Question 1 (25 marks)
(a) Steam undergoes a change from an initial state of 450deg C and 3000kPa to a final state
of 150deg C and 235kPa. Determine Delta H and Delta S :
(i) From steam-table data;
(ii) Using the ideal gas law;
(iii) In which of your answer in (i) and (ii) above do you have more confidence and
briefly explain why.
Data: (C_(P))/(R)=3.470+1.45 imes 10^(-3)T+(0.121 imes 10^(5))/(T^(2))
(5+5+2 marks)
(b) In a trial run conducted on the ChBE pilot power plant, the steam turbine operates
adiabatically with a steam rate of 25k(g)/(s). The turbine receives steam at 1300kPa and
400deg C and discharges at 40kPa and 100deg C. Determine the power output of the turbine
and the efficiency of its operation in comparison with a turbine that operates reversibly
and adiabatically from the same initial conditions to the same final pressure.
(13 marks)
Question 1(25 marks
(a)
(i) (ii) (iii)
From steam-table data; Using the ideal gas law;
briefly explain why.
T2
5+5+2 marks
Data:
(b)
In a trial run conducted on the ChBE pilot power plant, the steam turbine operates adiabatically with a steam rate of 25 kg/s. The turbine receives steam at 1300 kPa and 400 C and discharges at 40 kPa and 100 C. Determine the power output of the turbine and the efficiency of its operation in comparison with a turbine that operates reversibly and adiabatically from the same initial conditions to the same final pressure. 13 marks)