# 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 | 1 |
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. |

10.02 - Vapor-Liquid Equilibrium (VLE) Calculations | Click here. | 100 | 2 |
VLE Routines - General Strategies (4:49) (msu.edu) Deciding which routine to use is more challenging than it appears. Also understanding the strategy used to solve the problems is extremely helpful in being able to develop the equations to solve instead of trying to memorize them. |

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.) |

04.09 Turbine calculations | Click here. | 100 | 2 |
Entropy Balances: Solving for Turbine Efficiency Sample Calculation. (uakron.edu, 10min) Steam turbines are very common in power generation cycles. Knowing how to compute the actual work, reversible work, and compare them is an elementary part of any engineering thermodynamics course. Comprehension Questions: 1. An adiabatic turbine is supplied with steam at 2.0 MPa and 600°C and it exhausts at 98% quality and 24°C. (a) Compute the work output per kg of steam.(b) Compute the efficiency of the turbine. 2. A Rankine cycle operates on steam exiting the boiler at 7 MPa and 550°C and expanding to 60°C and 98% quality. Compute the efficiency of the turbine. |

02.01 Expansion/Contraction Work | Click here. | 100 | 2 |
Vocabulary in Sections 2.1-2.3: Forms of "Work." (uakron.edu, 11 min) Making cookies is hard work. In discussing work, we develop several shorthand terms to refer to specific common situations: expansion-contraction work, shaft work, flow work, stirring work, "lost" work. These terms comprise the headings of sections 2.1-2.3, but it is convenient to discuss them all at once. The important thing to remember is that work is really just force times distance, pure and simple. The shorthand terms are not intended to complicate the discussion, but to expedite the analysis of the energy balance. Developing some familiarity with the terms related to common daily experiences may help you to assimilate this new vocabulary. Sample calculations (13min) illustrate a remarkable difference when one is faced with gas compression vs. liquid pump work. Comprehension Questions: |

01.5 Real Fluids and Tabulated Properties | Click here. | 100 | 2 |
Double interpolation (uakron, 8min) is exactly what it sounds like: to find a steam property when neither the pressure nor temperature are among the tabulated values, you need to interpolate twice. We interpolate first on pressure, then on temperature. It is a bit tedious, but straightforward. Comprehension Questions: |

17.05 - Effect of Pressure, Inerts, Feed Ratios | Click here. | 100 | 1 |
How to push, pull, persuade a reaction (3:32) (msu.edu) Pressure can be used to influence conversion for reactions where gas phase species are present. Feed ratios, inerts, or simultaneous reactions can also be used. Comprehension Questions: 1. The principle by which a change in temperature, pressure, or concentration leads to a counteracting change in equilibrium is known as:_____. |

08.07 - Implementation of Departure Functions | Click here. | 100 | 1 |
Helmholtz Departure - PR EOS (uakron.edu, 11min) This lesson focuses first and foremost on deriving the Helmholtz departure function. It illustrates the application of integral tables from Apx. B and the importance of applying the limits of integration. It is the essential starting point for deriving properties involving entropy (S,A,G) of the PREOS, and it is a convenient starting point for deriving energetic properties (U,H). |

07.02 Corresponding States | Click here. | 100 | 1 |
Principles of Corresponding States (10:02) (msu.edu) Comprehension Questions: 1. What is the value of the reduced vapor pressure for Krypton at a reduced temperature of 0.7? How does this help us to characterize the vapor pressure curve? 2. Sketch the graph of vapor pressure vs. temperature as presented in this screencast for the compounds: Krypton and Ethanol. Be sure to label your axes completely and accurately. Draw a vertical line to indicate the condition that defines the acentric factor. |

05.4 - Refrigeration | Click here. | 100 | 2 |
Refrigeration Cycle Introduction (LearnChemE.com, 3min) explains each step in an ordinary vapor compression (OVC) refrigeration cycle and the energy balance for the step. You might also enjoy the more classical introduction (USAF, 11min) representing your tax dollars at work. The musical introduction is quite impressive and several common misconceptions are addressed near the end of the video. |