Calculate the following.

Question

The temperature of product of combustion in a boiler decreases from 1100⁰C to 550⁰C while the pressure remains constant at 0.1 MPa. Water at 0.8 MPa, 150⁰C is converted into steam at 0.8 MPa, 250⁰C with the surroundings is at 100 kPa and 25⁰C. Sketch the control volume depicting the terminal and process conditions and show on a T-s diagram the processes. Calculate the following.

1. change in availability of water on unit mass of water basis.
2. change in availability of product of combustion per kg of water.
3. process irreversibility per unit mass of water
4. second law efficiency, and
5. entropy generated per kg of water.

Take average specific heat of product of combustion as 1.09 kJ/kg-K. Specify enthalpy and specific entropy of water at 0.8 MPa, 150⁰C are, respectively, at 632.2 kJ/kg and 1.8418 kJ/kg-K and that the steam at 0.8 MPa, 250⁰C are respectively at 2950 kJ/kg and 7.0389 kJ/kg-K.