- #1
bartieshaw
- 50
- 0
Hey.
Im doing this question where Air (said to be ideal gas) is compressed from a pressure of 0.1 MPa and Temp 300K to pressure .5 MPa and temperature 480K. We are supposed to determine whether the process is possible to do adiabatically (sorry if that is the wrong spelling).
I hadnt done a question like this before so i began by assuming it was an adiabatic process. by doing this and using thermodynamic data from Moran and Shapiro (our textbook) i got the work done on the system to be approx. 130 kJ/kg
I then went on to try and use the ideal gas equation to determine the work required for this process (using the definition, work = integral (pressure) dV)
now, to do this i had to make the assumption that for an ideal gas an Adiabatic process is also polytropic (pV^n = const.)
My notes say that polytropic processes do not have to be adiabatic, but it does not describe whether or not adiabatic processes have to be polytropic (my assumption).
My question is,
If a process is adiabatic, does it mean it is also polytropic?
PS.
Using my above method i get a rather nice answer, being that it is not possible, but i do not enjoying making assumptions.
cheers,
bart
Im doing this question where Air (said to be ideal gas) is compressed from a pressure of 0.1 MPa and Temp 300K to pressure .5 MPa and temperature 480K. We are supposed to determine whether the process is possible to do adiabatically (sorry if that is the wrong spelling).
I hadnt done a question like this before so i began by assuming it was an adiabatic process. by doing this and using thermodynamic data from Moran and Shapiro (our textbook) i got the work done on the system to be approx. 130 kJ/kg
I then went on to try and use the ideal gas equation to determine the work required for this process (using the definition, work = integral (pressure) dV)
now, to do this i had to make the assumption that for an ideal gas an Adiabatic process is also polytropic (pV^n = const.)
My notes say that polytropic processes do not have to be adiabatic, but it does not describe whether or not adiabatic processes have to be polytropic (my assumption).
My question is,
If a process is adiabatic, does it mean it is also polytropic?
PS.
Using my above method i get a rather nice answer, being that it is not possible, but i do not enjoying making assumptions.
cheers,
bart