journals (Sweden)

    Pavel Skopec

    2014-02-01

    Full Text Available This paper deals with determining the specific emissions from the combustion of two kinds of biomass fuels in a small-scale boiler. The tested fuels were pellets made of wood and pellets made of rape plant straw. In order to evaluate the specific emissions, several combustion experiments were carried out using a commercial 25 kW pellet-fired boiler. The specific emissions of CO, SO2 and NOx were evaluated in relation to a unit of burned fuel, a unit of calorific value and a unit of produced heat. The specific emissions were compared with some data acquired from the reference literature, with relatively different results. The differences depend mainly on the procedure used for determining the values, and references provide no information about this. Although some of our experimental results may fit with one of the reference sources, they do not fit with the other. The reliability of the references is therefore disputable.

  12. Fluidized bed coal combustion reactor

    Science.gov (United States)

    Moynihan, P. I.; Young, D. L. (Inventor)

    1981-01-01

    A fluidized bed coal reactor includes a combination nozzle-injector ash-removal unit formed by a grid of closely spaced open channels, each containing a worm screw conveyor, which function as continuous ash removal troughs. A pressurized air-coal mixture is introduced below the unit and is injected through the elongated nozzles formed by the spaces between the channels. The ash build-up in the troughs protects the worm screw conveyors as does the cooling action of the injected mixture. The ash layer and the pressure from the injectors support a fluidized flame combustion zone above the grid which heats water in boiler tubes disposed within and/or above the combustion zone and/or within the walls of the reactor.

  13. The FCF Combustion Integrated Rack: Microgravity Combustion Science Onboard the International Space Station

    Science.gov (United States)

    OMalley, Terence F.; Weiland, Karen J.

    2002-01-01

    The Combustion Integrated Rack (CIR) is one of three facility payload racks being developed for the International Space Station (ISS) Fluids and Combustion Facility (FCF). Most microgravity combustion experiments will be performed onboard the Space Station in the Combustion Integrated Rack. Experiment-specific equipment will be installed on orbit in the CIR to customize it to perform many different scientific experiments during the ten or more years that it will operate on orbit. This paper provides an overview of the CIR, including a description of its preliminary design and planned accommodations for microgravity combustion science experiments, and descriptions of the combustion science experiments currently planned for the CIR.

  14. CSIR helps prevent spontaneous combustion

    Energy Technology Data Exchange (ETDEWEB)

    Vuuren, M. van (CSIR Energy Technology (South Africa))

    1992-03-01

    Heaps of stockpiled coal could present a fire hazard due to the risk of spontaneous combustion. Regular monitoring of stockpiles and bunker testing of coals help to prevent stockpile fires. This brief article describes the recent upgrading of the CSIR's bunker test facility that enables coal producers, users and exporters to test their products under simulated conditions that duplicate the actual conditions under which coal is stored. 2 photos.

  15. Radiation/Catalytic Augmented Combustion.

    Science.gov (United States)

    1980-09-01

    NATIO& NAk H(fJI At tl TANUAHTOb 19 A ~omm.81-0287 LVL RADIATION/CATALYTIC AUGMENTED COMBUST ION MOSHE LAVID CORPORATE RESEARCH-TECHNOLOGY FEASIBILITY...refinements as necessary. i. Perform cannular combustor experiments to Investigate ignition and flame attachment in flowing, liquid -fuel, unpremixed...stabilizer, with a sintered metal disk on the downstream side through which hot gases or products of partial fuel oxidation can be passed. Experimental

  16. Laser Optics/Combustion Diagnostics.

    Science.gov (United States)

    1986-07-01

    been demonstrated. CARS measurements of axial and 0.12 radial temperature profiles in a highly sooting flame compared favorably with profiles...of Number-Density Equation ’Eckbreth. A.C. and Hatt. R.., "CARS Thermomrry in a The third-order susceptibility can be rewritten to show its Sooting ... Flame ." Combustion and Homie, Vol. 36. 1979, pp. 87-98. explcitdepndece ponthenumer ensty Roh. %W.B.. "Coherent Anti-Stokcs Raman Scattering ofexpici

  17. ABB Combustion Engineering nuclear technology

    Energy Technology Data Exchange (ETDEWEB)

    Matzie, R.A.

