Question

An engine has a swept volume of 275 \(\text{cm}^3\), clearance volume of 25 \(\text{cm}^3\). Its volumetric efficiency is 0.80 and mechanical efficiency is 0.90. The volume of mixture taken in per stroke is

• A. 200 \(\text{cm}^3\)
• B. 275 \(\text{cm}^3\)
• C. 220 \(\text{cm}^3\)
• D. 180 \(\text{cm}^3\)

Hint:

Volumetric efficiency compares the actual charge volume to the swept volume, not the total volume (swept + clearance). Hence, ignore the clearance volume and mechanical efficiency in this calculation.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Volumetric efficiency measures how effectively an engine cylinder draws in the charge during the intake stroke compared to its physical displacement limit.

Step 2: Key Formula or Approach:
Volumetric efficiency (\(\eta_v\)) is defined as:
\[ \eta_v = \frac{V_{\text{actual}}}{V_s} \] where:
\(V_{\text{actual}}\) = actual volume of the fresh mixture drawn in per stroke
\(V_s\) = swept (displacement) volume of the cylinder

Step 3: Detailed Explanation:
Given values:
- Swept Volume (\(V_s\)) = \(275 \text{ cm}^3\)
- Volumetric Efficiency (\(\eta_v\)) = \(0.80\)
- Mechanical Efficiency = \(0.90\) (This value is not required to calculate volume of intake mixture).
Now, calculate the actual volume of mixture taken in (\(V_{\text{actual}}\)):
\[ V_{\text{actual}} = \eta_v \times V_s \] \[ V_{\text{actual}} = 0.80 \times 275 \] \[ V_{\text{actual}} = 220 \text{ cm}^3 \]

Step 4: Final Answer:
The correct option is 3, which corresponds to 220 \(\text{cm}^3\).