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# Ps2 - ME 212 PS I 26.02.2009 1 The compression ratio of an...

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Unformatted text preview: ME 212 PS I! 26.02.2009 1) The compression ratio of an air-standard Otto cycle is 9.5. Prior to the isentropic compression process,.the air is at 100 kPa, 35°C, and 600 cm3. The temperature at the and of the isentropic expansion process is 800 K. Using specific heat values at room temperature, determine (a) the highest temperature and pressure in the cycle; (b) the amount of heat transferred in, in kJ; (c) the thermal efficiency; and (d) the mean effective pressure. 2) An ideal diesel engine has a compression ratio of 20 and uses air as the working fluid. The state of air at the beginning of the compression process is 95 kPa and 20°C. if the maximum temperature in the cycle is not to exceed 2200 K, determine (a) the thermal efﬁciency and (b) the mean effective pressure. Assume constant specific heats for air at room temperature. 3) Consider an ideal Ericsson cycle with air as the working fluid executed in a steady—flow system. Air is at 27°C and 120 kPa at the beginning of the isothermat compression process, during which 150 kJ/kg of heat is rejected. Heat transfer to air occurs at 1200 K. Determine (a) the maximum pressure in the cycle, (b) the net work output per unit mass of air, and (C) the thermal efficiency of the cycle. i 4) An ideal Stirling engine using helium as the working fluid operates between temperature limits of 300 and 2000 K and pressure limits of 150 kPa and 3 MPa. Assuming the mass of the helium used in the cycle is 0.12 kg, determine (a) the thermal efficiency of the cycle, (b) the amount of heat transfer in the regenerator, and (c) the work output per cycle.» ‘ ...
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