    1994-12-31

    The activities of ABB Combustion Engineering in the design and construction of nuclear systems and components are briefly reviewed. ABB Construction Engineering continues to improve the design and design process for nuclear generating stations. Potential improvements are evaluated to meet new requirements both of the public and the regulator, so that the designs meet the highest standards worldwide. Advancements necessary to meet market needs and to ensure the highest level of performance in the future will be made.

  18. Vortex Simulation of Turbulent Combustion

    Science.gov (United States)

    1992-11-19

    TURBULENT COMBUSTION (AFOSR Grant No. 89-0491) Principal Investigator: Ahmed F. Ghoniem Department of Mechanical Engineering Massachusetts Institute of...Heavy Industries, Nagoya, Japan.(talk and discussion). 17. 1990, Mazda Motor Co., Yokohama, Japan, (talk and discussion). 18. 1990, American Math Society...VORTICITY LAYERS UNDER NON-SYMMETRIC CONDITIONS Omar M. Kniot and Ahmed F. Ghoniem Department of Mechanical Engineering Massachusetts Institute of

  19. Nitrogen release during coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, L.L.; Mitchell, R.E.; Fletcher, T.H.; Hurt, R.H.

    1995-02-01

    Experiments in entrained flow reactors at combustion temperatures are performed to resolve the rank dependence of nitrogen release on an elemental basis for a suite of 15 U.S. coals ranging from lignite to low-volatile bituminous. Data were obtained as a function of particle conversion, with overall mass loss up to 99% on a dry, ash-free basis. Nitrogen release rates are presented relative to both carbon loss and overall mass loss. During devolatilization, fractional nitrogen release from low-rank coals is much slower than fractional mass release and noticeably slower than fractional carbon release. As coal rank increases, fractional nitrogen release rate relative to that of carbon and mass increases, with fractional nitrogen release rates exceeding fractional mass and fractional carbon release rates during devolatilization for high-rank (low-volatile bituminous) coals. At the onset of combustion, nitrogen release rates increase significantly. For all coals investigated, cumulative fractional nitrogen loss rates relative to those of mass and carbon passes through a maximum during the earliest stages of oxidation. The mechanism for generating this maximum is postulated to involve nascent thermal rupture of nitrogen-containing compounds and possible preferential oxidation of nitrogen sites. During later stages of oxidation, the cumulative fractional loss of nitrogen approaches that of carbon for all coals. Changes in the relative release rates of nitrogen compared to those of both overall mass and carbon during all stages of combustion are attributed to a combination of the chemical structure of coals, temperature histories during combustion, and char chemistry.

  20. Fundamental Insights into Combustion Instability Predictions in Aerospace Propulsion

    Science.gov (United States)

    Huang, Cheng

    Integrated multi-fidelity modeling has been performed for combustion instability in aerospace propulsion, which includes two levels of analysis: first, computational fluid dynamics (CFD) using hybrid RANS/LES simulations for underlying physics investigations (high-fidelity modeling); second, modal decomposition techniques for diagnostics (analysis & validation); third, development of flame response model using model reduction techniques for practical design applications (low-order model). For the high-fidelity modeling, the relevant CFD code development work is moving towards combustion instability prediction for liquid propulsion system. A laboratory-scale single-element lean direct injection (LDI) gas turbine combustor is used for configuration that produces self-excited combustion instability. The model gas turbine combustor is featured with an air inlet section, air plenum, swirler-venturi-injector assembly, combustion chamber, and exit nozzle. The combustor uses liquid fuel (Jet-A/FT-SPK) and heated air up to 800K. Combustion dynamics investigations are performed with the same geometry and operating conditions concurrently between the experiment and computation at both high (φ=0.6) and low (φ=0.36) equivalence ratios. The simulation is able to reach reasonable agreement with experiment measurements in terms of the pressure signal. Computational analyses are also performed using an acoustically-open geometry to investigate the characteristic hydrodynamics in the combustor with both constant and perturbed inlet mass flow rates. Two hydrodynamic modes are identified by using Dynamic Mode Decomposition (DMD) analysis: Vortex Breakdown Bubble (VBB) and swirling modes. Following that, the closed geometry simulation results are analyzed in three steps. In step one, a detailed cycle analysis shows two physically important couplings in the combustor: first, the acoustic compression enhances the spray drop breakup and vaporization, and generates more gaseous fuel for

