Mechanical Engineering - Thermodynamics - Discussion

Discussion Forum : Thermodynamics - Section 1 (Q.No. 15)
15.
The compression ratio for petrol engines is
3 to 6
5 to 8
15 to 20
20 to 30
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
31 comments Page 2 of 4.

Jimmy said:   8 years ago
Both knocking and detonation are the same term. In the case of petrol engine, it occurs due to pre-ignition. Due to some reason temperature of fuel become self-ignite temperature, so it generates flame before spark plug ignites. Now, when spark plug ignites, there will be 2 flames inside the cylinder and when they collide knocking sound occurs.

Shivram sahu said:   8 years ago
Please, anybody explain the difference between detonation and knocking.

Amaan said:   9 years ago
But nowaday, Most of the petrol engine comes with injector. And spark plug doesn't use in it. Why?

And I know petrol have low ignition temperature so how can we ignite it by compression in this type of petrol engine?

Prince said:   9 years ago
Compression ratio for SI engine is 16 : 1.

Vishal said:   9 years ago
Spark plug use in petrol engine because we can not burn petrol by compression or pressure in a petrol engine is much lower than diesel engine it's about to 8 to 10 bar but in diesel engine, it becomes up to 18 to 20 bar.

Abubakkar.a said:   9 years ago
Anyone can explain about why we are using spark plug in a petrol engine?

Madhurya Daimari said:   1 decade ago
This range is used because if more compression is used there is the possibility of occurrence of knocking which can affect the system adversely.

Noor said:   10 years ago
The compression ratio of petrol engine is 6-10 and compression ratio of diesel engine is 15-22. Always should take nearer value. So 'B' is nearest Answer.

Rahul shah said:   10 years ago
Petrol & diesel both viscosity difference, its calorific value also different.

Ramjan said:   1 decade ago
Sir different between diesel and petrol.


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