- #1
Red_CCF
- 532
- 0
Hi
I was wondering, for the first law most books have basically Q - W = deltaUsystem + deltaH + deltaKE + deltaPE. Assuming steady state and negligible PE change, we just have deltaH and deltaKE. I was wondering, since H includes flow work (in the form of PV), why is KE still part of the equation? What is the difference between flow work and kinetic energy?
I'm also wondering, with regards to stagnation temperature (http://en.wikipedia.org/wiki/Stagnation_temperature),
If the end state is suppose to be stagnant, why does the derivation result in the balance h0 = h + V^2/2, which implies there's flow in and out at stagnation state? Does this mean that one can have enthalpy/flow work without kinetic energy?
Thanks
I was wondering, for the first law most books have basically Q - W = deltaUsystem + deltaH + deltaKE + deltaPE. Assuming steady state and negligible PE change, we just have deltaH and deltaKE. I was wondering, since H includes flow work (in the form of PV), why is KE still part of the equation? What is the difference between flow work and kinetic energy?
I'm also wondering, with regards to stagnation temperature (http://en.wikipedia.org/wiki/Stagnation_temperature),
If the end state is suppose to be stagnant, why does the derivation result in the balance h0 = h + V^2/2, which implies there's flow in and out at stagnation state? Does this mean that one can have enthalpy/flow work without kinetic energy?
Thanks