# Mini Project 3

```SCB 23603 Thermal Science
Jan 2021
MINI PROJECT 3
TOTAL MARKS = 35
This is an individual assignment. Only handwritten assignments will be accepted. Late
submission will be penalised (10% deduction per a day late). Submit your work in pdf
format via the VLE. Answer all questions.
Due date is 26 April 2021, 11.59 pm.
Question 1
Steam flows steadily into an adiabatic turbine with a mass flow rate of 6 kg/s. The inlet and the
exit conditions are given in Figure 1. Neglect potential energy. Determine:
i.
The power output of the turbine. (8 marks)
ii. The turbine inlet area. (3 marks)
P1 = 2 MPa
T1 = 400oC
V1 = 50 m/s
P2 = 15 kPa
x = 0.9
V2 = 180 m/s
Figure 1
1
SCB 23603 Thermal Science
Jan 2021
Question 2
Air is compressed in a compressor from a pressure of 100 kPa and a temperature of 17&ordm;C to a
pressure of 1000 kPa. Heat is removed from the compressor at a rate of 70 kW by circulating
water through the compressor casing. The volumetric flow rate of the air at the inlet conditions is
150 m3/min, and the power input to the compressor is 550 kW.
i.
Determine the mass flow rate of air. (2 marks)
ii.
Calculate the temperature at the compressor exit. (7 marks)
Question 3
As shown in Figure 3, a steam turbine at steady state is operated at part load by throttling the
steam to a lower pressure before it enters the turbine. Before throttling, the pressure
and temperature are, respectively, 1.4 MPa and 350&deg;C. After throttling, the pressure is 1 MPa. At
the turbine exit, the steam is at 0.075 bar and a quality of 90%. Heat transfer with the surroundings
and all kinetic and potential energy effects can be ignored. Determine:
i.
the temperature at the turbine inlet, in &deg;C. (9 marks)
ii. the power developed by the turbine, in kJ/kg of steam flowing. (6 marks)
P1 = 1.4 MPa
T1 = 350&deg;C
P3 = 7.5 kPa
x = 90%
Figure 3
2
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