Question

What is "efficiency" in general? Consider a turbine and an electrical generator. Define turbine efficiency, generator efficiency and combined efficiency. Both turbine and generator suffer losses. Explain where these losses originate.

Answer 1

In general means efficiency is defined as ratio of output and input.

$\eta =\frac{Output}{Input}$

Turbine efficiency is given by actual work output of the turbine divided by input energy given to turbine in the form of fuel.

For electrical generator efficiency is given by heat used by generator to produced electricity divided by heat given to generator.

Combined efficiency can be defined by output electrical energy generated by generator divided by input energy given to turbine in form of fuel.

Losses in Turbine- Windage losses (due to air resistance to the rotation of shaft), friction of turbine can reduce output.

Losses in Generator- Cooper loss or winding loss (due to current flowing through winding). This loss is generating due to resistance of winding and create Joule heat. Hysteresis of iron core can also reduce output.

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