Tep tut2 - Applied Thermodynamics and Heat Transfer Tutorials 3rd Year 1st Semester PDF

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Applied Thermodynamics and Heat Transfer Tutorials 3rd Year 1st Semester...

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CURTIN UNIVERSITY OF TECHNOLOGY Department of Mechanical Engineering Thermal Engineering Processes 331 Tutorial 2 1

An adiabatic turbine of a steam power plant receives steam at 80 bar and 500 oC and produces 100 MW of power. The isentropic efficiency of the turbine is estimated to be 0.85. The turbine discharges steam to a condenser at 0.07 bar. Calculate mass flow rate of the steam through the turbine. If the cooling water enters the condenser at 20 oC and leaves at 35 oC, calculate the cooling water flow rate required to condense the exhaust steam from the turbine to saturated water state at the condenser outlet. Determine the overall efficiency of the plant neglecting the feed pump work. Ans: 89.8 kg/s, 3037.7 kg/s, 0.344

2

A steam power plant operates with an ideal regenerative Rankine cycle using an open feedwater heater. The boiler generates superheated steam at 10 MPa and 550 oC. Regenerative steam for feed heating is extracted at 1000 kPa. The condenser pressure is 10 kPa. Find the cycle efficiency and compare it with that of an ideal Rankine cycle without regeneration.

Ans. 43.8 oC, 41.0 %

3

In a steam power plant operating on a regenerative Rankine cycle with reheat, the steam enters the turbine at 8.5 MPa and 540 oC, and expands isentropically to 2.2 MPa, where some steam is extracted for feed heating with an open feed heater while the remainder is reheated to 500 oC and sent back to the turbine for further expansion. The steam exhausts from the turbine at 7 kPa and 240 m/s. The cooling water enters the condenser at 20 oC and leaves at 30 oC. The power plant produces 60 MW of power. Determine the steam flow rate and the cooling water flow rate. Ans. 47.25 kg/s, 1784 kg/s

4

A refrigerator uses Freon -12 as the working fluid and operates on the ideal refrigeration cycle. The condensing temperature and the evaporating temperature of the refrigerant are 40 oC and -15 oC, respectively. Determine the coefficient of performance. Calculate the refrigeration effect if the mass flow rate is 0.05 kg/s. Ans: 3.61, 5.32 kW

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