A vertical piston-cylinder device initially contains 12 kg of refrigerant R-134a, 9 kg of which is...

 

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A vertical piston-cylinder device initially contains 12 kg of refrigerant R-134a, 9 kg of which is in the liquid phase. The mass of the stainless-steel piston helps to maintain a constant pressure of 400 kPa inside the piston-cylinder. A stream of R134-a at 0.9 MPa and 90°C is allowed to enter the piston-cylinder from a supply line until all the liquid in the cylinder has vaporized. The piston-cylinder is placed in an air-conditioned room, so there is a heat loss of 4500 J from the system. Furthermore, there is a rotating shaft that attached to the piston- cylinder, which is used to agitate the R-134a for better mixing. W. Electric motor Wsh Shaft Vapor Liquid Valve Control volume Inlet stream is used to agitate the R-134a for better mixing. W. Electric motor Q Wsh Shaft Vapor Liquid Valve Control volume Inlet stream (a) Determine the initial phase and properties (temperature, specific volume, internal energy, enthalpy, and entropy) of the R-134a inside the piston-cylinder. (6 Marks) (b) Determine the final phase and properties (temperature, specific volume, internal energy, enthalpy, and entropy) of the R-134a inside the piston-cylinder. (6 Marks) (c) Identify the phase and properties [quality (determine if applicable), specific volume, 3 mes energy, enthalpy, and entropy) of the R-134a inside the piston-cylinder. (6 Marks) (c) Identify the phase and properties [quality (determine if applicable), specific volume, internal energy, enthalpy, and entropy] of the R-134a in the inlet stream. (6 Marks) (d) The rotating shaft is externally powered by the electric motor, which operated at 200 V and 2.7 A. The electric motor supplies the electric work to the shaft to generate the shaft work. If the influx process of R-134a stream took place for 0.5 h, calculate the electric work supplied by the motor to the shaft. Also, if electric motor has 45% efficiency, calculate the magnitude (in kJ) and identify the direction (into/out of piston-cylinder) of the shaft work. (3 Marks) (e) Write out 8 analysis/assumption statements to simplify the conservation of mass and energy principles for this unsteady system I U X₂ x² S B $ =▾ ||| = - 1 (3 Marks) (e) Write out 8 analysis/assumption statements to simplify the conservation of mass and energy principles for this unsteady system. EKB1043 (BCHE) CONFIDENTIAL (4 Marks) July, 2021 4/9 (f) Apply the conservation of mass and energy principles, calculate the mass of the R-134a that has entered the piston-cylinder device. (Hint: Unit must be consistent) (10 Marks) QUESTION 3: (20 Marks) For a binary system consist of ortho-xylene (o-xylene) [species 1] and para-xylene (p-xylene) A vertical piston-cylinder device initially contains 12 kg of refrigerant R-134a, 9 kg of which is in the liquid phase. The mass of the stainless-steel piston helps to maintain a constant pressure of 400 kPa inside the piston-cylinder. A stream of R134-a at 0.9 MPa and 90°C is allowed to enter the piston-cylinder from a supply line until all the liquid in the cylinder has vaporized. The piston-cylinder is placed in an air-conditioned room, so there is a heat loss of 4500 J from the system. Furthermore, there is a rotating shaft that attached to the piston- cylinder, which is used to agitate the R-134a for better mixing. W. Electric motor Wsh Shaft Vapor Liquid Valve Control volume Inlet stream is used to agitate the R-134a for better mixing. W. Electric motor Q Wsh Shaft Vapor Liquid Valve Control volume Inlet stream (a) Determine the initial phase and properties (temperature, specific volume, internal energy, enthalpy, and entropy) of the R-134a inside the piston-cylinder. (6 Marks) (b) Determine the final phase and properties (temperature, specific volume, internal energy, enthalpy, and entropy) of the R-134a inside the piston-cylinder. (6 Marks) (c) Identify the phase and properties [quality (determine if applicable), specific volume, 3 mes energy, enthalpy, and entropy) of the R-134a inside the piston-cylinder. (6 Marks) (c) Identify the phase and properties [quality (determine if applicable), specific volume, internal energy, enthalpy, and entropy] of the R-134a in the inlet stream. (6 Marks) (d) The rotating shaft is externally powered by the electric motor, which operated at 200 V and 2.7 A. The electric motor supplies the electric work to the shaft to generate the shaft work. If the influx process of R-134a stream took place for 0.5 h, calculate the electric work supplied by the motor to the shaft. Also, if electric motor has 45% efficiency, calculate the magnitude (in kJ) and identify the direction (into/out of piston-cylinder) of the shaft work. (3 Marks) (e) Write out 8 analysis/assumption statements to simplify the conservation of mass and energy principles for this unsteady system I U X₂ x² S B $ =▾ ||| = - 1 (3 Marks) (e) Write out 8 analysis/assumption statements to simplify the conservation of mass and energy principles for this unsteady system. EKB1043 (BCHE) CONFIDENTIAL (4 Marks) July, 2021 4/9 (f) Apply the conservation of mass and energy principles, calculate the mass of the R-134a that has entered the piston-cylinder device. (Hint: Unit must be consistent) (10 Marks) QUESTION 3: (20 Marks) For a binary system consist of ortho-xylene (o-xylene) [species 1] and para-xylene (p-xylene)

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Solution Given data Refrigerant R134a Solution x m m mv 12 9 m 3 12 mv m ... View the full answer