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Thermodynamics

Table of Contents

  1. Introduction to Thermodynamics
    • Definition and Importance
    • Historical Development
  2. Key Concepts and Terminologies
    • Heat, Energy, and Work
    • Systems and Surroundings
    • State Functions vs. Path Functions
  3. Types of Thermodynamic Systems
    • Open Systems
    • Closed Systems
    • Isolated Systems
  4. Laws of Thermodynamics
    • Zeroth Law
    • First Law
    • Second Law
    • Third Law
  5. Types of Thermodynamic Processes
    • Isothermal Process
    • Adiabatic Process
    • Isobaric Process
    • Isochoric Process
  6. Heat and Energy Transfer
    • Modes of Heat Transfer: Conduction, Convection, Radiation
    • Internal Energy and Enthalpy
  7. Work in Thermodynamics
    • Work Done by Expanding Gases
    • PV Diagrams and Area Interpretation
  8. Thermodynamic Cycles
    • Carnot Cycle
    • Rankine Cycle
    • Otto Cycle and Diesel Cycle
  9. Entropy and the Second Law of Thermodynamics
    • Entropy as a Measure of Disorder
    • Entropy Changes in Processes
  10. Applications of Thermodynamics
    • Engines and Refrigerators
    • Power Plants
    • Biological Systems
  11. Real-World Examples of Thermodynamics
    • Everyday Heat Transfer Examples
    • Industrial Applications
  12. Advanced Topics in Thermodynamics
    • Thermodynamics of Non-Ideal Gases
    • Statistical Thermodynamics

 


1. Introduction to Thermodynamics

Thermodynamics is the branch of physics that deals with the relationships between heat, work, and energy. It studies how energy is transformed and transferred in various systems.

Importance
  • Explains natural phenomena, from boiling water to the workings of a car engine.
  • Forms the backbone of engineering disciplines like mechanical, chemical, and aerospace engineering.
Historical Development
  • Early studies of heat engines in the 17th century.
  • Development of the laws of thermodynamics in the 18th and 19th centuries by scientists like Joule, Carnot, Clausius, and Kelvin.

2. Key Concepts and Terminologies

Heat
  • Energy transferred due to temperature differences.
  • Measured in joules (J) or calories (cal).
Work
  • Energy transfer associated with force acting over a distance or gas expansion/compression.
Energy
  • Total capacity to do work, comprising kinetic and potential energy.
Systems and Surroundings
  • System: The part of the universe being studied.
  • Surroundings: Everything outside the system.
State Functions vs. Path Functions
  • State Functions: Properties that depend only on the current state (e.g., temperature, pressure, energy).
  • Path Functions: Depend on the process taken (e.g., work, heat).

3. Types of Thermodynamic Systems

Open Systems
  • Exchange of both energy and matter with surroundings.
  • Example: A boiling pot of water.
Closed Systems
  • Exchange energy but not matter.
  • Example: A sealed container.
Isolated Systems
  • No exchange of energy or matter.
  • Example: A thermos flask.

4. Laws of Thermodynamics

Zeroth Law:
  • Defines temperature and thermal equilibrium.
  • If AA is in equilibrium with BB, and BB is in equilibrium with CC, then AA is in equilibrium with CC.
First Law:
  • Energy Conservation: Energy cannot be created or destroyed.
  • Mathematically: ΔU=Q−W\Delta U = Q – W, where
    • ΔU\Delta U: Change in internal energy
    • QQ: Heat added to the system
    • WW: Work done by the system
Second Law:
  • Entropy of an isolated system always increases.
  • Heat cannot spontaneously transfer from a colder body to a hotter body.
Third Law:
  • Entropy approaches zero as temperature approaches absolute zero.

5. Types of Thermodynamic Processes

Isothermal Process
  • Temperature remains constant (ΔT=0\Delta T = 0).
  • Example: Slow expansion of gas in a piston.
Adiabatic Process
  • No heat exchange (Q=0Q = 0).
  • Example: Compression in an insulated system.
Isobaric Process
  • Pressure remains constant (ΔP=0\Delta P = 0).
  • Example: Heating water at atmospheric pressure.
Isochoric Process
  • Volume remains constant (ΔV=0\Delta V = 0).
  • Example: Heating gas in a rigid container.

6. Heat and Energy Transfer

Modes of Heat Transfer
  1. Conduction: Transfer through a solid medium.
    • Example: Heating one end of a metal rod.
  2. Convection: Transfer in fluids due to motion.
    • Example: Boiling water.
  3. Radiation: Transfer via electromagnetic waves.
    • Example: Heat from the Sun.
Internal Energy and Enthalpy
  • Internal Energy (UU): Sum of kinetic and potential energy of particles.
  • Enthalpy (HH): Heat content of a system (H=U+PVH = U + PV).

7. Work in Thermodynamics

Work Done by Expanding Gases
  • Work W=PΔVW = P \Delta V, where PP is pressure and ΔV\Delta V is change in volume.
PV Diagrams
  • Graphical representation of work done during processes.

8. Thermodynamic Cycles

Carnot Cycle
  • Theoretical cycle with maximum efficiency.
Rankine Cycle
  • Used in steam power plants.
Otto Cycle and Diesel Cycle
  • Describe internal combustion engines.

9. Entropy and the Second Law of Thermodynamics

Entropy (SS)
  • Measure of disorder or randomness.
Entropy Changes
  • Increases in irreversible processes.

10. Applications of Thermodynamics

Engines
  • How thermodynamics drives cars and jets.
Refrigerators
  • Heat transfer from cooler to warmer spaces.
Biological Systems
  • Energy transformations in living organisms.

11. Real-World Examples

Heat Transfer
  • Insulation in homes.
Industrial Uses
  • Chemical plants and manufacturing processes.

12. Advanced Topics in Thermodynamics

Non-Ideal Gases
  • Behavior under extreme conditions.
Statistical Thermodynamics
  • Microstates and probabilities.