ASSIGNMENT 1
Name: _________________________________
Student ID: _____________________________
MEE 3223/MEE 4206: ENGINEERING THERMODYNAMICS 2
ASSIGNMENT 1
GIVEN: 27/02/2015
DUE DATE: 16/03/2015
ANSWER ALL QUESTIONS
Q1. A two-stroke, four cylinder Diesel engine operates on an ideal Diesel cycle. The engine has a capacity of 2.5 L, compression ratio of 18 and cutoff ratio of 2.2. At the beginning of the compression process, the is at 50°C and 100 kPa. Using the cold-air standard assumptions, determine how much power the engine will deliver at 3000 rpm.
Q2. The net output of a steam power plant is 120 MW. The plant operates on on an ideal reheat-regenerative Rankine cycle. At the inlet of the high pressure turbine, the steam pressure and temperature are 10 MPa and 550oC respectively. The steam leaves the high pressure turbine at 0.8 MPa. Some of the steam leaving the high pressure turbine is extracted and supplied to an open feedwater heater, while the rest is reheated to 500oC. The reheated steam is expanded in the low-pressure turbine. The steam leaves the low-pressure turbine at 10 kPa. Sketch the cycle on a T-s diagram and determine
(a) mass flow rate of the steam through the boiler
(b) thermal efficiency of the cycle.
Q3. The gas-turbine portion of a combined gas-steam power plant has a pressure ratio of 15. Air enters the compressor at 32°C at a rate of 15 kg/s and is heated to 1500 K in the combustion chamber. The combustion gases leaving the gas turbine are used to heat the steam to 400°C at 10 MPa in a heat exchanger. The combustion gases leave the heat exchanger at 430 K. The steam leaving the turbine is condensed at 10 kPa. Assuming all the compression and expansion processes to be isentropic, determine
(a) the mass flow rate of the steam,
(b) the net power output, and
(c) the thermal efficiency of the combined cycle.
For the gas turbine cycle, use the cold air standard assumptions.