Spark-ignited engines

Dispersingagents, such as polyethylene polyamide succinimides or methacrylate-type copolymers, are added to motor oils to disperse low-temperature sludge formed in spark-ignition engines. 

Power output is controlled, not by adjusting the quantity of fuel/air mixture as in the case of induced spark ignition engines, but in changing the flow of diesel fuel introduced in a fixed volume of air. The work required to aspirate the air is therefore considerably reduced which contributes still more to improve the efficiency at low loads. 

A. A. Quader, Why Intake Charge Dilution Decreases Nitric Oxide Emissionsfrom Spark Ignited Engines, SAE 710009, Society of Automotive Engineers, Warrendale, Pa., 1971. 

Figure 16-2. Idealized P-V diagram for a 4-cycle, spark-ignited engine.

Inlet port injection is used with liquid fuel, spark ignition engines only. Fuel is injected into the inlet port and mixed with the inlet iii The injection process may be either timed or continuous. 

Unlike carbon dioxide and water that are the inevitable by products of complete combustion of hydrocarbons, species such as carbon monoxide, ethene, toluene, and formaldehyde can be emitted because combustion has been interrupted before completion. Many factors lead to emissions from incomplete combustion. Emitted unburned hydrocarbons and carbon monoxide are regulated pollutants that must be eliminated. In automobiles with spark ignited engines, these emissions are almost entirely removed by the catalytic converter. 

Because many practical flames are turbulent (spark ignited engine flames, nil field flares), an understanding of the interaction between the complex fluid dynamics of turbulence and the combustion processes is necessary to develop predictive computer models. Once these predictive models are developed, they arc repeatedly compared with measurements of species, temperatures, and flow in actual flames for iterative refinement. If the model is deficient, it is changed and again compared with experiment. The process is repeated until a satisfactory predictive model is obtained. 

Carbon monoxide (CO) is a colurless, odorless, and tasteless gas. Inhalation of as little as 0.3 percent by volume can cause death within thirty minutes. The exhaust gas from spark ignition engines at an idle speed has a high CO content. For this reason NEVER allow an engine to run in an enclosed space such as a closed garage. 

Because combustion is normally initiated by an electric spark, the gasoline engine is also frequently known as a spark-ignition engine. 

Power unit manufacture also produce diesel engines that can be converted to operate on a dual fuel carburation of about 10% diesel and natural gas. Such conversions are more difficult than converting spark-ignition engines to various gas fuels. 

The use of propane as a motor vehicle fuel has been highly developed in some countries, particularly in the USA, Holland and Italy. It is, of course, an entirely lead-free fuel. Very high efficiencies can be obtained using a gaseous fuel in spark-ignition engines since intimate mixing of the fuel and air is much more easily achieved than with a liquid fuel. This results in a much cleaner exhaust, with considerable reductions in CO and hydrocarbons. 

Vehicle fleet owners often have their cars and/or vans converted to run on LPG and have an on-site bulk storage vessel installed complete with a dispensing pump. This is an attractive economic proposition for taxis, ambulances, local authority fleets, etc. Virtually any spark-ignition engine can be converted to run on LPG. It can therefore be considered for any engine-driven machinery. 

Daneshyar, H. D. and Hill, F. G., The structure of small-scale turbulence and its effect on combustion in spark ignition engines. Progress in Energy and Combustion Science, 13,47-73,1987. 

Tabaczynski, R. Trinker, F. H., and Shannon, B. A. S., Further refinement and validation of a turbulent flame propagation model for spark-ignition engines. Combustion and Flame, 39, 111-121, 1980. 

Ferguson, G.R. and Keck, J.G., On laminar flame quenching and its application to spark ignition engines, Combust. Flame, 28 197,1977. 

In fact, the clearly posed problem of the final state of an unstable laminar flame is a limiting case of turbulent flame for vanishing initial turbulence of the oncoming flow, but the general case, for any initial velocity fluctuations, is clearly of great interest in practical devices such as spark-ignited engines, turbojet, or gas turbine combustion chambers. 

Boudier, R, S. Henriot, T. Roinsot, T. Baritaud, A model for turbulent flame ignition and propagation in spark ignition engines. Proc. Combust. Inst., 1992. 24 503-510. 

Richard, S., Colin, O., Vermorel, O., Benkenida, A., Angelberger, C., and Veynante, D., Towards large eddy simulation of combustion in spark ignition engines. Proc. Comb. Inst., 2007. 31,3059-3066. 

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