  1. Energetic study of combustion instabilities and genetic optimisation of chemical kinetics; Etude energetique des instabilites thermo-acoustiques et optimisation genetique des cinetiques reduites

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Ch.E.

    2005-12-15

    Gas turbine burners are now widely operated in lean premixed combustion mode. This technology has been introduced in order to limit pollutants emissions (especially the NO{sub x}), and thus comply with environment norms. Nevertheless, the use of lean premixed combustion decreases the stability margin of the flames. The flames are then more prone to be disturbed by flow disturbances. Combustion instabilities are then a major problem of concern for modern gas turbine conception. Some active control systems have been used to ensure stability of gas turbines retro-fitted to lean premixed combustion. The current generation of gas turbines aims to get rid of these control devices getting stability by a proper design. To do so, precise and adapted numerical tools are needed even it is impossible at the moment to guarantee the absolute stability of a combustion chamber at the design stage. Simulation tools for unsteady combustion are now able to compute the whole combustion chamber. Its intrinsic precision, allows the Large Eddy Simulation (LES) to take into account numerous phenomena involved in combustion instabilities. Chemical modelling is an important element for the precision of reactive LES. This study includes the description of an optimisation tools for the reduced chemical kinetics. The capacity of the LES to capture combustion instabilities in gas turbine chamber is also demonstrated. The acoustic energy analysis points out that the boundary impedances of the combustion systems are of prime importance for their stability. (author)

  2. Combustion char characterisation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, P.; Ingermann Petersen, H.; Sund Soerensen, H.; Thomsen, E.; Guvad, C.

    1996-06-01

    The aim was to correlate reactivity measures of raw coals and the maceral concentrates of the coals obtained in a previous project with the morphology of the produced chars by using a wire grid devolatilization method. Work involved determination of morphology, macroporosity and a detailed study by Scanning Electron Microscopy (SEM). Systematic variations in the texture of chars produced in different temperature domains and heating rates were demonstrated by using incident light microscopy on polished blocks and by SEM studies directly on the surfaces of untreated particles. Results suggest that work in the field of char reactivity estimates and correlations between char morphology and coal petrography can be accomplished only on chars produced under heating rates and temperatures comparable to those for the intended use of coal. A general correlation between the coals` petrography and the the morphology of high temperature chars was found. The SEM study of the chars revealed that during the devolatilization period the particles fuse and the macroporosity and thus the morphotypes are formed. After devolatilization ceases, secondary micropores are formed. These develop in number and size throughout the medium combustion interval. At the end of the combustion interval the macrostructure breaks down, caused by coalescence of the increased number of microspores. This can be observed as a change in the morphology and the macroporosity of the chars. Results indicate that char reactivity is a function of the macroporosity and thus the morphology of combustion chars. (AB) 34 refs.

  3. Demonstration of Active Combustion Control

    Science.gov (United States)

    Lovett, Jeffrey A.; Teerlinck, Karen A.; Cohen, Jeffrey M.

