SHORT ANSWER: No GOAL write-up needed. But clearly show SKETCH, PROPERTY TABLE,
ID: 1861059 • Letter: S
Question
SHORT ANSWER: No GOAL write-up needed.
But clearly show SKETCH, PROPERTY TABLE, MASS & ENERGY BALANCE EQUATIONS FOR EACH.
a) A rigid tank containing 20 kg of Refrigerant 134a as saturated vapor at 1.0 bars and -26.43 oC is
heated until the temperature reaches 20 oC. The final volume of the R-134a is __________ m3
.
b) A rigid tank with a volume of 5.0 m3 contains Refrigerant 134a at -16 oC and mixture quality of 25
%. The total mass of the R-134a is ______________ kg.
c) A rigid tank containing 20 kg of Refrigerant R-134a at 6.0 bars and 140 oC is cooled causing the
pressure to fall to 4.0 bars. The final temperature is _____ oC.
d) Twenty kilograms (20 kg) of Refrigerant R-134a contained in a piston-cylinder device initially at
6.0 bars and 140 oC is cooled at constant pressure to the saturated liquid state. The specific
internal energy of the saturated liquid is ____________ kJ/kg.
Explanation / Answer
a) At 1 bar for sat. vapor (quality = 1) we get v = 0.193 m^3/kg
Volume V = mv = 20*0.193 = 3.86 m^3
=====================================
b) At -16 deg C and quality = 0.25 we get v = 0.0319 m^3/kg
Mass m = V/v = 5 / 0.0319 = 156.74 kg
=====================================
c) At 6 bars, 140 deg , we get v = 0.054 m^3/kg
Density = 1/0.054 = 18.519 kg/m^3
At 4 bars and density = 18.519 kg/m^3, we get T = 19.2 deg C
=====================================
d) At 6 bars and quality = 0 (sat.liquid) we get u = 81000 J/kg
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