Autoignition and Combustion of Fuels in Diesel Engines Under Low Ambient Temperatures PDF Download

Author: N. A. Henein
Publisher:
ISBN:
Category : Diesel fuels
Languages : en
Pages : 14

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 78

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This report includes the results of an investigation on the autoignition and combustion processes in diesel engines at low ambient temperatures. Experiments were conducted on three different single-cylinder direct-injection, four-stroke engines, using fuels of different cetane numbers and physical properties. Tests covered ambient temperatures ranging from 250C to -250C. The engines were soaked at least eight hours before a cold start test. The analysis indicated that the difficulty in starting diesel engines is caused by combustion instability at low temperatures. Combustion instability will cause the engine to misfire once before it fires again. This is referred to as 8-stroke-cycle operation. If it misfires twice, it is referred to as l2-stroke-cycle operation, and so on. This pattern was found to be reproducable. The engine may start on a l2-stroke-cycle operation at low temperatures, shift to an 8-stroke-cycle, and finally shifts to the regular 4-stroke-cycle. This pattern has been found not to be engine or fuel specific. A detailed thermodynamic and combustion analysis of the experimental data indicated that the cause for combustion instability is a combination of dynamic, physical and chemical kinetics factors. Recommendations are made to reduce combustion instability by using the electronic controls already available on engines.

Author: Mengyuan Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Because of increasingly stringent engine emissions and fuel economy standards, there is an urgent need for developing future diesel engines with higher efficiency and lower emissions. Therefore, low temperature combustion is currently being pursued to develop new types of advanced diesel engines. Since low temperature combustion is more sensitive to chemical kinetics, the understanding of the autoignition characteristics of diesel fuels under low-to-intermediate temperatures becomes important. In order to achieve the goal of higher efficiency and lower emissions diesel engines, both experimental and computational investigations of diesel fuels at low-to-intermediate temperatures need to be conducted, as the experimental autoignition results help develop a comprehensive understanding of diesel ignition and provide a validation database for model development, and a comprehensive chemical kinetic model of diesel is also imperative for accurate prediction of ignition and emissions characteristics of diesel engines. Because diesel fuels contain hundreds, even thousands of species, and the composition of diesel is too complex to model, it is also necessary to develop surrogate fuels, which are simpler mixtures that include fuel components representative of hydrocarbon classes found in diesel fuels, and can capture the essential chemical/physical properties and performance characteristics of the target diesel fuel to sufficient accuracy. Therefore, the work presented in the current dissertation aims to gain better understandings and fill in gaps in fundamental combustion data of diesel-surrogate components and surrogate fuel mixtures relevant to diesel fuels. Autoignition of trans-decalin at low-to-intermediate temperatures has been investigated first to get a better understanding of its autoignition characteristics, and the development of a detailed chemical kinetic model of diesel surrogates has been benefited from the results of trans-decalin. The agreements of the developed diesel surrogate model have been tested by comparing with the current autoignition results of diesel surrogates, and possible sources of discrepancies between experimental and simulated results have also been investigated. Based on that, binary blends of iso-cetane and tetralin are further chosen for autoignition investigation to help find out possible reasons causing those discrepancies and to further benefit the refinement and development of comprehensive diesel surrogate models.

Author:
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ISBN:
Category :
Languages : en
Pages : 1

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Methods of producing non-sooting, low flame temperature diesel combustion were investigated in an optically-accessible, quiescent constant-volume combustion vessel under mixing-controlled diesel combustion conditions. Combustion and soot processes of single, isolated fuel jets were studied after auto-ignition and transient premixed combustion and while the injector was fully-open (i.e. during the mixing-controlled phase of heat release for diesel combustion). The investigation showed that small injector tip orifices could be used to produce non-sooting and low flame temperature combustion simultaneously. The use of small orifices was shown to enable non-sooting and low flame temperature combustion in two different ways as summarized below. A more detailed description of the experimental methods and results is provided in Ref. [1-3]. First, using an injector tip with a 50 micron orifice and ambient oxygen concentrations as low as 10% (simulating the use of extensive EGR), a fuel jet was non-sooting at typical diesel ambient temperatures (1000 K). Second, using the same injector tip at a reduced ambient gas temperature (850 K), but with 21% oxygen, it was shown that non-sooting, mixing-controlled combustion occurred at the lift-off length in a fuel-air mixture with a cross-sectional average equivalence ratio of approximately 0.6-suggesting that the quasi-steady combustion was fuel-lean and thereby avoided the formation of a diffusion flame. The adiabatic flame temperature with reduced ambient oxygen concentration or fuel-lean combustion was approximately 2000 K, compared to typical diesel flame temperatures that exceed 2600 K. The 50 micron orifice results above were obtained using a No. 2 diesel fuel. However, using an oxygenated fuel (20 wt% oxygen), the investigation showed that the same low temperature combustion, either with reduced ambient oxygen concentration or fuel-lean combustion, was realized with a 100 micron orifice. Although these single, isolated jets do not have jet-jet interactions that would occur in realistic engines, the results are useful for understanding limiting-case behavior of single-jet mixing and combustion during an injection event. The non-sooting and low flame temperature mixing-controlled combustion realized using small orifice tips suggests that the use of small orifices offers the potential for a simultaneous soot and NOx reduction in an engine, much like diesel HCCI combustion. However, further research is needed to determine whether these methods could be successfully implemented in real engines.

