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2.  Introduction  Microscopic and macroscopic view  Thermodynamic system and control volume  Thermodynamic properties  State, process and cycle  Thermodynamic equilibrium  Quasi – state process 2

3.  Thermodynamic can be defined as the science of energy.  It deals with the most basic processes occurring in nature.  One of the most fundamental laws of nature is the conservation of energy principle.  It simply states that during an interaction, energy can change from one form to another but the total amount of energy remains constant. 3

4.  Thewordthermodynamicsismadeupfrom two Greek words: (i) Thermo - hot or heat (ii) Dynamic – power or powerful, the study of matter in motion. Thermodynamicsmeansstudyofheatrelated to matter in motion. 4

5.  Thermodynamic may be defined as: i. Sciencethatdealswiththeinteractionbetween energy and material system. ii. Law of science which deals with the relations among heat, work and properties of system which are in equilibrium. 5

6.  There are basically four laws, i. Zerothlaw:representstheconceptof temperature, and deals with thermal equilibrium. 6

7. ii.Firstlaw:representstheconceptofinternal energy. 7

8. iii. Second law : indicates the limit of converting heat into work and introduce principle of increase of entropy. 10

9. iv. Third law : concerned with the level of availability of energy and defines the absolute zero of entropy. 9

10. Classical thermodynamics: A macroscopic approachtothestudyof thermodynamics that does not require a knowledge of the behavior of individual particles. Itprovidesadirectandeasywaytothesolutionof engineering problems and it is used in this text. Statistical thermodynamics : A microscopic approach,basedontheaverage behavior of large groups of individual particles. It is used in this text only in the supporting role. 10

11.  System: A quantity of matter or a region in space chosen for study.  Surroundings:Themassorregionoutsidethe system 11

12.  Boundary:Therealorimaginarysurfacethat separates the system from its surroundings. Theboundaryofasystemcanbefixedor movable. Systemsmaybeconsideredtobeclosedor open. 12

13.  Closed system (Control mass): A fixed amount of mass, and no mass can cross its boundary. 13

14. Open system : A properly selected region in space. It usually encloses a device that involves mass flow such as a compressor, turbine, or nozzle. Both mass and energy can cross the boundary of a control volume. 14

15. Isolated System: In this system, fixed mass and fixed energy and there is no mass or energy transfer across the system boundary as shown in fig. The thermos flask is example of an isolated system. 15

16.  Control volume: In most of engineering problems of open system, (such as in an engine, an air compressor, turbine etc) the mass of the system is not fixed. Therefore, in the analysis, attention is focused on a certain volume in space surrounding the system (equipment), known as the Control volume. The control volume bounded by the surface is called Control surface. 16

17.  Control volume: 17

18.  Property: Any characteristic of a system. Some familiar properties are pressure P, temperature T, volume V, and mass m. Properties are considered to be either intensive or extensive.  Intensive properties: Independentofthemassofasystem,suchastemperature, pressure, and density.  Extensive properties: Whose values depend on the size—or extent—of the system.  Specific properties: Extensive properties per unit mass. And they became intensive properties. 20

19.  State: Itistheconditionofthesystemataninstantoftimeas described by its properties. Consider a system that is not undergoing any change. At this point, all the properties can be measured or calculated throughout the entire system, at a given state, all the properties of a system have fixed values. If the value of even one property changes, the state will change to a different one. 19

20.  Process: Any change that a system undergoes from one state to another state is called a process. 20

21.  Cycle: It is defined as a series of state changes such that the final state is identical with the initial state. The cycle as shown in fig. consists of two processes as 1-2, and 2-1. 21

22. Thetemperatureasameasureofhotnessor coldness. It may be defined as 1. Degree of hotness or coldness 2. Driving force causing the heat transfer 3. Determinethesystemisinthermalequilibrium with another system or not 22

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24.  ― If two systems are each in thermal equilibrium with a third system, they are also in thermal equilibrium with each other. ‖ 24

25.  Application of Zeroth law: istheconceptof Zerothlawofthermodynamics temperature. The third system C is called thermometer. It permits to test the equality of temperature without actually bringing the system in thermal contact. 25

26.  In macroscopic thermodynamic analysis, we consider the matter as continuous rather than considering of discrete particles.  The spaces between and within the molecules are not considered.  Generallyweconsiderpressureandtemperaturesof large number of molecules in the system.  Such continuous substance is known as ―Continuum ‖. 26

27.  Thermodynamic equilibrium: The word equilibrium implies a state of balance. This system is said to exist in a state of equilibrium when no change in any macroscopic property. “ A system is said to be in a state of thermodynamic equilibrium if the value of properties is the same at all points in the system.” A system will be in a state of equilibrium, if the condition for the following three types of equilibrium are satisfied : i. Thermal equilibrium ii. Mechanical equilibrium iii. Chemical equilibrium 27

28.  Thermal equilibrium: If the temperature of the system does not change with time and has same value at all points of the system, the system said in thermal equilibrium. 28

