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Sample records for charge compression ignition

  1. AN INTRODUCTION TO A HOMOGENEOUS CHARGE COMPRESSION IGNITION ENGINE

    Directory of Open Access Journals (Sweden)

    A.A. Hairuddin

    2014-12-01

    Full Text Available Homogeneous charge compression ignition (HCCI engine technology is relatively new and has not matured sufficiently to be commercialised compared with conventional engines. It can use spark ignition or compression ignition engine configurations, capitalizing on the advantages of both: high engine efficiency with low emissions levels. HCCI engines can use a wide range of fuels with low emissions levels. Due to these advantages, HCCI engines are suitable for use in a hybrid engine configuration, where they can reduce the fuel consumption even further. However, HCCI engines have some disadvantages, such as knocking and a low to medium operating load range, which need to be resolved before the engine can be commercialised. Therefore, a comprehensive study has to be performed to understand the behaviour of HCCI engines.

  2. Exhaust gas recirculation in a homogeneous charge compression ignition engine

    Science.gov (United States)

    Duffy, Kevin P.; Kieser, Andrew J.; Rodman, Anthony; Liechty, Michael P.; Hergart, Carl-Anders; Hardy, William L.

    2008-05-27

    A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.

  3. Homogeneous Charge Compression Ignition Free Piston Linear Alternator

    Energy Technology Data Exchange (ETDEWEB)

    Janson Wu; Nicholas Paradiso; Peter Van Blarigan; Scott Goldsborough

    1998-11-01

    An experimental and theoretical investigation of a homogeneous charge compression ignition (HCCI) free piston powered linear alternator has been conducted to determine if improvements can be made in the thermal and conversion efficiencies of modern electrical generator systems. Performance of a free piston engine was investigated using a rapid compression expansion machine and a full cycle thermodynamic model. Linear alternator performance was investigated with a computer model. In addition linear alternator testing and permanent magnet characterization hardware were developed. The development of the two-stroke cycle scavenging process has begun.

  4. Modeling of homogeneous charge compression ignition (HCCI) of methane

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J.R.; Aceves, S.M.; Westbrook, C.; Pitz, W.

    1997-05-01

    The operation of piston engines on a compression ignition cycle using a lean, homogeneous charge has many potential attractive features. These include the potential for extremely low NO{sub x} and particulate emissions while maintaining high thermal efficiency and not requiring the expensive high pressure injection system of the typical modem diesel engine. Using the HCT chemical kinetics code to simulate autoignition of methane-air mixtures, we have explored the ignition timing, burn duration, NO{sub x} production, indicated efficiency and power output of an engine with a compression ratio of 15:1 at 1200 and 2400 rpm. HCT was modified to include the effects of heat transfer. This study used a single control volume reaction zone that varies as a function of crank angle. The ignition process is controlled by varying the intake equivalence ratio and varying the residual gas trapping (RGT). RGT is internal exhaust gas recirculation which recycles both heat and combustion product species. It is accomplished by varying the timing of the exhaust valve closure. Inlet manifold temperature was held constant at 330 Kelvins. Results show that there is a narrow range of operational conditions that show promise of achieving the control necessary to vary power output while keeping indicated efficiency above 50% and NO{sub x} levels below 100 ppm.

  5. 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.

  6. 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.

  7. Homogeneous Charge Compression Ignition Combustion of Dimethyl Ether

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr

    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...... mechanism for DME developed at Lawrence Livermore National Laboratory in 2004 [2]. The dominating reactions paths were then identified and used to create a simple reaction mechanism containing 55 reactions only. It contains just enough reactions to successfully predict ignition as well as low and high...... 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    2011-01-31

    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

  9. Experimental and Skeletal Kinetic Model Study of Compressed Natural Gas Fueled Homogeneous Charge Compression Ignition Engine

    Directory of Open Access Journals (Sweden)

    P. M. Diaz

    2012-01-01

    Full Text Available Problem statement: In homogeneous charge compression ignition engines fuel oxidation chemistry determines the auto-ignition timing, heat release, reaction intermediates and the ultimate products of combustion. To shorten development time and to understand combustion processes, the use of simulation is increasing. Approach: A model that correctly simulates fuel oxidation at these conditions would be a useful design tool. Detailed models of hydrocarbon fuel oxidation, consisting of hundreds of chemical species and thousands of reactions. A way to lessen the burden was to use a skeletal reaction model, containing only tens of species and reactions. Results: The model was developed from the existing pre-ignition model, which had 10 species, 5 elementary reactions for kinetic and 6 elementary reactions for equilibrium and the standard k-ε turbulence model had been used in this investigation. This model combines the chemistry of the low, intermediate and high temperature regions. Conclusion: Simulations are compared with measured and calculated data from the engine operating at the following conditions: speed 1500 RPM, inlet temperature 363-433 K, fuel CNG and λ range 3-5. The simulations are generally in good agreement with the experimental data including temperature, pressure, combustion duration and ignition delay and heat release.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Fuels for homogeneous charge compression ignition (HCCI) engines. Automotive fuels survey. Part 6

    Energy Technology Data Exchange (ETDEWEB)

    Van Walwijk, M.

    2001-01-01

    Homogeneous charge compression ignition (HCCI) is a third mode of operation for internal combustion engines, beside spark ignition and conventional compression ignition. This report concentrates on the requirements that HCCI operation puts on fuels for these engines. For readers with limited time available, this summary describes the main findings. Policy makers that need some more background information may turn directly to chapter 7, 'Fuels for HCCI engines'. The rest of this report can be considered as a reference guide for more detailed information. The driving force to investigate HCCI engines is the potential of low emissions and simultaneously high energy efficiency. HCCI is gaining attention the last few years. However, HCCI engines are still in the research phase. After many experiments with prototype engines, people have now started working on computer simulations of the combustion process, to obtain a fundamental understanding of HCCI combustion and to steer future engine developments. In HCCI engines, an air/fuel mixture is prepared before it enters the combustion chamber. The homogeneous mixture is in the combustion chamber compressed to auto-ignition. Unlike in conventional engines, combustion starts at many different locations simultaneously and the speed of combustion is very high, so there is no flame front. Lean air/fuel mixtures (excess air) are used to control combustion speed. Because of the excess air, combustion temperature is relatively low, resulting in low NOx emissions. When the fuel is vaporised to a truly homogeneous mixture, complete combustion results in low particulate emissions. The most important advantages of HCCI engines are: - Emissions of NOx and particulates are very low. - Energy efficiency is high. It is comparable to diesel engines. - Many different fuels (one at a time) can be used in the HCCI concept. There are also some hurdles to overcome: - Controlling combustion is difficult, it complicates engine design

  15. Analysis of a new analytical law of Heat Release Rate (HRR) for Homogeneous Charge Compression Ignition (HCCI) combustion mode versus analytical parameters

    OpenAIRE

    Garcia, Miguel Torres; Jiménez-Espadafor Aguilar, Francisco J.; Becerra Villanueva, José A.; Trujillo, Elisa Carvajal

    2010-01-01

    Abstract Homogeneous charge compression ignition (HCCI) engines produce very low NOx and soot emissions and alsoimprove engine efficiency when compare to conventional spark ignition engines. The combustion process bases on the self-ignition of a homogenous air-fuel mixture without an external ignition source. The gas temperature is very important to initiate the combustion and to promote the appropriate chemical kinetics. As a result, the heat release rate and heat transfer inside ...

  16. A numerical analysis of the effects of a stratified pre-mixture on homogeneous charge compression ignition combustion

    Energy Technology Data Exchange (ETDEWEB)

    Jamsran, Narankhuu; Lim, Ock Taeck [University of Ulsan, Ulsan (Korea, Republic of)

    2012-06-15

    We investigated the efficacy of fuel stratification in a pre-mixture of dimethyl ether (DME) and n-butane, which have different autoignition characteristics, for reducing the pressure rise rate (PRR) of homogeneous charge compression ignition engines. A new chemical reaction model was created by mixing DME and n-butane and compared with existing chemical reaction models to verify the effects observed. The maximum PRR depended on the mixture ratio. When DME was charged with stratification and n-butane was charged with homogeneity, the maximum PRR was the lowest among all the mixtures studied. Calculations were performed using CHEMKIN and modified using SENKIN software.

  17. A numerical analysis of the effects of a stratified pre-mixture on homogeneous charge compression ignition combustion

    International Nuclear Information System (INIS)

    We investigated the efficacy of fuel stratification in a pre-mixture of dimethyl ether (DME) and n-butane, which have different autoignition characteristics, for reducing the pressure rise rate (PRR) of homogeneous charge compression ignition engines. A new chemical reaction model was created by mixing DME and n-butane and compared with existing chemical reaction models to verify the effects observed. The maximum PRR depended on the mixture ratio. When DME was charged with stratification and n-butane was charged with homogeneity, the maximum PRR was the lowest among all the mixtures studied. Calculations were performed using CHEMKIN and modified using SENKIN software

  18. Investigation on effect of equivalence ratio and engine speed on homogeneous charge compression ignition combustion using chemistry based CFD code

    Directory of Open Access Journals (Sweden)

    Ghafouri Jafar

    2014-01-01

    Full Text Available Combustion in a large-bore natural gas fuelled diesel engine operating under Homogeneous Charge Compression Ignition mode at various operating conditions is investigated in the present paper. Computational Fluid Dynamics model with integrated chemistry solver is utilized and methane is used as surrogate of natural gas fuel. Detailed chemical kinetics mechanism is used for simulation of methane combustion. The model results are validated using experimental data by Aceves, et al. (2000, conducted on the single cylinder Volvo TD100 engine operating at Homogeneous Charge Compression Ignition conditions. After verification of model predictions using in-cylinder pressure histories, the effect of varying equivalence ratio and engine speed on combustion parameters of the engine is studied. Results indicate that increasing engine speed provides shorter time for combustion at the same equivalence ratio such that at higher engine speeds, with constant equivalence ratio, combustion misfires. At lower engine speed, ignition delay is shortened and combustion advances. It was observed that increasing the equivalence ratio retards the combustion due to compressive heating effect in one of the test cases at lower initial pressure. Peak pressure magnitude is increased at higher equivalence ratios due to higher energy input.

  19. 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.

  20. Effects of ethanol added fuel on exhaust emissions and combustion in a premixed charge compression ignition diesel engine

    Directory of Open Access Journals (Sweden)

    Kim Yungjin

    2015-01-01

    Full Text Available The use of diesel engines for vehicle has been increasing recently due to its higher thermal efficiency and lower CO2 emission level. However, in the case of diesel engine, NOx increases in a high temperature combustion region and particulate matter is generated in a fuel rich region. Therefore, the technique of PCCI (premixed charge compression ignition is often studied to get the peak combustion temperature down and to make a better air-fuel mixing. However it also has got a limited operating range and lower engine power produced by the wall wetting and the difficulty of the ignition timing control. In this research, the effect of injection strategies on the injected fuel behavior, combustion and emission characteristics in a PCCI engine were investigated to find out the optimal conditions for fuel injection, and then ethanol blended diesel fuel was used to control the ignition timing. As a result, the combustion pressures and ROHR (rate of heat release of the blended fuel became lower, however, IMEP showed fewer differences. Especially in the case of triple injection, smoke could be reduced a little and NOx emission decreased a lot by using the ethanol blended fuel simultaneously without much decreasing of IMEP compared to the result of 100% diesel fuel.

  1. Experimental study of combustion and emission characteristics of ethanol fuelled port injected homogeneous charge compression ignition (HCCI) combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, Rakesh Kumar; Agarwal, Avinash Kumar [Engine Research Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

    2011-04-15

    The homogeneous charge compression ignition (HCCI) is an alternative combustion concept for in reciprocating engines. The HCCI combustion engine offers significant benefits in terms of its high efficiency and ultra low emissions. In this investigation, port injection technique is used for preparing homogeneous charge. The combustion and emission characteristics of a HCCI engine fuelled with ethanol were investigated on a modified two-cylinder, four-stroke engine. The experiment is conducted with varying intake air temperature (120-150 C) and at different air-fuel ratios, for which stable HCCI combustion is achieved. In-cylinder pressure, heat release analysis and exhaust emission measurements were employed for combustion diagnostics. In this study, effect of intake air temperature on combustion parameters, thermal efficiency, combustion efficiency and emissions in HCCI combustion engine is analyzed and discussed in detail. The experimental results indicate that the air-fuel ratio and intake air temperature have significant effect on the maximum in-cylinder pressure and its position, gas exchange efficiency, thermal efficiency, combustion efficiency, maximum rate of pressure rise and the heat release rate. Results show that for all stable operation points, NO{sub x} emissions are lower than 10 ppm however HC and CO emissions are higher. (author)

  2. 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.

  3. Utilization of waste heat from a HCCI (homogeneous charge compression ignition) engine in a tri-generation system

    International Nuclear Information System (INIS)

    The waste heat from exhaust gases and cooling water of Homogeneous charge compression ignition engines (HCCI) are utilized to drive an ammonia-water cogeneration cycle (AWCC) and some heating processes, respectively. The AWCC is a combination of the Rankine cycle and an absorption refrigeration cycle. Considering the chemical kinetic calculations, a single zone combustion model is developed to simulate the natural gas fueled HCCI engine. Also, the performance of AWCC is simulated using the Engineering Equation Solver software (EES). Through combining these two codes, a detailed thermodynamic analysis is performed for the proposed tri-generation system and the effects of some main parameters on the performances of both the AWCC and the tri-generation system are investigated in detail. The cycle performance is then optimized for the fuel energy saving ratio (FESR). The enhancement in the FESR could be up to 28.56%. Under optimized condition, the second law efficiency of proposed system is 5.19% higher than that of the HCCI engine while the reduction in CO2 emission is 4.067% as compared with the conventional separate thermodynamic systems. Moreover, the results indicate that the engine, in the tri-generation system and the absorber, in the bottoming cycle has the most contribution in exergy destruction. - Highlights: • A new thermodynamic tri-generation system is proposed for waste heat recovery of HCCI engine. • A single zone combustion model is developed to simulate the natural gas fueled HCCI engine. • The proposed tri-generation cycle is analyzed from the view points of both first and second laws of thermodynamics. • In the considered cycle, enhancements of 28.56% in fuel energy saving ratio and 5.19% in exergy efficiency are achieved

  4. 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

  5. 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

  6. Miniature free-piston homogeneous charge compression ignition engine-compressor concept - Part I: performance estimation and design considerations unique to small dimensions

    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

    Research and development activities pertaining to the development of a 10 W, homogeneous charge compression ignition free-piston engine-compressor are presented. Emphasis is place upon the miniature engine concept and design rationale. Also, a crankcase-scavenged, two-stroke engine performance estimation method (slider-crank piston motion) is developed and used to explore the influence of engine operating conditions and geometric parameters on power density and establish plausible design conditions. The minimization of small-scale effects such as enhanced heat transfer, is also explored. (author)

  7. Effects of Direct Fuel Injection Strategies on Cycle-by-Cycle Variability in a Gasoline Homogeneous Charge Compression Ignition Engine: Sample Entropy Analysis

    Directory of Open Access Journals (Sweden)

    Jacek Hunicz

    2015-01-01

    Full Text Available In this study we summarize and analyze experimental observations of cyclic variability in homogeneous charge compression ignition (HCCI combustion in a single-cylinder gasoline engine. The engine was configured with negative valve overlap (NVO to trap residual gases from prior cycles and thus enable auto-ignition in successive cycles. Correlations were developed between different fuel injection strategies and cycle average combustion and work output profiles. Hypothesized physical mechanisms based on these correlations were then compared with trends in cycle-by-cycle predictability as revealed by sample entropy. The results of these comparisons help to clarify how fuel injection strategy can interact with prior cycle effects to affect combustion stability and so contribute to design control methods for HCCI engines.

  8. MECHANISM ON DISTRIBUTION OF PILOT FUEL SPRAY AND COMPRESSING IGNITION IN PREMIXED NATURAL GAS ENGINE IGNITED BY PILOT DIESEL

    Institute of Scientific and Technical Information of China (English)

    Yao Chunde; Yao Guangtao; Song Jinou; Wang Yinshan

    2005-01-01

    Numerical simulations of pilot fuel spray and compressing ignition for pre-mixed natural gas ignited by pilot diesel are described. By means of these modeling, the dual fuel and diesel fuel ignition mechanism of some phenomena investigated on an optional engine by technology of high-speed CCD is analyzed. It is demonstrated that the longer delay of ignition in dual fuel engine is not mainly caused by change of the mixture thermodynamics parameters. The analysis results illustrate that the ignition of pre-mixed natural gas ignited by pilot diesel taking place in dual fuel engine is a process of homogenous charge compression ignition.

  9. Use of a single-zone thermodynamic model with detailed chemistry to study a natural gas fueled homogeneous charge compression ignition engine

    International Nuclear Information System (INIS)

    Highlights: ► Auto-ignition characteristics of a natural gas fueled HCCI engine. ► Engine speed had the greatest effect on the auto-ignition process. ► Increases of C2H6 or C3H8 improved the auto-ignition process. ► Engine performance was not sensitive to small changes in C2H6 or C3H8. ► Nitric oxides concentrations decreased as engine speed or EGR level was increased. - Abstract: A single zone thermodynamic model with detailed chemical kinetics was used to simulate a natural gas fueled homogeneous charge compression ignition (HCCI) engine. The model employed Chemkin and used chemical kinetics for natural gas with 53 species and 325 reactions. This simulation was used to complete analyses for a modified 0.4 L single cylinder engine. The engine possessed a compression ratio of 21.5:1, and had a bore and stroke of 86 and 75 mm, respectively. Several sets of parametric studies were completed to investigate the minimal initial temperature, engine performance, and nitric oxide emissions of HCCI engine operation. The results show significant changes in combustion characteristics with varying engine operating conditions. Effects of varying equivalence ratios (0.3–1.0), engine speeds (1000–4000 RPM), EGR (0–40%), and fuel compositions were determined and analyzed in detail. In particular, every 0.1 increase in equivalence ratio or 500 rpm increase in engine speed requires about a 5 K higher initial temperature for complete combustion, and leads to around 0.7 bar increase in IMEP.

  10. 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.

  11. Numerical study of effects of the intermediates and initial conditions on flame propagation in a real homogeneous charge compression ignition engine

    Directory of Open Access Journals (Sweden)

    Zhang Meng

    2014-01-01

    Full Text Available The premixed flame speed under a small four stock homogeneous charge compression ignition engine, fueled with dimethyl ether, was investigated. The effects of intermediate species, initial temperature, initial pressure, exhaust gas recirculation, and equivalence ratio were studied and compared to the baseline condition. Results show that, under all conditions, the flame speeds calculated without intermediates are higher than those which took the intermediates in consideration. Flame speeds increase with the increase of crank angle. The increase rate is divided into three regions and the increase rate is obviously high in the event of low temperature heat release. Initial temperature and pressure only affect the crank angle of flame speed, but have little influence on its value. Equivalence ratio and exhaust gas recirculation ratio do not only distinctly decrease the flame speed, but also advance the crank angle of flame speed.

  12. Effect of main injection timing for controlling the combustion phasing of a homogeneous charge compression ignition engine using a new dual injection strategy

    International Nuclear Information System (INIS)

    Highlights: • A new dual injection concept is developed by minimum geometry modification. • The occurrence of combustion parameters strongly depend on main injection timing. • At higher load, premixed equivalence ratio dominates over main injection timing. • Retarded of main injection timing tends to retard combustion phasing. • Slightly retarded main injection timing is recommended to avoid intense knocking. - Abstract: Homogeneous charge compression ignition combustion of diesel fuel is implemented using a novel dual injection strategy. A new experimental technique is developed to modify a single cylinder direct injection diesel engine to run on homogeneous combustion mode. Effect of main injection timing is investigated covering a range from 26 to 8 crank angle degrees before top dead center with an interval of 3°. Retarded main injection timing is identified as a control strategy for delaying combustion phasing and a means of controlled combustion phasing of direct injection homogeneous charge compression ignition combustion. Two load conditions were investigated and it was observed that at higher load, start of combustion depends more on fuel air equivalence ratio than main injection timing, whereas at low load, it significantly varies with varying main injection timing. Significant improvements in smoke and oxides of nitrogen emissions are observed when compared with the baseline conventional combustion. By studying different combustion parameters, it is observed that there is an improvement in performance and emissions with marginal loss in thermal efficiency when the main injection timing is 20° before top dead center. This is identified as the optimum main injection timing for such homogeneous combustion under the same operating condition

  13. Analysis of Premixed Charge Compression Ignition Combustion with a Sequential Fluid Mechanics-Multizone Chemical Kinetics Model

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S M; Flowers, D L; Espinosa-Loza, F; Babajimopoulos, A; Assanis, D N

    2004-09-30

    We have developed a methodology for analysis of PCCI engines that applies to conditions in which there is some stratification in the air-fuel distribution inside the cylinder at the time of combustion. Our analysis methodology consists of two stages: first, a fluid mechanics code is used to determine temperature and equivalence ratio distributions as a function of crank angle, assuming motored conditions. The distribution information is then used for grouping the mass in the cylinder into a two-dimensional (temperature-equivalence ratio) array of zones. The zone information is then handed on to a detailed chemical kinetics model that calculates combustion, emissions and engine efficiency information. The methodology applies to situations where chemistry and fluid mechanics are weakly linked. The results of the multi-zone model have been compared to the results obtained from a fully integrated code, in which a chemical kinetics code is directly linked into a fluid mechanics code to calculate chemistry in every cell of the grid. The results show that the multi-zone model predicts burn duration and peak cylinder pressure with good accuracy. However, ignition timing predicted by the multi-zone model is sensitive to the transition angle between the fluid mechanics code and the chemical kinetics code. The paper explores the possibility of using three different criteria for determining the transition angle: fraction of heat release at the time of ignition, temperature of the hottest cell at the time of ignition, and a fixed crank angle of transition. The results show that the three criteria have some validity as transition criteria. Further research is necessary to investigate the effect of fuel properties and operating conditions on transition angle.

  14. Experimental and Numerical Study of Jet Controlled Compression Ignition on Combustion Phasing Control in Diesel Premixed Compression Ignition Systems

    Directory of Open Access Journals (Sweden)

    Qiang Zhang

    2014-07-01

    Full Text Available In order to directly control the premixed combustion phasing, a Jet Controlled Compression Ignition (JCCI for diesel premixed compression ignition systems is investigated. Experiments were conducted on a single cylinder natural aspirated diesel engine without EGR at 3000 rpm. Numerical models were validated by load sweep experiments at fixed spark timing. Detailed combustion characteristics were analyzed based on the BMEP of 2.18 bar. The simulation results showed that the high temperature jets of reacting active radical species issued from the ignition chamber played an important role on the onset of combustion in the JCCI system. The combustion of diesel pre-mixtures was initiated rapidly by the combustion products issued from the ignition chamber. Moreover, the flame propagation was not obvious, similar to that in Pre-mixed Charge Compression Ignition (PCCI. Consequently, spark timing sweep experiments were conducted. The results showed a good linear relationship between spark timing in the ignition chamber and CA10 and CA50, which indicated the ability for direct combustion phasing control in diesel PCCI. The NOx and soot emissions gradually changed with the decrease of spark advance angle. The maximum reduction of NOx and soot were both over 90%, and HC and CO emissions were increased.

  15. Investigation on gasoline homogeneous charge compression ignition (HCCI) combustion implemented by residual gas trapping combined with intake preheating through waste heat recovery

    International Nuclear Information System (INIS)

    Highlights: • Combined use of residual gas trapping and intake preheating is explored. • Fuel economy improvement benefits most from changed valve configuration. • Compromise between intake thermal demand and engine efficiency is analyzed. • Intake preheating by waste heat recovery decreases fuel consumption by 8–12%. • Low load boundary is effectively extended to 0.8 bar. - Abstract: Homogeneous charge compression ignition (HCCI) combustion achieved by residual gas trapping suffers from the limitation of the low load extension and fuel economy penalties whilst achieved by intake preheating alone is limited by the high intake thermal requirement and waste heat recovery. In the presented research, systematic engine experiments were carried out on a single cylinder engine on the combined use of residual gas trapping and intake preheating to achieve optimized combustion and better fuel conversion efficiency in the HCCI operational range. The effect of different combinations between residual gas trapping and intake preheating on HCCI combustion was explored and analyzed. It was indicated that the implementation transition from residual gas trapping to intake preheating significantly influenced the fuel economy and emissions. The decreased loss resulting from changed valve configuration contributed much more than half of the fuel economy improvement. The variation in emissions depended both on the combustion temperature influenced by dilution charge and the in-cylinder distribution affected by implementation form. It was also demonstrated that the increased benefit became less when the intake temperature further went up. Thus a relatively reasonable compromise between intake thermal demand and engine efficiency could be achieved to optimize the HCCI combustion by combining waste heat recovery and residual gas trapping. Compared to negative valve overlap method alone, the supplementary of intake preheating by waste heat recovery provided 8–12% fuel economy

  16. 75 FR 47520 - Standards of Performance for Stationary Compression Ignition and Spark Ignition Internal...

    Science.gov (United States)

    2010-08-06

    ... rulemaking published in the Federal Register on June 8, 2010 (75 FR 32612). That notice proposed revisions to... Compression Ignition and Spark Ignition Internal Combustion Engines AGENCY: Environmental Protection Agency... the standards of performance for stationary compression ignition and spark ignition...

  17. 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.

  18. Comparison study on combustion characteristics and emissions of a homogeneous charge compression ignition (HCCI) engine with and without pre-combustion chamber

    International Nuclear Information System (INIS)

    Highlights: • Effect of pre-combustion chamber on HCCI combustion engine was investigated. • HCCI engine with modified chamber has more advanced SOC together with higher IMEP. • Higher level of NO emissions is produced by HCCI combustion with modified chamber. • In modified chamber HCCI engine, both CO and HC emissions decreased drastically. - Abstract: There is an urgent need to develop new combustion strategies such as homogeneous charge compression ignition (HCCI) mode to meet current and future emissions regulations. In this study, experiments and a coupled AVL-CHEMKIN CFD (computational fluid dynamic) model were adopted to compare combustion phasing, engine performance and emissions in term of equivalence ratio for both HCCI combustion engines with and without pre-combustion chamber to investigate the effect of pre-combustion chamber on HCCI combustion engine. Results revealed that with an equivalence ratio of 0.2, HCCI engine with pre-combustion chamber (comet MK.V) tolerates misfiring process, while HCCI engine without pre-combustion chamber (modified chamber) experiences a complete combustion. HCCI engine with modified chamber has higher combustion pressure, narrower heat release rate (HRR), more advanced start of combustion (SOC) and higher indicated mean effective pressure (IMEP) in comparison with comet MK.V chamber. For equivalence ratios between 0.2 and 0.5, the average increase in IMEPs is 49.3%. Furthermore, HCCI engine with modified chamber generates higher work per kg fuel compared to comet MK.V chamber. While a high level of nitrogen oxide (NOx) emissions is produced by HCCI combustion with modified chamber, both carbon monoxide (CO) and hydrocarbon (HC) emissions decreased drastically. In terms of combustion phasing, engine performance and emissions, the HCCI engine with modified combustion chamber is preferred at low equivalence ratios (Φ < 0.3) compared with comet MK.V chamber

  19. 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

  20. Low emissions compression ignited engine technology

    Science.gov (United States)

    Coleman, Gerald N.; Kilkenny, Jonathan P.; Fluga, Eric C.; Duffy, Kevin P.

    2007-04-03

    A method and apparatus for operating a compression ignition engine having a cylinder wall, a piston, and a head defining a combustion chamber. The method and apparatus includes delivering fuel substantially uniformly into the combustion chamber, the fuel being dispersed throughout the combustion chamber and spaced from the cylinder wall, delivering an oxidant into the combustion chamber sufficient to support combustion at a first predetermined combustion duration, and delivering a diluent into the combustion chamber sufficient to change the first predetermined combustion duration to a second predetermined combustion duration different from the first predetermined combustion duration.

  1. Emission of a Dual-Fuel Turbocharged Compression Ignition Engine

    Science.gov (United States)

    Rózycki, Andrzej

    2012-02-01

    The paper describes the results of a four-cylinder dual fuel turbocharged compression ignition engine. The aim of the study was to determine the maximum CNG share in thefuel mixture delivered into the cylinder. Analysis of the investigation results showed that the CNG energy share in the fuel charge delivered into the cylinder can reach 45%. At that level of CNG energy share a 15% reduction in maximum torque is achieved in comparison with the standard fuelling. The unburnt hydrocarbon emission increases significantly. Emissions of other principal pollutants reach values comparable with those obtained at standard fuelling.

  2. THE EFFECT OF COMPRESSION RATIO VARIATIONS ON THE ENGINE PERFORMANCE PARAMETRES IN SPARK IGNITION ENGINES

    Directory of Open Access Journals (Sweden)

    Yakup SEKMEN

    2005-01-01

    Full Text Available Performance of the spark ignition engines may be increased by changing the geometrical compression ratio according to the amount of charging in cylinders. The designed geometrical compression ratio can be realized as an effective compression ratio under the full load and full open throttle conditions since the effective compression ratio changes with the amount of charging into the cylinder in spark ignition engines. So, this condition of the spark ignition engines forces designers to change their geometrical compression ratio according to the amount of charging into the cylinder for improvement of performance and fuel economy. In order to improve the combustion efficiency, fuel economy, power output, exhaust emissions at partial loads, compression ratio must be increased; but, under high load and low speed conditions to prevent probable knock and hard running the compression ratio must be decreased gradually. In this paper, relation of the performance parameters to compression ratio such as power, torque, specific fuel consumption, cylindir pressure, exhaust gas temperature, combustion chamber surface area/volume ratio, thermal efficiency, spark timing etc. in spark ignition engines have been investigated and using of engines with variable compression ratio is suggested to fuel economy and more clear environment.

  3. The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

    Energy Technology Data Exchange (ETDEWEB)

    Zylstra, A. B., E-mail: zylstra@mit.edu; Frenje, J. A.; Séguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Li, C. K.; Manuel, M. J.-E.; Petrasso, R. D.; Sinenian, N.; Sio, H. W. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Friedrich, S.; Bionta, R.; Atherton, J.; Barrios, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2014-11-15

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D{sup 3}He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D{sup 3}He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2× higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (ρR) and the shell center-of-mass radius (R{sub cm}) from the downshift of the shock-produced D{sup 3}He protons. The observed ρR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time (“short-coast”), while longer-coasting implosions have lower ρR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (∼800 ps) than in the short-coast (∼400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel ρR.

  4. Development of a simulation model for compression ignition engine running with ignition improved blend

    OpenAIRE

    Sudeshkumar Ponnusamy Moranahalli; Devaradjane Gopalakrishnan

    2011-01-01

    Department of Automobile Engineering, Anna University, Chennai, India. The present work describes the thermodynamic and heat transfer models used in a computer program which simulates the diesel fuel and ignition improver blend to predict the combustion and emission characteristics of a direct injection compression ignition engine fuelled with ignition improver blend using classical two zone approach. One zone consists of pure air called non burning zone and other zone consist of fuel a...

  5. Approaches to Improve Mixing in Compression Ignition Engines

    Energy Technology Data Exchange (ETDEWEB)

    Boot, M.D.

    2010-04-20

    This thesis presents three approaches to suppress soot emissions in compression ignition (CI) engines. First, a fuel chemistry approach is proposed. A particular class of fuels - cyclic oxygenates - is identified which is capable of significantly reducing engine-out soot emissions. By means of experiments in 'closed' and optical engines, as well as on an industrial burner, two possible mechanisms are identified that could account for the observed reduction in soot: a) an extended ignition delay (ID) and b) a longer flame lift-length (FLoL). Further analysis of the available data suggests that both mechanisms are related to the inherently low reactivity of the fuel class in question. These findings are largely in line with data found in literature. In the second approach, it is attempted to reduce soot by adopting an alternative combustion concept: early direct injection premixed charge compression ignition (EDI PCCI). In this concept, fuel is injected relatively early in the compression stroke instead of conventional, close to top-dead-center (TDC), injection schemes. While the goal of soot reduction can indeed be achieved via this approach, an important drawback must be addressed before this concept can be considered practically viable. Due to the fact that combustion chamber temperature and pressure is relatively low early in the compression stroke, fuel impingement against the cylinder liner (wall-wetting) often occurs. Consequently, high levels of unburned hydrocarbons (UHC), oil dilution and poor efficiency are observed. Several strategies, combining a limited engine modification with dedicated air management and fueling settings, are investigated to tackle this drawback. All of these strategies, and especially their combination, resulted in significantly lower UHC emissions and improved fuel economy. Although UHC emissions are typically a tell-tale sign of wall-wetting, as mentioned earlier, the relation between these two has long been hypothetical

  6. Gasoline surrogate modeling of gasoline ignition in a rapid compression machine and comparison to experiments

    Energy Technology Data Exchange (ETDEWEB)

    Mehl, M; Kukkadapu, G; Kumar, K; Sarathy, S M; Pitz, W J; Sung, S J

    2011-09-15

    The use of gasoline in homogeneous charge compression ignition engines (HCCI) and in duel fuel diesel - gasoline engines, has increased the need to understand its compression ignition processes under engine-like conditions. These processes need to be studied under well-controlled conditions in order to quantify low temperature heat release and to provide fundamental validation data for chemical kinetic models. With this in mind, an experimental campaign has been undertaken in a rapid compression machine (RCM) to measure the ignition of gasoline mixtures over a wide range of compression temperatures and for different compression pressures. By measuring the pressure history during ignition, information on the first stage ignition (when observed) and second stage ignition are captured along with information on the phasing of the heat release. Heat release processes during ignition are important because gasoline is known to exhibit low temperature heat release, intermediate temperature heat release and high temperature heat release. In an HCCI engine, the occurrence of low-temperature and intermediate-temperature heat release can be exploited to obtain higher load operation and has become a topic of much interest for engine researchers. Consequently, it is important to understand these processes under well-controlled conditions. A four-component gasoline surrogate model (including n-heptane, iso-octane, toluene, and 2-pentene) has been developed to simulate real gasolines. An appropriate surrogate mixture of the four components has been developed to simulate the specific gasoline used in the RCM experiments. This chemical kinetic surrogate model was then used to simulate the RCM experimental results for real gasoline. The experimental and modeling results covered ultra-lean to stoichiometric mixtures, compressed temperatures of 640-950 K, and compression pressures of 20 and 40 bar. The agreement between the experiments and model is encouraging in terms of first

  7. Capacitor discharge ignition system having a charging control means

    Energy Technology Data Exchange (ETDEWEB)

    Fitzner, A.O.

    1984-02-28

    The invention provides charging control circuitry for a capacitor descharge ignition system having power capacitors connected to be discharged by main electronic switches such as SCR's into ignition transformers to sequentially fire the engine's spark plugs. The charging control circuits each include a charging SCR to limit charging current flow to the main capacitor, unless a discharge pulse into the ignition transformer has occurred in the recent past. Thus if a short circuit in either the main capacitor or main SCR in one of the ignition circuits prevents that ignition circuit form properly functioning, the charging SCR will limit the flow of charging current to the defective circuit and allow the other ignition circuit to receive charging current. The gate of the charging SCR is controlled by an amplified signal from a memory capacitor which is charged by the discharge pulse from the corresponding ignition circuit. The same memory capacitor also provides power to drive an indicator such as a light emitting diode.

  8. Application of Dimethyl Ether in Compression Ignition Engines

    DEFF Research Database (Denmark)

    Hansen, Kim Rene

    -Marathon. The diesel engine test results from 1995 showed that DME is a superb diesel fuel. DME is easy to ignite by compression ignition and it has a molecular structure that results in near-zero emission of particulates when burned. These are features of a fuel that are highly desirable in a diesel engine....... The challenges with DME as a diesel engine fuel are mainly related to poor lubricity and incompatibility with a range of elastomers commonly used for seals in fuel injection systems. This means that although DME burns well in a diesel engine designing a fuel injection system for DME is challenging. Since...

  9. Effects of operating parameters on nitrogen oxides emissions for a natural gas fueled homogeneous charged compression ignition engine (HCCI): Results from a thermodynamic model with detailed chemistry

    International Nuclear Information System (INIS)

    Highlights: ► Nitrogen oxides emissions were determined for a natural gas fueled HCCI engine. ► The thermal NO mechanism accounts for the most of the NOx (around 70%). ► Among the parameters examined, equivalence ratio had the greatest effect on NOx. ► Reduction of NOx was due to decreased times at high temperatures. ► The nitrogen oxides emissions were reduced with increasing EGR level. -- Abstract: Past numerical studies on natural gas HCCI engines have provided few thorough analyses of the effects of operating parameters on nitrogen oxides (referring to the mixture of nitric oxide and nitrogen dioxide). A single zone thermodynamic model with detailed chemical kinetics was used to determine the effect of operating parameters on nitrogen oxides emissions. The model employed Chemkin and used chemical kinetics for natural gas with 53 species and 325 reactions. The simulation was conducted for a modified 0.4 l single cylinder engine, which possessed a compression ratio of 21.5:1, and had a bore and stroke of 86 and 75 mm, respectively. Several sets of parametric studies were completed to investigate the effect of engine load (imep = 200–600 kPa), speed (600–3000 RPM), equivalence ratio (0.3–1.0), EGR level (0–40%), temperature at IVC (390–460 K), and fuel compositions (0–10% C2H6) on nitrogen oxides emissions. Contributions of different NOx mechanisms have been examined, and the thermal mechanism accounts for over 70% of the total NOx at most of the conditions. The results show significant changes in nitrogen oxides concentrations with varying engine operating conditions. These changes are shown to be strongly dependent on the chemical kinetics and the resulting differences in gas temperature profiles. For this particular study, 50% reduction in nitrogen oxides emissions could result from a load (imep) decrease from 300 kPa to 200 kPa, or an EGR level increase from 0% to 20%.

  10. Vehicle Integrated Photovoltaics for Compression Ignition Vehicles: An Experimental Investigation of Solar Alkaline Water Electrolysis for Improving Diesel Combustion and a Solar Charging System for Reducing Auxiliary Engine Loads

    Science.gov (United States)

    Negroni, Garry Inocentes

    Vehicle-integrated photovoltaic electricity can be applied towards aspiration of hydrogen-oxygen-steam gas produced through alkaline electrolysis and reductions in auxiliary alternator load for reducing hydrocarbon emissions in low nitrogen oxide indirect-injection compression-ignition engines. Aspiration of 0.516 ± 0.007 liters-per-minute of gas produced through alkaline electrolysis of potassium-hydroxide 2wt.% improves full-load performance; however, part-load performance decreases due to auto-ignition of aspirated gas prior to top-dead center. Alternator load reductions offer improved part-load and full-load performance with practical limitations resulting from accessory electrical loads. In an additive approach, solar electrolysis can electrochemically convert solar photovoltaic electricity into a gas comprised of stoichiometric hydrogen and oxygen gas. Aspiration of this hydrogen-oxygen gas enhances combustion properties decreasing emissions and increased combustion efficiency in light-duty diesel vehicles. The 316L stainless steel (SS) electrolyser plates are arranged with two anodes and three cathodes space with four bipolar plates delineating four stacks in parallel with five cells per stack. The electrolyser was tested using potassium hydroxide 2 wt.% and hydronium 3wt.% at measured voltage and current inputs. The flow rate output from the reservoir cell was measured in parallel with the V and I inputs producing a regression model correlating current input to flow rate. KOH 2 wt.% produced 0.005 LPM/W, while H9O44 3 wt.% produced less at 0.00126 LPM/W. In a subtractive approach, solar energy can be used to charge a larger energy storage device, as is with plug-in electric vehicles, in order to alleviate the engine of the mechanical load placed upon it by the vehicles electrical accessories through the alternator. Solar electrolysis can improve part-load emissions and full-load performance. The average solar-to-battery efficiency based on the OEM rated

  11. Modeling Ignition and Combustion in Direct Injection Compression Ignition Engines Employing Very Early Injection Timing

    Science.gov (United States)

    Miyamoto, Takeshi; Tsurushima, Tadashi; Shimazaki, Naoki; Harada, Akira; Sasaki, Satoru; Hayashi, Koichi; Asaumi, Yasuo; Aoyagi, Yuzo

    An ignition and combustion model has been developed to predict the heat release rate in direct injection compression ignition engines employing very early injection timing. The model describes the chemical reactions, including low-temperature oxidation. The KIVA II computer code was modified with the present ignition and combustion model. The numerical results indicate that the model developed in this work reproduces major features of two-stage autoignition, as well as experimentally observed trends in NOx and unburned fuel emissions. The computational results show that fuel injection timing significantly influences NOx emissions. Results also indicate that fuel droplets that enter the squish region possibly become unburned fuel emissions. Some graphical results demonstrate the relationships among the in-cylinder fuel spray distributions, fuel-air equivalence ratio, temperature, and mass fractions of NO and unburned fuel.

  12. Combustion of CNG in Charged Spark Ignition Engines

    Science.gov (United States)

    Mitianiec, Wladyslaw

    2009-12-01

    The paper describes mixing of injected CNG with air and combustion process in spark ignition internal combustion engine. Because of higher ignition temperature of CNG the SI engines have more effective ignition system than conventional engines. The gas motion, turbulence, charge temperature and obviously electrical energy of the ignition coil have a big influence on the ignition and burning process in the combustion chamber. The paper includes theoretical and experimental investigations of ignition process in the high charged SI engines with direct CNG injection by using LES technique in KIVA program. Simulation of CNG combustion in the caloric chamber was carried in the environment of OpenFOAM program with LES model and also the experimental test was carried out for comparison of results in the chamber with the same geometry. The influence of the "tumble" and "swirl" on the sparking is shown by modelling of this process in premixed charge by using LES technique. The charge motion and also considerably turbulence effect influence strongly on the ignition process.

  13. Compression Process of Pore inside Explosive Charge in a Warhead under Launching Load

    OpenAIRE

    Li, W; Yan, H; Q. Zhang; Y.H. Ji

    2010-01-01

    In this paper, the compression process of the pore inside explosive charge in a warhead under launching load is simulated and its influence on premature explosion is discussed. The relationship between the pore compression, distortion, and the form of 'igniting hot spot' has been established. The analysis of result indicates that the stress wave in the explosive charge developed due to launching load is a key factor in the pore compression process. The volume change of the pore, which is rela...

  14. Optimizing the Compression Ratio of Compression Ignition Engine Fuelled With Esters of Crude Rice Bran Oil

    Directory of Open Access Journals (Sweden)

    Mohit Vasudeva

    2013-10-01

    Full Text Available Experiments were carried out on a single cylinder four stroke variable compression ratio compression ignition engine with an attempt to figure out the optimum compression ratio fuelled with blend of methyl ester of crude rice bran oil with diesel. A 2-step transesterification reaction was carried out for the preparation of the methyl ester of crude rice bran oil. Experiments were carried out at different compression ratios ranging from 12 to 18. A B20 blend was used as fuel for conducting the experiments. At a compression ratio of 14 results showed significant improvement in the performance characteristics. Highest brake thermal efficiency along with lowest specific fuel consumption was observed at a compression ratio of 14. Compression ratio above and below 14 showed drop in the brake thermal efficiency and increase in specific fuel consumption.

  15. Development of a simulation model for compression ignition engine running with ignition improved blend

    Directory of Open Access Journals (Sweden)

    Sudeshkumar Ponnusamy Moranahalli

    2011-01-01

    Full Text Available Department of Automobile Engineering, Anna University, Chennai, India. The present work describes the thermodynamic and heat transfer models used in a computer program which simulates the diesel fuel and ignition improver blend to predict the combustion and emission characteristics of a direct injection compression ignition engine fuelled with ignition improver blend using classical two zone approach. One zone consists of pure air called non burning zone and other zone consist of fuel and combustion products called burning zone. First law of thermodynamics and state equations are applied in each of the two zones to yield cylinder temperatures and cylinder pressure histories. Using the two zone combustion model the combustion parameters and the chemical equilibrium composition were determined. To validate the model an experimental investigation has been conducted on a single cylinder direct injection diesel engine fuelled with 12% by volume of 2- ethoxy ethanol blend with diesel fuel. Addition of ignition improver blend to diesel fuel decreases the exhaust smoke and increases the thermal efficiency for the power outputs. It was observed that there is a good agreement between simulated and experimental results and the proposed model requires low computational time for a complete run.

  16. Direct Injection Compression Ignition Diesel Automotive Technology Education GATE Program

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Carl L

    2006-09-25

    The underlying goal of this prqject was to provide multi-disciplinary engineering training for graduate students in the area of internal combustion engines, specifically in direct injection compression ignition engines. The program was designed to educate highly qualified engineers and scientists that will seek to overcome teclmological barriers preventing the development and production of cost-effective high-efficiency vehicles for the U.S. market. Fu1iher, these highly qualified engineers and scientists will foster an educational process to train a future workforce of automotive engineering professionals who are knowledgeable about and have experience in developing and commercializing critical advanced automotive teclmologies. Eight objectives were defmed to accomplish this goal: 1. Develop an interdisciplinary internal co1nbustion engine curriculum emphasizing direct injected combustion ignited diesel engines. 2. Encourage and promote interdisciplinary interaction of the faculty. 3. Offer a Ph.D. degree in internal combustion engines based upon an interdisciplinary cuniculum. 4. Promote strong interaction with indusuy, develop a sense of responsibility with industry and pursue a self sustaining program. 5. Establish collaborative arrangements and network universities active in internal combustion engine study. 6. Further Enhance a First Class educational facility. 7. Establish 'off-campus' M.S. and Ph.D. engine programs of study at various indusuial sites. 8. Extend and Enhance the Graduate Experience.

  17. 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

    This report summarizes activities related to the revised STATEMENT OF PROJECT OBJECTIVES (SOPO) dated June 2010 for the Development of High-Efficiency Clean Combustion engine Designs for Spark-Ignition and Compression-Ignition Internal Combustion Engines (COOPERATIVE AGREEMENT NUMBER DE-FC26-05NT42415) project. In both the spark- (SI) and compression-ignition (CI) development activities covered in this program, the goal was to develop potential production-viable internal combustion engine system technologies that both reduce fuel consumption and simultaneously met exhaust emission targets. To be production-viable, engine technologies were also evaluated to determine if they would meet customer expectations of refinement in terms of noise, vibration, performance, driveability, etc. in addition to having an attractive business case and value. Prior to this activity, only proprietary theoretical / laboratory knowledge existed on the combustion technologies explored The research reported here expands and develops this knowledge to determine series-production viability. Significant SI and CI engine development occurred during this program within General Motors, LLC over more than five years. In the SI program, several engines were designed and developed that used both a relatively simple multi-lift valve train system and a Fully Flexible Valve Actuation (FFVA) system to enable a Homogeneous Charge Compression Ignition (HCCI) combustion process. Many technical challenges, which were unknown at the start of this program, were identified and systematically resolved through analysis, test and development. This report documents the challenges and solutions for each SOPO deliverable. As a result of the project activities, the production viability of the developed clean combustion technologies has been determined. At this time, HCCI combustion for SI engines is not considered production-viable for several reasons. HCCI combustion is excessively sensitive to control variables

  18. Effect of Exhaust Gas Recirculation on the Dual Fuel Combustion of Gasoline and CNG by Compression Ignition

    OpenAIRE

    A. Rashid A. Aziz; Raja Shahzad; Noraz Al-Khairi; P. Naveenchandran

    2011-01-01

    Homogeneous Charge Compression Ignition (HCCI) is a combustion process that promises the combination of diesel like efficiencies and very low NOx emissions. The major issues with HCCI are high heat release rates, lack of combustion control and high CO and HC emissions. Operating HCCI with two fuels of different properties and recirculation of exhaust gases are effective strategies of promoting and controlling autoignition. This study discusses the effects of EGR on the combustion characterist...

  19. EXPERIMENTAL STUDIES ON PERFORMANCE CHARACTERISTICS OF THERMO - ELECTRIC GENERATOR USED IN COMPRESSION IGNITION ENGINES

    OpenAIRE

    Dr. G. Ganesh Kumar; Dr. K. Sridhar, V. Sampath

    2015-01-01

    This paper deals with the study on performance characteristics of thermo - electric generator modules used in Compression Ignition engines for production of an electrical energy. E xhaustive studies are being done in utiliz ing th e heat rejected through exhaust gases of a Compression Ignition engine working in a cycle to raise the overall efficiency. It is observed that about 35 – 45 % of heat generated is being ...

  20. Internal combustion engines a detailed introduction to the thermodynamics of spark and compression ignition engines, their design and development

    CERN Document Server

    Benson, Rowland S

    1979-01-01

    Internal Combustion of Engines: A Detailed Introduction to the Thermodynamics of Spark and Compression Ignition Engines, Their Design and Development focuses on the design, development, and operations of spark and compression ignition engines. The book first describes internal combustion engines, including rotary, compression, and indirect or spark ignition engines. The publication then discusses basic thermodynamics and gas dynamics. Topics include first and second laws of thermodynamics; internal energy and enthalpy diagrams; gas mixtures and homocentric flow; and state equation. The text ta

  1. A Preliminary Motion-picture Study of Combustion in a Compression-ignition Engine

    Science.gov (United States)

    Buckley, E C; Waldron, C D

    1934-01-01

    Motion pictures were taken at 1,850 frames per second of the spray penetration and combustion occurring in the N.A.C.A. combustion apparatus arranged to operate as a compression-ignition engine. Indicator cards were taken simultaneously with the motion pictures by means of the N.A.C.A. optical indicator. The motion pictures showed that when ignition occurred during injection it started in the spray envelope. If ignition occurred after injection cut-off, however, and after considerable mixing had taken place, it was impossible to predict where the ignition would start. The pictures also showed that ignition usually started at several points in the combustion chamber. With this apparatus, as the injection advance angle increased from 0 degrees to 40 degrees before top center, the rate of flame spread increased and the duration of the burning decreased.

  2. Study of Knocking Effect in Compression Ignition Engine with Hydrogen as a Secondary Fuel

    OpenAIRE

    R. Sivabalakrishnan; Jegadheesan, C.

    2014-01-01

    The aim of this project is detecting knock during combustion of biodiesel-hydrogen fuel and also the knock is suppressed by timed injection of diethyl ether (DEE) with biodiesel-hydrogen fuel for different loads. Hydrogen fuel is an effective alternate fuel in making a pollution-free environment with higher efficiency. The usage of hydrogen in compression ignition engine leads to production of knocking or detonation because of its lower ignition energy, wider flammability range, and shorter q...

  3. Study of ignition in a high compression ratio SI (spark ignition) methanol engine using LES (large eddy simulation) with detailed chemical kinetics

    International Nuclear Information System (INIS)

    Methanol has been recently used as an alternative to conventional fuels for internal combustion engines in order to satisfy some environmental and economical concerns. In this paper, the ignition in a high compression ratio SI (spark ignition) methanol engine was studied by using LES (large eddy simulation) with detailed chemical kinetics. A 21-species, 84-reaction methanol mechanism was adopted to simulate the auto-ignition process of the methanol/air mixture. The MIT (minimum ignition temperature) and MIE (minimum ignition energy) are two important properties for designing safety standards and understanding the ignition process of combustible mixtures. The effects of the flame kernel size, flame kernel temperature and equivalence ratio were also examined on MIT, MIE and IDP (ignition delay period). The methanol mechanism was validated by experimental test. The simulated results showed that the flame kernel size, temperature and energy dramatically affected the values of the MIT, MIE and IDP for a methanol/air mixture, the value of the ignition delay period was not only related to the flame kernel energy, but also to the flame kernel temperature. - Highlights: • We used LES (large eddy simulation) coupled with detailed chemical kinetics to simulate methanol ignition. • The flame kernel size and temperature affected the minimum ignition temperature. • The flame kernel temperature and energy affected the ignition delay period. • The equivalence ratio of methanol–air mixture affected the ignition delay period

  4. Exhaust Emissions Measured Under Real Traffic Conditions from Vehicles Fitted with Spark Ignition and Compression Ignition Engines

    Science.gov (United States)

    Merkisz, Jerzy; Lijewski, Piotr; Fuć, Paweł

    2011-06-01

    The tests performed under real traffic conditions provide invaluable information on the relations between the engine parameters, vehicle parameters and traffic conditions (traffic congestion) on one side and the exhaust emissions on the other. The paper presents the result of road tests obtained in an urban and extra-urban cycles for vehicles fitted with different engines, spark ignition engine and compression ignition engine. For the tests a portable emission analyzer SEMTECH DS. by SENSORS was used. This analyzer provides online measurement of the concentrations of exhaust emission components on a vehicle in motion under real traffic conditions. The tests were performed in city traffic. A comparative analysis has been presented of the obtained results for vehicles with individual powertrains.

  5. 76 FR 37953 - Standards of Performance for Stationary Compression Ignition and Spark Ignition Internal...

    Science.gov (United States)

    2011-06-28

    ... stationary spark ignition (SI) engines (73 FR 3567). While these regulations are distinct from the standards.... On June 8, 2010 (75 FR 32612), the EPA proposed amendments to the standards of performance for...). The NSPS were originally promulgated on July 11, 2006 (71 FR 39153). New source performance...

  6. 75 FR 32611 - Standards of Performance for Stationary Compression Ignition and Spark Ignition Internal...

    Science.gov (United States)

    2010-06-08

    ... containing separate standards of performance for stationary spark ignition (SI) engines. (73 FR 3567) While... were initially published on July 11, 2006 (71 FR 39153). New source performance standards implement... noted in the proposed rule (70 FR 39870) that it was reviewing the possibility of promulgating...

  7. Ignition properties of methane/hydrogen mixtures in a rapid compression machine

    NARCIS (Netherlands)

    Gersen, S.; Anikin, N. B.; Mokhov, A. V.; Levinsky, H. B.

    2008-01-01

    We investigate changes in the combustion behavior of methane, the primary component of natural gas, upon hydrogen addition by characterizing the autoignition behavior of methane/hydrogen mixtures in a rapid compression machine (RCM). Ignition delay times were measured under stoichiometric conditions

  8. A 50 cc Two-Stroke DI Compression Ignition Engine Fuelled by DME

    DEFF Research Database (Denmark)

    Hansen, Kim Rene; Nielsen, Claus Suldrup; Sorenson, Spencer C;

    2008-01-01

    The low auto-ignition temperature, rapid evaporation and high cetane number of dimethyl ether (DME) enables the use of low-pressure direct injection in compression ignition engines, thus potentially bringing the cost of the injection system down. This in turn holds the promise of bringing CI...... efficiency to even the smallest engines. A 50cc crankcase scavenged two-stroke CI engine was built based on moped parts. The major alterations were a new cylinder head and a 100 bar DI system using a GDItype injector. Power is limited by carbon monoxide emission but smoke-free operation and NOx less than 200...

  9. Numerical parametric investigations of a gasoline fuelled partially-premixed compression-ignition engine

    Energy Technology Data Exchange (ETDEWEB)

    Nemati, Arash [Islamic Azad University, Miyaneh Branch, Miyaneh (Iran, Islamic Republic of); Khalilarya, Shahram; Jafarmadar, Samad; Khatamenjhad, Hassan [Department of Mechanical Engineering, Urmia University, Urmia (Iran, Islamic Republic of); Fathi, Vahid [Islamic Azad University, Ajagshir Branch, Ajabshir (Iran, Islamic Republic of)

    2011-07-01

    Parametric studies of a heavy duty direct injection (DI) gasoline fueled compression ignition (CI) engine combustion are presented. Gasoline because of its higher ignition delay has much lower soot emission in comparison with diesel fuel. Using double injection strategy reduces the maximum heat release rate that leads to nitrogen oxides (NOx) emission reduction. A three dimensional computational fluid dynamics (CFD) code was employed and compared with experimental data. The model results show a good agreement with experimental data. The effect of injection characteristics such as, injection duration, main SOI timing, and nozzle hole size investigated on combustion and emissions.

  10. Numerical parametric investigation of a gasoline fuelled partially-premixed compression-ignition engine

    Directory of Open Access Journals (Sweden)

    Arash Nemati, Shahram Khalilarya, Samad Jafarmadar, Hassan Khatamnejhad, Vahid Fathi

    2011-07-01

    Full Text Available Parametric studies of a heavy duty direct injection (DI gasoline fueled compression ignition (CI engine combustion are presented. Gasoline because of its higher ignition delay has much lower soot emission in comparison with diesel fuel. Using double injection strategy reduces the maximum heat release rate that leads to nitrogen oxides (NOx emission reduction. A three dimensional computational fluid dynamics (CFD code was employed and compared with experimental data. The model results show a good agreement with experimental data. The effect of injection characteristics such as, injection duration, main SOI timing, and nozzle hole size investigated on combustion and emissions.

  11. Compression Process of Pore inside Explosive Charge in a Warhead under Launching Load

    Directory of Open Access Journals (Sweden)

    W. Li

    2010-04-01

    Full Text Available In this paper, the compression process of the pore inside explosive charge in a warhead under launching load is simulated and its influence on premature explosion is discussed. The relationship between the pore compression, distortion, and the form of 'igniting hot spot' has been established. The analysis of result indicates that the stress wave in the explosive charge developed due to launching load is a key factor in the pore compression process. The volume change of the pore, which is related to its original volume, is a major factor affecting the form of 'ignition hot spot'. It appears that a specific size of the pore may not lead to the premature explosion of explosive charge in a warhead under launching load. The quantitative relationship between the dangerous size range of the pore and the launching load is a core research subject of warhead safety during launching. With this objective, numerical computing was undertaken to assess the pore's distortion parameter inside the explosive charge of a warhead, and generate database for warhead safety under launching load.Defence Science Journal, 2010, 60(3, pp.244-250, DOI:http://dx.doi.org/10.14429/dsj.60.349

  12. A DETAILED EXPERIMENTAL INVESTIGATION ON HOT AIR ASSISTED TURPENTINE DIRECT INJECTED COMPRESSION IGNITION ENGINE

    Directory of Open Access Journals (Sweden)

    KARTHIKEYAN.R,

    2010-10-01

    Full Text Available In the present investigation, a diesel engine modified for turpentine direct injection (TDI has been tested to study turpentine oil behavior in compression ignition engine. Since, turpentine possesses low cetane number fails to auto ignite while DI. Hence, the test engine was modified to supply hot air during suction stroke, whichhelps to auto-ignite the injected turpentine. The engine with this facility was operated using turpentine under various load conditions and at various intake temperatures. The results of the investigation were proved that turpentine could be direct injectable in a regular diesel engine after little engine modification. This method showed almost same BTE at full load compared to standard diesel operation. Except NOx emission other emissions were found closer to diesel baseline operation. This mode offered almost 50% smoke free operation at all loads compared to standard diesel operation. Also, this method successfully proved the complete replacement of diesel fuel by turpentine oil.

  13. A Multicomponent Blend as a Diesel Fuel Surrogate for Compression Ignition Engine Applications

    Energy Technology Data Exchange (ETDEWEB)

    Pei, Yuanjiang; Mehl, Marco; Liu, Wei; Lu, Tianfeng; Pitz, William J.; Som, Sibendu

    2015-05-12

    A mixture of n-dodecane and m-xylene is investigated as a diesel fuel surrogate for compression ignition engine applications. Compared to neat n-dodecane, this binary mixture is more representative of diesel fuel because it contains an alkyl-benzene which represents an important chemical class present in diesel fuels. A detailed multi-component mechanism for n-dodecane and m-xylene was developed by combining a previously developed n-dodecane mechanism with a recently developed mechanism for xylenes. The xylene mechanism is shown to reproduce experimental ignition data from a rapid compression machine and shock tube, speciation data from the jet stirred reactor and flame speed data. This combined mechanism was validated by comparing predictions from the model with experimental data for ignition in shock tubes and for reactivity in a flow reactor. The combined mechanism, consisting of 2885 species and 11754 reactions, was reduced to a skeletal mechanism consisting 163 species and 887 reactions for 3D diesel engine simulations. The mechanism reduction was performed using directed relation graph (DRG) with expert knowledge (DRG-X) and DRG-aided sensitivity analysis (DRGASA) at a fixed fuel composition of 77% of n-dodecane and 23% m-xylene by volume. The sample space for the reduction covered pressure of 1 – 80 bar, equivalence ratio of 0.5 – 2.0, and initial temperature of 700 – 1600 K for ignition. The skeletal mechanism was compared with the detailed mechanism for ignition and flow reactor predictions. Finally, the skeletal mechanism was validated against a spray flame dataset under diesel engine conditions documented on the Engine Combustion Network (ECN) website. These multi-dimensional simulations were performed using a Representative Interactive Flame (RIF) turbulent combustion model. Encouraging results were obtained compared to the experiments with regards to the predictions of ignition delay and lift-off length at different ambient temperatures.

