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Friday, April 14, 2006
HW #7 - P #7 - Maximum Work output from an Adiabatic Turbine - 5 pts
Steam enters an adiabatic turbine at 800 psia and 900°F and leaves at a pressure of 40 psia. Determine the maximum amount of work that can be delivered by this turbine.
6 comments:
Anonymous
said...
Assuming deltaKE,PE, and Q are all zero, then first law reduces to W=-delta(internal energy) Adiabatic reversible means isentropic, so knowing the first states entropy allows us to fix the second state,find the quality, and find Uhat at both states. This isn't giving me the right answer though.
Alias 6:56 PM Because the turbine is an open system, it will be much easier to use the form of the 1st Law for open systems, in this case, Wsh,dot = -mdot * deltaHhat.
Your approach to using the fact that the turbine isnetropic is correct. You will get the right answer now.
Katie 8:20 PM W_hat = W_dot / m_dot. Although we cannot determine either W_dot or m_dot, we can determine W-hat ( the shaft work per kg of flowing fluid).
Im missing something little here... i used the superheated tables to get S and then the sat tables to find x and H.... wow just typing that helped me figure it out
6 comments:
Assuming deltaKE,PE, and Q are all zero, then first law reduces to W=-delta(internal energy) Adiabatic reversible means isentropic, so knowing the first states entropy allows us to fix the second state,find the quality, and find Uhat at both states. This isn't giving me the right answer though.
Alias 6:56 PM
Because the turbine is an open system, it will be much easier to use the form of the 1st Law for open systems, in this case, Wsh,dot = -mdot * deltaHhat.
Your approach to using the fact that the turbine isnetropic is correct. You will get the right answer now.
How do we know what mdot is though?
Katie 8:20 PM
W_hat = W_dot / m_dot.
Although we cannot determine either W_dot or m_dot, we can determine W-hat ( the shaft work per kg of flowing fluid).
Im missing something little here... i used the superheated tables to get S and then the sat tables to find x and H.... wow just typing that helped me figure it out
nikfoo 10:53 PM
So, you don't have a question anymore.
Good work.
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