    2008-01-01

    The primary objective of this effort was to demonstrate active control of combustion instabilities in a direct-injection gas turbine combustor that accurately simulates engine operating conditions and reproduces an engine-type instability. This report documents the second phase of a two-phase effort. The first phase involved the analysis of an instability observed in a developmental aeroengine and the design of a single-nozzle test rig to replicate that phenomenon. This was successfully completed in 2001 and is documented in the Phase I report. This second phase was directed toward demonstration of active control strategies to mitigate this instability and thereby demonstrate the viability of active control for aircraft engine combustors. This involved development of high-speed actuator technology, testing and analysis of how the actuation system was integrated with the combustion system, control algorithm development, and demonstration testing in the single-nozzle test rig. A 30 percent reduction in the amplitude of the high-frequency (570 Hz) instability was achieved using actuation systems and control algorithms developed within this effort. Even larger reductions were shown with a low-frequency (270 Hz) instability. This represents a unique achievement in the development and practical demonstration of active combustion control systems for gas turbine applications.

  4. Combustion instability modeling and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Santoro, R.J.; Yang, V.; Santavicca, D.A. [Pennsylvania State Univ., University Park, PA (United States)] [and others

    1995-10-01

    It is well known that the two key elements for achieving low emissions and high performance in a gas turbine combustor are to simultaneously establish (1) a lean combustion zone for maintaining low NO{sub x} emissions and (2) rapid mixing for good ignition and flame stability. However, these requirements, when coupled with the short combustor lengths used to limit the residence time for NO formation typical of advanced gas turbine combustors, can lead to problems regarding unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions, as well as the occurrence of combustion instabilities. Clearly, the key to successful gas turbine development is based on understanding the effects of geometry and operating conditions on combustion instability, emissions (including UHC, CO and NO{sub x}) and performance. The concurrent development of suitable analytical and numerical models that are validated with experimental studies is important for achieving this objective. A major benefit of the present research will be to provide for the first time an experimentally verified model of emissions and performance of gas turbine combustors.

  5. Modeling the internal combustion engine

    Science.gov (United States)

    Zeleznik, F. J.; Mcbride, B. J.

    1985-01-01

    A flexible and computationally economical model of the internal combustion engine was developed for use on large digital computer systems. It is based on a system of ordinary differential equations for cylinder-averaged properties. The computer program is capable of multicycle calculations, with some parameters varying from cycle to cycle, and has restart capabilities. It can accommodate a broad spectrum of reactants, permits changes in physical properties, and offers a wide selection of alternative modeling functions without any reprogramming. It readily adapts to the amount of information available in a particular case because the model is in fact a hierarchy of five models. The models range from a simple model requiring only thermodynamic properties to a complex model demanding full combustion kinetics, transport properties, and poppet valve flow characteristics. Among its many features the model includes heat transfer, valve timing, supercharging, motoring, finite burning rates, cycle-to-cycle variations in air-fuel ratio, humid air, residual and recirculated exhaust gas, and full combustion kinetics.

  6. Decoupled sedimentary records of combustion: Causes and implications

    Science.gov (United States)

    Hanke, Ulrich M.; Eglinton, Timothy I.; Braun, Ana L. L.; Reddy, Christopher M.; Wiedemeier, Daniel B.; Schmidt, Michael W. I.

    2016-05-01

    Pyrogenic carbon (PyC) is a collective term for carbon-rich residues comprised of a continuum of products arising from biomass burning and fossil-fuel combustion. PyC is ubiquitous in the environment where it can be transported by wind and water before being deposited in aquatic sediments. We compare results from four different methods used to trace PyC that were applied to a high-temporal resolution sedimentary record in order to constrain changes in PyC concentrations and fluxes over the past ~250 years. We find markedly discordant records for different PyC tracers, particularly during the preindustrial age, implying different origins and modes of supply of sedimentary PyC. In addition to providing new insights into the composition of sedimentary combustion products, this study reveals that elucidation of past combustion processes and development of accurate budgets of PyC production and deposition on local to regional scales requires careful consideration of both source characteristics and transport processes.

