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Unformatted text preview: 4-9A piston-cylinder device with a set of stops contains steam at a specified state. Now, the steam is cooled. The compression work for two cases and the final temperature are to be determined. Analysis(a) The specific volumes for the initial and final states are (Table A-6) /kgm23275.C250MPa1/kgm30661.C400MPa132223111=°===°==vvTPTPNoting that pressure is constant during the process, the boundary work is determined from kJ22.16=-=-=/kgm)23275.30661.kPa)(kg)(10003.()(321vvmPWb(b) The volume of the cylinder at the final state is 60% of initial volume. Then, the boundary work becomes kJ36.79=×-=-=/kgm)30661.60.30661.kPa)(kg)(10003.()60.(311vvmPWbThe temperature at the final state is C151.8°=×==2322/kgm)30661.60.(MPa5.TPv(Table A-5) 4-35An insulated rigid tank is initially filled with a saturated liquid-vapor mixture of water. An electric heater in the tank is turned on, and the entire liquid in the tank is vaporized. The length of time the heater was kept on is to be determined, and the process is to be shown on a P-vdiagram. Assumptions1 The tank is stationary and thus the kinetic and potential energy changes are zero. 2 The device is well-insulated and thus heat transfer is negligible. 3 The energy stored in the resistance wires, and the heat...
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This note was uploaded on 01/25/2010 for the course ME 55806 taught by Professor Chen during the Spring '10 term at Berkeley.
- Spring '10