Numericals (3) A single cylinder engine running at 180 rpm develops a torque of 8 Nm. The indicated power of the engine 1.8 kW. Find the loss due to friction power as the percentage of brake power. Ans: 19.37% of brake power. (4) A vertical single cylinder four stroke diesel engine has a bore = 80 mm and stroke = 100 mm respectively. It is water cooled and develops a torque of 3.5 N-m. Calculate the break mean effective pressure of the engine. Ans: 5.875 bar. (5) A diesel engine consumes 5 grams fuel per second and develops a brake power 75 kW. It has a mechanical efficiency of 85%. Find (a) Brake specific fuel consumption in kg/kWh, (b) Indicated specific fuel consumption in kg/kWh. Ans: bsfc = 0.24 kg/kWh, isfc = 0.204 kg/kWh
Numericals (6) The following readings are taken during a test of a four-cylinder, two stroke gasoline engine. Diameter = 10 cm, Stroke = 15 cm, Speed = 1700 rpm, Area of positive loop of the indicator diagram = 5.75 sq.cm; Area of the negative loop of the indicator diagram = 0.25 sq.cm; Length of indicator diagram = 5.5 cm, Spring constant = 4.0 bar/cm. Find the indicated power of the engine. Ans: I.P. = 53.38 kW. Note: Net area of the indicator diagram = Area of positive loop of the indicator diagram - Area of the negative loop of the indicator diagram
Numericals (7) A four stroke gas engine has a bore of 20 cm and stroke of 35 cm and runs at 400 rpm firing every cycle. The air-fuel ratio is 4 : 1 by volume. Its volumetric efficiency at NTP conditions is 80%, determine the volume of gas (mixture) used per minute. If the calorific value of the gas is 8 MJ/m 3 at NTP and the brake thermal efficiency is 25%. Determine brake power of engine. Ans: Volume of gas (mixture) used per minute = 0.25133 m 3 at NTP/min ,B.P. = 8.377 kW.
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