Variable compression ratio engine
- 2. ARUN BABU ARUN THANKACHAN ASHIK SAHADEVAN GUIDED BY Dr. SUDHIR KUMAR . R
- 3. Variable Compression Engine Theory Our Work Experiment & Result Conclusion
- 4. 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)
- 5. CR – How is it determined? volcylinder volcylinder CR min max -or- Where b=cylinder bore (diameter) s = piston stroke length Vc = Clearance volume
- 6. 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.
- 7. Increased Efficiency and Pollution Reduction with VCR:
- 8. 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
- 9. 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.
- 10. 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.
- 11. 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
- 12. 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
- 13. FAULT DETECTION We find out the following components were not in working condition 1. Spark Plug 2. Condenser 3. Contact Switch 4. Scale showing Compression Ratio 5. Cooling Water Pipe 6. Fuel pipe
- 15. 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)
- 16. CHARACTERISTICS
- 18. 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.