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Explore the definition of thermodynamic work, its broader applications, and how it relates to mechanical work. Discover types of work transfers and simple processes involved in displacement work. Delve into historical perspectives and practical examples to deepen your understanding.
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Thermodynamic Work P M V Subbarao Professor Mechanical Engineering Department I I T Delhi Development of Power for Different Needs!!!
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.
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?
S Mechanical work System Before triggering Surroundings F After triggering
S1 Thermodynamic Work W W Mechanical Work is Thermodynamic work and vice versa. F.S = W*S1
Broader Applications of the Thermodynamic Work Convector What Action is present at this boundary? Battery
Rise W Equivalence of Raising of A Weight
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.
Hot copper An Unknown Action Turbine Generator Convector
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.
Types of Work Transfers • Moving Boundary work (displacement work) • Electrical work • Shaft work • Flowing fluid work
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.
Isothermal Process of Real Gases in a Control Mass • Van der Waals EOS
Displacement Work done by Superheated Steam During An Isothermal Process