Exhaust, automotive combustion engine

Carbon monoxide emissions from internal combustion engines are commonly plotted as functions of air/fuel ratio or fuel/air ratio. Fuel/air ratio is merely the reciprocal of air/fuel ratio.34 It has generally been accepted by the automotive experts that the CO level of Diesel exhaust is related chiefly to these ratios and not to other factors, such as rpm. 

A major engineering textbook from 1998, which should contain just about everything one needs to know about Diesel emissions, is entitled Handbook of Air Pollution from Internal Combustion Engines with the subtitle Pollutant Formation and Control. The book is co-authored by a dozen of the world s leading experts on automotive emissions. It should be an excellent source of information on precisely how one might kill people with Diesel exhaust. But in the entire 550 page book, which is rather typical of all other hooks one can find on this subject, there was only one sentence relevant to our subject.65... 

Oxygen sensors are the most widely used solid electrolyte-based sensors [393-395], because the control of oxygen concentrations is critical to controlling the combustion process. For automotive applications, exhaust gas oxygen (EGO) sensors provide critical information for controlling the air-to-fuel ratio for internal combustion engines [396, 397]. Tlte use of an optimal air-to-fuel ratio leads to increased efficiency and reduced emissions. 

To understand the production and control of automotive hydrocarbon exhaust products, it is helpful to understand the basic principles of the internal combustion engine. As shown in Figure 16.9, the four steps involved in one complete cycle of the four-cycle engine used in most vehicles are the following ... 

Three way catalysts are generally used today for controlling exhaust emissions from automotive Internal combustion engines. Cerium oxide is widely employed as an additive in three way catalysts because of its abilities to store oxygen and to improve dispersion of platinum.[1] One drawback of the three way catalyst is that it tends to give rise to thermal deactivation caused by crystallization of cerium oxide, sintering of platinum and... 

Note that for certain older engines, small quantities lead deposits from combustion could have a positive effect as a solid lubricant and prevent exhaust valve recession. For these motors which still represented in 1993 from 20 to 30% of the French automotive fleet, the use of unleaded fuel is not possible. 

J. W. Butier and co-workers, FastKesponse Zirconia Sensor-Fased Instrument for Measurement of the Air (Fuel Katio of Combustion Exhaust, SAE 840061, Society of Automotive Engineers, Warrendale, Pa., 1984. 

This is an extremely important reaction to which we wiU refer throughout this book. It is responsible for all NO, formation in the atmosphere (the brown color of the air over large cities) as well as nitric acid and acid rain. This reaction only occurs in high-temperature combustion processes and in lightning bolts, and it occurs in automobile engines by free-radical chain reaction steps, which will be the subject of Chapter 10. It is removed from the automobile exhaust in the automotive catalytic converter, which wiU be considered in Chapter 7. 

Another important application of heterogeneous catalysts is in automobile catalytic converters. Despite much work on engine design and fuel composition, automotive exhaust emissions contain air pollutants such as unburned hydrocarbons (CxHy), carbon monoxide, and nitric oxide. Carbon monoxide results from incomplete combustion of hydrocarbon fuels, and nitric oxide is produced when atmospheric nitrogen and oxygen combine at the high temperatures present in an... 

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