Question

A 4-stroke 3 litre V6 spark ignition petrol engine has a maximum power output of 100kW at 5500rev/min, and a maximum torque of 236Nm at 3000rev/min. The minimum sfc is 0.090 kg/MJ at 3000 rpm, and the air flow rate is 0.068m²/s. The compression ratio is 8.9:1 and the mechanical efficiency is 90%. The engine was tested under ambient conditions of 20°C and 1 bar. Take the calorific value of fuel to be 44MJ/kg. (a) Determine the power output at 3000rpm and the torque output at 5500rpm. (74.1 kW, 173.6 Nm) (b) For both speeds calculate the bmep and the imep. (9.89bar, 7.27bar, 10.99bar, 8.08bar) compare with the (c) How does the arbitrary overall efficiency at 3000rpm corresponding air standard Otto cycle efficiency? (25.25%, 58.3%) (d) What is the volumetric efficiency and air/fuel ratio at 3000rpm? (90.7%, 12:1)

Answer 1

ANSWER:

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Given that: maximum power output of 100kw at 5500 verimin maximum torque of 236 Nm at 3000 rev/min . The minimum she is 0.090 kglmy at 3000rpm, air flow rate is 0.068 m3/ compression ratio is 8.951. mechanical efficiency is 90%, ambient conditions of 20°c and bar. the calorific value of fuel to be 44 milky. la Nz 3000 rpm T = 236 Nm power a (2007) - 2x x 3000 x 236 kw , ? 60x 1000 Power = 74.14 kwt Në 5500 rpm, P=100kw 25 NXT 100x103W . 60 .

20 x 5500 XT = 100x10²w' 60 T = 173 .62arm) (6) for a = 3000 rpm B.P. 74.14 Kw : va 3x10?me mebp X VXC ). ep. 60 PGPA 3X10 3 (3000) = 74.14 Kw · . .60 . Pop = 998 .53kpai 1601P(89) 59.8853 bar I.P = (BP] 94.14 -82-371kw. -3. PT Рx 3х10 20 2.) - 82-877. 60 . PIP = 1097-778 kPa (0) PIP = 10.977 bar Now speed changed to 5500 Rpm ,

BP = 100kW POPX 3x10x5500 100kw 60 2 . / 100 x BMEP a 120 ( 31109x5500 BMEP = 727.27 kPa. on BMEP = 7.2727 bas I.P = BP (100 kw non IP = Ill.lllkw zmép x 3x1024 ( 9600 )= (100) 60 IMER 808 kPa con IMEP = 8:08 bar (6) N= 3000 RPM. IP = 174.1kw = 82 .333 kw inf. (B.p) bific kg: in f = 74 x 0.90 kg 1000 imf = 6.0669x103 rols.

Heat supplied alm fx.cv) 26.689 x103 x 44 x103 - 293.436 kwi na = I. P 1 a 32:33 X 100 293.436 28.0577, Rotho (- ). (tagalogies) 3,00 58.287. . (d) NNE Actual volume volume Ideal - volume Ideally, Actual volume = 0.068 m3/s. volume displace = ( a 20 x ( A ) ) a/s. . | SKIDB x 45000 m/s L60 2 : -0.015 im lg. 0.068 on? 0.075 ml x 100 nr. 2. +90.67%

Prema X RT, - 100 x .068 a mar 2870 (27.3 otto) m a 0-0808647 kg Is. AF = 0.0808647. 6.666810 3 kals. - 12:1