  14. EXPERIMENTAL STUDIES ON PERFORMANCE CHARACTERISTICS OF THERMO - ELECTRIC GENERATOR USED IN COMPRESSION IGNITION ENGINES

    Directory of Open Access Journals (Sweden)

    Dr. G. Ganesh Kumar

    2015-06-01

    Full Text Available This paper deals with the study on performance characteristics of thermo - electric generator modules used in Compression Ignition engines for production of an electrical energy. E xhaustive studies are being done in utiliz ing th e heat rejected through exhaust gases of a Compression Ignition engine working in a cycle to raise the overall efficiency. It is observed that about 35 – 45 % of heat generated is being wasted through exhaust gases. Hence, an attempt is made to utilize the energy lost in exhaust gases to recharge the battery without effecting the performance of an engine. An experimental set up was designed and fabricated to make the performance test for utilization of exhaust gases. Further, the performance characteristics of the thermo - electric generator consisting of thermo electric modules are studied in detail. The thermal energy from temperature gradient is converted into electrical energy by using the working principle of Seebeck and Pelt i er Effect s

  15. An investigation of partially premixed compression ignition combustion using gasoline and spark assistance

    OpenAIRE

    Benajes Calvo, Jesus Vicente; García Martínez, Antonio; Doménech Llopis, Vicente; Durret, Russell

    2013-01-01

    Nowadays the automotive scientific community and companies are focusing part of their efforts on the investigation of new combustion modes in Compression Ignition (Cl) engines, mainly based on the use of locally lean air fuel mixtures. This characteristic, combined with exhaust gas recirculation, provides low combustion temperatures that reduce pollutant formation. However these combustion concepts have some shortcomings, related to combustion phasing control and combustion stability under th...

  16. Influence of the molecular structure of biofuels on combustion in a compression ignition engine

    OpenAIRE

    Schönborn, A

    2009-01-01

    This thesis presents an experimental study on the influence of the molecular structure of potential biofuels on combustion in a compression ignition engine. The molecular structure of a fuel is amongst the most fundamental parameter controlling its physical and chemical characteristics, and is thus critical to the combustion process within an engine. The approach employed in this work was to study the combustion of several individual molecules in a series of experiments whilst var...

  17. Future Combustion Technology for Synthetic and Renewable Fuels in Compression Ignition Engines (REFUEL) - Final report

    OpenAIRE

    Aakko-Saksa, Päivi; Brink, Anders; Happonen, Matti; Heikkilä, Juha; Hulkkonen, Tuomo; Imperato, Matteo; Kaario, Ossi; Koponen, Päivi; Larmi, Martti; Lehto, Kalle; Murtonen, Timo; Sarjovaara, Teemu; Tilli, Aki; Väisänen, Esa

    2012-01-01

    This domestic project, Future Combustion Technology for Synthetic and Renewable Fuels in Compression Ignition Engines (ReFuel), was part of a Collaborative Task "Future Combustion Technology for Synthetic and Renewable Fuels in Transport" of International Energy Agency (IEA) Combustion Agreement. This international Collaborative Task is coordinated by Finland. The three-year (2009-2011) project was a joint research project with Aalto University (Aalto), Tampere University of Technology (TUT)...

  18. Numerical study on the compression ignition of a porous medium engine

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Homogeneous and stable combustion can be realized in a porous medium (PM) engine where a chemically inert PM is mounted in the combustion chamber. To understand the mechanism of the PM engine, we simulated the working process of a PM engine fueled with natural gas (CH4) using an improved version of KIVA-3V and investigated the effects of the initial PM temperature, the PM structure as well as the fuel injection timing on the compression ignition of the engine. The im- proved version of KIVA-3V was verified by simulating the experiment of Zhdanok et al. for the superadiabatic combustion of CH4-air mixtures under filtration in a packed bed. The numerical results are in good agreement with experimental data for the speed of combustion wave. Computational results for the PM engine show that the initial PM temperature is the key factor in guaranteeing the onset of com- pression ignition of the PM engine at a given compression ratio. The PM structure affects greatly both convective heat transfer between the gas and solid phase in the PM and the dispersion effect of the PM. Pore diameter of the PM is a crucial factor in determining the realization of combustion in the PM engine. Over-late fuel injec- tion timing (near TDC) cannot assure a compression ignition of the PM engine.

  19. THE EFFECT OF VARIABLE COMPRESSION RATIO ON FUEL CONSUMPTION IN SPARK IGNITION ENGINES

    Directory of Open Access Journals (Sweden)

    Yakup SEKMEN

    2002-02-01

    Full Text Available Due to lack of energy sources in the world, we are obliged to use our current energy sources in the most efficient way. Therefore, in the automotive industry, research works to manufacture more economic cars in terms of fuelconsumption and environmental friendly cars, at the same time satisfying the required performance have been intensively increasing. Some positive results have been obtained by the studies, aimed to change the compression ratio according to the operating conditions of engine. In spark ignition engines in order to improve the combustion efficiency, fuel economy and exhaust emission in the partial loads, the compression ratio must be increased; but, under the high load and low speed conditions to prevent probable knock and hard running compression ratio must be decreased slightly. In this paper, various research works on the variable compression ratio with spark ignition engines, the effects on fuel economy, power output and thermal efficiency have been investigated. According to the results of the experiments performed with engines having variable compression ratio under the partial and mid-load conditions, an increase in engine power, a decrease in fuel consumption, particularly in partial loads up to 30 percent of fuel economy, and also severe reductions of some exhaust emission values were determined.

  20. Characterization of Diesel and Gasoline Compression Ignition Combustion in a Rapid Compression-Expansion Machine using OH* Chemiluminescence Imaging

    Science.gov (United States)

    Krishnan, Sundar Rajan; Srinivasan, Kalyan Kumar; Stegmeir, Matthew

    2015-11-01

    Direct-injection compression ignition combustion of diesel and gasoline were studied in a rapid compression-expansion machine (RCEM) using high-speed OH* chemiluminescence imaging. The RCEM (bore = 84 mm, stroke = 110-250 mm) was used to simulate engine-like operating conditions at the start of fuel injection. The fuels were supplied by a high-pressure fuel cart with an air-over-fuel pressure amplification system capable of providing fuel injection pressures up to 2000 bar. A production diesel fuel injector was modified to provide a single fuel spray for both diesel and gasoline operation. Time-resolved combustion pressure in the RCEM was measured using a Kistler piezoelectric pressure transducer mounted on the cylinder head and the instantaneous piston displacement was measured using an inductive linear displacement sensor (0.05 mm resolution). Time-resolved, line-of-sight OH* chemiluminescence images were obtained using a Phantom V611 CMOS camera (20.9 kHz @ 512 x 512 pixel resolution, ~ 48 μs time resolution) coupled with a short wave pass filter (cut-off ~ 348 nm). The instantaneous OH* distributions, which indicate high temperature flame regions within the combustion chamber, were used to discern the characteristic differences between diesel and gasoline compression ignition combustion. The authors gratefully acknowledge facilities support for the present work from the Energy Institute at Mississippi State University.

  1. Experimental investigation of piston heat transfer under conventional diesel and reactivity-controlled compression ignition combustion regimes

    Energy Technology Data Exchange (ETDEWEB)

    Splitter, Derek A [ORNL; Hendricks, Terry Lee [Sandia National Laboratories (SNL); Ghandhi, Jaal B [University of Wisconsin

    2014-01-01

    The piston of a heavy-duty single-cylinder research engine was instrumented with 11 fast-response surface thermocouples, and a commercial wireless telemetry system was used to transmit the signals from the moving piston. The raw thermocouple data were processed using an inverse heat conduction method that included Tikhonov regularization to recover transient heat flux. By applying symmetry, the data were compiled to provide time-resolved spatial maps of the piston heat flux and surface temperature. A detailed comparison was made between conventional diesel combustion and reactivity-controlled compression ignition combustion operations at matched conditions of load, speed, boost pressure, and combustion phasing. The integrated piston heat transfer was found to be 24% lower, and the mean surface temperature was 25 C lower for reactivity-controlled compression ignition operation as compared to conventional diesel combustion, in spite of the higher peak heat release rate. Lower integrated piston heat transfer for reactivity-controlled compression ignition was found over all the operating conditions tested. The results showed that increasing speed decreased the integrated heat transfer for conventional diesel combustion and reactivity-controlled compression ignition. The effect of the start of injection timing was found to strongly influence conventional diesel combustion heat flux, but had a negligible effect on reactivity-controlled compression ignition heat flux, even in the limit of near top dead center high-reactivity fuel injection timings. These results suggest that the role of the high-reactivity fuel injection does not significantly affect the thermal environment even though it is important for controlling the ignition timing and heat release rate shape. The integrated heat transfer and the dynamic surface heat flux were found to be insensitive to changes in boost pressure for both conventional diesel combustion and reactivity-controlled compression ignition

  2. A University Consortium on Homogeneous Charge Compression Ignition Engine Research

    Energy Technology Data Exchange (ETDEWEB)

    Assanis, Dennis; Atreya, Arvind; Bowman, Craig; Chen, Jyh-Yuan; Cheng, Wai; Davidson, David; Dibble, Robert; Edwards, Chris; Filipi, Zoran; Golden, David; Green, William; Hanson, Ronald; Hedrick, J Karl; Heywood, John; Im, Hong; Lavoie, George; Sick, Volker; Wooldridge, Margaret

    2007-03-31

    Over the course of this four year project, the consortium team members from UM, MIT, Stanford, and Berkeley along with contributors from Sandia National Labs and LLNL, have produced a wide range of results on gasoline HCCI control and implementation. The work spanned a wide range of activities including engine experiments, fundamental chemical kinetics experiments, and an array of analytical modeling techniques and simulations. Throughout the project a collaborative approach has produced a many significant new insights into HCCI engines and their behavior while at the same time we achieved our key consortium goal: to develop workable strategies for gasoline HCCI control and implementation. The major accomplishments in each task are summarized, followed by detailed discussion.

  3. DESIGN OF A HIGH COMPRESSION, DIRECT INJECTION, SPARK-IGNITION, METHANOL FUELED RESEARCH ENGINE WITH AN INTEGRAL INJECTOR-IGNITION SOURCE INSERT, SAE PAPER 2001-01-3651

    Science.gov (United States)

    A stratified charge research engine and test stand were designed and built for this work. The primary goal of this project was to evaluate the feasibility of using a removal integral injector ignition source insert which allows a convenient method of charging the relative locat...

  4. Study of Knocking Effect in Compression Ignition Engine with Hydrogen as a Secondary Fuel

    Directory of Open Access Journals (Sweden)

    R. Sivabalakrishnan

    2014-01-01

    Full Text Available The aim of this project is detecting knock during combustion of biodiesel-hydrogen fuel and also the knock is suppressed by timed injection of diethyl ether (DEE with biodiesel-hydrogen fuel for different loads. Hydrogen fuel is an effective alternate fuel in making a pollution-free environment with higher efficiency. The usage of hydrogen in compression ignition engine leads to production of knocking or detonation because of its lower ignition energy, wider flammability range, and shorter quenching distance. Knocking combustion causes major engine damage, and also reduces the efficiency. The method uses the measurement and analysis of cylinder pressure signal for various loads. The pressure signal is to be converted into frequency domain that shows the accurate knocking combustion of fuel mixtures. The variation of pressure signal is gradually increased and smoothly reduced to minimum during normal combustion. The rapid rise of pressure signal has occurred during knocking combustion. The experimental setup was mainly available for evaluating the feasibility of normal combustion by comparing with the signals from both fuel mixtures in compression ignition engine. This method provides better results in predicting the knocking feature of biodiesel-hydrogen fuel and the usage of DEE provides complete combustion of fuels with higher performance, and lower emission.

  5. LES/FMDF of turbulent jet ignition in a rapid compression machine

    Science.gov (United States)

    Validi, Abdoulahad; Schock, Harold; Toulson, Elisa; Jaberi, Farhad; CFD; Engine Research Labs, Michigan State University Collaboration

    2015-11-01

    Turbulent Jet Ignition (TJI) is an efficient method for initiating and controlling combustion in combustion systems, e.g. internal combustion engines. It enables combustion in ultra-lean mixtures by utilizing hot product turbulent jets emerging from a pre-chamber combustor as the ignition source for the main combustion chamber. Here, we study the TJI-assisted ignition and combustion of lean methane-air mixtures in a Rapid Compression Machine (RCM) for various flow/combustion conditions with the hybrid large eddy simulation/filtered mass density function (LES/FMDF) computational model. In the LES/FMDF model, the filtered form of compressible Navier-Stokes equations are solved with a high-order finite difference scheme for the turbulent velocity, while the FMDF transport equation is solved with a Lagrangian stochastic method to obtain the scalar (species mass fraction and temperature) field. The LES/FMDF data are used to study the physics of TJI and combustion in RCM. The results show the very complex behavior of the reacting flow and the flame structure in the pre-chamber and RCM.

  6. Improving the performance and fuel consumption of dual chamber stratified charge spark ignition engines

    Energy Technology Data Exchange (ETDEWEB)

    Sorenson, S.C.; Pan, S.S.; Bruckbauer, J.J.; Gehrke, G.R.

    1979-09-01

    A combined experimental and theoretical investigation of the nature of the combustion processes in a dual chamber stratified charge spark ignition engine is described. This work concentrated on understanding the mixing process in the main chamber gases. A specially constructed single cylinder engine was used to both conduct experiments to study mixing effects and to obtain experimental data for the validation of the computer model which was constructed in the theoretical portion of the study. The test procedures are described. Studies were conducted on the effect of fuel injection timing on performance and emissions using the combination of orifice size and prechamber to main chamber flow rate ratio which gave the best overall compromise between emissions and performance. In general, fuel injection gave slightly higher oxides of nitrogen, but considerably lower hydrocarbon and carbon monoxide emissions than the carbureted form of the engine. Experiments with engine intake port redesign to promote swirl mixing indicated a substantial increase in the power output from the engine and, that an equivalent power levels, the nitric oxide emissions are approximately 30% lower with swirl in the main chamber than without swirl. The development of a computer simulation of the combustion process showed that a one-dimensional combustion model can be used to accurately predict trends in engine operation conditions and nitric oxide emissions even though the actual flame in the engine is not completely one-dimensional, and that a simple model for mixing of the main chamber and prechamber intake gases at the start of compression proved adequate to explain the effects of swirl, ignition timing, overall fuel air ratio, volumetric efficiency, and variations in prechamber air fuel ratio and fuel rate percentage on engine power and nitric oxide emissions. (LCL)

  7. Fast electron heating of shock compressed solids at high intensities relevant to fast ignition

    International Nuclear Information System (INIS)

    This report describes the experiment entitled 'Fast electron heating of shock compressed solids at high intensities relevant to fast ignition'; carried out at the Central Laser Facility (CLF) from the 5th January to the 15th February 1997. The experiment, funded by the Framework IV Large-Scale Facilities Access Scheme, was proposed by Dr. D. Batani, University of Milan, Italy and carried out by visiting researchers from the University and Ecole Polytechnique, Palaiseau, France. They were supported by UK researchers from the University of Essex, the University of Bristol and the Central Laser Facility, Rutherford Appleton Laboratory. Experimental results: (i) The experiment demonstrated the first results for fast electron deposition in compressed matter. The irradiances used in these experiments are lower than would be used in the fast ignitor scheme but the significance of the results is, nevertheless very relevant to this scheme. (ii) It is shown that in the experiments presented here that ionised, compressed plastic is less effective at stopping the fast electrons than uncompressed, unionised plastic. The stopping power of the compressed material is reduced by a factor of two (in areal density units) over the uncompressed materials. (iii) These experiments are the first measurements of electron stopping power in compressed plasmas but further experiments with more highly compressed plasmas are necessary before the results may be safely extrapolated to fast ignitor conditions. (author)

  8. Effects of In-Cylinder Mixing on Low Octane Gasoline Compression Ignition Combustion

    KAUST Repository

    Badra, Jihad

    2016-04-05

    Gasoline compression ignition (GCI) engines have been considered an attractive alternative to traditional spark ignition engines. Low octane gasoline fuel has been identified as a viable option for the GCI engine applications due to its longer ignition delay characteristics compared to diesel and in the volatility range of gasoline fuels. In this study, we have investigated the effect of different injection timings at part-load conditions using light naphtha stream in single cylinder engine experiments in the GCI combustion mode with injection pressure of 130 bar. A toluene primary reference fuel (TPRF) was used as a surrogate for the light naphtha in the engine simulations performed here. A physical surrogate based on the evaporation characteristics of the light naphtha has been developed and its properties have been implemented in the engine simulations. Full cycle GCI computational fluid dynamics (CFD) engine simulations have been successfully performed while changing the start of injection (SOI) timing from -50° to -11 ° CAD aTDC. The effect of SOI on mixing and combustion phasing was investigated using detailed equivalence ratio-temperature maps and ignition delay times. Both experimental and computational results consistently showed that an SOI of -30° CAD aTDC has the most advanced combustion phasing (CA50), with the highest NOx emission. The effects of the SOI on the fuel containment in the bowl of the piston, the ignition delay time, combustion rate and emissions have been carefully examined through the CFD calculations. It was found that the competition between the equivalence ratio and temperature is the controlling parameter in determining the combustion phasings.

  9. Compression ignition engine having fuel system for non-sooting combustion and method

    Energy Technology Data Exchange (ETDEWEB)

    Bazyn, Timothy; Gehrke, Christopher

    2014-10-28

    A direct injection compression ignition internal combustion engine includes a fuel system having a nozzle extending into a cylinder of the engine and a plurality of spray orifices formed in the nozzle. Each of the spray orifices has an inner diameter dimension of about 0.09 mm or less, and define inter-orifice angles between adjacent spray orifice center axes of about 36.degree. or greater such that spray plumes of injected fuel from each of the spray orifices combust within the cylinder according to a non-sooting lifted flame and gas entrainment combustion pattern. Related methodology is also disclosed.

  10. Possibility to Increase Biofuels Energy Efficiency used for Compression Ignition Engines Fueling

    Directory of Open Access Journals (Sweden)

    Calin D. Iclodean

    2014-02-01

    Full Text Available The paper presents the possibilities of optimizing the use of biofuels in terms of energy efficiency in compression ignition (CI engines fueling. Based on the experimental results was determinate the law of variation of the rate of heat released by the combustion process for diesel fuel and different blends of biodiesel. Using this law, were changed parameters of the engine management system (fuel injection law and was obtain increased engine performance (in terms of energy efficiency for use of different biofuel blends.

  11. Determination of a Vapor Compression Refrigeration System Refrigerant Charge

    Institute of Scientific and Technical Information of China (English)

    YangChun-Xin; DangChao-Bin

    1995-01-01

    A physical model is established in this paper to describe the heat transfer and two phase flow of a refrigerant in the evaporator and condenser of a vapor compression refrigeration system.The model in then used to determine the refrigerant charge in vapor compression units.The model is used for a sensitivity analysis to determine the effect that varing design parameters on the refrigerant charge,The model is also used to evaluate the effect of refrigerant charge and the thermal physical properties on the refrigeration cycle,The predicted value of the refigerant charge and experimental data agree well The model and the method presented in this paper could be used to design vapour compression units such as domestic refrigeratirs and air conditioners.

  12. Advanced charged particle beam ignited nuclear pulse propulsion

    Science.gov (United States)

    Winterberg, F.

    2009-06-01

    It is shown that the mass of the driver for nuclear microexplosion—Orion type—pulse propulsion can be substantially reduced with a special fusion-fast fission configuration, which permits to replace an inefficient laser beam driver with a much more efficient and less massive relativistic electron beam (or light ion beam) driver. The driver mass can be further reduced, and the propulsion efficiency increased, by surrounding the nuclear microexplosion assembly with a shell of conventional hydrogen-rich explosive, helping to ignite the nuclear reaction and dissipating the otherwise lost kinetic neutron energy in the shell which becomes part of the propellant.

  13. Radiochemical determination of Inertial Confinement Fusion capsule compression at the National Ignition Facility

    International Nuclear Information System (INIS)

    We describe a radiochemical measurement of the ratio of isotope concentrations produced in a gold hohlraum surrounding an Inertial Confinement Fusion capsule at the National Ignition Facility (NIF). We relate the ratio of the concentrations of (n,γ) and (n,2n) products in the gold hohlraum matrix to the down-scatter of neutrons in the compressed fuel and, consequently, to the fuel's areal density. The observed ratio of the concentrations of 198m+gAu and 196gAu is a performance signature of ablator areal density and the fuel assembly confinement time. We identify the measurement of nuclear cross sections of astrophysical importance as a potential application of the neutrons generated at the NIF

  14. Radiochemical determination of Inertial Confinement Fusion capsule compression at the National Ignition Facility

    Science.gov (United States)

    Shaughnessy, D. A.; Moody, K. J.; Gharibyan, N.; Grant, P. M.; Gostic, J. M.; Torretto, P. C.; Wooddy, P. T.; Bandong, B. B.; Despotopulos, J. D.; Cerjan, C. J.; Hagmann, C. A.; Caggiano, J. A.; Yeamans, C. B.; Bernstein, L. A.; Schneider, D. H. G.; Henry, E. A.; Fortner, R. J.

    2014-06-01

    We describe a radiochemical measurement of the ratio of isotope concentrations produced in a gold hohlraum surrounding an Inertial Confinement Fusion capsule at the National Ignition Facility (NIF). We relate the ratio of the concentrations of (n,γ) and (n,2n) products in the gold hohlraum matrix to the down-scatter of neutrons in the compressed fuel and, consequently, to the fuel's areal density. The observed ratio of the concentrations of 198m+gAu and 196gAu is a performance signature of ablator areal density and the fuel assembly confinement time. We identify the measurement of nuclear cross sections of astrophysical importance as a potential application of the neutrons generated at the NIF.

  15. COMBUSTION ANALYSIS OF ALGAL OIL METHYL ESTER IN A DIRECT INJECTION COMPRESSION IGNITION ENGINE

    Directory of Open Access Journals (Sweden)

    HARIRAM V.

    2013-02-01

    Full Text Available Algal oil methyl ester was derived from microalgae (Spirulina sp. The microalga was cultivated in BG 11 media composition in a photobioreactor. Upon harvesting, the biomass was filtered and dried. The algal oil was obtained by a two step solvent extraction method using hexane and ether solvent. Cyclohexane was added to biomass to expel the remaining algal oil. By this method 92% of algal oil is obtained. Transesterification process was carried out to produce AOME by adding sodium hydroxide and methanol. The AOME was blended with straight diesel in 5%, 10% and 15% blend ratio. Combustion parameters were analyzed on a Kirloskar single cylinder direct injection compression ignition engine. The cylinder pressure characteristics, the rate of pressure rise, heat release analysis, performance and emissions were studied for straight diesel and the blends of AOME’s. AOME 15% blend exhibits significant variation in cylinder pressure and rate of heat release.

  16. Efficiency and exhaust gas analysis of variable compression ratio spark ignition engine fuelled with alternative fuels

    Directory of Open Access Journals (Sweden)

    N. Seshaiah

    2010-09-01

    Full Text Available Considering energy crises and pollution problems today, investigations have been concentrated on decreasing fuel consumption by using alternative fuels and on lowering the concentration of toxic components in combustion products. In the present work, the variable compression ratio spark ignition engine designed to run on gasoline has been tested with pure gasoline, LPG (Isobutene, and gasoline blended with ethanol 10%, 15%, 25% and 35% by volume. Also, the gasoline mixed with kerosene at 15%, 25% and 35% by volume without any engine modifications has been tested and presented the result. Brake thermal and volumetric efficiency variation with brake load is compared and presented. CO and CO2 emissions have been also compared for all tested fuels.

  17. Radiochemical determination of Inertial Confinement Fusion capsule compression at the National Ignition Facility.

    Science.gov (United States)

    Shaughnessy, D A; Moody, K J; Gharibyan, N; Grant, P M; Gostic, J M; Torretto, P C; Wooddy, P T; Bandong, B B; Despotopulos, J D; Cerjan, C J; Hagmann, C A; Caggiano, J A; Yeamans, C B; Bernstein, L A; Schneider, D H G; Henry, E A; Fortner, R J

    2014-06-01

    We describe a radiochemical measurement of the ratio of isotope concentrations produced in a gold hohlraum surrounding an Inertial Confinement Fusion capsule at the National Ignition Facility (NIF). We relate the ratio of the concentrations of (n,γ) and (n,2n) products in the gold hohlraum matrix to the down-scatter of neutrons in the compressed fuel and, consequently, to the fuel's areal density. The observed ratio of the concentrations of (198m+g)Au and (196g)Au is a performance signature of ablator areal density and the fuel assembly confinement time. We identify the measurement of nuclear cross sections of astrophysical importance as a potential application of the neutrons generated at the NIF. PMID:24985820

  18. Experimental Investigation of Hydrogen Enrichment on Performance and Emission Behaviour of Compression Ignition Engine

    Directory of Open Access Journals (Sweden)

    Gandhi Pullagura

    2012-03-01

    Full Text Available Continuous induction of hydrogen in compression ignition engine offers an advantage of proper mixing with air results in proper combustion. In the present study hydrogen at the constant flow rate of 4 1pm was inducted in the intake, a distance of 40 cm from the intake manifold, along with air. Two different fuels, one i.e.40% blend of used transformer oil (UTO 40 and 60% diesel fuel and the second was neat Used transformer oil (UTO 100 were tested as main fuels in single cylinder, 4-stroke, air cooled direct injection diesel engine developing a power of 4.4 KW, rated speed of 1500 rpm. The performance and emission parameters of the engine were obtained in the investigation and compared with the diesel fuel are presented in this paper

  19. ENVIRONMENTAL ASSESSMENT OF NOX CONTROL ON A COMPRESSION IGNITION LARGE BORE RECIPROCATING INTERNAL COMBUSTION ENGINE. VOLUME 1. TECHNICAL RESULTS

    Science.gov (United States)

    Volume I of the report gives emission results from field tests of the exhaust gas from a large-bore, compression-ignition reciprocating engine burning diesel fuel. An objective of the tests was to evaluate the operating efficiency of the engine with combustion modification NOx co...

  20. ENVIRONMENTAL ASSESSMENT OF NOX CONTROL ON A COMPRESSION IGNITION LARGE BORE RECIPROCATING INTERNAL COMBUSTION ENGINE. VOLUME 2. DATA SUPPLEMENT

    Science.gov (United States)

    Volume II of the report is a compendium of detailed emission and test data from field tests of a large-bore, compression-ignition reciprocating engine burning diesel fuel. The engine was tested during two operating modes: at baseline (normal operation), and with fuel injection re...

  1. 76 FR 25246 - Control of Emissions From New and In-Use Marine Compression-Ignition Engines and Vessels; CFR...

    Science.gov (United States)

    2011-05-04

    ... From the Federal Register Online via the Government Publishing Office ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 1042 Control of Emissions From New and In-Use Marine Compression- Ignition Engines and Vessels; CFR Correction Correction In rule document 2011-8794 appearing on pages 20550-20551 in the...

  2. A spectroscopy study of gasoline partially premixed compression ignition spark assisted combustion

    International Nuclear Information System (INIS)

    Highlights: ► PPC combustion combined with spark assistance and gasoline fuel on a CI engine. ► Chemiluminescence of different chemical species describes the progress of combustion reaction. ► Spectra of a novel combustion mode under SACI conditions is described. ► UV–Visible spectrometry, high speed imaging and pressure diagnostic were employed for analysis. - Abstract: Nowadays many research efforts are focused on the study and development of new combustion modes, mainly based on the use of locally lean air–fuel mixtures. This characteristic, combined with exhaust gas recirculation, provides low combustion temperatures that reduces pollutant formation and increases efficiency. However these combustion concepts have some drawbacks, related to combustion phasing control, which must be overcome. In this way, the use of a spark plug has shown to be a good solution to improve phasing control in combination with lean low temperature combustion. Its performance is well reported on bibliography, however phenomena involving the combustion process are not completely described. The aim of the present work is to develop a detailed description of the spark assisted compression ignition mode by means of application of UV–Visible spectrometry, in order to improve insight on the combustion process. Tests have been performed in an optical engine by means of broadband radiation imaging and emission spectrometry. The engine hardware is typical of a compression ignition passenger car application. Gasoline was used as the fuel due to its low reactivity. Combining broadband luminosity images with pressure-derived heat-release rate and UV–Visible spectra, it was possible to identify different stages of the combustion reaction. After the spark discharge, a first flame kernel appears and starts growing as a premixed flame front, characterized by a low and constant heat-release rate in combination with the presence of remarkable OH radical radiation. Heat release increases

  3. Visualizing fast electron energy transport into laser-compressed high-density fast-ignition targets

    Science.gov (United States)

    Jarrott, L. C.; Wei, M. S.; McGuffey, C.; Solodov, A. A.; Theobald, W.; Qiao, B.; Stoeckl, C.; Betti, R.; Chen, H.; Delettrez, J.; Döppner, T.; Giraldez, E. M.; Glebov, V. Y.; Habara, H.; Iwawaki, T.; Key, M. H.; Luo, R. W.; Marshall, F. J.; McLean, H. S.; Mileham, C.; Patel, P. K.; Santos, J. J.; Sawada, H.; Stephens, R. B.; Yabuuchi, T.; Beg, F. N.

    2016-05-01

    Recent progress in kilojoule-scale high-intensity lasers has opened up new areas of research in radiography, laboratory astrophysics, high-energy-density physics, and fast-ignition (FI) laser fusion. FI requires efficient heating of pre-compressed high-density fuel by an intense relativistic electron beam produced from laser-matter interaction. Understanding the details of electron beam generation and transport is crucial for FI. Here we report on the first visualization of fast electron spatial energy deposition in a laser-compressed cone-in-shell FI target, facilitated by doping the shell with copper and imaging the K-shell radiation. Multi-scale simulations accompanying the experiments clearly show the location of fast electrons and reveal key parameters affecting energy coupling. The approach provides a more direct way to infer energy coupling and guide experimental designs that significantly improve the laser-to-core coupling to 7%. Our findings lay the groundwork for further improving efficiency, with 15% energy coupling predicted in FI experiments using an existing megajoule-scale laser driver.

  4. Detailed Characterization of Particulates Emitted by Pre-Commercial Single-Cylinder Gasoline Compression Ignition Engine

    Energy Technology Data Exchange (ETDEWEB)

    Zelenyuk, Alla; Reitz, Paul; Stewart, Mark L.; Imre, D.; Loeper, Paul; Adams, Cory; Andrie, Michael; Rothamer, David; Foster, David E.; Narayanaswamy, Kushal; Najt, Paul M.; Solomon, Arun S.

    2014-08-01

    Gasoline Compression Ignition (GCI) engines have the potential to achieve high fuel efficiency and to significantly reduce both NOx and particulate matter (PM) emissions by operating under dilute partially-premixed conditions. This low temperature combustion strategy is dependent upon direct-injection of gasoline during the compression stroke and potentially near top dead center (TDC). The timing and duration of the in-cylinder injections can be tailored based on speed and load to create optimized conditions that result in a stable combustion. We present the results of advanced aerosol analysis methods that have been used for detailed real-time characterization of PM emitted from a single-cylinder GCI engine operated at different speed, load, timing, and number and duration of near-TDC fuel injections. PM characterization included 28 measurements of size and composition of individual particles sampled directly from the exhaust and after mass and/or mobility classification. We use these data to calculate particle effective density, fractal dimension, dynamic shape factors in free-molecular and transition flow regimes, average diameter of primary spherules, number of spherules, and void fraction of soot agglomerates.

  5. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter

    International Nuclear Information System (INIS)

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  6. Charged Particle Stopping Power Effects on Ignition: Some Results from an Exact Calculation

    OpenAIRE

    Singleton Jr, Robert L.

    2007-01-01

    A completely rigorous first-principles calculation of the charged particle stopping power has recently been performed by Brown, Preston, and Singleton (BPS). This calculation is exact to leading and next-to-leading order in the plasma number density, including an exact treatment of two-body quantum scattering. The BPS calculation is therefore extremely accurate in the plasma regime realized during the ignition and burn of an inertial confinement fusion capsule. For deuterium-tritium fusion, t...

  7. Analysis of cyclic variations during mode switching between spark ignition and controlled auto-ignition combustion operations

    OpenAIRE

    Chen, T.; Zhao, H; Xie, H.; He, B.

    2014-01-01

    © IMechE 2014. Controlled auto-ignition, also known as homogeneous charge compression ignition, has been the subject of extensive research because of their ability to provide simultaneous reductions in fuel consumption and NOx emissions from a gasoline engine. However, due to its limited operation range, switching between controlled auto-ignition and spark ignition combustion is needed to cover the complete operating range of a gasoline engine for passenger car applications. Previous research...

  8. The Effects of Fuel Stratification and Heat Release Rate Shaping in Reactivity Controlled Compression Ignition (RCCI) Combustion

    Science.gov (United States)

    DelVescovo, Dan A.

    Low temperature combustion strategies have demonstrated high thermal efficiency with low emissions of pollutants, including oxides of nitrogen and particulate matter. One such combustion strategy, called Reactivity Controlled Compression Ignition (RCCI), which involves the port injection of a low reactivity fuel such as gasoline, ethanol, or natural gas, and a direct injection of a high reactivity fuel, such as diesel, has demonstrated excellent control over the heat release event due to the introduction of in-cylinder stratification of equivalence ratio and reactivity. The RCCI strategy is inherently fuel flexible, however the direct injection strategy needs to be tailored to the combination of premixed and direct injected fuels. Experimental results demonstrate that, when comparing different premixed fuels, matching combustion phasing with premixed mass percentage or SOI timing is not sufficient to retain baseline efficiency and emissions results. If the bulk characteristics of the heat release event can be matched, however, then the efficiency and emissions can be maintained. A 0-D methodology for predicting the required fuel stratification for a desired heat release for kinetically-controlled stratified-charge combustion strategies is proposed and validated with 3-D reacting and non-reacting CFD simulations performed with KIVA3Vr2 in this work. Various heat release rate shapes, phasing, duration, and premixed and DI fuel chemistries are explored using this analysis. This methodology provides a means by which the combustion process of a stratified-charge, kinetically-controlled combustion strategy could be optimized for any fuel combination, assuming that the fuel chemistry is well characterized.

  9. Energetic and exergetic analyses of a variable compression ratio spark ignition gas engine

    International Nuclear Information System (INIS)

    Highlights: • Effects of CR and λ on CNG SI ICE 1st and 2nd law analyses are experimentally studied. • The performance of pure methane and a real CNG are observed and compared. • The ratio of actual to Otto cycle thermal efficiencies is 0.78 for all cases. • At least 25.5% of destructed availability is due to combustion irreversibility. • With decrease in methane content, CNG shows more combustion irreversibility. - Abstract: Considering the significance of obtaining higher efficiencies from internal combustion engines (ICE) along with the growing role of natural gas as a fuel, the present work is set to explore the effects of compression ratio (CR hereafter) and air/fuel equivalence ratio (AFER hereafter) on the energy and exergy potentials in a gas-fueled spark ignition internal combustion engine. Experiments are carried out using a single cylinder, port injection, water cooled, variable compression ratio (VCR hereafter), spark ignition engine at a constant engine speed of 2000 rpm. The study involves CRs of 12, 14 and 16 and 10 AFERs between 0.8 and 1.25. Pure methane is utilized for the analysis. In addition, a natural gas blend with the minimum methane content among Iranian gas sources is also tested in order to investigate the effect of real natural gas on findings. The energy analysis involves input fuel power, indicated power and losses due to high temperature of exhaust gases and their unburned content, blow-by and heat loss. The exergy analysis is carried out for availability input and piston, exhaust, and losses availabilities along with destructed entropy. The analysis indicates an increase in the ratio of thermo-mechanical exhaust availability to fuel availability by CR with a maximum near stoichiometry, whereas it is shown that chemical exhaust exergy is not dependent on CR and reduces with AFER. In addition, it is indicated that the ratio of actual cycle to Otto cycle thermal efficiencies is about constant (about 0.784) with changing CR

  10. Charged Particle Stopping Power Effects on Ignition: Some Results from an Exact Calculation

    CERN Document Server

    Singleton, Robert L

    2007-01-01

    A completely rigorous first-principles calculation of the charged particle stopping power has recently been performed by Brown, Preston, and Singleton (BPS). This calculation is exact to leading and next-to-leading order in the plasma number density, including an exact treatment of two-body quantum scattering. The BPS calculation is therefore extremely accurate in the plasma regime realized during the ignition and burn of an inertial confinement fusion capsule. For deuterium-tritium fusion, the 3.5 MeV alpha particle range tends to be 20-30% longer than most models in the literature have predicted, and the energy deposition into the ions tends to be smaller. Preliminary numerical simulations indicate that this increases the rho-R required to achieve ignition.

  11. Characterization and Effect of Using Mahua Oil Biodiesel as Fuel in Compression Ignition Engine

    Institute of Scientific and Technical Information of China (English)

    N.Kapilan; T.P.Ashok Babu; R.P.Reddy

    2009-01-01

    There is an increasing interest in India, to search for suitable alternative fuels that are environment friendly. This led to the choice of Mahua Oil (MO) as one of the main alternative fuels to diesel. In this investigation, Mahua Oil Biodiesel (MOB) and its blend with diesel were used as fuel in a single cylinder, direct injection and com-pression ignition engine. The MOB was prepared from MO by transesterification using methanol and potassium hydroxide. The fuel properties of MOB are close to the diesel and confirm to the ASTM standards. From the en-gine test analysis, it was observed that the MOB, B5 and B20 blend results in lower CO, HC and smoke emis-sions as compared to diesel. But the B5 and B20 blends results in higher efficiency as compared to MOB. Hence MOB or blends of MOB and diesel 035 or B20) can be used as a substitute for diesel in diesel engines used in transportation as well as in the agriculture sector.

  12. Engine performance and emission of compression ignition engine fuelled with emulsified biodiesel-water

    Science.gov (United States)

    Maawa, W. N.; Mamat, R.; Najafi, G.; Majeed Ali, O.; Aziz, A.

    2015-12-01

    The depletion of fossil fuel and environmental pollution has become world crucial issues in current era. Biodiesel-water emulsion is one of many possible approaches to reduce emissions. In this study, emulsified biodiesel with 4%, 6% and 8% of water contents were prepared to be used as fuel in a direct injection compression ignition engine. The performance indicator such as brake power, brake specific fuel consumption (BSFC) and brake thermal efficiency (BTE) and emissions such as NOx and particulate matter (PM) were investigated. The engine was set at constant speed of 2500 rpm and load from 20% to 60%. All the results were compared to B5 (blend of 95% petroleum diesel and 5% palm oil biodiesel) biodiesel. At low load, the BSFC decrease by 12.75% at 4% water ratio and decreased by 1.5% at 6% water ratio. However, the BSFC increases by 17.19% with increasing water ratio to 8% compared to B5. Furthermore, there was no significant decrease in brake power and BTE at 60% load. For 20% and 40% load there was some variance regarding to brake power and BTE. Significant reduction in NOx and PM emissions by 73.87% and 20.00% respectively were achieved with increasing water ratio to 8%. Overall, it is observed that the emulsified of biodiesel-water is an appropriate alternative fuel method to reduce emissions.

  13. Effect of EGR on the exhaust gas temperature and exhaust opacity in compression ignition engines

    Indian Academy of Sciences (India)

    Avinash Kumar Agrawal; Shrawan Kumar Singh; Shailendra Sinha; Mritunjay Kumar Shukla

    2004-06-01

    In diesel engines, NOx formation is a highly temperature-dependent phenomenon and takes place when the temperature in the combustion chamber exceeds 2000 K. Therefore, in order to reduce NOx emissions in the exhaust, it is necessary to keep peak combustion temperatures under control. One simple way of reducing the NOx emission of a diesel engine is by late injection of fuel into the combustion chamber. This technique is effective but increases fuel consumption by 10–15%, which necessitates the use of more effective NOx reduction techniques like exhaust gas recirculation (EGR). Re-circulating part of the exhaust gas helps in reducing NOx, but appreciable particulate emissions are observed at high loads, hence there is a trade-off between NOx and smoke emission. To get maximum benefit from this trade-off, a particulate trap may be used to reduce the amount of unburnt particulates in EGR, which in turn reduce the particulate emission also. An experimental investigation was conducted to observe the effect of exhaust gas re-circulation on the exhaust gas temperatures and exhaust opacity. The experimental setup for the proposed experiments was developed on a two-cylinder, direct injection, air-cooled, compression ignition engine. A matrix of experiments was conducted for observing the effect of different quantities of EGR on exhaust gas temperatures and opacity.

  14. An investigation of the acoustic characteristics of a compression ignition engine operating with biodiesel blends

    International Nuclear Information System (INIS)

    In this paper, an experimental investigation has been carried out on the acoustic characteristics of a compression ignition (CI) engine running with biodiesel blends under steady state operating conditions. The experiment was conducted on a four-cylinder, four-stroke, direct injection and turbocharged diesel engine which runs with biodiesel (B50 and B100) and pure diesel. The signals of acoustic, vibration and in-cylinder pressure were measured during the experiment. To correlate the combustion process and the acoustic characteristics, both phenomena have been investigated. The acoustic analysis resulted in the sound level being increased with increasing of engine loads and speeds as well as the sound characteristics being closely correlated to the combustion process. However, acoustic signals are highly sensitive to the ambient conditions and intrusive background noise. Therefore, the spectral subtraction was employed to minimize the effects of background noise in order to enhance the signal to noise ratio. In addition, the acoustic characteristics of CI engine running with different fuels (biodiesel blends and diesel) was analysed for comparison. The results show that the sound energy level of acoustic signals is slightly higher when the engine fuelled by biodiesel and its blends than that of fuelled by normal diesel. Hence, the acoustic characteristics of the CI engine will have useful information for engine condition monitoring and fuel content estimation.

  15. Study of Effect of Diesel Fuel Energy Rate in Duel Fuel on Performance of Compression Ignition Engine

    OpenAIRE

    Maan Janan Basheer

    2012-01-01

    The aim of this work is to study the effect of diesel fuel percentage on the combustion processes in compression ignition engine using dual fuel (diesel and LPG). The brake thermal efficiency increased with the increase of diesel fuel rate at low loads, and decreased when load increased. To get sufficient operation in engine fueled with dual fuel, it required sufficient flow rate of diesel fuel, if the engine fueled with insufficient diesel fuel erratic operation with miss fire cycles presen...

  16. A Space-Charge-Neutralizing Plasma for Beam Drift Compression

    Energy Technology Data Exchange (ETDEWEB)

    Roy, P.K.; Seidl, P.A.; Anders, A.; Bieniosek, F.M.; Coleman, J.E.; Gilson, E.P.; Greenway, W.; Grote, D.P.; Jung, J.Y.; Leitner, M.; Lidia, S.M.; Logan, B.G.; Sefkow, A.B.; Waldron, W.L.; Welch, D.R.

    2008-08-01

    Simultaneous radial focusing and longitudinal compression of intense ion beams are being studied to heat matter to the warm dense matter, or strongly coupled plasma regime. Higher compression ratios can be achieved if the beam compression takes place in a plasma-filled drift region in which the space-charge forces of the ion beam are neutralized. Recently, a system of four cathodic arc plasma sources has been fabricated and the axial plasma density has been measured. A movable plasma probe array has been developed to measure the radial and axial plasma distribution inside and outside of a {approx} 10 cm long final focus solenoid (FFS). Measured data show that the plasma forms a thin column of diameter {approx} 5 mm along the solenoid axis when the FFS is powered with an 8T field. Measured plasma density of {ge} 1 x 10{sup 13} cm{sup -3} meets the challenge of n{sub p}/Zn{sub b} > 1, where n{sub p} and n{sub b} are the plasma and ion beam density, respectively, and Z is the mean ion charge state of the plasma ions.

  17. Simulation of heating-compressed fast-ignition cores by peta-watt laser-generated electrons

    International Nuclear Information System (INIS)

    In this work, unique particle-in-cell simulations to understand the relativistic electron beam thermalization and subsequent heating of highly compressed plasmas are reported. The simulations yield heated core parameters in good agreement with the GEKKO-PW experimental measurements, given reasonable assumptions of laser-to-electron coupling efficiency and the distribution function of laser-produced electrons. The classical range of the hot electrons exceeds the mass density-core diameter product L by a factor of several. Anomalous stopping appears to be present and is created by the growth and saturation of an electromagnetic filamentation mode that generates a strong back-EMF impeding hot electrons on the injection side of the density maxima. This methodology is then applied to the design of experiments for the ZR machine coupled to the Z-Beamlet/PW laser. Sandia National Laboratories is also developing a combination of experimental and theoretical capabilities useful for the study of pulsed-power-driven fast ignition physics. In preparation for these fast ignition experiments, the theory group at Sandia is modeling various aspects of fast ignition physics. Numerical simulations of laser/plasma interaction, electron transport, and ion generation are being performed using the LSP code. LASNEX simulations of the compression of deuterium/tritium fuel in various reentrant cone geometries are being performed. Analytic and numerical modeling has been performed to determine the conditions required for fast ignition breakeven scaling. These results indicate that to achieve fusion energy output equal to the deposited energy in the core will require about 5% of the laser energy needed for ignition and might be an achievable goal with an upgraded Z-beamlet laser in short pulse mode. (authors)

  18. Hot surface assisted compression ignition in a direct injection natural gas engine

    Energy Technology Data Exchange (ETDEWEB)

    Aesoey, Vilmar

    1996-12-31

    This study investigates the problem of ignition in a direct injection natural gas engine. Due to poor auto-ignition properties of natural gas compared to regular diesel engine fuels, a special arrangement to assist and secure ignition is required. The objective was to investigate the feasibility of using a hot surface as ignition assistance, primarily for application in medium and large size engines, and further study the main mechanisms involved in the ignition process. A constant volume combustion bomb and a test engine are used for experiments, supported by theoretical analysis and numerical simulations. Variable composition of natural gas depending on the gas source and over time, is a important problem causing significant variation in ignition properties. It is shown that even small quantities of non-methane components, which are normally present in natural gases, strongly influence ignition. Actions to handle the ignition problem caused by variable natural composition, are also discussed. In order to estimate the ignition properties of natural gas, a simple correlation to gas composition is proposed, showing good correlation to the experimental data. Mathematical models for simulation of the processes are developed based on fundamental physical relations and experimental results. They are mainly used in this study to support and analyze the physical experiments, but can also be useful in future design and optimization processes. 71 refs., 80 figs., 6 tabs.

  19. Electronic compressibility and charge imbalance relaxation in cuprate superconductors

    OpenAIRE

    Helm, Ch.; Bulaevskii, L. N.; Ryndyk, D. A.; Keller, J.; Rother, S; Koval, Y.; Müller, P.; Kleiner, R.

    2003-01-01

    In the material SmLa$_{1-x}$Sr$_x$CuO$_{4-\\delta}$ with alternating intrinsic Josephson junctions we explain theoretically the relative amplitude of the two plasma peaks in transmission by taking into account the spatial dispersion of the Josephson Plasma Resonance in $c$ direction due to charge coupling. From this and the magnetic field dependence of the plasma peaks in the vortex solid and liquid states it is shown that the electronic compressibility of the CuO$_2$ layers is consistent with...

  20. Radiation hydrodynamics modeling of the highest compression inertial confinement fusion ignition experiment from the National Ignition Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D. S.; Marinak, M. M.; Weber, C. R.; Eder, D. C.; Haan, S. W.; Hammel, B. A.; Hinkel, D. E.; Jones, O. S.; Milovich, J. L.; Patel, P. K.; Robey, H. F.; Salmonson, J. D.; Sepke, S. M.; Thomas, C. A. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2015-02-15

    The recently completed National Ignition Campaign (NIC) on the National Ignition Facility (NIF) showed significant discrepancies between post-shot simulations of implosion performance and experimentally measured performance, particularly in thermonuclear yield. This discrepancy between simulation and observation persisted despite concerted efforts to include all of the known sources of performance degradation within a reasonable two-dimensional (2-D), and even three-dimensional (3-D), simulation model, e.g., using measured surface imperfections and radiation drives adjusted to reproduce observed implosion trajectories [Clark et al., Phys. Plasmas 20, 056318 (2013)]. Since the completion of the NIC, several effects have been identified that could explain these discrepancies and that were omitted in previous simulations. In particular, there is now clear evidence for larger than anticipated long-wavelength radiation drive asymmetries and a larger than expected perturbation seeded by the capsule support tent. This paper describes an updated suite of one-dimensional (1-D), 2-D, and 3-D simulations that include the current best understanding of these effects identified since the NIC, as applied to a specific NIC shot. The relative importance of each effect on the experimental observables is compared. In combination, these effects reduce the simulated-to-measured yield ratio from 125:1 in 1-D to 1.5:1 in 3-D, as compared to 15:1 in the best 2-D simulations published previously. While the agreement with the experimental data remains imperfect, the comparison to the data is significantly improved and suggests that the largest sources for the previous discrepancies between simulation and experiment are now being included.

  1. Radiation hydrodynamics modeling of the highest compression inertial confinement fusion ignition experiment from the National Ignition Campaign

    International Nuclear Information System (INIS)

    The recently completed National Ignition Campaign (NIC) on the National Ignition Facility (NIF) showed significant discrepancies between post-shot simulations of implosion performance and experimentally measured performance, particularly in thermonuclear yield. This discrepancy between simulation and observation persisted despite concerted efforts to include all of the known sources of performance degradation within a reasonable two-dimensional (2-D), and even three-dimensional (3-D), simulation model, e.g., using measured surface imperfections and radiation drives adjusted to reproduce observed implosion trajectories [Clark et al., Phys. Plasmas 20, 056318 (2013)]. Since the completion of the NIC, several effects have been identified that could explain these discrepancies and that were omitted in previous simulations. In particular, there is now clear evidence for larger than anticipated long-wavelength radiation drive asymmetries and a larger than expected perturbation seeded by the capsule support tent. This paper describes an updated suite of one-dimensional (1-D), 2-D, and 3-D simulations that include the current best understanding of these effects identified since the NIC, as applied to a specific NIC shot. The relative importance of each effect on the experimental observables is compared. In combination, these effects reduce the simulated-to-measured yield ratio from 125:1 in 1-D to 1.5:1 in 3-D, as compared to 15:1 in the best 2-D simulations published previously. While the agreement with the experimental data remains imperfect, the comparison to the data is significantly improved and suggests that the largest sources for the previous discrepancies between simulation and experiment are now being included

  2. Applicability of dimethyl ether (DME) in a compression ignition engine as an alternative fuel

    International Nuclear Information System (INIS)

    Highlights: • Overall characteristics of DME fueled engine are reviewed. • Fuel properties characteristics of DME are introduced. • New technologies for DME vehicle are systemically reviewed. • Research trends for the development of DME vehicle in the world are introduced. - Abstract: From the perspectives of environmental conservation and energy security, dimethyl-ether (DME) is an attractive alternative to conventional diesel fuel for compression ignition (CI) engines. This review article deals with the application characteristics of DME in CI engines, including its fuel properties, spray and atomization characteristics, combustion performance, and exhaust emission characteristics. We also discuss the various technological problems associated with its application in actual engine systems and describe the field test results of developed DME-fueled vehicles. Combustion of DME fuel is associated with low NOx, HC, and CO emissions. In addition, PM emission of DME combustion is very low due to its molecular structure. Moreover, DME has superior atomization and vaporization characteristics than conventional diesel. A high exhaust gas recirculation (EGR) rate can be used in a DME engine to reduce NOx emission without any increase in soot emission, because DME combustion is essentially soot-free. To decrease NOx emission, engine after-treatment devices, such as lean NOx traps (LNTs), urea-selective catalytic reduction, and the combination of EGR and catalyst have been applied. To use DME fuel in automotive vehicles, injector design, fuel feed pump, and the high-pressure injection pump have to be modified, combustion system components, including sealing materials, have to be rigorously designed. To use DME fuel in the diesel vehicles, more research is required to enhance its calorific value and engine durability due to the low lubricity of DME, and methods to reduce NOx emission are also required

  3. Electronic compressibility and charge imbalance relaxation in cuprate superconductors

    International Nuclear Information System (INIS)

    In the material SmLa1-xSrxCuO4-δ with alternating intrinsic Josephson junctions we explain theoretically the relative amplitude of the two plasma peaks in transmission by taking into account the spatial dispersion of the Josephson Plasma Resonance in c-direction due to charge coupling. From this and the magnetic field dependence of the plasma peaks in the vortex solid and liquid states it is shown that the electronic compressibility of the CuO2 layers is consistent with a free electron value. Also the London penetration depth λab∼1100 Angst near Tc can be determined. The voltage response in the IV-curve of a Bi2Sr2CaCu2O8 mesa due to microwave irradiation or current injection in a second mesa is related to the nonequilibrium charge imbalance of quasiparticles and Cooper pairs and from our experimental data the relaxation time ∼100 ps is obtained

  4. Fast electron heating of shock compressed solids at high intensities relevant to fast ignition[Hot electrons; Propagation; Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Batani, D.; Bernardinello, A.; Masella, V. [and others

    1998-02-01

    This report describes the experiment entitled 'Fast electron heating of shock compressed solids at high intensities relevant to fast ignition'; carried out at the Central Laser Facility (CLF) from the 5th January to the 15th February 1997. The experiment, funded by the Framework IV Large-Scale Facilities Access Scheme, was proposed by Dr. D. Batani, University of Milan, Italy and carried out by visiting researchers from the University and Ecole Polytechnique, Palaiseau, France. They were supported by UK researchers from the University of Essex, the University of Bristol and the Central Laser Facility, Rutherford Appleton Laboratory. Experimental results: (i) The experiment demonstrated the first results for fast electron deposition in compressed matter. The irradiances used in these experiments are lower than would be used in the fast ignitor scheme but the significance of the results is, nevertheless very relevant to this scheme. (ii) It is shown that in the experiments presented here that ionised, compressed plastic is less effective at stopping the fast electrons than uncompressed, unionised plastic. The stopping power of the compressed material is reduced by a factor of two (in areal density units) over the uncompressed materials. (iii) These experiments are the first measurements of electron stopping power in compressed plasmas but further experiments with more highly compressed plasmas are necessary before the results may be safely extrapolated to fast ignitor conditions. (author)

  5. Effect of Nozzle Design on Fuel Spray and Flame Formation in a High-Speed Compression-Ignition Engine

    Science.gov (United States)

    Rothrock, A M; Waldron, C D

    1937-01-01

    Fuel was injected from different type of injection nozzles into the combustion chamber of the NACA combustion apparatus, operated as a compression-ignition engine. High speed motion pictures were taken of the fuel sprays and combustion. Single-orifice nozzles of 0.008, 0.020, and 0.040 inch diameter, and multiorifice nozzles having 2, 6, and 16 orifices were tested. Nozzles having impinging jets and slit orifices were also included. The photographs indicate that the rate of vapor diffusion from the spray is comparatively slow and that this slow rate of diffusion for combustion chambers with little or no air flow prevents the compression-ignition engine from giving the high performance inherent in the high compression ratios. The sprays from the multiorifice nozzles destroyed the air movement to a greater extent than did those from single orifice nozzles. It is concluded that high performance cannot be realized until the methods of distributing the fuel are improved by means of the injection-nozzle design, air flow, or both.

  6. Self-ignition and oxidation of various hydrocarbons between 600 and 1000 K at high pressure: experimental study with fast compression machine and modeling; Autoinflammation et oxydation de divers hydrocarbures entre 600 et 1000 K a haute pression: etude experimentale en machine a compression rapide et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Ribaucour, M.

    2002-12-01

    Low- and intermediate-temperature oxidation and self-ignition of hydrocarbons play a major role in spark ignition, diesel and HCCI (homogenous charge compression ignition) engines. A deep understanding of the chemistry linked with both phenomena is necessary to improve the engines efficiency and to reduce the formation of pollutants. This document treats of works about the self-ignition and oxidation at high pressure of various hydrocarbons between 600 and 1000 deg. K. The experimental tool used is a fast compression machine fitted with a fast sampling system for the measurement of self-ignition delays and of the concentrations of intermediate oxidation products. The advantages and limitations of this tool are discussed. The self-ignition of various hydrocarbons is compared using pre-defined data which characterize the phenomenologies like cold flames, negative temperature coefficients and self-ignition limits. The hydrocarbons considered are pure or binary mixtures of alkanes, pent-1-ene and n-butyl-benzene. The development of high pressure oxidation reaction schemes of alkanes between 600 and 1000 deg. K is described. It is directly based on the analysis of intermediate oxidation products. This methodology is also applied to pent-1-ene and n-butyl-benzene. The construction of detailed thermo-kinetic models of oxidation and the modeling of phenomena are made for n-butane, n-heptane, for the 3 pentane isomers, for pent-1-ene and n-butyl-benzene. Finally, the perspectives of future works are evoked. They concern new modeling and new methodologies to be applied in more predictive thermo-kinetic models and the reduction of detailed models in order to include them inside fluid dynamics codes. (J.S.)

  7. The effect of additives on properties, performance and emission of biodiesel fuelled compression ignition engine

    International Nuclear Information System (INIS)

    Highlights: • Fuel additives significantly improve the quality of biodiesel and its blends. • Fuel additives used to enhance biodiesel properties. • Fuel saving from optimized vehicle performance and economy with the use of additives. • Emission reduction from fuel system cleanliness and combustion optimization. - Abstract: With growing concern over greenhouse gases there is increasing emphasis on reducing CO2 emissions. Despite engine efficiency improvements plus increased dieselization of the fleet, increasing vehicle numbers results in increasing CO2 emissions. To reserve this trend the fuel source must be changed to renewable fuels which are CO2 neutral. As a renewable, sustainable and alternative fuel for compression ignition engines, biodiesel is widely accepted as comparable fuel to diesel in diesel engines. This is due to several factors like decreasing the dependence on imported petroleum, reducing global warming, increasing lubricity, and reducing substantially the exhaust emissions from diesel engine. However, there is a major disadvantage in the use of biodiesel as it has lower heating value, higher density and higher viscosity, higher fuel consumption and higher NOX emission, which limits its application. Here fuel additives become essential and indispensable tools not only to minimize these drawbacks but also generate specified products to meet the regional and international standards. Fuel additives can contribute towards fuel economy and emission reduction either directly or indirectly. Their use enable vehicle performance to be maintained at, or near, optimum over the lifetime of the vehicle. A variety of additives are used in automotive biodiesel fuel to meet specification limits and to enhance quality. For example, metal based additives, oxygenated additives, antioxidants, cetane number improvers, lubricity improvers and cold flow improvers are used to meet specifications and quality. This article is a literature review of the effect of

  8. Spark ignition engine performance and emissions in a high compression engine using biogas and methane mixtures without knock occurrence

    OpenAIRE

    Gómez Montoya Juan Pablo; Amell Arrieta Andrés A.; Zapata Lopez Jaime F.

    2015-01-01

    With the purpose to use biogas in an internal combustion engine with high compression ratio and in order to get a high output thermal efficiency, this investigation used a diesel engine with a maximum output power 8.5 kW, which was converted to spark ignition mode to use it with gaseous fuels. Three fuels were used: Simulated biogas, biogas enriched with 25% and 50% methane by volume. After conversion, the output power of the engine decreased by 17.64% when...

  9. Addition of RDX/HMX on the Ignition Behaviour of Boron-Potassium Nitrate Pyrotechnic Charge

    Directory of Open Access Journals (Sweden)

    K.R. Rani Krishnan

    2006-07-01

    Full Text Available Boron-potassium nitrate (B-KNO3 (25/75 is a well-known pyrotechnic composition whichfinds application as energy-release system for small-calibre rockets and pyrogen igniters forlarger motors. The decomposition of the oxidiser in this composition is endothermic which canbe activated by the addition of high explosives, which decompose exothermically. This paperdescribes the influence of two nitramine explosives, RDX and HMX, on the ignition characteristicsof B-KNO3 composition using thermogravimetry, differential scanning calorimetry, heat andpressure output measurements. Different compositions were prepared by varying the amount ofRDX/HMX from 10 per cent to 50 per cent. Thermal studies on the B-KNO3/high explosivemixtures reveal that these undergo two-stage decomposition. The first stage corresponds to thedecomposition of high explosive and the second stage corresponds to that of the reaction betweenB and KNO3. Kinetic parameters were calculated for both the stages of TG curves using Coats-Redfern and Mac Callum-Tanner methods. Ignition temperature of B-KNO3 decreases on theaddition of RDX/HMX while the onset of RDX or HMX decomposition is not significantly affectedby B-KNO3. The pressure output of B-KNO3 increases on adding RDX/HMX. The heat outputof B-KNO3 is not much affected by the addition of RDX or HMX, even though the heat ofexplosion of RDX and HMX are low. This is due to the reaction between the combustion productsof RDX/HMX and reaction products of B-KNO3 to form more exothermic products like B2O3,releasing extra heat. The flame temperature of the charge increases while the average molecularweight of the products of combustion decreases as the RDX/HMX content increases. Thus, thecharge, on addition of RDX or HMX, produces higher pressure output, maintaining the heatoutput at comparable levels.

  10. 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.

