课程名称︰热力学 课程性质︰必修 课程教师︰许文翰 开课学院：工学院 开课系所︰工程科学与海洋工程学系 考试日期（年月日）︰2008/6/19 考试时限（分钟）：120 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : Thermodynamics Final 6/19/2008 1.An ideal-gas turbine operates with a pressure ratio of 8:1 and temperature limits of 20'C(度C) and 1000'C. The energy input in high temperature that exchanger is 200kW. Determine (a) the air flowrate; (b)the percentage of turbine work used by the compressor.(20pt) 2.An engine operates on the air-standard Otto cycle. The pressure and temperature at the beginning of isentropic compression are 120kPa and 35'C respecticvely. The peak pressure and temperature are 4.8MPa and 2500'C. Determine (a) the net cycle workin kJ/Kg; (b)the cycle efficiency. (20pt) 3.An air-standard Diesel cycle receives 28.5kJ/cycle of heat while operating at 300rev/min. At the beginning of compression, p1=100kPa, T1=305K, V1=0.0425m^3. At the beginning of heat addition, the pressure is 3450kPa. Determine (a) the work; (b) the power, (c) the mean effective pressure. (20pt) 4.A reciprocating compressor has a 5% clearance with a bore and stroke of 25cm and 30cm. The compressor operates at 500rev/min. The air enters the cylinder at 27'C and 95kPa and discharges at 2000kPa. If n=1.3 for compression and expansion processes. Determine (a)the volumnetric efficiency; (b) the power required; (c)the mass of air discharged in kg/s. (20pt) 5.A gas turbine expands 50kg/s of Helium polytropically, pV^1.8=C, from 1100K and 500kPa to 350K. Determine (a) the entropy change; (b)the final pressure; (c)the heat loss. (20pt) --

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