With a higher compression ratio in CI engines as compared to SI engines, CI engines have a higher thermodynamic efficiency since more work is done with each expansion stroke.
Which is better Si or CI?
The high temperatures achieved in CI engines cause the fuel to ignite. SI engines are high speed while CI engines are low speed. SI engines have a lower thermal efficiency than CI engines.
Is CI engine more efficient than SI engine?
CI engines achieve higher efficiencies than SI engines, peaking around 45% (US DOE, 2010). Load is controlled in a CI engine by the amount of fuel injected limited by the amount of charge gas oxygen.
Why is it more beneficial in a CI engine compared to an SI engine?
It has high compression ratio because of the high ignition temperature of the diesel fuel. The heat of the compressed air ignites the fuel. Due to the high compression ratio it produces more power. … The maintenance cost of the CI engine is more as compared with the SI engines.
Why are CI engines more efficient?
Diesel engines are more efficient than gasoline engines for two reasons: (i) higher cylinder pressures and corresponding higher temperatures lead to improved thermal efficiency for the diesel engine; (ii) the air throttling required to control the gasoline engine power output reduces engine efficiency and is not used …
What does SI and CI engine mean?
Definition of Si engine and Ci engine
Si engine is internal combustion engine that operates on the principle of spark ignition. It uses petrol and utilizes the Otto cycle. The diesel (Ci) engine is also an internal combustion engine, which uses diesel fuel and operates on diesel cycle.
Why diesel engines are called CI engines?
Diesel engines are sometimes called compression-ignition engines because initiation of combustion relies on air heated by compression rather than on an electric spark. … As the piston moves away from this position, fuel injection is continued, and the combustion process then appears as a nearly constant-pressure process.
Which is not use in CI engine?
Why methanol is not used in CI engine? Explanation: Methanol is not used in CI engines because of its high octane number and low cetane number. Pure methanol and gasoline in various percentages have been extensively tested in engines and vehicles for a number of years.
Is fuel pump used in CI engine?
The injection pump sends fuel under pressure to the nozzle pipes which carry fuel to the injector nozzles located in each cylinder head. Excess fuel goes back to the fuel tank. CI engines are operated unthrottled, with engine speed and power controlled by the amount of fuel injected during each cycle.
What are the advantages of SI engine?
Advantages Of SI Engine:
- SI Engines are low in cost.
- SI Engine produces less pollution as compared to CI Engine.
- These engines are smaller as compared to CI engine and hence requires less space.
- These engines are lightweight.
- The cost of an SI engine is lower as compared to CI Engine.
Why CI engine is heavier than SI engine?
Weight of the engines: In CI engines the compression ratio is higher, which produces high pressures inside the engine. Hence CI engines are heavier than SI engines.
What are the fundamental differences between SI and CI engines?
Now Let’s See the Difference Between SI and CI Engine:
|SI Engine||CI Engine|
|The compression ratio is 6 to 10. The upper limit is fixed by the antiknock quality of the fuel.||The compression ratio is 16 to 20. The upper limit is limited by the weight increase of the engine.|
Why do we not use the same technology to start both SI and CI engines?
So in case of SI engine, the compression ratio is not sufficient for fuel to burn so a spark plug is used, whereas in ci engine, the compression ratio is so high that due to its internal heat the fuel is combusted so there is no need for a spark plug. So the technology used in SI engine is different from CI engine.