  11. Impact of Biodiesel Blends and Di-Ethyl-Ether on the Cold Starting Performance of a Compression Ignition Engine

    Directory of Open Access Journals (Sweden)

    Adrian Clenci

    2016-04-01

    Full Text Available The use of biodiesel fuel in compression ignition engines has the potential to reduce CO2, which can lead to a reduction in global warming and environmental hazards. Biodiesel is an attractive fuel, as it is made from renewable resources. Many studies have been conducted to assess the impact of biodiesel use on engine performances. Most of them were carried out in positive temperature conditions. A major drawback associated with the use of biodiesel, however, is its poor cold flow properties, which have a direct influence on the cold starting performance of the engine. Since diesel engine behavior at negative temperatures is an important quality criterion of the engine’s operation, one goal of this paper is to assess the starting performance at −20 °C of a common automotive compression ignition engine, fueled with different blends of fossil diesel fuel and biodiesel. Results showed that increasing the biodiesel blend ratio generated a great deterioration in engine startability. Another goal of this study was to determine the biodiesel blend ratio limit at which the engine would not start at −20 °C and, subsequently, to investigate the impact of Di-Ethyl-Ether (DEE injection into the intake duct on the engine’s startability, which was found to be recovered.

  12. Thermodynamic analysis and comparison of downdraft gasifiers integrated with gas turbine, spark and compression ignition engines for distributed power generation

    International Nuclear Information System (INIS)

    The objective of the present article is to assess and compare the performance of electricity generation systems integrated with downdraft biomass gasifiers for distributed power generation. A model for estimating the electric power generation of internal combustion engines and gas turbines powered by syngas was developed. First, the model determines the syngas composition and the lower heating value; and second, these data are used to evaluate power generation in Otto, Diesel, and Brayton cycles. Four synthesis gas compositions were tested for gasification with: air; pure oxygen; 60% oxygen with 40% steam; and 60% air with 40% steam. The results show a maximum power ratio of 0.567 kWh/Nm3 for the gas turbine system, 0.647 kWh/Nm3 for the compression ignition engine, and 0.775 kWh/Nm3 for the spark-ignition engine while running on synthesis gas which was produced using pure oxygen as gasification agent. When these three systems run on synthesis gas produced using atmospheric air as gasification agent, the maximum power ratios were 0.274 kWh/Nm3 for the gas turbine system, 0.302 kWh/Nm3 for CIE, and 0.282 kWh/Nm3 for SIE. The relationship between power output and synthesis gas flow variations is presented as is the dependence of efficiency on compression ratios. Since the maximum attainable power ratio of CIE is higher than that of SIE for gasification with air, more research should be performed on utilization of synthesis gas in CIE. - Highlights: •Engines and gas turbines integrated with gasification were compared. •Four different gasification agents were considered in the analysis. •It was found that a syngas–air mixture has to be considered in the compression. •Good accuracy with respect to available experimental data. •For air gasification higher power ratio was found for compression ignition engines

  13. 49 CFR 173.303 - Charging of cylinders with compressed gas in solution (acetylene).

    Science.gov (United States)

    2010-10-01

    ... Federal Register citations affecting § 173.303, see the List of CFR Sections Affected which appears in the... 49 Transportation 2 2010-10-01 2010-10-01 false Charging of cylinders with compressed gas in....303 Charging of cylinders with compressed gas in solution (acetylene). (a) Cylinder, filler...

  14. Numerical and experimental characterization of knock occurrence in a turbo-charged spark-ignition engine

    International Nuclear Information System (INIS)

    Highlights: • An index of knock intensity has been based on the cylinder pressure oscillations. • This index allows to set the knock limited spark at different engine operating points. • The influence of the transducer position on the measurement of the pressure oscillations is investigated. - Abstract: In this paper, knock intensity is deeply studied through experimental tests carried out on a turbo-charged spark-ignition engine. The experimental methodology is based on the analysis of the pressure signals detected within the engine combustion chamber. In order to evaluate knock intensity, fast Fourier transform (FFT) and bandpass filtering techniques have been used to process the cylinder pressure values acquired in five hundred consecutive cycles. Resonance frequencies have been found at about 8.0 kHz, 13.5 kHz and 18.5 kHz. The maximum amplitude of pressure oscillations (MAPO) has been calculated for every engine cycle. In order to discriminate between knocking cycles and free knock cycles, MAPO values are compared to threshold values. These values have been determined following a statistical approach described in the paper. An index of knock intensity, that takes into account both the extent of knocking events and the cycle- to-cycle variation has been introduced. Thus, at different engine operating points, the knock limited spark advance can be found. At the end, a numerical analysis of the combustion process has been carried out in order to find a relationship between the knock occurrence and the combustion chamber geometry. A 3-D computational model, based on AVL FIRE v2011 code, has been utilized. The 3-D model is able to predict the auto-ignition zones. By matching these zones and the map of mixture distribution, it is possible to predict the location of the most dangerous areas within the combustion chamber. Furthermore, comparisons of calculated and measured data provide sound information about the importance of pressure transducer position in

  15. Diesel-alcohol-castor oil fuel blend as an alternative fuel for compression ignition motors; Misturas diesel-alcool-oleo de ricina como um combustivel alternativo para motores de ignicao por compressao

    Energy Technology Data Exchange (ETDEWEB)

    Peralta, Eduardo Gagliuffi; Bastos, Jose Guilherme R.R.; Barbosa, Cleiton Rubens Formiga [Rio Grande do Norte Univ., Natal, RN (Brazil). Centro de Tecnologia. Dept. de Engenharia Mecanica]. E-mail: eduardo@dem.ufrn.br

    2000-07-01

    This work evaluates some characteristics of the diesel-alcohol-castor oil ternary blends, where the castor oil is used as co-solvent viewing the using in compression ignition motors. The obtained results present the possibility of using those ternary blends as alternative fuels in compression ignition motors to be adopted in regions where the blend components are available.

  16. The Effect of Compression Ratio, Fuel Octane Rating, and Ethanol Content on Spark-Ignition Engine Efficiency.

    Science.gov (United States)

    Leone, Thomas G; Anderson, James E; Davis, Richard S; Iqbal, Asim; Reese, Ronald A; Shelby, Michael H; Studzinski, William M

    2015-09-15

    Light-duty vehicles (LDVs) in the United States and elsewhere are required to meet increasingly challenging regulations on fuel economy and greenhouse gas (GHG) emissions as well as criteria pollutant emissions. New vehicle trends to improve efficiency include higher compression ratio, downsizing, turbocharging, downspeeding, and hybridization, each involving greater operation of spark-ignited (SI) engines under higher-load, knock-limited conditions. Higher octane ratings for regular-grade gasoline (with greater knock resistance) are an enabler for these technologies. This literature review discusses both fuel and engine factors affecting knock resistance and their contribution to higher engine efficiency and lower tailpipe CO2 emissions. Increasing compression ratios for future SI engines would be the primary response to a significant increase in fuel octane ratings. Existing LDVs would see more advanced spark timing and more efficient combustion phasing. Higher ethanol content is one available option for increasing the octane ratings of gasoline and would provide additional engine efficiency benefits for part and full load operation. An empirical calculation method is provided that allows estimation of expected vehicle efficiency, volumetric fuel economy, and CO2 emission benefits for future LDVs through higher compression ratios for different assumptions on fuel properties and engine types. Accurate "tank-to-wheel" estimates of this type are necessary for "well-to-wheel" analyses of increased gasoline octane ratings in the context of light duty vehicle transportation. PMID:26237538

  17. Performance and emission characteristics of a DI compression ignition engine operated on Honge, Jatropha and sesame oil methyl esters

    Energy Technology Data Exchange (ETDEWEB)

    Banapurmath, N.R.; Tewari, P.G. [Department of Mechanical Engineering, B.V.B. College of Engineering and Technology, Vidyanagar, Poona-Bangalore Road, Hubli 580031 (India); Hosmath, R.S. [Department of Mechanical Engineering, K.L.E' s C.E.T., Belgaum (India)

    2008-09-15

    The high viscosity of vegetable oils leads to problem in pumping and spray characteristics. The inefficient mixing of vegetable oils with air contributes to incomplete combustion. The best way to use vegetable oils as fuel in compression ignition (CI) engines is to convert it into biodiesel. Biodiesel is a methyl or ethyl ester of fatty acids made from vegetable oils (both edible and non-edible) and animal fat. The main resources for biodiesel production can be non-edible oils obtained from plant species such as Pongamia pinnata (Honge oil), Jatropha curcas (Ratanjyot), Hevea brasiliensis (Rubber) and Calophyllum inophyllum (Nagchampa). Biodiesel can be used in its pure form or can be blended with diesel to form different blends. It can be used in CI engines with very little or no engine modifications. This is because it has properties similar to mineral diesel. This paper presents the results of investigations carried out on a single-cylinder, four-stroke, direct-injection, CI engine operated with methyl esters of Honge oil, Jatropha oil and sesame oil. Comparative measures of brake thermal efficiency, smoke opacity, HC, CO, NO{sub X}, ignition delay, combustion duration and heat release rates have been presented and discussed. Engine performance in terms of higher brake thermal efficiency and lower emissions (HC, CO, NO{sub X}) with sesame oil methyl ester operation was observed compared to methyl esters of Honge and Jatropha oil operation. (author)

  18. Time-resolved compression of a capsule with a cone to high density for fast-ignition laser fusion

    Science.gov (United States)

    Theobald, W.; Solodov, A. A.; Stoeckl, C.; Anderson, K. S.; Beg, F. N.; Epstein, R.; Fiksel, G.; Giraldez, E. M.; Glebov, V. Yu.; Habara, H.; Ivancic, S.; Jarrott, L. C.; Marshall, F. J.; McKiernan, G.; McLean, H. S.; Mileham, C.; Nilson, P. M.; Patel, P. K.; Pérez, F.; Sangster, T. C.; Santos, J. J.; Sawada, H.; Shvydky, A.; Stephens, R. B.; Wei, M. S.

    2014-12-01

    The advent of high-intensity lasers enables us to recreate and study the behaviour of matter under the extreme densities and pressures that exist in many astrophysical objects. It may also enable us to develop a power source based on laser-driven nuclear fusion. Achieving such conditions usually requires a target that is highly uniform and spherically symmetric. Here we show that it is possible to generate high densities in a so-called fast-ignition target that consists of a thin shell whose spherical symmetry is interrupted by the inclusion of a metal cone. Using picosecond-time-resolved X-ray radiography, we show that we can achieve areal densities in excess of 300 mg cm-2 with a nanosecond-duration compression pulse—the highest areal density ever reported for a cone-in-shell target. Such densities are high enough to stop MeV electrons, which is necessary for igniting the fuel with a subsequent picosecond pulse focused into the resulting plasma.

  19. Time-resolved compression of a capsule with a cone to high density for fast-ignition laser fusion

    International Nuclear Information System (INIS)

    The advent of high-intensity lasers enables us to recreate and study the behaviour of matter under the extreme densities and pressures that exist in many astrophysical objects. It may also enable us to develop a power source based on laser-driven nuclear fusion. Achieving such conditions usually requires a target that is highly uniform and spherically symmetric. Here we show that it is possible to generate high densities in a so-called fast-ignition target that consists of a thin shell whose spherical symmetry is interrupted by the inclusion of a metal cone. Using picosecond-time-resolved X-ray radiography, we show that we can achieve areal densities in excess of 300 mg cm-2 with a nanosecond-duration compression pulse -- the highest areal density ever reported for a cone-in-shell target. Such densities are high enough to stop MeV electrons, which is necessary for igniting the fuel with a subsequent picosecond pulse focused into the resulting plasma

  20. Burn control of an ignited Cat-D tokamak by compression-decompression and fuel injection

    International Nuclear Information System (INIS)

    The possibility of eliminating the thermal instability by applications of major-radius compression-decompression and fueling rate regulation has been studied, with the calculations based on non-linear simulation. The plasma can be stabilized by simultaneous applications of these control methods in most of the range of field decay index m considered, i.e. -1.5 ≤ m ≤ 1.5. The stabilization is not obtained if either compression-decompression or fueling rate regulation is separately applied. An exception exists when m ∼ 0.8; in this case it is possible to suppress the thermal instability by compression-decompression alone. (author)

  1. Study of Effect of Diesel Fuel Energy Rate in Duel Fuel on Performance of Compression Ignition Engine

    Directory of Open Access Journals (Sweden)

    Maan Janan Basheer

    2012-01-01

    Full Text Available The aim of this work is to study the effect of diesel fuel percentage on the combustion processes in compression ignition engine using dual – fuel (diesel and LPG. The brake thermal efficiency increased with the increase of diesel fuel rate at low loads, and decreased when load increased. To get sufficient operation in engine fueled with dual fuel, it required sufficient flow rate of diesel fuel, if the engine fueled with insufficient diesel fuel erratic operation with miss fire cycles presented.Dual-fuel operation at part load showed higher specific fuel consumption than straight diesl operation. At full loads, brake specific fuel consumption of duel fuel engine approaches that for diesel fuel values.

  2. Burn control of an ignited D-T tokamak by compression-decompression and fuel injection

    International Nuclear Information System (INIS)

    The possibility of eliminating the thermal instability by applications of major radius compression-decompression and fueling rate regulation has been studied, with calculations based on non-linear simulation. The plasma density change during operation has been taken into account. It is difficult to suppress the thermal instability when either compression-decompression or fueling rate regulation is separately applied. But the plasma can be stabilized by simultaneous applications of these control methods even when the particle recycling is stopped. (author)

  3. PERFORMANCE, COMBUSTION AND EMISSION CHARACTERISTICS OF COMPRESSION IGNITION ENGINE USING NANO - FUEL: A REVIEW

    Directory of Open Access Journals (Sweden)

    Gurinder Singh

    2015-06-01

    Full Text Available The limited fossil fuel resources along with the need to reduce emissions are major impulse to the development of sustainable, renewable and alternative fuel instead of diesel in CI engine. The main objective of this paper is to study the performance and emission characteristics of CI engine using biodie sel with additives as alternative fuel. Biodiesel have not shown significantly improvement in performance, but shown decreasing trend in emission parameters, especially in Sox, CO and CO2 except to NOx. Nanoparticle added fuel improves the emissions and pe rformance of CI engine due to the positive effect of nanofuels on the fuel properties and ignition delay.

  4. A study of diesel-hydrogen fuel exhaust emissions in a compression ignition engine/generator assembly

    International Nuclear Information System (INIS)

    A compression engine and duel-fuel supply system was studied in order to determine the influence of hydrogen gas on a diesel engine's exhaust system. Commercially available solenoid valves and pulse actuators were used in a customized mechatronic control unit (MICU) to inject the hydrogen gas into the cylinders during the experiments. The MICU was designed as a generic external attachment. Diesel fuel was used to ignite the hydrogen gas-air mixture after compression. Various different electrical loads were then applied using an alternator in order to stimulate the engine governor and control diesel flow. Results of the study showed that measured carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxide (NOx) loads of exhaust emissions increased, while emissions of carbon dioxide (CO2) decreased. Results also showed that higher temperatures and levels of NOx occurred when hydrogen was mixed with the induced air. It was concluded that higher levels of hydrogen may be needed to reduce emissions. 17 refs., 5 tabs., 2 figs

  5. Spark ignition engine performance and emissions in a high compression engine using biogas and methane mixtures without knock occurrence

    Directory of Open Access Journals (Sweden)

    Gómez Montoya Juan Pablo

    2015-01-01

    Full Text Available With the purpose to use biogas in an internal combustion engine with high compression ratio and in order to get a high output thermal efficiency, this investigation used a diesel engine with a maximum output power 8.5 kW, which was converted to spark ignition mode to use it with gaseous fuels. Three fuels were used: Simulated biogas, biogas enriched with 25% and 50% methane by volume. After conversion, the output power of the engine decreased by 17.64% when using only biogas, where 7 kW was the new maximum output power of the engine. The compression ratio was kept at 15.5:1, and knocking did not occur during engine operation. Output thermal efficiency operating the engine in SI mode with biogas enriched with 50% methane was almost the same compared with the engine running in diesel-biogas dual mode at full load and was greater at part loads. The dependence of the diesel pilot was eliminated when biogas was used in the engine converted in SI mode. The optimum condition of experiment for the engine without knocking was using biogas enriched with 50% methane, with 12 degrees of spark timing advance and equivalence ratio of 0.95, larger output powers and higher values of methane concentration lead the engine to knock operation. The presence of CO2 allows operating engines at high compression ratios with normal combustion conditions. Emissions of nitrogen oxides, carbon monoxide and unburnt methane all in g/kWh decreased when the biogas was enriched with 50% methane.

  6. Moteurs composites à allumage par compression et cycle de Rankine Dual Fuel Compression Ignition Engines Operating on the Rankine Cycle

    Directory of Open Access Journals (Sweden)

    Daugas C.

    2006-11-01

    Full Text Available Sur les 60 % de l'énergie introduite dans un groupe électrogène et perdue sous forme de chaleur, une bonne partie peut être utilisée pour fabriquer à nouveau de l'électricité à partir d'une turbine à vapeur. Les moteurs dual fuel brûlant essentiellement du gaz naturel sont remarquablement placés pour une telle récupération, dont le rendement est meilleur aux charges partielles que celui des moteurs diesel classiques. Les différents types de fluides utilisés pour la récupération sont examinés : avantages des fluides organiques sur l'eau. Études d'une réalisation concrète. Fonctionnement aux charges partielles. Influence des différents paramètres pour obtenir le meilleur rapport prix/puissance. Of the 60% of input energy lost in the form of heat in a generating set, a sizeable part can be used to generate electricity again by means of a steam turbine. Dual fuel engines which mainly burn natural gas are outstandingly suitable for such a recovery process, the efficiency under partial loads being better than that of conventional diesel engines. The author considers the different types of fluids used for the recovery process superiority of organic fluids over water. Study of a concrete example. Operation with partial loads. Influence of the different parameters in the quest for the best cost-power ratio.

  7. THE EFFECT OF VARIABLE COMPRESSION RATIO ON FUEL CONSUMPTION IN SPARK IGNITION ENGINES

    OpenAIRE

    Yakup SEKMEN; ERDURANLI, Perihan; AKBAŞ, Ali; SALMAN, M. Sahir

    2002-01-01

    Due to lack of energy sources in the world, we are obliged to use our current energy sources in the most efficient way. Therefore, in the automotive industry, research works to manufacture more economic cars in terms of fuelconsumption and environmental friendly cars, at the same time satisfying the required performance have been intensively increasing. Some positive results have been obtained by the studies, aimed to change the compression ratio according to the operating conditions of engin...

  8. Addition of RDX/HMX on the Ignition Behaviour of Boron-Potassium Nitrate Pyrotechnic Charge

    OpenAIRE

    K.R. Rani Krishnan; R. Anandavally Ammal; B. Hariharanath; A. G. Rajendran; C. B. Kartha

    2006-01-01

    Boron-potassium nitrate (B-KNO3) (25/75) is a well-known pyrotechnic composition whichfinds application as energy-release system for small-calibre rockets and pyrogen igniters forlarger motors. The decomposition of the oxidiser in this composition is endothermic which canbe activated by the addition of high explosives, which decompose exothermically. This paperdescribes the influence of two nitramine explosives, RDX and HMX, on the ignition characteristicsof B-KNO3 composition using thermogra...

  9. Taking into care metastatic medullary compressions; Prise en charge des compressions medullaires metastatiques

    Energy Technology Data Exchange (ETDEWEB)

    Dupin, C.; Feuvret, L. [Groupe hospitalier Pitie-Salpetriere, 75 - Paris (France)

    2010-10-15

    As between 5 and 14 per cent of patients suffering from cancer will suffer from a metastatic medullary compression which severely impacts the vital and functional prognostic, the authors proposes an overview of the different techniques used to take these compressions into care: surgery, radiotherapy and cortico-therapy. They describe their positive and negative impacts. Short communication

  10. Survey of Greener Ignition and Combustion Systems for Internal Combustion Engines

    OpenAIRE

    Luo, Wuqiao; Li, Yun; Tian, Zhong; Gao, Bo; Tong, Ling; Wang, Houjun; Zeng, Baoqing

    2015-01-01

    The spark and compression ignition principles of, petrol and diesel internal combustion engines (ICEs) have, not advanced for a century. These do not lead to complete, combustion and hence result in high exhaust emission and, low energy efficiency. This paper presents a comprehensive survey on the attempts and developments of greener ignition, and combustion systems for ICEs and points out that, homogeneous charge microwave ignition (HCMI) holds the, key to a perfect solution. Increasing the ...

  11. Performance and Emission analysis of Compression Ignition engine in Dual fuel mode using Rice bran biodiesel and LPG

    Directory of Open Access Journals (Sweden)

    Hariram Venkatesan

    2016-07-01

    Full Text Available In the modern world, pollution levels are increasing to a great extent mainly due to vehicular emissions which drives the industries towards finding alternative fuel sources like Hydrogen, CNG, LPG, Vegetable oil and many more. In the present study, Rice bran biodiesel was used along with liquefied petroleum gas in the dual fuel mode in a single cylinder, air cooled compression ignition engine and its performance and emission characteristics were studied. Rice bran ethyl ester was derived using ethanol and sodium hydroxide through Transesterification process. 7.5 mg/cycle of rice bran ethyl ester was injected with liquefied petroleum gas as pilot fuel. The experimental investigation revealed that the brake thermal efficiency was found to be comparatively better than straight diesel. The brake specific energy consumption was noticed to be lower for dual fuel mode than straight diesel mainly at part load operations. The CO and UBHC emissions was found to be reducing with an increase in NOx at high loading condition due to better combustion.

  12. Evidence of multi-petapascal pressures in converging shock compression of deutero-polyethene at the National Ignition Facility

    Science.gov (United States)

    Bachmann, B.-L.; Nilsen, J.; Kritcher, A. L.; Doeppner, T.; Swift, D. C.; Collins, G. W.; Glenzer, S.; Kraus, D.; Falcone, R. W.

    2015-06-01

    A converging shock was induced in a sphere of deuterated polyethene using a hohlraum x-ray drive at the National Ignition Facility. A CH ablator was deposited over the sample, including a Ge-doped radiographic marker layer near its inner edge. Density and opacity profiles were deduced from streaked x-ray radiography, giving a measurement of the shock Hugoniot from 10-80 TPa. As the shock reached the center of the sample, intense x-rays and neutrons were produced, detected with x-ray cameras and neutron scintillators respectively. Penumbral imaging of the x-ray flash showed that shock convergence was spherical to 20 percent or better. The neutron time-of-flight record showed a well-resolved D-D peak, and also a lower D-T peak from tritons produced in the D-D reactions. The x-ray and neutron signals were in very encouraging agreement with radiation hydrodynamics simulations. Analysis of the peak shapes and comparison with the simulations indicates that reaction-averaged temperatures in the hotspot were in the kilovolt range with pressures of several petapascals (tens of gigabars). The hotspot can provide valuable insight on the limits of shock compression before transport perturbs the state ahead. Performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  13. Performance and Emission Characteristics of a Compression Ignition Engine Operating on Blends of Castor Oil Biodiesel-Diesel

    Science.gov (United States)

    Kanwar, Roopesh; Sharma, Pushpendra Kumar; Singh, Aditya Narayan; Agrawal, Yadvendra Kumar

    2016-06-01

    Diesel vehicles are the nerves and veins of transportation, particularly in developing countries. With the rapid rate of modernization, increasing demand of fuel is inevitable. The exponential increase in fuel prices and the scarcity of its supply from the environment have promoted interest in the development of alternative sources of fuel. In this work, genus Ricinus communis L. was studied in order to delimit their potential as a raw material for biodiesel production. Further, castor oil, ethyl ester were prepared by transesterification using potassium hydroxide (KOH) as a catalyst and tested on a four-stroke, single-cylinder compression ignition engine. The test was carried out at a constant speed of 3000 rpm at different loads. The results represent a substantial decrease in carbon monoxide (CO) emission with an increasing biodiesel percentage. The reduction of CO in B05, B10, B15 and B20 averaged 11.75, 22.02, 24.23 and 28.79 %, respectively, compared to mineral diesel. The emission results of the comparative test indicated that CO, oxygen (O2) and smoke density emissions are found to be lower when the engine is filled with B05, B10, B15 and B20 as compared to mineral diesel, while carbon dioxide (CO2) and nitrogen oxide (NOx) with B05, B10, B15 and B20 are found to increase marginally. Brake thermal efficiency and brake specific fuel consumption decrease and increase respectively in biodiesel with different blends in comparison of mineral diesel.

  14. Off-road compression-ignition engine emission regulations under the Canadian Environmental Protection Act 1999 : guidance document

    International Nuclear Information System (INIS)

    This guide explained the requirements for Off-Road Compression Ignition Engine Emission Regulations established under the Canadian Environmental Protection Act. The regulations are enforced by Environment Canada, which authorizes and monitors the use of the national emissions mark. The regulations prescribe standards for off-road engines that operate as reciprocating, internal combustion engines, other than those that operate under characteristics similar to the Otto combustion cycle and that use a spark plug or other sparking device. The regulations apply to engines that are typically diesel-fuelled and found in construction, mining, farming and forestry machines such as tractors, excavators and log skidders. Four different types of persons are potentially affected by the regulations: Canadian engine manufacturers; distributors of Canadian engines or machines containing Canadian engines; importers of engines or machines for the purpose of sale; and persons not in companies importing engines or machines. Details of emission standards were presented, as well as issues concerning evidence of conformity, importing engines, and special engine cases. Compliance and enforcement details were reviewed, as well as applicable standards and provisions for emission control systems and defeat devices; exhaust emissions; crankcase and smoke emissions; and adjustable parameters. Details of import declarations were reviewed, as well as issues concerning defects and maintenance instructions. 4 tabs., 4 figs

  15. Application of multicriteria decision making methods to compression ignition engine efficiency and gaseous, particulate, and greenhouse gas emissions.

    Science.gov (United States)

    Surawski, Nicholas C; Miljevic, Branka; Bodisco, Timothy A; Brown, Richard J; Ristovski, Zoran D; Ayoko, Godwin A

    2013-02-19

    Compression ignition (CI) engine design is subject to many constraints, which present a multicriteria optimization problem that the engine researcher must solve. In particular, the modern CI engine must not only be efficient but must also deliver low gaseous, particulate, and life cycle greenhouse gas emissions so that its impact on urban air quality, human health, and global warming is minimized. Consequently, this study undertakes a multicriteria analysis, which seeks to identify alternative fuels, injection technologies, and combustion strategies that could potentially satisfy these CI engine design constraints. Three data sets are analyzed with the Preference Ranking Organization Method for Enrichment Evaluations and Geometrical Analysis for Interactive Aid (PROMETHEE-GAIA) algorithm to explore the impact of (1) an ethanol fumigation system, (2) alternative fuels (20% biodiesel and synthetic diesel) and alternative injection technologies (mechanical direct injection and common rail injection), and (3) various biodiesel fuels made from 3 feedstocks (i.e., soy, tallow, and canola) tested at several blend percentages (20-100%) on the resulting emissions and efficiency profile of the various test engines. The results show that moderate ethanol substitutions (~20% by energy) at moderate load, high percentage soy blends (60-100%), and alternative fuels (biodiesel and synthetic diesel) provide an efficiency and emissions profile that yields the most "preferred" solutions to this multicriteria engine design problem. Further research is, however, required to reduce reactive oxygen species (ROS) emissions with alternative fuels and to deliver technologies that do not significantly reduce the median diameter of particle emissions. PMID:23343018

  16. Combustion and exhaust emission characteristics of a dual fuel compression ignition engine operated with pilot Diesel fuel and natural gas

    International Nuclear Information System (INIS)

    Towards the effort of reducing pollutant emissions, especially soot and nitrogen oxides, from direct injection Diesel engines, engineers have proposed various solutions, one of which is the use of a gaseous fuel as a partial supplement for liquid Diesel fuel. These engines are known as dual fuel combustion engines, i.e. they use conventional Diesel fuel and a gaseous fuel as well. This technology is currently reintroduced, associated with efforts to overcome various difficulties of HCCI engines, using various fuels. The use of natural gas as an alternative fuel is a promising solution. The potential benefits of using natural gas in Diesel engines are both economical and environmental. The high autoignition temperature of natural gas is a serious advantage since the compression ratio of conventional Diesel engines can be maintained. The present contribution describes an experimental investigation conducted on a single cylinder DI Diesel engine, which has been properly modified to operate under dual fuel conditions. The primary amount of fuel is the gaseous one, which is ignited by a pilot Diesel liquid injection. Comparative results are given for various engine speeds and loads for conventional Diesel and dual fuel operation, revealing the effect of dual fuel combustion on engine performance and exhaust emissions

  17. Combustion and exhaust emission characteristics of a compression ignition engine using liquefied petroleum gas-Diesel blended fuel

    International Nuclear Information System (INIS)

    Towards the effort of reducing pollutant emissions, especially smoke and nitrogen oxides, from direct injection (DI) Diesel engines, engineers have proposed various solutions, one of which is the use of a gaseous fuel as a partial supplement for liquid Diesel fuel. The use of liquefied petroleum gas (LPG) as an alternative fuel is a promising solution. The potential benefits of using LPG in Diesel engines are both economical and environmental. The high auto-ignition temperature of LPG is a serious advantage since the compression ratio of conventional Diesel engines can be maintained. The present contribution describes an experimental investigation conducted on a single cylinder DI Diesel engine, which has been properly modified to operate under LPG-Diesel blended fuel conditions, using LPG-Diesel blended fuels with various blended rates (0%, 10%, 20%, 30%, 40%). Comparative results are given for various engine speeds and loads for conventional Diesel and blended fuels, revealing the effect of blended fuel combustion on engine performance and exhaust emissions

  18. Assessment of maximum available work of a hydrogen fueled compression ignition engine using exergy analysis

    International Nuclear Information System (INIS)

    This work is aimed at study of maximum available work and irreversibility (mixing, combustion, unburned, and friction) of a dual-fuel diesel engine (H2 (hydrogen)–diesel) using exergy analysis. The maximum available work increased with H2 addition due to reduction in irreversibility of combustion because of less entropy generation. The irreversibility of unburned fuel with the H2 fuel also decreased due to the engine combustion with high temperature whereas there is no effect of H2 on mixing and friction irreversibility. The maximum available work of the diesel engine at rated load increased from 29% with conventional base mode (without H2) to 31.7% with dual-fuel mode (18% H2 energy share) whereas total irreversibility of the engine decreased drastically from 41.2% to 39.3%. The energy efficiency of the engine with H2 increased about 10% with 36% reduction in CO2 emission. The developed methodology could also be applicable to find the effect and scope of different technologies including exhaust gas recirculation and turbo charging on maximum available work and energy efficiency of diesel engines. - Highlights: • Energy efficiency of diesel engine increases with hydrogen under dual-fuel mode. • Maximum available work of the engine increases significantly with hydrogen. • Combustion and unburned fuel irreversibility decrease with hydrogen. • No significant effect of hydrogen on mixing and friction irreversibility. • Reduction in CO2 emission along with HC, CO and smoke emissions

  19. Pharmaceutical "charge compression" under the Medicare outpatient prospective payment system.

    Science.gov (United States)

    Braid, Mary Jo; Forbes, Kevin F; Moran, Donald W

    2004-01-01

    Analysis of the actual acquisition costs of a sample of pharmaceuticals demonstrates that payment rates for pharmaceutical therapies under the Medicare hospital outpatient prospective payment system (OPPS) are systematically biased against fully reimbursing high cost pharmaceutical therapies. Under the Centers for Medicare and Medicaid Services' (CMS') methodology, which assumes a constant markup, a bias in the cost estimate occurs when hospitals apply below average markups in establishing their charges for pharmaceutical products with above average costs. We developed a model of the relationship between product costs and charge markups. The logarithmic model shows that an increase in the acquisition cost per episode can be expected to lead to a reduction in the charge markup multiple. When markups for pharmaceuticals decline as acquisition cost increases, a rate-setting methodology that assumes a constant markup results in reimbursement for higher cost products that can be far below acquisition cost. The incentives in the payment system could affect site of care choices and beneficiary access. PMID:15151194

  20. The effects of using biodiesel on CI (compression ignition) engine and optimization of its production by using response surface methodology

    International Nuclear Information System (INIS)

    Bio-fuel production provides an alternative non-fossil fuel without the need to redesign current engine technology. This study presents an experimental investigation into the effects of using biodiesel blends on diesel engine performance and its emissions. The biodiesel fuels were produced from Sunflower oil using the transesterification process with low molecular weight alcohols and sodium hydroxide then tested on a steady state engine test rig using a Euro 4 four cylinder CI (compression ignition) engine. This study also shows how by blending biodiesel with diesel fuel at intervals of B5, B10, B15, and B20 can decrease harmful gas emissions significantly while maintaining similar performance output and efficiency. Production optimization was achieved by changing the variables which included methanol/oil molar ratio, NaOH catalyst concentration, reaction time, reaction temperature, and rate of mixing to maximize biodiesel yield. The technique used was the RSM (response surface methodology). In addition, a second-order model was developed to predict the biodiesel yield if the production criteria is known. The model was validated using additional experimental testing. It was determined that the catalyst concentration and molar ratio of methanol to sunflower oil were the most influential variables affecting percentage conversion to fuel and percentage initial absorbance. - Highlights: • The optimal conditions for the maximum methyl ester yield were found to be at methanol/oil molar ratio of 6.8:1. • NaOH catalyst concentration of 1.1%, reaction temperature 35 °C. • Rate of mixing 200 rpm and a minimum reaction time of 66 min. • The fuel properties were measured. • The combustion analysis, it was found the performance of the B20 was as good as that of standard diesel

  1. Hydrogen as an ignition-controlling agent for HCCI combustion engine by suppressing the low-temperature oxidation

    OpenAIRE

    Shudo, Toshio; Yamada, Hiroyuki

    2007-01-01

    Homogeneous charge compression ignition (HCCI) combustion enables internal combustion engines to achieve higher thermal efficiency and lower NOx emission than with conventional combustion systems. Controlling the ignition timing in accordance with the operating conditions is crucial for utilizing HCCI combustion engines. Adding hydrogen-containing gas is known to retard the autoignition of dimethyl ether (DME) considerably. The effective ignition control by hydrogen can expand the operation r...

  2. Control and diagnosis oriented modelling of the compression ignition engine; Modelisation du moteur a allumage par compression dans la perspective du controle et du diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Grondin, O.

    2004-12-15

    This thesis has described an investigation into the modelling of compression ignition engine for control and diagnosis purpose. The Diesel engine is the most efficient and clean internal combustion engine due to modem electromechanical actuators. However, pollutant emission regulations are much more stricter, thus, these complex systems need sophisticated and efficient control algorithms to reach very low emission levels. For this task, engine models are required at each step of the control system development: control laws synthesis, simulation and validation. The system under study is a six cylinder direct injection Diesel engine fitted with a turbocharger. The model of this system is based on physical laws for some parts of the engine such as cylinders, manifolds, turbocharger and crank-slider system. In order to reduce computing time we choose to model heat transfer and heat release during combustion using simple empirical correlations. Resulting model has been implemented in the Matlab-Simulink environment and it can predict variables of interest for control purpose with one degree crank angle resolution. The model has been tested numerically and compared with an industrial engine simulation code with good results. Moreover, model output variables are in good agreement with experimental data recorded on a heavy-duty research engine. The engine model has been embedded on a board providing enough computing performances to perform real-time simulations, this will be helpful for 'hardware-in-the-loop' simulations. Another part of this study is dedicated to the combustion process modelling using a non linear phenomenological model: the NARMAX model. The goal is to predict the in-cylinder pressure evolution using other measurements available on the engine. The NARMAX model parameters have been identified using input-output data carried out from the experimental engine. Such model is well suited for real-time applications compare to numerically cost

  3. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Charging of cylinders with a mixture of compressed... Packaging § 173.305 Charging of cylinders with a mixture of compressed gas and other material. (a) Detailed... nonpoisonous and nonflammable under this part must be shipped in cylinders as prescribed in § 173.304(a) or...

  4. Acceleration and Compression of Charged Particle Bunches Using Counter-Propagating Laser Beams

    International Nuclear Information System (INIS)

    The nonlinear interaction between counter-propagating laser beams in a plasma results in the generation of large (enhanced) plasma wakes. The two beams need to be slightly detuned in frequency, and one of them has to be ultra-short (shorter than a plasma period). Thus produced wakes have a phase velocity close to the speed of light and can be used for acceleration and compression of charged bunches. The physical mechanism responsible for the enhanced wake generation is qualitatively described and compared with the conventional laser wakefield mechanism. The authors also demonstrate that, depending on the sign of the frequency difference between the lasers, the enhanced wake can be used as a ''snow-plow'' to accelerate and compress either positively or negatively charged bunches. This ability can be utilized in an electron-positron injector

  5. The magPTOF diagnostic for shock-bang and compression-bang time measurement and charged-particles spectroscopy at the NIF

    Science.gov (United States)

    Han, H. W.; Sio, H.; Rinderknecht, H.; Frenje, J.; Zylstra, A.; Gatu Johnson, M.; Seguin, F.; Li, C.; Petrasso, R.; House, A.; Rygg, J. R.; Kimbrough, J.; Macphee, A.; Collins, G. W.; MacKinnon, A.; Le Pape, S.; Berzak Hopkins, L.; Bedzyk, M.; Magoon, J.; Shoup, M.; Sangster, C.; Kilkenny, J.; Olson, R.

    2015-11-01

    A magnetic particle-time-of-flight (MagPTOF) diagnostic has been fielded at the National Ignition Facility (NIF) for measurements of both shock- and compression-bang times. This type of measurement, combined with the measured shock-burn-weighted ρR, is used to understand shock convergence and implosion dynamics. The MagPTOF design is an upgrade to the existing particle time-of-flight (pTOF) diagnostic, which has recorded bang times in cryogenic DT implosions, DT exploding pushers and D3He implosions with accuracy better than 70 ps. The inclusion of a deflecting magnet should increase proton signal-to-background by a factor of 1000, allowing for measurements of shock bang time (using 14.7 MeV D3He protons) and compression bang time (using 2.45 MeV DD neutrons) in D3He-filled surrogate implosions. For exploding pushers with D3He, D2, T3He, or DT fuel, from which several charged fusion products escape, CR39 surrounding the CVD diamond detector can also be used for low-energy charged-particle spectroscopy. Implementation and initial data at the NIF will be discussed. This work is supported in part by DOE, LLNL, and LLE.

  6. Advances for laser ignition of internal combustion and rocket engines

    International Nuclear Information System (INIS)

    field laser physics. Unfortunately, there is no standard definition for the plasma threshold in the literature. Consequently, a clear definition of the focal volume is missing. For this reason it was tried to find a theoretical formula for the volume. This formula is based on the assumption that the focal volume encloses the space where the threshold intensity is higher than Ith =I0/2 or, alternatively, Ith = I0/e2. Laser energy transmission is one of the most important loss factors during plasma development by laser-induced optical breakdown and provides important information about the energy contained in the plasma. Hence, a number of plasma experiments were carried out. In our experiments is was found that for decreasing focal volume the plasma threshold energy (MPE) and the energy transmission can be reduced respectively. In order to investigate the possibility if laser-induced ignition can be made more efficient with respect to the laser pulse energy, several ignition experiments were performed. For these experiments a combustion chamber was employed at a filling pressure of 11 bar and a temperature of 110oC involving different focal sizes. The thermal ignition experiments were carried out to demonstrate in principle the feasibility of thermal ignition via resonant absorption of IR radiation. By evaluating these results with respect to laser ignition of engines, it is conceivable to employ laser thermal ignition as an innovative ignition mechanism. As in HCCI (homogeneous charge compression ignition) engines and rocket engines, ignition occurs at specific elevated pressures and temperatures, it can be assumed that the ignition energies are in the range between 20 to 100 mJ. Furthermore, different laser ignition system concepts were developed and evaluated regarding to their qualification for rocket engine ignition. As a consequence of its highest rating in our study, resonant ignition should be considered an interesting alternative to laser spark ignition. (author)

  7. Biodiesel production from Cynara cardunculus L. and Brassica carinata A. Braun seeds and their suitability as fuels in compression ignition engines

    Directory of Open Access Journals (Sweden)

    Stefania De Domenico

    2016-03-01

    Full Text Available The development of energy crops can provide environmental benefits and may represent an opportunity to improve agriculture in areas considered at low productivity. In this work, we studied the energy potential of two species (Brassica carinata A. Braun and Cynara cardunculus L. and their seed oil productivity under different growth conditions. Furthermore, the biodiesel from the oil extracted from the seeds of these species was produced and analysed in term of utilisation as fuels in compression ignition engines. In particular, the spray penetration and shape ratio were measured in a constant-volume chamber and compared with the results obtained with a standard diesel fuel. These results were obtained using a standard common rail injection system at different injection pressure, injection duration, and constant-volume chamber pressure.

  8. Energy deposition of ions in materials, and numerical simulations of compression, ignition, and burn of ion beam driven inertial confinement fusion pellets

    International Nuclear Information System (INIS)

    In this article various aspects of ion beam inertial confinement fusion are discussed. In particular a very thorough discussion of aspects of energy deposition of ions in hot plasmas and cold materials is given. Using energy deposition profiles given by these calculations, computer simulations of the compression, ignition and burn phases have been carried out for a single shell, pusher-tamper-DT fuel, multi-layered spherical pellet, suitable for use in a fusion reactor. The gain of this pellet was calculated to be 97 for an input energy of 7.38 MJ and an output energy of 715 MJ. This pellet has several other attractive features, including being environmentally attractive because of minimal radioactivity production and being insensitive to pusher-fuel instabilities. (orig.)

  9. Faddeev-Jackiw analysis for the charged compressible fluid in a higher-derivative electromagnetic field background

    CERN Document Server

    Mendes, Albert C R; Neto, Jorge Ananias; Takakura, Flavio I

    2016-01-01

    In the present paper we will discuss the Faddeev-Jackiw symplectic approach in the analysis of a charged compressible fluid immersed in a higher-derivative electromagnetic field theory. We have obtained the full set of constraints directly from the zero-mode eigenvectors. Besides, we have computed the Dirac brackets for the dynamic variables of the compressible fluid. Finally, as a result of the coupling between the charged compressible fluid and the electromagnetic field we have calculated two Dirac brackets between the fluid and electromagnetic fields, which are both zero when there is no coupling between them.

  10. Active flow control for maximizing performance of spark ignited stratified charge engines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Fedewa, Andrew; Stuecken, Tom; Timm, Edward; Schock, Harold J.; Shih, Tom-I.P.; Koochesfahani, Manooch; Brereton, Giles

    2002-10-15

    Reducing the cycle-to-cycle variability present in stratified-charge engines is an important step in the process of increasing their efficiency. As a result of this cycle-to-cycle variability, fuel injection systems are calibrated to inject more fuel than necessary, in an attempt to ensure that the engines fire on every cycle. When the cycle-to-cycle variability is lowered, the variation of work per cycle is reduced and the lean operating limit decreases, resulting in increased fuel economy. In this study an active flow control device is used to excite the intake flow of an engine at various frequencies. The goal of this excitation is to control the way in which vortices shed off of the intake valve, thus lowering the cycle-to-cycle variability in the flow field. This method of controlling flow is investigated through the use of three engines. The results of this study show that the active flow control device did help to lower the cycle-to-cycle variability of the in-cylinder flow field; however, the reduction did not translate directly into improved engine performance.

  11. Ignition-promoting effect of NO2 on methane, ethane and methane/ethane mixtures in a rapid compression machine

    DEFF Research Database (Denmark)

    Gersen, S.; Mokhov, A.V.; Darmeveil, J.H.;

    2011-01-01

    for the effects of NO2 addition to methane mixtures indicates that the ignition-promoting effect of NO2 is related to the appearance of new conversion channels for CH3 and CH3OO, i.e., NO2+CH3→NO+CH3O and NO+CH3OO→NO2+CH3O, generation of chain-initiating OH radicals through NO/NO2 interconversion, i......Autoignition delay times of stoichiometric methane, ethane and methane/ethane mixtures doped with 100 and 270ppm of NO2 have been measured in a RCM in the temperature range 900–1050K and pressures from 25 to 50bar. The measurements show that addition of NO2 to CH4/O2/N2/Ar and CH4/C2H6/O2/N2/Ar...... only a modest reduction in ignition delay time over the range of pressure and temperature measured. Computations with an updated chemical mechanism show good agreement with the measurements for undoped methane, but overpredict the delay times for undoped ethane and underestimate the effects of...

  12. Indications of flow near maximum compression in layered deuterium-tritium implosions at the National Ignition Facility

    Science.gov (United States)

    Gatu Johnson, M.; Knauer, J. P.; Cerjan, C. J.; Eckart, M. J.; Grim, G. P.; Hartouni, E. P.; Hatarik, R.; Kilkenny, J. D.; Munro, D. H.; Sayre, D. B.; Spears, B. K.; Bionta, R. M.; Bond, E. J.; Caggiano, J. A.; Callahan, D.; Casey, D. T.; Döppner, T.; Frenje, J. A.; Glebov, V. Yu.; Hurricane, O.; Kritcher, A.; LePape, S.; Ma, T.; Mackinnon, A.; Meezan, N.; Patel, P.; Petrasso, R. D.; Ralph, J. E.; Springer, P. T.; Yeamans, C. B.

    2016-08-01

    An accurate understanding of burn dynamics in implosions of cryogenically layered deuterium (D) and tritium (T) filled capsules, obtained partly through precision diagnosis of these experiments, is essential for assessing the impediments to achieving ignition at the National Ignition Facility. We present measurements of neutrons from such implosions. The apparent ion temperatures Tion are inferred from the variance of the primary neutron spectrum. Consistently higher DT than DD Tion are observed and the difference is seen to increase with increasing apparent DT Tion. The line-of-sight rms variations of both DD and DT Tion are small, ˜150 eV , indicating an isotropic source. The DD neutron yields are consistently high relative to the DT neutron yields given the observed Tion. Spatial and temporal variations of the DT temperature and density, DD-DT differential attenuation in the surrounding DT fuel, and fluid motion variations contribute to a DT Tion greater than the DD Tion, but are in a one-dimensional model insufficient to explain the data. We hypothesize that in a three-dimensional interpretation, these effects combined could explain the results.

  13. Engine performance, combustion, and emissions study of biomass to liquid fuel in a compression-ignition engine

    International Nuclear Information System (INIS)

    Highlights: • Renewable biomass to liquid (BTL) fuel was tested in a direct injection diesel engine. • Engine performance, in-cylinder pressure, and exhaust emissions were measured. • BTL fuel reduces pollutant emission for most conditions compared with diesel and biodiesel. • BTL fuel leads to high thermal efficiency and lower fuel consumption compared with diesel and biodiesel. - Abstract: In this work, the effects of diesel, biodiesel and biomass to liquid (BTL) fuels are investigated in a single-cylinder diesel engine at a fixed speed (2000 rpm) and three engine loads corresponding to 0 bar, 1.26 bar and 3.77 bar brake mean effective pressure (BMEP). The engine performance, in-cylinder combustion, and exhaust emissions were measured. Results show an increase in indicated work for BTL and biodiesel at 1.26 bar and 3.77 bar BMEP when compared to diesel but a decrease at 0 bar. Lower mechanical efficiency was observed for BTL and biodiesel at 1.26 bar BMEP but all three fuels had roughly the same mechanical efficiency at 3.77 bar BMEP. BTL was found to have the lowest brake specific fuel consumption (BSFC) and the highest brake thermal efficiency (BTE) among the three fuels tested. Combustion profiles for the three fuels were observed to vary depending on the engine load. Biodiesel was seen to have the shortest ignition delay among the three fuels regardless of engine loads. Diesel had the longest ignition delay at 0 bar and 3.77 bar BMEP but had the same ignition delay as BTL at 1.26 bar BMEP. At 1.26 bar and 3.77 bar BMEP, BTL had the lowest HC emissions but highest HC emissions at no load conditions when compared to biodiesel and diesel. When compared to diesel and biodiesel BTL had lower CO and CO2 emissions. At 0 bar and 1.26 bar BMEP, BTL had higher NOx emissions than diesel fuel but lower NOx than biodiesel at no load conditions. At the highest engine load tested, NOx emissions were observed to be highest for diesel fuel but lowest for BTL. At 1

  14. Decreasing the emissions of a partially premixed gasoline fueled compression ignition engine by means of injection characteristics and EGR

    Directory of Open Access Journals (Sweden)

    Nemati Arash

    2011-01-01

    Full Text Available This paper is presented in order to elucidate some numerical investigations related to a partially premixed gasoline fuelled engine by means of three dimensional CFD code. Comparing with the diesel fuel, gasoline has lower soot emission because of its higher ignition delay. The application of double injection strategy reduces the maximum heat release rate and leads to the reduction of NOx emission. For validation of the model, the results for the mean in-cylinder pressure, H.R.R., NOx and soot emissions are compared with the corresponding experimental data and show good levels of agreement. The effects of injection characteristics such as, injection duration, spray angle, nozzle hole diameter, injected fuel temperature and EGR rate on combustion process and emission formation are investigated yielding the determination of the optimal point thereafter. The results indicated that optimization of injection characteristics leads to simultaneous reduction of NOx and soot emissions with negligible change in IMEP.

  15. A Review of Sub-Scale Test Methods to Evaluate the Friction and Wear of Ring and Liner Materials for Spark- and Compression Ignition Engines

    Energy Technology Data Exchange (ETDEWEB)

    Blau, P.J.

    2002-01-22

    A review was conducted of past laboratory-scale test methods and to assess their validity for ranking materials and lubricants for use as piston and liner materials in compression-ignition (CI) and spark-ignition (SI) engines. Most of the previous work was aimed at simulating SI engine environments. This report begins with a discussion of the numerous factors that can affect the validity of an approach to simulating engine conditions in a laboratory. These include not only mechanical, chemical and thermal factors, but also human factors as regards how the vehicle is operated and maintained. The next section provides an annotated review of open literature publications that address the issues of laboratory simulation of engine components. A comparison of these studies indicates a lack of sufficient standardization in procedures to enable a systematic comparison of one publication to another. There were just a few studies that compared several laboratory test methods to engine test results, and these indicated that some test methods correlate, at least qualitatively, better than others. The last section provides a series of recommendations for improving the accuracy and validity of laboratory-scale simulations of engine behavior. It became clear that much of the engine wear damage occurs during start-up when the engine is cold, and this calls into the question the usefulness of test methods that attempt to simulate steady-state running conditions. It is recommended that a new standard test method, perhaps developed with the help of the ASTM wear and erosion committee, be developed. It would use cold start-up conditions in the presence of degraded oil, or simulated degraded oil.

  16. Evaluation of the necessity of exhaust gas recirculation employment for a methanol/diesel reactivity controlled compression ignition engine operated at medium loads

    International Nuclear Information System (INIS)

    Highlights: • Methanol fraction considerably affected the engine performance. • Exhaust gases had little effect on fuel efficiency at a fixed ignition timing. • Good performance was obtained without exhaust gases at low initial temperature. • The introduction of exhaust gases was essential when initial temperature is high. - Abstract: Three-dimensional computational fluid dynamics simulation was conducted to investigate the improvement of engine performance by managing exhaust gas recirculation rate and methanol fraction in a methanol/diesel reactivity controlled compression ignition engine. By defining fuel efficiency and ringing intensity as the restricted boundaries, the operating ranges of exhaust gas recirculation rate and methanol fraction under various initial temperatures were determined to simultaneously achieve high fuel economy and avoid engine knock. The results indicated that the fuel efficiency and ringing intensity were dominantly affected by the combustion phasing, and they was nearly insensitive to the variations of exhaust gas recirculation rate and initial temperature at a constant combustion phasing. The necessity of exhaust gas recirculation employment at medium loads was dependent on the level of initial temperature. When initial temperature was less than the critical value (380 K in this study), optimal engine performance could be achieved by only adopting high methanol fraction without introducing exhaust gas recirculation. Once initial temperature was beyond the critical value, exhaust gas recirculation was imperative to avoid excessive ringing intensity. Through simultaneously optimizing methanol fraction and exhaust gas recirculation rate, the combined strategy exhibited more advantages in fuel efficiency, nitrogen oxides, and ringing intensity under a wide range of initial temperature

  17. A Review of Sub-Scale Test Methods to Evaluate the Friction and Wear of Ring and Liner Materials for Spark-and Compression Ignition Engines; TOPICAL

    International Nuclear Information System (INIS)

    A review was conducted of past laboratory-scale test methods and to assess their validity for ranking materials and lubricants for use as piston and liner materials in compression-ignition (CI) and spark-ignition (SI) engines. Most of the previous work was aimed at simulating SI engine environments. This report begins with a discussion of the numerous factors that can affect the validity of an approach to simulating engine conditions in a laboratory. These include not only mechanical, chemical and thermal factors, but also human factors as regards how the vehicle is operated and maintained. The next section provides an annotated review of open literature publications that address the issues of laboratory simulation of engine components. A comparison of these studies indicates a lack of sufficient standardization in procedures to enable a systematic comparison of one publication to another. There were just a few studies that compared several laboratory test methods to engine test results, and these indicated that some test methods correlate, at least qualitatively, better than others. The last section provides a series of recommendations for improving the accuracy and validity of laboratory-scale simulations of engine behavior. It became clear that much of the engine wear damage occurs during start-up when the engine is cold, and this calls into the question the usefulness of test methods that attempt to simulate steady-state running conditions. It is recommended that a new standard test method, perhaps developed with the help of the ASTM wear and erosion committee, be developed. It would use cold start-up conditions in the presence of degraded oil, or simulated degraded oil

  18. Thermal Charging Study of Compressed Expanded Natural Graphite/Phase Change Material Composites

    Energy Technology Data Exchange (ETDEWEB)

    Mallow, Anne M [ORNL; Abdelaziz, Omar [ORNL; Graham, Samuel [Georgia Institute of Technology, Atlanta

    2016-01-01

    The thermal charging performance of phase change materials, specifically paraffin wax, combined with compressed expanded natural graphite foam is studied under constant heat flux and constant temperature conditions. By varying the heat flux between 0.39 W/cm2 and 1.55 W/cm2 or maintaining a boundary temperature of 60 C for four graphite foam bulk densities, the impact on the rate of thermal energy storage is discussed. Thermal charging experiments indicate that thermal conductivity of the composite is an insufficient metric to compare the influence of graphite foam on the rate of thermal energy storage of the PCM composite. By dividing the latent heat of the composite by the time to melt for various boundary conditions and graphite foam bulk densities, it is determined that bulk density selection is dependent on the applied boundary condition. A greater bulk density is advantageous for samples exposed to a constant temperature near the melting temperature as compared to constant heat flux conditions where a lower bulk density is adequate. Furthermore, the anisotropic nature of graphite foam bulk densities greater than 50 kg/m3 is shown to have an insignificant impact on the rate of thermal charging. These experimental results are used to validate a computational model for future use in the design of thermal batteries for waste heat recovery.

  19. An image compression method for space multispectral time delay and integration charge coupled device camera

    International Nuclear Information System (INIS)

    Multispectral time delay and integration charge coupled device (TDICCD) image compression requires a low-complexity encoder because it is usually completed on board where the energy and memory are limited. The Consultative Committee for Space Data Systems (CCSDS) has proposed an image data compression (CCSDS-IDC) algorithm which is so far most widely implemented in hardware. However, it cannot reduce spectral redundancy in multispectral images. In this paper, we propose a low-complexity improved CCSDS-IDC (ICCSDS-IDC)-based distributed source coding (DSC) scheme for multispectral TDICCD image consisting of a few bands. Our scheme is based on an ICCSDS-IDC approach that uses a bit plane extractor to parse the differences in the original image and its wavelet transformed coefficient. The output of bit plane extractor will be encoded by a first order entropy coder. Low-density parity-check-based Slepian—Wolf (SW) coder is adopted to implement the DSC strategy. Experimental results on space multispectral TDICCD images show that the proposed scheme significantly outperforms the CCSDS-IDC-based coder in each band

  20. A Comparative study on VOCs and aldehyde-ketone emissions from a spark Ignition vehicle fuelled on compressed natural gas and gasoline

    International Nuclear Information System (INIS)

    In this work, an experimental study was conducted on a spark ignition (SI) vehicle fuelled on compressed natural gas (CNG), and gasoline to compare the unregulated emissions such as volatile organic compounds (VOCs) and aldehyde-ketones or carbonyls. In the meantime, ozone forming potential (OFP) of pollutants was also calculated on the basis of their specific reactivity (SR). The vehicle was run on a chassis dynamometer following the Chinese National Standards test scheduled for light duty vehicle (LDV) emissions. According to the results, total aldehyde-ketones were increased by 39.4% due to the substantial increase in formaldehyde and acrolein + acetone emissions, while VOCs and BTEX (benzene, toluene, ethyl benzene, and xylene) reduced by 85.2 and 86% respectively, in case of CNG fuelled vehicle as compared to gasoline vehicle. Although total aldehyde-ketones were higher with CNG relative to gasoline, their SR was lower due decrease in acetaldehyde, propionaldehyde, crotonaldehyde, and methacrolein species having higher maximum incremental reactivity (MIR) values. The SR of VOCs and aldehyde-ketones emitted from CNG fuelled vehicle was decreased by above 10% and 32% respectively, owing to better physicochemical properties and more complete burning of CNG as compared to gasoline. (author)

  1. Possibilities of the use of camelina and mustard methyl esters and their mixtures with diesel as a fuel for compression ignition engines

    Directory of Open Access Journals (Sweden)

    Marta Ambrosewicz-Walacik

    2015-03-01

    Full Text Available The aim of the study was to evaluate the use of camelina and mustard methyl esters and their mixtures with diesel (in 95:5 and 80:20 proportion as fuels for compression ignition engines. Esters prepared with acid-base transesterification process methyl were characterized in terms of the lipid composition, kinematic viscosity at 40°C, density at 15°C, acid value, particulate matter content, sulphur content, flash point, cold filter plugging point and oxidative stability at 110°C. It has been shown that the majority of the analysed methyl esters discriminates, with the exception of the particulate matter content, meet the requirements of PN-EN 14214 (2012. In case of methyl ester and ON mixtures it has been found that the 5% addition of esters slightly contributed to the changes in physic-chemical properties, compared to diesel fuel, while 20% addition resulted in an increase of value of the tested discriminates. In general, it has been also found that the only discriminates disqualifying the usage of those samples as fuels for diesel engines was too high particulate matter content.

  2. Effect of fuel oxygen on the energetic and exergetic efficiency of a compression ignition engine fuelled separately with palm and karanja biodiesels

    International Nuclear Information System (INIS)

    Exergy analysis of any thermodynamic system can take care of the limitations of energy analysis such as irreversible losses, their magnitude and the source of thermodynamic inefficiencies apart from energy losses. In the present study, both the analyses along with heat release analysis are conducted on a natural aspirated diesel engine fuelled separately with palm biodiesel (PB), karanja biodiesel (KB), and petrodiesel (PD) using the experimental data. Since the engine performs best at about 85% loading condition, the energetic and exergetic performance parameters of the engine are evaluated at 85% loading condition for each type of fuel. The aim of the study is to determine the effect of fuel oxygen on energy and exergy efficiencies of a CI (compression ignition) engine. Various exergy losses, exergy destruction and their ratios associated with the heat transfer through cooling water, radiation, exhaust gas, friction, and some uncounted exergy destruction are investigated. Apart from exergy loss due to heat transfer; the uncounted exergy destruction (due to combustion) also plays a major role in the system inefficiency. Based on the comparative assessment of the obtained results, it is concluded that a better combustion with less irreversibility is possible with the increase in O2 content in the fuel. - Highlights: • Efficiency of a CI engine increases with the increase in oxygen quantity in the fuel. • Irreversibility of a CI engine decreases with increase in oxygen content in the fuel. • Palm biodiesel performs better than karanja biodiesel and petrodiesel for a CI engine

  3. Experimental Analysis of Performance and Emission Parameters of Neem Oil Ethyl Ester and HHO Gas Addition with Neem Oil Ethyl Ester in a Single Cylinder Four Stroke Compression Ignition Engine

    OpenAIRE

    M. Subramanian

    2014-01-01

    Need for alternate fuel is increasing day by day due various problems associated with the conventional fuels. Present work is focussed on analysing experimentally the performance and emission characteristics of Neem oil biodiesel and addition of HHO gas along with Neem oil biodiesel in a single cylinder compression ignition engine. Biodiesel is extracted by tranesterification of non edible crude Neem oil using ethanol and Naoh as catalyst. The biodiesel is blended with diesel. ...

  4. A computational investigation of diesel and biodiesel combustion and NOx formation in a light-duty compression ignition engine

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zihan; Srinivasan, Kalyan K.; Krishnan, Sundar R.; Som, Sibendu

    2012-04-24

    Diesel and biodiesel combustion in a multi-cylinder light duty diesel engine were simulated during a closed cycle (from IVC to EVO), using a commercial computational fluid dynamics (CFD) code, CONVERGE, coupled with detailed chemical kinetics. The computational domain was constructed based on engine geometry and compression ratio measurements. A skeletal n-heptane-based diesel mechanism developed by researchers at Chalmers University of Technology and a reduced biodiesel mechanism derived and validated by Luo and co-workers were applied to model the combustion chemistry. The biodiesel mechanism contains 89 species and 364 reactions and uses methyl decanoate, methyl-9- decenoate, and n-heptane as the surrogate fuel mixture. The Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) spray breakup model for diesel and biodiesel was calibrated to account for the differences in physical properties of the fuels which result in variations in atomization and spray development characteristics. The simulations were able to capture the experimentally observed pressure and apparent heat release rate trends for both the fuels over a range of engine loads (BMEPs from 2.5 to 10 bar) and fuel injection timings (from 0° BTDC to 10° BTDC), thus validating the overall modeling approach as well as the chemical kinetic models of diesel and biodiesel surrogates. Moreover, quantitative NOx predictions for diesel combustion and qualitative NOx predictions for biodiesel combustion were obtained with the CFD simulations and the in-cylinder temperature trends were correlated to the NOx trends."

