nrew 2dyeryeryeyeyerrrrrrrrrrrrrrrrrrrrrrrrrr45.pptx

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1. Energy & its interactions Static Form (Total Energy) Dynamic Form Macroscopic Microscopic Kinetic Energy [ velocity] Potential Energy [elevation] Internal Energy Sensible Latent Nuclear Chemical Heat Work Mass Molecular Translation Molecular Rotation Electron Translation Molecular Vibration Electron Spin Nuclear Spin Flow Energy [pressure] Open System First Law of Thermodynamics

2. 70 o C 10 o C 25 o C 70 o C 10 o C 25 o C Surrounding (C) (A) (B) (B) Laws of Thermodynamics Zeroth law of thermodynamics Concept of thermal equilibrium You must play the game First law of thermodynamics Concept of change in energy ( E ) You can’t win the game Third law of thermodynamics Concept of absolute entropy You can’t quit the game Second law of thermodynamics Concept of change in entropy ( S ) You can’t break even in the game

3. Open System – Steady flow devices Hair dyer Water heater Air compressor Shower mixer Ceiling fan Water pump condenser Shower mixer

4. Introduction to the Second Law of Thermodynamics The use of the second law of thermodynamics is not limited to identifying the direction of processes. The second law also asserts that energy has quality as well as quantity. The first law is concerned with the quantity of energy and the transformations of energy from one form to another with no regard to its quality. Preserving the quality of energy is a major concern to engineers, and the second law provides the necessary means to determine the quality as well as the degree of degradation of energy during a process.

5. The Second Law of Thermodynamics Kelvin–Planck Statement It is impossible for any device that operates on a cycle to receive heat from a single reservoir and produce a net amount of work. A device that violates the Kelvin–Planck statement of the second law. Clausius Statement It is impossible to construct a device that operates in a cycle that transfers heat from a lower-temperature body to a higher-temperature body without any external agency. A device that violates the Kelvin–Planck statement of the second law.

6. Equivalence of the Two Statements

7. Carnot Cycle   The Carnot Principles 3 4 1 2 For any reversible process

8. Heat Engine Refrigerator Heat Pump Heat Pump Heat Pump Heat Pump

9. For any process, the Clausius inequality gives   ; a quantity whose cyclic integral is zero depends on the state only and not the process path, and thus it is a property. Clausius realized in 1865 that he had discovered a new thermodynamic property, and he chose to name this property entropy   Entropy Entropy can be viewed as a measure of molecular disorder, or molecular randomness

10. According to 2 nd law of Thermodynamics, A process can occur in a certain direction only, not in any direction, and entropy is always generated during the process. Low entropy generation High entropy generation Entropy in everyday life Entropy is a non-conserved property, and there is no such thing as the conservation of entropy principle. Entropy generation is a measure of the magnitudes of the irreversibilities during that process

11. Exergetic Efficiency   Exergy – maximum work potential that can be extracted from the given energy The actual work delivered by the system

12. Energy Balance Entropy Balance Exergy Balance Closed System Closed System Closed System Open System Open System Open System   Heat or Work     Heat     Heat or Work   Heat or Work or mass       Heat or mass     Heat or Work or mass              

13. Energy, Entropy, and Exergy transfer Heat Work Mass Energy Entropy Exergy Based on the energy balance equation Based on the type of process               Closed system   Open system  

14. Fluid Mechanics

15. Fluid : A substance undergoes deformation continuously when acted upon by shearing stress of any magnitude Solid Fluid Shear Stress  Shear Strain Shear Stress  rate of strain (A) (B)

16. Classification of Fluid Flow 1D Uniform Vs Non-Uniform

17. Fluid Properties Mass Weight Volume Density Specific volume Specific weight Specific gravity Temperature Pressure Compressibility factor Isothermal compressibility Coefficient of volume expansion Specific heat capacity Vapour pressure Internal energy Enthalpy Kinetic energy Potential energy Flow energy Dynamic viscosity Kinematic viscosity Surface tension

18. Mass, Weight, Volume & Density Mass (m): Quantitative measure of inertia . The inertial mass is a measure of an object's resistance to acceleration when a force is applied. i.e., resistance to a change in velocity. (kg) Weight (W): The weight of an object (W) is the magnitude of the force acting on the object due to Earth’s gravity field, i.e., the acceleration produced by gravity (N) Volume (V): It is the amount of space an object can takes up. (m 3 ) Density ( ) : It is a measure of how much matter occupies a given amount of space. It is quantified with the ratio of mass per unit volume.  = m / V (kg/m 3 )

19. Specific Volume, Specific Weight & Specific Gravity or Relative density Specific volume ( v ): It is defined as volume of a fluid occupied by a unit mass. In other words, it is the reciprocal of density. (m 3 /kg) Density Tower Specific Weight ( ): It is defined as the weight of the fluid per unit volume. (N/m 3 ) Specific gravity (SG): the ratio of a fluid’s density to that of a standard reference fluid (water for liquids/solids, air for gases) at STP.