2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
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The engine was coupling with an a.c. dynamometer
of which the electrical load could be adjusted. The
engine torque could be directly estimated from the
force measured by a digital load cell and the load cell
arm. The engine speed was measured with a digital
proximity sensor (accuracy 0.03 % F.S.) and the fuel
consumption was directly calculated from the
difference of oil level in an oil-feeding cylinder and the
operating time. The engine test bed is shown in Fig. 3.
The engine power and the specific fuel
consumption could be evaluated as follows:
The engine torque (N m) could be calculated from
rFT
(1)
F is force (N) which could be read directly from the
load cell and
r is the radius arm of the
load cell (m).
The engine power, P
(kW), could be calculated by
1000
60
2
u
NT
P
S
(2)
N is engine speed
(rpm).
The specific fuel consumption (g/kW hr)
could be
calculated by
P
m
sfc
f
'
(3)
m
f
’ is mass rate of fuel consumption
(g/hr).
The engine gas emission
could be read directly
from
a
flue gas analyzer TESTO 350 XL of which CO
(ppm) , NOx (ppm) were main items in this study. The
details of the emissions and the measuring range of the
instrument are shown in Table III.
TABLE
III
D
ETAILS OF EMISSIONS AND THEIR MEASURING RANGE OF
T
ESTO
350 XL.
Sensor
Measurement Range
O
2
0 to 25 vol. %
CO
0 to 10,000 ppm.
CO
2
0 to CO
2
max.
NO
0 to 3,000 ppm.
NO
2
0 to 500 ppm.
SO
2
0 to 5,000 ppm.
H
2
0 to 300 ppm.
C
x
H
y
0 to 4 Vol. %
Pressure
+/- 200 kPa.
Velocity
40 m/s.
Temperature
-40 to 1,200
o
C
Efficiency
0 to 120 %
%RH
0 to 100%
Black smoke
could be read directly with a Hermann
DO 285 Opacity Meter.
The tested engine speed was varied
from 1000 rpm
up to
2000 rpm with a step change of 200 rpm. At each
step, the engine was maintained steadily before data
measurement. Each experiment was performed 5 times
and the average value was undertaken.
IV. R
ESULTS AND DISCUSSIONS
Engine performances and Emissions
Figs. 4 and 5 show the engine torques and engine
powers when different types of fuels are used at
various engine speeds. For diesel oil, when 5 % of
water was mixed with (95/0/5), the engine torque and
the engine power were slightly lower than those
without water (100 % diesel oil) at low engine speed.
But when the engine speed was over 1400 rpm, the
performances were less than those of diesel oil
significantly due to the lower heating value with the
amount of water mixing. Similar results were found
with the emulsions of diesel/CPO/water. For
diesel/CPO/water at 90/5/5, the engine performances
were close to those of diesel/water at 95/0/5. The
engine torques and the engine performances dropped
with the percentages of CPO or water in the emulsions.
It could be noted that the engine could run steadily
when the percentages of CPO and water were not over
10 and 10 %, respectively.
Fig. 6 shows the specific fuel consumption of the
engine with the tested fuels which generally increases
with the engine speed. The engine with 100 % diesel
oil showed the best performance due to its highest
heating value. For diesel/CPO/water at 90/5/5, the
specific fuel consumption was close to the diesel mixed
with 5 % water at low engine speed but when the speed
was higher than 1400 rpm, more specific fuel
consumption was higher due to its lower heating
value. Again, when the percentages of CPO and water
were higher in the emulsion, higher specific fuel
consumptions were needed.
Fig. 4. Engine torque at different engine speeds
.