  5. Effect of the use of olive–pomace oil biodiesel/diesel fuel blends in a compression ignition engine: Preliminary exergy analysis

    International Nuclear Information System (INIS)

    Highlights: • Olive–pomace oil (OPO) biodiesel constitute a new second-generation biofuel. • Exergy efficiency and performance of OPO biodiesel, straight and blended with diesel fuel was evaluated. • OPO biodiesel, straight and blended, provided similar performance parameters. • OPO biodiesel, straight and blended, provided similar exergy efficiency compared to diesel fuel. • OPO biodiesel, straight and blended, provided no exergy cost increment compared to diesel fuel. - Abstract: Although biodiesel is among the most studied biofuels for diesel engines, it is usually produced from edible oils, which gives way to controversy between the use of land for fuel and food. For this reason, residues like olive–pomace oil are considered alternative raw materials to produce biodiesel that do not compete with the food industry. To gain knowledge about the implications of its use, olive–pomace oil methyl ester, straight and blended with diesel fuel, was evaluated as fuel in a direct injection diesel engine Perkins AD 3-152 and compared to the use of fossil diesel fuel. Performance curves were analyzed at full load and different speed settings. To perform the exergy balance of the tested fuels, the operating conditions corresponding to maximum engine power values were considered. It was found that the tested fuels offer similar performance parameters. When straight biodiesel was used instead of diesel fuel, maximum engine power decreased to 5.6%, while fuel consumption increased up to 7%. However, taking into consideration the Second Law of the Thermodynamics, the exergy efficiency and unitary exergetic cost reached during the operation of the engine under maximum power condition for the assessed fuels do not display significant differences. Based on the exergy results, it may be concluded that olive–pomace oil biodiesel and its blends with diesel fuel may substitute the use of diesel fuel in compression ignition engines without any exergy cost increment

  6. Combined effects of cooled EGR and a higher geometric compression ratio on thermal efficiency improvement of a downsized boosted spark-ignition direct-injection engine

    International Nuclear Information System (INIS)

    Highlights: • Experiments for the effects of cooled EGR and two compression ratios (CR) on fuel efficiency were conducted. • The mechanism for the observed fuel efficiency behaviors by cooled EGR and high CR was clarified. • Cooled EGR offers more fuel efficiency improvement than elevating CR from 9.3 to 10.9. • Combining 18–25% cooled EGR with 10.9 CR lead to 2.1–3.5% brake thermal efficiency improvements. - Abstract: The downsized boosted spark-ignition direct-injection (SIDI) engine has proven to be one of the most promising concepts to improve vehicle fuel economy. However, the boosted engine is typically designed at a lower geometric compression ratio (CR) due to the increased knock tendency in comparison to naturally aspirated engines, limiting the potential of improving fuel economy. On the other hand, cooled exhaust gas recirculation (EGR) has drawn attention due to the potential to suppress knock and improve fuel economy. Combing the effects of boosting, increased CR and cooled EGR to further improve fuel economy within acceptable knock tolerance has been investigated using a 2.0 L downsized boosted SIDI engine over a wide range of engine operating conditions from 1000 rpm to 3000 rpm at low to high loads. To clarify the mechanism of this complicated effects, the first law of thermodynamics analysis was conducted with the inputs from GT-Power® engine simulation. Experiment results indicate that cooled EGR provides more brake thermal efficiency improvement than increasing geometric CR from 9.3 to 10.9. The benefit of brake thermal efficiency from the higher CR is limited to low load conditions. The attributes for improving brake thermal efficiency by cooled EGR include reduced heat transfer loss, reduced pumping work and increased ratio of specific heats for all the engine operating conditions, as well as higher degree of constant volume heat release only for the knock-limited high load conditions. The combined effects of 18–25% cooled EGR

  7. 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.

  8. 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.

  9. Charge-exchange and fusion reaction measurements during compression experiments with neutral beam heating in the Tokamak Fusion Test Reactor

    International Nuclear Information System (INIS)

    Adiabatic toroidal compression experiments were performed in conjunction with high power neutral beam injection in the Tokamak Fusion Test Reactor (TFTR). Acceleration of beam ions to energies nearly twice the injection energy was measured with a charge-exchange neutral particle analyzer. Measurements were also made of 2.5 MeV neutrons and 15 MeV protons produced in fusion reactions between the deuterium beam ions and the thermal deuterium and 3He ions, respectively. When the plasma was compressed, the d(d,n)3He fusion reaction rate increased a factor of five, and the 3He(d,p)4He rate by a factor of twenty. These data were simulated with a bounce-averaged Fokker-Planck program, which assumed conservation of angular momentum and magnetic moment during compression. The results indicate that the beam ion acceleration was consistent with adiabatic scaling

  10. IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES

    Energy Technology Data Exchange (ETDEWEB)

    Jason M. Keith

    2005-02-01

    This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

  11. Fast Ignition Experimental and Theoretical Studies

    Energy Technology Data Exchange (ETDEWEB)

    Akli, K

    2006-10-20

    We are becoming dependent on energy more today than we were a century ago, and with increasing world population and booming economies, sooner or later our energy sources will be exhausted. Moreover, our economy and welfare strongly depends on foreign oil and in the shadow of political uncertainties, there is an urgent need for a reliable, safe, and cheap energy source. Thermonuclear fusion, if achieved, is that source of energy which not only will satisfy our demand for today but also for centuries to come. Today, there are two major approaches to achieve fusion: magnetic confinement fusion (MFE) and inertial confinement fusion (ICF). This dissertation explores the inertial confinement fusion using the fast ignition concept. Unlike the conventional approach where the same laser is used for compression and ignition, in fast ignition separate laser beams are used. This dissertation addresses three very important topics to fast ignition inertial confinement fusion. These are laser-to-electron coupling efficiency, laser-generated electron beam transport, and the associated isochoric heating. First, an integrated fast ignition experiment is carried out with 0.9 kJ of energy in the compression beam and 70 J in the ignition beam. Measurements of absolute K{sub {alpha}} yield from the imploded core revealed that about 17% of the laser energy is coupled to the suprathermal electrons. Modeling of the transport of these electrons and the associated isochoric heating, with the previously determined laser-to-electron conversion efficiency, showed a maximum target temperature of 166 eV at the front where the electron flux is higher and the density is lower. The contribution of the potential, induced by charge separation, in opposing the motion of the electrons was moderate. Second, temperature sensitivity of Cu K{sub {alpha}} imaging efficiency using a spherical Bragg reflecting crystal is investigated. It was found that due to the shifting and broadening of the K{sub {alpha

  12. Tunable proton stopping power of deuterium-tritium by mixing heavy ion dopants for fast ignition

    Science.gov (United States)

    Zou, D. B.; Hu, L. X.; Wang, W. Q.; Yang, X. H.; Yu, T. P.; Zhang, G. B.; Ouyang, J. M.; Shao, F. Q.; Zhuo, H. B.

    2016-03-01

    The theoretical model of charged-particle stopping power for the Coulomb logarithm lnΛb ≥ 2 plasma [Phys. Rev. Lett., 20, 3059 (1993)] is extended to investigate the transport of the energetic protons in a compressed deuterium-tritium (DT) pellet mixed with heavy ion dopants. It shows that an increase of mixed-ion charge state and density ratio results in the substantial enhancement of the proton stopping power, which leads to a shorter penetration distance and an earlier appearance of the Bragg peak with a higher magnitude. The effect of hot-spot mix on the proton-driven fast ignition model is discussed. It is found that ignition time required for a small mixed hot-spot can be significantly reduced with slightly increased beam energy. Nevertheless, the ignition cannot maintain for a long time due to increasing alpha-particle penetration distance and energy loss from mechanical work and thermal conduction at high temperatures.

  13. Fuels for homogeneous, self-igniting combustion processes; Brennstoffe fuer homogene selbstgezuendete Verbrennungsprozesse - Jahresbericht 2008

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, B.; Boulouchos, K.

    2008-07-01

    This annual report for the year 2008 for the Swiss Federal Office of Energy (SFOE) reviews work done at the Swiss Federal Institute of Technology in Zurich, Switzerland, concerning the theoretical and experimental study of self-igniting fuel-air combustion processes that occur in HCCI (Homogeneous Charge Compression Ignition) engines. The work done in 2008 is reviewed, including the systematic search for better injection strategies and cylinder head design. Over 100 intricate calculation runs were made, each needing more than a day of computation and evaluation time. Experimental work in the institute's engine laboratory is also reviewed.

  14. Ignitor with stable low-energy thermite igniting system

    Science.gov (United States)

    Kelly, Michael D.; Munger, Alan C.

    1991-02-05

    A stable compact low-energy igniting system in an ignitor utilizes two components, an initiating charge and an output charge. The initiating charge is a thermite in ultra-fine powder form compacted to 50-70% of theoretical maximum density and disposed in a cavity of a header of the ignitor adjacent to an electrical ignition device, or bridgewire, mounted in the header cavity. The initiating charge is ignitable by operation of the ignition device in a hot-wire mode. The output charge is a thermite in high-density consoladated form compacted to 90-99% of theoretical maximum density and disposed adjacent to the initiating charge on an opposite end thereof from the electrical ignition device and ignitable by the initiating charge. A sleeve is provided for mounting the output charge to the ignitor header with the initiating charge confined therebetween in the cavity.

  15. Combustion and emission characteristics of jet controlled compression ignition engine at different loads%射流控制压缩着火发动机不同负荷下燃烧及排放特性

    Institute of Scientific and Technical Information of China (English)

    张强; 杨培源; 隆武强; 田江平

    2016-01-01

    针对柴油预混合气着火相位难以直接控制的问题,提出射流控制压缩着火(jet controlled compression ignition, JCCI)方式。将一台单缸农用柴油机改造为JCCI发动机:压缩比降至12,增加一个带液化石油气(liquefied petroleum gas, LPG)供给通道和火花塞的点火室,并进行了JCCI发动机全负荷特性试验研究。试验结果表明:采用射流控制压缩着火方式可以有效控制发动机的燃烧相位和排放。在平均有效压力低于0.44 MPa的工况范围,NOx排放比原机降低较多,燃烧始点相位CA10与滞燃期几乎不随负荷增加而改变;在平均有效压力高于0.44直至0.54 MPa负荷范围内,燃烧始点相位迅速前移,滞燃期迅速减小,柴油提前自燃,射流对着火相位控制作用减弱,NOx排放迅速增加并超过原机;在全负荷范围,烟度始终维持在低水平,HC和CO排放较高。该研究可为柴油预混合燃烧着火相位控制提供参考。%One of the key points in diesel premixed combustion is the realization of combustion phasing control. The sensitivity of diesel to temperature and equivalent ratio was the crucial obstacle. In order to directly control the diesel premixed combustion phasing, a novel method called the jet controlled compression ignition (JCCI) for diesel premixed compression ignition was proposed. A single cylinder diesel engine was modified to study the JCCI system. First, a small ignition chamber comprising a gas fuel injector and a spark plug was mounted on the cylinder head in this diesel engine. Six small orifices were used to connect the ignition chamber and the main chamber. Furthermore, the compression ratio was reduced to 12 to avoid the auto-ignition of the premixed diesel fuel. Experiments were conducted on the JCCI engine under overall loads at a constant speed to study the trend of combustion and the emission characteristics of JCCI system. The results showed that

  16. Desensitizing nano powders to electrostatic discharge ignition

    Energy Technology Data Exchange (ETDEWEB)

    Steelman, Ryan [Texas Tech Univ., Lubbock, TX (United States). Dept. of Mechanical Engineering; Clark, Billy [Texas Tech Univ., Lubbock, TX (United States). Dept. of Mechanical Engineering; Pantoya, Michelle L. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Mechanical Engineering; Heaps, Ronald J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Daniels, Michael A. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-08-01

    Electrostatic discharge (ESD) is a main cause for ignition in powder media ranging from grain silos to fireworks. Nanoscale particles are orders of magnitude more ESD ignition sensitive than their micron scale counterparts. This study shows that at least 13 vol. % carbon nanotubes (CNT) added to nano-aluminum and nano-copper oxide particles (nAl + CuO) eliminates ESD ignition sensitivity. The CNT act as a conduit for electric energy and directs electric charge through the powder to desensitize the reactive mixture to ignition. For nanoparticles, the required CNT concentration for desensitizing ESD ignition acts as a diluent to quench energy propagation.

  17. A novel charged-particle diagnostic for compression in inertial confinement fusion targets

    International Nuclear Information System (INIS)

    A new technique for diagnosing compression in multiple regions of inertial confinement fusion targets is discussed. This diagnostic uses knock-on deuterons and protons that have been elastically scattered by 14.1 MeV deuterium-tritium (DT) fusion neutrons. The target is composed of three different materials: DT gas contained in a plastic shell overcoated by deuterated plastic. The effect on the knock-on deuteron spectrum of mixing of these layers from hydrodynamic instabilities is also discussed. (c) 2000 American Institute of Physics

  18. Energy production by microexplosions in highly compressed plutonium microspheres by laser or charged particle beams

    International Nuclear Information System (INIS)

    The present work analysis the energy liberation during a microexplosion of a superprompt-critical plutonium microsphere having a massa of m = 0,52 g, compressed to a density 235 times the normal density of plutonium. The calculation for the microexplosion are performed by solving the neutron transport equation coupled in time to the hydrodynamics and thermodynamics equations for the plutonium plasma. Thermal radiation transfer is handled by the use of the conduction approximation for the radiation transport equation. This work emphasized the pratical uses of the microexplosions. (author)

  19. 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.

  20. Compression ratio effect on methane HCCI combustion

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S. M.; Pitz, W.; Smith, J. R.; Westbrook, C.

    1998-09-29

    We have used the HCT (Hydrodynamics, Chemistry and Transport) chemical kinetics code to simulate HCCI (homogeneous charge compression ignition) combustion of methane-air mixtures. HCT is applied to explore the ignition timing, bum duration, NOx production, gross indicated efficiency and gross IMEP of a supercharged engine (3 atm. Intake pressure) with 14:1, 16:l and 18:1 compression ratios at 1200 rpm. HCT has been modified to incorporate the effect of heat transfer and to calculate the temperature that results from mixing the recycled exhaust with the fresh mixture. This study uses a single control volume reaction zone that varies as a function of crank angle. The ignition process is controlled by adjusting the intake equivalence ratio and the residual gas trapping (RGT). RGT is internal exhaust gas recirculation which recycles both thermal energy and combustion product species. Adjustment of equivalence ratio and RGT is accomplished by varying the timing of the exhaust valve closure in either 2-stroke or 4-stroke engines. Inlet manifold temperature is held constant at 300 K. Results show that, for each compression ratio, there is a range of operational conditions that show promise of achieving the control necessary to vary power output while keeping indicated efficiency above 50% and NOx levels below 100 ppm. HCT results are also compared with a set of recent experimental data for natural gas.

  1. Promotion of charge transport in low-temperature fabricated TiO2 electrodes by curing-induced compression stress

    International Nuclear Information System (INIS)

    In low-temperature fabricated dye-sensitized solar cells, promotion of the interparticle electronic connectivity, reduction of the trapping/detrapping events, and suppression of charge recombination on the semiconductor–electrolyte interface are key steps to improve charge collection and energy conversion efficiency. In this work, a new method based on curing cementing material (Ca(OH)2) under CO2 ambient to produce uniform CaCO3 coatings on mesoporous TiO2 nanoparticulate films is presented. The volume shrinkage resulting from the phase conversion of calcareous coating during the curing procedure can produce strong strain on the TiO2 electrode. By virtue of the compression stress, the interparticle electronic connectivity was promoted and the density of electronic states in the bandgap of the semiconductor was reduced. Thus, the electrode with CaCO3 coating exhibits better performance for diffusion and collection of electrons. Moreover, the formed CaCO3 coatings can also prevent the electrons from recombination on the semiconductor–electrolyte interface. In combination with a platinized electrode and electrolyte, the photovoltaic devices with CaCO3 coated electrode achieved an energy conversion efficiency of 4.79%, which is 40% higher than that of the cell with blank electrode

  2. Influencia de Algunos Parámetros sobre el Ciclo de un Motor de Encendido por Compresión Effect of Some Parameters on the Performance of a Compression Ignition Engine

    Directory of Open Access Journals (Sweden)

    Carlos G Villamar

    2009-01-01

    Full Text Available Se presentan una serie de estudios paramétricos sobre el ciclo termodinámico del motor de encendido por compresión empleando para ello un programa de computación. El programa permite estudiar el ciclo considerando la variación de la composición y propiedades del fluido de trabajo debidas a la presión, temperatura y riqueza de la mezcla. Se han efectuado estudios sobre la influencia de los principales índices del motor sobre la presión y temperatura promedio de los gases presentes en el cilindro. Entre estos se ha considerado, el ángulo de inicio, el adelanto y duración del proceso de combustión, la riqueza y la recirculación de gases. Se concluye que si aumenta la duración de la combustión se debe incrementar la riqueza para mantener la potencia y que la recirculación de gases produce una reducción de las emisiones de óxidos nitrosos.Some parametric studies on the thermodynamic cycle of a compression ignition engine by using a computer program that allows to analyze the cycle considering variations of working fluid composition and fluid properties due to pressure, temperature and fuel/air ratio. Studies on the influence of main indexes of the engine on the average pressure and temperature of the gases in the cylinder were done. Among these, the starting angle, the ignition time and duration of the combustion, the equivalence ratio, and gas recirculation, were considered. It is concluded that an increase in combustion duration implies a richness increase to maintain the power, and that nitrogen oxide emissions are reduced by gas recirculation.

  3. Bulkhead chamber ignition for internal combustion engines. Schottkammerzuendung fuer Verbrennungsmotore

    Energy Technology Data Exchange (ETDEWEB)

    Fox, G.

    1990-12-06

    Bulkhead chamber ignition makes for reliable ignition of different fuels (e.g. petrol or diesel) in internal combustion engines (multifuel engine) that can be operated with an extremely lean fuel-air mixture. This is realized by an open chamber (referred to as bulkhead chamber in the following) inside the combustion chamber which diverts a fraction of the compressed fuel-air mixture from the combustion chamber. After this the pressure in the bulkhead chamber is increased until the mixture ignites spontaneously. The combustion pressure drives back the piston and opens the bulkhead chamber. Then the compressed fuel-air mixture in the combustion chamber is ignited by the released combustion gas.

  4. Exergetic Evaluation of Speed and Load Effects in Spark Ignition Engines Évaluation exergétique des effets de la vitesse et de la charge dans les moteurs àallumage par étincelle

    Directory of Open Access Journals (Sweden)

    Sezer I.

    2012-08-01

    Full Text Available This study investigates the effects of various operating conditions in spark ignition engines via an exergy analysis. A thermodynamic cycle model including compression, combustion and expansion processes was used for investigation. Induction and exhaust processes were computed with a simple approximation method. The principles of the second law were applied to the cycle model to perform the exergy analysis. Exergetic variables, i.e., the exergy transfers with heat and work, irreversibilities, thermomechanical exergy, fuel chemical exergy and total exergy were calculated in the exergy analysis. Variation of the exergetic parameters and the distribution of them into the fuel exergy were determined for various operating conditions, i.e., engine speed and load. The first and second law efficiencies and specific fuel consumption were also computed to reveal the optimum operating conditions. The results show that the exergy transfer with heat decreases and the exergy transfer with exhaust gases increases with increasing engine speed. Engine speed of 3 000 rpm gives the maximum exergy transfer as work, the minimum irreversibility and the best efficiency and fuel consumption. Exergy transfers with heat, work and exhaust and irreversibilities increase with increasing engine load. Additionally, the first and second law efficiencies increase and fuel consumption decreases with increasing engine load, so a high engine load gives the best efficiency and fuel consumption. Cette étude examine les effets des différentes conditions de fonctionnement de moteurs à allumage commandé via une analyse exergétique. Un modèle de cycle thermodynamique comprenant les processus de compression, combustion et détente a été utilisé. Les processus d’admission et d’échappement sont modélisés à l’aide d’une méthode simple d’approximation. Les principes de la deuxième loi de la thermodynamique ont été appliqués au modèle de cycle pour effectuer l

  5. 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.

  6. Laser-plasma interactions for fast ignition

    OpenAIRE

    Kemp, A. J.; Fiuza, F.; Debayle, A.; Johzaki, T.; Mori, W. B.; P.K. Patel; Sentoku, Y.; Silva, L. O.

    2014-01-01

    In the electron-driven fast-ignition approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser plasma interactions (LPI) relevant to fast ignition. Increases in computational and modeling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multi-dimensi...

  7. Experimental Analysis of Performance and Emission Parameters of Neem Oil Ethyl Ester and HHO Gas Addition with Neem Oil Ethyl Ester in a Single Cylinder Four Stroke Compression Ignition Engine

    Directory of Open Access Journals (Sweden)

    M Subramanian

    2014-04-01

    Full Text Available Need for alternate fuel is increasing day by day due various problems associated with the conventional fuels. Present work is focussed on analysing experimentally the performance and emission characteristics of Neem oil biodiesel and addition of HHO gas along with Neem oil biodiesel in a single cylinder compression ignition engine. Biodiesel is extracted by tranesterification of non edible crude Neem oil using ethanol and Naoh as catalyst. The biodiesel is blended with diesel. The blends used are N30 and N40. HHO gas is produced from the process of electrolysis the HHO gas is the combination of hydrogen and oxygen. The produced gas is made to pass through a moisture separator and sent along the intake manifold with the intake air. The performance and emission characteristics are noted down and compared. It was observed that there was a rise in brake thermal efficiency and lesser specific fuel consumption, Reduced Oxygen content in exhaust gases, lesser HC and CO emission and there was a rise in NOX emission when HHO is supplemented with biodiesel Keywords –

  8. Performance of single-cylinder compression ignition engine with indigenous castor oil bio diesel / Tek Silindirli Sıkıştırma Ateşlemeli Motorun Yöresel Hintyağı Otu Biyodizeli ile Performansı

    OpenAIRE

    Vashist, Devendra; Ahmad, Mukhtar

    2014-01-01

    Neat castor oil poses problems when used in CI engine. Problems are reduced to minimum by subjecting the castor oil to transesterification. Castor oil was converted to bio diesel and blended by 5%, 10%, 15% and 20% in quantity (by volume) with high-speed mineral diesel (HSD) fuel. This fuel was used on a single-cylinder compression-ignition, four-stroke diesel engine. The blended fuel gave lower emissions of CO but resulted in higher values of CO2...

  9. Analytical model for fast-shock ignition

    OpenAIRE

    S. A. Ghasemi; A. H. Farahbod; Sobhanian, S.

    2014-01-01

    A model and its improvements are introduced for a recently proposed approach to inertial confinement fusion, called fast-shock ignition (FSI). The analysis is based upon the gain models of fast ignition, shock ignition and considerations for the fast electrons penetration into the pre-compressed fuel to examine the formation of an effective central hot spot. Calculations of fast electrons penetration into the dense fuel show that if the initial electron kinetic energy is of the order ∼4.5 MeV...

  10. Heat wave fast ignition in inertial confinement energy

    Institute of Scientific and Technical Information of China (English)

    Shalom; Eliezer; Shirly; Vinikman; Pinhasi

    2013-01-01

    An accelerated micro-foil is used to ignite a pre-compressed cylindrical shell containing deuterium–tritium fuel.The well-known shock wave ignition criterion and a novel criterion based on heat wave ignition are developed in this work.It is shown that for heat ignition very high impact velocities are required.It is suggested that a multi-petawatt laser can accelerate a micro-foil to relativistic velocities in a very short time duration(picosecond)of the laser pulse.The cylindrical geometry suggested here for the fast ignition approach has the advantage of geometrically separating the nanosecond lasers that compress the target from the picosecond laser that accelerates the foil.The present model suggests that nuclear fusion by micro-foil impact ignition could be attained with currently existing technology.

  11. Antiproton fast ignition for inertial confinement fusion

    International Nuclear Information System (INIS)

    With 180 MJ/microg, antiprotons offer the highest stored energy per unit mass of any known entity. The use of antiprotons to promote fast ignition in an inertial confinement fusion (ICF) capsule and produce high target gains with only modest compression of the main fuel is investigated. Unlike standard fast ignition where the ignition energy is supplied by energetic, short pulse laser, the energy here is supplied through the ionization energy deposited when antiprotons annihilate at the center of a compressed fuel capsule. This can be considered in-situ fast ignition as it obviates the need for the external injection of the ignition energy. In the first of two candidate schemes, the antiproton package is delivered by a low-energy ion beam. In the second, autocatalytic scheme, the antiprotons are preemplaced at the center of the capsule prior to compression. In both schemes, the author estimates that ∼1012 antiprotons are required to initiate fast ignition in a typical ICF capsule and show that incorporation of a thin, heavy metal shell is desirable to enhance energy deposition within the ignitor zone. In addition to eliminating the need for a second, energetic fast laser and vulnerable final optics, this scheme would achieve central ignition without reliance on laser channeling through halo plasma or Hohlraum debris. However, in addition to the practical difficulties of storage and manipulation of antiprotons at low energy, the other large uncertainty for the practicality of such a speculative scheme is the ultimate efficiency of antiproton production in an external, optimized facility. Estimates suggest that the electrical wall plug energy per pulse required for the separate production of the antiprotons is of the same order as that required for the conventional slow compression driver

  12. IGNITION AND FRONTIER SCIENCE ON THE NATIONAL IGNITION FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    Moses, E

    2009-06-22

    of Inertial Fusion Energy (IFE) and will likely focus the world's attention on the possibility of an ICF energy option. NIF experiments to demonstrate ignition and gain will use central-hot-spot (CHS) ignition, where a spherical fuel capsule is simultaneously compressed and ignited. The scientific basis for CHS has been intensively developed and has high probability of success. Achieving ignition with CHS will open the door for other advanced concepts, such as the use of high-yield pulses of visible wavelength rather than ultraviolet and Fast Ignition concepts. Moreover, NIF will have important scientific applications in such diverse fields as astrophysics, nuclear physics and materials science. The NIC will develop the full set of capabilities required to operate NIF as a major national and international user facility. A solicitation for NIF frontier science experiments to be conducted by the academic community is planned for summer 2009. This paper summarizes the design, performance, and status of NIF, experimental plans for NIC, and will present a brief discussion of the unparalleled opportunities to explore frontier basic science that will be available on the NIF.

  13. Hypervelocity Impact Fusion with Compressed Deuterium-Tritium Targets

    CERN Document Server

    Olariu, S

    1998-01-01

    The neutron yields observed in inertial confinement fusion experiments for higher convergence ratios are about two orders of magnitude smaller than the neutron yields predicted by one-dimensional models, the discrepancy being attributed to the development of instabilities. We consider the possibility that ignition and a moderate gain could be achieved with existing laser facilities if the laser driver energy is used to produce only the radial compression of the fuel capsule to high densities but relatively low temperatures, while the ignition of the fusion reactions in the compressed fuel capsule will be effected by a synchronized hypervelocity impact. A positively-charged incident projectile can be accelerated to velocities of 3.5 x 10^6 m/s, resulting in ignition temperatures of about 4 keV, by a conventional low-beta linac having a length of 13 km if deuterium-tritium densities of 570 g/cm^3 could be obtained by laser-driven compression.

  14. Review of progress in Fast Ignition

    International Nuclear Information System (INIS)

    Marshall Rosenbluth's extensive contributions included seminal analysis of the physics of the laser-plasma interaction and review and advocacy of the inertial fusion program. Over the last decade he avidly followed the efforts of many scientists around the world who have studied Fast Ignition, an alternate form of inertial fusion. In this scheme, the fuel is first compressed by a conventional inertial confinement fusion driver and then ignited by a short (∼10 ps) pulse, high-power laser. Due to technological advances, such short-pulse lasers can focus power equivalent to that produced by the hydrodynamic stagnation of conventional inertial fusion capsules. This review will discuss the ignition requirements and gain curves starting from simple models and then describe how these are modified, as more detailed physics understanding is included. The critical design issues revolve around two questions: How can the compressed fuel be efficiently assembled? And how can power from the driver be delivered efficiently to the ignition region? Schemes to shorten the distance between the critical surface where the ignitor laser energy is nominally deposited and the ignition region will de discussed. The current status of Fast Ignition research is compared with our requirements for success. Future research directions will also be outlined

  15. Investigation of fusion gain in fast ignition with conical targets

    OpenAIRE

    MJ Tabatabaei; Ghasemizad, A.

    2011-01-01

    Fast ignition is a new scheme for inertial confinement fusion (ICF). In this scheme, at first the interaction of ultraintense laser beam with the hohlraum wall surrounding a capsule containing deuterium-tritium (D-T) fuel causes implosion and compression of fuel to high density and then laser produced protons penetrate in the compressed fuel and deposit their energy in it as the ignition hot spot is created. In this paper, following the energy gain of spherical target and considering relation...

  16. 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.

  17. Comportamento de um motor de ignição por compressão trabalhando com óleo Diesel e gás natural A dual fuel compression ignition engine performance, running with Diesel fuel and natural gas

    Directory of Open Access Journals (Sweden)

    José F. Schlosser

    2004-12-01

    Full Text Available A previsível escassez de petróleo aliada a uma consciência ecológica está levando pesquisadores a procurar novas fontes de energia e processos de combustão mais eficientes e menos poluentes. Entre os combustíveis menos poluentes está o gás natural, cujo consumo aumenta ano a ano. Os motores de combustão interna são transformadores de energia que têm baixa eficiência de conversão. Este trabalho avaliou um motor Diesel, bicombustível, movido a Diesel e gás natural. Nesse motor, a energia provém, basicamente, da combustão do gás natural. O Diesel tem a função de produzir o início da combustão do gás, que é o combustível principal. Assim, haverá uma substituição parcial de óleo Diesel por gás natural, aumentando o rendimento da combustão. Inicialmente, foi feito um ensaio-testemunha, somente com óleo Diesel e após foram feitos ensaios, com três repetições, para variadas proporções de óleo Diesel, gás natural e ângulos de avanço da injeção. O melhor desempenho foi obtido para 22% de óleo Diesel em relação ao máximo débito da bomba injetora e 13 L min-1 de gás natural com ângulo de avanço de injeção original (21º. Nesse caso, a potência média aumentou 14%, e o consumo específico (medido em valores monetários diminuiu 46% em relação ao ensaio-testemunha.The foresight of a petroleum shortage and an ecological conscience is moving scientists to look for new sources of energy and to develop more efficient combustion processes and reduced emissions. Natural gas is a reduced emission fuel, whose consumption increases every year. The present work evaluates a dual fuel compression ignition engine. The major portion of the fuel burned is natural gas. The Diesel fuel acts as combustion starter, which ignites under the compression heat. Diesel fuel is used only as an ignition source. The partial substitution of Diesel fuel by natural gas increases the combustion efficiency and achieves significant

  18. The Holy Grail of variable compression within piston range; Le Graal de la compression variable a portee de piston

    Energy Technology Data Exchange (ETDEWEB)

    Boncquet, P.Y.

    2004-09-01

    A new concept of variable compression engine, developed by Viannet Rhabi from the company MCE-5, allows to adapt the compression ratio of an internal combustion engine (volume between the up and down positions of the piston) to the conditions of use of the vehicle. This system uses an intermediate part between the piston and the crank-shaft which acts like a lever and allows to change the compression ration from 7:1 to 17:1 in a very reactive and precise way. The efficiency gain of this system allows to save 5 to 7% of fuel. This system opens also the way to engines down-sizing with up to 30% of fuel saving results and without the self-ignition problem linked with turbo-charged down-sized engines. Short paper. (J.S.)

  19. Fast ignition physics and its requirements to numerical simulation

    International Nuclear Information System (INIS)

    Fast ignition is a new igniting scheme for inertial confinement fusion (ICF). However, the theoretical and experimental researches show that the ignition phase of the fast ignition is very complicated and difficult. The fast ignition research needs a deep and thorough numerical simulation. Based on physical analysis, the requirements of the fast ignition for the numerical simulation are explored, and, at the same time, the problem in the light of the specific conditions of our institute is discussed. The fast ignition mainly includes three processes, those are implosive pre-compression, ultra-intense laser propagation in sub-critical and super-critical plasmas (channeling and boring), and the generation and transportation of hot electrons in plasma, especially in dense plasma, with producing the high-temperature ignition zone. The research considers that for target pre-compression, not only 1D, 2D, but also three-dimensional laser target coupling code are needed; to describe the behavior of hot electron the Fokker-Planck equation considering electric and magnetic fields is suitable, whereas the hydrodynamic motion of the plasma should be two-streaming, with the electrical and magnetic effects included. PIC code could be used to investigate the local details and supply the data needed for solving the mentioned equations. Furthermore, some countries-planed future projects for realizing the fast ignition in a concise way are still stated. (authors)

  20. Fast Electron Transport and Spatial Energy Deposition in Cu-doped Fast Ignition Plasmas

    OpenAIRE

    Jarrott, Leonard Charles

    2015-01-01

    Fast Ignition (FI) is a form of Inertial Confinement Fusion where the compression phase and the ignition phase are separated. In this scheme, a radially symmetric configuration of driver beams composed of either direct laser illumination or laser produced x-ray radiation are used to isochorically compress the fuel shell to ̃300g/cc. Once the fuel is assembled, a high-intensity ignition beam ("short pulse'') is used to generate relativistic electrons which then transport to the assembled fuel ...

  1. Direct numerical simulations of the ignition of lean primary reference fuel/air mixtures with temperature inhomogeneities

    KAUST Repository

    Luong, Minhbau

    2013-10-01

    The effects of fuel composition, thermal stratification, and turbulence on the ignition of lean homogeneous primary reference fuel (PRF)/air mixtures under the conditions of constant volume and elevated pressure are investigated by direct numerical simulations (DNSs) with a new 116-species reduced kinetic mechanism. Two-dimensional DNSs were performed in a fixed volume with a two-dimensional isotropic velocity spectrum and temperature fluctuations superimposed on the initial scalar fields with different fuel compositions to elucidate the influence of variations in the initial temperature fluctuation and turbulence intensity on the ignition of three different lean PRF/air mixtures. In general, it was found that the mean heat release rate increases slowly and the overall combustion occurs fast with increasing thermal stratification regardless of the fuel composition under elevated pressure and temperature conditions. In addition, the effect of the fuel composition on the ignition characteristics of PRF/air mixtures was found to vanish with increasing thermal stratification. Chemical explosive mode (CEM), displacement speed, and Damköhler number analyses revealed that the high degree of thermal stratification induces deflagration rather than spontaneous ignition at the reaction fronts, rendering the mean heat release rate more distributed over time subsequent to thermal runaway occurring at the highest temperature regions in the domain. These analyses also revealed that the vanishing of the fuel effect under the high degree of thermal stratification is caused by the nearly identical propagation characteristics of deflagrations of different PRF/air mixtures. It was also found that high intensity and short-timescale turbulence can effectively homogenize mixtures such that the overall ignition is apt to occur by spontaneous ignition. These results suggest that large thermal stratification leads to smooth operation of homogeneous charge compression-ignition (HCCI

  2. Ignition study of a petrol/CNG single cylinder engine

    Science.gov (United States)

    Khan, N.; Saleem, Z.; Mirza, A. A.

    2005-11-01

    Benefits of laser ignition over the electrical ignition system for Compressed Natural Gas (CNG) engines have fuelled automobile industry and led to an extensive research on basic characteristics to switch over to the emerging technologies. This study was undertaken to determine the electrical and physical characteristics of the electric spark ignition of single cylinder petrol/CNG engine to determine minimum ignition requirements and timeline of ignition events to use in subsequent laser ignition study. This communication briefly reviews the ongoing research activities and reports the results of this experimental study. The premixed petrol and CNG mixtures were tested for variation of current and voltage characteristics of the spark with speed of engine. The current magnitude of discharge circuit was found to vary linearly over a wide range of speed but the stroke to stroke fire time was found to vary nonlinearly. The DC voltage profiles were observed to fluctuate randomly during ignition process and staying constant in rest of the combustion cycle. Fire to fire peaks of current amplitudes fluctuated up to 10% of the peak values at constant speed but increased almost linearly with increase in speed. Technical barriers of laser ignition related to threshold minimum ignition energy, inter-pulse durations and firing sequence are discussed. Present findings provide a basic initiative and background information for designing suitable timeline algorithms for laser ignited leaner direct injected CNG engines.

  3. The National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Miller, G H; Moses, E I; Wuest, C R

    2004-02-06

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter-diameter target chamber and room for 100 diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion and matter at extreme energy densities and pressures. NIF's energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will study physical processes at temperatures approaching 10{sup 8} K and 10{sup 11} bar; conditions that exist naturally only in the interior of stars and planets. NIF has completed the first phases of its laser commissioning program. The first four beams of NIF have generated 106 kilojoules in 23-ns pulses of infrared light and over 16 kJ in 3.5-ns pulses at the third harmonic (351 nm). NIF's target experimental systems are being commissioned and experiments have begun. This paper provides a detailed look the NIF laser systems, laser and optical performance, and results from recent laser commissioning shots. We follow this with a discussion of NIF's high-energy-density and inertial fusion experimental capabilities, the first experiments on NIF, and plans for future capabilities of this unique facility.

  4. Study of the compression ignition engine using composite emulsified fuel. ; Engine performances and exhaust emission characteristics under operation using composite emulsified fuel of gas oil, water and methanol or ethanol. Asshuku tenka fukugo nyuka nenryo kikan ni kansuru kenkyu. ; Keiyuter dot mizuter dot alchol fukugo nyuka nenryo kyokyuji no kikan seino oyobi haiki tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Kajitani, S.; Sawa, N. (Ibaraki Univ., Ibaraki, (Japan). Faculty of Engineering)

    1990-06-25

    In the compression ignition engine, it is pointed out that gas oil/water emulsified fuel is effective in reducing the NO {sub x} as well as in enhancing the thermal efficiency and in reducing the smoke emission. Thus, the fuel injection rate, combustion, enigne performances and exhaust gas characteristics of prechamber-type compression ignition engines operated with a composite emulsified fuel made of gas oil, methanol (or ethanol) and water, were investigated; and the results were compared with those operated with gas oil or gas oil/water emulsified fuel. The fuel injection beginning time tends to advance than the setting time, with increasing in the viscosity of fuel and with increasing in the injection rate. The thermal efficiency under the composite emulsified fuel operation was found to be of the same level as that under the gas oil operation or gas oil/water emulsified fuel operation. Bosch smoke emission and the NO {sub x} under the composite emulsified fuel operation were reduced markedly (40-50% reduction) as compared with those of the gas oil operation, but they were slightly increased as compared with those of the gas oil/water emulsified fuel. The engine noise with the composite emulsified fuel operation was lower than that with the gas oil/water emulsified fuel, but was same level to that with the gas oil. 22 refs., 14 figs.

  5. Fast-shock ignition: a new approach to inertial confinement fusion

    Directory of Open Access Journals (Sweden)

    AH Farahbod

    2013-03-01

    Full Text Available  A new concept for inertial confinement fusion called fast-shock ignition (FSI is introduced as a credible scheme in order to obtain high target gain. In the proposed model, the separation of fuel ignition into two successive steps, under the suitable conditions, reduces required ignitor energy for the fuel ignition. The main procedure in FSI concept is compressing the fuel up to stagnation. Then, two high intensity short pulse laser spikes with energy and power lower than those required for shock ignition (SI and fast ignition (FI with a proper delay time are launched at the fuel which increases the central hot-spot temperature and completes the ignition of the precompressed fuel. The introduced semi-analytical model indicates that with fast-shock ignition, the total required energy for compressing and igniting the fuel can be slightly reduced in comparison to pure shock ignition. Furthermore, for fuel mass greater than , the target energy gain increases up to 15 percent and the contribution of fast ignitor under the proper conditions could be decreased about 20 percent compared with pure fast ignition. The FSI scheme is beneficial from technological considerations for the construction of short pulse high power laser drivers. The general advantages of fast-shock ignition over pure shock ignition in terms of figure of merit can be more than 1.3.

  6. Investigating antennas as ignition aid for automotive HID lamps

    International Nuclear Information System (INIS)

    This paper considers the ignition of mercury-free high-intensity discharge (HID) lamps for car headlights. Due to safety reasons, these lamps need to have a fast run-up phase which is ensured, amongst other things, by a high Xe pressure of roughly 15 bar (cold) in the discharge vessel. The high Xe pressure causes an increased ignition voltage compared with former mercury-containing automotive HID lamps or low-pressure lamps used for general-lighting applications. The increase in ignition voltage can be limited if the electric field in front of the electrodes is raised by an uplifting of the electrical conductivity along the outer wall of the inner bulb either by a conductive layer on its surface or by a dielectric barrier discharge (DBD) within the outer bulb. This paper considers on the one hand conventional antennas deposited by physical vapour deposition (PVD) and on the other hand a combination of these antennas with a DBD within the outer-bulb operated in 100 mbar Ar as ignition aids. In both cases the antenna potential and antenna width are varied. Additionally, the effects of antenna thickness and antenna material are investigated. The ignition voltage, ignition current and light emission during ignition are measured on a nanosecond timescale. Furthermore, for the very first time, the ignition process is recorded in four consecutive intensified charge-coupled device images using a high-speed camera system with a time resolution in the range of nanoseconds. It was found that antennas strongly reduce the ignition voltage of automotive HID lamps. Active antennas reduce the ignition voltage significantly more than passive antennas, proportional to the conductance of the antenna. Combining conventional antennas with an outer-bulb discharge reduces the ignition voltage from 19 kV without any ignition aid to the intrinsic ignition voltage of the lamp below 10 kV, in the best case. (paper)

  7. Reaching ignition in the tokamak

    International Nuclear Information System (INIS)

    This review covers the following areas: (1) the physics of burning plasmas, (2) plasma physics requirements for reaching ignition, (3) design studies for ignition devices, and (4) prospects for an ignition project

  8. Analytical model for fast-shock ignition

    Directory of Open Access Journals (Sweden)

    S. A. Ghasemi

    2014-07-01

    Full Text Available A model and its improvements are introduced for a recently proposed approach to inertial confinement fusion, called fast-shock ignition (FSI. The analysis is based upon the gain models of fast ignition, shock ignition and considerations for the fast electrons penetration into the pre-compressed fuel to examine the formation of an effective central hot spot. Calculations of fast electrons penetration into the dense fuel show that if the initial electron kinetic energy is of the order ∼4.5 MeV, the electrons effectively reach the central part of the fuel. To evaluate more realistically the performance of FSI approach, we have used a quasi-two temperature electron energy distribution function of Strozzi (2012 and fast ignitor energy formula of Bellei (2013 that are consistent with 3D PIC simulations for different values of fast ignitor laser wavelength and coupling efficiency. The general advantages of fast-shock ignition in comparison with the shock ignition can be estimated to be better than 1.3 and it is seen that the best results can be obtained for the fuel mass around 1.5 mg, fast ignitor laser wavelength ∼0.3  micron and the shock ignitor energy weight factor about 0.25.

  9. Particle Simulation of Fusion Ignition

    International Nuclear Information System (INIS)

    Full text: A new molecular dynamics (MD) particle simulation code has been developed to study inertial fusion ignition physics including effects of a non-Maxwellian ion velocity distribution. 10,000 DT ions at density 100 g/cc and temperatures of several keV are followed for 10 to 20 psec. The simulation includes ion-ion collisions, electron-ion coupling and emission and absorption of radiation. Fusion reactions produce energetic alphas which deposit energy to electrons and ions and the plasma self-heats to 20 — 30 keV. This simulation using realistic particles and interactions poses the scientific challenge of including quantum processes (fusion, radiation) in a classical particle simulation and the computational challenge of following the calculation for long enough to see significant plasma self-heating. The paper gives a detailed discussion of special physical and numerical techniques which make it possible to do such a simulation. The molecular dynamics is carefully compared to hydrodynamic simulations of small plasma volumes to test both codes. The most important new physics in MD simulations is the possibility to include a non-Maxwell ion velocity distribution f (υ); fusion reaction rates are very sensitive to the high-energy tail of f (υ), which depends delicately on plasma transport and equilibration processes. Although equilibrium ion-pair correlation is not strong in multi-keV plasmas we find substantial dynamical correlations caused by alpha-particle energy transfers. It is found that calculations starting from a variety of initial conditions evolve to follow a unique self-heating trajectory, an ignition attractor. Calculations starting with 3 keV DT heat to ignition within a few psec after a pulse of energetic ions are injected; this shows that fast ions are quite effective for fast ignition of precompressed DT. A series of such calculations are performed to determine the threshold ion deposition heating required to ignite DT fuel within the short

  10. Ignition probabilities for Compact Ignition Tokamak designs

    International Nuclear Information System (INIS)

    A global power balance code employing Monte Carlo techniques had been developed to study the ''probability of ignition'' and has been applied to several different configurations of the Compact Ignition Tokamak (CIT). Probability distributions for the critical physics parameters in the code were estimated using existing experimental data. This included a statistical evaluation of the uncertainty in extrapolating the energy confinement time. A substantial probability of ignition is predicted for CIT if peaked density profiles can be achieved or if one of the two higher plasma current configurations is employed. In other cases, values of the energy multiplication factor Q of order 10 are generally obtained. The Ignitor-U and ARIES designs are also examined briefly. Comparisons of our empirically based confinement assumptions with two theory-based transport models yield conflicting results. 41 refs., 11 figs

  11. Low profile thermite igniter

    Science.gov (United States)

    Halcomb, Danny L.; Mohler, Jonathan H.

    1991-03-05

    A thermite igniter/heat source comprising a housing, high-density thermite, and low-density thermite. The housing has a relatively low profile and can focus energy by means of a torch-like ejection of hot reaction products and is externally ignitable.

  12. Ignition Regime and Burn Dynamics of DT-Seeded D3He Fuel for Fast Ignition Inertial Confinement Fusion

    International Nuclear Information System (INIS)

    Full text: The feasibility of igniting D3He fuel in the fast-ignition inertial confinement fusion is examined by appropriately treating the plasma heating processes by fusion-produced fast particles. Simulations have been made for a DT/D-3He pellet compressed to 2000 - 5000 times the liquid density. Newly included is the transport of recoil ions generated by knock-on collisions of D-T neutrons and D-3He protons. Although the ignition condition is degraded by inclusion of the recoil-ion transport, it is still possible to obtain sufficient pellet gains (> 60) with realistic driver energy below 10 MJ. (author)

  13. Ignition tuning for the National Ignition Campaign

    Directory of Open Access Journals (Sweden)

    Landen O.

    2013-11-01

    Full Text Available The overall goal of the indirect-drive inertial confinement fusion [1] tuning campaigns [2] is to maximize the probability of ignition by experimentally correcting for likely residual uncertainties in the implosion and hohlraum physics [3] used in our radiation-hydrodynamic computational models, and by checking for and resolving unexpected shot-to-shot variability in performance [4]. This has been started successfully using a variety of surrogate capsules that set key laser, hohlraum and capsule parameters to maximize ignition capsule implosion velocity, while minimizing fuel adiabat, core shape asymmetry and ablator-fuel mix.

  14. Fast-shock ignition: a new approach to inertial confinement fusion

    OpenAIRE

    AH Farahbod; SA Ghasemi

    2013-01-01

     A new concept for inertial confinement fusion called fast-shock ignition (FSI) is introduced as a credible scheme in order to obtain high target gain. In the proposed model, the separation of fuel ignition into two successive steps, under the suitable conditions, reduces required ignitor energy for the fuel ignition. The main procedure in FSI concept is compressing the fuel up to stagnation. Then, two high intensity short pulse laser spikes with energy and power lower than those required for...

  15. Neutron, electron and photon transport in ICF tragets in direct and fast ignition

    OpenAIRE

    A. Parvazian; A. Okhovat

    2005-01-01

    Fusion energy due to inertial confinement has progressed in the last few decades. In order to increase energy efficiency in this method various designs have been presented. The standard scheme for direct ignition and fast ignition fuel targets are considered. Neutrons, electrons and photons transport in targets containing different combinations of Li and Be are calculated in both direct and fast ignition schemes. To compress spherical multilayer targets having fuel in the central part, they a...

  16. Studies on Exhaust Emissions from Copper-Coated Gasohol Run Spark Ignition Engine with Catalytic Converter

    OpenAIRE

    S. Narasimha Kumar*1; Kishor, K.; M.V.S. Murali Krishna; P.V.K.Murthy

    2011-01-01

    The major pollutants emitted from spark ignition engine are carbon monooxide (CO) and unburnt hydrocarbons (UHC). These are hazardous and cause health problems to human beings, and hence control of these pollutants calls for immediate attention. Copper of thickness 300 microns is coated over piston crown and inside portion of the cylinder head of the spark ignition engine. Investigations have been carried out for reducing pollutants from a variable compression ratio, copper-coated spark ignit...

  17. 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

  18. Acoustic Igniter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...

  19. National Ignition Facility design focuses on optics

    International Nuclear Information System (INIS)

    Sometime in the year 2002, scientists at the National Ignition Facility (NIF) will focus 192 separate high-power ultraviolet laser beams onto a tiny capsule of deuterium and tritium, heating and compressing the material until it ignites and burns with a burst of fusion energy. The mission of NIF, which will contain the largest laser in the world, is to obtain fusion ignition and gain and to use inertial confinement fusion capabilities in nuclear weapons science experiments. The physics data provided by NIF experiments will help scientists ensure nuclear weapons reliability without the need for actual weapons tests; basic sciences such as astrophysics will also benefit. The facility faces stringent weapons-physics user requirements demanding peak pulse powers greater than 750 TW at 0.35 microm (only 500 TW is required for target ignition), pulse durations of 0.1 to 20 ns, beam steering on the order of several degrees, and target isolation from residual 1- and 0.5-microm radiation. Additional requirements include 50% fractional encircled beam energy in a 100-microm-diameter spot, with 95% encircled in a 200-microm spot. The weapons-effects community requires 1- and 0.5-microm light on target, beam steering to widely spaced targets, a target chamber accommodating oversized objects, well-shielded diagnostic areas, and elimination of stray light in the target chamber. The beamline design, amplifier configuration and requirements for optics are discussed here

  20. Implosion and burn of fast ignition capsules—Calculations with HYDRA

    International Nuclear Information System (INIS)

    We present a methodology for conducting the design calculations for fast ignition indirect-drive implosions with an embedded cone for introducing a second laser beam to ignite the compressed fuel. These calculations are tuned to achieve several design goals. We demonstrate a major feature of the implosion simulations, the lagging of the implosions along the cone. Possible avenues for enhancing the coupling of the fast electrons to the dense compressed DT fuel are discussed.

  1. Implosion and burn of fast ignition capsules-Calculations with HYDRA

    Energy Technology Data Exchange (ETDEWEB)

    Shay, H. D.; Amendt, P.; Clark, D.; Ho, D.; Key, M.; Koning, J.; Marinak, M.; Strozzi, D.; Tabak, M. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94551 (United States)

    2012-09-15

    We present a methodology for conducting the design calculations for fast ignition indirect-drive implosions with an embedded cone for introducing a second laser beam to ignite the compressed fuel. These calculations are tuned to achieve several design goals. We demonstrate a major feature of the implosion simulations, the lagging of the implosions along the cone. Possible avenues for enhancing the coupling of the fast electrons to the dense compressed DT fuel are discussed.

  2. Fusion ignition via a magnetically-assisted fast ignition approach

    CERN Document Server

    Wang, W -M; Sheng, Z -M; Li, Y T; Zhang, J

    2016-01-01

    Significant progress has been made towards laser-driven fusion ignition via different schemes, including direct and indirect central ignition, fast ignition, shock ignition, and impact ignition schemes. However, to reach ignition conditions, there are still various technical and physical challenges to be solved for all these schemes. Here, our multi-dimensional integrated simulation shows that the fast-ignition conditions could be achieved when two 2.8 petawatt heating laser pulses counter-propagate along a 3.5 kilotesla external magnetic field. Within a period of 5 picoseconds, the laser pulses heat a nuclear fuel to reach the ignition conditions. Furthermore, we present the parameter windows of lasers and magnetic fields required for ignition for experimental test.

  3. Innovative ICF scheme-impact fast ignition

    International Nuclear Information System (INIS)

    A totally new ignition scheme for ICF, impact fast ignition (IFI), is proposed [1], in which the compressed DT main fuel is to be ignited by impact collision of another fraction of separately imploded DT fuel, which is accelerated in the hollow conical target. Two-dimensional hydrodynamic simulation results in full geometry are presented, in which some key physical parameters for the impact shell dynamics such as 108 cm/s of the implosion velocity, 200- 300 g/cm3 of the compressed density, and the converted temperature beyond 5 keV are demonstrated. As the first step toward the proof-of-principle of IFI, we have conducted preliminary experiments under the operation of GEKKO XII/HYPER laser system to achieve a hyper-velocity of the order of 108 cm/s. As a result we have observed a highest velocity, 6.5 x 107 cm/s, ever achieved. Furthermore, we have also done the first integrated experiments using the target and observed substantial amount of neutron yields. Reference: [1] M. Murakami and Nagatomo, Nucl. Instrum. Meth. Phys. Res. A 544(2005) 67

  4. Ignition tuning for the National Ignition Campaign

    OpenAIRE

    Landen O.; Edwards J; Haan S. W.; Lindl J.D.; Boehly T.R.; Bradley D.K.; Callahan D.A.; Celliers P.M.; Dewald E.L.; Dixit S.; Doeppner T.; Eggert J.; Farley D.; Frenje J.A.; Glenn S.

    2013-01-01

    The overall goal of the indirect-drive inertial confinement fusion [1] tuning campaigns [2] is to maximize the probability of ignition by experimentally correcting for likely residual uncertainties in the implosion and hohlraum physics [3] used in our radiation-hydrodynamic computational models, and by checking for and resolving unexpected shot-to-shot variability in performance [4]. This has been started successfully using a variety of surrogate capsules that set key laser, hohlraum and caps...

  5. Study of the shock ignition scheme in inertial confinement fusion

    International Nuclear Information System (INIS)

    The Shock Ignition (SI) scheme is an alternative to classical ignition schemes in Inertial Confinement Fusion. Its singularity relies on the relaxation of constraints during the compression phase and fulfilment of ignition conditions by launching a short and intense laser pulse (∼500 ps, ∼300 TW) on the pre-assembled fuel at the end of the implosion.In this thesis, it has been established that the SI process leads to a non-isobaric fuel configuration at the ignition time thus modifying the ignition criteria of Deuterium-Tritium (DT) against the conventional schemes. A gain model has been developed and gain curves have been inferred and numerically validated. This hydrodynamical modeling has demonstrated that the SI process allows higher gain and lower ignition energy threshold than conventional ignition due to the high hot spot pressure at ignition time resulting from the ignitor shock propagation.The radiative hydrodynamic CHIC code developed at the CELIA laboratory has been used to determine parametric dependences describing the optimal conditions for target design leading to ignition. These numerical studies have enlightened the potential of SI with regards to saving up laser energy, obtain high gains but also to safety margins and ignition robustness.Finally, the results of the first SI experiments performed in spherical geometry on the OMEGA laser facility (NY, USA) are presented. An interpretation of the experimental data is proposed from mono and bidimensional hydrodynamic simulations. Then, different trails are explored to account for the differences observed between experimental and numerical data and alternative solutions to improve performances are suggested. (author)

  6. Fast ignition: Dependence of the ignition energy on source and target parameters for particle-in-cell-modelled energy and angular distributions of the fast electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bellei, C.; Divol, L.; Kemp, A. J.; Key, M. H.; Larson, D. J.; Strozzi, D. J.; Marinak, M. M.; Tabak, M.; Patel, P. K. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

    2013-05-15

    The energy and angular distributions of the fast electrons predicted by particle-in-cell (PIC) simulations differ from those historically assumed in ignition designs of the fast ignition scheme. Using a particular 3D PIC calculation, we show how the ignition energy varies as a function of source-fuel distance, source size, and density of the pre-compressed fuel. The large divergence of the electron beam implies that the ignition energy scales with density more weakly than the ρ{sup −2} scaling for an idealized beam [S. Atzeni, Phys. Plasmas 6, 3316 (1999)], for any realistic source that is at some distance from the dense deuterium-tritium fuel. Due to the strong dependence of ignition energy with source-fuel distance, the use of magnetic or electric fields seems essential for the purpose of decreasing the ignition energy.

  7. Ion beam requirements for fast ignition of inertial fusion targets

    CERN Document Server

    Honrubia, J J

    2015-01-01

    Ion beam requirements for fast ignition are investigated by numerical simulation taking into account new effects such as ion beam divergence not included before. We assume that ions are generated by the TNSA scheme in a curved foil placed inside a re-entrant cone and focused on the cone apex or beyond. From the focusing point to the compressed core ions propagate with a given divergence angle. Ignition energies are obtained for two compressed fuel configurations heated by proton and carbon ion beams. The dependence of the ignition energies on the beam divergence angle and on the position of the ion beam focusing point have been analysed. Comparison between TNSA and quasi-monoenergetic ions is also shown.

  8. Numerical analysis of knock during HCCI in a high compression ratio methanol engine based on LES with detailed chemical kinetics

    International Nuclear Information System (INIS)

    Highlights: • Knock during HCCI in a high compression ratio methanol engine was modeled. • A detailed methanol mechanism was used to simulate the knocking combustion. • Compared with the SI engines, the HCCI knocking combustion burnt faster. • The reaction rate of HCO had two obvious peaks, one was positive, and another was negative. • Compared with the SI engines, the values of the reaction rates of CH2O, H2O2, and HO2 were higher, and it had negative peaks. - Abstract: In this study, knock during HCCI (homogeneous charge compression ignition) was studied based on LES (large eddy simulation) with methanol chemical kinetics (84-reaction, 21-species) in a high compression ratio methanol engine. The non-knocking and knocking combustion of SI (spark ignition) and HCCI engines were compared. The results showed that the auto-ignition spots were initially occurred near the combustion chamber wall. The knocking combustion burnt faster during HCCI than SI methanol engine. The HCO reaction rate was different from SI engine, it had two obvious peaks, one was positive peak, and another was negative peak. Compared with the SI methanol engine, in addition to the concentration of HCO, the concentrations of the other intermediate products and species such as CO, OH, CH2O, H2O2, HO2 were increased significantly; the reaction rates of CH2O, H2O2, and HO2 had negative peaks, and whose values were several times higher than SI methanol engine

  9. Laser-plasma interactions for fast ignition

    CERN Document Server

    Kemp, A J; Debayle, A; Johzaki, T; Mori, W B; Patel, P K; Sentoku, Y; Silva, L O

    2013-01-01

    In the electron-driven fast-ignition approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser plasma interactions (LPI) relevant to fast ignition. Increases in computational and modeling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multi-dimensional particle-in-cell (PIC) simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of laser absorption fraction, the laser-generated electron spectra, divergence, and their temporal evolution. Scaling with irradiation conditions such as laser intensity are considered, as well as the dependence on plasma parameters. Different numerical modeling approaches and configurations are addressed, providing an overview of the modeling capabilities and limitations. In addition, we discuss the compa...

  10. Adiabatic Compression of Oxygen: Real Fluid Temperatures

    Science.gov (United States)

    Barragan, Michelle; Wilson, D. Bruce; Stoltzfus, Joel M.

    2000-01-01

    The adiabatic compression of oxygen has been identified as an ignition source for systems operating in enriched oxygen atmospheres. Current practice is to evaluate the temperature rise on compression by treating oxygen as an ideal gas with constant heat capacity. This paper establishes the appropriate thermodynamic analysis for the common occurrence of adiabatic compression of oxygen and in the process defines a satisfactory equation of state (EOS) for oxygen. It uses that EOS to model adiabatic compression as isentropic compression and calculates final temperatures for this system using current approaches for comparison.

