Diesel combustion

Diesel Combustion and Emissions," Proceedings P-86. Society of Automotive Engineers, Warrendale, PA, 1980. 

Conceptual model of conventional Cl combustion characterized by a sequence of processes occurring in a fully developed reacting jet. (From Dec, A Conceptual Model of DI Diesel Combustion Based on Laser Sheet Imaging, SAE, 970873,1997. With permission.)... 

Miles, R, The Influence of Swirl on HSDl Diesel Combustion at Moderate Speed and Load, SAE, 2000-01-1829,2000. 

Miles, P. C., In-cylinder Flow and Mixing Processes in Low-Temperature Diesel Combustion Systems, Proceedings of the THIESEL 2006 Conference Thermo- and Fluid-Dynamic Processes in Diesel Engines, Valencia, Spain, September 12-15, 2006. 

In contrast to past environmental problems associated with fluorocarbon refrigerants, the exceptional properties of fluorine in polymers have great environmental value. Some fluoropolymers are enabling green technologies such as hydrogen fuel cells for automobiles and oxygen-selective membranes for cleaner diesel combustion. 

Figure 2. Schematic representation of stages of Diesel combustion in relation to indicator card...

Whilst NOx emissions from petrol vehicles can be controlled by catalytic reduction, this is not very effective under the oxygen-rich conditions of diesel combustion. A diesel oxidation catalyst (DOC) is similar to a TWC in terms of structure and configuration but is only capable of oxidation. As the exhaust gases pass through the catalyst CO, unbumt HC and volatile PM are oxidised. The conversion efficiency is a function of cell size, reactive surface, catalyst load and catalyst temperature, although emissions of CO and HC are typically reduced with an efficiency of more that 95%. 

Diesels tend to smoke, especially under heavy load. This is not due to any inherent inefficiency of Diesels. On the contrary, Diesels are extremely efficient. The smoke is the result of the nature of Diesel combustion and the heavier fuels which Diesels use compared to gasoline engines. 

Combustion processes also generate many other contaminants. For example, diesel combustion produces more than 40 components including gases, vapors, and fine particles, many of them hazardous. 

It is apparent from the above data that Thermofuel diesel produces significantly less particulates (smoke) at all engine loadings than conventional diesel. This is environmentally significant, as the particulates formed from diesel combustion contain polycyclic aromatic hydrocarbons (PAH) which have carcinogenic potential. The hotter burning characteristic of the Thermofuel relative to conventional diesel is likely to be responsible for the better burn-out of particulates [21]. 

From Table IV can be observed that the emissions from bio-fuel oil combustion are slightly higher compared to the emissions from diesel combustion. 

CEB will be used for coal and waste combustion, and not primarily for heavy fuel oil. However, the projected large-scale test 7 MW, facility can only use heavy fuel oil. Therefore, this oil was used to test it on a small scale. A small flame tunnel with separate air and liquid fuel injectors was constructed to demonstrate the potential of CEB to recover SO2. Figure 10 shows a photograph of the set-up, with the control panel at the right hand, and the flame tunnel in the middle. The three injection ports for CEB material are visible at the front side. Through the opening in the middle (the nozzle has been removed), the flame from diesel combustion is clearly visible. In all experiments, CEB is sprayed perpendicular to the fuel stream. A portable Mass Spectrometer has been purchased to analyse the exit gases from the flame tunnel experiments on SO2. 

Particulates are another source of respiratory irritation when inhaled. In urban environments, diesel exhaust particles and fly ash residue from power plant oil combustion are the main contributors of respirable particulates of less than 10 pm diameter (PM 10). These contain mixtures of lipo-philes and hydrophiles including various metals, acid salts, aliphatic hydrocarbons, PAHs, quinones, nitroaromatic hydrocarbons, andaldehydes. 151 Diesel combustion particulates contain large surface areas that can adsorb large quantities of organic compounds and deliver these to respiratory tract tissue. Other inhaled particulates can adhere to lung surfaces and adsorb and bond other vapors that are inhaled, thereby increasing their toxicities. PM2.5 particulates (those with diameters of less than 2.5 pm) that reach the lower respiratory tract as far as the alveoli are more toxic than PM 10 particulates of the same composition. 16 ... 

The need to have an environmentally friendly fuel available for diesel combustion engines. 

Soot dispersion Soot particles formed during the diesel combustion process can cause three-body wear in the engine and must be dispersed to prevent this happening. Soot is suspended in the oil by dispersants, which minimises the effect of soot on wear. 

H. Yokota, Y. Kudo, H. Nakajima, T. Kakegawa, T. Suzuki "A New Concept for Low Emission Diesel Combustion." SAE Paper 970891. 

K. Nakagome, N. Shimazaki, K. Niimura, S. Kobayashi "Combustion and Emission Characteristics of Premixed Lean Diesel Combustion Engines. SAE Paper 970898. 

Song, J., Zello, V., Boehman, A.L. and Waller, F.J. (2004) Comparison of the impact of intake oxygen enrichment and fuel oxygenation on diesel combustion and emissions. Energy Fuels, 18, 1282-1290. 

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