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Otto Cycle

31 flashcardsby Irish
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1
What is the Constant Volume Cycle also known as?
Otto Cycle
2
What type of engines does the Otto Cycle apply to?
Spark-ignition internal combustion engines, such as petrol engines
3
Why is it called the Constant Volume Cycle?
Because heat addition and rejection occur at constant volume
4
How many processes does the Otto Cycle consist of?
Four
5
What are the two types of processes in the Otto Cycle?
Two adiabatic (isentropic) processes and two constant-volume processes
6
What does the horizontal axis represent in the Pressure-Volume (P-V) diagram?
Volume (V)
7
What does the vertical axis represent in the Pressure-Volume (P-V) diagram?
Pressure (P)
8
What does the horizontal axis represent in the Temperature-Entropy (T-S) diagram?
Entropy (S)
9
What does the vertical axis represent in the Temperature-Entropy (T-S) diagram?
Temperature (T)
10
What happens in the 1 → 2 process of the Otto Cycle?
Adiabatic (isentropic) compression
11
What happens to the piston in the 1 → 2 process?
It moves upward, compressing the air inside the cylinder
12
Why does pressure and temperature increase during 1 → 2?
Because compression is adiabatic, meaning no heat is transferred
13
What happens in the 2 → 3 process of the Otto Cycle?
Constant volume heat addition
14
What happens at Top Dead Center (TDC)?
Fuel is ignited, and heat is added at constant volume
15
What happens to pressure and temperature in the 2 → 3 process?
They increase sharply
16
Why is the 2 → 3 process represented as a vertical line in the P-V diagram?
Because the volume remains constant while pressure increases
17
What happens in the 3 → 4 process of the Otto Cycle?
Adiabatic (isentropic) expansion
18
What happens to the piston in the 3 → 4 process?
It is pushed downward by the expanding gases, performing work
19
Why is the 3 → 4 process adiabatic?
Because no heat is lost or gained during expansion
20
What happens to pressure and temperature during the 3 → 4 process?
They decrease while volume increases
21
Why does entropy remain constant in the 3 → 4 process in the T-S diagram?
Because it is an adiabatic (isentropic) process
22
What happens in the 4 → 1 process of the Otto Cycle?
Constant volume heat rejection
23
What happens at Bottom Dead Center (BDC)?
The exhaust valve opens, and heat is rejected at constant volume
24
What happens to temperature and pressure in the 4 → 1 process?
They drop suddenly
25
Why is the 4 → 1 process represented as a vertical line in the P-V diagram?
Because volume remains constant while pressure decreases
26
What does the P-V diagram represent?
The engine stroke cycle, showing pressure and volume changes
27
What does the T-S diagram represent?
Temperature and entropy changes, showing heat addition and rejection
28
Why are the 1-2 and 3-4 processes curved in the P-V diagram?
Because they are adiabatic (isentropic) processes
29
Why are the 2-3 and 4-1 processes vertical in the P-V diagram?
Because they occur at constant volume
30
What does the area enclosed in the P-V diagram represent?
The net work done per cycle
31
Why is the Otto Cycle important for engineers?
It helps analyze and improve real internal combustion engines by understanding thermodynamic limits
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