29.  Mechanical equilibrium: A system is in mechanical equilibrium if there are no unbalanced forces within the system or between surroundings. The pressure in the system is same at all points and does not change with respect to time. 29

30.  Chemical equilibrium: A system is in chemical equilibrium if its chemical composition does not change with time and no chemical reaction takes place in the system. 30

31.  When a process proceeds in such a way that the system remains close to an thermodynamic equilibrium state at all times, it is called a Quasi- static process.  A quasi-static process is also called a reversible process. The main characteristic of this process is infinite slowness. 31

32.  The quasi-static equilibrium process is an idealized process and many actual processes can be modeled as quasi-static equilibrium with negligible error.  This process produces maximum work or consumes less work, so this processes serve as standards to which actual processes can be compared. 32

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36.  The heat and work are form of energy. A closed system and surroundings can interact in two ways: (1)By work transfer and (2)By heat transfer 36

37.  Mechanical work: Work done = Force * Distance 37

38.  Thermodynamics Work: ― It is the energy transferred, without transfer of mass across the boundary of a system because of an intensive property difference other than temperature that exist between system and surroundings. ‖ Work may be defined as ―a transient quantity which only appears at the boundary while a change of state is taking place within a system. ‖ 38

39.  Displacement work: Consider a system, formed by a gas contained in a piston cylinder arrangement as shown in Fig. Due to pressure of gas acting on the face of the piston, the piston move outward through a small distance dx, during a small time interval dt. Assume that pressure p acting on piston is constant. The work done by the system is, 39

40.  Displacement work: 40

41.  Displacement work: 41

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43.  Shaft work: 43

44.  Paddle Wheel Work: 44

45.  Thermodynamics Work: Accordingtodefinitionofmechanicalwork,itisnotwork because there is no force has moved through a distance. But according to thermodynamics work definition, the battery does work as the electrical energy crosses the system boundary. 50

46.  Thermodynamics Work: consider an electrical storage battery as a system in which the terminals are connected with a resistance by means of a switch as shown in fig. When the switch is closed, the current flows through the resistance coil and the resistance become warmer. 46

47.  Thermodynamics Work: Theresistanceisreplacedbyan wind electrical astring motorwith andliftthe frictionlesspulleywhichcan suspended mass as shown in fig. Therefore, only effect is the work done by system, is the rising of a mass. So, interaction of battery with resistance coil is a work, 47

48.  Heat is defined as form of energy that is transferred between system and surroundings or between two systems due to temperature difference. 48  Two closed systems at different temperature,  Due to temperature difference,  Thermal equilibrium,  “Heat is the form of energy which appears at the boundary when a system changes its state due to a difference in temperature between system and its surroundings."

49.  Sign convention : 49

50.  Similarities: 60 not properties of system boundary phenomenon associated with process, not a state. These energies interactions occurs only when a system undergoes change of state.

51.  Dissimilarities : 51  Heat is energy interaction due to temperature difference. Work is energy interaction by reasons other than temperature difference.  In stable system there can not be work transfer, however, there is no restriction for the transfer of heat.  Heat is low grade energy while work is high grade energy.

52.  The property of a system which does not depends on path of process, but depends on state, this property is called point function.  Thermodynamic properties are point functions, for given state, there is a definite value for each property.  Thedifferentialofpointfunctionsareexactorperfect differentials and the integration is simply,  The change in volume depends only on the initial and final state of the system, not depends on the path the system follows. 52

53.  There are certain quantities which can not be located on a graph by a point but are represented by the area on that graph. Those quantities are dependent on the path of the process and are called path function.  Heat and work are inexact differentials. Their change can not be written as difference between their initial and final states. 53

54.  Consider several reversible processes such as P, Q and R from state 1 to state 2 as shown in fig.  The work done for each process is represented by area under each curve on p-V diagram.  From the fig., it is clear that the work is different in each process because process (path) depends on the nature of the process.  The amount of work involved in each case is not a function of initial and final (end) states of the process, is not a property of state function and its depends on the path of the system follows in going from state 1 to state 2 Therefore, work is a path function. 54

55.  A system does not posses work, but work is a mode of transfer of energy. This transfer occurs only at the boundaries of the system during a change of state of the system. 70

56.  A reversible process also known as quasi-static process is one which can be reversed at any stage to the same initial condition and also leaving no effect on the surroundings. That means after completely reversing the process, the system and surroundings are exactly restored to � their � initial condition. Hence a reversible process has following characteristics : It must pass through the same states on the reversed path as were initially visited on the forward path. This process when undergoes will leave no history of events in the surroundings. It must pass through a continuous series of equilibrium states. No real process is truly reversible but some processes may approach reversibility to close approximation. An irreversible process is one which cannot be reversed or which is not reversible e.g. heat transferred through a finite temperature difference or work done on a gas enclosed in cylinder piston arrangement etc. Reversible and Irreversible process

57. Thermodynamics Processes

58. First law applied to a process

59. 100 J of work is done on a system internal energy increases by 74 J how much energy is transferred as heat Q = 74 J + (-100 J) Q = -26 J (this is that heat lost in the process)