Operating diesel engines

Howe, W. A., Factors Affecting Diesel Smoke in Highway Operation/ Diesel Engine... 

Another approach is to cool and filter the gas and utilize it as an alternative fuel for internal combustion engines. Skov and Papworth, (2), described the operation of trucks, buses, and agricultural equipment in Europe with gas produced using portable wood fueled gasifiers. Gasifiers can also be used to operate diesel engines as described in (6) and (9). 

By causing operating diesel engines to shut down... 

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). 

The diesel engine operates, inherently by its concept, at variable fuel-air ratio. One easily sees that it is not possible to attain the stoichiometric ratio because the fuel never diffuses in an ideal manner into the air for an average equivalence ratio of 1.00, the combustion chamber will contain zones that are too rich leading to incomplete combustion accompanied by smoke and soot formation. Finally, at full load, the overall equivalence ratio... 

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... 

Finally, sulfur has a negative effect on the performance of the catalyst itself. One sees for example in Figure 5.23 that the initiation temperature increases with the sulfur level in the diesel fuel, even between 0.01% and 0.05%. Yet, in the diesel engine, characterized by relatively low exhaust temperatures, the operation of the catalyst is a determining factor. One can thus predict an ultimate diesel fuel desulfurization to levels lower than 0.05%. 

The first methanol bus in the world was placed in revenue service in Auckland, New Zealand in June 1981. It was a Mercedes O 305 city bus using the M 407 hGO methanol engine. This vehicle operated in revenue service for several years with mixed results. Fuel economy on an equivalent energy basis ranged from 6 to 17% mote than diesel fuel economy. Power and torque matched the diesel engine and drivers could not detect a difference. ReHabiUty and durabihty of components was a problem. Additional demonstrations took place in Berlin, Germany and in Pretoria, South Africa, both in 1982. 

A. Lawson, A. J. Last, A. S. Desphande, and E. W. Simmons, "Heavy-Duty Tmck Diesel Engine Operation on Unstabihzed Methanol/Diesel Euel Emulsion," SAE Paper 810346, (SP-480) Int. Congress and Expo (Detroit, Mich., Peb. 23—27,1981) Society of Automotive Engineers, Warrendale, Pa. 

Heavy-duty diesel engines can also be modified to operate on neat methanol. Emissions of NO and particulates are generaHy lower than the original engine. These types of engines have typicaHy been used in urban buses to help reduce ambient poHution levels. 

Oil Companies Materials Association, Recommendations for the Protection of Diesel Engines Operating in Hazardous Areas, Wiley, Chichester, UK, 1977. 

The diesel engine operates with a much higher compression ratio (CR) than does a gasoline engine, and therefore is manufactured with structurally... 

Diesel engines, however, operate on an unrestricted air flow at all speeds and loads to provide the cylinders with an excess air charge. This results in a very lean air/fuel ratio of approximately 90 1 to 100 1 or higher at an idle speed. At the engine s rated speed (full load maximum power output) the air/fucl ratio will drop to 20 1 to 25 1 but still provide an excess air factor here of 10 to 20 percent. This excess air supply lowers the average specific heat of the cylinder gases, which in turn increases the indicated work obtained... 

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