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 Nm. 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
fourcylinder, 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 airfuel
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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 Winter '15
 Sundararajan
 Thermodynamics, Power, Internal combustion engine, Diesel engine, brake power, heat balance sheet