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

0.8 kilograms of fuel are consumed each second.

Step-by-step 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) = (\dot W)/(\dot E) * 100\,\%`

The fluid power is:

`\dot E = (\dot W)/(\eta) * 100\,\%`

`\dot E = (8\,MW)/(20\,\%)* 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\,(MJ)/(kg) = (40\,MJ)/(m_(fuel))`

`m_(fuel) = 0.8\,kg`

0.8 kilograms of fuel are consumed each second.