Problem No. 4
The following results were obtained during a test on a two-cylinder four-stroke cycle IC engine over a period
of one hour.
Cylinder diameter, 108 mm
Piston stroke, 135 mm
Speed, 16.5 rps
Brake torque, 90 (N.m)
Fuel consumption, 2.5 kg
Calorific value of fuel, 45,500 (kJ/kg)
Mechanical efficiency, 62%;
The exhaust gases on leaving the cylinders were passed through an exhaust gas calorimeter and raised the
temperature of 215 kg of water from 15 °C to 61°C.
Specific heat capacity of water, 4.18 kJ/(kg.º C)
Determine:
(a) the brake thermal efficiency,
(b) the percentage of the energy supplied by the fuel which is carried away by
the cooling water, friction and radiation,
(c) the indicated mean effective pressure,
(d) the indicated specific fuel consumption
