Final answer:
A small fraction of air passing through a turbine engine is used in the combustion process, with a typical fuel-air ratio of 15:1. The efficiency of turbine engines is about 40-50%, while internal combustion engines have an efficiency of approximately 25-30%. Power plants have efficiencies ranging from 40% to over 50% depending on the technology used.
Step-by-step explanation:
Of the air passing through a turbine engine, a small fraction is involved with the combustion process and the fuel-air ratio is typically about 15:1 in modern jet engines. During this process, air is mixed with fuel during the intake stroke, compressed during the compression stroke, and ignited to perform work on the piston in the power stroke. Efficiency rates for these engines vary, with modern turbines operating at 40-50% efficiency due to improved design and technology.
For internal combustion engines like those in cars, the efficiency is significantly lower, typically about 25% to 30%. The reason for this reduced efficiency is due to various irreversible processes, such as friction and heat exchange, and preignition issues in gasoline engines that can cause engine knock and further loss of power.
In contrast, power plants have varied efficiency ratings: coal power plants convert about 40% of the energy, nuclear power plants more than 50%, and gas turbines can approach 60% efficiency, especially when coupled with co-generation, which can raise overall efficiency by another 10-15%.