Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains ix, 142 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 95-104).

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xiii, 85 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 82-84).

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xiv, 129 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 92-98).

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains xii, 105 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 96-100).

Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: To reduce exhaust gas emissions in diesel engines and for engine upgrade purposes the major parameters and equipment that should be looked at are boost pressure, intake charge temperature, combustion chamber design and fuel injection equipment. Boost pressure is governed by the turbo-charger; with high-efficiency variable geometry turbochargers, effective control is possible to increase airflow rate at all operating conditions of the engine. Efficient air-to-air inter-cooling results in the engine being filled with a cooler air charge that will influence engine durability and heat rejection to the cooling system. The main objective of the investigation is to look at the influence of boost pressure and intake charge temperature on diesel combustion to better understand the processes where boost pressure is increased and intake charge temperature reduced to increase the brake mean effective pressure of the engine and reduce emissions generation. By running an engine at different intake boost pressures and intake charge temperatures a 25-point matrix was formed at three different operating conditions. On completion of the engine testing, data processing and data evaluation, a number of important conclusions were made about the behaviour of the engine running under different conditions. This enabled the researcher to understand how boost pressure and intake charge temperature influence engine power output, fuel consumption, engine durability and exhaust gas emissions. The opinion is proved when, in most cases, the 75 test points were used to build multiple linear regression models to determine which engine parameters (dependent variables) have a significant effect on emissions generation and durability parameters. From the data it is evident that boost pressure has a positive influence on most engine parameters, as an increase in boost pressure results in an increase in air mass flow through the engine. An increase in air mass flow reduces combustion chamber gas temperature as the result of an increase in excess air ratio during combustion. A further result of the increase in excess air ratio is that less soot is formed during the first part of combustion and more soot and partly decomposed Hydrocarbon (HC) compounds are oxidised during the late combustion phase. Therefore, with an increase in boost pressure, Bosch smoke emissions reduce, but with a change in intake air temperature no difference in smoke concentration is seen except at the very low boost pressure and very high boost temperature test points where low air/fuel ratios exist and the slight increase in air-flow rate as a result of lower air inlet temperature has a big influence. Nitric Oxide (NO) emissions, on the other hand, are more dependent on intake air temperature than on boost pressure, which was proved in the multiple regressions modelling performed on the test data. The flame zone and the post-flame zone temperature play the dominant role in NO formation. As explained in the results discussion on NO formation, intake air temperature influences the ignition mixture temperature and the subsequent flame zone temperature. A lower intake air condition results in longer ignition delay and increases the initial rate of combustion. / AFRIKAANSE OPSOMMING: Die hoofparameters en toerusting wat in ag geneem moet word om uitlaatgasemissies in dieselenjins te verminder en om enjinkraguitset te verhoog, is inlaatdruk, inlaat lugtemperatuur, verbrandingskamerontwerp en brandstofinspuittoerusting. Inlaatdruk word beheer deur die turb-aanjaer. Met hoë effektiwiteit, veranderlike geometrie turboaanjaging, is effektiewe beheer moontlik om lugvloei-tempo deur die enjin te verhoog onder alle enjinwerkstoestande. Effektiewe lug-tot-lug tussenverkoeling laat die enjin met koeler inlaatlug vul, wat 'n uitwerking het op enjinlewensduur en hitte-verlies na die verkoelingsstelsel. Die hoofdoel van die navorsing is om die invloed van inlaatdruk en inlaat lugtemperatuur op dieselverbranding te ondersoek. Sodoende kry die navorser 'n beter begrip omtrent die prosesse waar inlaatdruk verhoog en inlaat lugtemperatuur verlaag word, om rem-gemiddelde effektiewe druk van die enjin te verhoog en uitlaatgas emissies te verlaag. 'n 25-punt matriks is opgestel deur die enjin by verskillende inlaatdrukke en inlaat lugtemperture te opereer, en by drie verskillende wringkragwerkstoestande. 'n Aantal belangrike gevolgtrekkings is gemaak omtrent enjinwerking onder verskillende werkstoestande na voltooiing van die enjintoetse, dataverwerking en data-evaluering. Sodoende het die navorser bepaal hoe inlaatdruk en inlaat lugtemperatuur kraglewering, brandstofverbruik, enjinlewensduur en uitlaatgasemissies beïnvloed. Om bogenoemde begrippe verder te ondersteun is 'n meervoudige, lineëre regressiemodel opgestel om te bepaal watter enjinparameters (afhanklike veranderlikes) 'n wesenlike effek op emissiegenerasie en lewensduur het. Van die data word afgelei dat inlaatdruk 'n positiewe effek op die meeste enjinparameters het, omdat hoër inlaatdruk die lugvloeitempo deur die enjin verhoog. Hoër lugmassavloei verminder verbrandingsgastemperatuur as gevolg van 'n hoër oortollige lugverhouding tydens verbranding. 'n Verdere gevolg van 'n hoër oortollige lugverhouding is dat minder roet gevorm word gedurende die eerste verbrandingsfase en meer roet en gedeeltelik verbrande koolwaterstofverbindings oksideer gedurende die finale verbrandingsfase. Dus, met 'n hoër inlaatdruk word Bosch rookemmissies verlaag. Geen wesenlike verandering in rookkonsentrasies word egter gesien met 'n verandering in inlaatlugtemperatuur nie, behalwe by baie lae inlaatdruk- en hoë inlaat lugtemperatuur-toetskondisies waar lae lug/brandstofverhoudings bestaan en 'n klein toename in lugmassavloei as gevolg van laer inlaat lugtempertuur'n groot invloed het. Stikstofmonoksied (NO) emissies is meer afhanklik van inlaat lugtemperatuur as inlaatdruk. Dit is bewys in die meervoudige regressiemodel. Die vlamsone- en die navlamsone- temperatuur speel 'n groot rol in NO vorming. Inlaat lugtemperatuur beïnvloed die temperatuur van die onstekingsmengsel en die daaropvolgende vlamsonetemperatuur. 'n Laer inlaat lugtemperatuur veroorsaak 'n langer onstekingsvertraging en verhoog die aanvanklike verbrandingstempo.

