Question

A 4 stroke spark ignition engine gave the following results during a test. Number of cylinders 6 Bore of cylinders 90 mm Stroke 80 mm Speed 5000 rev/min Fuel consumption rate 0.3 dm/min Fuel density 750 kg/m Calorific value 44 MJ/kg Net brake load 180 N Torque arm 0.5 m Net indicated area 720 mm Base length of indicator diagram 60 mm Pressure scale 40 kPa/mm Calculate the following. The Brake Power. ii) The Mean effective Pressure. The Indicated Power. The Mechanical Efficiency. v) The Brake Thermal efficiency. (source: Very relevant questions on ICE.pdf] [47.12 kW, 480 kPa, 61 kW, 77.2%, 28.6 %] iv)

Answer 1

Cünen 4 stroke spark ignition engine No. of cylinders, k 6. Bore, d = 90 mm = 0.09 m vrea , A= (0.09) Stooke, l = 80mm = 0.08 m. speedlin) = 5000 rev/min. feel density :P= 750 kg/m3. colorific value, BCVE 44 MJ/ Net brake load = 180N: Torque o cum = 0.5m. Net indicated area = 720 mm? length of chagram, ly = 6omm. pressure scale, Pg= 40 kpa /mm.

c) Brake power BP = 277NT 60 = 2īT ( 5000)(180X 0.5) 60 = . 47.12 kW. cii) mean effective pressure Pim. = A d Ad vo = 720 x 40 60 = 480 kpa. IP ii) Andicated poween (IP) Pime Ank 60000 480 X103 x.0.08x T (0.093.000. 60000 4X2

na M ,K=6. 480 X 103 % 0.02% 11 (0.09) 75000XG 60,000 X 4X2 61.07 kW (iv) Mechanical, efficiency, mm = BP 47.12 61.07. n = 77.152 77.15% (V) Brake thermal efficiency: BP y = mpxcv. Voth mg = 0.3dm3/min. mf = 0.3 K103 m/min. mm = 0.3x10-8X 750 Kg/s. 60 mos 3.757 10-3 kg/s

11. ( x 10. 3.45 KID=3х цЧ Хов 22.557