Special Problems for ME 200 – Fall 2011 Special Problems 8, 9, and 10 Due Friday, September 16, 2011 SP8: A piston-cylinder device contains a gas undergoing a series of processes in a cycle. The gas is initially at 0.95 bar and 20 C occupying 5700 cm 3 (state 1). Adiabatic compression occurs to 25 bar and 465 C during which the volume reduces to one-tenth of the initial volume (state 2). Constant pressure expansion occurs so that the gas occupies 1710 cm 3 and its temperature is 1940 C (state 3). Adiabatic expansion occurs to 4.45 bar and 1095 C (state 4). The cycle is completed with constant volume process. The values of internal energy of the gas at various states in the cycle are: U 1 = 1.47 kJ, U 2 = 3.67 kJ, U 3 = 11.02 kJ, and U 4 = 6.79 kJ. (a) Sketch the cycle on P-V diagram. Label the states and show property values. (b) Calculate the work (kJ) and heat transfer (kJ) for each process in the cycle. (c) What is the net work (kJ) for the cycle?
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