

HW #4, P11.28 - Excess Gibbs Free Energy of a Real.HW #4, P10.31+ - Equilibrium Flash Distillation U.

HW #4, P10.25+ - Bubble and Dew Point Calculation.HW #4, P11.25 - Fugacity of a Mixture: Real vs.HW #5, P12.27 - Volume Change of Mixing Two Liquid.HW #5, P12.22 - Multicomponent Flash Using the Wil.HW #5, WB.4 - Bubble Point and Dew Point Calculati.HW #5, WB.3 - Determination of Azeotropes Using th.HW #5, WB.2 - Determination of Azeotropes Using M.HW #5, WB.1 - Pxy Diagram and Henry's Law Constant.HW #5, P12.3 - Fitting VLE Data Using the Margules.But I only got to something like 4e-4 in one try. You can also run solver on each eqn, one at a time and then go back and do all 5 together. I you want, you can go onto the options tab and change the Estimates, Derivatives and Search methods. That should get you very close to the right answer in one pass in Solver. Constrain both Zs to be > 0.04 AND constrain BOTH f'(Z) functions to be > 0 (to make sure the two roots you find are the sat vap and sat liq roots and not the meaningless one). The easiest way to get Solver to go where you want it is to add FOUR constraints. This is something like the %RMS error for the 5 eqns. I minimized SQRT of the sum of these 5 error terms (divided by 5. Right ? I used %error^2 for each equilibrium eqn and f(Z)^2 for the SRK eqns. You should also have 5 unks: Zvap, Zliq, P, x1 and x2. any suggestions." I replied: OK, you have 5 eqns: 3 of the them are yliq The remaining 2 eqns are SRK eqns: one for liquid and one for vapor. I set a constraint for solver that Z is greater than B, but it won't listen. I get num! I think this is because Zliq is below Bliq and the same for vapor. A student emailed me the following question: "I have all my 5 equations set up and am trying to simultaneously solve for the unknowns.
