CHAPTER 6 Entropy

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-1 The system considered in the development of the Clausius inequality. 6-1

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-5 A cycle composed of a reversible and an irreversible process. 6-2

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-6 The entropy change of an isolated system is the sum of the entropy changes of its components, and is never less than zero. 6-3

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-10 The entropy of a pure substance is determined from the tables (like other properties). 6-4

FIGURE 6-11 Schematic of the T-s diagram for water. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-11 Schematic of the T-s diagram for water. 6-5

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-16 On a T-S diagram, the area under the process curve represents the heat transfer for internally reversible processes. 6-6

FIGURE 6-19 The T-S diagram of a Carnot cycle (Example 6–6). Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-19 The T-S diagram of a Carnot cycle (Example 6–6). 6-7

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-36 The isentropic relations of ideal gases are valid for the isentropic processes of ideal gases only. 6-8

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-37 The use of Pr data for calculating the final temperature during an isentropic process. 6-9

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-39 The use of vr data for calculating the final temperature during an isentropic process (Example 6–10). 6-10

FIGURE 6-43 Schematic and T-s diagram for Example 6–12. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-43 Schematic and T-s diagram for Example 6–12. 6-11

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-45 P-v diagrams of isentropic, polytropic, and isothermal compression processes between the same pressure limits. 6-12

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-46 P-v and T-s diagrams for a two-stage steady-flow compression process. 6-13

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-49 The h-s diagram for the actual and isentropic processes of an adiabatic turbine. 6-14

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-51 The h-s diagram of the actual and isentropic processes of an adiabatic compressor. 6-15

FIGURE 6-53 Schematic and T-s diagram for Example 6–15. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-53 Schematic and T-s diagram for Example 6–15. 6-16

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-54 The h-s diagram of the actual and isentropic processes of an adiabatic nozzle. 6-17

FIGURE 6-61 Mechanisms of entropy transfer for a general system. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-61 Mechanisms of entropy transfer for a general system. 6-18

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-70 Graphical representation of entropy generation during a heat transfer process through a finite temperature difference. 6-19

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-76 The electrical energy consumed by a motor is inversely proportional to its efficiency. 6-20

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. FIGURE 6-77 The efficiency of an electric motor decreases at part load. 6-21