  11. The case for fast ignition as an IFE concept exploration program

    International Nuclear Information System (INIS)

    The fast ignition (FI) concept is a variant of inertial fusion in which the compression and ignition steps are separated. Calculations suggest this would allow a substantial improvement in target gain, and could form the basis of a very attractive power plant. Transporting the energy to ignite a target involves the physics of light-driven relativistic plasmas; a subject which is not well understood. A concept exploration effort to understand the energy transport physics, and also to clarify the merits of a FI IFE power plant could justify a proof-of-principle program on the National Ignition Facility

  12. Observation of strong electromagnetic fields around laser-entrance holes of ignition-scale hohlraums in inertial-confinement fusion experiments at the National Ignition Facility

    International Nuclear Information System (INIS)

    Energy spectra and spectrally resolved one-dimensional fluence images of self-emitted charged-fusion products (14.7 MeV D3He protons) are routinely measured from indirectly driven inertial-confinement fusion (ICF) experiments utilizing ignition-scaled hohlraums at the National Ignition Facility (NIF). A striking and consistent feature of these images is that the fluence of protons leaving the ICF target in the direction of the hohlraum's laser entrance holes (LEHs) is very nonuniform spatially, in contrast to the very uniform fluence of protons leaving through the hohlraum equator. In addition, the measured nonuniformities are unpredictable, and vary greatly from shot to shot. These observations were made separately at the times of shock flash and of compression burn, indicating that the asymmetry persists even at ∼0.5–2.5 ns after the laser has turned off. These phenomena have also been observed in experiments on the OMEGA laser facility with energy-scaled hohlraums, suggesting that the underlying physics is similar. Comprehensive data sets provide compelling evidence that the nonuniformities result from proton deflections due to strong spontaneous electromagnetic fields around the hohlraum LEHs. Although it has not yet been possible to uniquely determine whether the fields are magnetic (B) or electric (E), preliminary analysis indicates that the strength is ∼1 MG if B fields or ∼109 V cm−1 if E fields. These measurements provide important physics insight into the ongoing ignition experiments at the NIF. Understanding the generation, evolution, interaction and dissipation of the self-generated fields may help to answer many physics questions, such as why the electron temperatures measured in the LEH region are anomalously large, and may help to validate hydrodynamic models of plasma dynamics prior to plasma stagnation in the center of the hohlraum. (paper)

  13. Gasifier burner ignition system

    Energy Technology Data Exchange (ETDEWEB)

    1979-10-01

    The BI-GAS pilot plant is designed such that its lower region (Stage I) is the combustion zone where oxygen and steam contact and react with recycled char. As with other combustion systems, provisions must be made to initiate combustion at start-up, to reinitiate combustion in case of a process upset where combustion is lost, and to continuously monitor the presence of combustion. An ignition system had to be developed, capable of reliable and repeated operation at pressures up to 1500 psi in a methane-rich or otherwise reducing atmosphere. The initial development work was done by Babcock and Wilcox and included development of both the ignitor system and the flame confirmation system. B and W's initial proposal specifically dealt with investigating a hypergolic (chemical auto-combustion) igniter. Hypergolic ignition is the spontaneous combustion of a compound upon contact with an oxygen containing media. This oxygen source includes air, oxygen, carbon dioxide, and water. The liquid compound studied was triethylaluminum (Al(C/sub 2/H/sub 5/)/sub 3/) otherwise identified as TEA and supplied by Ethyl Corporation, Baton Rouge, Louisiana. The hypergolic ignition system has been operated successfully and proved reliable at high pressure (750 psig) through repeated testing over a three-year period. The system designed by Stearns-Roger based on the study by Babcock and Wilcox was basically correct. Two relatively minor design defects and operational revisions to improve performance were accomplished by on-site personnel with little expenditure of time or money. The remaining problems currently experienced with the TEA ignition system are considered minor. Further work should continue to determine the lowest possible TEA concentration that can be used and still provide consistent ignition, and the system should be tested soon at the full design operating pressure of 1500 psig.

  14. Ignition Studies on Aluminised Propellant.

    Directory of Open Access Journals (Sweden)

    K. A. Bhaskaran

    1996-12-01

    Full Text Available An experimental investigation on the ignition of metallised propellants (APIHTPB/AI has been carried out 10 determine the ignition delay, minimum ignition energy and corresponding heat flux,threshold heat flux for ignition and minimum ignition temperature, Ignition experiments were conductedusing a shock tube under convectiveheating conditions similar to those prevailingin a rocket motor. Heat flux at propellant location was measured by thin film heat flux gauge and also calculated from a ribbon thermocouple output under similar test conditions. The igntion delay was measured as the time lag between the arrival of hot gas at the propellant and the light emission due to actual ignition of the propellant. The experimental results indicate that the ignition delay characteristics are independent of pressure. The minimum energy for ignition obtained for the propellant is 1100J/m2 corresponding to the heat flux range of 80·120 WIcm2 for a gas velocity of 110 mls. The threshold heat flux required to ignite the propellant was 40 W/cm2 at a velocity of 110 mls. Heat flux corresponding to minimum ignition energy and the threshold heat flux increase with gas velocity. The threshold ignition temperature of the propellant was found to be 600 ± 20 K.

  15. Impact ignition as a track to laser fusion

    Science.gov (United States)

    Murakami, M.; Nagatomo, H.; Johzaki, T.; Sakaiya, T.; Velikovich, A.; Karasik, M.; Gus'kov, S.; Zmitrenko, N.

    2014-05-01

    In impact ignition, the compressed deuterium-tritium main fuel is ignited by impact with a separately imploded portion of fuel, which is accelerated in a hollow conical target to hyperspeeds of the order of 1000 km s-1. Its kinetic energy is directly converted into thermal energy corresponding to an ignition temperature of about 5 keV upon collision with the compressed fuel. The ignitor shell is irradiated by nanosecond pulses at intensities of between 1015 and 1016 W cm-2 with a wavelength of 0.25-0.35 µm, resulting in ablation pressures of several hundred mega-bars. Hydrodynamics-dominated physics and avoidance of ultra-intense petawatt lasers are notable features of this scheme. Experimental results for velocities exceeding 1000 km s-1, ion temperatures up to 3 keV, and neutron yield increases of 100-fold due to the impact effect indicate the potential of impact ignition for fusion energy production. The overall performance of impact ignition is reviewed with new analyses on the neutron yield and shell acceleration.

  16. Ignition on the National Ignition Facility: a path towards inertial fusion energy

    Science.gov (United States)

    Moses, Edward I.

    2009-10-01

    the world's attention on the possibility of an ICF energy option. NIF experiments to demonstrate ignition and gain will use central-hot-spot (CHS) ignition, where a spherical fuel capsule is simultaneously compressed and ignited. The scientific basis for CHS has been intensively developed (Lindl 1998 Inertial Confinement Fusion: the Quest for Ignition and Energy Gain Using Indirect Drive (New York: American Institute of Physics)) and has a high probability of success. Achieving ignition with CHS will open the door for other advanced concepts, such as the use of high-yield pulses of visible wavelength rather than ultraviolet and fast ignition concepts (Tabak et al 1994 Phys. Plasmas 1 1626-34, Tabak et al 2005 Phys. Plasmas 12 057305). Moreover, NIF will have important scientific applications in such diverse fields as astrophysics, nuclear physics and materials science. This paper summarizes the design, performance and status of NIF, experimental plans for NIC, and will present laser inertial confinement fusion-fission energy (LIFE) as a path to achieve carbon-free sustainable energy.

  17. Ignition on the National Ignition Facility: a path towards inertial fusion energy

    International Nuclear Information System (INIS)

    the world's attention on the possibility of an ICF energy option. NIF experiments to demonstrate ignition and gain will use central-hot-spot (CHS) ignition, where a spherical fuel capsule is simultaneously compressed and ignited. The scientific basis for CHS has been intensively developed (Lindl 1998 Inertial Confinement Fusion: the Quest for Ignition and Energy Gain Using Indirect Drive (New York: American Institute of Physics)) and has a high probability of success. Achieving ignition with CHS will open the door for other advanced concepts, such as the use of high-yield pulses of visible wavelength rather than ultraviolet and fast ignition concepts (Tabak et al 1994 Phys. Plasmas 1 1626-34, Tabak et al 2005 Phys. Plasmas 12 057305). Moreover, NIF will have important scientific applications in such diverse fields as astrophysics, nuclear physics and materials science. This paper summarizes the design, performance and status of NIF, experimental plans for NIC, and will present laser inertial confinement fusion-fission energy (LIFE) as a path to achieve carbon-free sustainable energy.

  18. Nd:YAG breech mounted laser igniter

    Science.gov (United States)

    Hardy, Christopher R.; Myers, Michael J.; Myers, John D.; Gadson, Robert L.; Leone, Joseph; Fay, Josiah W.; Boyd, Kevin

    2005-09-01

    Nd:YAG lasers have been successfully used to demonstrate laser ignition of howitzer propellant charges including bag, stick, and the Modular Artillery Charge System (MACS). Breech Mount Laser Ignition Systems (BMLIS) have been designed, installed and tested on many artillery systems, including the US Army's M109A6 Paladin, M198, M777 Light Weight, Crusader, and Non-Line-of-Sight Cannon (NLOS-C). The NLOS-C incorporates advanced weapon technologies, to include a BMLIS. United Defense's Armament Systems Division has recently designed and built a NLOS-C System Demonstrator that uses a BMLIS that incorporates Kigre's patented square pulse technology. NLOS-C is one of the weapon systems being developed for use with the US Army's "systems of systems" Future Combat System (FCS), Manned Ground Vehicles (MGV) program, and is currently undergoing development testing at Yuma Proving Grounds. In this paper we discuss many technical aspects of an artillery laser ignition system and present BMLIS test data obtained from actual gun firings conducted with a number of different US Army howitzer platforms.

  19. Low temperature oxidation, co-oxidation and auto-ignition of olefinic and aromatic blending compounds: Experimental study of interactions during the oxidation of a surrogate fuel; Oxydation, co-oxydation et auto-inflammation a basses temperatures d'alcenes et aromatiques types: etude experimentale des interactions au sein d'un carburant-modele

    Energy Technology Data Exchange (ETDEWEB)

    Vanhove, G.

    2004-12-15

    The low-temperature (600-900 K) and high-pressure (5-25 bar) oxidation and auto-ignition of the three position isomers of hexene, of binary mixtures of 1-hexene, toluene and iso-octane, and of a surrogate fuel composed of these three compounds were studied in motor conditions using a rapid compression machine. Auto-ignition delay times were measured as long as intermediate products concentrations during the delay. The results show that the oxidation chemistry of the hexenes is very dependent on the position of the double bond inside the molecule, and that strong interactions between the oxidation mechanisms of hydrocarbons in mixtures can occur. The data obtained concerning the surrogate fuel give a good insight into the behaviour of a practical gasoline after an homogeneous charge compression. (author)

  20. Acceleration technology and power plant design for fast ignition heavy ion inertial fusion energy

    International Nuclear Information System (INIS)

    Full text: This talk gives an update on the progress in Heavy Ion Beam IFE experimental and theoretical activities conducted under the auspices of the Ministry of Atomic Energy of Russian Federation under contract No. 6.25.19.19.03/996. The considerations of heavy ion fusion power plant concept are based on the fast ignition principle for fusion targets. The cylindrical target is irradiated subsequently by a hollow beam in compression phase and by powerful ignition beam for initiation of the burning phase. The ignition is provided by the high energy 100 GeV Pt ions of different masses accelerated in RF-linac. The efficiency of the driver is taken ∼25%. The main beam delivers ∼5 MJ energy and the ignition beam ∼0.4 MJ to the target. Cylindrical DT filled target provides ∼600 MJ fusion yield, of which 180 MJ appears in X-rays and ionized debris and 420 MJ in neutrons. The repetition rate is taken as 2 Hz per reactor chamber. The first wall of the reactor chamber employs 'liquid wall' approach, particularly the wetted porous design. The lithium-lead eutectic is used as a coolant, with initial surface temperature of 550 deg. C. Computation of neutronics results in blanket energy deposition with maximum density of the order of 10E8 J/m3. The heat conversion system consisting of three coolant loops provides the net efficiency of the power plant of ∼35%. The Heavy Ion IFE experimental program is focused on a major upgrade of the ITEP accelerator complex for acceleration and accumulation of high current beams - the TeraWatt Accumulator project (ITEP-TWAC). Commissioning of the whole acceleration/accumulation beam gymnastic scheme with stacking of ∼10E10 C6+ and fast extraction to the experimental area has been done in 2003. The ion bunch is being compressed from 1 mks to ∼ 170 ns and focused down to a spot ∼ 1 mm. Current experiment efforts are aiming at measurements of ionization degree, charge state distribution, conductivity, plasma pressure, ion and

  1. Theory of Fast Electron Transport for Fast Ignition

    OpenAIRE

    Robinson, A. P. L.; Strozzi, D. J.; Davies, J.R.; Gremillet, L.; Honrubia, J. J.; Johzaki, T.; Kingham, R. J.; Sherlock, M.; Solodov, A. A.

    2013-01-01

    Fast Ignition Inertial Confinement Fusion is a variant of inertial fusion in which DT fuel is first compressed to high density and then ignited by a relativistic electron beam generated by a fast (< 20 ps) ultra-intense laser pulse, which is usually brought in to the dense plasma via the inclusion of a re-entrant cone. The transport of this beam from the cone apex into the dense fuel is a critical part of this scheme, as it can strongly influence the overall energetics. Here we review progres...

  2. Simulations of electron transport for fast ignition using Lisp

    International Nuclear Information System (INIS)

    A crucial issue for the viability of the fast ignition approach to inertial fusion energy is the transport of the ignition pulse energy from the critical surface to the high-density compressed fuel. Experiments have characterized this transport through the interaction of short pulse, high intensity lasers with solid-density targets containing thin Kα fluorescence layers. These experiments show a reasonably well-collimated beam, although with a significantly larger radius than the incident laser beam. We report on LSP calculations of these experiments, which show reasonable agreement with the experimental observations

  3. Plasma engineering assessments of compact ignition experiments

    International Nuclear Information System (INIS)

    Confinement, startup sequences, and fast-alpha particle effects are assessed for a class of compact tokamak ignition experiments having high toroidal magnetic fields (8 to 12 T) and high toroidal currents (7 to 10 MA). The uncertainties in confinement scaling are spanned through examples of performance with an optimistic model based on ohmically heated plasmas and a pessimistic model that includes confinement degradation by both auxiliary and alpha heating. The roles of neoclassical resistivity enhancement and sawtooth behavior are also evaluated. Copper toroidal field coils place restrictions on pulse lengths due to resistive heating, so a simultaneous rampup of the toroidal field and plasma current is proposed as a means of compressing the startup phase and lengthening the burn phase. If the ignition window is small, fast-alpha particle physics is restricted to the high-density regime where a short slowing-down time leads to low fast-particle density and pressure contributions. Under more optimistic confinement, a larger ignition margin broadens the range of alpha particle physics that can be addressed. These issues are illustrated through examples of transport simulations for a set of machine parameters called BRAND-X, which typify the designs under study

  4. Diagnostics for fast ignition science (invited).

    Science.gov (United States)

    MacPhee, A G; Akli, K U; Beg, F N; Chen, C D; Chen, H; Clarke, R; Hey, D S; Freeman, R R; Kemp, A J; Key, M H; King, J A; Le Pape, S; Link, A; Ma, T Y; Nakamura, H; Offermann, D T; Ovchinnikov, V M; Patel, P K; Phillips, T W; Stephens, R B; Town, R; Tsui, Y Y; Wei, M S; Van Woerkom, L D; Mackinnon, A J

    2008-10-01

    The ignition concept for electron fast ignition inertial confinement fusion requires sufficient energy be transferred from an approximately 20 ps laser pulse to the compressed fuel via approximately MeV electrons. We have assembled a suite of diagnostics to characterize such transfer, simultaneously fielding absolutely calibrated extreme ultraviolet multilayer imagers at 68 and 256 eV; spherically bent crystal imagers at 4.5 and 8 keV; multi-keV crystal spectrometers; MeV x-ray bremmstrahlung, electron and proton spectrometers (along the same line of sight), and a picosecond optical probe interferometer. These diagnostics allow careful measurement of energy transport and deposition during and following the laser-plasma interactions at extremely high intensities in both planar and conical targets. Together with accurate on-shot laser focal spot and prepulse characterization, these measurements are yielding new insights into energy coupling and are providing critical data for validating numerical particle-in-cell (PIC) and hybrid PIC simulation codes in an area crucial for fast ignition and other applications. Novel aspects of these diagnostics and how they are combined to extract quantitative data on ultrahigh intensity laser-plasma interactions are discussed. PMID:19044615

  5. Stable transport in proton driven Fast Ignition

    CERN Document Server

    Bret, A

    2009-01-01

    Proton beam transport in the context of proton driven Fast Ignition is usually assumed to be stable due to protons high inertia, but an analytical analysis of the process is still lacking. The stability of a charge and current neutralized proton beam passing through a plasma is therefore conducted here, for typical proton driven Fast Ignition parameters. In the cold regime, two fast growing Buneman-like modes are found, with an inverse growth-rate much smaller than the beam time-of-flight to the target core. The stability issue is thus not so obvious, and Kinetic effects are investigated. One unstable mode is found stabilized by the background plasma protons and electrons temperatures. The second mode is also damped, providing the proton beam thermal spread is larger than $\\sim$ 10 keV. In Fusion conditions, the beam propagation should therefore be stable.

  6. Catalytic ignition of light hydrocarbons

    Institute of Scientific and Technical Information of China (English)

    K. L. Hohn; C.-C. Huang; C. Cao

    2009-01-01

    Catalytic ignition refers to phenomenon where sufficient energy is released from a catalytic reaction to maintain further reaction without additional extemai heating. This phenomenon is important in the development of catalytic combustion and catalytic partial oxidation processes, both of which have received extensive attention in recent years. In addition, catalytic ignition studies provide experimental data which can be used to test theoretical hydrocarbon oxidation models. For these reasons, catalytic ignition has been frequently studied. This review summarizes the experimental methods used to study catalytic ignition of light hydrocarbons and describes the experimental and theoretical results obtained related to catalytic ignition. The role of catalyst metal, fuel and fuel concentration, and catalyst state in catalytic ignition are examined, and some conclusions are drawn on the mechanism of catalytic ignition.

  7. Fast ignition driven by quasi-monoenergetic ions: Optimal ion type and reduction of ignition energies with an ion beam array

    CERN Document Server

    Honrubia, J J; Hegelich, B M; Murakami, M; Enriquez, C D

    2014-01-01

    Fast ignition of inertial fusion targets driven by quasi-monoenergetic ion beams is investigated by means of numerical simulations. Light and intermediate ions such as lithium, carbon, aluminium and vanadium have been considered. Simulations show that the minimum ignition energies of an ideal configuration of compressed Deuterium-Tritium are almost independent on the ion atomic number. However, they are obtained for increasing ion energies, which scale, approximately, as Z^2, where Z is the ion atomic number. Assuming that the ion beam can be focused into 10 {\\mu}m spots, a new irradiation scheme is proposed to reduce the ignition energies. The combination of intermediate Z ions, such as 5.5 GeV vanadium, and the new irradiation scheme allows a reduction of the number of ions required for ignition by, roughly, three orders of magnitude when compared with the standard proton fast ignition scheme.

  8. Devices to improve the performance of a conventional two-stroke spark ignition engine

    Energy Technology Data Exchange (ETDEWEB)

    Poola, R.B. [Argonne National Lab., IL (United States); Nagalingam, B.; Gopalakrishnan, K.V. [Indian Inst. of Tech., Madras (India)

    1995-06-01

    This paper presents research efforts made in three different phases with the objective of improving the fuel economy of and reducing exhaust emissions from conventional, carbureted, two-stroke spark ignition (SI) engines, which are widely employed in two-wheel transportation in India. A review concerning the existing two-stroke engine technology for this application is included. In the first phase, a new scavenging system was developed and tested to reduce the loss of fresh charge through the exhaust port. In die second phase, the following measures were carried out to improve the combustion process: (1) using an in-cylinder catalyst, such as copper, chromium, and nickel, in the form of coating; (2) providing moderate thermal insulation in the combustion chamber, either by depositing thin ceramic material or by metal inserts; (3) developing a high-energy ignition system; and (4) employing high-octane fuel, such as methanol, ethanol, eucalyptus oil, and orange oil, as a blending agent with gasoline. Based on the effectiveness of the above measures, an optimized design was developed in the final phase to achieve improved performance. Test results indicate that with an optimized two-stroke SI engine, the maximum percentage improvement in brake thermal efficiency is about 31%, together with a reduction of 3400 ppm in hydrocarbons (HC) and 3% by volume of carbon monoxide (CO) emissions over the normal engine (at 3 kW, 3000 rpm). Higher cylinder peak pressures (3-5 bar), lower ignition delay (2-4{degrees}CA){degrees} and shorter combustion duration (4-10 {degrees}CA) are obtained. The knock-limited power output is also enhanced by 12.7% at a high compression ratio (CR) of 9:1. The proposed modifications in the optimized design are simple, low-cost and easy to adopt for both production and existing engines.

  9. Monolithic catalytic igniters

    Science.gov (United States)

    La Ferla, R.; Tuffias, R. H.; Jang, Q.

    1993-01-01

    Catalytic igniters offer the potential for excellent reliability and simplicity for use with the diergolic bipropellant oxygen/hydrogen as well as with the monopropellant hydrazine. State-of-the-art catalyst beds - noble metal/granular pellet carriers - currently used in hydrazine engines are limited by carrier stability, which limits the hot-fire temperature, and by poor thermal response due to the large thermal mass. Moreover, questions remain with regard to longevity and reliability of these catalysts. In this work, Ultramet investigated the feasibility of fabricating monolithic catalyst beds that overcome the limitations of current catalytic igniters via a combination of chemical vapor deposition (CVD) iridium coatings and chemical vapor infiltration (CVI) refractory ceramic foams. It was found that under all flow conditions and O2:H2 mass ratios tested, a high surface area monolithic bed outperformed a Shell 405 bed. Additionally, it was found that monolithic catalytic igniters, specifically porous ceramic foams fabricated by CVD/CVI processing, can be fabricated whose catalytic performance is better than Shell 405 and with significantly lower flow restriction, from materials that can operate at 2000 C or higher.

  10. Ignition target design for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Haan, S.W.; Pollaine, S.M.; Lindl, J.D. [Los Alamos National Laboratory, NM (United States)] [and others

    1996-06-01

    The goal of inertial confinement fusion (ICF) is to produce significant thermonuclear burn from a target driven with a laser or ion beam. To achieve that goal, the national ICF Program has proposed a laser capable of producing ignition and intermediate gain. The facility is called the National Ignition Facility (NIF). This article describes ignition targets designed for the NIF and their modeling. Although the baseline NIF target design, described herein, is indirect drive, the facility will also be capable of doing direct-drive ignition targets - currently being developed at the University of Rochester.

  11. Volume Ignition via Time-like Detonation in Pellet Fusion

    CERN Document Server

    Csernai, L P

    2015-01-01

    Relativistic fluid dynamics and the theory of relativistic detonation fronts are used to estimate the space-time dynamics of the burning of the D-T fuel in Laser driven pellet fusion experiments. The initial "High foot" heating of the fuel makes the compressed target transparent to radiation, and then a rapid ignition pulse can penetrate and heat up the whole target to supercritical temperatures in a short time, so that most of the interior of the target ignites almost simultaneously and instabilities will have no time to develop. In these relativistic, radiation dominated processes both the interior, time-like burning front and the surrounding space-like part of the front will be stable against Rayleigh-Taylor instabilities. To achieve this rapid, volume ignition the pulse heating up the target to supercritical temperature should provide the required energy in less than ~ 10 ps.

  12. Shock timing on the national ignition facility: First experiments

    International Nuclear Information System (INIS)

    An experimental campaign to tune the initial shock compression sequence of capsule implosions on the National Ignition Facility (NIF) was initiated in late 2010. The experiments use a NIF ignition-scale hohlraum and capsule that employs a re-entrant cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shock sequence is diagnosed with velocity interferometry that provides target performance data used to set the pulse shape for ignition capsule implosions that follow. From the start, these measurements yielded significant new information on target performance, leading to improvements in the target design. We describe the results and interpretation of the initial tuning experiments. (authors)

  13. Shock timing on the National Ignition Facility: First Experiments

    International Nuclear Information System (INIS)

    An experimental campaign to tune the initial shock compression sequence of capsule implosions on the National Ignition Facility (NIF) was initiated in late 2010. The experiments use a NIF ignition-scale hohlraum and capsule that employs a reentrant cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shock sequence is diagnosed with velocity interferometry that provides target performance data used to set the pulse shape for ignition capsule implosions that follow. From the start, these measurements yielded significant new information on target performance, leading to improvements in the target design. We describe the results and interpretation of the initial tuning experiments.

  14. Shock timing on the National Ignition Facility: First Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Celliers, P M; Robey, H F; Boehly, T R; Alger, E; Azevedo, S; Berzins, L V; Bhandarkar, S D; Bowers, M W; Brereton, S J; Callahan, D; Castro, C; Chandrasekaran, H; Choate, C; Clark, D; Coffee, K R; Datte, P S; Dewald, E L; DiNicola, P; Dixit, S; Doeppner, T; Dzenitis, E; Edwards, M J; Eggert, J H; Fair, J; Farley, D R; Frieders, G; Gibson, C R; Giraldez, E; Haan, S; Haid, B; Hamza, A V; Haynam, C; Hicks, D G; Holunga, D M; Horner, J B; Jancaitis, K; Jones, O S; Kalantar, D; Kline, J L; Krauter, K G; Kroll, J J; LaFortune, K N; Pape, S L; Malsbury, T; Maypoles, E R; Milovich, J L; Moody, J D; Moreno, K; Munro, D H; Nikroo, A; Olson, R E; Parham, T; Pollaine, S; Radousky, H B; Ross, G F; Sater, J; Schneider, M B; Shaw, M; Smith, R F; Thomas, C A; Throop, A; Town, R J; Trummer, D; Van Wonterghem, B M; Walters, C F; Widmann, K; Widmayer, C; Young, B K; Atherton, L J; Collins, G W; Landen, O L; Lindl, J D; MacGowan, B J; Meyerhofer, D D; Moses, E I

    2011-10-24

    An experimental campaign to tune the initial shock compression sequence of capsule implosions on the National Ignition Facility (NIF) was initiated in late 2010. The experiments use a NIF ignition-scale hohlraum and capsule that employs a reentrant cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shock sequence is diagnosed with velocity interferometry that provides target performance data used to set the pulse shape for ignition capsule implosions that follow. From the start, these measurements yielded significant new information on target performance, leading to improvements in the target design. We describe the results and interpretation of the initial tuning experiments.

  15. Concept of laser fusion power plant based on fast ignition

    International Nuclear Information System (INIS)

    Recent progress on fast ignition (FI) and cooled Yb:YAG ceramic laser enable us to design an IFE power plant with a 1MJ-class, compact laser whose output energy is 1/4 of previous central ignition scheme. Basing on the FI scheme, we conceptually designed a laser fusion power plant driven with cooled-Yb:YAG, ceramic lasers. The cooled Yb-YAG ceramic was newly chosen as the laser material. We found that the heating laser for ignition could be constructed with the cooled Yb:YAG ceramics as well as the compression laser with acceptable electricity-laser conversion efficiencies including the electric power for the cooling system. A new reactor scheme for a liquid wall reactor that has no stagnation point of ablated gas was proposed. (author)

  16. Central ignition scenarios for TFTR

    International Nuclear Information System (INIS)

    The possibility of obtaining ignition in TFTR by means of very centrally peaked density profiles is examined. It is shown that local central alpha heating can be made to exceed local central energy losses (''central ignition'') under global conditions for which Q greater than or equal to 1. Time dependent 1-D transport simulations show that the normal global ignition requirements are substantially relaxed for plasmas with peaked density profiles. 18 refs., 18 figs

  17. A prediction study of a spark ignition supercharged hydrogen engine

    International Nuclear Information System (INIS)

    Hydrogen is found to be a suitable alternative fuel for spark ignition engines with certain drawbacks, such as high NOx emission and small power output. However, supercharging may solve such problems. In this study, the effects of equivalence ratio, compression ratio and inlet pressure on the performance and NOx emission of a four stroke supercharged hydrogen engine have been analyzed using a specially developed computer program. The results are verified and compared with experimental data obtained from tests on a Ricardo E6/US engine. A chart specifying the safe operation zone of the hydrogen engine has been produced. The safe operation zone means no pre-ignition, acceptable NOx emission, high engine efficiency and lower specific fuel consumption in comparison with the gasoline engine. The study also shows that supercharging is a more effective method to increase the output of a hydrogen engine rather than increasing the compression ratio of the engine at the knock limited equivalence ratio

  18. Investigation of fusion gain in fast ignition with conical targets

    Directory of Open Access Journals (Sweden)

    MJ Tabatabaei

    2011-03-01

    Full Text Available Fast ignition is a new scheme for inertial confinement fusion (ICF. In this scheme, at first the interaction of ultraintense laser beam with the hohlraum wall surrounding a capsule containing deuterium-tritium (D-T fuel causes implosion and compression of fuel to high density and then laser produced protons penetrate in the compressed fuel and deposit their energy in it as the ignition hot spot is created. In this paper, following the energy gain of spherical target and considering relationship of the burn fraction to burn duration, we have obtained the energy gain of conical targets characterized by the angle β, and found a hemispherical capsule (β=π/2 has a gain as high as 96% of that of the whole spherical capsule. The results obtained in this study are qualitatively consistent with Atzeni et al.'s studies of simulations.

  19. A new ignition scheme using hybrid indirect-direct drive for inertial confinement fusion

    OpenAIRE

    Fan, Zhengfeng; Chen, Mo; DAI, ZHENSHENG; Cai, Hong-Bo; Zhu, Shao-ping; Zhang, W. Y.; He, X. T.

    2013-01-01

    A new hybrid indirect-direct-drive ignition scheme is proposed for inertial confinement fusion: a cryogenic capsule encased in a hohlraum is first compressed symmetrically by indirect-drive x-rays, and then accelerated and ignited by both direct-drive lasers and x-rays. A steady high-density plateau newly formed between the radiation and electron ablation fronts suppresses the rarefaction at the radiation ablation front and greatly enhances the drive pressure. Meanwhile, multiple shock reflec...

  20. Propellant-Flow-Actuated Rocket Engine Igniter

    Science.gov (United States)

    Wollen, Mark

    2013-01-01

    A rocket engine igniter has been created that uses a pneumatically driven hammer that, by specialized geometry, is induced into an oscillatory state that can be used to either repeatedly impact a piezoelectric crystal with sufficient force to generate a spark capable of initiating combustion, or can be used with any other system capable of generating a spark from direct oscillatory motion. This innovation uses the energy of flowing gaseous propellant, which by means of pressure differentials and kinetic motion, causes a hammer object to oscillate. The concept works by mass flows being induced through orifices on both sides of a cylindrical tube with one or more vent paths. As the mass flow enters the chamber, the pressure differential is caused because the hammer object is supplied with flow on one side and the other side is opened with access to the vent path. The object then crosses the vent opening and begins to slow because the pressure differential across the ball reverses due to the geometry in the tube. Eventually, the object stops because of the increasing pressure differential on the object until all of the kinetic energy has been transferred to the gas via compression. This is the point where the object reverses direction because of the pressure differential. This behavior excites a piezoelectric crystal via direct impact from the hammer object. The hammer strikes a piezoelectric crystal, then reverses direction, and the resultant high voltage created from the crystal is transferred via an electrode to a spark gap in the ignition zone, thereby providing a spark to ignite the engine. Magnets, or other retention methods, might be employed to favorably position the hammer object prior to start, but are not necessary to maintain the oscillatory behavior. Various manifestations of the igniter have been developed and tested to improve device efficiency, and some improved designs are capable of operation at gas flow rates of a fraction of a gram per second (0

  1. Fast ignition studies at Osaka University

    International Nuclear Information System (INIS)

    After the invention of the chirped pulse amplification technique [1], the extreme conditions of matters have become available in laboratory spaces and can be studied with the use of ultra intense laser pulse (UILP) with a high energy. One such example is the fast ignition [2] where UILP is used to heat a highly compressed fusion fuel core within 1-10 pico-seconds before the core disassembles. It is predicted possible with use of 50-100 kJ lasers for both imploding the fuel and heating [2] to attain a large fusion gain. Fast ignition was shown to be a promising new scheme for laser fusion [3] with a PW (= 1015 W) UILP and GEKKO XII laser systems at Osaka. Many new physics have been found with use of UILP in a relativistic parameter regime during the process of the fast ignition studies. UILP can penetrate into over-dense plasma for a couple hundred microns distance with a self-focusing and relativistic transparency effects. Hot electrons of 1-100 MeV can be easily created and are under studies for its spectral and emission angle controls. Strong magnetic fields of 10's of MGauss are created to guide these hot electrons along the target surface [4]. Based on these results, a new and largest UILP laser machine of 10 kJ energy at PW UILP peak power is under construction to test if we can achieve the sub-ignition fusion condition at Osaka University. The machine requires challenging optical technologies such as large size (0.9 m) gratings, tiling these gratings for UILP compression; segmenting four large UILP beams to obtain diffraction limited focal spot. We would like to over-view all of these activities. References [1]D. STRICKLAND and G. MOUROU, Opt. Commun., 56, 219 (1985) [2] S. ATZENI et al., Phys Plasmas, 6, 3316 (1999) [3] R. KODAMA, K.A. TANAKA et al., Nature, 418, 933 (2002) [4] A.L. LEI, K.A. TANAKA et al., Phys. Rev. Lett., 96, 255006(2006) ; H. HABARA, K.A. TANAKA et al., Phys. Rev. Lett., 97, 095004 (2006)

  2. The National Ignition Facility and the Path to Fusion Energy

    Energy Technology Data Exchange (ETDEWEB)

    Moses, E

    2011-07-26

    The National Ignition Facility (NIF) is operational and conducting experiments at the Lawrence Livermore National Laboratory (LLNL). The NIF is the world's largest and most energetic laser experimental facility with 192 beams capable of delivering 1.8 megajoules of 500-terawatt ultraviolet laser energy, over 60 times more energy than any previous laser system. The NIF can create temperatures of more than 100 million degrees and pressures more than 100 billion times Earth's atmospheric pressure. These conditions, similar to those at the center of the sun, have never been created in the laboratory and will allow scientists to probe the physics of planetary interiors, supernovae, black holes, and other phenomena. The NIF's laser beams are designed to compress fusion targets to the conditions required for thermonuclear burn, liberating more energy than is required to initiate the fusion reactions. Experiments on the NIF are focusing on demonstrating fusion ignition and burn via inertial confinement fusion (ICF). The ignition program is conducted via the National Ignition Campaign (NIC) - a partnership among LLNL, Los Alamos National Laboratory, Sandia National Laboratories, University of Rochester Laboratory for Laser Energetics, and General Atomics. The NIC program has also established collaborations with the Atomic Weapons Establishment in the United Kingdom, Commissariat a Energie Atomique in France, Massachusetts Institute of Technology, Lawrence Berkeley National Laboratory, and many others. Ignition experiments have begun that form the basis of the overall NIF strategy for achieving ignition. Accomplishing this goal will demonstrate the feasibility of fusion as a source of limitless, clean energy for the future. This paper discusses the current status of the NIC, the experimental steps needed toward achieving ignition and the steps required to demonstrate and enable the delivery of fusion energy as a viable carbon-free energy source.

  3. The National Ignition Facility and the Path to Fusion Energy

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF) is operational and conducting experiments at the Lawrence Livermore National Laboratory (LLNL). The NIF is the world's largest and most energetic laser experimental facility with 192 beams capable of delivering 1.8 megajoules of 500-terawatt ultraviolet laser energy, over 60 times more energy than any previous laser system. The NIF can create temperatures of more than 100 million degrees and pressures more than 100 billion times Earth's atmospheric pressure. These conditions, similar to those at the center of the sun, have never been created in the laboratory and will allow scientists to probe the physics of planetary interiors, supernovae, black holes, and other phenomena. The NIF's laser beams are designed to compress fusion targets to the conditions required for thermonuclear burn, liberating more energy than is required to initiate the fusion reactions. Experiments on the NIF are focusing on demonstrating fusion ignition and burn via inertial confinement fusion (ICF). The ignition program is conducted via the National Ignition Campaign (NIC) - a partnership among LLNL, Los Alamos National Laboratory, Sandia National Laboratories, University of Rochester Laboratory for Laser Energetics, and General Atomics. The NIC program has also established collaborations with the Atomic Weapons Establishment in the United Kingdom, Commissariat a Energie Atomique in France, Massachusetts Institute of Technology, Lawrence Berkeley National Laboratory, and many others. Ignition experiments have begun that form the basis of the overall NIF strategy for achieving ignition. Accomplishing this goal will demonstrate the feasibility of fusion as a source of limitless, clean energy for the future. This paper discusses the current status of the NIC, the experimental steps needed toward achieving ignition and the steps required to demonstrate and enable the delivery of fusion energy as a viable carbon-free energy source.

  4. Intermediate species measurement during iso-butanol auto-ignition

    KAUST Repository

    Ji, Weiqi

    2015-10-01

    © 2015 The Combustion Institute.Published by Elsevier Inc. All rights reserved. This work presents the time histories of intermediate species during the auto-ignition of iso-butanol at high pressure and intermediate temperature conditions obtained using a rapid compression machine and recently developed fast sampling system. Iso-butanol ignition delays were acquired for iso-butanol/O2 mixture with an inert/O2 ratio of 7.26, equivalence ratio of 0.4, in the temperature range of 840-950 K and at pressure of 25 bar. Fast sampling and gas chromatography were used to acquire and quantify the intermediate species during the ignition delay of the same mixture at P = 25.3 bar and T = 905 K. The ignition delay times and quantitative measurements of the mole fraction time histories of methane, ethene, propene, iso-butene, iso-butyraldehyde, iso-butanol, and carbon monoxide were compared with predictions from the detailed mechanisms developed by Sarathy et al., Merchant et al., and Cai et al. It is shown that while the Sarathy mechanism well predicts the overall ignition delay time, it overpredicts ethene by a factor of 6-10, underpredicts iso-butene by a factor of 2, and overpredicts iso-butyraldehyde by a factor of 2. Reaction path and sensitivity analyses were carried out to identify the reactions responsible for the observed inadequacy. The rates of iso-butanol hydrogen atom abstraction by OH radical and the beta-scission reactions of hydroxybutyl radicals were updated based on recently published quantum calculation results. Significant improvements were achieved in predicting ignition delay at high pressures (25 and 30 bar) and the species concentrations of ethene and iso-butene. However, the updated mechanism still overpredicts iso-butyraldehyde concentrations. Also, the updated mechanism degrades the prediction in ignition delay at lower pressure (15 bar) compared to the original mechanism developed by Sarathy et al.

  5. Experimental validation of concentration profiles in an HCCI engine, modelled by a multi-component kinetic mechanism: Outline for auto-ignition and emission control

    Energy Technology Data Exchange (ETDEWEB)

    Machrafi, Hatim, E-mail: hatim-machrafi@enscp.f [UPMC Universite Paris 06, Ecole Nationale Superieure de Chimie de Paris, 11, rue de Pierre et Marie Curie, 75005 Paris (France); Universite de Liege, Thermodynamique des Phenomenes Irreversibles, 17, Allee du Six-Aout, 4000 Liege (Belgium)

    2010-10-15

    In order to contribute to the auto-ignition and emission control for Homogeneous Charge Compression Ignition (HCCI), a kinetic multi-component mechanism, containing 62 reactions and 49 species for mixtures of n-heptane, iso-octane and toluene is validated in this work, comparing for the concentration profiles of the fuel, the total hydrocarbons, O{sub 2}, CO{sub 2}, CO, acetaldehyde and iso-butene. These species are sampled during the combustion and quantified. For these measurements an automotive exhaust analyser, a gas chromatograph, coupled to a mass spectrometer and a flame ionisation detector are used, depending on the species to be measured. The fuel, total hydrocarbons, O{sub 2}, CO{sub 2}, iso-butene and acetaldehyde showed a satisfactory quantitative agreement between the mechanism and the experiments. Both the experiments and the modelling results showed the same formation behaviour of the different species. An example is shown of how such a validated mechanism can provide for a set of information of the behaviour of the auto-ignition process and the emission control as a function of engine parameters.

  6. Analysis of Ignition and Combustion in Otto Lean-Burn Engines with Prechambers

    OpenAIRE

    Norum, Viggo Lauritz

    2008-01-01

    Otto-engines in which the combustion chamber has richer fuel/air mix close to the ignition source and leaner charge further away from the ignition source are often called "stratified charge engines". Stratified charge can be used to increase the combustion speed in an internal combustion engine and thereby enable the engine to run on a fuel/air mix that would normally burn too slowly or not burn at all. The use of prechambers is one way to obtain stratified charge.This thesis presents and use...

  7. Fuel Effects on Ignition and Their Impact on Advanced Combustion Engines (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, J.; Li, H.; Neill, S.

    2006-08-01

    The objective of this report is to develop a pathway to use easily measured ignition properties as metrics for characterizing fuels in advanced combustion engine research--correlate IQT{trademark} measured parameters with engine data. In HCCL engines, ignition timing depends on the reaction rates throughout compression stroke: need to understand sensitivity to T, P, and [O{sub 2}]; need to rank fuels based on more than one set of conditions; and need to understand how fuel composition (molecular species) affect ignition properties.

  8. Fast-ignition heavy-ion fusion target by jet impact

    Energy Technology Data Exchange (ETDEWEB)

    Velarde, P. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/ Jose Gutierrez Abascal, 2. 28006 Madrid (Spain)]. E-mail: pedro@din.upm.es; Ogando, F. [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, C/ Jose Gutierrez Abascal, 2. 28006 Madrid (Spain); Universidad Nacional de Educacion a Distancia (Spain); Eliezer, S. [Soreq Nuclear Research Center (Israel); Martinez-Val, J.M. [Soreq Nuclear Research Center (Israel)

    2005-05-21

    A new target design for HIF, based on the fast-ignition principles, is proposed. Unlike the previous designs proposed so far, in this case just one energy source is needed to drive the whole process to ignition. The ultra-fast deposition of energy onto the compressed core is produced in this case by hypervelocity jets generated during the process. The collision of jets converts their kinetic energy into thermal energy of the nuclear fuel, which is expected to produce ignition under proper design. The process is studied in this paper, describing its most relevant features like jet production and later collision.

  9. Ignition and Inertial Confinement Fusion at The National Ignition Facility

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and for studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). The NIF is now conducting experiments to commission the laser drive, the hohlraum and the capsule and to develop the infrastructure needed to begin the first ignition experiments in FY 2010. Demonstration of ignition and thermonuclear burn in the laboratory is a major NIF goal. NIF will achieve this by concentrating the energy from the 192 beams into a mm3-sized target and igniting a deuterium-tritium mix, liberating more energy than is required to initiate the fusion reaction. NIF's ignition program is a national effort managed via the National Ignition Campaign (NIC). The NIC has two major goals: execution of DT ignition experiments starting in FY2010 with the goal of demonstrating ignition and a reliable, repeatable ignition platform by the conclusion of the NIC at the end of FY2012. The NIC will also develop the infrastructure and the processes required to operate NIF as a national user facility. The achievement of ignition at NIF will demonstrate the scientific feasibility of ICF and focus worldwide attention on laser fusion as a viable energy option. A laser fusion-based energy concept that builds on NIF, known as LIFE (Laser Inertial Fusion Energy), is currently under development. LIFE is inherently safe and can provide a global carbon-free energy generation solution in the 21st century. This paper describes recent progress on NIF, NIC, and the LIFE concept.

  10. Ignition and inertial confinement fusion at the National Ignition Facility

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and for studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). The NIF is now conducting experiments to commission the laser drive, the hohlraum and the capsule and to develop the infrastructure needed to begin the first ignition experiments in FY 2010. Demonstration of ignition and thermonuclear burn in the laboratory is a major NIF goal. NIF will achieve this by concentrating the energy from the 192 beams into a mm3-sized target and igniting a deuterium-tritium mix, liberating more energy than is required to initiate the fusion reaction. NIF's ignition program is a national effort managed via the National Ignition Campaign (NIC). The NIC has two major goals: execution of DT ignition experiments starting in FY2010 with the goal of demonstrating ignition and a reliable, repeatable ignition platform by the conclusion of the NIC at the end of FY2012. The NIC will also develop the infrastructure and the processes required to operate NIF as a national user facility. The achievement of ignition at NIF will demonstrate the scientific feasibility of ICF and focus worldwide attention on laser fusion as a viable energy option. A laser fusion-based energy concept that builds on NIF, known as LIFE (Laser Inertial Fusion Energy), is currently under development. LIFE is inherently safe and can provide a global carbon-free energy generation solution in the 21st century. This paper describes recent progress on NIF, NIC, and the LIFE concept.

  11. Energy gain of ignitable targets in inertial confinement fusion (ICF)

    OpenAIRE

    A. Parvazian,J Jafari

    2002-01-01

      In order to determine the fusion energy gain in a target due to inertial confinement fusion, it is necessary to solve hydrodynamic equations governed on plasma behavior during confinement time. To compress spherical multilayer targets having fuel in the central part, they are irradiated by laser or heavy ion beams. A suitable mass ratio of a pusher is used to ignite the central part of the target. When compression is maximum, fuel density exceeds from 500 to 1000 times of the cold density. ...

  12. Data Analysis, Pre-Ignition Assessment, and Post-Ignition Modeling of the Large-Scale Annular Cookoff Tests

    Energy Technology Data Exchange (ETDEWEB)

    G. Terrones; F.J. Souto; R.F. Shea; M.W.Burkett; E.S. Idar

    2005-09-30

    In order to understand the implications that cookoff of plastic-bonded explosive-9501 could have on safety assessments, we analyzed the available data from the large-scale annular cookoff (LSAC) assembly series of experiments. In addition, we examined recent data regarding hypotheses about pre-ignition that may be relevant to post-ignition behavior. Based on the post-ignition data from Shot 6, which had the most complete set of data, we developed an approximate equation of state (EOS) for the gaseous products of deflagration. Implementation of this EOS into the multimaterial hydrodynamics computer program PAGOSA yielded good agreement with the inner-liner collapse sequence for Shot 6 and with other data, such as velocity interferometer system for any reflector and resistance wires. A metric to establish the degree of symmetry based on the concept of time of arrival to pin locations was used to compare numerical simulations with experimental data. Several simulations were performed to elucidate the mode of ignition in the LSAC and to determine the possible compression levels that the metal assembly could have been subjected to during post-ignition.

  13. Magnetic Flux Compression Concept for Nuclear Pulse Propulsion and Power

    Science.gov (United States)

    Litchford, Ronald J.

    2000-01-01

    The desire for fast, efficient interplanetary transport requires propulsion systems having short acceleration times and very high specific impulse attributes. Unfortunately, most highly efficient propulsion systems which are within the capabilities of present day technologies are either very heavy or yield very low impulse such that the acceleration time to final velocity is too long to be of lasting interest, One exception, the nuclear thermal thruster, could achieve the desired acceleration but it would require inordinately large mass ratios to reach the range of desired final velocities. An alternative approach, among several competing concepts that are beyond our modern technical capabilities, is a pulsed thermonuclear device utilizing microfusion detonations. In this paper, we examine the feasibility of an innovative magnetic flux compression concept for utilizing microfusion detonations, assuming that such low yield nuclear bursts can be realized in practice. In this concept, a magnetic field is compressed between an expanding detonation driven diamagnetic plasma and a stationary structure formed from a high temperature superconductor (HTSC). In general, we are interested in accomplishing two important functions: (1) collimation of a hot diamagnetic plasma for direct thrust production; and (2) pulse power generation for dense plasma ignition. For the purposes of this research, it is assumed that rnicrofusion detonation technology may become available within a few decades, and that this approach could capitalize on recent advances in inertial confinement fusion ICF) technologies including magnetized target concepts and antimatter initiated nuclear detonations. The charged particle expansion velocity in these detonations can be on the order of 10 (exp 6)- 10 (exp 7) meters per second, and, if effectively collimated by a magnetic nozzle, can yield the Isp and the acceleration levels needed for practical interplanetary spaceflight. The ability to ignite pure

  14. Rocket Ignition Demonstrations Using Silane

    Science.gov (United States)

    Pal, Sibtosh; Santoro, Robert; Watkins, William B.; Kincaid, Kevin

    1998-01-01

    Rocket ignition demonstration tests using silane were performed at the Penn State Combustion Research Laboratory. A heat sink combustor with one injection element was used with gaseous propellants. Mixtures of silane and hydrogen were used as fuel, and oxygen was used as oxidizer. Reliable ignition was demonstrated using fuel lead and and a swirl injection element.

  15. Piezoelectrically Initiated Pyrotechnic Igniter

    Science.gov (United States)

    Quince, Asia; Dutton, Maureen; Hicks, Robert; Burnham, Karen

    2013-01-01

    This innovation consists of a pyrotechnic initiator and piezoelectric initiation system. The device will be capable of being initiated mechanically; resisting initiation by EMF, RF, and EMI (electromagnetic field, radio frequency, and electromagnetic interference, respectively); and initiating in water environments and space environments. Current devices of this nature are initiated by the mechanical action of a firing pin against a primer. Primers historically are prone to failure. These failures are commonly known as misfires or hang-fires. In many cases, the primer shows the dent where the firing pin struck the primer, but the primer failed to fire. In devices such as "T" handles, which are commonly used to initiate the blowout of canopies, loss of function of the device may result in loss of crew. In devices such as flares or smoke generators, failure can result in failure to spot a downed pilot. The piezoelectrically initiated ignition system consists of a pyrotechnic device that plugs into a mechanical system (activator), which on activation, generates a high-voltage spark. The activator, when released, will strike a stack of electrically linked piezo crystals, generating a high-voltage, low-amperage current that is then conducted to the pyro-initiator. Within the initiator, an electrode releases a spark that passes through a pyrotechnic first-fire mixture, causing it to combust. The combustion of the first-fire initiates a primary pyrotechnic or explosive powder. If used in a "T" handle, the primary would ramp the speed of burn up to the speed of sound, generating a shock wave that would cause a high explosive to go "high order." In a flare or smoke generator, the secondary would produce the heat necessary to ignite the pyrotechnic mixture. The piezo activator subsystem is redundant in that a second stack of crystals would be struck at the same time with the same activation force, doubling the probability of a first strike spark generation. If the first

  16. Indirect-direct hybrid-drive work-dominated hotspot ignition for inertial confinement fusion

    OpenAIRE

    He, X. T.; Fan, Z. F.; Li, J.W.; Liu, J; Lan, K.; Wu, J F; Wang, L F; Ye, W. H.

    2015-01-01

    An indirect-direct hybrid-drive work-dominated hotspot ignition scheme for inertial confinement fusion is proposed: a layered fuel capsule inside a spherical hohlraum with an octahedral symmetry is compressed first by indirect-drive soft-x rays (radiation) and then by direct-drive lasers in last pulse duration. In this scheme, an enhanced shock and a follow-up compression wave for ignition with pressure far greater than the radiation ablation pressure are driven by the direct-drive lasers, an...

  17. Calculation of fusion gain in fast ignition with magnetic target by relativistic electrons and protons

    OpenAIRE

    A. Parvazian; A Javani

    2010-01-01

    Fast ignition is a new method for inertial confinement fusion (ICF) in which the compression and ignition steps are separated. In the first stage, fuel is compressed by laser or ion beams. In the second phase, relativistic electrons are generated by pettawat laser in the fuel. Also, in the second phase 5-35 MeV protons can be generated in the fuel. Electrons or protons can penetrate in to the ultra-dense fuel and deposit their energy in the fuel . More recently, cylindrical rather than spheri...

  18. The National Ignition Facility

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF) is the largest construction project ever undertaken at Lawrence Livermore National Laboratory (LLNL). NIF consists of 192 forty-centimeter-square laser beams and a 10-m-diameter target chamber. NIF is being designed and built by an LLNL-led team from Los Alamos National Laboratory, Sandia National Laboratories, the University of Rochester, and LLNL. Physical construction began in 1997. The Laser and Target Area Building and the Optics Assembly Building were the first major construction activities, and despite several unforeseen obstacles, the buildings are now 92% complete and have been done on time and within cost. Prototype component development and testing has proceeded in parallel. Optics vendors have installed full-scale production lines and have done prototype production runs. The assembly and integration of the beampath infrastructure has been reconsidered and a new approach has been developed. This paper will discuss the status of the NIF project and the plans for completion. (author)

  19. A rapid-compression-machine study of gaseous fuel injection and combustion

    OpenAIRE

    Klimkiewicz, Dariusz; Leżański, Tomasz; Jarnicki, Rafael; Rychter, Tadeusz J.

    2015-01-01

    Rapid-compression-machine studies of an enginećs combustion system with the direct injection of gaseous fuel were made. The very short time available for the injection, combined with the poor penetration and mixing of the gas jet with the surrounding air, caused the serious problems with combustion initiation. One of the solutions to facilitate the ignition seems to be the use of a small ignition prechamber. The ignition takes place within the prechamber and the hot, chemically active combust...

  20. Time Compression

    OpenAIRE

    Aadland, David; Shaffer, Sherrill

    2012-01-01

    Economists have generally ignored the notion that perceived time may differ from clock time. Borrowing from the behavioral psychology literature, we investigate the case of time compression whereby perceived time passes more quickly than actual time. A framework is presented to embed time compression in economic models. We then apply the principle to a standard lifecycle permanent income model with endogenous labor. Time compression provides an alternative explanation of why older indi...

  1. Semiconductor bridge, SCB, ignition studies of Al/CuO thermite

    Energy Technology Data Exchange (ETDEWEB)

    Bickes, R.W. Jr.; Wackerbarth, D.E. [Sandia National Labs., Albuquerque, NM (United States); Mohler, J.H. [Energetic Materials Associates, Inc., Vero Beach, FL (United States)

    1997-04-01

    The authors briefly summarize semiconductor bridge operation and review their ignition studies of Al/CuO thermite as a function of the capacitor discharge unit (CDU) firing set capacitance, charge holder material and morphology of the CuO. Ignition thresholds were obtained using a brass charge holder and a non-conducting fiber-glass-epoxy composite material, G10. At - 18 C and a charge voltage of 50V, the capacitance thresholds were 30.1 {mu}F and 2.0 {mu}F respectively. They also present new data on electrostatic discharge (ESD) and radio frequency (RF) vulnerability tests.

  2. The National Ignition Facility Project

    International Nuclear Information System (INIS)

    The mission of the National Ignition Facility is to achieve ignition and gain in ICF targets in the laboratory. The facility will be used for defense applications such as weapons physics and weapons effect testing, and for civilian applications such as fusion energy development and fundamental studies of matter at high temperatures and densities. This paper reviews the design, schedule and costs associated with the construction project

  3. Alcohol ignition interlock programs.

    Science.gov (United States)

    Beirness, D J; Marques, P R

    2004-09-01

    The alcohol ignition interlock is an in-vehicle DWI control device that prevents a car from starting until the operator provides a breath alcohol concentration (BAC) test below a set level, usually .02% (20 mg/dl) to .04% (40 mg/dl). The first interlock program was begun as a pilot test in California 18 years ago; today all but a few US states, and Canadian provinces have interlock enabling legislation. Sweden has recently implemented a nationwide interlock program. Other nations of the European Union and as well as several Australian states are testing it on a small scale or through pilot research. This article describes the interlock device and reviews the development and current status of interlock programs including their public safety benefit and the public practice impediments to more widespread adoption of these DWI control devices. Included in this review are (1) a discussion of the technological breakthroughs and certification standards that gave rise to the design features of equipment that is in widespread use today; (2) a commentary on the growing level of adoption of interlocks by governments despite the judicial and legislative practices that prevent more widespread use of them; (3) a brief overview of the extant literature documenting a high degree of interlock efficacy while installed, and the rapid loss of their preventative effect on repeat DWI once they are removed from the vehicles; (4) a discussion of the representativeness of subjects in the current research studies; (5) a discussion of research innovations, including motivational intervention efforts that may extend the controlling effect of the interlock, and data mining research that has uncovered ways to use the stored interlock data record of BAC tests in order to predict high risk drivers; and (6) a discussion of communication barriers and conceptual rigidities that may be preventing the alcohol ignition interlock from taking a more prominent role in the arsenal of tools used to control

  4. Compressed Teleportation

    CERN Document Server

    Jaffe, Arthur; Wozniakowski, Alex

    2016-01-01

    In a previous paper we introduced holographic software for quantum networks, inspired by work on planar para algebras. This software suggests the definition of a compressed transformation. Here we utilize the software to find a CT protocol to teleport compressed transformations. This protocol serves multiple parties with multiple persons.

  5. Theory of Fast Electron Transport for Fast Ignition

    CERN Document Server

    Robinson, A P L; Davies, J R; Gremillet, L; Honrubia, J J; Johzaki, T; Kingham, R J; Sherlock, M; Solodov, A A

    2013-01-01

    Fast Ignition Inertial Confinement Fusion is a variant of inertial fusion in which DT fuel is first compressed to high density and then ignited by a relativistic electron beam generated by a fast (< 20 ps) ultra-intense laser pulse, which is usually brought in to the dense plasma via the inclusion of a re-entrant cone. The transport of this beam from the cone apex into the dense fuel is a critical part of this scheme, as it can strongly influence the overall energetics. Here we review progress in the theory and numerical simulation of fast electron transport in the context of Fast Ignition. Important aspects of the basic plasma physics, descriptions of the numerical methods used, a review of ignition-scale simulations, and a survey of schemes for controlling the propagation of fast electrons are included. Considerable progress has taken place in this area, but the development of a robust, high-gain FI `point design' is still an ongoing challenge.

  6. National Ignition Facility: Experimental plan

    International Nuclear Information System (INIS)

    As part of the Conceptual Design Report (CDR) for the National Ignition Facility (NIF), scientists from Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), the University of Rochester's Laboratory for Laser Energetics (UR/LLE), and EG ampersand G formed an NIF Target Diagnostics Working Group. The purpose of the Target Diagnostics Working Group is to prepare conceptual designs of target diagnostics for inclusion in the facility CDR and to determine how these specifications impact the CDR. To accomplish this, a subgroup has directed its efforts at constructing an approximate experimental plan for the ignition campaign of the NIF CDR. The results of this effort are contained in this document, the Experimental Plan for achieving fusion ignition in the NIF. This group initially concentrated on the flow-down requirements of the experimental campaign leading to ignition, which will dominate the initial efforts of the NIF. It is envisaged, however, that before ignition, there will be parallel campaigns supporting weapons physics, weapons effects, and other research. This plan was developed by analyzing the sequence of activities required to finally fire the laser at the level of power and precision necessary to achieve the conditions of an ignition hohlraum target, and to then use our experience in activating and running Nova experiments to estimate the rate of completing these activities

  7. Performance of compression ignition engine with mahua (Madhuca indica) biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    H. Raheman; S.V. Ghadge [Indian Institute of Technology, Kharagpur (India). Agricultural and Food Engineering Department

    2007-11-15

    The performance of biodiesel obtained from mahua oil and its blend with high speed diesel in a Ricardo E6 engine has been presented in this paper together with some of its fuel properties. These properties were found to be comparable to diesel and confirming to both the American and European standards. Engine performance (brake specific fuel consumption, brake thermal efficiency and exhaust gas temperature) and emissions (CO, smoke density and NOx) were measured to evaluate and compute the behaviour of the diesel engine running on biodiesel. The reductions in exhaust emissions and brake specific fuel consumption together with increase brake power, brake thermal efficiency made the blend of biodiesel (B20) a suitable alternative fuel for diesel and thus could help in controlling air pollution. 21 refs., 6 figs., 3 tabs.

  8. NOx reduction from compression ignition engines with pulsed corona discharge

    International Nuclear Information System (INIS)

    A study of pulsed corona discharge technology for NOx reduction from diesel engine exhaust is presented. The pulsed corona reactor consists of two coaxial cylinders used as electrodes of opposite polarities. The results are presented in terms of the cleanness (mass of NOx removed relative to its initial mass), and the efficiency (the energy required to theoretically dissociate 1 g of NOx, relative to the energy actually needed). Experimental results show that for a pulsed corona, the polarity of the electrodes has no significant effect on the reactor performance. Cleanness was found to be independent of the engine load. The pulsed corona reactor design considers the most efficient means of energy transfer from pulse-forming capacitor to the discharge zone. It is shown experimentally that an external electrode of smaller diameter provides better NOx reduction. For a pulsed corona reactor, the residence time that provides the best performance must be sufficient to allow all the pollutant molecules to interact with the radicals produced by the corona discharge. The residence time is calculated for the pulsed corona reactor and experimentally confirmed to be the one that results in the best cleanness and efficiency of NOx removal. The empirical relations, based on working conditions, are obtained and provide a route for reactor design

  9. Design Considerations for a Cone in a Fast Ignition Capsule

    International Nuclear Information System (INIS)

    An alternative to inertial fusion with central ignition is 'fast ignition', in which one laser compresses the DT fuel adiabatically and a second laser with a short, very intense pulse heats the compressed core with super-thermal electrons. One approach to fast ignition entails the introduction of the second laser beam via a hollow cone that pierces the side of the capsule. Critical considerations for the design of the cone in such an experiment include: (1) perturbation of the implosion by the cone; (2) minimization of the column density of material between the critical density surface for the ignitor beam and the converged high density region; (3) positioning, alignment, and shape of the cone to minimize deleterious hydrodynamic effects; and (4) effect of radiation gradients around the cone on the symmetry of the implosion. This study entails the 2D and 3D simulations of a fast-ignitor experiment having a cryogenic deuterium-tritium capsule imploded within a high-Z hohlraum heated by about 650 kJ of 3ω laser beams on the NIF.

