Determination of the final pressure and volume of the system A = 3.14 / 4 * ( D * 10 **- 2 ) ** 2 # Area of the cylinder p1 = 0.7449 # Initial pressure of saturated vapour at 30 degree celcius in MPa v1 = 0.023508 # Initial specific volume of saturated vapour at 30 degree celcius in m^3/kg p2 = ( patm * 10 ** 5 ) + ( m * g ) / A # Final pressure of Freon 12 v2 = 0.084022 # Final specific volume from superheated table at p2 and 30 degree celcius in m^3/kg mf = V1 / v1 # Mass of Freon 12 V2 = mf * v2 # Final volume of Freon 12 #Result for (a) print "(a)", " \n Final pressure = ", p2, "Pa", " \n Final volume = ", round ( V2, 5 ), "m^3 (round off error)" #Calculation for (b) # (b). ![]() Import math from _future_ import division #Variable declaration patm = 1 # Atmospheric pressure in bar V1 = 0.0135 # Volume of Freon 12 at initial state in m^3 D = 9 # Diameter of the cylinder in cm m = 90 # Mass of the piston in kg g = 9.80665 # acceleration due to gravity in m/s^2 #Calculation for (a) # (a). Import math from _future_ import division #Variable declaration p1 = 5 # Pressure of Helium gas at initial state in bar T1 = 222 # Temperature of Helium gas at initial state in K V1 = 0.055 # Volume of Helium gas at initial state in m^3 n = 1.5 # Index of expansion process R = 2.078 # Characteristic gas constant of Helium gas in kJ/kg K p2 = 2 # Pressure of Helium gas at final state (after expansion) in bar #Calculation for Method I V2 = V1 * ( p1 / p2 ) ** ( 1 / n ) # From Polytropic process relation for final volume W = (( p2 * 10 ** 2 * V2 ) - ( p1 * 10 ** 2 * V1 )) / ( n - 1 ) # Work done from Polytropic process relation #Result for Method I print "Method I" print " \n Work done =", round ( W, 2 ), "kJ" #Calculation for Method II m = ( p1 * 10 ** 2 * V1 ) / ( R * T1 ) # ideal gas equation T2 = T1 * ( p2 / p1 ) ** (( n - 1 ) / n ) # From Polytropic process relation of final temperature W = ( m * R * ( T1 - T2 )) / ( 1 - n ) # Work done from Polytropic process relation #Result for Method II print " \n\n Method II" print " \n Work done =", round ( W, 2 ), "kJ"
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