published_or_final_version / abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy

An existing encoder system was analyzed to determine why the system had failed. This encoder system was found to have slipped off the crankshaft, resulting in the need for a new encoder mount system. A new encoder mount was designed and installed on a Detroit Diesel 3-53 engine. The encoder mount was designed to ensure positive contact with the crankshaft while not allowing the mechanism to have the same type of failure that was determined. During the validation of the encoder, the push rod connected to the fuel injector rocker arm failed, preventing further validation of the system. The failure of the push rods is described.

The introduction of alternative fuels such as natural gas is likely to occur at an increasing rate. The dual-fuel concept allows these low cetane number fuels to be used in compression-ignition (CI, diesel) type engines. Most CI engine conversions have pre-mixed the alternative fuel with air in the intake manifold while retaining diesel injection into the cylinder for ignition. The advantage is that it is simple for practical adaptation; the disadvantage is that good substitution levels are only obtained at midload. A better solution is to inject both the alternative and diesel fuels directly into the cylinder. Here, the fuel in the end-zone is limited and the diesel, injected before the alternative, has only a conventional ignition delay. This improves the high-end performance. Modern, very high pressure diesel injectors have good turndown characteristics as well as better controllability. This improves low-end performance and hence offers an ideal platform for a dual-fuel system. Several systems already exist, mainly for large marine engines but also a few for smaller, truck-sized engines. For the latter, the key is to produce a combined injector to handle both fuels which has the smallest diameter possible so that installation is readily achieved. There exists the potential for much improvement. A combined gas/diesel injection system based on small, high pressure common-rail injectors has been tested for fluid characteristics. Spray properties have been examined experimentally in a test rig and modelled using CFD. The CFD package Fluent was used to model the direct-injection of natural gas and diesel oil simultaneously into an engine. These models were initially calibrated using high-speed photographic visualisation of the jets. Both shadowgraph and schlieren techniques were employed to identify the gas jet itself as well as mixing regions within the flow. Different orientations and staging of the jets with respect to each other were simulated. Salient features of the two fuel jets were studied to optimise the design of a dual-fuel injector for CI engines. Analysis of the fuel-air mixture strength during the injection allowed the ignition delay to be estimated and thus the best staging of the jets to be determined.

Thesis (M. P. A.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xiv, 160 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 120-122).