Cengel ch13

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Cengel ch13

  1. 1. CHAPTER 13Gas – Vapor Mixturesand Air-Conditioning
  2. 2. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-1The Cp of air canbe assumed to beconstant at 1.005kJ/(kg · °C) in thetemperaturerange - 10 to 50°Cwith an errorunder 0.2 percent.13-1
  3. 3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-2At temperatures below50°C, the h = constantlines coincide withthe T = constant lines inthe superheated vaporregion of water.13-2
  4. 4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-4For saturated air, thevapor pressure is equal tothe saturation pressure ofwater.13-3
  5. 5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-5Specific humidity isthe actual amount ofwater vapor in 1 kgof dry air, whereasrelative humidity isthe ratio of theactual amount ofmoisture in the airto the maximumamount of moistureair can hold at thattemperature.13-4
  6. 6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-6The enthalpy ofmoist (atmospheric)air is expressed perunit mass of dry air,not per unit mass ofmoist air.13-5
  7. 7. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-8Constant-pressurecooling of moist airand the dew-pointtemperature on theT-s diagram ofwater.13-6
  8. 8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-11The adiabaticsaturation processand its represen-tation on a T-sdiagram of water.13-7
  9. 9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-12A simple arrangementto measure the wet-bulb temperature.13-8
  10. 10. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-14Schematic for apsychrometric chart.13-9
  11. 11. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-15For saturated air,the dry-bulb, wet-bulb, and dew-pointtemperatures areidentical.13-10
  12. 12. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-20Various air-conditioningprocesses.13-11
  13. 13. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-21During simpleheating, specifichumidity remainsconstant, butrelative humiditydecreases.13-12
  14. 14. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-22During simplecooling, specifichumidity remainsconstant, butrelative humidityincreases.13-13
  15. 15. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-23Heating thehumidification.13-14
  16. 16. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-24Schematic andpsychrometric chartfor Example 13–5.13-15
  17. 17. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-25Schematic andpsychrometric chartfor Example 13–6.13-16
  18. 18. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-27Evaporative cooling.13-17
  19. 19. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-29When two airstreams atstates 1 and 2 are mixedadiabatically, the state ofthe mixture lies on thestraight line connectingthe two states.13-18
  20. 20. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-31An induced-draftcounterflow coolingtower.13-19
  21. 21. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.FIGURE 13-33A spray pond. Photo credit: Yunus Çengel13-20

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