7. the compression ratio in petrol engine is kept less than in diesel engine because
Answers
Answered by
0
Petrol engines are spark ignition engines and petrol burns quickly as compared to diesel because it is more volatile in nature and it also has a low octane number (in regular petrol).So if more compression is given it may result into knocking of the engine so petrol engines have a low compression ratio.
From the above image you can easily deduce that as the Compression Ratio(CR) increases, the efficiency of otto cycle increases too. But the question arises, why the compression ratio of Petrol engines is kept low (between 6 to 10) as compared to Diesel engines ( between 16 to 20).
Firstly, more the compression ratio, more is the chances of Knocking (which is an unwanted phenomena).
In petrol engines, during suction stroke, both air and fuel enters into the cylinder. So if CR is kept higher, the fuel might burn soon. But in Diesel engines only air is entered during suction stroke so there is no such problem.
From the above image you can easily deduce that as the Compression Ratio(CR) increases, the efficiency of otto cycle increases too. But the question arises, why the compression ratio of Petrol engines is kept low (between 6 to 10) as compared to Diesel engines ( between 16 to 20).
Firstly, more the compression ratio, more is the chances of Knocking (which is an unwanted phenomena).
In petrol engines, during suction stroke, both air and fuel enters into the cylinder. So if CR is kept higher, the fuel might burn soon. But in Diesel engines only air is entered during suction stroke so there is no such problem.
Similar questions