Transient UNSTEADY-FLOW Systems in Thermo in 9 Minutes!

[@LessBoringLectures]

TWO CORRECTIONS: 1) at 6:42 The change in energy is the final energy, E2, MINUS the initial energy, E1. The equation in terms of E1 and E2 is incorrect, but the final value is correct: 3100 kJ/kg. 2) at 7:48 we look for a specific ENTHALPY value of 3100 kJ/kg (h column, not u). The correct P value should be 29.0 MPa, after interpolating.

[@kylecatman7738]

So you look at the "U" column at the end for 3100 kj/kg?? I guess so because 3100 under the enthalpy column at 500 C is like 29 MPa.

[@kylecatman7738]

wrong, for these transient problems, h often equals u.

[@MukeshKumar-xi8ic]

amazing explanation really less boring

[@MoltasElliver]

Can you do an example of a balloon? or when reference states are being used also at around 1:11 in the video. What happend with the mass in the left hand side? (d(mU)/dt). If m is dropped in the left hand side does that affect the mihi term? btw great series

[@MukeshKumar-xi8ic]

Thanks in advance 👍

[@MukeshKumar-xi8ic]

pls add some difficult conceptual problems

[@kylecatman7738]

"h" equals "u" in this equation, so 4 MPa is correct, you really DO look under the internal energy for 3100 kJ/kg at 500C... it can't be 29 MPa my friend that's above the critical pressure for steam which is 22 MPa.

[@kylecatman7738]

Do you look at the comments? I'd like to know if it's 29MPa or 4MPa... see my comments below please.

[@simondemarque2826]

it is not a correct transient computation : to do it correctly (p,t,h,m) with time, you have to account of the flowrate through the nozzle, probably choked at the beginning, then the asymptotic behavior to nil of the flowrate into the insulated vessel