Download Properties of Pure Substances in Thermodynamics 1 (MPE 101) and more Assignments Thermodynamics in PDF only on Docsity! Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 3: PROPERTIES OF PURE SUBSTANCES 1. Is it true that water boils at higher temperatures at higher pressures? Explain. Yes. The saturation temperature of a pure substance depends on pressure. The higher the pressure, the higher the saturation or boiling temperature. 2. What is the difference between the critical point and the triple point? At critical point the saturated liquid and the saturated vapor states are identical. At triple point the three phases of a pure substance coexist in equilibrium. 3. Does the amount of heat absorbed as 1 kg of saturated liquid water boils at 10oC have to be equal to the amount of heat released as 1 kg of saturated water vapor condenses at 100oC? Yes. Otherwise, we can create energy by alternately vaporizing and condensing a substance. 4. What is quality? Does it have any meaning in the superheated vapor region? Quality is the fraction of vapor in a saturated liquid-vapor mixture. It has no meaning in the superheated vapor region. 5. Complete this table for water: 6. Complete this table for H2O: Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 3: PROPERTIES OF PURE SUBSTANCES 7. Complete this table for H2O: 8. Refrigerant-134a at 200 kPa and 25oC flows through a refrigeration line. Determine its specific volume. 9. A 1.8-m3 rigid tank contains steam at 220oC. One-third of the volume is in the liquid phase and the rest is in the vapor form. Determine (a) the pressure of the steam, (b) the quality of the saturated mixture, and (c) the density of the mixture. Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 3: PROPERTIES OF PURE SUBSTANCES 13. A piston–cylinder device contains 0.6 kg of steam at 200°C and 0.5 MPa. Steam is cooled at constant pressure until one-half of the mass condenses. (a) Show the process on a T-v diagram. (b) Find the final temperature. (c) Determine the volume change. Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 3: PROPERTIES OF PURE SUBSTANCES 14. Water initially at 200 kPa and 300oC is contained in a piston-cylinder device fitted with stops. The water is allowed to cool at constant pressure until it exists as a saturated vapor and the piston rests on the stops. Then the water continues to cool until the pressure is 100 kPa. On the T-v diagrams sketch, with respect to the saturation lines, the process curves passing through both the initial, intermediate, and final states of the water. Label the T, P and v values for end states on the process curves. Find the overall change in internal energy between the initial and final states per unit mass of water. 15. 10-kg of R-134a at 300 kPa fills a rigid container whose volume is 14 L. Determine the temperature and total enthalpy in the container. The container is now heated until the pressure is 600 kPa. Determine the temperature and total enthalpy when the heating is completed. Faculty of Engineering Thermodynamics 1 Course code: MPE 101 Sheet 3: PROPERTIES OF PURE SUBSTANCES 16. How are the reduced pressure and reduced temperature defined? Reduced pressure is the pressure normalized with respect to the critical pressure; and reduced temperature is the temperature normalized with respect to the critical temperature. 17. Determine the specific volume of refrigerant-134a at 1 MPa and 50oC, using (a) the ideal-gas equation of state and (b) the generalized compressibility chart.
