The knocking tendency of a fuel in S. I. engines is generally expressed by its octane number. … Thus, if a mixture of 50 percent iso-octane and 50 percent normal heptane matches the fuel under test, then this fuel is assigned an octane number rating of 50.
How SI and CI engine fuels are rated?
An unknown fuel sample is tested on the basis of reference or standard fuel whose octane and cetane number is known. Octane number is considered for SI engine while Cetane number is considered for CI engine. They are calculated through comparison by perfect fuel characteristics.
Which of the following is the best fuel for SI engine?
So, ethanol has been used widely as alternative fuel in internal combustion engines. The octane number of ethanol is higher than the octane number of the gasoline. The high octane number of ethanol allows the use of ethanol as fuel in an SI engine with a higher compression ratio .
What is the measure of rating of SI engine?
The octane rating is a measure of the resistance of gasoline and other fuels to detonation (engine knocking) in spark-ignition internal combustion engines. High-performance engines typically have higher compression ratios and are therefore more prone to detonation, so they require higher octane fuel.
Which fuel is not suitable for SI engine?
However, these terms are not preferred, since spark-ignition engines can (and increasingly are) run on fuels other than petrol/gasoline, such as autogas (LPG), methanol, ethanol, bioethanol, compressed natural gas (CNG), hydrogen, and (in drag racing) nitromethane.
What are the various alternative fuels for SI and CI engines?
The most common alternative fuels for SI engines are ethanol in blends with gasoline as well as compressed natural gas (CNG) , liquefied natural gas (LNG) , and liquefied petroleum gas (LPG) . Biodiesel, synthetic diesel, green diesel, and DME are the most common alternative fuels for CI engines.
Which fuel is used in CI engine?
ICEs are typically powered by fossil fuels like natural gas or petroleum products such as gasoline, diesel fuel or fuel oil. Renewable fuels like biodiesel are used in compression ignition(CI) engines and bioethanol or ETBE (ethyl tert-butyl ether) produced from bioethanol in spark ignition(SI) engines.
What is the meaning of SI engine?
Definition English: 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.
Why hydrogen is not used as a fuel?
Hydrogen has the highest calorific value so it can be considered as the best fuel but it is highly inflammable so it is diificult to store, transport and handle so it is used as a fuel only where it is absolutely necessary.
What is the working cycle of SI engine?
The cycle includes four distinct processes: intake, compression, combustion and power stroke, and exhaust. Spark ignition gasoline and compression ignition diesel engines differ in how they supply and ignite the fuel.
Why are 90 octane fuels better for engines than 85 octane fuels?
For most vehicles, higher octane fuel may improve performance and gas mileage and reduce carbon dioxide (CO2) emissions by a few percent during severe duty operation, such as towing a trailer or carrying heavy loads, especially in hot weather.
What are the effects of knocking in SI engine?
The usage of hydrogen in compression ignition engine leads to production of knocking or detonation because of its lower ignition energy, wider flammability range, and shorter quenching distance. Knocking combustion causes major engine damage, and also reduces the efficiency.
What is SI and CI engine?
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.
Who invented SI engine?
Its name comes from the German engineer Rudolf Diesel (1858−1913) who in 1892 described in his patent a form of internal combustion engine which does not require an external source of ignition and where combustion is initiated by the autoignition of the liquid fuel injected into the high temperature and pressure air …
Can a petrol engine run on hydrogen?
There are two types of hydrogen engines. … Say you have a petrol vehicle and convert it to run on hydrogen, your vehicle will still be able to run on petrol. This means you will be able to fill up your vehicle with hydrogen and when your vehicle runs out of hydrogen, you just swap back to petrol fuel.
Why diesel is not used in petrol engine?
We know that, petrol is ignited by spark and diesel is ignited by compression ignition, the volatility of the petrol is greater than diesel. The spark plug produces the spark only at some places, not at all the point of air-fuel mixture. … This is the reason for Why diesel cannot be used in petrol engine?.