Question

Which of the following option is correct when diesel is compared to petrol?

(a) highly ignitable

(b) more difficult to ignite

(c) less difficult to ignite

(d) none of the mentioned

The question was posed to me in an international level competition.

This interesting question is from Comparison of Two Stroke S.I. and C.I. Engines in division Two Stroke Engines of IC Engine

Answer 1

The correct answer is:

(b) more difficult to ignite

Explanation:

Diesel fuel is more difficult to ignite compared to petrol due to the following reasons:

1. Ignition Method: Diesel engines operate on compression ignition, where the fuel is injected into highly compressed, heated air and ignites due to the high temperature. This requires a higher ignition temperature and pressure.

2. Energy Density and Volatility: Diesel has a higher energy density than petrol but is less volatile. Petrol is more volatile, meaning it vaporizes and ignites more easily at lower temperatures and pressures, which is why it's used in spark ignition engines.

Thus, diesel is more difficult to ignite than petrol due to its higher ignition temperature and lower volatility.