# Top-rated ScreenCasts

Text Section | Link to original post | Rating (out of 100) | Number of votes | Copy of rated post |
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08.07 - Implementation of Departure Functions | Click here. | 100 | 2 |
Derive the internal energy departure function (uakron.edu, 20min) for the following EOS: Comprehension: Given ( /_{TV}RT = -2ln(1-η) - 16.49_{P}η/[1-_{P}βεβε(1-2η)/(1+2_{P}η)^2 ]_{P}1. Derive the internal energy departure function. 2. Derive the expression for the compressibility factor. 3. Solve the EOS for Zc. |

05.2 - The Rankine cycle | Click here. | 100 | 1 |
Rankine Cycle Introduction (LearnChemE.com, 4min) The Carnot cycle becomes impractical for common large scale application, primarily because H2O is the most convenient working fluid for such a process. When working with H2O, an isentropic turbine could easily take you from a superheated region to a low quality steam condition, essentially forming large rain drops. To understand how this might be undesirable, imagine yourself riding through a heavy rain storm at 60 mph with your head outside the window. Now imagine doing it 24/7/365 for 10 years; that's how long a high-precision, maximally efficient turbine should operate to recover its price of investment. Next you might ask why not use a different working fluid that does not condense, like air or CO2. The main problem is that the heat transfer coefficients of gases like these are about 40 times smaller that those for boiling and condensing H2O. That means that the heat exchangers would need to be roughly 40 times larger. As it is now, the cooling tower of a nuclear power plant is the main thing that you see on the horizon when approaching from far away. If that heat exchanger was 40 times larger... that would be large. And then we would need a similar one for the nuclear core. Power cycles based on heating gases do exist, but they are for relatively small power generators. |

14.10 Solid-liquid Equilibria | Click here. | 100 | 3 |
Solid-liquid Equilibria using Excel (7:38min, msu) The strategy for solving SLE is discussed and an example generating a couple points from Figure 14.12 of the text are performed. Most of the concepts are not unique to UNIFAC or Excel. This screeencast shows how to use the solver tool to find solubility at at given temperature. |

07.06 Solving The Cubic EOS for Z | Click here. | 100 | 2 |
6. Solving for density (uakron.edu, 9min) An alternative to solving directly for Comprehension Questions: 1. Solve for the liquid density (mol/cm3) of n-pentane at 62C and 2.5 bars using the vdW EOS. |

08.02 - The Internal Energy Departure Function | Click here. | 100 | 1 |
Departure Function Derivation Principles (8:03) (msu.edu) |

08.08 - Reference States | Click here. | 100 | 1 |
Peng-Robinson Properties - Excel (6:56) (msu.edu) Provides an overview of using the Peng-Robinson spreadsheet Preos.xlsx for calculation of H, U, S and use of solver. Comprehension Questions: 1. For liquid propane at 298K and 1 MPa, and a reference state of 298K and 1bar propane vapor, what is the ideal gas contribution to "H-H |

17.07 - Temperature Dependence of Ka | Click here. | 100 | 2 |
Example 17.4 and 17.5 solved using Kcalc.xlsx (6:01) (msu.edu) The full form of the temperature dependence of Ka is implemented in Kcalc.xlsx and Kcalc.m. This screecast covers the use of Kcalc.xlsx for Example 17.4 and Example 17.5 of the textbook. Comprehension Questions: 1. CO and H2 are fed in a H. _{R}º2. CO and H2 are fed in a 1:1 ratio to a reactor at 500K and 20 bars with a catalyst that favors only CH3OH as its product. Calculate ΔG and Δ_{R}ºH._{R}º3. CO and H2 are fed in a 1:1 ratio to a reactor at 600K and 20 bars with a catalyst that favors only CH3OH as its product. Calculate ΔG and Δ_{R}ºH._{R}º4. CO and H2 are fed in a 1:1 ratio to a reactor at 500K and 20 bars with a catalyst that favors only CH3OH as its product. Calculate ΔG and Δ_{T}ºH. Check your answer for Δ_{T}ºGusing the value given for _{T}º Kin Example 17.1._{a }5. CO and H2 are fed in a 1:1 ratio to a reactor at 600K and 10 bars with a catalyst that favors only CH3OH as its product. Calculate K, Δ_{a}G and Δ_{T}ºH. _{T}º6. CH3OH is fed to a reactor at 200 ºC and 1 bar with a catalyst that produces CO and H2. Calculate K, Δ_{a}G and Δ_{T}ºH for this reaction and compare to the literature values given in Example 17.6 of Section 17.10._{T}º7. CH3OH is fed to a reactor at 300 ºC and 1 bar with a catalyst that produces CO and H2. Calculate K for this reaction and compare to the value given in Example 17.6 of Section 17.10. Give two reasons why the two estimates are not identical._{a} |

05.2 - The Rankine cycle | Click here. | 100 | 1 |
Thermal Efficiency with a 1-Stage Rankine Cycle. (uakron.edu, 12min) Steam from a boiler enters a turbine at 350C and 1.2MPa and exits at 0.01MPa and saturated vapor; compute the thermal efficiency ( η.) This kind of calculation is one of the elementary skills that should come out of any thermodynamics course. Try to pause the video often and work out the answer on your own whenever you think you can. You will learn much more about the kinds of mistakes you might make if you take your best shot, then use the video to check yourself. Then practice some more by picking out other boiler and condenser conditions and turbine efficiencies. FYI: the conditions of this problem should look familiar because they are the same as the turbine efficiency example in Chapter 4. That should make it easy for you to take your best shot._{E}Comprehension Questions: 1. The entropy balance is cited in this video, but never comes into play. Why not? 2. Steam from a boiler enters a turbine at 400C and 2.5 MPa and exits a 100% efficient turbine at 0.025MPa; compute the Rankine efficiency. Comment on the practicality of this process. (Hint: review Chapter 4 if you need help with turbine efficiency.) |

17.07 - Temperature Dependence of Ka | Click here. | 100 | 2 |
You can customize Kcalc.xlsx (uakron.edu, 17min) to facilitate whatever calculations you may need to perform. This presentation shows how to implement VLOOKUP to automatically load the relevant Hf, Gf, and Cp values. It also shows how to automatically use the Cp/R value when a,b,c,d values for Cp are not available. Finally, it shows how a fairly general table of inlet flows, temperatures, and pressures can be used to set up the equilibrium conversion calculation. The initial set up is demonstrated for the dimethyl ether process, then revised to initiate solution of Example 17.9 for ammonia synthesis. Comprehension Questions: 1. The video shows how the shortcut Van't Hof equation can be written as lnKa=A+B/T. What are the values of A and B for the dimethyl ether process when a reference temperature of 633K is used? |

08.08 - Reference States | Click here. | 100 | 1 |
This sample calculation shows how to compute the liquefaction in the Linde process for methane as the operating fluid. (uakron, 8min) The Linde process is a slight variation on the OVC cycle wherein the liquefied fraction exiting the throttle is captured as product and removed from the process. There is also heat integration in the sense that the cold vapor is used to precool the feed to the throttle. FYI: Since natural gas is mostly methane, this process could be easily adapted to the production of liquefied natural gas (LNG) or liquified petroleum gas (LPG, mostly propane). Liquefied gases may seem impractical when you first encounter them, but they are more efficient for transport because they are so much more dense than the gases. Keeping them as liquids is basically a reflection of the effectiveness of the insulation. If any gas leaks from the relief valve (~1.1 bar), then liquid must evaporate to fill the space. The requisite heat of vaporization in that case cools the remaining below the boiling temperature. No heat = no vaporization. |