This document discusses methods for improving engine performance, including through artificially aspirated engines. It analyzes parameters like indicated work, specific fuel consumption, indicated mean effective pressure, and fuel-air ratios. The document suggests that engines are most efficient near peak load and that artificial breathing attachments can help overcome the necessary design compromise between engine size and efficiency. It proposes turbocharging as an effective artificial respiratory system for engines through the inclusion of two pure control volumes.

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