Question

A gasoline engine of 6 cylinders operates on the four-stroke cycle. The bore of each cylinder is 80 mm and the stroke is 100 mm. The indicator diagram shows an indicated mean effective pressure of 7.3 bars. The clearance volume (Vmin) of the engine is 420 cm². At the speed of 4100 rpm, the fuel consumption is 19.8 kg/hr and the torque developed is 160 Nm. Calculate: (a) Brake power (2 mark) (b) The brake mean effective pressure, (1 mark) (c) Friction losses (2 marks) (d) Brake thermal efficiency if the heat (calorific) value of the fuel is 44000 kJ/kg (1 marks) (e) The thermal efficiency assuming the engine works on air standard Otto cycle (K = 1.4 for air. (2 marks) (f) During the test, (C10H22) is burnt using an air-fuel ratio of 13:1 by weight. Determine the complete volumetric analysis of the products of combustion, if the whole amount of hydrogen burns to form water vapour and there is neither any free oxygen nor any free carbon. The carbon burns to CO2 and CO. (5 marks)

Answer 1

Grisan Given # Bore of cach 7.3 bar प 19.8 3600 Gasoline Engine [ Petrol Engine] 6 cylinder operatus on the four-stroke cycle. cylinder D = 80 mm. stroke of each cylindes 2 = 100 mm Indicated Mean effective pressure Pimep clearance Volume of the Engine = 420 cm speed of Engine N = 4100 rpm fuel consumption in kg/s Torque developed T = 160 Nm (a.) Brake Power know Brake Power BP = Txw 160 x 27 x 4100 -BP 60 Brake Power BP 68.696 kW (6) The Brake Mean Effentine Pressure Pempt is BP & x²xNxk : 68.69615(kW 2x60 bop ( 1.0.02?x0:4.x400,0) = 68696.15 we . Pimep ( Pomimap - 6.6667 bar The Brake Mean effective Pressure = 6.667 bar CS Scanned with CamScanner

(9) frictwo losses Indicated Power & Pimpa Us 1.2 - 73 xró [Bu dak] kW 120 E 7:3 x20? * x 0.08? x 0.1 y 4100x6 4 120 75: 22 kW . . Frictws Power Loss IP. - B:P Indicated Power - Brake Power 75.22-68. 696 6.526 kW (a] Brake Thermal efficiency if the heat I calorific value of the ful scy : 49000 19/kg kolleg -Brake Power Ebith Meat supplied ng 68.696 3-100 119.8 --44000) hs, the = 28.387 % BP Mbith XCV . 3600 Brake Thurnal efficiency 28.387 % Am CS Scanned with CamScanner

Thure thermal efficiency Assunning the Engine works on fir standard olto cycle. tk: 1.4 for Air we know I The ratio compression rolt to clearance Ratio - 1 30.1392-6 6x10 dalt 420 V -Vउ こ Yolgab Elt! 8-181 0.4-1 10.4 how (8.181) 0.5686 (8.181) 1) 56.86_4. -Thermal a effica iney assuming engine works. on fir standard how 56.86% VD Mence, the otto yle CS Scanned with CamScanner