A piston cylinder device has been designed so that heat can beadded or removed f

Question

A piston cylinder device has been designed so that heat can beadded or removed from the fluid in the cylinder. The cylinderstarts out with 0.1m3 of liquid water and 0.9m3 of water vapor in equilibrium at a pressure of 800kPa. Heat is transferred so that the pressure in the cylinderremains constant until the temperature reaches 350 deg C.

a.                  What is the initial temperature of the water, deg C?

b.                 Determine the total mass of the water, kg.

c.                  Calculate the final volume, m3

Explanation / Answer

since pressure remains constant at p2=800kpa and T2=350C from steamtables v2=0.35439m3/kg initial state of the cylinder is in wet conditionx1=0.9/(0.9+0.1)                                                                        =0.9 initial state is in wet condition,at p1=800kPa fromsteam tables the saturation temperature is equal to initialtemperature T1=170.4C b) cylinder volume V1 =0.9+0.1                                  =1m3 at p1= 800kPa from saturated steam tables vf=0.001115m3/kg vfg=0.23931m3/kg v1=vf+x1vfg    =0.2165m3/kg m=V1/v1    =1/0.2165 m=4.1689kg c) at p2=800kPa and T2=350C fromsteam tables v2=0.35439m3/kg V2=mv2     =4.1689*0.35439   V2=1.4774m3     =4.1689*0.35439   V2=1.4774m3

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