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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.

08.02 - The Internal Energy Departure Function Click here. 100 2

The Internal Energy Departure Function (11min) (uakron.edu)

Deriving departure functions for a variety of equations of state is simplified by transforming to dimensionless units and using density instead of volume. This also leads to an extra simplification for the internal energy departure function.

Comprehension Questions:

1. What is the value of T(∂P/∂T)V - P for an ideal gas?
2. What is the value of (∂U/∂V)T for an ideal gas and how can you explain this result at the molecular scale?
3. The Redlich-Kwong (RK) EOS is: P=RT/(V-b) -a/(V2RT1.5). Use Eqn. 8.13 to solve for (U-Uig)/RT of the RK EOS.
4. The RK EOS can be written as: Z = 1/(1-) - /(RT1.5). Use Eqn. 8.14 to solve for (U-Uig)/RT of the RK EOS.

11.02 - Calculations with Activity Coefficients Click here. 100 3

Bubble Temperature (2:43) (msu.edu)

The culmination of the activity coefficient method is application of the fitted activity coefficients to extrapolate from limited experiments in a Stage III calculation. The bubble temperature is the easiest after bubble pressure. The recommended order of study is 1) Bubble Pressure; 2) Bubble Temperature; 3) Dew Pressure; 4) Dew Temperature. Note that an entire Txy diagram can be generated with bubble temperature calculations; no dew calculations are required.

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.

Comprehension Questions:
1. How is "expansion-contraction" work related to force times distance?
2. What is the expression for "flow" work? Explain how it relates to force times distance for fluid flowing in a pipe.
3. What expression can we use for calculating "shaft" work, as in a pump or turbine? What is the technique of calculus to which it is related?

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 2:1 ratio to a reactor at 500K and 20 bars with a catalyst that favors only CH3OH as its product. Calculate ΔGRº and ΔHRº.
2. 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 ΔGRº and ΔHRº.
3. 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 ΔGRº and ΔHRº.
4. 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 ΔGTº and ΔHTº. Check your answer for ΔGTº using the value given for Ka in Example 17.1.
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 Ka, ΔGTº and ΔHTº.
6. CH3OH is fed to a reactor at 200ºC and 1 bar with a catalyst that produces CO and H2. Calculate Ka, ΔGTº and ΔHTº for this reaction and compare to the literature values given in Example 17.6 of Section 17.10.
7. CH3OH is fed to a reactor at 300ºC and 1 bar with a catalyst that produces CO and H2. Calculate Ka 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.




07.06 Solving The Cubic EOS for Z Click here. 100 1

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.

Comprehension Questions:

1. Which of the following represents the vapor pressure for argon at 100K?
(a) 3.000 bars (b) 4.000 bars (c) 3.26903 bars.

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.
Comprehension Questions: Assume zero subcooling and superheating in the condenser and evaporator.
1. An OVC operates with 43 C in the condenser and -33 C in the evaporator. Why is the condenser temperature higher than than the evaporator temperature? Shouldn't it be the other way around? Explain.
2. An OVC operates with 43 C in the condenser and -33 C in the evaporator. The operating fluid is R134a. Estimate the pressures in the condenser and evaporator using the table in Appendix E-12.
3. An OVC operates with 43 C in the condenser and -33 C in the evaporator. The operating fluid is R134a. Estimate the pressures in the condenser and evaporator using the chart in Appendix E-12.
4. An OVC operates with 43 C in the condenser and -33 C in the evaporator. The operating fluid is R134a. Estimate the pressures in the condenser and evaporator using Eqn 2.47.
5. An OVC operates with 43 C in the condenser and -33 C in the evaporator. Assume the compressor of the OVC cycle is adiabatic and reversible. What two variables (P,V,T,U,H,S) determine the state at the outlet of the compressor?

08.02 - The Internal Energy Departure Function Click here. 100 1

Departure Function Derivation Principles (8:03) (msu.edu)
This screencast covers sections 8.2 - 8.8. Concepts of using the equation of state to evaluate departure functions. The screencasts also discusses the choice of density integrals or pressure integrals. The use of a reference state is discussed.

13.04 - UNIQUAC Click here. 100 1

Volumes and Areas from Group Contributions (3:04)

Group contributions are used widely in property prediction. The volumes and surface areas have been determined by x-ray data and high-temperature collision data. The UNIQUAC and UNIFAC activity coefficient methods use these quantities to calculation volume fractions and surface area fractions. The assignment of functional groups for a molecule must be done carefully to assure agreement with the groups used by the model developers.

Comprehension Questions:

1. Estimate R and Q for 1,4 dihydroxy benzene.

2. Estimate R and Q for n-propyl alcohol and compare them to the values for IPA.

3. Estimate R and Q for methyl-npropyl ketone.

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?
2. 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 ammonia synthesis process when a reference temperature of 600K is used?

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