Question

A steam turbine receives steam with a specific enthalpy of 3117 kJ/kg at a rate of 5 kg/s. At the turbine outlet, the specific enthalpy of the steam is 2851 kJ/kg. Find the turbine power in kW.

Answer 1

To find the turbine power, we need to calculate the change in specific enthalpy and multiply it by the mass flow rate of the steam.

The change in specific enthalpy is given by:

h = h2 - h1

where h1 is the specific enthalpy at the turbine inlet and h2 is the specific enthalpy at the turbine outlet.

Given:
h1 = 3117 kJ/kg
h2 = 2851 kJ/kg
mass flow rate = 5 kg/s

h = 2851 kJ/kg - 3117 kJ/kg
h = -266 kJ/kg

Now, we can calculate the turbine power using the formula:

Power = mass flow rate * h

Power = 5 kg/s * -266 kJ/kg

Since power is typically measured in kilowatts (kW), we need to convert the units:

Power = 5 kg/s * -266 kJ/kg * (1 kW / 1000 J)
Power = -1.33 kW

The negative sign indicates that the turbine is producing power, as energy is being extracted from the steam.

Therefore, the turbine power is 1.33 kW.