ic engine performance

1. Analysis of Engine Performance
P M V Subbarao
Professor
Mechanical Engineering Department
How to Achieve higher Performance?

2. James Watts Solution

3. Cycle Performance Parameters
Net Work Transfer :

 )
(mv
pd
Wnet
This is work done by working fluid on the piston, also called as
Indicated Work.
Indicative Performance:
CV
m
mv
pd
f
ind


 )
(


4. I.C. Engine Test Rig

5. Specific Fuel Consumption
X
f
P
m
XSFC


 XSFC – specific fuel consumption (kg/kWh).
 X must always be specified when reporting these
values (i.e., I for indicated)
Fuel consumption of an engine reported in L/h or kg/h because
these values ignore engine power. A better measure of fuel
consumption is,

6. Specific Fuel Consumption Variations
• ISFC – indicated specific fuel consumption
• BSFC - brake specific fuel consumption
• PSFC – PTO specific fuel consumption
• DSFC – drawbar specific fuel consumption

7. Indicative Mean Effective Pressure:
min
max v
v
pdv
IMEP



Actual Fuel- Air Ratio :
act
air
fuel
act m
m
A
F
,









Stoichiometric Fuel- Air Ratio :
sto
air
fuel
sto m
m
A
F
,









Parameters for Performance Diagnosis
Fuel Air Equivalence Ratio:
sto
act
A
F
A
F















8. Selection of Mixture Strength for Better Reaction -1
Air-standard Analysis
Experimental Results
Fuel-Air Analysis
Rich
Lean

9. Selection of Sufficient Air : Optimization of Total
Cost
9

10. Combined Thermodynamic & Chemical
Optimization for Better Reaction -2
r = 8
r = 10

11. Combined Thermodynamic & Kinetic Optimization
for Better Reaction -2

12. Engine Capacity Vs Performance

13. Optimizing Engine Performance
• Engines are most efficient at or near peak load.
• Efficiency drops with a reduction in torque load.
• At zero brake torque, all fuel energy is expended in engine
friction.
• Lower rated engine speeds provide lower BSFC, and at the
same time reduce torque reserve – design compromise.
• Heavy engines for a given capacity….. More inertial losses…
• Compromise – Necessary Evil …..
• Any alternate to overcome this fact…..
• Develop an idea to Change natural behaviour…..

14. Artificial Breathing Attachments to Engines
Preferred Artificial Breathing ….

15. Engine Artificial Respiratory System
Super Charged Engine
An Inclusion of A Pure CV

16. Turbo Charging of Engine : An Inclusion of two PURE
CVs
Turbo-Charged Engine

17. Artificially Aspirated Engines

18. Characteristics of Artificially Charged Engines