Vehicle Engines - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 132

Chapter 9
Vehicle Engines
Internal combustion engines use fossil fuels. They determine the typical con-
struction of transportation means by transforming the chemical energy in fuel into
mechanical power. The principle is common in vehicles, airplanes, ships and
portable machines (see Table 9.1 )[ 1 ].
In construction machines and tractors, internal combustion engines are
advantageous since they can provide a high power-to-weight ratio usually with
excellent fuel energy density. Gas turbines are used where very high power is
required, such as in generators in the energy industry, in jet engines of airplanes
and in the auxiliary equipment of ships.
Performance standards and requirements for internal combustion engines have
intensively increased over the last decades (see Fig. 9.1 ).
9.1 Principles of Operation
There are three basic operation principles of engine systems:
• Internal combustion engine:
- Two-stroke cycle with one up and one down movement for every power
stroke [ 2 ]
- Four-stroke cycle with two up-down-up-down movements for every power
stroke [ 3 ]
• Rotary engine, e.g. Wankel engine [ 4 ]
• Continuous combustion engine which operates with the Brayton cycle [ 5 ]
- Gas turbine, e.g. in jet engines, including turbojets, turbofans, turboprops,
prop fans, ramjets, rockets, etc. They operate without separate phases, instead
perform them simultaneously.