work distribution analysis of i.c. engine cycles
TRANSCRIPT
Work Distribution Analysis of I.C. Engine Cycles
P M V SubbaraoProfessor
Mechanical Engineering Department
Find true Scope for Development….
BSFC of the 4- and 5-stroke engines at 4000 rpm
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.
The Model Four Stroke Engine
Number of cylinders: 4Supercharged: NoGlobal piston displacement: 1202 ccIndividual piston displacement: 300.5 ccBore: 72.6 mmStroke: 72.6 mmCompression ratio: 10:1Number of intake valves: 1Intake valve, diameter: 26 mmNumber of exhaust valves: 1Exhaust valve diameter: 26 mm
Work Distribution Analysis of Conventional S.I. Engine Indicative Cycle at Design Conditions
• Work transfer during intake process: 25.6 J• Work transfer during compression process: -102.7 J • Work transfer during Expansion process: 487.9 J• Work transfer during Exhaust process: -37.6 J• Net Indicative work per cycle : 373.2 J• Heat Input (J): 943.0 J
Energy Audit of Conventional S.I. Engine Indicative Cycle at Design Conditions
• Net Indicative work per cycle : 373.2 J• Heat Input (J): 943.0 J & Total cooling loss -187.3 J• Heat transfer density (W/cm²) at...• ...cylinder head: -45.168• ... piston upper face: -42.378• ...cylinder wall: -14.228• Effective torque (Nm): 110.0• Effective power (kW): 46.1• Thermodynamic efficiency (./.): 0.39577• Mechanical efficiency (./.): 0.926• Global efficiency (./.): 0.366• BSFC (gr/kWh): 229.6
Work Distribution Analysis of Conventional S.I. Engine (Indicative) Cycle
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
• 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
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: -158.4 J • Work transfer during Expansion process: 732.7 J• Work transfer during Exhaust process: -94.2 J• Net Indicative work per cycle : 531.5 J
Work Distribution Analysis of Five Stroke S.I. Engine Indicative Cycle at Design Conditions : LP
Cylinder • Work transfer during Expansion process: 348.2 J• Work transfer during Exhaust process: -147.5J• Net Indicative work per cycle : 200.3 J• Total indicated work (J): 731.9• Heat Input (J): 1582.8
Indicated work over two crank rotations in the 5-stroke engine
Energy Audit of Five stroke S.I. Engine Indicative Cycle at Design Conditions
• Heat Input (J): 1582.82500• Total indicated work (J): 731.8 & Cooling loss : -224.15 J• Heat transfer density (W/cm²) at... HP LP• ...cylinder head: -90.776 -43.084• ... piston upper face: -85.358 -39.329• ...cylinder wall: -38.029 -24.398• ...transfer pipe: -24.342• Effective torque (Nm): 109.9• Effective power (kW): 46.0• Thermodynamic efficiency (./.): 0.46239• Mechanical efficiency (./.): 0.943• Global efficiency (./.): 0.436• BSFC (gr/kWh): 192.9
Work Distribution Analysis of Five Stroke Engine
Effective Work over one 5- and 4-stroke crank rotation
Net Work distribution at full load (100%)
Frictional Losses : ~ 5%
More Strategies to Achieve Maximum Work
Output….
A Six Stroke Cycle with Water Injection
Schematic of typical intake & exhaust valve events for the six-stroke engine cycle.
Actual Scope for Expansion Process
Pressure Profile During Partial Compression of Exhaust
ddRTm
ddVp
RC
dQ
VCR
ddp mixmixmix
mix
vloss
v
mix21
1
wmixloss TThAdQ
8.08.02.02.3 mixUpDh
pmix SU 28.2
22 sincoscos11
211
aeRRr
VV
cc
22 sincos11211 RRr
VV
cc
Work Consumed by Exhaust Compression Process
dVpW
TDC
EVC
TDC
EVC
dVpWW nogenncompressio
,
Instantaneous Water Injection