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|09.10 - Saturation Conditions from an Equation of State||Click here.||60||1||
We can combine the definition of fugacity in terms of the Gibbs Energy Departure Function with the procedure of visualizing an equation of state to visualize the fugacity as characterized by the PR EOS. (21min, uakron.edu) This amounts to plotting Z vs. density, similar to visualizing the vdW EOS. Then we simply type in the departure function formula. Since the PR EOS describes both vapors and liquids, we can calculate fugacity for both gases and liquids. Taking the reciprocal of the dimensionless density ( V/b=1/(bρ) ) gives a dimensionless volume. When the dimensionless pressure (bP/RT) is plotted vs. the dimensionless volume, the equal area rule indicates the pressure where equilibrium occurs and this can be checked by comparing the ln(f/P) values for the liquid and vapor roots. When the pressure is not exactly saturated, we may still be in the 3-root region. Then you need to check the fugacity to determine which phase is stable.
1. What equation can we use to estimate the fugacity of a compressed liquid relative to its saturation value?
|03.1 - Heat Engines and Heat Pumps: The Carnot Cycle||Click here.||60||2||
Heat Engine Introduction (LearnChemE.com, 6min) introduction to Carnot heat engine and Rankine cycle. The Carnot cycle is an idealized conceptual process in the sense that it provides the maximum possible fractional conversion of heat into work (aka. thermal efficiency, ηθ). But it is impractical for several reasons as discussed in the video. When operating on steam as the working fluid, as is common in nuclear power plants, coal fired power plants, and concentrated solar power plants, the Rankine cycle is much more practical, as explained here. This LearnChemE video is short and sweet, but it applies the property of entropy, which is not introduced until Chapter 4. All you need to know about entropy at this stage is that the change in entropy is zero for an adiabatic and reversible process and the change in entropy is greater than zero when you add heat or cause irreversibility. Since entropy is a state function, we can use the steam tables to facilitate accounting for inefficiencies. Entropy becomes essential when using steam as the working fluid because working out ∫PdV of steam is much more difficult than for an ideal gas. We reiterate this video in Chapter 5, where we discuss calculations for several practical cyclic processes.
|07.06 Solving The Cubic EOS for Z||Click here.||60||4||
5. Peng Robinson Using Solver for PVT and Vapor Pressure - Excel (4:42) (msu.edu)
Describes use of the Goal Seek and Solver tools for Peng-Robinson PVT properties and vapor pressure.
1. Which of the following represents the vapor pressure for argon at 100K?
|11.02 - Calculations with Activity Coefficients||Click here.||60||2||
This example shows how to predict activity coefficients in Excel using the Margules Acid-Base (MAB) model.(8min, uakron.edu) Sometimes you just need a quick estimate of whether to suspect an azeotrope or LLE or some other anomalous behavior. If the MAB model indicates a possible problem, it's time to go to the library or the lab and validate your model with experimental data.
Note: This is a companion file in a series. You may wish to choose your own order for viewing them. For example, you should implement the first three videos before implementing this one. Also, you might like to see how to quickly visualize the Txy analog of the Pxy phase diagram. If you see a phase diagram like the ones in section 11.8, you might want to learn about LLE phase diagrams. The links on the software tutorial present a summary of the techniques to be implemented throughout Unit3 in a quick access format that is more compact than what is presented elsewhere. Some students may find it helpful to refer to this compact list when they find themselves "not being able to find the forest because of all the trees."
|07.06 Solving The Cubic EOS for Z||Click here.||60||4||
2. Solving the PR EOS for Z . (learncheme.com, 5min) Shows how to copy/paste from "Crit.Props" and "IG Cps" to "Props". Then compute some properties. Note: this video incorrectly uses a simple copy/paste instead of "paste special." Therefore, the color of the values on the "Props" tab changes from blue to black. Blue values should indicate values that you can change and black values should indicate cells that you should not alter. If you are having trouble finding a particular compound in the database, try searching for a piece of the name. e.g. if the compound is "nitrous oxide," search for "nitro."
1. What is the value for Zc of nitrous oxide? What is its "abbreviated name?"
2. What is the value of Tc for R1234yf?
3. Estimate the entropy of vaporization of toluene at 383.4K according to the Peng-Robinson EOS.
4. Estimate the entropy of vaporization of ethanol at 0.1MPa according to the Peng-Robinson EOS. Compare to the value you infer from Appendix E.
|01.5 Real Fluids and Tabulated Properties||Click here.||60||2||
Steam Tables (LearnChemE.com) (5:59) calculate enthalpy of steam by interpolation
|01.2 Molecular Nature of Temperature, Pressure, and Energy||Click here.||60||9||
Molecular Nature of Internal Energy: Configurational Energy. (uakron.edu, 19min) Making the connection between "u" and "U" requires the concept configuring the molecules such that their potentials overlap. Then it is a simple matter (conceptually) to count the number of overlaps that occur and multiply by the energy of the overlap to get the "configurational energy." Adding the configurational energy to the translational (and vibrational) energy (Uig, discussed above), gives the total "U."
For 1-4, assume 100 molecules are held in a cylinder with solid walls. A piston in the cylinder can move to adjust the density.
|10.03 - Binary VLE using Raoult's Law||Click here.||60||2||
Raoult's Law (5:39) (msu.edu)
|03.6 - Energy Balance for Reacting Systems||Click here.||60||1||
Heat Removal from a Chemical Reactor (uakron, 8min) determines heat removal so that a chemical reactor is isothermal following the pathway of Figure 3.5b using the pathway of Figure 2.6c if a heat of vaporization is involved. The reaction is: N2 + 3H2 = 2NH3 at 350C and 1 bar. The pathway to go from products to the reference condition is to correct for any liquid formation at the conditions of the product stream then cool/heat the products to 25C (the reference temperature), then "unreact" them back to their elements of formation. Summing up the enthalpy changes over these steps gives the overall enthalpy of the reactor outlet stream. The same procedure applied to the reactor inlet gives the overall enthalpy of reactor inlet stream. Then the heat duty of the reactor is simply the difference between the two stream enthalpies.
|11.13 - Osmotic Pressure||Click here.||60||5||
Osmotic Pressure (7:23) (Learncheme.com)
A derivation of the relation for osmotic pressure, and an explanation of why the pressures are different on each side of the semi-permeable membrane.