Internal Combustion Engine Laboratory
Testing of a Diesel Engine
The test engine is a single-cylinder. .4-stroke Diesel engine having a compression ratio of 16.7:1,
a bore of 114 mm. a stroke of 127 mm and a rated power of 3.4 kW at the rated speed of 600
rpm. The engine is equipped with a heavy flywheel of 609.6 mm diameter with a cooled brake
drum as a means of loading. The brake drum is water-cooled, and the rope ends on both sides of
the drum with spring balances. The test rig is also equipped with an air-box as a means to
measure air consumption and with a direct volumetric measurement of the fuel consumption. A
mechanical indicator is also installed, which produces a pressure-volume plot of the 4-stroke
Ambient pressure and temperature; engine speed; tension on both sides of the brake drum rope:
fuel consumption: vacuum inside the air-box; inlet and exit temperatures of engine cooling
water: inlet and exit temperature of brake drum cooling water; exhaust gas temperature.
1- Loosen the rope so that no load is applied to the engine, then start the engine and allow 5-10
minutes for warming-up.
2- Apply load to the engine by tensioning the rope and adjusting fuel flow such that the rated
speed of 600 rpm is obtained. Allow about 10 minutes for the engine to settle down. .Adjust
water flow such that water outlet temperature is about 75-90°C. Turn off the main fuel supply
and turn on the fuel, meter cock., then record the time for the fuel level to fall between marked
graduation on the meter. Record all other readings in the provided sheet.
3- Gradually increase the applied load by more tensioning the rope in increments of 200 N (40
lbs) and adjusting fluid flow such that the speed of 600 rpm is always maintained. Allow about
10 minutes between successive readings. Record all readings.
Take a total of at least 5 operating points.
1. For the point with the highest load make an energy balance sheet, i.e. how the fuel energy is
distributed among useful shaft work, energy in the exhaust, energy to the cooling water and
energy lost by convection and radiation.
2. Plot against (bd) on the x-axis the following quantities ηb : τ: (bmep): (bsfc).
Torque: τ = (F1-F2).r ; Power: (bd) = τ.ω= τ = (bmep). B 2 S
60 4 2 60
. F .VF (bp)
Input fuel power: Q F .q LHV ; Brake thermal efficiency: b .
Actual air flow rate: m A C d A 2P. A , where ΔP = ρw g Hmano sin α
. N mA
Ideal air flow rate: m A,ideal A B S 2
; Volumetric Efficiency: V .
4 2 60 m A,ideal
Rate of energy carried away by the cooling water: QCW m w C , w (Tw,o Tw,i )
. . .
Rate of energy carried away by the exhaust gases: QExh (m A m F )C , Exh (TExh T A )
In these calculations, the following constants may be assumed:
Cρ,w = 4.18 kJ/kgK; Cρ,Exh = 1.15 kJ/kgK; ρF = 840 kg/m3; Dorifice=25.4 mm.
Ambient Temperature, Ta = C
Ambient Pressure, Pa = mmHg
Test Speed F1 F2 VF tF ΔPorif mw Tw,i Tw,o TExh
No. (rpm) (N) (N) (CM3) (s) (mmH2O) (kg/s) (oC) (oC) (oC)