1. Strategies for Complete Expansion in I.C. Engine
P M V Subbarao
Professor
Mechanical Engineering Department
Achieve Maximum Work Output….

2. Actual Scope for Expansion Process

3. work of Compression Process

4. Work of Expansion Process

5. Work of Exhaust Process

6. Work of Intake Process

7. The Model Four Stroke Engine
Number of cylinders: 4
Supercharged: No
Global piston displacement: 1202 cc
Individual piston displacement: cc
Bore: 72.6 mm
Stroke: 72.6 mm
Compression ratio: 10:1
Number of intake valves: 1
Intake valve, diameter: 26 mm
Number of exhaust valves: 1
Exhaust valve diameter: 26 mm

8. Work Distribution Analysis of Conventional S. I
Work Distribution Analysis of Conventional S.I. Engine Indicative Cycle at Design Conditions
Work transfer during compression process: J
Work transfer during Expansion process: J
Work transfer during Exhaust process: J
Work transfer during intake process: 25.6 J
Net Indicative work per cycle : J
Heat Input (J): J

9. Work Distribution Analysis of Conventional S. I
Work Distribution Analysis of Conventional S.I. Engine (Indicative) Cycle

10. The Problem
The problem is due to the fact, that the single reciprocating device has a compression stroke which is equal to the expansion stroke.
On one hand, you need a high expansion stroke in order to convert the maximum of thermal energy into work.
On the other hand, there is a limit on compression stroke, in order to limit the thermal and mechanical stresses, as well as the non controlled ignition for gasoline cycles.
This leads to the situation, that the four-stroke cycles should only be run with a rather small load pressure range (absolute load pressure = bar), with throttling for low loads.
“Don’t throttle the engine down, load it up!”

11. The Unreasonable Bias Intake Stroke Compression Power Exhaust FUEL A I
Combustion
Products
Ignition
Intake
Stroke
FUEL
Fuel/Air
Mixture
Compression
Power
Exhaust

12. In 2000, a new engine is born ...
Three cylinder 5-Stroke engine

13. CAD Model of Five Stroke Engine

14. Concept of modifications of design of the engine cylinder head
Four-stroke engine cylinde rhead
Engine cylinder head adapted to realize five-stroke cycle

15. The Five Stroke Cycle
The five-stroke cycle consists in the following steps: 1. Admission of air with PFI fuel in the high pressure (HP) cylinder 2. Compression, followed by the ignition. 3. First expansion of the burned gases LP cylinder while exhausting HO cylinder . 4. Second expansion of the burned gases in LP cylinder. 5. Exhausting of the burned gases from LP cylinder.

16. Phase A : Intake in Hp Cylinder 1, Expansion in HP 2 & Exhaust in LP

17. Phase B : Compression + Combustion in HP 1, Expansion in LP & Transfer from HP 2

18. Magnitude & Location of Peak Pressure

19. Phase C : Combustion + Expansion in HP 1, Intake in HP2 & Exhaust from LP

20. Phase D : Transfer from HP 1, Intake in HP 2 & Expansion in LP

21. Valve Lift Diagrams

22. Pressure Vs Crank Angle for HP & LP Cylinders

23. Work Delivered during Expansion in LP Cylinder

24. Pressure/Volume diagram of 5-stroke cycle at 4000 rpm : HP Cycles

25. Pressure/Volume diagram of 5-stroke cycle at 4000 rpm LP Cycles

26. BSFC of the 4- and 5-stroke engines at 4000 rpm

27. Net Work distribution at full load (100%)
Frictional Losses : ~ 5%

28. Fuel economy of the 5-stroke cycle vs. 4-stroke cycle
The 750 ccm five-stroke engine is designed to produce equivalent torque/power, i.e.
46kW/110Nm at 4000 rpm, than the 1200 ccm four-stroke engine.

29. Comparison of Performance Curves for five-stroke engine and four-stroke engine

30. The Model Five Stroke Engine
Number of cylinders: 3
Supercharged: Yes
Global piston displacement: 750 ccm
High pressure area (HP):
Number of cylinders: 2
Individual piston displacement: 150 ccm
Bore: 60 mm
Stroke: 53 mm
Compression ratio: 8:1
Number of intake valves: 1
Intake valve, diameter: 21 mm
Number of exhaust valves: 1
Exhaust/Transfer valve diameter: 21 mm

31. Low pressure area (LP):
Number of cylinders: 1
Individual piston displacement: 449 ccm
Bore: 83 mm
Stroke: 83 mm
Compression ratio: 7.7:1
Number of exhaust valves: 1
Exhaust valve diameter: 45 mm

32. Work Distribution Analysis of Five Stroke S. I
Work Distribution Analysis of Five Stroke S.I. Engine Indicative Cycle at Design Conditions : HP Cylinder
Work transfer during intake process: 51.3 J
Work transfer during compression process: J
Work transfer during Expansion process: J
Work transfer during Exhaust process: J
Net Indicative work per cycle : J

33. Work Distribution Analysis of Five Stroke S. I
Work Distribution Analysis of Five Stroke S.I. Engine Indicative Cycle at Design Conditions : LP Cylinder
Work transfer during Expansion process: J
Work transfer during Exhaust process: J
Net Indicative work per cycle : J
Total indicated work (J): 731.9
Heat Input (J):

34. Indicated work over two crank rotations in the 5-stroke engine

35. Energy Audit of Five stroke S. I
Energy Audit of Five stroke S.I. Engine Indicative Cycle at Design Conditions
Heat Input (J):
Total indicated work (J): & Cooling loss : J
Heat transfer density (W/cm²) at... HP LP
...cylinder head:
... piston upper face:
...cylinder wall:
...transfer pipe:
Effective torque (Nm): 109.9
Effective power (kW): 46.0
Thermodynamic efficiency (./.):
Mechanical efficiency (./.): 0.943
Global efficiency (./.): 0.436
BSFC (gr/kWh): 192.9

36. Work Distribution Analysis of Five Stroke Engine

37. Effective Work over one 5- and 4-stroke crank rotation