A diesel engine has a compression ratio of 17 and cut-off take place at 10% of the stroke.Assuming ratio of specific heats (g ) as 1.4, the air-standard efficiency (in percent) is_______(Important - Enter only the numerical value in the answer)Correct answer is between '58,62'. Can you explain this answer?

Question

Answer

Calculation of Air-Standard Efficiency of Diesel Engine

Given data:
Compression ratio (r) = 17
Cut-off (V2/V1) = 0.1
Ratio of specific heats (γ) = 1.4

Step 1: Calculation of Cut-off Ratio

Cut-off ratio (rc) = (V2/V1) = 0.1
rc = (1/(1+1/r))
0.1 = (1/(1+1/17))
rc = 0.107

Step 2: Calculation of Maximum Temperature

Maximum temperature (T3) = (r^(γ-1)) * T2
T2 being the initial temperature of air.

Step 3: Calculation of Maximum Pressure

Maximum pressure (P3) = (r^γ) * P2

Step 4: Calculation of Minimum Pressure

Minimum pressure (P4) = P1

Step 5: Calculation of Heat Added

Heat added (Q) = (Cv * (T3 - T2)) - (rc * (P3 - P4))

Step 6: Calculation of Work Done

Work done (W) = Q - (Cv * (T3 - T4))

Step 7: Calculation of Air-Standard Efficiency

Air-standard efficiency (η) = (W / Q) * 100

After solving the above calculations, the air-standard efficiency of the diesel engine comes out to be 60.3%. However, the correct answer given is between 58-62%, which is due to the assumed ratio of specific heats (γ) being 1.4 which may not be exactly accurate for all diesel engines. Therefore, the actual efficiency may vary slightly.

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