Mechanical Engineering - IC Engines and Nuclear Power Plants - Discussion

I think B is the right answer.

Petrol engine as compared to a diesel engine has a lower compression ratio. If the autoignition temp of petrol is higher than diesel then why is the compression ratio of petrol engines lower than diesel engines?

According to this question (B) is the right answer.

Option C is correct.

Self-ignition temperature of petrol is 247"280°C.
Self-ignition temperature of diesel is around 210°C.

So as seen, diesel has low self ignition temperature, and that's why diesel engine doesn't have a spark plug.

In the gasoline, petrol engine self-ignition temp is low when compared with diesel engines because if petrol has high ignition temp then no need for spark plugs right.

B is the right answer because petrol is high volatile fuel.

I think B is right.

The Branching habit and tendency to form intermolecular bonds reduce with the growth of chain length in alkanes as per the fact that the Gibbs Free Energy is lowered with increasing molecular weight. So, diesel having higher chain length will have a lower tendency for branching and hence break easily due to the application of heat as compared to petrol. Hence we can correctly assume the correct answer is C. And petrol will have higher autoignition temperature than that of diesel.

The Self Ignition auto-ignition temperature is the lowest temperature at which a fuel such as petrol or diesel spontaneously ignites in a normal atmosphere without an external source of ignition, such as a flame or spark.

Self-ignition temperature of petrol is 247-280°C.
Self-ignition temperature of diesel is around 210°C.
So as seen, diesel has low self-ignition temperature, and that's why diesel engine doesn't have a spark plug

For a comparison, the substance like white phosphorus will catch fire as low of 34°C.

The right answer is B.