Diesel engine emissions, combustion

For similar motivations, there are limited incentives to develop an alternative SCR process for stationary sources based on methane (CH4-SCR) or other HCs, or based on NTP technologies, if not for specific, better applications. The situation is instead quite different for mobile sources, and in particular for diesel engine emissions. The catalytic removal of NO under lean conditions, e.g. when 02 during the combustion is in excess with respect to the stoichiometric one (diesel and lean-burn engines, natural gas or LPG-powered engines), is still a relevant target in catalysis research and an open problem to meet future exhaust emission regulations. 

Barry, E. G., L. J. McCabe, D. H. Gerke, and J. M. Perez. 1985. Heavy-duty diesel engine/fuels combustion performance and emissions A cooperative research program. Report No. 852078. Warrendale, Pa. Society of Automotive Engineers. 

Lapuerta M, Armas O, Rodriguez-Femandez J (2008) Effect of biodiesel fuels on diesel engine emissions. Prog Energy Combust Sci 34 198-223... 

Utility systems as sources of waste. The principal sources of utility waste are associated with hot utilities (including cogeneration systems) and cold utilities. Furnaces, steam boilers, gas turbines, and diesel engines all produce waste from products of combustion. The principal problem here is the emission of carbon dioxide, oxides of sulfur and nitrogen, and particulates (metal oxides, unbumt... 

With respect to fuels utilized as heating fuels for industrial furnaces, or as motor fuels for large diesel engines such as those in ships or power generation sets, the characteristics of primary importance are viscosity, sulfur content and the content of extremely heavy materials (asphaltenes) whose combustion can cause high emissions of particulates which are incompatible with antipollution legislation. 

In a general manner, diesel engines, jet engines, and domestic or industrial burners operate with lean mixtures and their performance is relatively insensitive to the equivalence ratio. On the other hand, gasoline engines require a fuel-air ratio close to the stoichiometric. Indeed, a too-rich mixture leads to an excessive exhaust pollution from CO emissions and unburned hydrocarbons whereas a too-lean mixture produces unstable combustion (reduced driveability and misfiring). 

Improving the cetane number by additives results in better engine behavior, as would be predicted by the combustion mechanisms in the diesel engine (noise reduction, better operating characteristics, particularly when cold). Nevertheless, concerning certain items such as pollution emissions, it may be better to obtain a higher cetane number rather by modification of the... 

For land-based gas turbines, the overall plant output, efficiency, emissions, and reliability are the important variables. In a gas turbine, the processes of compression, combustion, and expansion do not occur in a single component, as they do in a diesel engine. They occur in components that can be developed separately. Therefore, other technologies and components can be added as needed to the basic components, or entirely new components can be substituted. 

Typical re-entrant piston-bowl design for a small, high-speed direct-injection Cl engine. (From Kook, S., Bae, C., Miles, P.C., Choi, D., Bergin, M., and Reitz, R.D., The Effect of Swirl Ratio and Fuel Injection Parameters on CO emission and Fuel Conversion Efficiency for High-Dilution, Low-Temperature Combustion in an Automotive Diesel Engine, SAE, 2006-01-019 2006. With permission.)... 

Daimler-Benz has accumulated data on NECAR III emissions with a dynamometer programmed for a mix of urban and suburban driving. The results were promising since there were zero emissions for nitrogen oxide and carbon monoxide, and extremely low hydrocarbon emissions of only. 0005 per gram per mile. NECAR III did produce significant quantities of carbon dioxide similar to the emissions of a direct-injection diesel engine where the fuel is injected directly into the combustion chamber. Direct-injection produces less combustion residue and unburned fuel. 

For soybean-based biodiesel at this concentration, the estimated emission impacts for percent change in emissions of NO,, particular matter (PM), HC, and CO were +20%, -10.1%, -21.1%, and -11.0%, respectively (EPA, 2002). The use of blends of biodiesel and diesel oil are preferred in engines in order to avoid some problems related to the decrease of power and torque, and to the increase of NO, emissions (a contributing factor in the localized formation of smog and ozone) that occurs with an increase in the content of pure biodiesel in a blend. Emissions of all pollutants except NO appear to decrease when biodiesel is used. The use of biodiesel in a conventional diesel engine dramatically reduces the emissions of unbumed hydrocarbons, carbon dioxide, carbon monoxide, sulfates, polycyclic aromatic hydrocarbons, nitrated polycyclic aromatic hydrocarbons, ozone-forming hydrocarbons, and particulate matter. The net contribution of carbon dioxide from biomass combustion is small. 

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