Reduction of Spark-ignition Engine Hydrocarbon Emissions and the Associated Local Ozone Production Through Variable Exhaust Valve Timing PDF Download
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Author: Stani V. Bohac
Publisher:
ISBN:
Category :
Languages : en
Pages : 464
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Author: Stani V. Bohac
Publisher:
ISBN:
Category :
Languages : en
Pages : 464
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Author: Manbae Han
Publisher:
ISBN:
Category :
Languages : en
Pages : 428
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Author: Kevin R. Lang
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
(Cont.) By timing split injection such that the second injection event hits the overlap back flow, a small mixture preparation and emissions benefit was achieved. Earlier IVO results in a longer back flow period, however the impact on mixture preparation is small. The observed reduction in HC emissions resulted from a higher residual gas fraction due to early IVO, which yielded later combustion phasing, which in turn yielded increased post-flame oxidation. Under steady-state cold coolant conditions, operation of a 4-cylinder engine with three cylinders running rich and the fourth used to pump air into the exhaust manifold resulted in near total oxidation of CO and HC at sufficiently retarded spark timing. Exhaust gas temperatures and enthalpy flow rates were significantly higher than for the conventional engine configuration at fast idle. Using this strategy to perform real cold starts proved challenging without the additional hardware needed for sufficient control over air flow to the engine.
Author: American Society of Mechanical Engineers. Internal Combustion Engine Division. Technical Conference
Publisher:
ISBN:
Category : Internal combustion engines
Languages : en
Pages : 744
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Author: Kevin David Cedrone
Publisher:
ISBN:
Category :
Languages : en
Pages : 191
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Book Description
Gasoline consumption and pollutant emissions from transportation are costly and have serious, demonstrated environmental and health impacts. Downsized, turbocharged direct-injection spark ignition (DISI) gasoline engines consume less fuel and achieve superior performance compared with conventional port fuel injected spark ignition (PFI-SI) engines. Although more efficient, turbocharged DISI engines have new emissions challenges during cold start. DISI fuel injection delivers more liquid fuel into the combustion chamber, increasing the emissions of unburned hydrocarbons. The turbocharger slows down activation (warm-up) of the catalytic exhaust after-treatment system. The objective of this research is to find a control strategy that: 1. Accelerates warm-up of the catalyst, and 2. Maintains low emissions of unburned hydrocarbons (UBHCs) during the catalyst warm-up process. This research includes a broad experimental survey of engine behaviour and emission response for a modern turbocharged DISI engine. The study focuses on the idle period during cold-start for which DISI engine emissions are worst. Engine experiments and simulations show that late and slow combustion lead to high exhaust gas temperatures and mass flow rate for fast warm-up. However, late and slow combustion increase the risk of partial-burn misfire. At the misfire limit for each parameter, the following conclusions are drawn: 1. Late ignition timing is the most effective way to increase exhaust enthalpy flow rate for fast catalyst warm-up. 2. By creating a favourable spatial fuel-air mixture stratification, split fuel injection can simultaneously retard and stabilize combustion to improve emissions and prevent partial-burn misfire. 3. Excessive trapped residuals from long valve overlap limit the potential for valve timing to reduce cold-start emissions. 4. Despite their more challenging evaporation characteristics, fuel blends with high ethanol content showed reasonable emissions behaviour and greater tolerance to late combustion than neat gasoline. 5. Higher exhaust back-pressure leads to high exhaust temperature during the exhaust stroke, leading to significantly more post-flame oxidation. 6. Post-flame oxidation in the combustion chamber and exhaust system play a critical role in decreasing the quantity of catalyst-in emissions due to hydrocarbons that escape primary (flame) combustion. A cold start strategy combining late ignition, 15% excess air, and high exhaust backpressure yielded the lowest cumulative hydrocarbon emissions during cold start.
Author: Bruno P. Vanzieleghem
Publisher:
ISBN:
Category :
Languages : en
Pages : 310
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Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 768
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Author: Ronald S. Tharp
Publisher:
ISBN:
Category :
Languages : en
Pages : 89
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Book Description
In order to better understand the effects on hydrocarbon emissions of loading, engine temperature, fuel type, and injection timing, a series of experiments was performed. The effect of loading was observed by running the engine at a higher temperature and more open throttle than would typically be observed at fast idle or low load driving. The effects of coolant temperature, the charge motion control valve, spark timing and rail pressure were tested through holding all other variables constant and sweeping through different injection timing to observe the effect on emissions and power output. A new fuel system was designed to allow for the quick testing of different ethanol blends. The system allowed for comparison testing of an 85% ethanol blend to UTG 91 as a function of coolant temperature and injection timing. Measurement of cylinder pressure and hydrocarbon emissions near the exhaust valve allowed for a better understanding of engine operation and the effect of using high ethanol content fuels. Initial testing was also done on 15% and 40% ethanol blends. The results revealed that engine emissions decrease as a function of reduced loading and higher engine temperatures. Sweeps of injection timings for all fuels demonstrated high hydrocarbon emissions for earlier injection timings which fell as injection timing was retarded. A secondary peak was observed in hydrocarbon emissions for an injection timing of approximately 150 CAD aTDC intake. Analysis of rate of fuel injection vs. indicated power revealed a steady decrease in indicated efficiency as injection timing was retarded up to 120 CAD aTDC Intake and then a slow rise in efficiency as the timing was further retarded. The exact causes of the decrease in engine efficiency are unknown; however, possible explanations involve increased heat transfer from the cylinder and piston, fuel loss, and inefficient combustion due to impingement on cold surfaces.
Author: Krzysztof Jan Siczek
Publisher: Butterworth-Heinemann
ISBN: 0081009739
Category : Technology & Engineering
Languages : en
Pages : 299
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Book Description
Tribological Processes in Valvetrain Systems with Lightweight Valves: New Research and Modelling provides readers with the latest methodologies to reduce friction and wear in valvetrain systems—a severe problem for designers and manufacturers. The solution is achieved by identifying the tribological processes and phenomena in the friction nodes of lightweight valves made of titanium alloys and ceramics, both cam and camless driven. The book provides a set of structured information on the current tribological problems in modern internal combustion engines—from an introduction to the valvetrain operation to the processes that produce wear in the components of the valvetrain. A valuable resource for teachers and students of mechanical or automotive engineering, as well as automotive manufacturers, automotive designers, and tuning engineers. - Shows the tribological problems occurring in the guide-light valve-seat insert - Combines numerical and experimental solutions of wear and friction processes in valvetrain systems - Discusses various types of cam and camless drives the valves used in valve trains of internal combustion engines—both SI and CI - Examines the materials used, protective layers and geometric parameters of lightweight valves, as well as mating guides and seat inserts
Author: Mina Abaskharon
Publisher:
ISBN: 9783668249653
Category :
Languages : en
Pages : 16
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Book Description
Scientific Essay from the year 2015 in the subject Engineering - Automotive Engineering, language: English, abstract: In the present work a comparative assessment has been made for the exhaust emissions of a spark ignition engine fueled with gasoline and CNG. The engine under test was operated separately by gasoline or CNG using a conversion switch. The produced hydrocarbon (HC), carbon monoxide (CO) and carbon dioxide (CO 2) of both fuels were measured at coolant temperature of 80 C, 90 C and 100 C. Tests have been conducted at full and half load operating conditions with a speed range from 1000:5000 rpm. The results showed that reducing the coolant temperature from 100 C to 80 C increased the produced hydrocarbon and carbon dioxide and reduced the carbon monoxide for both fuels at full and half load conditions. Furthermore, the CNG produced less HC, CO and CO 2 than the gasoline at full and half load operating conditions."
