Question

A gas turbine has a thermal efficiency of 20% and develops a power output of 8 MW. Determine the fuel consumption rate if heating value of the fuel is 50 MJ/kg

Answer 1

Answer:

0.8 kilograms of fuel are consumed each second.

Explanation:

As turbines are steady-state devices, the thermal efficiency of a turbine is equal to the percentage of the ratio of the output power to fluid power, that is:

$\eta_{th} = \frac{\dot W}{\dot E} \times 100\,\%$

The fluid power is:

$\dot E = \frac{\dot W}{\eta} \times 100\,\%$

$\dot E = \frac{8\,MW}{20\,\%}\times 100\,\%$

$\dot E = 40\,MW$

Which means that gas turbine consumes 40 megajoules of fluid energy each second, which is heated and pressurized with help of the fuel, whose amount of consumption per second is:

$50\,\frac{MJ}{kg} = \frac{40\,MJ}{m_{fuel}}$

$m_{fuel} = 0.8\,kg$

0.8 kilograms of fuel are consumed each second.