ES 202 Fluid and Thermal Systems Examples for Lecture 18 1 23 03 Page 1 1 A closed rigid container of volume 0 5 m3 is placed on a hot plate Initially the container holds a two phase mixture of saturated liquid water and saturated water vapor at a pressure of 1 bar with a quality of 0 5 After heating the pressure in the container is 1 5 bar a Determine the temperature and mass of vapor at the initial and final states vapor liquid b If heating continues determine the pressure when the container holds only saturated vapor c Sketch the process paths on a P v a T v and a P T diagram clearly indicates the two phase region 2 Water contained in a piston cylinder assembly undergoes two processes in series from an initial state where the pressure is 10 bar and the temperature is 400 deg C Process 1 The water is cooled as it is compressed at a constant pressure of 10 bar to the saturated vapor state Process 2 The water is further cooled at constant volume to 150 deg C a Determine the overall work for the overall process b Determine the overall heat transfer for the overall process water c Sketch the whole process path on a P v a T v and a P T diagram clearly indicates the two phase region ES 202 Fluid and Thermal Systems Examples for Lecture 18 1 23 03 Page 2 3 A mass of 12 kg of saturated refrigerant 134a vapor is contained in a piston cylinder device at 200 kPa Now 150 kJ of heat is transferred to the refrigerant at constant pressure while a 110V source supplies current to a resistor within the cylinder for 6 minutes Process A a Determine the current supplied if the final temperature is 70 deg C vapor liquid b If a latch is placed on the wall of the cylinder to restrain motion of the piston Process B from the beginning what do you expect to be the main difference Determine the current in this case c Show the process on a P v a T v and a P T diagram clearly indicates the twophase region d If the refrigerant is replaced by an ideal gas how would you solve the problem differently
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