The document describes three common internal combustion engine cycles: the Otto, Diesel, and Dual cycles. It provides diagrams and equations to illustrate the thermodynamic processes involved in each cycle, including compression, combustion, and expansion processes. Key parameters like compression ratio, cut-off ratio, pressure ratio, and thermal efficiency are defined. The cycles are compared in terms of their heat addition processes, net work output, and thermal efficiency calculations.

1. Internal Combustion
Engine Cycle
• The OTTO CYCLE
• The DIESEL CYCLE
• The DUAL CYCLE

2. INTERNAL
COMBUSTION
ENGINE
By. Engr. Yuri G. Melliza

3. Internal Combustion Engine
Cycle
Air Standard Cycle
 Otto Cycle
 Diesel Cycle
 Dual Cycle

4. Otto Cycle
Inventor: Nikolaus Otto (1832 – 1891)
Processes:
1 to 2: Isentropic Compression (S = C)
2 to 3: Constant Volume Heat Addition
(V = C)
3 to 4: Isentropic Expansion (S = C)
4 to 1: Constant volume Heat Rejection
(V = C)

5. P V Diagram
P
V
1
4
3
2
S = C
S = C
VD
CVD

6. T S Diagram
T
S
1
4
3
2
V = C
V = C
QR
QA

7. Compression Ratio
Heat Added (V = C)

8. Heat Rejected (V = C)
Net Work

9. Thermal Efficiency
100%
x
Q
Q
-
1
e
100%
x
Q
Q
-
Q
e
100%
x
Q
W
e
A
R
A
R
A
A
















10. 100%
x
(r)
1
-
1
e
100%
x
T
T
T
T
e
1
-
k



















2
3
1
4
1
Percent Clearance
100%
x
lume
Vo
nt
Displaceme
TDC
at
Volume
C 

11. C
C
r
CV
V
100%
x
V
V
C
D
2
D
2




1
KPa
V
W
P
D
m 
Mean Effective Pressure
W VD Pm
KJ m3 Kpa
KJ/kg m3/kg Kpa
KW m3/se
c
KPa
kg
m
V
m
V
V
V
3
D
3
D
)
(
)
(
2
1
2
1







12. Diesel Cycle
Inventor: Rudolf Christian Karl Diesel
(1858-1913)
Processes:
1 to 2: Isentropic compression (S = C)
2 to 3: Constant Pressure Heat Addition
(P = C)
3 to 4: Isentropic Expansion (S = C)
4 to 1: Constant Volume Heat Rejection
(V = C)

13. P V Diagram
P
V
1
4
3
2
S = C
S = C
VD
CVD

14. T S Diagram
T
S
1
4
3
2
V = C
P = C
QR
QA

15. Compression Ratio
Cut-Off Ratio

16. Heat Added (P = C)
Heat Rejected (V = C)

17. Net Work

18. Thermal Efficiency
100%
x
Q
Q
-
1
e
100%
x
Q
Q
-
Q
e
100%
x
Q
W
e
A
R
A
R
A
A
















19. 100%
x
r
k
r
r
1
-
1
e
100%
x
T
T
k
T
T
e
c
k
c
1
-
k





























1
1
1
2
3
1
4
(
)
(
)
(
Percent Clearance
100%
x
lume
Vo
nt
Displaceme
TDC
at
Volume
C 

20. C
C
r
CV
V
100%
x
V
V
C
D
2
D
2




1
KPa
V
W
P
D
m 
Mean Effective Pressure
W VD Pm
KJ m3 Kpa
KJ/kg m3/kg Kpa
KW m3/se
c
KPa
kg
m
V
m
V
V
V
3
D
3
D
)
(
)
(
2
1
2
1







21. Dual Cycle
Processes:
1 to 2: Isentropic compression (S = C)
2 to 3: Constant Volume Heat Addition
QA1(V = C)
3 to 4: Constant Pressure Heat addition
QA2(P = C)
4 to 5: Isentropic Expansion (S = C)
5 to 1: Constant Volume Heat Rejection
(V = C)

22. PV Diagram
P
V
1
3
2
5
S = C
S = C
4

23. TS Diagram
T
S
5
3
2
4
1
V = C
P = C
QA1
QA2
QR

24. Cut-Off Ratio
Compression Ratio
Pressure Ratio

25. Heat Added

26. Net Work
Heat Rejected

27. Thermal Efficiency
100%
x
Q
Q
-
1
e
100%
x
Q
Q
-
Q
e
100%
x
Q
W
e
A
R
A
R
A
A
















28. 100%
x
r
kr
r
r
r
r
1
-
1
e
100%
x
T
T
k
T
T
T
T
e
c
p
p
k
c
p
1
-
k 
































)
(
)
(
)
(
)
(
)
(
1
1
1
1
3
4
2
3
1
5
Percent Clearance
100%
x
lume
Vo
nt
Displaceme
TDC
at
Volume
C 

29. C
C
r
CV
V
100%
x
V
V
C
D
2
D
2




1
W VD Pm
KJ m3 Kpa
KJ/kg m3/kg Kpa
KW m3/se
c
KPa
KPa
V
W
P
D
m 
Mean Effective Pressure
kg
m
V
m
V
V
V
3
D
3
D
)
(
)
(
2
1
2
1