  10. A low cost igniter utilizing an SCB and titanium sub-hydride potassium perchlorate pyrotechnic

    Science.gov (United States)

    Bickes, R. W., Jr.; Grubelich, M. C.; Hartman, J. K.; McCampbell, C. B.; Churchill, J. K.

    1994-01-01

    A conventional NSI (NASA Standard Initiator) normally employs a hot-wire ignition element to ignite ZPP (zirconium potassium perchlorate). With minor modifications to the interior of a header similar to an NSI device to accommodate an SCB (semiconductor bridge), a low cost initiator was obtained. In addition, the ZPP was replaced with THKP (titanium sub-hydride potassium perchlorate) to obtain increased overall gas production and reduced static-charge sensitivity. This paper reports on the all-fire and no-fire levels obtained and on a dual mix device that uses THKP as the igniter mix and a thermite as the output mix.

  11. Direct numerical simulations of the ignition of a lean biodiesel/air mixture with temperature and composition inhomogeneities at high pressure and intermediate temperature

    KAUST Repository

    Luong, Minhbau

    2014-11-01

    on the HCCI combustion is made to clarify each effect. These results suggest that temperature and composition stratifications together with a well-designed T s(-) φ{symbol} correlation can alleviate an excessive rate of pressure rise and control the ignition-timing in homogeneous charge compression-ignition (HCCI) combustion. © 2014 The Combustion Institute.

  12. Aspects of the bioethanol use at the turbocharged spark ignition engine

    Directory of Open Access Journals (Sweden)

    Obeid Zuhair

    2015-01-01

    Full Text Available In the actual content of pollution regulations for the automotives, the use of alternative fuels becomes a priority of the thermal engine scientific research domain. From this point of view bioethanol can represents a viable alternative fuel for spark ignition engines offering the perspective of pollutant emissions reduction and combustion improvement. The paper presents results of the experimental investigations of a turbo-supercharged spark ignition engine (developed from a natural admission spark ignition engine fuelled with gasoline fuelled with bioethanol-gasoline blends. The engine is equipped with a turbocharger for low pressure supercharging, up till 1.4 bar. An correlation between air supercharging pressure-compression ratio-dosage-spark ignition timing-brake power is establish to avoid knocking phenomena at the engine operate regime of full load and 3000 min-1. The influences of the bioethanol on pollutant emissions level are presented.

  13. Numerical and Experimental Study on the Combustion and Emission Characteristics of a Dimethyl Ether (DME Fueled Compression Ignition Engine Études numériques et expérimentales sur les caractéristiques de combustion et d’émissions d’un éther diméthylique (EDM- moteur à auto-allumage rempli de combustible

    Directory of Open Access Journals (Sweden)

    Kim Hyung Jun

    2012-05-01

    Full Text Available A numerical investigation was carried out to study on the combustion and emission characteristics of dimethyl ether (DME with wide ranges of injection timings in compression ignition engines. In order to simulate DME combustion processes, a KIVA-3V code coupled with a chemistry solver was used to solve the detailed chemical kinetics model of DME oxidation. In addition, the Kelvin-Helmholtz-Rayleigh-Taylor (KH-RT hybrid breakup model and Renormalization Group (RNG k-ε  models were applied to analyze the spray characteristics and turbulent flow, respectively. To predict the NOx formation during DME combustion, a reduced Gas Research Institute (GRI NO mechanism was used. From these results on the combustion and emission, the calculated results were compared with experimental ones for the same operating conditions. In the combustion characteristics, the calculated combustion pressure and heat release rates agreed well with experimental results. The levels of experimental NOx emissions was reduced as the start of the injection timing retarded, and also these trends appeared in calculated emission characteristics. Additionally, the calculated CO and HC emissions show an increasing trend as the start of the injection is retarded. Dans cette étude, nous considérons la simulation de la combustion du dimethyl ether (DME dans un moteur à allumage par compression. Les caractéristiques de la combustion ainsi que les émissions polluantes sont analysées sur une large gamme d’avance à l’injection. Afin de simuler le processus de combustion du EDM, le code KIVA-3V couplé à un solveur chimique a été utilisé pour résoudre la cinétique détaillée de l’oxydation du EDM. Le modèle de rupture de Kelvin-Helmholtz-Rayleigh- Taylor (KH-RT ainsi que le modèle de turbulence k-ε  RNG ont été appliqués pour analyser respectivement les caractéristiques du jet et l’écoulement turbulent. Pour prévoir la formation de NOx pendant la combustion

  14. Experimental and Kinetic Modeling Study of Methanol Ignition and Oxidation at High Pressure

    DEFF Research Database (Denmark)

    Aranda, V.; Christensen, J. M.; Alzueta, Maria;

    2013-01-01

    conditions studied, the onset temperature for methanol oxidation was not dependent on the stoichiometry, whereas increasing pressure shifted the ignition temperature toward lower values. Model predictions of the present experimental results, as well as rapid compression machine data from the literature, were...

  15. Indirect-direct hybrid-drive work-dominated hotspot ignition for inertial confinement fusion

    CERN Document Server

    He, X T; Li, J W; Liu, J; Lan, K; Wu, J F; Wang, L F; Ye, W H

    2015-01-01

    An indirect-direct hybrid-drive work-dominated hotspot ignition scheme for inertial confinement fusion is proposed: a layered fuel capsule inside a spherical hohlraum with an octahedral symmetry is compressed first by indirect-drive soft-x rays (radiation) and then by direct-drive lasers in last pulse duration. In this scheme, an enhanced shock and a follow-up compression wave for ignition with pressure far greater than the radiation ablation pressure are driven by the direct-drive lasers, and provide large pdV work to the hotspot to perform the work-dominated ignition. The numerical simulations show that the enhanced shock stops the reflections of indirect-drive shock at the main fuel-hotspot interface, and therefore significantly suppresses the hydrodynamic instabilities and asymmetry. Based on the indirect-drive implosion dynamics the hotspot is further compressed and heated by the enhanced shock and follow-up compression wave, resulting in the work-dominated hotspot ignition and burn with a maximal implos...

  16. Inertial Confinement Fusion and the National Ignition Facility (NIF)

    Energy Technology Data Exchange (ETDEWEB)

    Ross, P.

    2012-08-29

    Inertial confinement fusion (ICF) seeks to provide sustainable fusion energy by compressing frozen deuterium and tritium fuel to extremely high densities. The advantages of fusion vs. fission are discussed, including total energy per reaction and energy per nucleon. The Lawson Criterion, defining the requirements for ignition, is derived and explained. Different confinement methods and their implications are discussed. The feasibility of creating a power plant using ICF is analyzed using realistic and feasible numbers. The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is shown as a significant step forward toward making a fusion power plant based on ICF. NIF is the world’s largest laser, delivering 1.8 MJ of energy, with a peak power greater than 500 TW. NIF is actively striving toward the goal of fusion energy. Other uses for NIF are discussed.

  17. Multimodal Friction Ignition Tester

    Science.gov (United States)

    Davis, Eddie; Howard, Bill; Herald, Stephen

    2009-01-01

    The multimodal friction ignition tester (MFIT) is a testbed for experiments on the thermal and mechanical effects of friction on material specimens in pressurized, oxygen-rich atmospheres. In simplest terms, a test involves recording sensory data while rubbing two specimens against each other at a controlled normal force, with either a random stroke or a sinusoidal stroke having controlled amplitude and frequency. The term multimodal in the full name of the apparatus refers to a capability for imposing any combination of widely ranging values of the atmospheric pressure, atmospheric oxygen content, stroke length, stroke frequency, and normal force. The MFIT was designed especially for studying the tendency toward heating and combustion of nonmetallic composite materials and the fretting of metals subjected to dynamic (vibrational) friction forces in the presence of liquid oxygen or pressurized gaseous oxygen test conditions approximating conditions expected to be encountered in proposed composite material oxygen tanks aboard aircraft and spacecraft in flight. The MFIT includes a stainless-steel pressure vessel capable of retaining the required test atmosphere. Mounted atop the vessel is a pneumatic cylinder containing a piston for exerting the specified normal force between the two specimens. Through a shaft seal, the piston shaft extends downward into the vessel. One of the specimens is mounted on a block, denoted the pressure block, at the lower end of the piston shaft. This specimen is pressed down against the other specimen, which is mounted in a recess in another block, denoted the slip block, that can be moved horizontally but not vertically. The slip block is driven in reciprocating horizontal motion by an electrodynamic vibration exciter outside the pressure vessel. The armature of the electrodynamic exciter is connected to the slip block via a horizontal shaft that extends into the pressure vessel via a second shaft seal. The reciprocating horizontal

  18. Fast Camera Imaging of Hall Thruster Ignition

    International Nuclear Information System (INIS)

    Hall thrusters provide efficient space propulsion by electrostatic acceleration of ions. Rotating electron clouds in the thruster overcome the space charge limitations of other methods. Images of the thruster startup, taken with a fast camera, reveal a bright ionization period which settles into steady state operation over 50 (micro)s. The cathode introduces azimuthal asymmetry, which persists for about 30 (micro)s into the ignition. Plasma thrusters are used on satellites for repositioning, orbit correction and drag compensation. The advantage of plasma thrusters over conventional chemical thrusters is that the exhaust energies are not limited by chemical energy to about an electron volt. For xenon Hall thrusters, the ion exhaust velocity can be 15-20 km/s, compared to 5 km/s for a typical chemical thruster.

  19. Calculation of energy deposited and stopping range through deuterium ignition beam and dynamical studies on the energy gain in D-3He mixtures

    OpenAIRE

    Hosseinimotlagh, S. N.; Jahedi, M.; Kianafraz, S.; Ghaderi, Sakineh

    2015-01-01

    The fast ignition approach to ICF consists in first compressing the fuel to high density by a suitable driver and then creating the hot spot required for ignition by means of a second external pulse. If the ignition beam is composed of deuterons, an additional energy is delivered to the target with increased energy gain. Therefore ,in this innovative suggestion ,we consider deuterium  beams for fast ignition in D+3He mixture and solve the dynamical  balance equations under the available  physi...

  20. SCB thermite igniter studies

    Energy Technology Data Exchange (ETDEWEB)

    Bickes, R.W. Jr.; Wackerbarth, D.E. [Sandia National Labs., Albuquerque, NM (United States); Mohler, J.H. [Energetic Materials Associates, Inc., Vero Beach, FL (United States)

    1996-12-31

    The authors report on recent studies comparing the ignition threshold of temperature cycled, SCB thermite devices with units that were not submitted to temperature cycling. Aluminum/copper-oxide thermite was pressed into units at two densities, 45% of theoretical maximum density (TMD) or 47% of TMD. Half of each of the density sets underwent three thermal cycles; each cycle consisted of 2 hours at 74 C and 2 hours at {minus}54 C, with a 5 minute maximum transfer time between temperatures. The temperature cycled units were brought to ambient temperature before the threshold testing. Both the density and the thermal cycling affected the all-fire voltage. Using a 5.34 {micro}F CDU (capacitor discharge unit) firing set, the all-fire voltage for the units that were not temperature cycled increased with density from 32.99 V (45% TMD) to 39.32 V (47% TMD). The all-fire voltages for the thermally cycled units were 34.42 V (45% TMD) and 58.1 V (47% TMD). They also report on no-fire levels at ambient temperature for two component designs; the 5 minute no-fire levels were greater than 1.2 A. Units were also subjected to tests in which 1 W of RF power was injected into the bridges at 10 MHz for 5 minutes. The units survived and fired normally afterwards. Finally, units were subjected to pin-to-pin electrostatic discharge (ESD) tests. None of the units fired upon application of the ESD pulse, and all of the tested units fired normally afterwards.

  1. Characterization of a two-dimensional temperature field within a rapid compression machine using a toluene planar laser-induced fluorescence imaging technique

    International Nuclear Information System (INIS)

    The homogeneous charge compression ignition (HCCI) combustion process is an advanced operating mode for automotive engines. The self-ignition mechanisms that occur within the combustion chamber exhibit extreme temperature dependence. Therefore, the thorough understanding of corresponding phenomena requires the use of diagnostic methods featuring a sufficient thermal sensitivity, applicable in severe conditions similar to those encountered within engines. In this respect, toluene planar laser-induced fluorescence (PLIF) is applied to the inert compression flow generated within an optical rapid compression machine (RCM). A relatively simple diagnostic system is retained: a single wavelength excitation device (266 nm) and a single (filtered) collection system. This diagnostic system is associated with an image processing strategy specifically adapted to RCM devices. Despite the severe conditions under consideration (40 bar, 700–950 K), the method allows us to obtain relatively large two-dimensional temperature fields that display a level of description seldom achieved in such devices. In particular the temperature gradients, which play a crucial role in HCCI combustion processes, can be estimated. The present experimental results confirm the good reliability and accuracy of the method. The information gathered with this toluene PLIF method puts in evidence its high potentialities for the study of aero-thermal-reactive processes as they take place in real engine conditions. The retained strategy also brings new possibilities of non-intrusive analysis for flows practically encountered within industrial devices

  2. Main conditions and effectiveness of gas fuel use for powering of dual fuel IC self-ignition engine

    OpenAIRE

    Stefan POSTRZEDNIK; Grzegorz PRZYBYŁA; Zbigniew ŻMUDKA

    2015-01-01

    Internal combustion engines are fuelled mostly with liquid fuels (gasoline, diesel). Nowadays the gaseous fuels are applied as driving fuel of combustion engines. In case of spark ignition engines the liquid fuel (petrol) can be totally replaced by the gas fuels. This possibility in case of compression engines is essentially restricted through the higher self-ignition temperatures of the combustible gases in comparison to classical diesel oil. Solution if this problem can be achieved by using...

  3. Longitudinal compression of ion beams

    International Nuclear Information System (INIS)

    This paper examines the longitudinal compression of ion beams which is necessary in some designs of drivers intended to realize inertial thermonuclear fusion by heavy ions. Taking space-charge forces in the beams into account, two compression schemes are investigated: the first preserves the longitudinal phase-space area of the beams, and the second allows an increase of the phase-space area. The compression-system parameters are optimized for an example of a driver for inertial thermonuclear fusion by heavy ions with an energy of 10 MJ and with a pulse length of 25 ns on the target

  4. Modeling the Shock Ignition of a Copper Oxide Aluminum Thermite

    Science.gov (United States)

    Lee, Kibaek; Stewart, D. Scott; Clemenson, Michael; Glumac, Nick; Murzyn, Christopher

    2015-06-01

    An experimental ``striker confinement'' shock compression test was developed in the Glumac-group at the University of Illinois to study ignition and reaction in composite reactive materials. These include thermitic and intermetallic reactive powders. The test places a sample of materials such as a thermite mixture of copper oxide and aluminum powders that are initially compressed to about 80 percent full density. Two RP-80 detonators simultaneously push steel bars into reactive material and the resulting compression causes shock compaction of the material and rapid heating. At that point one observes significant reaction and propagation of fronts. But the fronts are peculiar in that they are comprised of reactive events that can be traced to the reaction/diffusion of the initially separated reactants of copper oxide and aluminum that react at their mutual interfaces that nominally make copper liquid and aluminum oxide products. We discuss our model of the shock ignition of the copper oxide aluminum thermite in the context of the striker experiment and how a Gibbs formulation model, that includes multi-components for liquid and solid phases of aluminum, copper oxide, copper and aluminum oxide can predict the events observed at the particle scale in the experiments. Supported by HDTRA1-10-1-0020 (DTRA), N000014-12-1-0555 (ONR).

  5. Single and multiple impact ignition of new and aged high explosives in the Steven Impact Test

    Energy Technology Data Exchange (ETDEWEB)

    Chidester, S K; DePiero, A H; Garza, R G; Tarver, C M

    1999-06-01

    Threshold impact velocities for ignition of exothermic reaction were determined for several new and aged HMX-based solid high explosives using three types of projectiles in the Steven Test. Multiple impact threshold velocities were found to be approximately 10% lower in damaged charges that did not react in one or more prior impacts. Projectiles with protrusions that concentrate the friction work in a small volume of explosive reduced the threshold velocities by approximately 30%. Flat projectiles required nearly twice as high velocities for ignition as rounded projectiles. Blast overpressure gauges were used for both pristine and damaged charges to quantitatively measure reaction violence. Reactive flow calculations of single and multiple impacts with various projectiles suggest that the ignition rates double in damaged charges.

  6. Single and multiple impact ignition of new and aged high explosives in the Steven Impact Test

    International Nuclear Information System (INIS)

    Threshold impact velocities for ignition of exothermic reaction were determined for several new and aged HMX-based solid high explosives using three types of projectiles in the Steven Test. Multiple impact threshold velocities were found to be approximately 10% lower in damaged charges that did not react in one or more prior impacts. Projectiles with protrusions that concentrate the friction work in a small volume of explosive reduced the threshold velocities by approximately 30%. Flat projectiles required nearly twice as high velocities for ignition as rounded projectiles. Blast overpressure gauges were used for both pristine and damaged charges to quantitatively measure reaction violence. Reactive flow calculations of single and multiple impacts with various projectiles suggest that the ignition rates double in damaged charges

  7. Thermonuclear Ignition of Dark Galaxies

    CERN Document Server

    Herndon, J M

    2006-01-01

    Dark matter is thought to be at least an order of magnitude more abundant than luminous matter in the Universe, but there has yet to be an unambiguous identification of a wholly dark, galactic-scale structure. There is, however, increasing evidence that VIRGOHI 21 may be a dark galaxy. If VIRGOHI 21 turns out to be composed of dark stars, having approximately the same mass of stars found in luminous galaxies, it will pose an enigma within the framework of current astrophysical models, but will provide strong support for my concept, published in 1994 in the Proceedings of the Royal Society of London, of the thermonuclear ignition of stars by nuclear fission, and the corollary, non-ignition of stars. The possibility of galactic thermonuclear ignition is discussed from that framework and leads to my suggestion that the distribution of luminous stars in a galaxy may simply be a reflection of the galactic distribution of the heavy elements.

  8. Thermal ignition theory applied to diesel engine autoignition

    Energy Technology Data Exchange (ETDEWEB)

    Mellor, A.M.; Russell, S.C. [Vanderbilt Univ., Mechanical Engineering Dept., Nashville, TN (United States); Humer, S.; Seshadri, K. [California Univ., Mechanical and Aerospace Engineering Dept., San Diego, La Jolla, CA (United States)

    2004-06-01

    The diesel community has used one-equation models for ignition delay in engines for decades. The inverse Arrhenius forms characterizing many of these expressions thus lump together liquid fuel evaporation, mixing of the vapour with the charge and the chemical delay. As a result, correlations apply only to the injector, engine and operating conditions tested. Additionally, they typically exhibit energies or temperatures of activation that can be as much as ten times lower than those obtained in well-mixed, controlled systems that isolate and study the chemical delay. Here the latter system is modelled first, using classical analysis techniques. The result is then extended to the relatively straightforward fluid mechanic environment of a laminar counterflow burner to clarify how both chemistry and mixing can be included in a more general one-equation model. This new model is validated with ignition limit data for ethane or ethene with O{sub 2}/N{sub 2} either premixed or unmixed in the counterflow arrangement and liquid diesel fuel in a pool configuration. Since the overall mixing time in this burner is known a priori, the data can be manipulated to yield global chemical ignition delay activation temperatures for these fuels. As expected, the results are equivalent to those measured in shock tubes and combustion tunnels where reactants are premixed before ignition. (Author)

  9. Effects of water chemistry on the destabilization and sedimentation of commercial TiO2 nanoparticles: Role of double-layer compression and charge neutralization.

    Science.gov (United States)

    Hsiung, Chia-En; Lien, Hsing-Lung; Galliano, Alexander Edward; Yeh, Chia-Shen; Shih, Yang-Hsin

    2016-05-01

    Nanomaterials are considered to be emerging contaminants because their release into the environment could cause a threat to our ecosystem and human health. This study aims to evaluate the effects of pH, ions, and humic acid on the destabilization and sedimentation of commercial stabilized TiO2 nanoparticles (NPs) in aquatic environments. The average hydrodynamic size of TiO2 NPs was determined to be 52 ± 19 nm by dynamic light scattering. The zero point charge (ZPC) of the commercial TiO2 NPs was found to occur at pH 6. The stability of commercial TiO2 NPs is independent of its concentration in the range of 50-200 mg/L. In the absence of NaCl, the commercial TiO2 NPs rapidly settled down near pHzpc when the aggregated nanoparticle size surpassed 1 μm. However, when the commercial TiO2 NPs aggregated with the increase of NaCl concentrations, the large aggregates (>1 μm) were found to remain suspended. For example, even at the critical aggregation concentration of NaCl (100 meq/L), TiO2 NP aggregates suspended for 45 min and then slowly deposited. This implies an increase in the exposure risk of NPs. In the presence of Suwannee river humic acid (SRHA), the commercial TiO2 NPs did not settle down until the SRHA concentration increased to 20 mg/L, and were seen to restabilize at SRHA concentrations of 50 mg/L. The uncommon behaviors of the commercial TiO2 NPs we observed may be attributed to the different destabilization mechanisms caused by different species (i.e., NaCl and SRHA) in water. PMID:26938678

  10. Experimental study of columns partially filled with concrete under compressive axial loads Etude expérimentale des colonnes partiellement remplis par le béton sous charge axiale

    Directory of Open Access Journals (Sweden)

    Achoura D.

    2012-09-01

    Full Text Available Dans cette étude, on présente les résultats expérimentaux obtenus sur des poteaux mixtes béton-acier mince réalisés par soudures. Un total de 24 profilés en acier, et en forme de I a été testé sous charge de compression uni-axiale à l’âge de 28 jours. les spécimens ont été réparties comme suit: 4 à vides, 4 partiellement remplies avec un béton ordinaire sans l’addition des connecteurs, 4 renforcés par des connecteurs de cisaillements de type cornière en U, 4 autres l’ont été avec des connecteurs de cisaillements type goujons et 8 restants ont été renforcés avec des liens transversaux d’espacement 100mm, 50mm, soudés aux bouts des ailes opposées. Les principaux paramètres étudiés sont: l’élancement du profilé, le type de connecteur de renforcement. A partir des résultats d’essais obtenus, il est confirmé que les parois minces sont plus sensibles de l’apparition au voilement et la longueur des profilés a un effet considérable sur la capacité portante et le mode de rupture. L’addition des connecteurs de renforcement a confirmé l’augmentation de la charge ultime par rapport aux profilés sans connecteurs. In the present work, results of tests conducted on thin welded steel-concrete stubs are presented. A total of 24 stubs an I steel section were tested under axial compression at 28 days after the date of casting, 4 were empty, 4 filled with normal concrete, 8 columns had shear connecters welded along the centreline of the web, and 8 columns had steel rods welded between the tips of opposing flanges on both sides of the spacing of the transverse link 100 mm and 50 mm. The main parameters studied were: the heel height, and type of connector strengthening. From the test results, it is confirmed that the thin walls are more sensitive to the appearance local buckling and the length of the profiles has a significant effect on the bearing capacity and failure mode. The bearing capacity was increased

  11. PITR: Princeton Ignition Test Reactor

    International Nuclear Information System (INIS)

    The principal objectives of the PITR - Princeton Ignition Test Reactor - are to demonstrate the attainment of thermonuclear ignition in deuterium-tritium, and to develop optimal start-up techniques for plasma heating and current induction, in order to determine the most favorable means of reducing the size and cost of tokamak power reactors. This report describes the status of the plasma and engineering design features of the PITR. The PITR geometry is chosen to provide the highest MHD-stable values of beta in a D-shaped plasma, as well as ease of access for remote handling and neutral-beam injection

  12. Flow Friction or Spontaneous Ignition?

    Science.gov (United States)

    Stoltzfus, Joel M.; Gallus, Timothy D.; Sparks, Kyle

    2012-01-01

    "Flow friction," a proposed ignition mechanism in oxygen systems, has proved elusive in attempts at experimental verification. In this paper, the literature regarding flow friction is reviewed and the experimental verification attempts are briefly discussed. Another ignition mechanism, a form of spontaneous combustion, is proposed as an explanation for at least some of the fire events that have been attributed to flow friction in the literature. In addition, the results of a failure analysis performed at NASA Johnson Space Center White Sands Test Facility are presented, and the observations indicate that spontaneous combustion was the most likely cause of the fire in this 2000 psig (14 MPa) oxygen-enriched system.

  13. PITR: Princeton Ignition Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    1978-12-01

    The principal objectives of the PITR - Princeton Ignition Test Reactor - are to demonstrate the attainment of thermonuclear ignition in deuterium-tritium, and to develop optimal start-up techniques for plasma heating and current induction, in order to determine the most favorable means of reducing the size and cost of tokamak power reactors. This report describes the status of the plasma and engineering design features of the PITR. The PITR geometry is chosen to provide the highest MHD-stable values of beta in a D-shaped plasma, as well as ease of access for remote handling and neutral-beam injection.

  14. Charge transferred in brush discharges

    Science.gov (United States)

    Talarek, M.; Kacprzyk, R.

    2015-10-01

    Electrostatic discharges from surfaces of plastic materials can be a source of ignition, when appear in explosive atmospheres. Incendivity of electrostatic discharges can be estimated using the transferred charge test. In the case of brush discharges not all the energy stored at the tested sample is released and the effective surface charge density (or surface potential) crater is observed after the discharge. Simplified model, enabling calculation of a charge transferred during electrostatic brush discharge, was presented. Comparison of the results obtained from the simplified model and from direct measurements of transferred charge are presented in the paper.

  15. The national ignition facility: path to ignition in the laboratory

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF) is a 192-beam laser facility presently under construction at Lawrence Livermore National Laboratory. When completed, NIF will be a 1.8-MJ, 500-TW ultraviolet laser system. Its missions are to obtain fusion ignition of deuterium-tritium plasmas in ICF (Inertial Confinement Fusion) targets and to perform high energy density experiments in support of the U.S. nuclear weapons stockpile. The NIF facility will consist of 2 laser bays, 4 capacitor areas, 2 laser switchyards, the target area and the building core. The laser is configured in 4 clusters of 48 beams, 2 in each laser bay. Four of the NIF beams have been already commissioned to demonstrate laser performance and to commission the target area including target and beam alignment and laser timing. During this time, NIF has demonstrated on a single-beam basis that it will meet its performance goals and has demonstrated its precision and flexibility for pulse shaping, pointing, timing and beam conditioning. It also performed 4 important experiments for ICF and High Energy Density Science. Presently, the project is installing production hardware to complete the project in 2009 with the goal to begin ignition experiments in 2010. An integrated plan has been developed including the NIF operations, user equipment such as diagnostics and cryogenic target capability, and experiments and calculations to meet this goal. This talk will provide NIF status, the plan to complete NIF, and the path to ignition. (authors)

  16. Confinement of ignition and yield on the National Ignition Facility

    International Nuclear Information System (INIS)

    The National Ignition Facility Target Areas and Experimental Systems has reached mid-Title I design. Performance requirements for the Target Area are reviewed and design changes since the Conceptual Design Report are discussed. Development activities confirm a 5-m radius chamber and the viability of a boron carbide first wall. A scheme for cryogenic target integration with the NIF Target Area is presented

  17. Büroo Ignite = Ignite office / Priit Põldme, Reet Sepp

    Index Scriptorium Estoniae

    Põldme, Priit, 1971-

    2013-01-01

    Büroo Ignite (Tatari 25, Tallinn) sisekujundusest. Sisearhitektid Priit Põldme ja Reet Sepp (SAB Joonprojekt). Arhitektid Heiki Taras ja Ahti Luhaäär (Arhitektibüroo Pilter ja Taras). Sisearhitekti ja ESLi aastapreemiate žürii esimehe Kaido Kivi arvamus

  18. Confinement of ignition and yield on the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, M.; Karpenko, V.; Foley, D.; Anderson, A.; Burnham, A.; Reitz, T.; Latkowski, J.; Bernat, T.

    1996-06-14

    The National Ignition Facility Target Areas and Experimental Systems has reached mid-Title I design. Performance requirements for the Target Area are reviewed and design changes since the Conceptual Design Report are discussed. Development activities confirm a 5-m radius chamber and the viability of a boron carbide first wall. A scheme for cryogenic target integration with the NIF Target Area is presented.

  19. Measurement of reaction-in-flight neutrons using thulium activation at the National Ignition Facility

    Science.gov (United States)

    Grim, G. P.; Rundberg, R.; Fowler, M. M.; Hayes, A. C.; Jungman, G.; Boswell, M.; Klein, A.; Wilhelmy, J.; Tonchev, A.; Yeamans, C. B.

    2014-09-01

    We report on the first observation of tertiary reaction-in-flight (RIF) neutrons produced in compressed deuterium and tritium filled capsules using the National Ignition Facility at Lawrence Livermore National Laboratory, Livermore, CA. RIF neutrons are produced by third-order, out of equilibrium ("in-flight") fusion reactions, initiated by primary fusion products. The rate of RIF reactions is dependent upon the range of the elastically scattered fuel ions and therefore a diagnostic of Coulomb physics within the plasma. At plasma temperatures of ˜5 keV, the presence of neutrons with kinetic energies greater than 15 MeV is a unique signature for RIF neutron production. The reaction 169Tm(n,3n)167Tm has a threshold of 15.0 MeV, and a unique decay scheme making it a suitable diagnostic for observing RIF neutrons. RIF neutron production is quantified by the ratio of 167Tm/168Tm observed in a 169Tm foil, where the reaction 169Tm(n,2n)168Tm samples the primary neutron fluence. Averaged over 4 implosions1-4 at the NIF, the 167Tm/168Tm ratio is measured to be 1.5 +/- 0.3 x 10-5, leading to an average ratio of RIF to primary neutron ratio of 1.0 +/- 0.2 x 10-4. These ratios are consistent with the predictions for charged particle stopping in a quantum degenerate plasma.

  20. Progress in the shock-ignition inertial confinement fusion concept

    Directory of Open Access Journals (Sweden)

    Theobald W.

    2013-11-01

    Full Text Available Shock-ignition experiments with peak laser intensities of ∼8 × 1015 W/cm2 were performed. D2-filled plastic shells were compressed on a low adiabat by 40 of the 60 OMEGA beams. The remaining 20 beams were delayed and tightly focused onto the imploding shell to generate a strong shock. Up to 35% backscattering of laser energy was measured at the highest intensity. Hard x-ray measurements reveal a relatively low hot-electron temperature of ∼40 keV, independent of intensity and spike onset time.

  1. Progress in the shock-ignition inertial confinement fusion concept

    OpenAIRE

    Theobald W.; Casner A.; Nora R.; Ribeyre X.; Lafon M.; Anderson K.S.; Betti R.; Craxton R.S.; Delettrez J.A.; Frenje J.A.; Glebov V.Yu.; Gotchev O.V.; Hohenberger M.; Hu S.X.; Marshall F.J.

    2013-01-01

    Shock-ignition experiments with peak laser intensities of ∼8 × 1015 W/cm2 were performed. D2-filled plastic shells were compressed on a low adiabat by 40 of the 60 OMEGA beams. The remaining 20 beams were delayed and tightly focused onto the imploding shell to generate a strong shock. Up to 35% backscattering of laser energy was measured at the highest intensity. Hard x-ray measurements reveal a relatively low hot-electron temperature of ∼40 keV, independent of intensity and spike onset time....

  2. Progress in the shock-ignition inertial confinement fusion concept

    International Nuclear Information System (INIS)

    Shock-ignition experiments with peak laser intensities of ∼8 x 1015 W/cm2 were performed. D2-filled plastic shells were compressed on a low adiabat by 40 of the 60 OMEGA beams. The remaining 20 beams were delayed and tightly focused onto the imploding shell to generate a strong shock. Up to 35% backscattering of laser energy was measured at the highest intensity. Hard x-ray measurements reveal a relatively low hot-electron temperature of ∼40 keV, independent of intensity and spike onset time. (authors)

  3. Integral low-energy thermite igniter

    Science.gov (United States)

    Gibson, Albert; Haws, Lowell D.; Mohler, Jonathan H.

    1984-08-14

    In a thermite igniter/heat source comprising a container holding an internal igniter load, there is provided the improvement wherein the container consists essentially of consumable consolidated thermite having a low gas output upon combustion, whereby upon ignition, substantially all of the container and said load is consumed with low gas production.

  4. Pyrotechnic Igniters for Liquid Propellant Gun .

    OpenAIRE

    D. K. Kharat; K. J. Daniel; K. R. Rao; A. A. Ghosh; Shah, S.T.; S. C. Mitra

    1997-01-01

    The results of a preliminary investigation on the use of liquid propellant for gun application are presented. Both regenerative and bulk loaded liquid propellant guns were used in the study.Pyrotechnic igniters were tried out for igniting the liquid propellant. Existing pyrotechnic igniters were suitably modified to obtain pressure beyond 20 MPa in less than 3 ms in the combustion chamber.

  5. High-gain inertial confinement fusion by volume ignition, avoiding the complexities of fusion detonation fronts of spark ignition

    International Nuclear Information System (INIS)

    The main approach to Inertial Confinement Fusion (ICF) uses a high-temperature, low-density core and a high-density, low-temperature outer region of the laser- (or ion beam-)compressed deuterium-tritium (D-T) fuel, in order to ignite a fusion detonation wave at the interface. This is an extremely delicate, unstable configuration which is very difficult to achieve, even with a carefully programmed time dependence of the deposition of the driver energy. This approach was devised in order to reach the high gains needed for low-efficiency lasers. Since 1978, several teams have developed an alternative scheme using volume ignition, where a natural and simple adiabatic compression, starting from a low initial temperature of 3 keV or less, is used. The high gains are obtained by self-heating due to the fusion reaction products plus self-absorption of Bremsstrahlung. Fortunately, a strong deviation from LTE occurs at ion temperatures above 100 keV, with much lower electron and even lower radiation temperatures. The authors report here how the gains calculated by different groups are relatively large, and despite detailed differences in the stopping power models, do not differ greatly. The high gain can be explained by introducing an effective value for the density-radius (ρR) product, where the volume ignition process increases the usual value of about 3 g-cm-2 to an effective value of 12 g-cm-2 or more, due to the self-generated additional heating that occurs for beam input energies > MJ and compression over 1,000 times solid state. This result is valid for direct drive as well as for indirect drive

  6. Status of the National Ignition Facility Integrated Computer Control System (ICCS) on the Path to Ignition

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility under construction that will contain a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. NIF is comprised of 24 independent bundles of 8 beams each using laser hardware that is modularized into more than 6,000 line replaceable units such as optical assemblies, laser amplifiers, and multifunction sensor packages containing 60,000 control and diagnostic points. NIF is operated by the large-scale Integrated Computer Control System (ICCS) in an architecture partitioned by bundle and distributed among over 800 front-end processors and 50 supervisory servers. NIF's automated control subsystems are built from a common object-oriented software framework based on CORBA distribution that deploys the software across the computer network and achieves interoperation between different languages and target architectures. A shot automation framework has been deployed during the past year to orchestrate and automate shots performed at the NIF using the ICCS. In December 2006, a full cluster of 48 beams of NIF was fired simultaneously, demonstrating that the independent bundle control system will scale to full scale of 192 beams. At present, 72 beams have been commissioned and have demonstrated 1.4-Megajoule capability of infrared light. During the next two years, the control system will be expanded to include automation of target area systems including final optics, target positioners and

  7. Status of the National Ignition Facility Integrated Computer Control System (ICCS) on the path to ignition

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility under construction that will contain a 192-beam, 1.8-MJ, 500-TW, ultraviolet laser system together with a 10-m diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. NIF is comprised of 24 independent bundles of eight beams each using laser hardware that is modularized into more than 6000 line replaceable units such as optical assemblies, laser amplifiers, and multi-function sensor packages containing 60,000 control and diagnostic points. NIF is operated by the large-scale Integrated Computer Control System (ICCS) in an architecture partitioned by bundle and distributed among over 800 front-end processors and 50 supervisory servers. NIF's automated control subsystems are built from a common object-oriented software framework based on CORBA distribution that deploys the software across the computer network and achieves interoperation between different languages and target architectures. A shot automation framework has been deployed during the past year to orchestrate and automate shots performed at the NIF using the ICCS. In December 2006, a full cluster of 48 beams of NIF was fired simultaneously, demonstrating that the independent bundle control system will scale to full scale of 192 beams. At present, 72 beams have been commissioned and have demonstrated 1.4-MJ capability of infrared light. During the next 2 years, the control system will be expanded in preparation for project completion in 2009 to include automation of target area systems including final optics

  8. Hydrogen and Ethene Plasma Assisted Ignition by NS discharge at Elevated Temperatures

    Science.gov (United States)

    Starikovskiy, Andrey

    2015-09-01

    The kinetics of ignition in lean H2:O2:Ar and C2H4:O2:Ar mixtures has been studied experimentally and numerically after a high-voltage nanosecond discharge. The ignition delay time behind a reflected shock wave was measured with and without the discharge. It was shown that the initiation of the discharge with a specific deposited energy of 10 - 30 mJ/cm3 leads to an order of magnitude decrease in the ignition delay time. Discharge processes and following chain chemical reactions with energy release were simulated. The generation of atoms, radicals and excited and charged particles was numerically simulated using the measured time - resolved discharge current and electric field in the discharge phase. The calculated densities of the active particles were used as input data to simulate plasma-assisted ignition. Good agreement was obtained between the calculated ignition delay times and the experimental data. It follows from the analysis of the calculated results that the main mechanism of the effect of gas discharge on the ignition of hydrocarbons is the electron impact dissociation of O2 molecules in the discharge phase. Detailed kinetic mechanism for plasma assisted ignition of hydrogen and ethene is elaborated and verified.

  9. Investigating the outer-bulb discharge as ignition aid for automotive-HID lamps

    International Nuclear Information System (INIS)

    This work considers the ignition process of mercury-free high-intensity discharge lamps used for car headlights. These lamps have to run-up fast. This is achieved with a high xenon pressure of about 15 bar (cold) in the inner bulb. The high filling-gas pressure causes an increased ignition voltage compared with lower-pressure lamps used in general-lighting applications. In this paper the possibility is investigated to reduce the ignition voltage by optimizing a dielectric-barrier discharge (DBD) in the outer bulb working as ignition aid. A special outer bulb was built up allowing gas exchange and adjustment of the gas pressure. For diagnostic purposes different electrical and optical methods are used, namely the recording of ignition voltage, ignition current and light emission by a photo-diode signal on nanosecond time scale as well as short-time photography by a intensified charge-coupled device camera. It was found that the DBD mainly generates a potential distribution within the lamp which supports ignition by an increase in the E-field in front of the electrodes and the wall. It is shown that this effect is distinctly more effective than UV radiation potentially emitted by the DBD. (paper)

  10. Longitudinal bunch compression study with induction voltage modulator

    OpenAIRE

    Nakayama Akira; Sakai Yasuo; Miyazaki Yoshifumi; Kikuchi Takashi; Nakajima Mitsuo; Horioka Kazuhiko

    2013-01-01

    For the beam driver of inertial confinement fusion, the technology to compress a charged particle beam in longitudinal direction is crucially important. However, the quality of the beam is expected to be deteriorated when the beam is rapidly compressed in longitudinal direction. In order to investigate the beam dynamics during bunch compression, we made a compact beam compression system and carried out beam compression experiments. In this paper, we show the background of our study and recent...

  11. Plasma ignition of LOVA propellants

    NARCIS (Netherlands)

    Driel, C.A. van; Boluijt, A.G.; Schilt, A.

    2010-01-01

    Ignition experiments were performed using a gun simulator which is equipped with a burst disk. This equipment facilitates the application of propellant loading densities which are comparable to those applied in regular ammunitions. For this study the gun simulator was equipped with a plasma jet igni

  12. Concept of laser fusion power plant based on fast ignition

    International Nuclear Information System (INIS)

    This paper introduces new concept of laser fusion that is expected to demonstrate energy generation based on inertial fusion in the near future. In the fast ignition (FI) scheme, a spherical hollow solid deuterium-tritium fuel is compressed to a high density of 1000 times solid density with tens nano-second laser pulses from a compression laser and the compressed fuel core is directly heated to 5 keV with a ten pico-second laser pulse from a heating laser. This FI scheme enables us to design an IFE power plant with a 1MJ-class, compact laser whose output energy is 1/4 of previous central ignition scheme. Recent progress on cooled Yb-YAG ceramic laser revealed that highly efficient compression and heating lasers can be constructed using this laser material with acceptable construction cost including laser diodes for pumping and the refrigerator. New reactor scheme for a liquid wall reactor that has no stagnation point of ablated gas and a rotary shutter system to protect the final optics are proposed. Current computer simulation indicates thermonuclear gain of 160 will be achieved with 1.1 MJ / 10 ns compression lasers and a 100 kJ/10 ps heating laser. A diode-pumped, cooled, Yb-YAG ceramic-laser is the prior candidate for the compression laser operated at 16 Hz rep rate. The conversion efficiencies from electricity to laser are 9.5% for the compression laser, 3.5% for the heating laser, and 6.9% in total including cooling power, respectively. The power plant consists of 4 module reactors powered by one laser system. One module reactor has 32 compression beams, one heating laser, and two target injectors as shown. Each beam port has a rotary shutter and an electro magnet to prevent the final optics from neutral vapor and ions, respectively. The panels of the first wall are tilted by 30 degree to avoid stagnation of evaporated vapor at the chamber center. The focus position is vertically off set to simplify the protection mechanism of the ceiling. (author)

  13. Laser ignition application in a space experiment

    Science.gov (United States)

    Liou, Larry C.; Culley, Dennis E.

    1993-01-01

    A laser ignition system is proposed for the Combustion Experiment Module on an orbiting spacecraft. The results of a design study are given using the scheduled 'Flame Ball Experiment' as the design guidelines. Three laser ignition mechanisms and wavelengths are evaluated. A prototype laser is chosen and its specifications are given, followed by consideration of the beam optical arrangement, the ignition power requirement, the laser ignition system weight, size, reliability, and laser cooling and power consumption. Electromagnetic interference to the onboard electronics caused by the laser ignition process is discussed. Finally, ground tests are suggested.

  14. Research of laser ignition detection system

    Science.gov (United States)

    Yang, Feng; Zhao, Dong; Xu, Qie; Ai, Xin

    2010-10-01

    Laser ignition is an important means of detonation but the accuracy and security is requested strictly. Based on the above, two points were considered in the design: achieve ignition-Fiber-optical health monitoring in the condition of low-intensity light (ensure the safety of gunpowder); observant the explosive imaging. In the paper, the laser ignition equipment was designed with optical detection and inner optical imaging system for the real-time monitoring to the optical fiber and the process of ignition. This design greatly improved the reliability and the safety of laser ignition system and provided the guarantee for usage and industrialization.

  15. Ignition of alkane-rich FACE gasoline fuels and their surrogate mixtures

    KAUST Repository

    Sarathy, Mani

    2015-01-01

    Petroleum derived gasoline is the most used transportation fuel for light-duty vehicles. In order to better understand gasoline combustion, this study investigated the ignition propensity of two alkane-rich FACE (Fuels for Advanced Combustion Engines) gasoline test fuels and their corresponding PRF (primary reference fuel) blend in fundamental combustion experiments. Shock tube ignition delay times were measured in two separate facilities at pressures of 10, 20, and 40 bar, temperatures from 715 to 1500 K, and two equivalence ratios. Rapid compression machine ignition delay times were measured for fuel/air mixtures at pressures of 20 and 40 bar, temperatures from 632 to 745 K, and two equivalence ratios. Detailed hydrocarbon analysis was also performed on the FACE gasoline fuels, and the results were used to formulate multi-component gasoline surrogate mixtures. Detailed chemical kinetic modeling results are presented herein to provide insights into the relevance of utilizing PRF and multi-component surrogate mixtures to reproduce the ignition behavior of the alkane-rich FACE gasoline fuels. The two FACE gasoline fuels and their corresponding PRF mixture displayed similar ignition behavior at intermediate and high temperatures, but differences were observed at low temperatures. These trends were mimicked by corresponding surrogate mixture models, except for the amount of heat release in the first stage of a two-stage ignition events, when observed. © 2014 The Combustion Institute.

  16. Inertial Confinement Fusion: steady progress towards ignition and high gain (summary talk)

    International Nuclear Information System (INIS)

    Most important recent advances in inertial confinement fusion (ICF) are highlighted. With the construction of the NIF and LMJ facilities, and a number of improvements in the target design, the conventional indirect-drive approach is making a steady progress towards demonstration of ignition and high gain. The development of the polar direct-drive concept made also the prospects for direct-drive ignition on the NIF extremely favorable. A substantial progress has been reported from the Institute of Laser Engineering in Osaka on exploration of the fast-ignition approach to ICF. Parallel to that, multi-wire Z-pinches have become a competitive driver option for achieving ignition at a lowest possible cost. In heavy ion fusion, experiments have been devoted so far to studying the generation, transport, and final focusing of high-current ion beams. A new concept for a power plant with a heavy-ion driver, based on a cylindrical direct-drive target compressed and ignited (in the fast-ignition mode) by two separate beams of very energetic (Ei > or ∼ 0.5 GeV/u) heavy ions, has been proposed. (author)

  17. [Compression material].

    Science.gov (United States)

    Perceau, Géraldine; Faure, Christine

    2012-01-01

    The compression of a venous ulcer is carried out with the use of bandages, and for less exudative ulcers, with socks, stockings or tights. The system of bandages is complex. Different forms of extension and therefore different types of models exist. PMID:22489428

  18. Wellhead compression

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, Joe [Sertco Industries, Inc., Okemah, OK (United States); Vazquez, Daniel [Hoerbiger Service Latin America Inc., Deerfield Beach, FL (United States); Jacobs, Denis Richard [Hoerbiger do Brasil Industria de Equipamentos, Cajamar, SP (Brazil)

    2012-07-01

    Over time, all wells experience a natural decline in oil and gas production. In gas wells, the major problems are liquid loading and low downhole differential pressures which negatively impact total gas production. As a form of artificial lift, wellhead compressors help reduce the tubing pressure resulting in gas velocities above the critical velocity needed to surface water, oil and condensate regaining lost production and increasing recoverable reserves. Best results come from reservoirs with high porosity, high permeability, high initial flow rates, low decline rates and high total cumulative production. In oil wells, excessive annulus gas pressure tends to inhibit both oil and gas production. Wellhead compression packages can provide a cost effective solution to these problems by reducing the system pressure in the tubing or annulus, allowing for an immediate increase in production rates. Wells furthest from the gathering compressor typically benefit the most from wellhead compression due to system pressure drops. Downstream compressors also benefit from higher suction pressures reducing overall compression horsepower requirements. Special care must be taken in selecting the best equipment for these applications. The successful implementation of wellhead compression from an economical standpoint hinges on the testing, installation and operation of the equipment. Key challenges and suggested equipment features designed to combat those challenges and successful case histories throughout Latin America are discussed below.(author)

  19. Laser-plasma interaction physics for shock ignition

    Directory of Open Access Journals (Sweden)

    Goyon C.

    2013-11-01

    Full Text Available In the shock ignition scheme, the ICF target is first compressed with a long (nanosecond pulse before creating a convergent shock with a short (∼100 ps pulse to ignite thermonuclear reactions. This short pulse is typically (∼2.1015–1016 W/cm2 above LPI (Laser Plasma Instabilities thresholds. The plasma is in a regime where the electron temperature is expected to be very high (2–4 keV and the laser coupling to the plasma is not well understood. Emulating LPI in the corona requires large and hot plasmas produced by high-energy lasers. We conducted experiments on the LIL (Ligne d'Integration Laser, 10 kJ at 3ω and the LULI2000 (0.4 kJ at 2ω facilities, to approach these conditions and study absorption and LPI produced by a high intensity beam in preformed plasmas. After introducing the main risks associated with the short pulse propagation, we present the latest experiment we conducted on LPI in relevant conditions for shock ignition.

  20. Ignition timing advance in the bi-fuel engine

    Directory of Open Access Journals (Sweden)

    Marek FLEKIEWICZ

    2009-01-01

    Full Text Available The influence of ignition timing on CNG combustion process has been presented in this paper. A 1.6 liter SI engine has been tested in the special program. For selected engine operating conditions, following data were acquired: in cylinder pressure, crank angle, fuel mass consumption and exhaust gases temperatures. For the timing advance correction varying between 0 to 15 deg crank angle, the internal temperature of combustion chamber, as well as the charge combustion ratio and ratio of heat release has been estimated. With the help of the mathematical model, emissions of NO, CO and CO2 were additionally estimated. Obtained results made it possible to compare the influence of ignition timing advance on natural gas combustion in the SI engine. The engine torque and in-cylinder pressure were used for determination of the optimum engine timing advance.

  1. Experiment in planar geometry for shock ignition studies.

    Science.gov (United States)

    Baton, S D; Koenig, M; Brambrink, E; Schlenvoigt, H P; Rousseaux, C; Debras, G; Laffite, S; Loiseau, P; Philippe, F; Ribeyre, X; Schurtz, G

    2012-05-11

    The capacity to launch a strong shock wave in a compressed target in the presence of large preplasma has been investigated experimentally and numerically in a planar geometry. The experiment was performed on the LULI 2000 laser facility using one laser beam to compress the target and a second to launch the strong shock simulating the intensity spike in the shock ignition scheme. Thanks to a large set of diagnostics, it has been possible to compare accurately experimental results with 2D numerical simulations. A good agreement has been observed even if a more detailed study of the laser-plasma interaction for the spike is necessary in order to confirm that this scheme is a possible alternative for inertial confinement fusion. PMID:23003050

  2. Experiment in Planar Geometry for Shock Ignition Studies

    Science.gov (United States)

    Baton, S. D.; Koenig, M.; Brambrink, E.; Schlenvoigt, H. P.; Rousseaux, C.; Debras, G.; Laffite, S.; Loiseau, P.; Philippe, F.; Ribeyre, X.; Schurtz, G.

    2012-05-01

    The capacity to launch a strong shock wave in a compressed target in the presence of large preplasma has been investigated experimentally and numerically in a planar geometry. The experiment was performed on the LULI 2000 laser facility using one laser beam to compress the target and a second to launch the strong shock simulating the intensity spike in the shock ignition scheme. Thanks to a large set of diagnostics, it has been possible to compare accurately experimental results with 2D numerical simulations. A good agreement has been observed even if a more detailed study of the laser-plasma interaction for the spike is necessary in order to confirm that this scheme is a possible alternative for inertial confinement fusion.

  3. ARDENT ignites research careers

    CERN Multimedia

    Antonella Del Rosso

    2013-01-01

    The ARDENT (Advanced Radiation Dosimetry European Network Training) project passed its mid-term review exercise with flying colours. At the recent workshop at the Politecnico of Milan, the ARDENT researchers again took full advantage of the networking and training opportunities offered by the project.   “The EU officer and the accompanying expert from the Norwegian Research Council congratulated us on the work done and the progress we are making with the programme,” says CERN’s Marco Silari, ARDENT scientist-in-charge. “All the researchers involved in ARDENT presented their work and we were able to confirm that we are keeping on schedule and delivering the expected results. In some cases, the research programme has even been extended to include new research developments.” An example is the GEMPIX detector, a sensor for radiation detection that uses a Gas Electron Multiplier (GEM) gaseous detector with a MediPix read-out system. “GEM...

  4. Laser-plasma interactions for fast ignition

    Science.gov (United States)

    Kemp, A. J.; Fiuza, F.; Debayle, A.; Johzaki, T.; Mori, W. B.; Patel, P. K.; Sentoku, Y.; Silva, L. O.

    2014-05-01

    In the electron-driven fast-ignition (FI) approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser-plasma interactions (LPI) relevant to FI. Increases in computational and modelling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multi-dimensional particle-in-cell simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of laser absorption fraction, the laser-generated electron spectra, divergence, and their temporal evolution. Scaling with irradiation conditions such as laser intensity are considered, as well as the dependence on plasma parameters. Different numerical modelling approaches and configurations are addressed, providing an overview of the modelling capabilities and limitations. In addition, we discuss the comparison of simulation results with experimental observables. In particular, we address the question of surrogacy of today's experiments for the full-scale FI problem.

  5. Laser–plasma interactions for fast ignition

    International Nuclear Information System (INIS)

    In the electron-driven fast-ignition (FI) approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser–plasma interactions (LPI) relevant to FI. Increases in computational and modelling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multi-dimensional particle-in-cell simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of laser absorption fraction, the laser-generated electron spectra, divergence, and their temporal evolution. Scaling with irradiation conditions such as laser intensity are considered, as well as the dependence on plasma parameters. Different numerical modelling approaches and configurations are addressed, providing an overview of the modelling capabilities and limitations. In addition, we discuss the comparison of simulation results with experimental observables. In particular, we address the question of surrogacy of today's experiments for the full-scale FI problem. (special topic)

  6. Tritium and ignition target management at the National Ignition Facility.

    Science.gov (United States)

    Draggoo, Vaughn

    2013-06-01

    Isotopic mixtures of hydrogen constitute the basic fuel for fusion targets of the National Ignition Facility (NIF). A typical NIF fusion target shot requires approximately 0.5 mmoles of hydrogen gas and as much as 750 GBq (20 Ci) of 3H. Isotopic mix ratios are specified according to the experimental shot/test plan and the associated test objectives. The hydrogen isotopic concentrations, absolute amounts, gas purity, configuration of the target, and the physical configuration of the NIF facility are all parameters and conditions that must be managed to ensure the quality and safety of operations. An essential and key step in the preparation of an ignition target is the formation of a ~60 μm thick hydrogen "ice" layer on the inner surface of the target capsule. The Cryogenic Target Positioning System (Cryo-Tarpos) provides gas handling, cyro-cooling, x-ray imaging systems, and related instrumentation to control the volumes and temperatures of the multiphase (solid, liquid, and gas) hydrogen as the gas is condensed to liquid, admitted to the capsule, and frozen as a single spherical crystal of hydrogen in the capsule. The hydrogen fuel gas is prepared in discrete 1.7 cc aliquots in the LLNL Tritium Facility for each ignition shot. Post-shot hydrogen gas is recovered in the NIF Tritium Processing System (TPS). Gas handling systems, instrumentation and analytic equipment, material accounting information systems, and the shot planning systems must work together to ensure that operational and safety requirements are met. PMID:23629062

  7. Ion Fast Ignition-Establishing a Scientific Basis for Inertial Fusion Energy --- Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Richard Burnite [General Atomics; Foord, Mark N. [Lawrence Livermore National Laboratory; Wei, Mingsheng [General Atomics; Beg, Farhat N. [University of California, San Diego; Schumacher, Douglass W. [The Ohio State University

    2013-10-31

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional ?central hot spot? (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10?s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The compressed fuel is opaque to laser light. The ignition laser energy must be converted to a jet of energetic charged particles to deposit energy in the dense fuel. The original concept called for a spray of laser-generated hot electrons to deliver the energy; lack of ability to focus the electrons put great weight on minimizing the electron path. An alternative concept, proton-ignited FI, used those electrons as intermediaries to create a jet of protons that could be focused to the ignition spot from a more convenient distance. Our program focused on the generation and directing of the proton jet, and its transport toward the fuel, none of which were well understood at the onset of our program. We have developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to create a self-consistent understanding of the fundamental physics underlying these issues. Our strategy was to examine the new physics emerging as we added the complexity necessary to use proton beams in an inertial fusion energy (IFE) application. From the starting point of a proton beam accelerated from a flat, isolated foil, we 1) curved it to focus the beam, 2) attached the foil to a superstructure, 3) added a side sheath to protect it from the surrounding plasma, and finally 4) studied the proton beam behavior as it passed through a protective end cap into plasma. We built up, as we proceeded

  8. Observation of strong electromagnetic fields around laser-entrance holes of ignition-scale hohlraums in inertial-confinement fusion experiments at the National Ignition Facility

    OpenAIRE

    C. K. Li; Zylstra, Alex Bennett; Frenje, Johan A.; Seguin, Fredrick Hampton; Sinenian, Nareg; Petrasso, Richard D.; Amendt, P. A.; Bionta, R.; Friedrich, S.; Collins, G. W.; Dewald, E. L.; Doppner, T.; Glenzer, S. H.; Hicks, D. G.; Landen, O. L.

    2012-01-01

    Energy spectra and spectrally resolved one-dimensional fluence images of self-emitted charged-fusion products (14.7 MeV D[superscript 3]He protons) are routinely measured from indirectly driven inertial-confinement fusion (ICF) experiments utilizing ignition-scaled hohlraums at the National Ignition Facility (NIF). A striking and consistent feature of these images is that the fluence of protons leaving the ICF target in the direction of the hohlraum's laser entrance holes (LEHs) is very nonun...

  9. Piezoelectric Ignition of Nanocomposite Energetic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Eric Collins; Michelle Pantoya; Andreas A. Neuber; Michael Daniels; Daniel Prentice

    2014-01-01

    Piezoelectric initiators are a unique form of ignition for energetic material because the current and voltage are tied together by impact loading on the crystal. This study examines the ignition response of an energetic composite composed of aluminum and molybdenum trioxide nanopowders to the arc generated from a lead zirconate and lead titanate piezocrystal. The mechanical stimuli used to activate the piezocrystal varied to assess ignition voltage, power, and delay time of aluminum–molybdenum trioxide for a range of bulk powder densities. Results show a high dielectric strength leads to faster ignition times because of the higher voltage delivered to the energetic. Ignition delay is under 0.4 ms, which is faster than observed with thermal or shock ignition. Electric ignition of composite energetic materials is a strong function of interparticle connectivity, and thus the role of bulk density on electrostatic discharge ignition sensitivity is a focus of this study. Results show that the ignition delay times are dependent on the powder bulk density with an optimum bulk density of 50%. Packing fractions and electrical conductivity were analyzed and aid in explaining the resulting ignition behavior as a function of bulk density.

  10. Status of the National Ignition Facility and Campaign, and Controls and Information Systems on the Path to Ignition

    Energy Technology Data Exchange (ETDEWEB)

    Lagin, L.; Azevedo, S.; Bettenhausen, R.; Beeler, R.; Belk, L.; Bowers, G.; Brunton, G.; Carey, R.; Casey, A.; Christensen, M.; Demaret, R.; Edwards, O.; Estes, C.; Fisher, J.; Foxworthy, C.; Frazier, T.; Kegelmeyer, L.; Krammen, J.; Ludwigsen, A.; Mathisen, D.; Marshall, C.; Shelton, R.; Stout, E.; Townsend, S.; Van Arsdall, P.; Wilson, E. [Lawrence Livermore National Laboratory, Livermore (United States)

    2009-07-01

    Full text of the publication follows: The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility under construction that will contain a 192-beam, 1.8-Mega-joule, 500-Terawatt, ultraviolet laser system together with a 10- meter diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. NIF is operated by the large-scale Integrated Computer Control System (ICCS) in an architecture partitioned by bundle and distributed among over 1000 front-end processors, embedded controllers and supervisory servers. NIF's automated control subsystems are built from a common object-oriented software framework based on CORBA distribution that deploys the software across the computer network and achieves inter-operation between different languages and target architectures. A shot automation framework has been used to orchestrate and automate over a thousand system shots performed at the NIF using the ICCS. An experimental database and automated shot analysis infrastructure has also been developed and is being used for conducting experiments. In March 2009, the NIF project was completed by successfully demonstrating its formal completion of performance and operational design criteria. At present, all 192 beams have been commissioned to target chamber center. During the past year, the control system was expanded to include automation of target area systems including final optics, target positioners and diagnostics, in preparation for project completion. A detailed set of experiments have begun and are being performed as part of a National

  11. Status of the National Ignition Facility and Campaign, and Controls and Information Systems on the Path to Ignition

    International Nuclear Information System (INIS)

    Full text of publication follows: The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility under construction that will contain a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10- meter diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. NIF is operated by the large-scale Integrated Computer Control System (ICCS) in an architecture partitioned by bundle and distributed among over 1000 front-end processors, embedded controllers and supervisory servers. NIF's automated control subsystems are built from a common object-oriented software framework based on CORBA distribution that deploys the software across the computer network and achieves inter-operation between different languages and target architectures. A shot automation framework has been used to orchestrate and automate over a thousand system shots performed at the NIF using the ICCS. An experimental database and automated shot analysis infrastructure has also been developed and is being used for conducting experiments. In March 2009, the NIF project was completed by successfully demonstrating its formal completion of performance and operational design criteria. At present, all 192 beams have been commissioned to target chamber center. During the past year, the control system was expanded to include automation of target area systems including final optics, target positioners and diagnostics, in preparation for project completion. A detailed set of experiments have begun and are being performed as part of a National Ignition Campaign

  12. Magnetically Guided Fast Electrons in Cylindrically Compressed Matter

    International Nuclear Information System (INIS)

    Fast electrons produced by a 10 ps, 160 J laser pulse through laser-compressed plastic cylinders are studied experimentally and numerically in the context of fast ignition. Kα-emission images reveal a collimated or scattered electron beam depending on the initial density and the compression timing. A numerical transport model shows that implosion-driven electrical resistivity gradients induce strong magnetic fields able to guide the electrons. The good agreement with measured beam sizes provides the first experimental evidence for fast-electron magnetic collimation in laser-compressed matter.

