Ans:
The Otto Cycle is a theoretical thermodynamic cycle that
describes the operation of a typical gasoline-powered internal combustion
engine. It consists of four main processes: intake, compression, power, and
exhaust. Here's a brief explanation of the Pressure-Volume (PV) and
Temperature-Entropy (TS) diagrams for the Otto Cycle:
- Intake:
- In
the PV diagram, an air-fuel mixture is drawn into the cylinder as the piston
moves from top dead center (TDC) to the bottom dead center (BDC) at nearly
constant pressure. This is represented by a horizontal line at low
pressure.
- In
the TS diagram, there is an isentropic compression as air is drawn into
the cylinder and its entropy remains nearly constant while temperature
increases slightly.
- Compression:
- In
the PV diagram, the piston compresses the air-fuel mixture adiabatically
(without heat transfer) as it moves from BDC to TDC. This is represented
by an upward-sloping line with increasing pressure and decreasing volume.
- In
the TS diagram, the compression process is represented by a steep upward
slope as entropy decreases while temperature and pressure increase.
- Power:
- In
the PV diagram, ignition of the compressed mixture leads to a rapid
increase in pressure and volume expansion as the piston moves from TDC to
BDC. This is the power stroke, represented by a downward-sloping line.
- In
the TS diagram, this expansion process corresponds to an isentropic
expansion, characterized by a downward slope with entropy remaining
nearly constant while temperature and pressure decrease.
- Exhaust:
- In
the PV diagram, the exhaust valve opens, and the piston pushes out the
remaining exhaust gases during the exhaust stroke, resulting in a
near-constant pressure and increasing volume.
- In
the TS diagram, the exhaust process corresponds to an isentropic expansion,
similar to the power stroke, but in the reverse direction.
These diagrams illustrate the changes in pressure, volume,
temperature, and entropy during each stage of the Otto Cycle, providing a
visual representation of the engine's thermodynamic behavior.
➽ Question-2: What is tappet clearance?
