A well-insulated piston-cylinder device has 0.89 m ethane gas (R = 0.2765 kJ/kg. K) at 200C...

 

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A well-insulated piston-cylinder device has 0.89 m³ ethane gas (R = 0.2765 kJ/kg. K) at 200°C and 110 kPa. Initially, the piston lies on a set of stops, and the piston is so heavy that a minimum pressure of 178 kPa is required to push it upwards. Inside the piston-cylinder device, the ethane gas is stirred by a fan (work = 42550 J) while being heated by an electric heater (current = 7 A, resistance = 25.22). Upon heating, the ethane gas gains kinetic energy to push piston in an upward direction once the pressure attains 178 kPa; thereafter, ethane expands polytropically until the volume raised to 1.54 m³ and the pressure lowered to 86.46 kPa. The whole electrical heating process consists of 2 subprocesses and 3 thermodynamic states. Assume ethane gas has constant specific heats (cp= 1.7662 kJ/kg . K and c₂ = 1.4897 kJ/kg. K). (Hint: choose your specific heat wisely.) Stop We Ethane Piston Wsh Piston-cylinder device (a) Calculate the intermediate temperature of ethane gas when the pressure attains 178 kPa. (2 Marks) (b) Calculate the polytropic constant and final temperature for the second subprocess. (c) Determine the boundary work for subprocess 1, subprocess 2, and whole process. (d) Write down 4 assumptions that useful to simplify the energy balance. (4 Marks) (e) Calculate the mass of ethane vapor and the heating time for the whole process. (4 Marks) (4 Marks) (6 Marks) A well-insulated piston-cylinder device has 0.89 m³ ethane gas (R = 0.2765 kJ/kg. K) at 200°C and 110 kPa. Initially, the piston lies on a set of stops, and the piston is so heavy that a minimum pressure of 178 kPa is required to push it upwards. Inside the piston-cylinder device, the ethane gas is stirred by a fan (work = 42550 J) while being heated by an electric heater (current = 7 A, resistance = 25.22). Upon heating, the ethane gas gains kinetic energy to push piston in an upward direction once the pressure attains 178 kPa; thereafter, ethane expands polytropically until the volume raised to 1.54 m³ and the pressure lowered to 86.46 kPa. The whole electrical heating process consists of 2 subprocesses and 3 thermodynamic states. Assume ethane gas has constant specific heats (cp= 1.7662 kJ/kg . K and c₂ = 1.4897 kJ/kg. K). (Hint: choose your specific heat wisely.) Stop We Ethane Piston Wsh Piston-cylinder device (a) Calculate the intermediate temperature of ethane gas when the pressure attains 178 kPa. (2 Marks) (b) Calculate the polytropic constant and final temperature for the second subprocess. (c) Determine the boundary work for subprocess 1, subprocess 2, and whole process. (d) Write down 4 assumptions that useful to simplify the energy balance. (4 Marks) (e) Calculate the mass of ethane vapor and the heating time for the whole process. (4 Marks) (4 Marks) (6 Marks)

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Answer a Date Auswend Piston Cyclinden device has R 52765 KJ Kgk T 200C Min pressor 2 1... View the full answer