What is the difference between spark ignition and compression?

The Spark Ignition (SI) engine, as its name indicates uses spark to ignite the fuel. And in Compression Ignition (CI) engine, the air is compressed within the cylinder and the heat of this compression air is used to ignite the fuel.

Which is better spark ignition engine or compression ignition engine?

CI has more efficient than SI. CI produces more noise than SI when it works. CI produces more hydrocarbons at the exhaust stroke of the engine than SI engines. SI engine has a spark plug, but CI does not have one.

What are advantages of compression ignition over spark ignition?

CI engines have higher Thermodynamic Efficiency 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.

Why are compression ignition engines more efficient?

The petrol engine relies on a spark for ignition at lower compression. The higher compression ratio of the diesel engine means it has a high expansion ratio – the difference between the compressed space and the space opened up when the piston reaches the bottom of its travel. That equates to higher efficiency.

Why is it called a compression ignition engine?

Diesel engines are sometimes called compression-ignition engines because initiation of combustion relies on air heated by compression rather than on an electric spark. In a diesel engine, fuel is introduced as the piston approaches the top dead centre of its stroke.

What is efficiency of Otto cycle?

A typical gasoline automotive engine operates at around 25% to 30% of thermal efficiency. About 70-75% is rejected as waste heat without being converted into useful work, i.e., work delivered to wheels.

Why is it called a spark ignition engine?

The term spark-ignition engine refers to internal combustion engines, generally petrol engines, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug.

What are the disadvantages of CI engine?

Disadvantages:

• CI engines are higher in weight.
• These produces more vibration compare to SI engines.
• It creates unpleasant odour in exhaust.
• Higher cost.

What is the maximum compression ratio of spark ignition engine?

In Spark Ignition engines, the spark serves to ignite only if (a) the temperature is below the ignition temperature, or (b) the fuel isn’t present in the cylinder (yet). The maximum compression ratio in spark ignition engines is 12.

Which engine is compression ignition?

The compression ignition engine or diesel engine is the type that has most commonly been used for power generation, particularly in off-grid situations. The engine uses a higher compression ratio than a spark ignition engine to heat air in the engine cylinder.

What are spark ignition engine used for?

1 Spark-Ignition Engine. The spark-ignition engine (Fig. 20A) is the universal engine for all fuels of low inflammability, especially gasoline (a mixture of several hydrocarbons), but also liquefied petroleum gas (LPG), liquefied natural gas (LNG), methanol and ethanol (alcohols), and hydrogen.

Why is Otto more efficient than Diesel?

Although for a given compression ratio the Otto cycle has higher efficiency, because the Diesel engine can be operated to higher compression ratio, the engine can actually have higher efficiency than an Otto cycle when both are operated at compression ratios that might be achieved in practice.