Author: Harold Colby Gerrish
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 40

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Author: Gautam Kalghatgi
Publisher: Springer Nature
ISBN: 9811687358
Category : Technology & Engineering
Languages : en
Pages : 339

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This book focuses on gasoline compression ignition (GCI) which offers the prospect of engines with high efficiency and low exhaust emissions at a lower cost. A GCI engine is a compression ignition (CI) engine which is run on gasoline-like fuels (even on low-octane gasoline), making it significantly easier to control particulates and NOx but with high efficiency. The state of the art development to make GCI combustion feasible on practical vehicles is highlighted, e.g., on overcoming problems on cold start, high-pressure rise rates at high loads, transients, and HC and CO emissions. This book will be a useful guide to those in academia and industry.

Author: J. M. Kuchta
Publisher:
ISBN:
Category : Fuel
Languages : en
Pages : 30

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Author: Rakesh Kumar Maurya
Publisher: Springer
ISBN: 3319685082
Category : Technology & Engineering
Languages : en
Pages : 553

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This book deals with novel advanced engine combustion technologies having potential of high fuel conversion efficiency along with ultralow NOx and particulate matter (PM) emissions. It offers insight into advanced combustion modes for efficient utilization of gasoline like fuels. Fundamentals of various advanced low temperature combustion (LTC) systems such as HCCI, PCCI, PPC and RCCI engines and their fuel quality requirements are also discussed. Detailed performance, combustion and emissions characteristics of futuristic engine technologies such as PPC and RCCI employing conventional as well as alternative fuels are analyzed and discussed. Special emphasis is placed on soot particle number emission characterization, high load limiting constraints, and fuel effects on combustion characteristics in LTC engines. For closed loop combustion control of LTC engines, sensors, actuators and control strategies are also discussed. The book should prove useful to a broad audience, including graduate students, researchers, and professionals Offers novel technologies for improved and efficient utilization of gasoline like fuels; Deals with most advanced and futuristic engine combustion modes such as PPC and RCCI; Comprehensible presentation of the performance, combustion and emissions characteristics of low temperature combustion (LTC) engines; Deals with closed loop combustion control of advanced LTC engines; State-of-the-art technology book that concisely summarizes the recent advancements in LTC technology. .

Author:
Publisher:
ISBN:
Category : Diesel engines
Languages : en
Pages : 192

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Author: Ritu Gaur
Publisher: GRIN Verlag
ISBN: 3346061124
Category : Technology & Engineering
Languages : en
Pages : 22

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Research Paper (postgraduate) from the year 2019 in the subject Engineering - Chemical Engineering, , course: M.TECH, language: English, abstract: This work is an experimental study for the measurement of ignition delay characteristics of burning fuel sprays in cylindrical combustion chambers. It is carried out on hot air and high pressure. The objective of the study is to investigation the effect of hot air temperature and a well as high pressure on ignition delay of diesel fuel sprays. The effect of blending of n-Pentane with pure diesel was investigated. An experimental set up was design for this purpose with the emphasis on optical method for measurement of ignition delay at various pressures. The results presented here show that ignition delay of diesel fuel spray decreases with increase in the temperature and pressure of hot air. Results also show the effect of methyl group being more dominant at low ignition temperatures and that of alkyl group being more dominant at higher temperature. Blending of n-pentane with diesel fuel, increase its ignition delay at low ignition temperatures. However, as the concentration of blending fuel was increased beyond 30%, the ignition temperature increase. Ignition temperature for 40% pentane blends is much higher that the pure diesel.