Review Sheet for Applied Thermodynamics | MAE 321, Study notes of Thermodynamics

Download Review Sheet for Applied Thermodynamics | MAE 321 and more Study notes Thermodynamics in PDF only on Docsity! MAE 321 – Applied Thermodynamics Extra Credit April 11, 2009 The extra credit is due Wednesday April 15, 2009. Each problem is worth the points indicated. I encourage you to work in small groups to learn this material. However, copying of the solution from another is not acceptable. 1. Explain the importance of Chapter 12. (10 points) 2. Starting with the Maxwell relationships, estimate the change in entropy of 1 kg of R134a at a temperature of 120 °C when the pressure changes from 1.0 to 1.2 MPa. Compare this value with the one obtained by using the entropy values in the R134a table located in the appendix. (25 points) 3. Explain the importance of Chapter 13. (10 points) 4. Air consists of approximately 21% oxygen, 78% nitrogen, <1% argon, and ~400 ppm carbon dioxide on a molar basis. Determine (a) the mole fraction, (b) mass fraction, and (c) molar mass of air. (25 points) 5. Design a simple experiment to prove (a) Dalton’s law of additive pressures and (b) Amagat’s law of additive volumes. (15 points) 6. Under what condition(s) is (are) the mole fraction, pressure fraction, and volume fraction of an ideal gas the same? (15 points) Suggested Book Problems to Review: These problems will not be collected, but are suggested as a review. Chapter 12: 2, 6, 9, 16, 20, 21, 24, 35, 56, 63, 70, 73 Chapter 13: 4, 6, 8, 12, 17, 18, 19, 24, 49, 50, 51 MAE 321 – Applied Thermodynamics Extra Credit April 11, 2009 The extra credit is due Wednesday April 15, 2009. Each problem is worth the points indicated. I encourage you to work in small groups to learn this material. However, copying of the solution from another is not acceptable. 1. Explain the importance of Chapter 12. (10 points) Chapter 12 covers thermodynamic properties and relations to determine thermodynamic properties. This chapter develops the relationships necessary to calculate unknown properties (u, h, and s) based on properties that are known or that can be measured (P, T, m, and v). The methods discussed in chapter 12 were used to develop the property tables in the appendix. 3. Explain the importance of Chapter 13. (10 points) Chapter 13 is an extension of chapter 12 in that it covers thermodynamic properties and relations to determine thermodynamic properties. Whereas chapter 12 covered the general relations, this chapter is only for gas mixtures. Specifically, chapter 13 covers non-reacting gas mixture properties. Note that chapter 15 and 16 cover reacting systems and that we will only touch on reacting mixtures in chapter 15 when discussing combustion. The methods discussed in chapter 13 allow us to look at how real or ideal gases interact with each other. 5. Design a simple experiment to prove (a) Dalton’s law of additive pressures and (b) Amagat’s law of additive volumes. (15 points) (a) Dalton’s law states that the pressure of a gas mixture is equal to the sum of the pressures each gas would exert if it existed alone at the mixture temperature and volume. An example would be two containers (A and B), with equal volume (1 liter), contain a gas (air) at the same temperature (20 °C). The gas in one container is transferred to the other container in an isothermal manner so that gases A and B are contained in one of the containers at the same initial temperature. (b) Amagat’s law states that the volume of a gas mixture is equal to the sum of the volumes each gas would exert if it existed alone at the mixture temperature and pressure. An example would be two containers (A and B), with equal pressure (1 atm), contain a gas (air) at the same temperature (20 °C). The two containers are then combined (through an infinitely small valve) so that the gases mix (interact) with each other at the same pressure and temperature. 6. Under what condition(s) is (are) the mole fraction, pressure fraction, and volume fraction of an ideal gas the same? (15 points) For ideal gases, the mole, pressure, and volume fractions are the same. See page 705 and equation 13-8. This is important since many concentrations are given in percent (%), parts per million (ppm), molar basis (μmol/mol), or partial pressure and that these units are equivalent (if the ideal gas assumption is used). They only differ on unit conversion 1.0 partial pressure fraction =100%=1,000,000 ppm. For instance, you can purchase standard reference material from NIST at: https://www-s.nist.gov/srmors/tables/view_table.cfm?table=107-1.htm The first item on this page is SRM 1674b, a 7% mol/mol CO2 bottle or 7% CO2 by volume. The remaining 93% is nitrogen (N2). The partial pressure of the CO2 is 0.07 and N2 is 0.93. 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