  7. Large Eddy Simulation of High-Speed, Premixed Ethylene Combustion

    Science.gov (United States)

    Ramesh, Kiran; Edwards, Jack R.; Chelliah, Harsha; Goyne, Christopher; McDaniel, James; Rockwell, Robert; Kirik, Justin; Cutler, Andrew; Danehy, Paul

    2015-01-01

    A large-eddy simulation / Reynolds-averaged Navier-Stokes (LES/RANS) methodology is used to simulate premixed ethylene-air combustion in a model scramjet designed for dual mode operation and equipped with a cavity for flameholding. A 22-species reduced mechanism for ethylene-air combustion is employed, and the calculations are performed on a mesh containing 93 million cells. Fuel plumes injected at the isolator entrance are processed by the isolator shock train, yielding a premixed fuel-air mixture at an equivalence ratio of 0.42 at the cavity entrance plane. A premixed flame is anchored within the cavity and propagates toward the opposite wall. Near complete combustion of ethylene is obtained. The combustor is highly dynamic, exhibiting a large-scale oscillation in global heat release and mass flow rate with a period of about 2.8 ms. Maximum heat release occurs when the flame front reaches its most downstream extent, as the flame surface area is larger. Minimum heat release is associated with flame propagation toward the cavity and occurs through a reduction in core flow velocity that is correlated with an upstream movement of the shock train. Reasonable agreement between simulation results and available wall pressure, particle image velocimetry, and OH-PLIF data is obtained, but it is not yet clear whether the system-level oscillations seen in the calculations are actually present in the experiment.

  8. Hardware Assisted ROP Detection Mode (HARD Mode)

    Science.gov (United States)

    2013-08-01

    Distribution A. Cleared for public release; unlimited distribution. USAFA-CN-2013-457 Hardware Assisted ROP Detection Mode (HARD Mode) NATHANIEL HART...457 This report, "Hardware Assisted ROP Detection Mode (HARD Mode)" is presented as a competent treatment of the subj ect, worthy of publication. The...Technical 20120810-20121215 Hardware Assisted ROP Detection Mode (HARD Mode) NATHANIEL HART MICHAEL WINSTEAD MARTIN CARLISLE RODNEY LYKINS MICHAEL

  9. Effects of Mode Shares on Mode Choice

    OpenAIRE

    Carlos Carrion; Nebiyou Tilahun; David Levinson

    2011-01-01

    This study considers the influence of the knowledge of existing mode shares on travelers mode choice. This contrasts with traditional mode choice models, where the main objective is to predict the overall mode shares as the aggregate of individual mode choices according to variables encompassing attributes of the modes, and characteristics of the travelers. In this study, a computer-administered adaptive stated preference survey is developed and applied to a sample of subjects selected from t...

  10. COMBUSTION SIMULATION IN A SPARK IGNITION ENGINE CYLINDER: EFFECTS OF AIR-FUEL RATIO ON THE COMBUSTION DURATION

    OpenAIRE

    2010-01-01

    Combustion is an important subject of internal combustion engine studies. To reduce the air pollution from internal combustion engines and to increase the engine performance, it is required to increase combustion efficiency. In this study, effects of air/fuel ratio were investigated numerically. An axisymmetrical internal combustion engine was modeled in order to simulate in-cylinder engine flow and combustion. Two dimensional transient continuity, momentum, turbulence, energy, and combustion...

  11. Low Temperature Combustion with Thermo-Chemical Recuperation to Maximize In-Use Engine Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Nigel N. Clark; Francisco Posada; Clinton Bedick; John Pratapas; Aleksandr Kozlov; Martin Linck; Dmitri Boulanov

    2009-03-30

    experimental results suggest that the LTC-TCR combination may offer a high efficiency solution to engine operation. A single zone model using a detailed chemical kinetic mechanism was implemented in CHEMKIN and to study the effects of base fuel and steam-fuel reforming products on the ignition timing and heat release characteristics. The study was performed considering the reformed fuel species composition for total n-heptane conversion (ideal case) and also at the composition corresponding to a specific set of operational reforming temperatures (real case). The computational model confirmed that the reformed products have a strong influence on the low temperature heat release (LTHR) region, affecting the onset of the high temperature heat release (HTHR). The ignition timing was proportionally delayed with respect to the baseline fuel case when higher concentrations of reformed gas were used. For stoichiometric concentration of RG, it was found that by increasing the proportion of reformed fuel to total fuel (RG), from 0% to 30%, the amount of energy released during the LTHR regime, or HR{sub L}, was reduced by 48% and the ignition timing was delayed 10.4 CA degrees with respect to the baseline fuel case. For RG composition corresponding to certain operational reforming temperatures, it was found that the most significant effects on the HCCI combustion, regarding HR{sub L} reduction and CA50 delay, was obtained by RG produced at a reforming temperature range of 675 K-725 K.

