Question

Define turbine efficiency, generator efficiency, and combined turbine- generator efficiency.

Short answer

Answer: The combined turbine-generator efficiency represents the overall efficiency of the entire energy conversion process, from the working fluid's energy to the electrical energy output. It takes into account the efficiencies of both the turbine and the generator. It is calculated as the product of the turbine efficiency and the generator efficiency: \(\eta_{combined} = \eta_t \times \eta_g\).

Step-by-step solution

Define turbine efficiency

Turbine efficiency is defined as the ratio of the actual work output of the turbine to the ideal (theoretical) work output. In other words, it is the measure of how effectively a turbine converts the energy in the working fluid (gas or steam) into mechanical work. Mathematically, turbine efficiency (\(\eta_t\)) can be expressed as: \(\eta_t = \frac{Actual\,work\,output}{Ideal\,work\,output} \) An ideal turbine is assumed to be adiabatic and reversible i.e., there is no heat loss and it has the maximum possible conversion of energy. In practice, the actual work output will be lower than the ideal value due to irreversibilities and inefficiencies.

Define generator efficiency

Generator efficiency is the ratio of the electrical power output of the generator to the mechanical power input. This is the measure of how efficiently the generator converts mechanical energy from the turbine into electrical energy. Mathematically, generator efficiency (\(\eta_g\)) can be expressed as: \(\eta_g = \frac{Electrical\,power\,output}{Mechanical\,power\,input} \) A generator experiences losses due to various factors like resistive heating, hysteresis, and eddy current losses; hence the electrical power output will be lesser than the mechanical power input.

Define combined turbine-generator efficiency

The combined turbine-generator efficiency represents the overall efficiency of the energy conversion process right from the working fluid's energy to electrical energy output. It considers both the efficiencies of the turbine and generator. Mathematically, the combined turbine-generator efficiency (\(\eta_{combined}\)) can be expressed as the product of the turbine efficiency and the generator efficiency: \(\eta_{combined} = \eta_t \times \eta_g\) The combined efficiency will provide us with valuable information on the overall performance of the energy conversion system and help to identify areas for improvement.