Noise pollution, engines

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... 

After operating for several hours, a flow deviation is still observed that can be considered as acceptable because the automotive manufacturer has taken it into account during the development of the engine. On the other hand, a more pronounced trend such as that shown in Figure 5.18 would be unacceptable because it will affect the engine noise, driving comfort and pollutant emissions. 

L. K. Wang and N. C. Pereira, eds.. Handbook of Environmental Engineering Vol. 1—Air and Noise Pollution Control, The Humana Press, CHfton, N.J., 1979. 

Jensen, P. Noise control. In Handbook of Environmental Engineering, Volume 1, Air and Noise Pollution Control Wang, L.K., Pereira, N.C., Eds. Clifton, NJ 1979, 411-474. 

Many engineers are aware of the need to reduce noise pollution, and some of them are busy devising new ways to solve the noise problem. In Japan, Yokohama... 

Another customer requirement is a silent and vibration free operation of the iCHP system in the house to reduce or eliminate noise pollution. Fuel-cell systems have nearly no rotating parts, except blowers or pumps, which could cause noise pollution in opposite to combustion engines. Logically consistent fuels cells support a very silent energy conversion of chemical energy into electrical energy. This potential of silent operation is still used commercially in submarines. 

Engineers select and evaluate process equipment. The selected equipment must be technically sound, rehable, safe and easy to operate, serviceable, economically attractive and environmentally sound, e.g. minimal noise pollution and no mechanical and fire hazards. For example, all pneumatic valves, except for the modulating valves, are air-to-open/ spring-to-close valve type for safe shutdown unless the valve is a divert drain valve as... 

In Chap. 27 Alain Biahmou discusses the concept of sustainable mobility as a field of application of Concurrent Engineering. In particular, the electrical power train of road vehicles has an increasingly significant role. Besides delivering benefits in air and noise pollution, it encompasses huge challenges in practical usability. 

The noise emission from road vehicles is limited by legislation in order to protect the environment against high noise pollution. The related noise limits were significantly reduced over the last 30 years (Fig. 8.21) [148]. Predominant noise sources are tires, exhaust systems, intake systems, power-train and combustion engine. Purely passive systems like exhaust mufflers. 

The soimd radiated by the rotorcraft into its environment is what the critical observer perceives as noise pollution and what delivers a characteristic acoustic signature for aircraft detection and classification. The tjq)ical rotor-craft sound is composed of several components with destinctive directivity and intensity, depending on the flight conditions. In general, at a distance, the main rotor noise is dominant, the high frequency emissions of the tail rotor have some relevance, and the engine noise is secondary. 

Due to strict environmental regulations, turbine engine manufacturers and users are facing great challenges in reducing NO, SO , CO, and hydrocarbons to meet the compliance limits. To date, several innovative methods have been developed and introduced into the market to combat these problems. However, often, while reducing NOj, or other pollutants, new problems arise. These problems are lower turn-down ratio, poor thermal efficiency, flame instability, uneven temperature distribution in the combustor, and noise. These problems are even more pronounced in a liquid fuel fired turbine combustor. Therefore, the present research... 

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