00 part1-thremodynamics


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Introduction to Thermodynamics

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00 part1-thremodynamics

  1. 1. Thermodynamics S.Gunabalan Associate Professor Mechanical Engineering Department Bharathiyar College of Engineering & Technology Karaikal - 609 609. e-Mail : gunabalans@yahoo.com
  2. 2. Thermodynamics Thermodynamics is the science of energy transfer and its effect on the physical properties of substances. Thermo = HEAT (or Energy) Dynamics: Movement The Temperature - a quantity which indicates how hot or cold the body is Temperature is indicator of direction for heat flow.
  3. 3. Thermodynamics Thermodynamics is the science of energy transfer and its effect on the physical properties of substances. 1. Macroscopic thermodynamics is only concerned with the effects of the action of many molecules, and these effects can be perceived by human senses. 2. The behaviour of the gas is described by summing up the behaviour of each molecule. Such a study is made in microscopic or statistical thermodynamics.
  4. 4. Thermodynamic System • Thermodynamic system is defined as a region in space upon which attention is concentrated in the analysis of a problem. surroundings : Everything external to the system is called the surroundings or the environment. boundary : The system is separated from the surroundings by the system boundary
  5. 5. Thermodynamic System
  6. 6. Thermodynamic System Open system http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/A_System_And_Its_Surroundings A open system is defined when a fixed volume is under study. There can be mass transfers as well as energy transfers across the boundary.
  7. 7. Thermodynamic System • Truly isolated systems cannot exist in nature, • The only possibility is the universe itself, • So its is a hypothetical concepts http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/A_System_And_Its_Surroundings isolated systems
  8. 8. Thermodynamic System http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/A_System_And_Its_Surroundings Closed systems • A closed system is a system that exchanges only energy with its surroundings, not matter. • Matter can no longer transfer because the lid prevents matter from entering the pan and leaving the pan. Still, the pan allows energy transfer. A closed system always contains the same matter. There can be no mass transfers across the boundary. There may be energy transfer across the boundary.
  9. 9. Thermodynamic System http://nptel.iitm.ac.in/courses/Webcourse- contents/IIT%20Kharagpur/Ref%20and%20Air%20Cond/R&AC%20Web%20files/R&AC%20Lecture%204/hyperlinks/systems.htm Example the contents of a pressure cooker on a stove with its lid tightly closed and the whistle in position, is a closed system as no mass can enter or leave the pressure cooker, but heat can be transferred to it. When the whistle of the pressure cooker blows, then it becomes an open system as steam leaves the cooker. A perfectly insulated, rigid and closed vessel is an example of an isolated system as neither mass nor energy can enter or leave the system.
  10. 10. Properties • Thermodynamic properties are observable or measurable properties of the system(pressure, temperature, volume) – Classification of properties 1. Intensive properties (Independent of mas) Properties have same value in any part of the system and it is independent of mas (pressure, temperature) 2. Extensive properties (mas dependent) depends on mass of the system and de not maintain same value across the system (mass, volume, enthalpy, energy)
  11. 11. State The specific condition of the system is called State of the system. the properties are used to describe the state of the system. Path : The succession of states passed through during a change of state is called the path Process: the path is completely specified, the change of state is called a process
  12. 12. Thermodynamic Equilibrium • when no change in any macroscopic property then the system is in equilibrium
  13. 13. Applications of thermodynamics •To predict the equilibrium state of a reactive mixture as well as the natural direction of change in a system not at equilibrium •thermodynamics can’t predict how long it takes for equilibrium to be reached
  14. 14. Reference • Nag, P. K. 2002. Basic and applied thermodynamics. Tata McGraw-Hill, New Delhi. • http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodyn amics/A_System_And_Its_Surroundings • http://nptel.iitm.ac.in/courses/Webcourse- contents/IIT%20Kharagpur/Ref%20and%20Air%20Cond/R&AC %20Web%20files/R&AC%20Lecture%204/hyperlinks/systems. htm ( date 25-june-2013)