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Maximum Power Output of a Turbine

Hi,
I need with the following question.

Argon gas expands in an adiabatic turbine from 3MPa and 750 C to .2 MPa at a rate of 5 kg/s. Neglect KE and PE effects. Find maximum power output.

I know I need to first find the temperature of state two and then use that to solve for h2 (I have already solved for h1) then plug it in to W=mass flow rate(h1-h2) to solve for the work and go from there but I am having a problem finding T2. Any help would greatly be appreciated.
 

Answers and Replies

82
0
Welcome thermohelp12,

I think you need to make the assumption that the turbine is isentropic.

P.S. There is a HW help section of the forums.
 
Hi,
I need with the following question.

Argon gas expands in an adiabatic turbine from 3MPa and 750 C to .2 MPa at a rate of 5 kg/s. Neglect KE and PE effects. Find maximum power output.

I know I need to first find the temperature of state two and then use that to solve for h2 (I have already solved for h1) then plug it in to W=mass flow rate(h1-h2) to solve for the work and go from there but I am having a problem finding T2. Any help would greatly be appreciated.
I think h2oski1326 was right you need to consider the isentropic process because according to your problem the gas expands in adiabatic process, that means you have a closed sytem, and if the system is closed there is no cahange in temperature. you can solved h2 using temperature from h1.
 
stewartcs
Science Advisor
2,177
3
I think h2oski1326 was right you need to consider the isentropic process because according to your problem the gas expands in adiabatic process, that means you have a closed sytem, and if the system is closed there is no cahange in temperature. you can solved h2 using temperature from h1.
Turbines are open systems (i.e. control volumes).

A closed system does not necessarily mean that there is not a temperature change. An adiabatic system means that no heat is transferred across the system boundary. This is a common assumption (in homework problems) with turbines since they are normally well insulated.

BTW, this thread is 5 months old.

CS
 

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