  12. Combustion dynamics of low vapour pressure nanofuel droplets

    Science.gov (United States)

    Pandey, Khushboo; Chattopadhyay, Kamanio; Basu, Saptarshi

    2017-07-01

    Multiscale combustion dynamics, shape oscillations, secondary atomization, and precipitate formation have been elucidated for low vapour pressure nanofuel [n-dodecane seeded with alumina nanoparticles (NPs)] droplets. Dilute nanoparticle loading rates (0.1%-1%) have been considered. Contrary to our previous studies of ethanol-water blend (high vapour pressure fuel), pure dodecane droplets do not exhibit internal boiling after ignition. However, variation in surface tension due to temperature causes shape deformations for pure dodecane droplets. In the case of nanofuels, intense heat release from the enveloping flame leads to the formation of micron-size aggregates (of alumina NPS) which serve as nucleation sites promoting heterogeneous boiling. Three boiling regimes (A, B, and C) have been identified with varying bubble dynamics. We have deciphered key mechanisms responsible for the growth, transport, and rupture of the bubbles. Bubble rupture causes ejections of liquid droplets termed as secondary atomization. Ejection of small bubbles (mode 1) resembles the classical vapour bubble collapse mechanism near a flat free surface. However, large bubbles induce severe shape deformations as well as bulk oscillations. Rupture of large bubbles results in high speed liquid jet formation which undergoes Rayleigh-Plateau tip break-up. Both modes contribute towards direct fuel transfer from the droplet surface to flame envelope bypassing diffusion limitations. Combustion lifetime of nanofuel droplets consequently has two stages: stage I (where bubble dynamics are dominant) and stage II (formation of gelatinous mass due to continuous fuel depletion; NP agglomeration). In the present work, variation of flame dynamics and spatio-temporal heat release (HR) have been analysed using high speed OH* chemiluminescence imaging. Fluctuations in droplet shape and flame heat release are found to be well correlated. Droplet flame is bifurcated in two zones (I and II). Flame response is

  13. Low temperature combustion of organic coal-water fuel droplets containing petrochemicals while soaring in a combustion chamber model

    Directory of Open Access Journals (Sweden)

    Valiullin Timur R.

    2017-01-01

    Full Text Available The paper examines the integral characteristics (minimum temperature, ignition delay times of stable combustion initiation of organic coal-water fuel droplets (initial radius is 0.3-1.5 mm in the oxidizer flow (the temperature and velocity varied in ranges 500-900 K, 0.5-3 m/s. The main components of organic coal-water fuel were: brown coal particles, filter-cakes obtained in coal processing, waste engine, and turbine oils. The different modes of soaring and ignition of organic coal-water fuel have been established. The conditions have been set under which it is possible to implement the sustainable soaring and ignition of organic coal-water fuel droplets. We have compared the ignition characteristics with those defined in the traditional approach (based on placing the droplets on a low-inertia thermocouple junction into the combustion chamber. The paper shows the scale of the influence of heat sink over the thermocouple junction on ignition inertia. An original technique for releasing organic coal-water fuel droplets to the combustion chamber was proposed and tested. The limitations of this technique and the prospects of experimental results for the optimization of energy equipment operation were also formulated.

