Thermodynamics ISOLATED SYSTEM EVVVHGYT.pptx

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1. Thermodynamics

2. Thermodynamics Thermodynamics is the branch of science that deals with the relationships between heat and other forms of energy . Energy of a body is its capacity to do work.

3. System : A thermodynamic system is defined as a quantity of matter or a region in space which is selected for the study . Surroundings: The mass or region outside the system is called surroundings . Boundary : The real or imaginary surfaces which separates the system and surroundings is called boundary. Thermodynamic System and Surrounding

4. Types of thermodynamic systems: Isolated system: neither energy (work or heat) nor mass transfer with its surrounding . Closed system: No mass transfer, but have energy transfer with its surrounding. Open system: Both energy and mass transfer with its surrounding.

5. Thermodynamic Process: Cycle process: system and surrounding return to their original condition in the final process . Reversible process: system and surrounding return to their original condition when stop the process. Irreversible process: system and surrounding can't return to their original condition.

6. Lows of thermodynamics ZEROTH LAW OF THERMODYNAMICS: • If objects ‘A’ and ‘C’ are in thermal equilibrium with ‘B’, then object ‘A’ is in thermal equilibrium with object ‘C’. Practically this means all three objects are at the same temperature and it forms the basis for comparison of temperatures. • If a=b; b=c then a=c

7. First Law of thermodynamic Energy can't be created nor destroyed, but it can convert from one form to another.

8. Second Law of thermodynamics: The total entropy of an isolated system always increases over time.

9. Gas Laws: Boyles Law: Pressure is inversely proportional to Volume when Temperature is constant. Pv =C Charles Law: Volume is directly proportional to temperature when pressure is constant. 𝑉/ 𝑇 = 𝐶 Idea gas equation of state : PV= mRT Universal Gas Constant ( R): 8.314 KJ/ Kmol

10. Internal Combustion engines combustion takes place inside a cylinder . Spark Ignition Engine (S.I. Engine) Petrol is used as the fuel  Air and fuel (petrol) enter to cylinder and then compressed . Compression Ignition Engines (C.I. Engines) Diesel is used as the fuel Only air enters to cylinder and then compressed.

11. 4 stroke petrol engine Suction or intake stroke: Inlet valve is opening, Air and petrol enter, outlet valve is closed. Compression Stroke: Both valves are closed, Both air and petrol are compressed. Power or Expansion Stroke: Air and Petrol are Combustion, piston move down cause expansion. Exhaust Stroke: Outlet valve open, Combustion gases go out after expansion, Inlet valve closed.

12. Carnot cycle It is a reversible thermodynamic cycle established by Sadi Carnot.

13. Brayton Cycle It is the ideal cycle for Gas Turbine. Heat is added and rejected at constant pressure. It is used in aircraft propulsion and electric power generation.