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Thermodynamic Work

Thermodynamic Work. P M V Subbarao Professor Mechanical Engineering Department I I T Delhi. Development of Power for Different Needs!!!. Displacement Work : Dangerous & Inhuman Technologies. A Need for More General Definition of Work.

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Thermodynamic Work

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  1. Thermodynamic Work P M V Subbarao Professor Mechanical Engineering Department I I T Delhi Development of Power for Different Needs!!!

  2. Displacement Work : Dangerous & Inhuman Technologies

  3. A Need for More General Definition of Work • As an English army officer, Thomas Savery was once ejected from the Lord of the Admiralty's office as a lunatic because he proposed a ship that could be propelled by side-mounted wheels rather than by wind or oars. • He exhibited great fondness for mechanics, and for mathematicians natural philosophy and gave much time to experimenting, to the contriving of various kinds of apparatus, and to invention.

  4. Definition of Thermodynamic Work • Positive work is done by a system, during a given process, when the sole effect external to the system could be reduced to the rise of a weight. • This definition may appear arbitrary. • This is forced on the readers/users to identify all possible work actions in engineering. • Will it consider Mechanical work?

  5. Mechanical Work Generating System

  6. S Mechanical work System Before triggering Surroundings F After triggering

  7. S1 Thermodynamic Work W W Mechanical Work is Thermodynamic work and vice versa. F.S = W*S1

  8. Broader Applications of the Thermodynamic Work Convector What Action is present at this boundary? Battery

  9. Rise W Equivalence of Raising of A Weight

  10. Discussion of the Definition • Positive work is done by a system, during a given process, when the sole effect external to the system could be reduced to the rise of a weight. • Sole Effect: Entire effect (100 %) • External: Only at the boundary or magnitude depends on the boundary • Could be reduced to: It need not be just rise of weight. Any thing that can be translated into to rise of weight.

  11. Hot copper An Unknown Action Turbine Generator Convector

  12. Negative Work • When a system does positive work, its surroundings do an equal quantity of negative work. • Conversely, when surroundings do positive work, the system does and equal quantity of negative work.

  13. Types of Work Transfers • Moving Boundary work (displacement work) • Electrical work • Shaft work • Flowing fluid work

  14. Moving Boundary work (displacement work) • Boundary work occurs when a change in the system causes a force to act on the boundary and make it move.

  15. Simple Processes for Displacement Work : Control Mass

  16. Control Mass : Constant Volume & Pressure Processes

  17. Isothermal Process by A Control Mass

  18. Isothermal Process of Real Gases in a Control Mass • Van der Waals EOS

  19. Displacement Work done by Superheated Steam During An Isothermal Process

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