MINI PROJECT ON MAINTENANCE OF VARIABLE COMPRESSION RATIO ENGINE
Jan 20, 2015
MINI PROJECT ON
MAINTENANCE OF VARIABLE COMPRESSION RATIO ENGINE
ARUN BABUARUN THANKACHANASHIK SAHADEVAN
GUIDED BY Dr. SUDHIR KUMAR . R
PROJECT TEAM
Variable Compression EngineTheoryOur WorkExperiment & ResultConclusion
CONTENTS
What is it?
Is the ratio by which the fuel/air mixture is compressed before it is ignited
Limited in conventional engines due to auto-ignition.
Determines how efficiently the engine can utilize the energy in the fuel
Compression Ratio (CR)
CR – How is it determined?
volcylinder
volcylinderCR
min
max
-or-
Where b=cylinder bore (diameter) s = piston stroke lengthVc = Clearance volume
For an ideal Otto cycle the theoretical efficiency is given by,
Where r is the compression ratio and γ is the ratio of specific heats. For an SI-engine operating at stoichiometric mixture γ=1:3.
Theoretically, increasing the compression ratio of an engine can improve the thermal efficiency of the engine by producing more power output.
If the compression ratio is too high, the air/fuel mixture are exposed to higher temperatures, the fuel will auto ignite, giving rise to knocking, which could damage the engine.
Increased Efficiency and Pollution Reduction with VCR:
VCR - advantages
CR modified to meet power demand (CR’s range from 7:1 to 21:1)
Increased fuel efficiency Claims of up to 30% reduction in fuel
consumption Adding variable valve actuation and turbo-
charging further improves fuel efficiency (7-10% additional reduction in fuel consumption)
Reduced combustion emissions
VCR - Disadvantages
New technology results in high research and development and manufacturing costs.
Reliability is not proven. Consumer reactions are unknown
and unpredictable. Repairs and maintenance initially
may be difficult and costly.
Ways to Modify CR
Moving the cylinder head. Variation of combustion chamber volume. Variation of piston deck height. Modification of connecting rod geometry. Moving the crankpin within the
crankshaft (effectively varying the stroke).
Moving the crankshaft axis.
Ways to Modify CR:
A: articulated cylinder head
B: hydraulic pistons
C: eccentrics on bearings
D: multilink rod-crank mechanisms
E: additional piston in cylinder head
F: gear-based mechanisms
OUR WORK
VARIABLE COMPRESSION RATIO ENGINE TEST RIG
SPECIFICATIONS FOUR STROKE,SINGLE
CYLINDER,VERTICALLY MOUNTED PETROL ENGINE
BRAKE POWER : 2.20 kW SPEED : 2000rpm STROKE : 66.7 mm BORE : 70 mm ORIFICE DIA : 20 mm
FAULT DETECTION
We find out the following components were not in working condition1. Spark Plug2. Condenser3. Contact Switch4. Scale showing Compression Ratio5. Cooling Water Pipe6. Fuel pipe
CHANGING COMPRESSION RATIO
EXPERIMENT
Note down the time taken for 10cc fuel consumption by varying CR(at 2000 rpm)
At load we conduct the same experiment ,ie note down the time taken for 10cc fuel consumption by varying CR( at 2000 rpm, 110 v and 3 Ampere)
CHARACTERISTICS
Conclusions
Variable Compression Ratio engines have great potential to increase engine power and fuel economy.
When coupled with technologies such as turbocharging, variable valve actuation, and direct fuel injection, the effectiveness of the system is further increased.
Once established, this technology will likely become commonplace due to increasing energy and environmental concerns and the ease of integration.
THANK YOU