HEAT ENGINES AND REFRIGERATION

1. HEAT ENGINES AND REFRIGERATION PRESENTATION BY GROUP 1 CLASS D IDEHEN OSAHON MOSES 20559 AYOKUNLE OLUWOLE DAVID 20530 AHMAD ABUBAKAR SHEHU 20464 NWABUEZE GIFT CHIMUANYA 20614 AKHIGBE PETER OSEREME 20507 MBEE OLEMAKPADU NELSON 20821 ANYANWU OBINNA THOMPSON 20825

2. OUTLINE • INTRODUCTION • THEORETICAL ANALYSES OF CYCLES • PRACTICAL APPLICATIONS • FURTHER RESEARCH • CONCLUSION

3. INTRODUCTION What is a Heat Engine? Any device that transforms heat partly into work The working substance could be Air and fuel mixture in ICE Steam in Steam Engines

4. First Law of Thermodynamics INTRODUCTION -a principle of conservation of energy

5. HEAT Q Heat Applied W Work Done

6. INTRODUCTION Second Law of Thermodynamics • It is impossible to transform all of the heat energy transferred to a system into useful work.

7. INTRODUCTION Forward and Reverse engines Forward Engines Reverse Engines • Heat moves from hot source to cold sink • Work is done by the system • Examples are ICE,SE • Heat moves from cold source to a hot sink • Work is done on the system • Examples are Refrigerators and A/C

8. THEORETICAL ANALYSIS Carnot Cycle Best Efficient Heat supplied at upper fixed temperature Rejected at lower fixed temperature 1to 2 Isothermal heat Supply 3to 4 Isothermal heat rejection 2to 3 Adiabatic Expansions (Isentropic) 4 to 1 Adiabatic Compressions (Isentropic) The Carnot Efficiency (1)

9. THEORETICAL ANALYSIS Otto Cycle (Ideal Air Standard Cycle - Petrol Engine) 1 to 2 Isentropic Compressions 2 to 3 Reversible constant Volume heating 3 to 4 Isentropic Expansions 4 to 1 Constant Volume Heating Compression ratio (2) Efficiency , (3) (4) (5) Otto Cycle efficiency is a function of compression ratio.

10. THEORETICAL ANALYSIS Diesel Cycle Develop by Diesel in 1892 Compression Ignition 1 to 2 Isentropic Compressions 2 to 3 Reversible Constant Pressure heating 3 to 4 Isentropic Expansion 4 t0 1 Constant Volume cooling. Making similar computations (6) (7) The efficiency depends on the compression and cut off ratios.

11. THEORETICAL ANALYSIS Refrigeration Cycle 3 2 Q2 1 4 W (7) (8) Q 1

12. PRACTICAL APPLICATIONS • Internal Combustion Engine (in cars and airplanes)

13. 2. Gas Turbine Engine Gas turbines are similar to piston engines except that the four steps occur at different places. The four sections include: 1. The inlet section 2. The compressor section 3. The combustion section (the combustor) 4. The turbine (and exhaust) section. Applicable in airplanes and gas power plants

14. 3. Refrigerator and Air conditioner The major parts of the AC/refrigerator are: Evaporator - Receives the liquid refrigerant. Converts liquid to gas Compressor - A pump that pressurizes gaseous refrigerant Condenser - Facilitates heat transfer to the surrounding. Gas is condensed to cool liquid Expansion valve - regulates refrigerant flow into the evaporator Major differences are : supply of gases, circulation system and type of vaporization

15. FURTHER RESEARCH • Efficiency of heat Engines • Pollution • Magnetic heat Engines • Electric Cars

16. CONCLUSION • Heat Engines and Refrigeration play important roles in our lives.

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