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A1 Answer ALL parts (a)-(d) A 30 litre scuba tank initially contains air at 1 bar and a temperature of 300 K. The tank is charged from a high pressure air supply which is at an initial temperature of 280 K until the scuba tank has a final pressure of 350 bar. You may also assume that air is an ideal gas and that Rg = 0.287 kJ/kg/K and y = 1.4, where y is the adiabatic index. (a) Treating this as an unsteady flow problem, determine the change in mass of the tank as well as the final temperature, given that this can be assumed to be an adiabatic process. State all assumptions made. (b) Given that the charging process has an isentropic efficiency (ns = Ahactual/Ahs) of 70%, what would be the final temperature of the tank after charging and use this with the unsteady flow energy equation to estimate the heat lost during this process? (c) The tank is allowed to cool back to 300 K from your answer to part (b) and then discharged adiabatically through a valve to provide air to a diver. We can neglect kinetic and potential energy in this case and assume that ambient pressure is 1 bar. Determine the heat lost during cooling and the flow work done during the discharging process assuming that the final pressure in the tank returns again. What is the final temperature of the discharged gas? (d) From the final temperature of the tank from part (a), discuss how this temperature varies with y, when The final pressure is much higher than the initial pressure. (i) (ii) The temperature of the high pressure line is much higher than the initial temperature in the tank.

A1 Answer ALL parts (a)-(d) A 30 litre scuba tank initially contains air at 1 bar and a temperature of 300 K. The tank is charged from a high pressure air supply which is at an initial temperature of 280 K until the scuba tank has a final pressure of 350 bar. You may also assume that air is an ideal gas and that Rg = 0.287 kJ/kg/K and y = 1.4, where y is the adiabatic index. (a) Treating this as an unsteady flow problem, determine the change in mass of the tank as well as the final temperature, given that this can be assumed to be an adiabatic process. State all assumptions made. (b) Given that the charging process has an isentropic efficiency (ns = Ahactual/Ahs) of 70%, what would be the final temperature of the tank after charging and use this with the unsteady flow energy equation to estimate the heat lost during this process? (c) The tank is allowed to cool back to 300 K from your answer to part (b) and then discharged adiabatically through a valve to provide air to a diver. We can neglect kinetic and potential energy in this case and assume that ambient pressure is 1 bar. Determine the heat lost during cooling and the flow work done during the discharging process assuming that the final pressure in the tank returns again. What is the final temperature of the discharged gas? (d) From the final temperature of the tank from part (a), discuss how this temperature varies with y, when The final pressure is much higher than the initial pressure. (i) (ii) The temperature of the high pressure line is much higher than the initial temperature in the tank.

Elements Of Electromagnetics
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
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A1 Answer ALL parts (a) – (d) A 30 litre scuba tank initially contains air at 1 bar and a temperature of 300 K. The tank is charged from a high pressure air supply which is at an initial temperature of 280 K until the scuba tank has a final pressure of 350 bar. You may also assume that air is an ideal gas and that Rg = 0.287 kJ/kg/K and y = 1.4, where y is the adiabatic index. (a) Treating this as an unsteady flow problem, determine the change in mass of the tank as well as the final temperature, given that this can be assumed to be an adiabatic process. State all assumptions made. (b) Given that the charging process has an isentropic efficiency (n = Ahactual/Ahs) of 70%, what would be the final temperature of the tank after charging and use this with the unsteady flow energy equation to estimate the heat lost during this process? (c) The tank is allowed to cool back to 300 K from your answer to part (b) and then discharged adiabatically through a valve to provide air to a diver. We can neglect kinetic and potential energy in this case and assume that ambient pressure is 1 bar. Determine the heat lost during cooling and the flow work done during the discharging process assuming that the final pressure in the tank returns again. What is the final temperature of the discharged gas? (d) From the final temperature of the tank from part (a), discuss how this temperature varies with y, when The final pressure is much higher than the initial pressure. (i) (ii) The temperature of the high pressure line is much higher than the initial temperature in the tank.
Transcribed Image Text:A1 Answer ALL parts (a) – (d) A 30 litre scuba tank initially contains air at 1 bar and a temperature of 300 K. The tank is charged from a high pressure air supply which is at an initial temperature of 280 K until the scuba tank has a final pressure of 350 bar. You may also assume that air is an ideal gas and that Rg = 0.287 kJ/kg/K and y = 1.4, where y is the adiabatic index. (a) Treating this as an unsteady flow problem, determine the change in mass of the tank as well as the final temperature, given that this can be assumed to be an adiabatic process. State all assumptions made. (b) Given that the charging process has an isentropic efficiency (n = Ahactual/Ahs) of 70%, what would be the final temperature of the tank after charging and use this with the unsteady flow energy equation to estimate the heat lost during this process? (c) The tank is allowed to cool back to 300 K from your answer to part (b) and then discharged adiabatically through a valve to provide air to a diver. We can neglect kinetic and potential energy in this case and assume that ambient pressure is 1 bar. Determine the heat lost during cooling and the flow work done during the discharging process assuming that the final pressure in the tank returns again. What is the final temperature of the discharged gas? (d) From the final temperature of the tank from part (a), discuss how this temperature varies with y, when The final pressure is much higher than the initial pressure. (i) (ii) The temperature of the high pressure line is much higher than the initial temperature in the tank.
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