Question

A six cylinder, four-stroke diesel engine develops 125 kW at 3000 rpm. Its brake specific fuel consumption is 200gm/kW h. Calculate the quantity of fuel to be injected per cycle per cylinder. Specific gravity of the fuel may be taken as 0.85.

(a) 0.0545 cc/cycle

(b) 0.545 cc/ cycle

(c) 5.45 cc/cycle

(d) none of the mentioned

The question was asked in a national level competition.

My query is from Injection Systems in division Mechanical Injection Systems of IC Engine

Answer 1

The correct option is (a) 0.0545 cc/cycle

The best I can explain: Fuel consumed/hour = bsfc x Power output

                                = 200 x 10^-2 x 125 = 25 kg

             Fuel consumption/cylinder = 25/6 = 4.17 kg/h

             Fuel consumption/cycle = (Fuel consumption/minute)/n

             where n = N/2 for four-stroke cycle engines = (4.17/60)/(3000/2)

                                                         = 4.63 x 10^-5 kg

                                                         = 0.0463 gm

             Volume of fuel injected = 0.0463/0.85

                                     = 0.0545 cc/cycle.