Automobiles environment

Westerholm, R. N., T. A. Alsberg, A. B. Frommelin, and M. E. Strandell, Effect of Fuel Polycyclic Aromatic Hydrocarbon Content on the Emissions of Polycyclic Aromatic Hydrocarbons and Other Mutagenic Substances from a Gasoline-Fueled Automobile, Environ. Sci. Technol, 22, 925-930 (1988). 

Lawryk, N. J., and C. P. Weisel, Concentrations of Volatile Organic Compounds in the Passenger Compartments of Automobiles, Environ. Sci. Technol., 30, 810-816 (1996). 

Lloyd, S. and Lave, L. (2003) Life cycle economic and environmental implications of using nanocomposites in automobiles. Environ. Sci. Technol., 37, 3458-3466. 

Lawryk NJ, Weisel CP. 1996. Concentrations of volatile organic compounds in the passenger compartments of automobiles. Environ Sci Technol 30 810-816. 

For sensors in the automobile environment, mechanical shock load, humidity, elevated temperature, and temperature shock are the main causes of failure. Table 5.9.1 gives an overview of typical failure issues that are most common in microsensors and which need to be considered in reliability studies. 

DaimlerChrysler Corporation Winking with Recyclo s to Increase Recovery, Reuse of Plastics from Automobiles, Environment News Service, Sept. 19,2000. 

The severity of external automotive corrosion varies considerably throughout the world, due to differences in the chemistry of the environment [/-3]. The severest corrosion environments are in the snowbelt areas where deicing salts are used and along coastal areas where warm, humid, salt atmospheres exist. During the 20th century, the chemistry of the environment changed drastically. As a result of those changes, the corrosivity of the automobile environment increased. 

Increased corrosion rates have been measured for steel in the presence of both SO2 and NOx. This synergistic effect may be important in the automobile environment because automobile emissions contain NOx. 

Electrical and electronic systems are extremely susceptible to corrosion by the aggressive automobile environment [29-3i], Pitting, crevice and galvanic corrosion, and corrosion product creep are all important mechanisms, and in many cases these mechanisms are accelerated by leakage currents, which impose a potential bias on the materials. Fretting and coatings failure are also failure mechanisms. 

Electrochemical Microsensors. The most successful chemical microsensor in use as of the mid-1990s is the oxygen sensor found in the exhaust system of almost all modem automobiles (see Exhaust control, automotive). It is an electrochemical sensor that uses a soHd electrolyte, often doped Zr02, as an oxygen ion conductor. The sensor exemplifies many of the properties considered desirable for all chemical microsensors. It works in a process-control situation and has very fast (- 100 ms) response time for feedback control. It is relatively inexpensive because it is designed specifically for one task and is mass-produced. It is relatively immune to other chemical species found in exhaust that could act as interferants. It performs in a very hostile environment and is reHable over a long period of time (36). 

Sohd tantalum capacitors have a high volumetric capacitance which makes them attractive for use in miniaturized electronic systems like cellular telephones, hand-held video cameras, and personal computers. The insensitivity of their capacitance to temperature and their abiUty to operate at temperature extremes explains why these devices are used in such harsh environments as automobile engine compartments. Sohd tantalum capacitors are extremely rehable and, therefore, are often the capacitor of choice in critical appHcations like spacecraft electronics, pacemakers, and safety equipment. 

Fig. 5.2. Changes that take place when an automobile moves in a thermally insulated environment at constant temperature Tq and pressure pt). The environment is token to be large enough that the change in system volume V2 - V, does not increase p, and the flow of heat Q across the system boundary does not affect Tq.

In order to see why, we need to look at our car in a bit more detail (Fig. 5.2). We start by assuming that it is surrounded by a large and thermally insulated environment kept at constant thermodynamic temperature Tq and absolute pressure po (assumptions that are valid for most structural changes in the earth s atmosphere). We define our system as (the automobile -1- the air needed for burning the fuel -1- the exhaust gases... 

Besides all the gaseous and liquid wastes of transportation that result from energy use, and the loss of natural environment to roadv ays, there is also the solid-waste problem of disposal— vehicles and components such as tires and batteries. Responding to the growing disposal problem, many manufacturers are building automobiles that contain far more recyclable parts. 

Table 9.1 includes estimates of potential savings published in 1971. The variations in the ratio of savings to costs are in part due to differences in the extent to which severely corrosive environments are characteristic of the industry concerned. However, the differences also reflect the uneven level of corrosion awareness when the estimates were made, and as significant improvements in practices have occurred, the detailed figures do not entirely represent the current situation. For example, corrosion of cars is now a much smaller problem than it was in 1970. The automobile industry is also an... 

Hasanen E, Soininen V, Pyysalo M, et al. 1979. The occurrence of aliphatic chlorine and bromine compound in automobile exhaust. Atmos Environ 13 1217-1219. 

Jerome O. Nriagu. The Rise and Fall of Leaded Gasoline. The Science of the Total Environment. 92 (1990) 13-28. An authoritative history of leaded gasoline. The source for airplane octane lead industry pays Kehoe s salary one of few environmentally unsafe products forced out of market place one of top 10 chemicals in U.S. Esso slogan compression ratio and valve seat recession Kettering about automobile at crossroads, Europe versus U.S. 90 percent all U.S. gas and 80 percent worldwide autos after 20 years of TEL TEL drove U.S. transport lead removed from Ethyl trade name and Ethyl s control of publications and environment to be monitored by voluntary self-regulation, not legislation. 

It is important in defining any analysis scheme that the analysis elements be consistent in scope, scale, and detail with each other and with the purposes of the analysis. Thus details of cohort exposure in microenvironments can provide valuable information on populations at risk if, in fact, pollutant concentrations are functions of micro-environments. It appears that micro-environments are clearly important in carbon monoxide (CO) exposure analysis because automobile generated CO concentrations are highly correlated with automobile usage patterns. It is not clear that ozone exposures are so correlated. Ozone commonly exists in "clouds" that are large compared to any one micro-environment, but drift over an area large compared to their size in the course of their formation and decay. 

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