  13. A new ignition scheme using hybrid indirect-direct drive for inertial confinement fusion

    CERN Document Server

    Fan, Zhengfeng; Dai, Zhensheng; Cai, Hong-bo; Zhu, Shao-ping; Zhang, W Y; He, X T

    2013-01-01

    A new hybrid indirect-direct-drive ignition scheme is proposed for inertial confinement fusion: a cryogenic capsule encased in a hohlraum is first compressed symmetrically by indirect-drive x-rays, and then accelerated and ignited by both direct-drive lasers and x-rays. A steady high-density plateau newly formed between the radiation and electron ablation fronts suppresses the rarefaction at the radiation ablation front and greatly enhances the drive pressure. Meanwhile, multiple shock reflections at the fuel/hot-spot interface are prevented during capsule deceleration. Thus rapid ignition and burn are realized. In comparison with the conventional indirect drive, the hybrid drive implodes the capsule with a higher velocity ($\\sim4.3\\times10^7$ cm/s) and a much lower convergence ratio ($\\sim$25), and the growth of hydrodynamic instabilities is significantly reduced, especially at the fuel/hot-spot interface.

  14. Conceptual design of laser fusion reactor KOYO-F based on fast ignition scheme

    International Nuclear Information System (INIS)

    Recent progress on fast ignition (FI) enables us to design an IFE power plant with a 1MJ-class, compact laser whose output energy is 1/4 of previous central ignition scheme. Basing on the FI scheme, we conceptually designed a laser fusion power plant driven with cooled-Yb:YAG, ceramic lasers. In this design activity, we newly evaluated the gain curve for FI basing on latest simulation code. Cooled Yb-YAG ceramic was newly chosen as the laser material. We found that the heating laser for ignition could be constructed with the cooled Yb:YAG ceramics as well as the compression laser with acceptable electricity-laser conversion efficiencies including the electric power for the cooling system. New reactor scheme for a liquid wall reactor that has no stagnation point of ablated gas and a rotary shutter system to protect the final optics are proposed. (author)

  15. A sustained-arc ignition system for internal combustion engines

    Science.gov (United States)

    Birchenough, A. G.

    1977-01-01

    A sustained-arc ignition system was developed for internal combustion engines. It produces a very-long-duration ignition pulse with an energy in the order of 100 millijoules. The ignition pulse waveform can be controlled to predetermined actual ignition requirements. The design of the sustained-arc ignition system is presented in the report.

  16. Ignition of hydrogen/oxygen/nitrogen mixtures exposed to two configuration dependent ignition sources

    International Nuclear Information System (INIS)

    White Sands Test Facility performed a series of tests to determine the ignition characteristic of hydrogen/oxygen/nitrogen mixtures. The testing was performed to assess the ignition hazard on board the Space Transportation System (STS) from possible leakage of hydrogen, oxygen and nitrogen. The ignition sources consisted of an exhaust duct that exposed a heated surface through a 1/4 inch crack in the insulation and a heated surface that existed at the bottom of a 0.75-inch diameter, 2-inch long tube. These ignition sources were fabricated to simulate the exhaust duct and the hydrazine injector tube in the auxiliary power unit on board the STS. The data obtained using these ignition sources were compared with data obtained using common ignition sources such as electrical spark, hot surfaces, etc. The results indicated that the configuration aspects of the ignition source had significant affects on the ignition characteristics of hydrogen mixtures

  17. The insulation irradiation test program for the Compact Ignition Tokamak

    International Nuclear Information System (INIS)

    The electrical insulation for the toroidal field coils of the Compact Ignition Tokamak (CIT) is expected to be exposed to radiation doses on the order of 1010 rad with ∼90% of the dose from neutrons. The coils are cooled to liquid nitrogen temperature and then heated during the pulse to a peak temperature >300 K. In a program to evaluate the effects of radiation exposure on the insulators, three types of boron-free insulation were irradiated at room temperature in the Advanced Technology Reactor (ATR) and tested at the Idaho National Engineering Laboratory. The materials were Spaulrad-S, Shikishima PG5-1, and Shikishima PG3-1. The first two use a bismaleimide resin and the third an aromatic amine hardened epoxy. Spaulrad-S is a two-dimensional (2-D) weave of S-glass, while the others are 3-D weaves of T-glass. Flexure and shear/compression samples were irradiated to approximately 5 x 109 rad and 3 x 1010 rad with 35 to 40% of the total dose from neutrons. The shear/compression samples were tested in pairs by applying an average compression of 345 MPa and then a shear load. After static tests were completed, fatigue testing was done by cycling the shear load for up to 30,000 cycles with a constant compression. The static shear strength of the samples that did not fail was then determined. Generally, shear strengths on the order of 120 MPa were measured. The behavior of the flexure and shear/compression samples was significantly different; large reductions in the flexure strength were observed, while the shear strength stayed the same or increased slightly. The 3-D weave material demonstrated higher strength and significantly less radiation damage than the 2-D material in flexure but performed nearly identically when tested with combined shear and compression. The epoxy system was much more sensitive to fatigue damage than the bismaleimide materials. 9 refs., 5 figs

  18. Insulation irradiation test programme for the Compact Ignition Tokamak

    International Nuclear Information System (INIS)

    In a programme to evaluate the effects of radiation exposure on the electrical insulation for the toroidal field coils of the Compact Ignition Tokamak, three types of boron-free insulation were irradiated at room temperature in the Advanced Technology Reactor (ATR) and tested at the Idaho National Engineering Laboratory. The materials were Spaulrad-S, Shikishima PG5-1 and Shikishima PG3-1. The first two use a bismaleimide resin and the third an aromatic amine hardened epoxy. Spaulrad-S is a two-dimensional (2-D) weave of S-glass, while the others are 3-D weaves of T-glass. Flexure and shear/compression samples were irradiated to ≅ 5 x 109 and 3 x 1010 rad with 35-40% of the total dose from neutrons. The shear/compression samples were tested in pairs by applying an average compression of 345 MPa and then a shear load. After static tests were completed, fatigue testing was performed by cycling the shear load for up to 30000 cycles with a constant compression. The static shear strength of the samples that did not fail was then determined. Generally, shear strengths of the order of 120 MPa were measured. The behaviour of the flexure and shear/compression samples was significantly different; large reductions in the flexure strength were observed, while the shear strength stayed the same or increased slightly. The 3-D weave material demonstrated higher strength and significantly less radiation damage than the 2-D material in flexure but performed almost identically when tested with combined shear and compression. The epoxy system was much more sensitive to fatigue damage than the bismaleimide materials. No swelling was measured; however, the epoxy samples did twist slightly. (author)

  19. Studies into laser ignition of confined pyrotechnics

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S.R.; Russell, D.A. [Centre for Applied Laser Spectroscopy, DASSR, Defence Academy, Cranfield University, Shrivenham, Swindon (United Kingdom)

    2008-10-15

    Ignition tests were carried out on three different pyrotechnics using laser energy from the multimode output from an Ar-Ion laser (av) at 500 nm and a near-IR diode laser pigtailed to a fibre optic cable and operating at 808 nm. The pyrotechnics investigated were: G20 black powder, SR44 and SR371C. The confined ignition tests were conducted in a specially designed ignition chamber. Pyrotechnics were ignited by a free space beam entering the chamber through an industrial sapphire window in the case of the Ar-ion laser. For the NIR diode laser, fibre was ducted through a block into direct contact with the pyrotechnic. The Ar-Ion laser was chosen as this was found to ignite all three pyrotechnics in the unconfined condition. It also allowed for a direct comparison of confined/unconfined results to be made. The threshold laser flux densities to initiate reproducible ignitions at this wavelength were found to be between {proportional_to}12.7 and {proportional_to}0.16 kW cm{sup -2}. Plotted on the ignition maps are the laser flux densities versus the start of ignition times for the three confined pyrotechnics. It was found from these maps that the times for confined ignition were substantially lower than those obtained for unconfined ignition under similar experimental conditions. For the NIR diode laser flux densities varied between {proportional_to}6.8 and {proportional_to}0.2 kW cm{sup -2}. The minimum ignition times for the NIR diode laser for SR371C ({proportional_to}11.2 ms) and G20 ({proportional_to}17.1 ms) were faster than those achieved by the use of the Ar-ion laser. However, the minimum ignition time was shorter ({proportional_to}11.7 ms) with the Ar-ion laser for SR44. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  20. Pyrotechnic Igniters for Liquid Propellant Gun .

    Directory of Open Access Journals (Sweden)

    D. K. Kharat

    1997-04-01

    Full Text Available The results of a preliminary investigation on the use of liquid propellant for gun application are presented. Both regenerative and bulk loaded liquid propellant guns were used in the study.Pyrotechnic igniters were tried out for igniting the liquid propellant. Existing pyrotechnic igniters were suitably modified to obtain pressure beyond 20 MPa in less than 3 ms in the combustion chamber.

  1. Compressive beamforming

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Mosegaard, Klaus

    2014-01-01

    Sound source localization with sensor arrays involves the estimation of the direction-of-arrival (DOA) from a limited number of observations. Compressive sensing (CS) solves such underdetermined problems achieving sparsity, thus improved resolution, and can be solved efficiently with convex...... optimization. The DOA estimation problem is formulated in the CS framework and it is shown that CS has superior performance compared to traditional DOA estimation methods especially under challenging scenarios such as coherent arrivals and single-snapshot data. An offset and resolution analysis is performed to...

  2. Analysis of the National Ignition Facility ignition hohlraum energetics experiments

    International Nuclear Information System (INIS)

    A series of 40 experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] to study energy balance and implosion symmetry in reduced- and full-scale ignition hohlraums was shot at energies up to 1.3 MJ. This paper reports the findings of the analysis of the ensemble of experimental data obtained that has produced an improved model for simulating ignition hohlraums. Last year the first observation in a NIF hohlraum of energy transfer between cones of beams as a function of wavelength shift between those cones was reported [P. Michel et al., Phys. Plasmas 17, 056305 (2010)]. Detailed analysis of hohlraum wall emission as measured through the laser entrance hole (LEH) has allowed the amount of energy transferred versus wavelength shift to be quantified. The change in outer beam brightness is found to be quantitatively consistent with LASNEX [G. B. Zimmerman and W. L. Kruer, Comments Plasma Phys. Controlled Fusion 2, 51 (1975)] simulations using the predicted energy transfer when possible saturation of the plasma wave mediating the transfer is included. The effect of the predicted energy transfer on implosion symmetry is also found to be in good agreement with gated x-ray framing camera images. Hohlraum energy balance, as measured by x-ray power escaping the LEH, is quantitatively consistent with revised estimates of backscatter and incident laser energy combined with a more rigorous non-local-thermodynamic-equilibrium atomic physics model with greater emissivity than the simpler average-atom model used in the original design of NIF targets.

  3. Lateral Ignition and Flame Spread Apparatus

    Data.gov (United States)

    Federal Laboratory Consortium — Description: This apparatus, developed at EL, determines material properties related to piloted ignition of a vertically oriented sample under constant and uniform...

  4. Modelling piloted ignition of wood and plastics

    International Nuclear Information System (INIS)

    Highlights: ► We model piloted ignition times of wood and plastics. ► The model is applied on a packed bed. ► When the air flow is above a critical level, no ignition can take place. - Abstract: To gain insight in the startup of an incinerator, this article deals with piloted ignition. A newly developed model is described to predict the piloted ignition times of wood, PMMA and PVC. The model is based on the lower flammability limit and the adiabatic flame temperature at this limit. The incoming radiative heat flux, sample thickness and moisture content are some of the used variables. Not only the ignition time can be calculated with the model, but also the mass flux and surface temperature at ignition. The ignition times for softwoods and PMMA are mainly under-predicted. For hardwoods and PVC the predicted ignition times agree well with experimental results. Due to a significant scatter in the experimental data the mass flux and surface temperature calculated with the model are hard to validate. The model is applied on the startup of a municipal waste incineration plant. For this process a maximum allowable primary air flow is derived. When the primary air flow is above this maximum air flow, no ignition can be obtained.

  5. Spontaneously Igniting Hybrid Fuel-Oxidiser Systems

    OpenAIRE

    Jain, S. R.

    1995-01-01

    After briefly outlining the recent developments in hybrid rockets, the work carried out by the author on self-igniting (hypergolic) solid fuel-liquid oxidiser systems has been reviewed. A major aspect relates to the solid derivatives of hydrazines, which have been conceived as fuels for hybrid rockets. Many of these N-N bonded compounds ignite readily, with very short ignition delays, on coming into contact with liquid oxidisers, like HNO/sub 3/ and N/sub 2/ O/sub 4/. The ignition char...

  6. Muon catalyzed fusion under compressive conditions

    International Nuclear Information System (INIS)

    The viability of a symbiotic combination of Muon Catalyzed Fusion (μCF) and high density generation processes has been investigated. The muon catalyzed fusion reaction rates are formulated in the temperature and density range found under moderate compressive conditions. Simplified energy gain and power balance calculations indicate that significant energy gain occurs only if standard type deuterium-tritium (dt) fusion is ignited. A computer simulation of the hydrodynamics and fusion kinetics of a spherical deuterium-tritium pellet implosion including muons is performed. Using the muon catalyzed fusion reaction rates formulated and under ideal conditions, the pellet ignites (and thus has a significant energy gain) only if the initial muon concentration is approximately 1017 cm-3. The muons need to be delivered to the pellet within a very short-time (≅ 1 ns). The muon pulse required in order to make the high density and temperature muon catalyzed fusion scheme viable is beyond the present technology for muon production. (orig.)

  7. Compressed convolution

    CERN Document Server

    Elsner, F

    2013-01-01

    We introduce the concept of compressed convolution, a technique to convolve a given data set with a large number of non-orthogonal kernels. In typical applications our technique drastically reduces the effective number of computations. The new method is applicable to convolutions with symmetric and asymmetric kernels and can be easily controlled for an optimal trade-off between speed and accuracy. It is based on linear compression of the collection of kernels into a small number of coefficients in an optimal eigenbasis. The final result can then be decompressed in constant time for each desired convolved output. The method is fully general and suitable for a wide variety of problems. We give explicit examples in the context of simulation challenges for upcoming multi-kilo-detector cosmic microwave background (CMB) missions. For a CMB experiment with O(10,000) detectors with similar beam properties, we demonstrate that the algorithm can decrease the costs of beam convolution by two to three orders of magnitude...

  8. Characteristics of Syngas Auto-ignition at High Pressure and Low Temperature Conditions with Thermal Inhomogeneities

    KAUST Repository

    Pal, Pinaki

    2015-05-31

    Effects of thermal inhomogeneities on syngas auto-ignition at high-pressure low-temperature conditions, relevant to gas turbine operation, are investigated using detailed one-dimensional numerical simulations. Parametric tests are carried out for a range of thermodynamic conditions (T = 890-1100 K, P = 3-20 atm) and composition (Ф = 0.1, 0.5). Effects of global thermal gradients and localized thermal hot spots are studied. In the presence of a thermal gradient, the propagating reaction front transitions from spontaneous ignition to deflagration mode as the initial mean temperature decreases. The critical mean temperature separating the two distinct auto-ignition modes is computed using a predictive criterion and found to be consistent with front speed and Damkohler number analyses. The hot spot study reveals that compression heating of end-gas mixture by the propagating front is more pronounced at lower mean temperatures, significantly advancing the ignition delay. Moreover, the compression heating effect is dependent on the domain size.

  9. Calculation of fusion gain in fast ignition with magnetic target by relativistic electrons and protons

    Directory of Open Access Journals (Sweden)

    A Parvazian

    2010-12-01

    Full Text Available Fast ignition is a new method for inertial confinement fusion (ICF in which the compression and ignition steps are separated. In the first stage, fuel is compressed by laser or ion beams. In the second phase, relativistic electrons are generated by pettawat laser in the fuel. Also, in the second phase 5-35 MeV protons can be generated in the fuel. Electrons or protons can penetrate in to the ultra-dense fuel and deposit their energy in the fuel . More recently, cylindrical rather than spherical fuel chambers with magnetic control in the plasma domain have been also considered. This is called magnetized target fusion (MTF. Magnetic field has effects on relativistic electrons energy deposition rate in fuel. In this work, fast ignition method in cylindrical fuel chambers is investigated and transportation of the relativistic electrons and protons is calculated using MCNPX and FLUKA codes with 0. 25 and 0. 5 tesla magnetic field in single and dual hot spot. Furthermore, the transfer rate of relativistic electrons and high energy protons to the fuel and fusion gain are calculated. The results show that the presence of external magnetic field guarantees higher fusion gain, and relativistic electrons are much more appropriate objects for ignition. MTF in dual hot spot can be considered as an appropriate substitution for the current ICF techniques.

  10. 1 d calculations on transport, neutral injection heating and ignition control in ZEPHYR

    International Nuclear Information System (INIS)

    1 - d transport calculations and particle trajectory calculations for neutral injection in Zephyr show that without impurity radiation losses a heating power of 20 MW and a pulse length of 1 s should be sufficient to reach ignition in Zephyr (average densities in the compressed stage between 2 and 4.5 x 1014 cm-3). The injection system should have an acceleration voltage of 160 keV; lower energy neutrals require higher heating powers. Heating of the plasma in the compressed stage requires neutral particle energies of > approx. 250 keV. Active burn control of the nearly ignited plasma is possible with heating powers of about 1 MW and response times of the feedback system smaller than 200 ms. (orig.) 891 HT/orig. 892 HIS

  11. Shock timing on the National Ignition Facility: The first precision tuning series

    Directory of Open Access Journals (Sweden)

    Robey H.F.

    2013-11-01

    Full Text Available Ignition implosions on the National Ignition Facility (NIF [Lindl et al., Phys. Plasmas 11, 339 (2004] are driven with a very carefully tailored sequence of four shock waves that must be timed to very high precision in order to keep the fuel on a low adiabat. The first series of precision tuning experiments on NIF have been performed. These experiments use optical diagnostics to directly measure the strength and timing of all four shocks inside the hohlraum-driven, cryogenic deuterium-filled capsule interior. The results of these experiments are presented demonstrating a significant decrease in the fuel adiabat over previously un-tuned implosions. The impact of the improved adiabat on fuel compression is confirmed in related deuterium-tritium (DT layered capsule implosions by measurement of fuel areal density (ρR, which show the highest fuel compression (ρR ∼ 1.0 g/cm2 measured to date.

  12. Shock timing on the National Ignition Facility: The first precision tuning series

    International Nuclear Information System (INIS)

    Ignition implosions on the National Ignition Facility (NIF) [Lindl et al., Phys. Plasmas 11, 339 (2004)] are driven with a very carefully tailored sequence of four shock waves that must be timed to very high precision in order to keep the fuel on a low adiabat. The first series of precision tuning experiments on NIF have been performed. These experiments use optical diagnostics to directly measure the strength and timing of all four shocks inside the hohlraum-driven, cryogenic deuterium-filled capsule interior. The results of these experiments are presented demonstrating a significant decrease in the fuel adiabat over previously un-tuned implosions. The impact of the improved adiabat on fuel compression is confirmed in related deuterium-tritium (DT) layered capsule implosions by measurement of fuel areal density (ρR), which show the highest fuel compression (ρR ∼1.0 g/cm2) measured to date. (authors)

  13. n-Butane: Ignition delay measurements at high pressure and detailed chemical kinetic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Healy, D.; Curran, H.J. [Combustion Chemistry Centre, School of Chemistry, NUI Galway (Ireland); Donato, N.S.; Aul, C.J.; Petersen, E.L. [Department of Mechanical Engineering, Texas A and M University, College Station, TX (United States); Zinner, C.M. [Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL (United States); Bourque, G. [Rolls-Royce Canada Limited, 9500 Cote de Liesse, Lachine, Quebec, H8T 1A2 (Canada)

    2010-08-15

    Ignition delay time measurements were recorded at equivalence ratios of 0.3, 0.5, 1, and 2 for n-butane at pressures of approximately 1, 10, 20, 30 and 45 atm at temperatures from 690 to 1430 K in both a rapid compression machine and in a shock tube. A detailed chemical kinetic model consisting of 1328 reactions involving 230 species was constructed and used to validate the delay times. Moreover, this mechanism has been used to simulate previously published ignition delay times at atmospheric and higher pressure. Arrhenius-type ignition delay correlations were developed for temperatures greater than 1025 K which relate ignition delay time to temperature and concentration of the mixture. Furthermore, a detailed sensitivity analysis and a reaction pathway analysis were performed to give further insight to the chemistry at various conditions. When compared to existing data from the literature, the model performs quite well, and in several instances the conditions of earlier experiments were duplicated in the laboratory with overall good agreement. To the authors' knowledge, the present paper presents the most comprehensive set of ignition delay time experiments and kinetic model validation for n-butane oxidation in air. (author)

  14. First downscattered neutron images from Inertial Confinement Fusion experiments at the National Ignition Facility

    OpenAIRE

    Guler Nevzat; Aragonez Robert J.; Archuleta Thomas N.; Batha Steven H.; Clark David D.; Clark Deborah J.; Danly Chris R.; Day Robert D.; Fatherley Valerie E.; Finch Joshua P.; Gallegos Robert A.; Garcia Felix P.; Grim Gary; Hsu Albert H.; Jaramillo Steven A.

    2013-01-01

    Inertial Confinement Fusion experiments at the National Ignition Facility (NIF) are designed to understand and test the basic principles of self-sustaining fusion reactions by laser driven compression of deuterium-tritium (DT) filled cryogenic plastic (CH) capsules. The experimental campaign is ongoing to tune the implosions and characterize the burning plasma conditions. Nuclear diagnostics play an important role in measuring the characteristics of these burning plasmas, providing feedback t...

  15. Longitudinal bunch compression study with induction voltage modulator

    Directory of Open Access Journals (Sweden)

    Nakayama Akira

    2013-11-01

    Full Text Available For the beam driver of inertial confinement fusion, the technology to compress a charged particle beam in longitudinal direction is crucially important. However, the quality of the beam is expected to be deteriorated when the beam is rapidly compressed in longitudinal direction. In order to investigate the beam dynamics during bunch compression, we made a compact beam compression system and carried out beam compression experiments. In this paper, we show the background of our study and recent progress of the beam compression experiments.

  16. Development of a High Power Programmable Precise Time-Delay Trigger/Ignition System for MFCG

    Institute of Scientific and Technical Information of China (English)

    WU Bi; HE Yuan-hang; ZHANG Qing-ming; MA Yue-fen

    2008-01-01

    High-power precise delay trigger/ignition system is a programmable pulse generator developed for experiment controlling in explosively driven magnetic flux compression generators.Precise delay pulses are generated by the digital circuit,after being magnified and sharpened through multistage isolated amplifiers and rising edge sharpening device,high-voltage steep delay pulses with precision less than us level are obtained.This system has been used in our compact magnetic flux compression generator experiments in place of the traditional primaeord delay device.

  17. Relativistic self focussing of laser beams at fast ignitor inertial fusion with volume ignition

    International Nuclear Information System (INIS)

    The alternative to the magnetic confinement fusion is inertial fusion energy mostly using lasers as drivers for compression and heating of pellets with deuterium and tritium fuel. Following the present technology of lasers with pulses of some megajoules energy and nanosecond duration, a power station for very low cost energy production (and without the problems of well erosion of magnetic confinement) could be available within 15 to 20 years. For the pellet compression, the scheme of spark ignition was mostly applied but its numerous problems with asymmetries and instabilities may be overcome by the alternative scheme of high gain volume ignition. This is a well established option of inertial fusion energy with lasers where a large range of possible later improvements is implied with respect to laser technology or higher plasma compression leading to energy production of perhaps five times below the present lowest level cost from fission reactors. A further improvement may be possible by the recent development of lasers with picosecond pulse duration using the fast igniter scheme which may reach even higher fusion gains with laser pulse energies of some 100 kilojoules

  18. Physics of compact ignition tokamak designs

    International Nuclear Information System (INIS)

    Models for predicting plasma performance in compact ignition experiments are constructed on the basis of theoretical and empirical constraints and data from tokamak experiments. Emphasis is placed on finding transport and confinement models which reproduce results of both ohmically and auxiliary heated tokamak data. Illustrations of the application of the models to compact ignition designs are given

  19. National Ignition Facility for Inertial Confinement Fusion

    International Nuclear Information System (INIS)

    The National Ignition Facility for inertial confinement fusion will contain a 1.8 MJ, 500 TW frequency-tripled neodymium glass laser system that will be used to explore fusion ignition and other problems in the physics of high temperature and density. We describe the facility briefly. The NIF is scheduled to be completed in 2003

  20. Advanced ignition and propulsion technology program

    Energy Technology Data Exchange (ETDEWEB)

    Oldenborg, R.; Early, J.; Lester, C.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Reliable engine re-ignition plays a crucial role in enabling commercial and military aircraft to fly safely at high altitudes. This project addressed research elements critical to the optimization of laser-based igniter. The effort initially involved a collaborative research and development agreement with B.F. Goodrich Aerospace and Laser Fare, Inc. The work involved integrated experiments with theoretical modeling to provide a basic understanding of the chemistry and physics controlling the laser-induced ignition of fuel aerosols produced by turbojet engine injectors. In addition, the authors defined advanced laser igniter configurations that minimize laser packaging size, weight, complexity and power consumption. These innovative ignition concepts were shown to reliably ignite jet fuel aerosols over a broad range of fuel/air mixture and a t fuel temperatures as low as -40 deg F. The demonstrated fuel ignition performance was highly superior to that obtained by the state-of-the-art, laser-spark ignition method utilizing comparable laser energy. The authors also developed a laser-based method that effectively removes optically opaque deposits of fuel hydrocarbon combustion residues from laser window surfaces. Seven patents have been either issued or are pending that resulted from the technology developments within this project.

  1. Modelling piloted ignition of wood and plastics

    NARCIS (Netherlands)

    Blijderveen, M. van; Bramer, E.A.; Brem, G.

    2012-01-01

    To gain insight in the startup of an incinerator, this article deals with piloted ignition. A newly developed model is described to predict the piloted ignition times of wood, PMMA and PVC. The model is based on the lower flammability limit and the adiabatic flame temperature at this limit. The inco

  2. Isochoric Implosions for Fast Ignition

    International Nuclear Information System (INIS)

    Various gain models have shown the potentially great advantages of Fast Ignition (FI) Inertial Confinement Fusion (ICF) over its conventional hot spot ignition counterpart [e.g., S. Atzeni, Phys. Plasmas 6, 3316 (1999); M. Tabak et al., Fusion Sci. and Technology 49, 254 (2006)]. These gain models, however, all assume nearly uniform-density fuel assemblies. In contrast, conventional ICF implosions yield hollowed fuel assemblies with a high-density shell of fuel surrounding a low-density, high-pressure hot spot. Hence, to realize fully the advantages of FI, an alternative implosion design must be found which yields nearly isochoric fuel assemblies without substantial hot spots. Here, it is shown that a self-similar spherical implosion of the type originally studied by Guderley [Luftfahrtforschung 19, 302 (1942)] may be employed to yield precisely such quasi-isochoric imploded states. The difficulty remains, however, of accessing these self-similarly imploding configurations from initial conditions representing an actual ICF target, namely a uniform, solid-density shell at rest. Furthermore, these specialized implosions must be realized for practicable drive parameters and at the scales and energies of interest in ICF. A direct-drive implosion scheme is presented which meets all of these requirements and reaches a nearly isochoric assembled density of 300 g=cm3 and areal density of 2.4 g=cm2 using 485 kJ of laser energy

  3. A reduced mechanism for predicting the ignition timing of a fuel blend of natural-gas and n-heptane in HCCI engine

    International Nuclear Information System (INIS)

    Highlights: • A two-stage reduction process is used to produce two reduced mechanisms. • The mechanisms are combined to develop a reaction mechanism for a fuel blend. • The genetic algorithm is used for optimization of reaction constants. • The developed reduced mechanism can be used to predict the ignition timing in HCCI engine for a fuel blend. - Abstract: One of the main challenges associated with homogeneous charge compression ignition (HCCI) combustion engine application is the lack of direct control on ignition timing. One of the solutions to this problem is mixing two fuels with various properties at a variety of ratios on a cycle-by-cycle basis. In the current study, a reduced mechanism for a fuel blend of natural-gas and n-heptane is proposed. The approach is validated for the prediction of ignition timing in the HCCI combustion engine. A single-zone combustion model is used to simulate the HCCI engine. A two-stage reduction process is used to produce two reduced mechanisms of existing semi-detailed GRI-Mech. 3.0 mechanism that contains 53 species and 325 reactions and Golovichev’s mechanism consisting of 57 species and 290 reactions for natural gas and n-heptane fuels, respectively. Firstly, the unimportant species and related reactions are identified by employing the directed relation graph with error propagation (DRGEP) reduction method and then, to extend reduction, the principal component analysis (PCA) method is utilized. To evaluate the validity of the reduced mechanism, representative engine combustion parameters such as peak pressure, maximum heat release, and CA50 are used. The reduced mechanism of GRI-Mech. 3.0 mechanism, containing 19 species and 39 reactions, and the reduced mechanism of Golovichev’s mechanism, consisting of 40 species and 95 reactions, provide good prediction for the mentioned parameters in comparison with those of detailed mechanisms. The combination of the generated reduced mechanisms is used to develop a

  4. The HiPER project for inertial confinement fusion and some experimental results on advanced ignition schemes

    International Nuclear Information System (INIS)

    This paper presents the goals and some of the results of experiments conducted within the Working Package 10 (Fusion Experimental Programme) of the HiPER Project. These experiments concern the study of the physics connected to 'advanced ignition schemes', i.e. the fast ignition and the shock ignition approaches to inertial fusion. Such schemes are aimed at achieving a higher gain, as compared with the classical approach which is used in NIF, as required for future reactors, and make fusion possible with smaller facilities. In particular, a series of experiments related to fast ignition were performed at the RAL (UK) and LULI (France) Laboratories and studied the propagation of fast electrons (created by a short-pulse ultra-high-intensity beam) in compressed matter, created either by cylindrical implosions or by compression of planar targets by (planar) laser-driven shock waves. A more recent experiment was performed at PALS and investigated the laser–plasma coupling in the 1016 W cm−2 intensity regime of interest for shock ignition.

  5. The HiPER project for inertial confinement fusion and some experimental results on advanced ignition schemes

    Science.gov (United States)

    Batani, D.; Koenig, M.; Baton, S.; Perez, F.; Gizzi, L. A.; Koester, P.; Labate, L.; Honrubia, J.; Antonelli, L.; Morace, A.; Volpe, L.; Santos, J.; Schurtz, G.; Hulin, S.; Ribeyre, X.; Fourment, C.; Nicolai, P.; Vauzour, B.; Gremillet, L.; Nazarov, W.; Pasley, J.; Richetta, M.; Lancaster, K.; Spindloe, Ch; Tolley, M.; Neely, D.; Kozlová, M.; Nejdl, J.; Rus, B.; Wolowski, J.; Badziak, J.; Dorchies, F.

    2011-12-01

    This paper presents the goals and some of the results of experiments conducted within the Working Package 10 (Fusion Experimental Programme) of the HiPER Project. These experiments concern the study of the physics connected to 'advanced ignition schemes', i.e. the fast ignition and the shock ignition approaches to inertial fusion. Such schemes are aimed at achieving a higher gain, as compared with the classical approach which is used in NIF, as required for future reactors, and make fusion possible with smaller facilities. In particular, a series of experiments related to fast ignition were performed at the RAL (UK) and LULI (France) Laboratories and studied the propagation of fast electrons (created by a short-pulse ultra-high-intensity beam) in compressed matter, created either by cylindrical implosions or by compression of planar targets by (planar) laser-driven shock waves. A more recent experiment was performed at PALS and investigated the laser-plasma coupling in the 1016 W cm-2 intensity regime of interest for shock ignition.

  6. Fractal image compression

    OpenAIRE

    Žemlo, Gražina

    2004-01-01

    One of the images compression methods – fractal image compression is analyzed in the work. After work carried out, it is possible to state, that selecting parameters of method of fractal compression depends on user’s demands.

  7. Compression limits in cascaded quadratic soliton compression

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2008-01-01

    Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency.......Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency....

  8. FIREBALL: Fusion Ignition Rocket Engine with Ballistic Ablative Lithium Liner

    International Nuclear Information System (INIS)

    Thermo-nuclear fusion may be the key to a high Isp, high specific power propulsion system. In a fusion system energy is liberated within, and imparted directly to, the propellant. In principle, this can overcome the performance limitations inherent in systems that require thermal power transfer across a material boundary, and/or multiple power conversion stages (NTR, NEP). A thermo-nuclear propulsion system, which attempts to overcome some of the problems inherent in the Orion concept, is described. A dense FRC plasmoid is accelerated to high velocity (in excess of 500 km/s) and is compressed into a detached liner (pulse unit). The kinetic energy of the FRC is converted into thermal and magnetic-field energy, igniting a fusion burn in the magnetically confined plasma. The fusion reaction serves as an ignition source for the liner, which is made out of detonable materials. The energy liberated in this process is converted to thrust by a pusher-plate, as in the classic Orion concept. However with this concept, the vehicle does not carry a magazine of autonomous pulse-units. By accelerating a second, heavier FRC, which acts as a piston, right behind the first one, the velocity required to initiate the fusion burn is greatly reduced

  9. Glass laser system, Gekko XII upgrade for ICF ignition

    International Nuclear Information System (INIS)

    Recent progresses have shown the possibility of the ignition at the inertial confinement fusion experiment in the direct drive scheme. The imploded core of burning temperature, 5-10 keV, and the imploded core of 600 times liquid fuel density have been realized separately at Osaka University by using less than 10 kJ energy with 3% energy balance. While the high temperature core could only generate the neutrons up to a level of one tenth to a hundredth predicted by the one dimensional calculation at a compression ratio over ten. The required energy and its uniformity on the spherical pellet are trade-off for given the resultant of the implosion. The key issue in the inertial fusion energy development is now the realization of the ignition which is one of milestones to the energy production by the ICF. In this report, the basic design of the Gekko XII upgrade system named open-quotes Kongohclose quotes at Osaka University is discussed with system components being developed now to improve the uniformity, controllability, and the energy delivering in the existing building of Gekko XII

  10. The Neutron Imaging System Fielded at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Merrill, F E; Buckles, R; Clark, D D; Danly, C R; Drury, O B; Dzenitis, J M; Fatherley, V E; Fittinghoff, D N; Gallegos, R; Grim, G P; Guler, N; Loomis, E N; Lutz, S; Malone, R M; Martinson, D D; Mares, D; Morley, D J; Morgan, G L; Oertel, J A; Tregillis, I L; Volegov, P L; Weiss, P B; Wilde, C H

    2012-08-01

    A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important diagnostic tool for inertial fusion studies at the NIF for measuring the size and shape of the burning DT plasma during the ignition stage of Inertial Confinement Fusion (ICF) implosions. The imaging technique utilizes a pinhole neutron aperture, placed between the neutron source and a neutron detector. The detection system measures the two dimensional distribution of neutrons passing through the pinhole. This diagnostic has been designed to collect two images at two times. The long flight path for this diagnostic, 28 m, results in a chromatic separation of the neutrons, allowing the independently timed images to measure the source distribution for two neutron energies. Typically the first image measures the distribution of the 14 MeV neutrons and the second image of the 6-12 MeV neutrons. The combination of these two images has provided data on the size and shape of the burning plasma within the compressed capsule, as well as a measure of the quantity and spatial distribution of the cold fuel surrounding this core.

  11. A new and efficient mechanism for spark ignition engines

    International Nuclear Information System (INIS)

    Highlights: • A new slider–crank mechanism, with superior performance is presented. • Thermodynamic processes as well as vibration and internal forces have been modeled. • Comparison with the conventional four-stroke spark ignition engines is made. • Advantages and disadvantages of the proposed mechanism are discussed. - Abstract: In this paper a new symmetrical crank and slider mechanism is proposed and a zero dimensional model is utilized to study its combustion performance enhancement in a four-stroke spark ignition (SI) engine. The main features of this new mechanism are superior thermodynamic efficiency, lower internal frictions, and lower pollutants. Comparison is made between its performance and that of the conventional four-stroke SI engines. Presented mechanism is designed to provide better fuel consumption of internal combustion engines. These advantages over standard engine are achieved through synthesis of new mechanism. Numerical calculation have been performed for several cases of different mechanism parameters, compression ratio and engine speed. A comprehensive comparison between their thermodynamic processes as well as vibration and internal forces has been done. Calculated efficiency and power diagrams are plotted and compared with performance of a conventional SI engine. Advantages and disadvantages of the proposed mechanism are discussed in details

  12. Satellite data compression

    CERN Document Server

    Huang, Bormin

    2011-01-01

    Satellite Data Compression covers recent progress in compression techniques for multispectral, hyperspectral and ultra spectral data. A survey of recent advances in the fields of satellite communications, remote sensing and geographical information systems is included. Satellite Data Compression, contributed by leaders in this field, is the first book available on satellite data compression. It covers onboard compression methodology and hardware developments in several space agencies. Case studies are presented on recent advances in satellite data compression techniques via various prediction-

  13. Lossy Image Compression

    CERN Document Server

    Shukla, KK

    2011-01-01

    Image compression is concerned with minimization of the number of information carrying units used to represent an image. Lossy compression techniques incur some loss of information which is usually imperceptible. In return for accepting this distortion, we obtain much higher compression ratios than is possible with lossless compression. Salient features of this book include: four new image compression algorithms and implementation of these algorithms; detailed discussion of fuzzy geometry measures and their application in image compression algorithms; new domain decomposition based algorithms

  14. Hydrodynamic growth and mix experiments at National Ignition Facility

    Science.gov (United States)

    Smalyuk, V. A.; Caggiano, J.; Casey, D.; Cerjan, C.; Clark, D. S.; Edwards, J.; Grim, G.; Haan, S. W.; Hammel, B. A.; Hamza, A.; Hsing, W.; Hurricane, O.; Kilkenny, J.; Kline, J.; Knauer, J.; Landen, O.; McNaney, J.; Mintz, M.; Nikroo, A.; Parham, T.; Park, H.-S.; Pino, J.; Raman, K.; Remington, B. A.; Robey, H. F.; Rowley, D.; Tipton, R.; Weber, S.; Yeamans, C.

    2016-03-01

    Hydrodynamic growth and its effects on implosion performance and mix were studied at the National Ignition Facility (NIF). Spherical shells with pre-imposed 2D modulations were used to measure Rayleigh-Taylor (RT) instability growth in the acceleration phase of implosions using in-flight x-ray radiography. In addition, implosion performance and mix have been studied at peak compression using plastic shells filled with tritium gas and imbedding localized CD diagnostic layer in various locations in the ablator. Neutron yield and ion temperature of the DT fusion reactions were used as a measure of shell-gas mix, while neutron yield of the TT fusion reaction was used as a measure of implosion performance. The results have indicated that the low-mode hydrodynamic instabilities due to surface roughness were the primary culprits to yield degradation, with atomic ablator-gas mix playing a secondary role.

  15. The Influence of Plasma Ignition on the Ignition Performance of High-energy Nitramine Gun Propellant%等离子体点火对高能硝胺发射药点火性能影响研究

    Institute of Scientific and Technical Information of China (English)

    刘强; 张玉成; 张江波; 刘毅; 闫光虎

    2014-01-01

    The ignition characteristics of high energy nitramine gun propellant under different plasma jet intensity were studied, and compared to that of the traditional ignition. Meanwhile, the static and dynamic ignition characteristics of nitramine gun propellant under different ways of ignition were analyzed, and the effect of adjusting the plasma energy upon ignition of gun propellant was discussed. The result shows that the delay time of plasma ignition is obviously shorter than that of traditional ignition. The ignition time will be shortened when the ignition energy of plasma is promoted, and the combustion time of gun propellant will be also shortened. In the closed vessel, the ignition and combustion time will be shortened with the charge density of gun propellant promoting. The gradient at initial period of p——t curve of plasma ignition is larger than that of traditional ignition,which indicates that the plasma ignition has obvious effect on the gun propellant combustion.%采用等离子体点火的方法研究了高能硝胺发射药在不同等离子体射流条件作用下的点火特性,与常规点火方式的点火特性进行了比较,分析了不同点火方式下高能硝胺发射药的静、动态点火效果,并探讨了调节等离子体点火能量对发射药点火性能影响。试验结果表明:与常规点火方式相比,等离子体点火延迟时间明显缩短;增加等离子体点火能量会使发射药点火时间短、燃烧速度快;密闭爆发器中,随着发射药装填密度增大,点火和燃烧时间均变短;受等离子体射流点火的影响,等离子体点火膛压曲线上升前期坡度比常规点火膛压曲线陡,对发射药点火燃烧影响更显著。

  16. National Ignition Facility site requirements

    International Nuclear Information System (INIS)

    The Site Requirements (SR) provide bases for identification of candidate host sites for the National Ignition Facility (NIF) and for the generation of data regarding potential actual locations for the facilities. The SR supplements the NIF Functional Requirements (FR) with information needed for preparation of responses to queries for input to HQ DOE site evaluation. The queries are to include both documents and explicit requirements for the potential host site responses. The Sr includes information extracted from the NIF FR (for convenience), data based on design approaches, and needs for physical and organization infrastructure for a fully operational NIF. The FR and SR describe requirements that may require new construction or may be met by use or modification of existing facilities. The SR do not establish requirements for NIF design or construction project planning. The SR document does not constitute an element of the NIF technical baseline

  17. Performance and Emission Characteristics on Glow Plug Hot Surface Ignition C.I. Engine Using Methanol as Fuel With Additive

    Directory of Open Access Journals (Sweden)

    B.OMPRAKASH

    2015-07-01

    Full Text Available The concept of using alcohol fuels as alternative to diesel fuel in diesel engine is recent one. The scarcity of transportation petroleum fuels due to the fast depletion of the petroleum deposits and frequent rise in their costs in the international market have spurred many efforts to find alternatives. Alcohols were quickly recognized as prime candidates to displace or replace high octane petroleum fuels. Innovative thinking led to find varies techniques by which alcohol can be used as fuel in diesel engine. Amongst the fuel alternative proposed, the most favourest ones are methanol and ethanol. The specific tendency of alcohols to ignite easily from a hot surface makes it suitable to ignite in a diesel engine by different methods. The advantage of this property of alcohols enables to design and construct a new type of engine called surface ignition engine. Methanol and ethanol are very susceptible to surface ignition, this method is very suitable for these fuels. The hot surfaces which, can be used in surface ignition engine are electrically heated glow plug with hot surface. Hence present research work carries the experimental investigation on glow plug hot surface ignition engine, by adding different additives with methanol and ethanol as fuels, with an objective to find the best one performance, emission and compression parameters.

  18. The National Ignition Facility project

    Energy Technology Data Exchange (ETDEWEB)

    Paisner, J.A.; Boyes, J.D.; Kumpan, S.A.; Sorem, M.

    1996-06-01

    The Secretary of the U.S. Department of Energy (DOE) commissioned a Conceptual Design Report (CDR) for the National Ignition Facility (NIF) in January 1993 as part of a Key Decision Zero (KD0), justification of Mission Need. Motivated by the progress to date by the Inertial Confinement Fusion (ICF) program in meeting the Nova Technical Contract goals established by the National Academy of Sciences in 1989, the Secretary requested a design using a solid-state laser driver operating at the third harmonic (0.35 {mu}m) of neodymium (Nd) glass. The participating ICF laboratories signed a Memorandum of Agreement in August 1993, and established a Project organization, including a technical team from the Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Sandia National Laboratories (SNL), and the Laboratory for Laser Energetics at the University of Rochester. Since then, the authors completed the NIF conceptual design, based on standard construction at a generic DOE Defense Program`s site, and issued a 7,000-page, 27-volume CDR in May 1994. Over the course of the conceptual design study, several other key documents were generated, including a Facilities Requirements Document, a Conceptual Design Scope and Plan, a Target Physics Design Document, a Laser Design Cost Basis Document, a Functional Requirements Document, an Experimental Plan for Indirect Drive Ignition, and a Preliminary Hazards Analysis (PHA) Document. DOE used the PHA to categorize the NIF as a low-hazard, non-nuclear facility. This article presents an overview of the NIF project.

  19. IMPROVEMENT TO PIPELINE COMPRESSOR ENGINE RELIABILITY THROUGH RETROFIT MICRO-PILOT IGNITION SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Scott Chase; Daniel Olsen; Ted Bestor

    2005-05-01

    This report documents a 3-year research program conducted by the Engines & Energy Conversion Laboratory (EECL) at Colorado State University (CSU) to develop micropilot ignition systems for existing pipeline compressor engines. Research activities for the overall program were conducted with the understanding that the efforts are to result in a commercial product to capture and disseminate the efficiency and environmental benefits of this new technology. An extensive state-of-art review was conducted to leverage the existing body of knowledge of micropilot ignition with respect to retrofit applications. Additionally, commercially-available fuel injection products were identified and applied to the program where appropriate. This approach will minimize the overall time-to-market requirements, while meeting performance and cost criteria. The objective for Phase I was to demonstrate the feasibility of micropilot ignition for large bore, slow speed engines operating at low compression ratios under laboratory conditions at the EECL. The primary elements of Micropilot Phase I were to develop a single-cylinder test chamber to study the injection of pilot fuel into a combustion cylinder and to develop, install and test a multi-cylinder micropilot ignition system for a 4-cylinder, natural gas test engine. In all, there were twelve (12) tasks defined and executed to support these two (2) primarily elements in a stepwise fashion. Task-specific approaches and results are documented in this report. The four-cylinder prototype data was encouraging for the micro-pilot ignition technology when compared to spark ignition. The objective for Phase II was to further develop and optimize the micropilot ignition system at the EECL for large bore, slow speed engines operating at low compression ratios. The primary elements of Micropilot Phase II were to evaluate the results for the 4-cylinder system prototype developed for Phase I, then optimize this system and prepare the technology for

  20. Effect of glycerol ethoxylate as an ignition improver on injection and combustion characteristics of hydrous ethanol under CI engine condition

    International Nuclear Information System (INIS)

    Highlights: • Glycerol ethoxylate (GE) shows the similar results as the commercial additive. • GE decreases injection rate, but increases injection delay and duration of ethanol. • GE shortens ignition delay and decreases heat released in premixed burn of ethanol. • GE has a minor effect on flame temperature of ethanol. • KL factor and soot of ethanol are sensitive to both GE and the commercial additive. - Abstract: This paper investigates the effects of glycerol ethoxylate as an ignition improver on injection and combustion characteristics of hydrous ethanol under a CI engine condition. Injection characteristics were investigated by an in-house injection rate measurement device based on the Zeuch method, while spray combustion has been performed in the rapid compression and expansion machine (RCEM). The CI engine condition indicated as density, pressure and temperature of compressed synthetic gas, consisting of 80% argon and 20% oxygen, at fuel injection timing in RCEM of 21 kg/m3, 4.4 MPa and 900 K, respectively. This condition is equivalent to the isentropic compression of air of the actual CI engine with compression ratio of 22. Hydrous ethanol without ignition improver (Eh95) and the ethanol dedicated for heavy duty vehicles (ED95: composed of hydrous ethanol with the commercial additive for ED95) are reference fuels representing low and high quality ethanol fuel for CI engines, respectively. All test fuels are injected at constant heat input. The results indicate that the additional ignition improvers change injection characteristics, i.e. injection delay, injection rate and discharge coefficient of hydrous ethanol. The maximum injection rates at fully opened needle for the ethanol dedicated for heavy duty vehicles (ED95) and hydrous ethanol with 5% glycerol ethoxylate (5%GE) are lower than that of hydrous ethanol without ignition improver (Eh95) by approximately 10%. Additional injection duration is required for ED95 and 5%GE to maintain a constant

  1. 30 CFR 35.20 - Autogenous-ignition temperature test.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Autogenous-ignition temperature test. 35.20... Autogenous-ignition temperature test. (a) Purpose. The purpose of this test, referred to hereinafter as the ignition-temperature test, is to determine the lowest autogenous-ignition temperature of a hydraulic...

  2. Approach to ignition of tokamak reactors

    International Nuclear Information System (INIS)

    Recent transport modeling results for JET, INTOR, and ETF are reviewed and analyzed with respect to existing uncertainties in the underlying physics, the self-consistency of the very large numerical codes, and the margin for ignition. The codes show ignition to occur in ETF/INTOR-sized machines if empirical scaling can be extrapolated to ion temperatures (and beta values) much higher than those presently achieved, if there is no significant impurity accumulation over the first 7 s, and if the known ideal and resistive MHD instabilities remain controllable for the evolving plasma profiles during ignition startup

  3. Incremental Pressing Technique in Explosive Charge

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A pressing technique has become available that might be useful for compressing granular explosives. If the height-diameter ratio of the charge is unfavorable,the high quality charge can not be obtained with the common single-action pressing. This paper presents incremental pressing technique, which can obtain the charge with higher overall density and more uniform density.

  4. Prospects of lean ignition with the quarter wave coaxial cavity igniter

    Science.gov (United States)

    Pertl, Franz Andreas Johannes

    New ignition sources are needed to operate the next generation of lean high efficiency internal combustion engines. A significant environmental and economic benefit could be obtained from these lean engines. Toward this goal, the quarter wave coaxial cavity resonator, QWCCR, igniter was examined. A detailed theoretical analysis of the resonator was performed relating geometric and material parameters to performance characteristics, such as resonator quality factor and developed tip electric field. The analysis provided for the construction and evaluation of a resonator for ignition testing. The evaluation consisted of ignition tests with liquefied-petroleum-gas (LPG) air mixtures of varying composition. The combustion of these mixtures was contained in a closed steel vessel with a precombustion pressure near one atmosphere. The resonator igniter was fired in this vessel with a nominal 150 W microwave pulse of varying duration, to determine ignition energy limits for various mixtures. The mixture compositions were determined by partial pressure measurement and the ideal gas law. Successful ignition was determined through observation of the combustion through a view port. The pulse and reflected microwave power were captured in real time with a high-speed digital storage oscilloscope. Ignition energies and power levels were calculated from these measurements. As a comparison, these ignition experiments were also carried out with a standard non-resistive spark plug, where gap voltage and current were captured for energy calculations. The results show that easily ignitable mixtures around stoichiometric and slightly rich compositions are ignitable with the QWCCR using the similar kinds of energies as the conventional spark plug in the low milli-Joule range. Energies for very lean mixtures could not be determined reliably for the QWCCR for this prototype test, but could be lower than that for a conventional spark. Given the capability of high power, high energy delivery

  5. Hypervelocity Impact Fusion with Compressed Deuterium-Tritium Targets

    OpenAIRE

    Olariu, Silviu

    1998-01-01

    The neutron yields observed in inertial confinement fusion experiments for higher convergence ratios are about two orders of magnitude smaller than the neutron yields predicted by one-dimensional models, the discrepancy being attributed to the development of instabilities. We consider the possibility that ignition and a moderate gain could be achieved with existing laser facilities if the laser driver energy is used to produce only the radial compression of the fuel capsule to high densities ...

  6. Fast ignition of an inertial fusion target with a solid noncryogenic fuel by an ion beam

    Science.gov (United States)

    Gus'kov, S. Yu.; Zmitrenko, N. V.; Il'in, D. V.; Sherman, V. E.

    2015-09-01

    The burning efficiency of a preliminarily compressed inertial confinement fusion (ICF) target with a solid noncryogenic fuel (deuterium-tritium beryllium hydride) upon fast central ignition by a fast ion beam is studied. The main aim of the study was to determine the extent to which the spatial temperature distribution formed under the heating of an ICF target by ion beams with different particle energy spectra affects the thermonuclear gain. The study is based on a complex numerical modeling including computer simulations of (i) the heating of a compressed target with a spatially nonuniform density and temperature distributions by a fast ion beam and (ii) the burning of the target with the initial spatial density distribution formed at the instant of maximum compression of the target and the initial spatial temperature distribution formed as a result of heating of the compressed target by the ion beam. The threshold energy of the igniting ion beam and the dependence of the thermonuclear gain on the energy deposited in the target are determined.

  7. Fast ignition of an inertial fusion target with a solid noncryogenic fuel by an ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Gus’kov, S. Yu., E-mail: guskov@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Zmitrenko, N. V. [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Il’in, D. V.; Sherman, V. E. [St. Petersburg State Polytechnic University (Russian Federation)

    2015-09-15

    The burning efficiency of a preliminarily compressed inertial confinement fusion (ICF) target with a solid noncryogenic fuel (deuterium-tritium beryllium hydride) upon fast central ignition by a fast ion beam is studied. The main aim of the study was to determine the extent to which the spatial temperature distribution formed under the heating of an ICF target by ion beams with different particle energy spectra affects the thermonuclear gain. The study is based on a complex numerical modeling including computer simulations of (i) the heating of a compressed target with a spatially nonuniform density and temperature distributions by a fast ion beam and (ii) the burning of the target with the initial spatial density distribution formed at the instant of maximum compression of the target and the initial spatial temperature distribution formed as a result of heating of the compressed target by the ion beam. The threshold energy of the igniting ion beam and the dependence of the thermonuclear gain on the energy deposited in the target are determined.

  8. Fast ignition of an inertial fusion target with a solid noncryogenic fuel by an ion beam

    International Nuclear Information System (INIS)

    The burning efficiency of a preliminarily compressed inertial confinement fusion (ICF) target with a solid noncryogenic fuel (deuterium-tritium beryllium hydride) upon fast central ignition by a fast ion beam is studied. The main aim of the study was to determine the extent to which the spatial temperature distribution formed under the heating of an ICF target by ion beams with different particle energy spectra affects the thermonuclear gain. The study is based on a complex numerical modeling including computer simulations of (i) the heating of a compressed target with a spatially nonuniform density and temperature distributions by a fast ion beam and (ii) the burning of the target with the initial spatial density distribution formed at the instant of maximum compression of the target and the initial spatial temperature distribution formed as a result of heating of the compressed target by the ion beam. The threshold energy of the igniting ion beam and the dependence of the thermonuclear gain on the energy deposited in the target are determined

  9. Thermal Expansion and Compressibility in Superconducting NaxCoO2o4xD2O (x?1/3): Evidence for Pressure-Induced Charge Redistribution

    OpenAIRE

    Jorgensen, J. D.; Avdeev, M.; Hinks, D. G.; Barnes, P. W.; Short, S.(Queen Mary University of London, School of Physics and Astronomy, London, United Kingdom)

    2005-01-01

    We have performed thermal expansion and compressibility measurements on the recently discovered superconducting material NaxCoO2*4xD2O (x=1/3) using neutron powder diffraction over the temperature range 10-295 K and the pressure range 0-0.6 GPa. Pressure measurements were done in a helium-gas pressure cell. Both the thermal expansion and compressibility are very anisotropic, with the largest effects along the c axis, as would be expected for a layered material with weak hydrogen bonding nomin...

  10. Ignition properties of nuclear grade activated carbons

    International Nuclear Information System (INIS)

    The ignition property of new activated carbons used in air cleaning systems of nuclear facilities has been evaluated in the past, however very little information has been generated on the behavior of aged, weathered carbons which have been exposed to normal nuclear facility environment. Additionally the standard procedure for evaluation of ignition temperature of carbon is performed under very different conditions than those used in the design of nuclear air cleaning systems. Data were generated evaluating the ageing of activated carbons and comparing their CH3131I removal histories to their ignition temperatures. A series of tests were performed on samples from one nuclear power reactor versus use time, a second series evaluated samples from several plants showing the variability of atmospheric effects. The ignition temperatures were evaluated simulating the conditions existing in nuclear air cleaning systems, such as velocity, bed depth, etc., to eliminate potential confusion resulting from artifically set current standard conditions

  11. Fast ignition by quasimonoenergetic ion beams

    Directory of Open Access Journals (Sweden)

    Honrubia J.J.

    2013-11-01

    Full Text Available The potential of quasimonoenergetic ion beams for fast ignition (FI of fusion targets is investigated. Lithium, carbon, aluminium and vanadium ions have been considered here to determine the optimal kinetic energy for each ion type. Our calculations show that the ignition energies of those beams impinging on a standard fuel configuration are similar. However, they are obtained for very different ion energies. Assuming that the ions can be focused onto 10 μm spots, a new irradiation scheme that reduces substantially the ignition energies is proposed. The combination of using intermediate ions, such as 5.5 GeV vanadium, and the new irradiation scheme allows one to reduce the number of ions required for ignition by roughly three orders of magnitude when compared with the standard proton FI scheme.

  12. Plasma igniter for internal-combustion engines

    Science.gov (United States)

    Breshears, R. R.; Fitzgerald, D. J.

    1978-01-01

    Hot ionized gas (plasma) ignites air/fuel mixture in internal combustion engines more effectively than spark. Electromagnetic forces propel plasma into combustion zone. Combustion rate is not limited by flame-front speed.

  13. Stabilization of high-compression, indirect-drive inertial confinement fusion implosions using a 4-shock adiabat-shaped drive

    International Nuclear Information System (INIS)

    Hydrodynamic instabilities and poor fuel compression are major factors for capsule performance degradation in ignition experiments on the National Ignition Facility. Using a recently developed laser drive profile with a decaying first shock to tune the ablative Richtmyer-Meshkov (ARM) instability and subsequent in-flight Rayleigh-Taylor growth, we have demonstrated reduced growth compared to the standard ignition pulse whilst maintaining conditions for a low fuel adiabat needed for increased compression. Using in-flight x-ray radiography of pre-machined modulations, the first growth measurements using this new ARM-tuned drive have demonstrated instability growth reduction of ∼4× compared to the original design at a convergence ratio of ∼2. Corresponding simulations give a fuel adiabat of ∼1.6, similar to the original goal and consistent with ignition requirements

  14. Stabilization of high-compression, indirect-drive inertial confinement fusion implosions using a 4-shock adiabat-shaped drive

    Energy Technology Data Exchange (ETDEWEB)

    MacPhee, A. G.; Peterson, J. L.; Casey, D. T.; Clark, D. S.; Haan, S. W.; Jones, O. S.; Landen, O. L.; Milovich, J. L.; Robey, H. F.; Smalyuk, V. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2015-08-15

    Hydrodynamic instabilities and poor fuel compression are major factors for capsule performance degradation in ignition experiments on the National Ignition Facility. Using a recently developed laser drive profile with a decaying first shock to tune the ablative Richtmyer-Meshkov (ARM) instability and subsequent in-flight Rayleigh-Taylor growth, we have demonstrated reduced growth compared to the standard ignition pulse whilst maintaining conditions for a low fuel adiabat needed for increased compression. Using in-flight x-ray radiography of pre-machined modulations, the first growth measurements using this new ARM-tuned drive have demonstrated instability growth reduction of ∼4× compared to the original design at a convergence ratio of ∼2. Corresponding simulations give a fuel adiabat of ∼1.6, similar to the original goal and consistent with ignition requirements.

  15. Stabilization of high-compression, indirect-drive inertial confinement fusion implosions using a 4-shock adiabat-shaped drive

    Science.gov (United States)

    MacPhee, A. G.; Peterson, J. L.; Casey, D. T.; Clark, D. S.; Haan, S. W.; Jones, O. S.; Landen, O. L.; Milovich, J. L.; Robey, H. F.; Smalyuk, V. A.

    2015-08-01

    Hydrodynamic instabilities and poor fuel compression are major factors for capsule performance degradation in ignition experiments on the National Ignition Facility. Using a recently developed laser drive profile with a decaying first shock to tune the ablative Richtmyer-Meshkov (ARM) instability and subsequent in-flight Rayleigh-Taylor growth, we have demonstrated reduced growth compared to the standard ignition pulse whilst maintaining conditions for a low fuel adiabat needed for increased compression. Using in-flight x-ray radiography of pre-machined modulations, the first growth measurements using this new ARM-tuned drive have demonstrated instability growth reduction of ˜4× compared to the original design at a convergence ratio of ˜2. Corresponding simulations give a fuel adiabat of ˜1.6, similar to the original goal and consistent with ignition requirements.

  16. Confinement scaling and ignition in tokamaks

    International Nuclear Information System (INIS)

    A drift wave turbulence model is used to compute the scaling and magnitude of central electron temperature and confinement time of tokamak plasmas. The results are in accord with experiment. Application to ignition experiments shows that high density (1 to 2) . 1015 cm-3, high field, B/sub T/ > 10 T, but low temperature T approx. 6 keV constitute the optimum path to ignition

  17. Loss/gain on ignition test report

    International Nuclear Information System (INIS)

    Document provides the results of tests done on Product Cans from the HC-21C sludge stabilization process. Tests included running a simulated Thermogravimetric Analysis, TGA, on the processed material that have received Loss On Ignition (LOI) sample results that show a gain on ignition or a high LOI and reprocessing product cans with high LOIs. Also, boat material temperatures in the furnace were tracked during the testing

  18. Dynamic Regime of Ignition of Solid Propellant

    Directory of Open Access Journals (Sweden)

    Zolotorev Nikolay

    2016-01-01

    Full Text Available This article presents a dynamic regime of exposure of the radiant flux on the sample of gun-cotton. Obtained time the ignition of gun-cotton in the heating conditions of increasing heat flux in the range from 0.2 W/cm2 to 22 W/cm2. A comparison of the delay times of the ignition when heated variable and constant heat flux.