  14. TOXIC SUBSTANCES FROM COAL COMBUSTION

    Energy Technology Data Exchange (ETDEWEB)

    A KOLKER; AF SAROFIM; CL SENIOR; FE HUGGINS; GP HUFFMAN; I OLMEZ; J LIGHTY; JOL WENDT; JOSEPH J HELBLE; MR AMES; N YAP; R FINKELMAN; T PANAGIOTOU; W SEAMES

    1998-12-08

    The Clean Air Act Amendments of 1990 identify a number of hazardous air pollutants (HAPs) as candidates for regulation. Should regulations be imposed on HAP emissions from coal-fired power plants, a sound understanding of the fundamental principles controlling the formation and partitioning of toxic species during coal combustion will be needed. With support from the Federal Energy Technology Center (FETC), the Electric Power Research Institute, the Lignite Research Council, and VTT (Finland), Physical Sciences Inc. (PSI) has teamed with researchers from USGS, MIT, the University of Arizona (UA), the University of Kentucky (UK), the University of Connecticut (UC), the University of Utah (UU) and the University of North Dakota Energy and Environmental Research Center (EERC) to develop a broadly applicable emissions model useful to regulators and utility planners. The new Toxics Partitioning Engineering Model (ToPEM) will be applicable to all combustion conditions including new fuels and coal blends, low-NO combustion systems, and new power generation x plants. Development of ToPEM will be based on PSI's existing Engineering Model for Ash Formation (EMAF). This report covers the reporting period from 1 July 1998 through 30 September 1998. During this period distribution of all three Phase II coals was completed. Standard analyses for the whole coal samples were also completed. Mössbauer analysis of all project coals and fractions received to date has been completed in order to obtain details of the iron mineralogy. The analyses of arsenic XAFS data for two of the project coals and for some high arsenic coals have been completed. Duplicate splits of the Ohio 5,6,7 and North Dakota lignite samples were taken through all four steps of the selective leaching procedure. Leaching analysis of the Wyodak coal has recently commenced. Preparation of polished coal/epoxy pellets for probe/SEM studies is underway. Some exploratory mercury LIII XAFS work was

  15. Sandia Combustion Research Program: Annual report, 1986

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    This report presents research results of the past year, divided thematically into some ten categories. Publications and presentations arising from this work are included in the appendix. Our highlighted accomplishment of the year is the announcement of the discovery and demonstration of the RAPRENOx process. This new mechanism for the elimination of nitrogen oxides from essentially all kinds of combustion exhausts shows promise for commercialization, and may eventually make a significant contribution to our nation's ability to control smog and acid rain. The sections of this volume describe the facility's laser and computer system, laser diagnostics of flames, combustion chemistry, reacting flows, liquid and solid propellant combustion, mathematical models of combustion, high-temperature material interfaces, studies of engine/furnace combustion, coal combustion, and the means of encouraging technology transfer. 182 refs., 170 figs., 12 tabs.

  16. TWO-DIMENSIONAL AXISYMMETRIC MODELING OF COMBUSTION IN AN IRON ORE SINTERING BED

    DEFF Research Database (Denmark)

    Lafmejani, Saeed Sadeghi; Davazdah Emami, Mohsen; Panjehpour, Masoud;

    2013-01-01

    A twodimensional model, based on conservation of mass, momentum and energy equations, is represented in this paper in which the coke combustion process, for iron ore sintering in a packed bed, is simulated numerically. The aforementioned packed bed consists of iron ore, coke, limestone and moisture...... of species are solved numerically by using a computational fluid dynamics code in a discrete solving domain. Modeling of iron ore sintering has complex and various features like coke combustion, complicated physical changes of solid phase particles and different modes of heat transfer, for example convection...

