Argon gas enters an adiabatic turbine at 900 kPa and 450oC with a velocity of 80 m/s and leaves at 150 kPa and a velocity of 150 m/s. The inlet cross-sectional area is 60 cm2. If the power output of the turbine is 250 kW, determine the exit temperature of the argon. The process operates at steady-state and argon behaves as an ideal gas.
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4 comments:
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HINTS:
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* Check out the comments from Dr. B's course! There are some good nuggets in there that can help you solve the problem.
* You can assume a constant specific heat. You can get the values for Cp and Cv from the NIST Webbook or the FE Handbook pg 83.
* To calculate the mass flow rate, use the definition! You can calculate the specific volume from the ideal gas law. Be sure to be careful with your units!
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ANSWERS:
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V1specific: 0.16722 m^3/kg
T2 = 267.14 C
Direct FE Handbook link
When you are using the equation first law of thermodynamics and are using -Wdot=mdot(dH +dEkinetic) i keep having unit issues. When i try to solve for dH. I keep getting somethign one side of my equatino being j/g= dH + something in m/s.
Can anyone tell me where I am going wrong?
Anonymous 1:24 PM:
I think the problem is in the Ekin term. Specific Ekin = v^2/(2*gc). So, the units are: Ekin[=] (m/s)^2 / (kg*m/(N*s^2))
So:
Ekin[=](m^2/s^2)*(N*s^2/(kg*m))
Ekin[=]N*m/kg
Ekin[=]J/kg
Be sure to divide this by 1000 J/kJ before adding it to specific H !
Also, note that there is no shaft work in a nozzle !
Best of luck !
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