  19. Chaotic Combustion in Spark Ignition Engines

    OpenAIRE

    Wendeker, M.; Czarnigowski, J.; Litak, G.; Szabelski, K.

    2002-01-01

    We analyse the combustion process in a spark ignition engine using the experimental data of an internal pressure during the combustion process and show that the system can be driven to chaotic behaviour. Our conclusion is based on the observation of unperiodicity in the time series, suitable stroboscopic maps and a complex structure of a reconstructed strange attractor. This analysis can explain that in some circumstances the level of noise in spark ignition engines increases considerably due...

  20. Thermonuclear ignition in the next generation tokamaks

    International Nuclear Information System (INIS)

    The extrapolation of experimental rules describing energy confinement and magnetohydrodynamic - stability limits, in known tokamaks, allow to show that stable thermonuclear ignition equilibria should exist in this configuration, if the product aBtx of the dimensions by a magnetic-field power is large enough. Quantitative application of this result to several next-generation tokamak projects show that those kinds of equilibria could exist in such devices, which would also have enough additional heating power to promote an effective accessible ignition

  1. Ignition by Hot Transient Jets in Confined Mixtures of Gaseous Fuels and Air

    Directory of Open Access Journals (Sweden)

    Abdullah Karimi

    2016-01-01

    Full Text Available Ignition of a combustible mixture by a transient jet of hot reactive gas is important for safety of mines, prechamber ignition in IC engines, detonation initiation, and novel constant-volume combustors. The present work is a numerical study of the hot jet ignition process in a long constant-volume combustor (CVC that represents a wave rotor channel. The hot jet of combustion products from a prechamber is injected through a converging nozzle into the main CVC chamber containing a premixed fuel-air mixture. Combustion in a two-dimensional analogue of the CVC chamber is modeled using a global reaction mechanism, a skeletal mechanism, or a detailed reaction mechanism for three hydrocarbon fuels: methane, propane, and ethylene. Turbulence is modeled using the two-equation SST k-ω model, and each reaction rate is limited by the local turbulent mixing timescale. Hybrid turbulent-kinetic schemes using some skeletal reaction mechanisms and detailed mechanisms are good predictors of the experimental data. Shock wave traverse of the reaction zone is seen to significantly increase the overall reaction rate, likely due to compression heating, as well as baroclinic vorticity generation that stirs and mixes reactants and increases flame area. Less easily ignitable methane mixture is found to show slower initial reaction and greater dependence on shock interaction than propane and ethylene.

  2. Assessing target design robustness for Shock Ignition using 3D laser raytracing

    Science.gov (United States)

    Schiavi, Angelo; Atzeni, Stefano; Marocchino, Alberto

    2014-10-01

    Shock ignition (SI) is a laser direct-drive Inertial Confinement Fusion scheme in which fuel compression and hot spot formation are separated. Shock ignition shows potential for high gain at laser energy below 1 MJ (see review Ref.), and could be tested on present large scale facilities. We produced an analytical model for SI which allows rescaling of target and laser drive parameters starting from a given point design. The goal is to redefine a laser-target configuration increasing the robustness while preserving its performance. We developed a metric for ignition margins specific to SI. We report on simulations of rescaled targets using 2D hydrodynamic fluid model with 3D laser raytracing. The robustness with respect to target fabrication parameters and laser facility fluctuations will be assessed for an original reference design as well as for a rescaled target, testing the accuracy of the ignition margin predictor just developed. Work supported by the Italian MIUR Project PRIN2012AY5LEL.

  3. Shock induced ignition and DDT in the presence of mechanically driven fluctuations

    Science.gov (United States)

    Wang, Wentian; McDonald, James G.; Radulescu, Matei I.

    2015-11-01

    The present study addresses the problem of shock induced ignition and transition to detonation in the presence of mechanical and thermal fluctuations. These departures from a homogeneous medium are of significant importance in practical situations, where such fluctuations may promote hot-spot ignition and favor the flame transition to detonation. The problem is studied in 1D, where a piston-induced shock ignites the gas. The fluctuations in the shock-compressed medium are controlled by allowing the piston's speed to oscillate around a mean, with controllable frequency and amplitude. A Lagrangian numerical formulation is used, which allows to treat exactly the transient boundary condition at the piston head. The hydrodynamic solver is coupled with the reactive dynamics of the gas using Cantera. The code was verified by comparison with steady state ZND solutions and previous shock induced ignition results in homogeneous media. Results obtained for different fuels illustrate the strong relation of the DDT amplification length to mechanical fluctuations in systems with a high effective activation energy and fast rate of energy deposition, consistent with experiments performed on fast flame acceleration in the presence of strong mechanical perturbations. Financial support from NSERC and Shell, with A. Pekalski and M. Levin as technical monitors, are greatly acknowledged.

  4. Infrared thermographic study of laser ignition

    International Nuclear Information System (INIS)

    Pyrotechnic ignition has been studied in the past by making a limited number of discrete temperature-time observations during ignition. Present-day infrared scanning techniques make it possible to record thermal profiles, during ignition, with high spacial and temporal resolution. Data thus obtained can be used with existing theory to characterize pyrotechnic materials and to develop more precise kinetic models of the ignition process. Ignition has been studied theoretically and experimentally using various thermal methods. It has been shown that the whole process can, ideally, be divided into two stages. In the first stage, the sample pellet behaves like an inert body heated by an external heat source. The second stage is governed by the chemical reaction in the heated volume produced during the first stage. High speed thermographic recording of the temperature distribution in the test sample during laser ignition makes it possible to calculate the heat content at any instant. Thus, one can actually observe laser heating and the onset of self-sustained combustion in the pellet

  5. Ignition Delay Studies on Hypergolic Fuel Grains

    Directory of Open Access Journals (Sweden)

    S. R. Jain

    1988-07-01

    Full Text Available The ignition delays of several solid hypergolic fuel compositions, casted using various polymeric binders, or as melts, have been determined with fuming nitric acid as oxidizer. The ignition delays of various hypergolic fuel compositions increase drasticaliy on casting with binders like. carboxyl or hydroxyl termninated polybutadiene. Fuel grains cast using some newly syhthesised epoxy  resins with other ingrcdients, such as curing agent, magnesium powder and fuel, have short ignition delays of the order of 200 ms, and also good mechanical strength. Increasing the amount of binder in the composition retards the hypergolicity of the rain. Similar studies have been made on melt-cast systems using low melting hypergolic fuels for casting fuel powders. The ignition delays of the melt-cast grains, are longer than those determined taking the composition in the powder form. The effect of highly hypergolic additives, and metal powders, on the ignition delay of the cast compositions has been determined. Grains having good mechanical strength and short ignition delays have been obtained by optimising the fuel grain composition.

  6. Implosion dynamics measurements at the National Ignition Facility

    International Nuclear Information System (INIS)

    Measurements have been made of the in-flight dynamics of imploding capsules indirectly driven by laser energies of 1–1.7 MJ at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)]. These experiments were part of the National Ignition Campaign [Landen et al., Phys. Plasmas 18, 051002 (2011)] to iteratively optimize the inputs required to achieve thermonuclear ignition in the laboratory. Using gated or streaked hard x-ray radiography, a suite of ablator performance parameters, including the time-resolved radius, velocity, mass, and thickness, have been determined throughout the acceleration history of surrogate gas-filled implosions. These measurements have been used to establish a dynamically consistent model of the ablative drive history and shell compressibility throughout the implosion trajectory. First results showed that the peak velocity of the original 1.3-MJ Ge-doped polymer (CH) point design using Au hohlraums reached only 75% of the required ignition velocity. Several capsule, hohlraum, and laser pulse changes were then implemented to improve this and other aspects of implosion performance and a dedicated effort was undertaken to test the sensitivity of the ablative drive to the rise time and length of the main laser pulse. Changing to Si rather than Ge-doped inner ablator layers and increasing the pulse length together raised peak velocity to 93% ± 5% of the ignition goal using a 1.5 MJ, 420 TW pulse. Further lengthening the pulse so that the laser remained on until the capsule reached 30% (rather than 60%–70%) of its initial radius, reduced the shell thickness and improved the final fuel ρR on companion shots with a cryogenic hydrogen fuel layer. Improved drive efficiency was observed using U rather than Au hohlraums, which was expected, and by slowing the rise time of laser pulse, which was not. The effect of changing the Si-dopant concentration and distribution, as well as the effect of using a larger initial shell

  7. Implosion dynamics measurements at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Hicks, D. G.; Meezan, N. B.; Dewald, E. L.; Mackinnon, A. J.; Callahan, D. A.; Doeppner, T.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Di Nicola, P.; Dixit, S. N.; Dzenitis, E. G.; Eggert, J. E.; Farley, D. R.; Glenn, S. M.; Glenzer, S. H.; Hamza, A. V.; Heeter, R. F.; Holder, J. P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

    2012-12-15

    Measurements have been made of the in-flight dynamics of imploding capsules indirectly driven by laser energies of 1-1.7 MJ at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)]. These experiments were part of the National Ignition Campaign [Landen et al., Phys. Plasmas 18, 051002 (2011)] to iteratively optimize the inputs required to achieve thermonuclear ignition in the laboratory. Using gated or streaked hard x-ray radiography, a suite of ablator performance parameters, including the time-resolved radius, velocity, mass, and thickness, have been determined throughout the acceleration history of surrogate gas-filled implosions. These measurements have been used to establish a dynamically consistent model of the ablative drive history and shell compressibility throughout the implosion trajectory. First results showed that the peak velocity of the original 1.3-MJ Ge-doped polymer (CH) point design using Au hohlraums reached only 75% of the required ignition velocity. Several capsule, hohlraum, and laser pulse changes were then implemented to improve this and other aspects of implosion performance and a dedicated effort was undertaken to test the sensitivity of the ablative drive to the rise time and length of the main laser pulse. Changing to Si rather than Ge-doped inner ablator layers and increasing the pulse length together raised peak velocity to 93% {+-} 5% of the ignition goal using a 1.5 MJ, 420 TW pulse. Further lengthening the pulse so that the laser remained on until the capsule reached 30% (rather than 60%-70%) of its initial radius, reduced the shell thickness and improved the final fuel {rho}R on companion shots with a cryogenic hydrogen fuel layer. Improved drive efficiency was observed using U rather than Au hohlraums, which was expected, and by slowing the rise time of laser pulse, which was not. The effect of changing the Si-dopant concentration and distribution, as well as the effect of using a larger initial shell

  8. Implosion dynamics measurements at the National Ignition Facility

    Science.gov (United States)

    Hicks, D. G.; Meezan, N. B.; Dewald, E. L.; Mackinnon, A. J.; Olson, R. E.; Callahan, D. A.; Döppner, T.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Di Nicola, P.; Dixit, S. N.; Dzenitis, E. G.; Eggert, J. E.; Farley, D. R.; Frenje, J. A.; Glenn, S. M.; Glenzer, S. H.; Hamza, A. V.; Heeter, R. F.; Holder, J. P.; Izumi, N.; Kalantar, D. H.; Khan, S. F.; Kline, J. L.; Kroll, J. J.; Kyrala, G. A.; Ma, T.; MacPhee, A. G.; McNaney, J. M.; Moody, J. D.; Moran, M. J.; Nathan, B. R.; Nikroo, A.; Opachich, Y. P.; Petrasso, R. D.; Prasad, R. R.; Ralph, J. E.; Robey, H. F.; Rinderknecht, H. G.; Rygg, J. R.; Salmonson, J. D.; Schneider, M. B.; Simanovskaia, N.; Spears, B. K.; Tommasini, R.; Widmann, K.; Zylstra, A. B.; Collins, G. W.; Landen, O. L.; Kilkenny, J. D.; Hsing, W. W.; MacGowan, B. J.; Atherton, L. J.; Edwards, M. J.

    2012-12-01

    Measurements have been made of the in-flight dynamics of imploding capsules indirectly driven by laser energies of 1-1.7 MJ at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)]. These experiments were part of the National Ignition Campaign [Landen et al., Phys. Plasmas 18, 051002 (2011)] to iteratively optimize the inputs required to achieve thermonuclear ignition in the laboratory. Using gated or streaked hard x-ray radiography, a suite of ablator performance parameters, including the time-resolved radius, velocity, mass, and thickness, have been determined throughout the acceleration history of surrogate gas-filled implosions. These measurements have been used to establish a dynamically consistent model of the ablative drive history and shell compressibility throughout the implosion trajectory. First results showed that the peak velocity of the original 1.3-MJ Ge-doped polymer (CH) point design using Au hohlraums reached only 75% of the required ignition velocity. Several capsule, hohlraum, and laser pulse changes were then implemented to improve this and other aspects of implosion performance and a dedicated effort was undertaken to test the sensitivity of the ablative drive to the rise time and length of the main laser pulse. Changing to Si rather than Ge-doped inner ablator layers and increasing the pulse length together raised peak velocity to 93% ± 5% of the ignition goal using a 1.5 MJ, 420 TW pulse. Further lengthening the pulse so that the laser remained on until the capsule reached 30% (rather than 60%-70%) of its initial radius, reduced the shell thickness and improved the final fuel ρR on companion shots with a cryogenic hydrogen fuel layer. Improved drive efficiency was observed using U rather than Au hohlraums, which was expected, and by slowing the rise time of laser pulse, which was not. The effect of changing the Si-dopant concentration and distribution, as well as the effect of using a larger initial shell thickness

  9. First downscattered neutron images from Inertial Confinement Fusion experiments at the National Ignition Facility

    International Nuclear Information System (INIS)

    Inertial Confinement Fusion experiments at the National Ignition Facility (NIF) are designed to understand and test the basic principles of self-sustaining fusion reactions by laser driven compression of deuterium-tritium (DT) filled cryogenic plastic (CH) capsules. The experimental campaign is ongoing to tune the implosions and characterize the burning plasma conditions. Nuclear diagnostics play an important role in measuring the characteristics of these burning plasmas, providing feedback to improve the implosion dynamics. The Neutron Imaging (NI) diagnostic provides information on the distribution of the central fusion reaction region and the surrounding DT fuel by collecting images at two different energy bands for primary (13-15 MeV) and downscattered (10-12 MeV) neutrons. From these distributions, the final shape and size of the compressed capsule can be estimated and the symmetry of the compression can be inferred. The first downscattered neutron images from imploding ICF capsules are shown in this paper. (authors)

  10. First downscattered neutron images from Inertial Confinement Fusion experiments at the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Guler Nevzat

    2013-11-01

    Full Text Available Inertial Confinement Fusion experiments at the National Ignition Facility (NIF are designed to understand and test the basic principles of self-sustaining fusion reactions by laser driven compression of deuterium-tritium (DT filled cryogenic plastic (CH capsules. The experimental campaign is ongoing to tune the implosions and characterize the burning plasma conditions. Nuclear diagnostics play an important role in measuring the characteristics of these burning plasmas, providing feedback to improve the implosion dynamics. The Neutron Imaging (NI diagnostic provides information on the distribution of the central fusion reaction region and the surrounding DT fuel by collecting images at two different energy bands for primary (13–15 MeV and downscattered (10–12 MeV neutrons. From these distributions, the final shape and size of the compressed capsule can be estimated and the symmetry of the compression can be inferred. The first downscattered neutron images from imploding ICF capsules are shown in this paper.

  11. Comparison of the Recently proposed Super Marx Generator Approach to Thermonuclear Ignition with the DT Laser Fusion-Fission Hybrid Concept by the Lawrence Livermore National Laboratory

    OpenAIRE

    Winterberg, Friedwardt

    2009-01-01

    The recently proposed Super Marx generator pure deuterium micro-detonation ignition concept is compared to the Lawrence Livermore National Ignition Facility (NIF) Laser DT fusion-fission hybrid concept (LiFE) [1]. In a Super Marx generator a large number of ordinary Marx generators charge up a much larger second stage ultra-high voltage Marx generator, from which for the ignition of a pure deuterium micro-explosion an intense GeV ion beam can be extracted. A typical example of the LiFE concep...

  12. Study of suprathermal electron transport in solid or compressed matter for the fast-ignitor scheme.

    OpenAIRE

    Pérez, Frédéric

    2010-01-01

    The inertial confinement fusion (ICF) concept is widely studied nowadays. It consists in quickly compressing and heating a small spherical capsule filled with fuel, using extremely energetic lasers. Since approximately 15 years, the fast-ignition (FI) technique has been proposed to facilitate the fuel heating by adding a particle beam - electrons generated by an ultra-intense laser - at the exact moment when the capsule compression is at its maximum. This thesis constitutes an experimental st...

  13. A Hybrid Ion/Electron Beam Fast Ignition Concept

    Science.gov (United States)

    Albright, B. J.

    2009-11-01

    Fast ignition (FI) inertial confinement fusion is an approach to high-gain inertial fusion, whereby a dense core of deuterium/tritium fuel is assembled via direct or indirect drive and then a hot spot within the core is heated rapidly (over a time scale of order 10 ps) to ignition conditions by beams of fast charged particles. These particle beams are generated outside the capsule by the interaction of ultra-intense laser pulses with solid density targets. Most study of FI to date has focused on the use of electron [Tabak et al., Phys. Plasmas 1, 1696 (1994)] or ion [Fern'andez et al., Nuclear Fusion 49, 065004 (2009)] beams, however a hybrid approach involving both may have advantages. This paper will describe recent work in this arena. Work performed under the auspices of the U. S. Dept. of Energy by the Los Alamos National Security, Los Alamos National Laboratory. This work was supported by LANL Laboratory Directed Research and Development (LDRD).

  14. Energy gain of ignitable targets in inertial confinement fusion (ICF

    Directory of Open Access Journals (Sweden)

    A. Parvazian,J Jafari

    2002-06-01

    Full Text Available   In order to determine the fusion energy gain in a target due to inertial confinement fusion, it is necessary to solve hydrodynamic equations governed on plasma behavior during confinement time. To compress spherical multilayer targets having fuel in the central part, they are irradiated by laser or heavy ion beams. A suitable mass ratio of a pusher is used to ignite the central part of the target. When compression is maximum, fuel density exceeds from 500 to 1000 times of the cold density. Temperature in the cold fuel region rises rapidly and cause the plasma and fusion reaction to take place. Calculations of density, temperature and pressure profiles in the plasma are necessary to obtain the energy flux of neurons, electrons and radiations coming out from the target. Using numerical solutions for continuity, the momentum and energy equations based on a defined continuity equation we prepared a computer program to calculate density, temperature and pressure profiles. The gain of the target as output to input energy is determined. Using this procedure to a designed target with deuterium-tritium (DT fuel derived by heavy ion beams gives an energy gain over 400.

  15. The National Ignition Facility: Enabling Fusion Ignition for the 21st Century

    Energy Technology Data Exchange (ETDEWEB)

    Moses, E I; Miller, G H; Wuest, C R

    2004-09-17

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, when completed in 2008, will contain a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter-diameter target chamber and room for 100 diagnostics. NIF is housed in a 26,000 square meter environmentally controlled building and is the world's largest and most energetic laser experimental system. NIF provides a scientific center for the study of inertial confinement fusion and the physics of matter at extreme energy densities and pressures. NIF's energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will study physical processes at temperatures approaching 10{sup 8} K and 10{sup 11} bar; conditions that exist naturally only in the interior of stars and planets. NIF is currently configured with four laser beams activated in late 2002. These beams are being regularly used for laser performance and physics experiments and to date nearly 250 system shots have been conducted. NIF's laser beams have generated 106 kilojoules in 23-ns pulses of infrared light and over 16 kJ in 3.5-ns pulses at the third harmonic (351 nm). A number of target experimental systems are being commissioned in support of experimental campaigns. This paper provides a detailed look the NIF laser systems, laser and optical performance, and results from laser commissioning shots. We also discuss NIF's high -energy density and inertial fusion experimental capabilities, the first experiments on NIF, and plans for future capabilities of this unique facility.

  16. Aerospace Laser Ignition/Ablation Variable High Precision Thruster

    Science.gov (United States)

    Campbell, Jonathan W. (Inventor); Edwards, David L. (Inventor); Campbell, Jason J. (Inventor)

    2015-01-01

    A laser ignition/ablation propulsion system that captures the advantages of both liquid and solid propulsion. A reel system is used to move a propellant tape containing a plurality of propellant material targets through an ignition chamber. When a propellant target is in the ignition chamber, a laser beam from a laser positioned above the ignition chamber strikes the propellant target, igniting the propellant material and resulting in a thrust impulse. The propellant tape is advanced, carrying another propellant target into the ignition chamber. The propellant tape and ignition chamber are designed to ensure that each ignition event is isolated from the remaining propellant targets. Thrust and specific impulse may by precisely controlled by varying the synchronized propellant tape/laser speed. The laser ignition/ablation propulsion system may be scaled for use in small and large applications.

  17. Technical evaluation of vehicle ignition systems: conduct differences between a high energy capacitive system and a standard inductive system

    Directory of Open Access Journals (Sweden)

    Bruno Santos Goulart

    2014-09-01

    Full Text Available An efficient combustion depends on many factors, such as injection, turbulence and ignition characteristics. With the improvement of internal combustion engines the turbulence intensity and internal pressure have risen, demanding more efficient and powerful ignition systems. In direct injection engines, the stratified charge resultant from the wall/air-guided or spray-guided system requires even more energy. The Paschen’s law shows that spark plug gap and mixture density are proportional to the dielectric rupture voltage. It is known that larger spark gaps promote higher efficiency in the internal combustion engines, since the mixture reaction rate rises proportionally. However, the ignition system must be adequate to the imposed gap, not only on energy, but also on voltage and spark duration. For the reported study in this work two test benches were built: a standard inductive ignition system and a capacitive discharge high energy ignition system, with variable voltage and capacitance. The influence of the important parameters energy and ignition voltage on the spark duration, as well as the electrode gap and shape were analyzed. It was also investigated the utilization of a coil with lower resistance and inductance values, as well as spark plugs with and without internal resistances.

  18. Spontaneously Igniting Hybrid Fuel-Oxidiser Systems

    Directory of Open Access Journals (Sweden)

    S. R. Jain

    1995-01-01

    Full Text Available After briefly outlining the recent developments in hybrid rockets, the work carried out by the author on self-igniting (hypergolic solid fuel-liquid oxidiser systems has been reviewed. A major aspect relates to the solid derivatives of hydrazines, which have been conceived as fuels for hybrid rockets. Many of these N-N bonded compounds ignite readily, with very short ignition delays, on coming into contact with liquid oxidisers, like HNO/sub 3/ and N/sub 2/ O/sub 4/. The ignition characteristics have been examined as a function of the nature of the functional group in the fuel molecule, in an attempt to establish a basis for the hypergolic ignition in terms of chemical reactivity of the fuel-oxidiser combination. Important chemical reactions occurring in the pre-ignition stage have been identified by examining the quenched reaction products. Hybrid systems exhibiting synergistic hypergolicity in the presence of metal powders have investigated. An estimation of the rocket performance parameters, experimental determination of the heats of combustion in HNO/sub 3/, thermal decomposition characteristics, temperature profile by thin film thermometry and product identification by the rapid scan FT-IR, are among the other relevant studies made on these systems. A significant recent development has been the synthesis of new N-N bonded viscous binders, capable of rataining the hypergolicity of the fuel powders embedded therein as well as providing the required mechanical strength to the grain. Several of these resins have been characterised. Metallised fuel composites of these resins having high loading of magnesium are found to have short ignition delays and high performance parameters.

  19. Recent developments in ignition target design for the National Ignition Facility

    International Nuclear Information System (INIS)

    Work on design of ignition targets for the National Ignition Facility (NIF) has progressed in three areas. First, hohlraums have been re-optimized taking advantage of improvements in efficiency in several areas: use of high albedo material mixtures in the hohlraum wall; optimizing the laser entrance hole; optimizing the case-to-capsule ratio; and taking advantage of increased efficiency of longer pulses. These changes, in combination, allow for the possibility of quite high yields (∼100MJ), gains (>40) and significantly more margin for ignition on NIF. Second, work has continued on specifications for target fabrication. Third, detailed design and analysis has been done on targets for the commissioning phase of NIF, when only 96 beams are available. We find excellent hydrodynamic similarity is possible with sub-scale cryogenic targets. These targets can be used to test all of the physics of full-scale ignition targets in detail except, perhaps, for ignition itself. (author)

  20. Determination of optimum proton pulse duration for triggering fast ignition in inertial confinement fusion

    Directory of Open Access Journals (Sweden)

    A. Ghasemizad

    2007-03-01

    Full Text Available  Two relatively simple analytic Models for investigation of fast ignition dynamics are developed, that are the subsonic and the supersonic models. On the basis of the subsonic model, which a pre-compressed fuel of density is heated by a subsonic thermal wave, the beam energy and the intensity required for ignition is closely related to proton range. Whereas, on the basis of supersonic model, for ranges shorter than 0.25 gr/cm2 , the mentioned energy remains constant and the intensity decreases. For ranges larger than this value, not only energy but also the beam intensity will increase with the proton range. Considering that proton pulse duration depend on proton range implicitly, these results allow for the determination of an optimum proton pulse duration value, that we have obtained this value equal to 2.14×103 po-1  ps.

  1. Drift compression of an intense neutralized ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Roy, P.K.; Yu, S.S.; Henestroza, E.; Anders, A.; Bieniosek, F.M.; Coleman, J.; Eylon, S.; Greenway, W.G.; Leitner, M.; Logan, B.G.; Waldron, W.L.; Welch, D.R.; Thoma, C.; Sefkow, A.B.; Gilson, E.P.; Efthimion, P.C.; Davidson, R.C.

    2004-10-25

    Longitudinal compression of a tailored-velocity, intense neutralized ion beam has been demonstrated. The compression takes place in a 1-2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhancing the beam peak current by a factor of 50 and producing a pulse duration of about 3 ns. this measurement has been confirmed independently with two different diagnostic systems.

  2. Learning in compressed space.

    Science.gov (United States)

    Fabisch, Alexander; Kassahun, Yohannes; Wöhrle, Hendrik; Kirchner, Frank

    2013-06-01

    We examine two methods which are used to deal with complex machine learning problems: compressed sensing and model compression. We discuss both methods in the context of feed-forward artificial neural networks and develop the backpropagation method in compressed parameter space. We further show that compressing the weights of a layer of a multilayer perceptron is equivalent to compressing the input of the layer. Based on this theoretical framework, we will use orthogonal functions and especially random projections for compression and perform experiments in supervised and reinforcement learning to demonstrate that the presented methods reduce training time significantly. PMID:23501172

  3. Time-resolved measurements of the hot-electron population in ignition-scale experiments on the National Ignition Facility (invited).

    Science.gov (United States)

    Hohenberger, M; Albert, F; Palmer, N E; Lee, J J; Döppner, T; Divol, L; Dewald, E L; Bachmann, B; MacPhee, A G; LaCaille, G; Bradley, D K; Stoeckl, C

    2014-11-01

    In laser-driven inertial confinement fusion, hot electrons can preheat the fuel and prevent fusion-pellet compression to ignition conditions. Measuring the hot-electron population is key to designing an optimized ignition platform. The hot electrons in these high-intensity, laser-driven experiments, created via laser-plasma interactions, can be inferred from the bremsstrahlung generated by hot electrons interacting with the target. At the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)], the filter-fluorescer x-ray (FFLEX) diagnostic-a multichannel, hard x-ray spectrometer operating in the 20-500 keV range-has been upgraded to provide fully time-resolved, absolute measurements of the bremsstrahlung spectrum with ∼300 ps resolution. Initial time-resolved data exhibited significant background and low signal-to-noise ratio, leading to a redesign of the FFLEX housing and enhanced shielding around the detector. The FFLEX x-ray sensitivity was characterized with an absolutely calibrated, energy-dispersive high-purity germanium detector using the high-energy x-ray source at NSTec Livermore Operations over a range of K-shell fluorescence energies up to 111 keV (U Kβ). The detectors impulse response function was measured in situ on NIF short-pulse (∼90 ps) experiments, and in off-line tests. PMID:25430175

  4. Time-resolved measurements of the hot-electron population in ignition-scale experiments on the National Ignition Facility (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Hohenberger, M., E-mail: mhoh@lle.rochester.edu; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Albert, F.; Palmer, N. E.; Döppner, T.; Divol, L.; Dewald, E. L.; Bachmann, B.; MacPhee, A. G.; LaCaille, G.; Bradley, D. K. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Lee, J. J. [National Security Technologies LLC, Livermore, California 94551 (United States)

    2014-11-15

    In laser-driven inertial confinement fusion, hot electrons can preheat the fuel and prevent fusion-pellet compression to ignition conditions. Measuring the hot-electron population is key to designing an optimized ignition platform. The hot electrons in these high-intensity, laser-driven experiments, created via laser-plasma interactions, can be inferred from the bremsstrahlung generated by hot electrons interacting with the target. At the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)], the filter-fluorescer x-ray (FFLEX) diagnostic–a multichannel, hard x-ray spectrometer operating in the 20–500 keV range–has been upgraded to provide fully time-resolved, absolute measurements of the bremsstrahlung spectrum with ∼300 ps resolution. Initial time-resolved data exhibited significant background and low signal-to-noise ratio, leading to a redesign of the FFLEX housing and enhanced shielding around the detector. The FFLEX x-ray sensitivity was characterized with an absolutely calibrated, energy-dispersive high-purity germanium detector using the high-energy x-ray source at NSTec Livermore Operations over a range of K-shell fluorescence energies up to 111 keV (U K{sub β}). The detectors impulse response function was measured in situ on NIF short-pulse (∼90 ps) experiments, and in off-line tests.

  5. Volume ignition of inertial confinement fusion of deuterium-helium(3) and hydrogen-boron(11) clean fusion fuel

    International Nuclear Information System (INIS)

    Since DT laser fusion with 10-MJ laser pulses for 1000-MJ output now offers the physics solution for an economical fusion energy reactor, the conditions are evaluated assuming that controlled ICF reactions will become possible in the future using clean nuclear fusion fuel such as deuterium-helium(3) or hydrogen-boron(11). Using the transparent physics mechanisms of volume ignition of the fuel capsules, it is shown that the volume ignition for strong reduction of the optimum initial temperature can be reached for both types of fuel if a compression about 100 times higher than those in present-day laser compression experiments is attained in the future. Helium(3) laser-pulse energies are then in the same range as for DT, but ten times higher energies will be required for hydrogen-boron(11). (Author)

  6. Dark Matter Ignition of Type Ia Supernovae.

    Science.gov (United States)

    Bramante, Joseph

    2015-10-01

    Recent studies of low redshift type Ia supernovae (SN Ia) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SN Ia progenitors. We show that 1-100 PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SN Ia. We combine data on SN Ia masses with data on the ages of SN Ia-adjacent stars. This combination reveals a 2.8σ inverse correlation between SN Ia masses and ignition ages, which could result from increased capture of dark matter in 1.4 vs 1.1 solar mass white dwarfs. Future studies of SN Ia in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SN Ia-igniting dark matter also resolve the missing pulsar problem by forming black holes in ≳10  Myr old pulsars at the center of the Milky Way. PMID:26551803

  7. Plasma transport in a Compact Ignition Tokamak

    International Nuclear Information System (INIS)

    Nominal predicted plasma conditions in a Compact Ignition Tokamak (CIT) are illustrated by transport simulations using experimentally calibrated plasma transport models. The range of uncertainty in these predictions is explored by using various models that have given almost equally good fits to experimental data. Using a transport model that best fits the data, thermonuclear ignition occurs in a CIT design with a major radius of 1.32 m, plasma half-width of 0.43 mn, elongation of 2.0, and toroidal field and plasma current ramped in 6 s from 1.7 to 10.4 T and 0.7 to 10 MA, respectively. Ignition is facilitated by 20 MW of heating deposited off the magnetic axis near the /sup 3/He minority cyclotron resonance layer. Under these conditions, sawtooth oscillations are small and have little impact on ignition. Tritium inventory is minimized by preconditioning most discharges with deuterium. Tritium is injected, in large frozen pellets, only after minority resonance preheating. Variations of the transport model, impurity influx, heating profile, and pellet ablation rates have a large effect on ignition and on the maximum beta that can be achieved

  8. Physics aspects of the compact ignition tokamak

    International Nuclear Information System (INIS)

    The Compact Ignition Tokamak (CIT) is a proposed modest-size ignition experiment designed to study the physics of alpha particle heating. The basic concept is to achieve ignition in a modest-size minimum cost experiment by using a high plasma density to achieve nτE ≅ 2 x 1020 s/m3 required for ignition. The high density requires a high toroidal field (10 T). The high toroidal field allows a large plasma current (10 MA) which provides a high level of ohmic heating, improves the energy confinement, and allows a relatively high beta (≅ 6%). The present CIT design also has a high degree of elongation (κ ≅ 1.8) to aid in producing the large plasma current. A double null poloidal divertor and pellet injection are part of the design to provide impurity and particle control, improve the confinement, and provide flexibility for improving the plasma profiles. Auxiliary heating is expected to be necessary to achieve ignition, and 10-20 MW of ICRF is to be provided. (orig.)

  9. Physics aspects of the Compact Ignition Tokamak

    International Nuclear Information System (INIS)

    The Compact Ignition Tokamak (CIT) is a proposed modest-size ignition experiment designed to study the physics of alpha-particle heating. The basic concept is to achieve ignition in a modest-size minimum cost experiment by using a high plasma density to achieve the condition of ntau/sub E/ ∼ 2 x 1020 sec m-3 required for ignition. The high density requires a high toroidal field (10 T). The high toroidal field allows a large plasma current (10 MA) which improves the energy confinement, and provides a high level of ohmic heating. The present CIT design also has a gigh degree of elongation (k ∼ 1.8) to aid in producing the large plasma current. A double null poloidal divertor and a pellet injector are part of the design to provide impurity and particle control, improve the confinement, and provide flexibility for impurity and particle control, improve the confinement, and provide flexibility for improving the plasma profiles. Since auxiliary heating is expected to be necessary to achieve ignition, 10 to 20 MW of Ion Cyclotron Radio Frequency (ICRF) is to be provided

  10. Low power arcjet thruster pulse ignition

    Science.gov (United States)

    Sarmiento, Charles J.; Gruber, Robert P.

    1987-01-01

    An investigation of the pulse ignition characteristics of a 1 kW class arcjet using an inductive energy storage pulse generator with a pulse width modulated power converter identified several thruster and pulse generator parameters that influence breakdown voltage including pulse generator rate of voltage rise. This work was conducted with an arcjet tested on hydrogen-nitrogen gas mixtures to simulate fully decomposed hydrazine. Over all ranges of thruster and pulser parameters investigated, the mean breakdown voltages varied from 1.4 to 2.7 kV. Ignition tests at elevated thruster temperatures under certain conditions revealed occasional breakdowns to thruster voltages higher than the power converter output voltage. These post breakdown discharges sometimes failed to transition to the lower voltage arc discharge mode and the thruster would not ignite. Under the same conditions, a transition to the arc mode would occur for a subsequent pulse and the thruster would ignite. An automated 11 600 cycle starting and transition to steady state test demonstrated ignition on the first pulse and required application of a second pulse only two times to initiate breakdown.

  11. Physics aspects of the Compact Ignition Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Post, D.; Bateman, G.; Houlberg, W.; Bromberg, L.; Cohn, D.; Colestock, P.; Hughes, M.; Ignat, D.; Izzo, R.; Jardin, S.

    1986-11-01

    The Compact Ignition Tokamak (CIT) is a proposed modest-size ignition experiment designed to study the physics of alpha-particle heating. The basic concept is to achieve ignition in a modest-size minimum cost experiment by using a high plasma density to achieve the condition of ntau/sub E/ approx. 2 x 10/sup 20/ sec m/sup -3/ required for ignition. The high density requires a high toroidal field (10 T). The high toroidal field allows a large plasma current (10 MA) which improves the energy confinement, and provides a high level of ohmic heating. The present CIT design also has a gigh degree of elongation (k approx. 1.8) to aid in producing the large plasma current. A double null poloidal divertor and a pellet injector are part of the design to provide impurity and particle control, improve the confinement, and provide flexibility for impurity and particle control, improve the confinement, and provide flexibility for improving the plasma profiles. Since auxiliary heating is expected to be necessary to achieve ignition, 10 to 20 MW of Ion Cyclotron Radio Frequency (ICRF) is to be provided.

  12. Direct-drive inertial confinement fusion research at the Laboratory for Laser Energetics: Charting the path to thermonuclear ignition

    International Nuclear Information System (INIS)

    Significant theoretical and experimental progress continues to be made at the University of Rochester's Laboratory for Laser Energetics (LLE), charting the path to direct-drive ignition. Direct-drive inertial confinement fusion (ICF) offers the potential for higher-gain implosions than x-ray drive and is a leading candidate for an inertial fusion energy power plant. LLE's direct-drive ICF ignition target designs for the National Ignition Facility (NIF) are based on hot-spot ignition. A cryogenic target with a spherical DT-ice layer, within or without a foam matrix, enclosed by a thin plastic shell, is directly irradiated with ∼1.5 MJ of laser energy. Cryogenic and plastic/ foam (surrogate-cryogenic) targets that are hydrodynamically scaled from ignition target designs are imploded on the OMEGA 60-beam, 30-kJ, UV laser system to investigate the key target physics issues of energy coupling, hydrodynamic instabilities, and implosion symmetry. Cryogenic D2-ice-layer finishes approaching the 1-μm NIF requirement have been produced. Prospects for direct-drive ignition on the NIF are extremely favorable, even while it is configured in its x-ray-drive irradiation configuration with polar direct-drive (PDD). A high-energy petawatt capability is being constructed at LLE next to the existing 60-beam OMEGA compression facility. The OMEGA EP (extended performance) laser will add two short-pulse, 2- to 3-PW, 2.6-kJ beams to the OMEGA laser system to study fast-ignition physics with focused intensities up to 6 x 1020 W/cm2. (author)

  13. The National Ignition Facility Neutron Imaging System

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF) is scheduled to begin deuterium-tritium (DT) shots possibly in the next several years. One of the important diagnostics in understanding capsule behavior and to guide changes in Hohlraum illumination, capsule design, and geometry will be neutron imaging of both the primary 14 MeV neutrons and the lower-energy downscattered neutrons in the 6-13 MeV range. The neutron imaging system (NIS) described here, which we are currently building for use on NIF, uses a precisely aligned set of apertures near the target to form the neutron images on a segmented scintillator. The images are recorded on a gated, intensified charge coupled device. Although the aperture set may be as close as 20 cm to the target, the imaging camera system will be located at a distance of 28 m from the target. At 28 m the camera system is outside the NIF building. Because of the distance and shielding, the imager will be able to obtain images with little background noise. The imager will be capable of imaging downscattered neutrons from failed capsules with yields Yn>1014 neutrons. The shielding will also permit the NIS to function at neutron yields >1018, which is in contrast to most other diagnostics that may not work at high neutron yields. The following describes the current NIF NIS design and compares the predicted performance with the NIF specifications that must be satisfied to generate images that can be interpreted to understand results of a particular shot. The current design, including the aperture, scintillator, camera system, and reconstruction methods, is briefly described. System modeling of the existing Omega NIS and comparison with the Omega data that guided the NIF design based on our Omega results is described. We will show NIS model calculations of the expected NIF images based on component evaluations at Omega. We will also compare the calculated NIF input images with those unfolded from the NIS images generated from our NIS numerical modeling

  14. Developing the Physics Basis of Fast Ignition Experiments at Future Large Fusion-class lasers

    International Nuclear Information System (INIS)

    The Fast Ignition (FI) concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy (IFE) reactors. FI differs from conventional 'central hot spot' (CHS) target ignition by using one driver (laser, heavy ion beam or Z-pinch) to create a dense fuel and a separate ultra-short, ultra-intense laser beam to ignite the dense core. FI targets can burn with ∼ 3X lower density fuel than CHS targets, resulting in (all other things being equal) lower required compression energy, relaxed drive symmetry, relaxed target smoothness tolerances, and, importantly, higher gain. The short, intense ignition pulse that drives this process interacts with extremely high energy density plasmas; the physics that controls this interaction is only now becoming accessible in the lab, and is still not well understood. The attraction of obtaining higher gains in smaller facilities has led to a worldwide explosion of effort in the studies of FI. In particular, two new US facilities to be completed in 2009/2010, OMEGA/OMEGA EP and NIF-ARC (as well as others overseas) will include FI investigations as part of their program. These new facilities will be able to approach FI conditions much more closely than heretofore using direct drive (dd) for OMEGA/OMEGA EP and indirect drive (id) for NIF-ARC. This LDRD has provided the physics basis for the development of the detailed design for integrated Fast ignition experiments on these facilities on the 2010/2011 timescale. A strategic initiative LDRD has now been formed to carry out integrated experiments using NIF ARC beams to heat a full scale FI assembled core by the end of 2010

  15. A Compressive Superresolution Display

    KAUST Repository

    Heide, Felix

    2014-06-22

    In this paper, we introduce a new compressive display architecture for superresolution image presentation that exploits co-design of the optical device configuration and compressive computation. Our display allows for superresolution, HDR, or glasses-free 3D presentation.

  16. 75 FR 61820 - Model Specifications for Breath Alcohol Ignition Interlock Devices (BAIIDs)

    Science.gov (United States)

    2010-10-06

    ... Specifications for Breath Alcohol Ignition Interlock Devices (BAIIDs). (57 FR 11772.) Ignition interlocks are... National Highway Traffic Safety Administration Model Specifications for Breath Alcohol Ignition Interlock... Breath Alcohol Ignition Interlock Devices (BAIIDs). The Model Specifications are guidelines for...

  17. Compressing Binary Decision Diagrams

    CERN Document Server

    Hansen, Esben Rune; Tiedemann, Peter

    2008-01-01

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1-2 bits per node. Empirical results for our compression technique are presented, including comparisons with previously introduced techniques, showing that the new technique dominate on all tested instances.

  18. Microbunching and RF Compression

    International Nuclear Information System (INIS)

    Velocity bunching (or RF compression) represents a promising technique complementary to magnetic compression to achieve the high peak current required in the linac drivers for FELs. Here we report on recent progress aimed at characterizing the RF compression from the point of view of the microbunching instability. We emphasize the development of a linear theory for the gain function of the instability and its validation against macroparticle simulations that represents a useful tool in the evaluation of the compression schemes for FEL sources.

  19. The National Ignition Facility and industry

    International Nuclear Information System (INIS)

    The mission of the National Ignition Facility is to achieve ignition and gain in inertial confinement fusion targets in the laboratory. The facility will be used for defense applications such as weapons physics and weapons effects testing, and for civilian applications such as fusion energy development and fundamental studies of matter at high temperatures and densities. The National Ignition Facility construction project will require the best of national construction industries and its success will depend on the best products offered by hundreds of the nation's high technology companies. Three-fourths of the construction costs will be invested in industry. This article reviews the design, cost and schedule, and required industrial involvement associated with the construction project

  20. Laser driver beam combination for fast ignition

    International Nuclear Information System (INIS)

    Based on the estimated parameters of fast ignition,the requirements for laser-beam power intensity and energy are used to analyze the possibility of realizing fast ignition by coherent combination and non-coherent combination. The practical distorted wavefront is considered to analyze the far-field focal spot. Non-coherent combination needs more beams for energy requirement and to limit angle drifting in ±2 μrad through improving laser driver's stability. Coherent combination is beneficial for achieving smaller focal spot and higher power intensity, simultaneously reducing the requirement of energy, but single beam wavefront correction can not improve the power intensity in this method, which leads to combined wavefront correction of the total clear aperture with complex monitoring and control methods. Based on the requirement of parameters and wavefront correction capability, non-coherent beam combination is easier to achieve for fast ignition, however, coherent beam combination has the potential for extensive application. (authors)

  1. Ignition threshold for non-Maxwellian plasmas

    CERN Document Server

    Hay, Michael J

    2015-01-01

    An optically thin $p$-$^{11}$B plasma loses more energy to bremsstrahlung than it gains from fusion reactions, unless the ion temperature can be elevated above the electron temperature. In thermal plasmas, the temperature differences required are possible in small Coulomb logarithm regimes, characterized by high density and low temperature. The minimum Lawson criterion for thermal $p$-$^{11}$B plasmas and the minimum $\\rho R$ required for ICF volume ignition are calculated. Ignition could be reached more easily if the fusion reactivity can be improved with nonthermal ion distributions. To establish an upper bound for this utility, we consider a monoenergetic beam with particle energy selected to maximize the beam- thermal reactivity. Channeling fusion alpha energy to maintain such a beam facilitates ignition at lower densities and $\\rho R$, improves reactivity at constant pressure, and could be used to remove helium ash. The gains realized with a beam thus establish an upper bound for the reductions in igniti...

  2. Progress on LMJ targets for ignition

    Energy Technology Data Exchange (ETDEWEB)

    Cherfils-Clerouin, C; Boniface, C; Bonnefille, M; Fremerye, P; Galmiche, D; Gauthier, P; Giorla, J; Lambert, F; Laffite, S; Liberatore, S; Loiseau, P; Malinie, G; Masse, L; Masson-Laborde, P E; Monteil, M C; Poggi, F; Seytor, P; Wagon, F; Willien, J L, E-mail: catherine.cherfils@cea.f [CEA, DAM, DIF, F-91297 Arpajon (France)

    2010-08-01

    Targets designed to produce ignition on the Laser MegaJoule are presented. The LMJ experimental plans include the attempt of ignition and burn of an ICF capsule with 160 laser beams, delivering up to 1.4MJ and 380TW. New targets needing reduced laser energy with only a small decrease in robustness have then been designed for this purpose. Working specifically on the coupling efficiency parameter, i.e. the ratio of the energy absorbed by the capsule to the laser energy, has led to the design of a rugby-shaped cocktail hohlraum. 1D and 2D robustness evaluations of these different targets shed light on critical points for ignition, that can be traded off by tightening some specifications or by preliminary experimental and numerical tuning experiments.

  3. Progress on LMJ targets for ignition

    Energy Technology Data Exchange (ETDEWEB)

    Cherfils-Clerouin, C; Boniface, C; Bonnefille, M; Dattolo, E; Galmiche, D; Gauthier, P; Giorla, J; Laffite, S; Liberatore, S; Loiseau, P; Malinie, G; Masse, L; Masson-Laborde, P E; Monteil, M C; Poggi, F; Seytor, P; Wagon, F; Willien, J L, E-mail: catherine.cherfils@cea.f [CEA, DAM, DIF, F-91297 Arpajon (France)

    2009-12-15

    Targets designed to produce ignition on the Laser Megajoule (LMJ) are being simulated in order to set specifications for target fabrication. The LMJ experimental plans include the attempt of ignition and burn of an ICF capsule with 160 laser beams, delivering up to 1.4 MJ and 380 TW. New targets needing reduced laser energy with only a small decrease in robustness have then been designed for this purpose. Working specifically on the coupling efficiency parameter, i.e. the ratio of the energy absorbed by the capsule to the laser energy, has led to the design of a rugby-ball shaped cocktail hohlraum; with these improvements, a target based on the 240-beam A1040 capsule can be included in the 160-beam laser energy-power space. Robustness evaluations of these different targets shed light on critical points for ignition, which can trade off by tightening some specifications or by preliminary experimental and numerical tuning experiments.

  4. Ignition Failure Mode Radiochemical Diagnostics Initial Assessment

    International Nuclear Information System (INIS)

    Radiochemical diagnostic signatures are well known to be effective indicators of nuclear ignition and burn reaction conditions. Nuclear activation is already a reliable technique to measure yield. More comprehensively, though, important quantities such as fuel areal density and ion temperature might be separately and more precisely monitored by a judicious choice of select nuclear reactions. This report details an initial assessment of this approach to diagnosing ignition failures on point-design cryogenic National Ignition Campaign targets. Using newly generated nuclear reaction cross section data for Scandium and Iridium, modest uniform doping of the innermost ablator region provides clearly observable reaction product differences between robust burn and failure for either element. Both equatorial and polar tracer loading yield observable, but indistinguishable, signatures for either choice of element for the preliminary cases studied

  5. Ignition of THKP and TKP pyrotechnic powders :

    Energy Technology Data Exchange (ETDEWEB)

    Maharrey, Sean P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Erikson, William W [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Highley, Aaron M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wiese-Smith, Deneille [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kay, Jeffrey J [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-03-01

    We have conducted Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry (STMBMS) experiments on igniter/actuator pyrotechnic powders to characterize the reactive processes controlling the ignition and combustion behavior of these materials. The experiments showed a complex, interactive reaction manifold involving over ten reaction pathways. A reduced dimensionality reaction manifold was developed from the detailed 10-step manifold and is being incorporated into existing predictive modeling codes to simulate the performance of pyrotechnic powders for NW component development. The results from development of the detailed reaction manifold and reduced manifold are presented. The reduced reaction manifold has been successfully used by SNL/NM modelers to predict thermal ignition events in small-scale testing, validating our approach and improving the capability of predictive models.

  6. Target Visualization at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Potter, Daniel Abraham [Univ. of California, Davis, CA (United States)

    2011-01-01

    As the National Ignition Facility continues its campaign to achieve ignition, new methods and tools will be required to measure the quality of the targets used to achieve this goal. Techniques have been developed to measure target surface features using a phase-shifting diffraction interferometer and Leica Microsystems confocal microscope. Using these techniques we are able to produce a detailed view of the shell surface, which in turn allows us to refine target manufacturing and cleaning processes. However, the volume of data produced limits the methods by which this data can be effectively viewed by a user. This paper introduces an image-based visualization system for data exploration of target shells at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. It aims to combine multiple image sets into a single visualization to provide a method of navigating the data in ways that are not possible with existing tools.

  7. Hyperspectral data compression

    CERN Document Server

    Motta, Giovanni; Storer, James A

    2006-01-01

    Provides a survey of results in the field of compression of remote sensed 3D data, with a particular interest in hyperspectral imagery. This work covers topics such as compression architecture, lossless compression, lossy techniques, and more. It also describes a lossless algorithm based on vector quantization.

  8. Compressing Binary Decision Diagrams

    DEFF Research Database (Denmark)

    Hansen, Esben Rune; Satti, Srinivasa Rao; Tiedemann, Peter

    The paper introduces a new technique for compressing Binary Decision Diagrams in those cases where random access is not required. Using this technique, compression and decompression can be done in linear time in the size of the BDD and compression will in many cases reduce the size of the BDD to 1...

  9. Compressible turbulent mixing: Effects of compressibility

    Science.gov (United States)

    Ni, Qionglin

    2016-04-01

    We studied by numerical simulations the effects of compressibility on passive scalar transport in stationary compressible turbulence. The turbulent Mach number varied from zero to unity. The difference in driven forcing was the magnitude ratio of compressive to solenoidal modes. In the inertial range, the scalar spectrum followed the k-5 /3 scaling and suffered negligible influence from the compressibility. The growth of the Mach number showed (1) a first reduction and second enhancement in the transfer of scalar flux; (2) an increase in the skewness and flatness of the scalar derivative and a decrease in the mixed skewness and flatness of the velocity-scalar derivatives; (3) a first stronger and second weaker intermittency of scalar relative to that of velocity; and (4) an increase in the intermittency parameter which measures the intermittency of scalar in the dissipative range. Furthermore, the growth of the compressive mode of forcing indicated (1) a decrease in the intermittency parameter and (2) less efficiency in enhancing scalar mixing. The visualization of scalar dissipation showed that, in the solenoidal-forced flow, the field was filled with the small-scale, highly convoluted structures, while in the compressive-forced flow, the field was exhibited as the regions dominated by the large-scale motions of rarefaction and compression.

  10. National Ignition Facility Target Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Wavrik, R W; Cox, J R; Fleming, P J

    2000-10-05

    On June 11, 1999 the Department of Energy dedicated the single largest piece of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in Livermore, California. The ten (10) meter diameter aluminum target high vacuum chamber will serve as the working end of the largest laser in the world. The output of 192 laser beams will converge at the precise center of the chamber. The laser beams will enter the chamber in two by two arrays to illuminate 10 millimeter long gold cylinders called hohlraums enclosing 2 millimeter capsule containing deuterium, tritium and isotopes of hydrogen. The two isotopes will fuse, thereby creating temperatures and pressures resembling those found only inside stars and in detonated nuclear weapons, but on a minute scale. The NIF Project will serve as an essential facility to insure safety and reliability of our nation's nuclear arsenal as well as demonstrating inertial fusion's contribution to creating electrical power. The paper will discuss the requirements that had to be addressed during the design, fabrication and testing of the target chamber. A team from Sandia National Laboratories (SNL) and LLNL with input from industry performed the configuration and basic design of the target chamber. The method of fabrication and construction of the aluminum target chamber was devised by Pitt-Des Moines, Inc. (PDM). PDM also participated in the design of the chamber in areas such as the Target Chamber Realignment and Adjustment System, which would allow realignment of the sphere laser beams in the event of earth settlement or movement from a seismic event. During the fabrication of the target chamber the sphericity tolerances had to be addressed for the individual plates. Procedures were developed for forming, edge preparation and welding of individual plates. Construction plans were developed to allow the field construction of the target chamber to occur parallel to other NIF construction activities. This

  11. National Ignition Facility Target Chamber

    International Nuclear Information System (INIS)

    On June 11, 1999 the Department of Energy dedicated the single largest piece of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in Livermore, California. The ten (10) meter diameter aluminum target high vacuum chamber will serve as the working end of the largest laser in the world. The output of 192 laser beams will converge at the precise center of the chamber. The laser beams will enter the chamber in two by two arrays to illuminate 10 millimeter long gold cylinders called hohlraums enclosing 2 millimeter capsule containing deuterium, tritium and isotopes of hydrogen. The two isotopes will fuse, thereby creating temperatures and pressures resembling those found only inside stars and in detonated nuclear weapons, but on a minute scale. The NIF Project will serve as an essential facility to insure safety and reliability of our nation's nuclear arsenal as well as demonstrating inertial fusion's contribution to creating electrical power. The paper will discuss the requirements that had to be addressed during the design, fabrication and testing of the target chamber. A team from Sandia National Laboratories (SNL) and LLNL with input from industry performed the configuration and basic design of the target chamber. The method of fabrication and construction of the aluminum target chamber was devised by Pitt-Des Moines, Inc. (PDM). PDM also participated in the design of the chamber in areas such as the Target Chamber Realignment and Adjustment System, which would allow realignment of the sphere laser beams in the event of earth settlement or movement from a seismic event. During the fabrication of the target chamber the sphericity tolerances had to be addressed for the individual plates. Procedures were developed for forming, edge preparation and welding of individual plates. Construction plans were developed to allow the field construction of the target chamber to occur parallel to other NIF construction activities. This was

  12. Transport simulations of ohmic ignition experiment: IGNITEX

    International Nuclear Information System (INIS)

    The IGNITEX device, proposed by Rosenbluth et al., is a compact, super-high-field, high-current, copper-coil tokamak envisioned to reach ignition with ohmic (OH) heating alone. Several simulations of IGNITEX were made with a 0-D global model and with the 1-D PROCTR transport code. It is shown that OH ignition is a sensitive function of the assumptions about density profile, wall reflectivity of synchrotron radiation, impurity radiation, plasma edge conditions, and additional anomalous losses. In IGNITEX, OH ignition is accessible with nearly all scalings based on favorable OH confinement (such as neo-Alcator). Also, OH ignition appears to be accessible for most (not all) L-mode scalings (such as Kaye-Goldston), provided that the density profile is not too broad (parabolic or more peaked profiles are needed), Z/sub eff/ is not too large (≤2), and anomalous radiation and alpha losses and/or other enhanced transport losses (/eta//sub i/ modes, edge convective energy losses, etc.) are not present. In IGNITEX, because the figure-of-merit parameters (aB02/q* /approximately/ IB0, etc.) are large, ignition can be accessed (either with OH heating alone or with the aid of a small amount of auxiliary power) at relatively low beta, far from stability limits. Once the plasma is ignited, thermal runaway is prevented naturally by a combination of increased synchrotron radiation, burnout of the fuel in the plasma core and replacement by thermal alphas, and the reduction in the thermal plasma confinement assumed in L-mode-like scalings. 12 refs., 5 figs., 1 tab

  13. Experimental and Numerical Investigations of Thermal Ignition of a Phase Changing Energetic Material

    Directory of Open Access Journals (Sweden)

    Priyanka Shukla

    2016-04-01

    Full Text Available Fortuitous exposure to high temperatures initiates reaction in energetic materials and possibilities of such event are of great concern in terms of the safe and controlled usage of explosive devices. Experimental and numerical investigations on time to explosion and location of ignition of a phase changing polymer bonded explosive material (80 per cent RDX and 20 per cent binder, contained in a metallic confinement subjected to controlled temperature build-up on its surface, are presented. An experimental setup was developed in which the polymer bonded explosive material filled in a cylindrical confinement was provided with a precise control of surface heating rate. Temperature at various radial locations was monitored till ignition. A computational model for solving two dimensional unsteady heat transfer with phase change and heat generation due to multi-step chemical reaction was developed. This model was implemented using a custom field function in the framework of a finite volume method based standard commercial solver. Numerical study could simulate the transient heat conduction, the melting pattern of the explosive within the charge and also the thermal runaway. Computed values of temperature evolution at various radial locations and the time to ignition were closely agreeing with those measured in experiment. Results are helpful both in predicting the possibility of thermal ignition during accidents as well as for the design of safety systems.

  14. Ignition of a deuterium micro-detonation with a gigavolt super marx generator

    CERN Document Server

    Winterberg, Friedwardt

    2008-01-01

    The Centurion-Halite experiment demonstrated the feasibility of igniting a deuterium-tritium micro-explosion with an energy of not more than a few megajoule, and the Mike test, the feasibility of a pure deuterium explosion with an energy of more than 10^6 megajoule. In both cases the ignition energy was supplied by a fission bomb explosive. While an energy of a few megajoule, to be released in the time required of less than 10^-9 sec, can be supplied by lasers and intense particle beams, this is not enough to ignite a pure deuterium explosion. Because the deuterium-tritium reaction depends on the availability of lithium, the non-fusion ignition of a pure deuterium fusion reaction would be highly desirable. It is shown that this goal can conceivably be reached with a "Super Marx Generator", where a large number of "ordinary" Marx generators charge (magnetically insulated) fast high voltage capacitors of a second stage Marx generator, called a "Super Marx Generator", ultimately reaching gigavolt potentials with...

  15. National Ignition Facility project acquisition plan revision 1

    International Nuclear Information System (INIS)

    The purpose of this National Ignition Facility Acquisition Plan is to describe the overall procurement strategy planned for the National Ignition Facility M Project. It was prepared for the NIP Prood Office by the NIF Procurement Manager

  16. Highly Durable Catalysts for Ignition of Advanced Monopropellants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Monopropellants are readily ignited or decomposed over a bed of solid catalyst. A serious limitation of existing catalysts in the ignition of advanced...

  17. 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

  18. On the ignition of the ITER machine

    International Nuclear Information System (INIS)

    The present study on a simple model of the ITER machine (International Thermonuclear Experimental Reactor) shows that this machine, as presently designed, might not be able to reach either ignition or power breakeven. The large cost and the long time frame of the ITER program, on the other hand, do not allow for any doubt that the machine must reach its stated goal of ignition. Consequently, as long as these doubts persist, and cannot easily be dissipated, the ITER program should be put on hold, and fusion alternative concepts should be pursued. (author)

  19. Semiconductor bridge, SCB, ignition of energetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Bickes, R.W.; Grubelich, M.D.; Harris, S.M.; Merson, J.A.; Tarbell, W.W.

    1997-04-01

    Sandia National Laboratories` semiconductor bridge, SCB, is now being used for the ignition or initiation of a wide variety of exeoergic materials. Applications of this new technology arose because of a need at the system level to provide light weight, small volume and low energy explosive assemblies. Conventional bridgewire devices could not meet the stringent size, weight and energy requirements of our customers. We present an overview of SCB technology and the ignition characteristics for a number of energetic materials including primary and secondary explosives, pyrotechnics, thermites and intermetallics. We provide examples of systems designed to meet the modern requirements that sophisticated systems must satisfy in today`s market environments.

  20. Plasma igniter for internal combustion engine

    Science.gov (United States)

    Fitzgerald, D. J.; Breshears, R. R. (Inventor)

    1978-01-01

    An igniter for the air/fuel mixture used in the cylinders of an internal combustion engine is described. A conventional spark is used to initiate the discharge of a large amount of energy stored in a capacitor. A high current discharge of the energy in the capacitor switched on by a spark discharge produces a plasma and a magnetic field. The resultant combined electromagnetic current and magnetic field force accelerates the plasma deep into the combustion chamber thereby providing an improved ignition of the air/fuel mixture in the chamber.