  17. An experimental investigation of the combustion performance of human faeces.

    Science.gov (United States)

    Onabanjo, Tosin; Kolios, Athanasios J; Patchigolla, Kumar; Wagland, Stuart T; Fidalgo, Beatriz; Jurado, Nelia; Hanak, Dawid P; Manovic, Vasilije; Parker, Alison; McAdam, Ewan; Williams, Leon; Tyrrel, Sean; Cartmell, Elise

    2016-11-15

    Poor sanitation is one of the major hindrances to the global sustainable development goals. The Reinvent the Toilet Challenge of the Bill and Melinda Gates Foundation is set to develop affordable, next-generation sanitary systems that can ensure safe treatment and wide accessibility without compromise on sustainable use of natural resources and the environment. Energy recovery from human excreta is likely to be a cornerstone of future sustainable sanitary systems. Faeces combustion was investigated using a bench-scale downdraft combustor test rig, alongside with wood biomass and simulant faeces. Parameters such as air flow rate, fuel pellet size, bed height, and fuel ignition mode were varied to establish the combustion operating range of the test rig and the optimum conditions for converting the faecal biomass to energy. The experimental results show that the dry human faeces had a higher energy content (∼25 MJ/kg) than wood biomass. At equivalence ratio between 0.86 and 1.12, the combustion temperature and fuel burn rate ranged from 431 to 558 °C and 1.53 to 2.30 g/min respectively. Preliminary results for the simulant faeces show that a minimum combustion bed temperature of 600 ± 10 °C can handle faeces up to 60 wt.% moisture at optimum air-to-fuel ratio. Further investigation is required to establish the appropriate trade-off limits for drying and energy recovery, considering different stool types, moisture content and drying characteristics. This is important for the design and further development of a self-sustained energy conversion and recovery systems for the NMT and similar sanitary solutions.

  18. Experimental research on combustion fluorine retention using calcium-based sorbets during coal combustion (Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    QI Qing-jie; LIN Zhi-yan; LIU Jian-zhong; WU Xian; ZHOU Jun-hu; CEN Ke-fa

    2008-01-01

    In order to provide experimental guide to commercial use of fluorine pollution control during coal combustion, with fluorine pollution control during coal combustion in mind, this paper proposed the theory of combustion fluorine retention technology. Feasibility of fluorine retention reaction with calcium-based fluorine retention agent was analyzed through thermo-dynamic calculation during coal combustion. By simulating the restraining and retention effects and influential factors of calcium-based sorbets on vaporized fluoride during experimental combustion using fixed bed tube furnace, the paper systematically explored the influential law of such factors as combustion temperature, retention time, and added quantities of calcium-based sorbets on effects of fluorine retention. The research result shows that adding calcium-based fluorine retention agent in coal combustion has double effects of fluorine retention and sulfur retention, it lays an experimental foundation for commercial test of combustion fluorine retention.

  19. Fuel combustion test in constant volume combustion chamber with built-in adaptor

    Institute of Scientific and Technical Information of China (English)

    JEONG; DongSoo; CHO; GyuBack; CHOI; SuJin; LEE; JinSoo

    2010-01-01

    Combustion tests of pre-mixture of methane and air in constant volume combustion chamber(CVCC) have been carried out by means of flame propagation photo and gas pressure measurement,the effects of CVCC body temperature,intake pressure of pre-mixture of methane and air,equivalence ratio and location of the built-in adaptor have been investigated.The whole combustion chamber can be divided into two parts,i.e.the upper combustion chamber and the lower combustion chamber,by the built-in adaptor with through hole.Owing to the built-in adaptor with through hole,jet ignition or compression ignition(auto-ignition) phenomena may occur in the lower combustion chamber,which is helpful to getting higher flame propagation velocity,higher combustion peak pressure,low cycle-to-cycle variation and more stable combustion process.

  20. Numerical and Experimental Investigation of Combustion and Knock in a Dual Fuel Gas/Diesel Compression Ignition Engine

    OpenAIRE

    Gharehghani, A.; S. M. Mirsalim; S. A. Jazayeri

    2012-01-01

    Conventional compression ignition engines can easily be converted to a dual fuel mode of operation using natural gas as main fuel and diesel oil injection as pilot to initiate the combustion. At the same time, it is possible to increase the output power by increasing the diesel oil percentage. A detailed performance and combustion characteristic analysis of a heavy duty diesel engine has been studied in dual fuel mode of operation where natural gas is used as the main fuel and diesel oil as p...