thermal engineering presetation fro engg

engg

1. Otto Cycle Operation The  Otto cycle  is a thermodynamic cycle that describes the operation of a typical spark-ignition internal combustion engine It consists of four stages:  Intake, Compression, Power, and Exhaust .

2. 1. Intake (Process 0-1) Air and fuel mixture enters the cylinder through the intake valve at constant pressure . The piston moves from Top dead center (TDC) to Bottom dead center (BDC), drawing in the mixture. The volume of the cylinder increases, and the pressure remains constant.

3. 2. Compression (Process 1-2) The intake valve closes , and the piston moves back to TDC , compressing the air-fuel mixture . The volume of the cylinder decreases, and the pressure increases adiabatically (no heat transfer). The compression ratio (CR) is the ratio of the volume at BDC to the volume at TDC.

4. 3. Power (Process 2-3-4) Spark plug ignites the compressed air-fuel mixture, causing a rapid expansion . The piston moves from TDC to BDC , converting the chemical energy of combustion into mechanical energy. The pressure and temperature of the gas decrease as it expands in the process of expansion (process 3-4).

5. 4. Exhaust (Process 4-1-0) The exhaust valve opens, and the piston moves from BDC to TDC, expelling the exhaust gases from the cylinder. The volume of the cylinder decreases, and the pressure remains constant.