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Lecture 6 – Entropy Nick DiFilippo
Review of Last Class• Entropy• Ways to find Entropy• Entropy Change• Incompressible• Ideal Gas• Tables
• Reversible Process
Entropy Balance Closed System
Developing Entropy balance for a Closed System
Energy Balance Interpretation• Entropy Transfer• Entropy Production
Example 6.2
Closed System Entropy Rate Balance
Closed System Entropy Rate Balance
Gearbox Example
Increase of Entropy Principle• Entropy change of a system can be negative during a process, but entropy
generation cannot be. • Processes occur only in such a direction that the total entropy of the system
plus surroundings increases
Entropy Balance for Control Volumes
Rate Balances for Control Volumes at Steady State
(4.18)
(4.6)
(6.36)
Isentropic Process• Constant Entropy• Ideal Gas Model
Isentropic Process Constant Specific Heat
Isentropic Efficiencies of Industrial Devices• Turbines
Work per unit Mass
Nozzle
(neglect )
Compressors and Pumps
Internally Reversible, Steady State Flow Processes
Work in a Polytropic Process
Ideal Gas
