Question

Calculate the percentage loss in the ideal efficiency of a diesel engine with compression ratio 14 if the fuel cut-off is delayed from 5% to 8%.

Answer 1

Let the clearance volume (V₂) be unity. 

Then, compression ratio, r = 14 

Now, when the fuel is cut off at 5%, we have

= 1 – 0.248 × 1.563 = 0.612 or 61.2%

When the fuel is cut-off at 8%, we have

= 1 – 0.248 × 1.647 = 0.591 or 59.1%. 

Hence percentage loss in efficiency due to delay in fuel cut off 

= 61.2 – 59.1 = 2.1%.