Question
Download Solution PDFStatement (I): To prevent knocking in SI engines the end gas should have a low density.
Statement (II): Pre-ignition is caused due to detonation.Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
For Statement 1:
- To prevent knock in SI engine the end gas should have low temperature, pressure and density, a long ignition delay and a non-reactive composition. If the density of the end gas is less, then the pressure and temperature of the end gas do not rise to achieve the ignition temperature as a result of which the auto-ignition cannot take place and the chance of detonation gets reduced.
For Statement 2:
Auto ignition:
- A mixture of fuel and air can react spontaneously and produce heat by chemical reaction in the absence of flame to initiate the combustion or self-ignition.
- This type of self-ignition in the absence of flame is known as Auto-Ignition. The temperature at which the self-ignition takes place is known as self-igniting temperature.
- The pressure and temperature abruptly increase due to auto-ignition because of sudden release of chemical energy. This auto-ignition leads to abnormal combustion known as detonation.
⇒ The statement 2 is false and statement 1 is true
Last updated on Jul 2, 2025
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