Internal Combustion Engines

Question 1

Diesel cycle heat added, Qa

Answer 1

Qa = mCp(T3-T2)

Question 2

Diesel cycle heat rejected, Qr

Answer 2

Qr = mCv(T4-T1)

Question 3

Diesel cycle net work, Wnet

Answer 3

Wnet = Qa - Qr

Question 4

Diesel cycle compression ratio, rk

Answer 4

rk = V1/V2 = (1+c) / c

Question 5

Diesel cycle clearance ratio, c

Answer 5

c = V2/Vd = V2 / (V1-V2)
- Vd = piston volume displacement

Question 6

Diesel cycle cycle efficiency

Answer 6

Wnet/Qa = (Qa-Qr)/Qa

Question 7

Diesel cycle cycle efficiency given compression ratio and clearance ratio

Answer 7

1 - (1 / ( rk ^ k-1 )) [ (rc^k - 1) / ( k (rc-1) ) ]

Question 8

Brake power using brake mean effective pressure (Pmb)

Answer 8

Brake power = Pmb × Vd

Question 9

Piston volume displacement, Vd

Answer 9

Vd = (π/4)D²LNC m³/sec
-D = bore, m
-L = stroke length, m
-N = speed, rev/sec (for 2-stroke)
-N = speed / 2 , rev/sec (for 4-stroke)
-C = number of cylinders

Question 10

Otto cycle cycle efficiency using compression ratio

Answer 10

1 - 1/(rk ^ k-1)

Question 11

Otto cycle cycle efficiency

Answer 11

Wnet/Qa = Qa-Qr/Qa = (T3-T2)-(T4-T1) / (T3-T2)