Thermodynamic properties of a fluid and the fundamental principles governing the mechanical and thermal fluid characteristics
Apply the First Law of Thermodynamics to analyse the behaviour of a thermodynamic cycle (S&E)
Task 1
A combined gas-steam power plant (Rankine and Brayton cycles) operates with air entering the compressor at 103 kPa and 300°K. The compressor pressure ratio is 7 The air leaves the heat addition process at 1076 °C. The compressor isentropic efficiency is 79% and the gas turbine is 88%. The air leaves the gas-steam heat exchanger at temperature of 200°C. The gas-steam heat exchanger operates at 9" efficiency. Steam flows to the heat exchanger with pressure of 52 bar and leaves at 377°C. The condenser pressure is 0.06 bar. The isentropic efficiency of steam turbine is 88%.
Analyse the given power plant with following assumptions
1. Changes in KE and PE ore negligible
2. Air is an ideal gas
3. Brayton cycle to be calculated by using the air table properties
4. Operation of the plant is steady at no losses
Determine:
1. The air mass flow of Brayton cycle in order to produce 3800 kW of net power
2. The net power of Rankine cycle
3. The overall efficiency
4. Draw the T-s diagram and block diagram of this plant (see Appendix 1)
Task 2
Consider a round nozzle directing the water jet on the flat plate as per below picture. The water jet exerts force of 89 N on the flat plate, Assuming steady flow and neglecting frictions, determine the following:
a) The velocity at nozzle exit
b) The mass flow of water
c) The velocity at nozzle entrance
d) The manometer reading (mercury filled) if D1 is 8 cm and D2 is 3 cm
Apply the First Low of Thermodynamics to reversible non-flow processes (A&4) -flow processes
Task 3
A cylinder filled with air, shown on the right side, having stop at height, h of 1.30 m and a frictionless piston with area A of 0.4 m?, at initial
state P1 = 177 kPa and T1 = 586 °C, is cooled down to 20 °C. Apply the First Law of Thermodynamics and analyze
1. The process when the piston reaches the stops
2. The process when air reaches final temperature
3. Sketch and label T-V, P-V and P-T diagrams
