Diesel Engine Emissions and Performance Characteristics under Cape Chestnut Biofuel 11
monitored were; SO2, NO and NO2. In order to detect
and measure the particulate matter (PM10) filters were
attached to the engine exhaust pipe. The readings from
the monitors were analyzed in real time of the engine.
2.5. Transesterification
The oil was transesterified using methanol as alcohol and
Potassium Hydroxide (KOH) as the catalyst. Every liter of
Cape Chestnut oil required 200 ml of methanol and the
amount of Potassium H y d ro xide was 1 % by weight of the
Methanol used. The catalyst was kept dry in an airtight
container during the storage since water promotes
saponification. The required amount of catalyst was
measured and dissol ved in t he alcohol befor e pouri ng int o
the corresponding volume of the Cape Chestnut oil. The
mixture was stirred and covered to avoid evaporation of
the alcohol into the atmosphere and left to settle for 24 hrs
after whic h there was a cle ar distin ction of b iodiese l at the
top and glycerin which settled at th e bottom. The alcohol
(methanol) reacted with the fatty acids in the Cape
Chestnut oil in the presence of the catalyst (Potassium
Hydroxide) to form mono alkyl (biodiesel) and glycerin.
2.6. Separation and Washing of the Biodiesel
After transesterification and overnight settling, results
showed methyl esters and glycerin distinctively sep arate.
Glycerin is denser and therefore settled at the bottom of
the containe r. The m ixture needed t o be se parated an d this
was done by sucking out the biodiesel from the top of the
container and leaving glycerin at the bottom to be dis-
posed of.
2.7. Biodiesel Drying
After gently washing three times with warm water, the
biodiesel was left overnight in the open for the evapora-
tion to take p lace and by the following day, all the water
had evaporated and biodiesel was ready for blending and
testing.
The process of biodiesel production from transesteri-
fication, separation, washing and drying took three days to
complete where upon blending was done by measuring
the necessary volumes of biodiesel. The volumes of bio-
diesel were 5, 20, 50 and 80 per cent while the balance of
the volume to make 100 per cent was diesel to make B5,
B20, B50 and B80 blends respectively.
2.8. Biodiesel Fuel Properties
2.8.1. Calorific Value
This was done with the help of a bomb calorimeter.
CTTWE in kj
HCV Mass ofFuel
(1)
where HCV = Higher Cal orific Value; TWE = Total wate r
equivalence in calories; CT=Corrected temperature.
A graph was drawn to determine the corrected tem-
perature rise and then the Equation (1) employed.
Total water equivalent = volume of water in calorimeter
+ water equivalent of bomb.
2.8.2. Specifi c Gra vi t y
The specific gravity of fuel is necessary to determine the
power input of the fuel and hence determine the thermal
efficiency and BSFC. Thermal efficiency, brake horse
power and BSFC were the parameters used to determine
the performance of the fuels in the study. The val ue of 908
Kg/m3 [1] for the density of Cape Chestnut Methyl Ester
was used.
The specific gravity of the blends was calculated using
Equation (2) [11 ].
blend
SG SGii
(2)
where SGblend is the specific gravity of blend and SGi
is
the specific gravity of component fuels and Xi is the
volume fraction of the mass i.
2.9. Fuel Consumption Measurement
The various fuels were used i n turns to run t he engine. The
time taken by test engine to consume 150 ml of each fuel
as indicated by the pipette was recorded. In order to start
the process th e p ipette was filled with fu el well abov e th e
top marking by opening the main supply valve. The en-
gine was operated on the main supply while isolating the
fuel from the pipet te. The m ain supply valve was t hen clo-
sed and the e ngine ope rated o n the fuel from the pi pette t o
determine the consumpti on. Subsequentl y , t he load was in-
creased by intervals of 0.225 Kg until the engine started to
run with difficulty at which point the load was considered
to be the maximum for that particular fuel at that speed.
2.10. Measurement of Exhaust Gases
The fuel consumption was recorded concurrently with
sampling of the emissions by the monitors attached to the
engine’s exhaust pipe. The emissions monitors were re-
cording the detected toxic gases NO, SO2 and NO2 at
intervals of every ten seconds in parts per million (ppm).
To evaluate the particulate matter emitted by fuels, a
filter was attached to the engine exhaust pipe which en-
abled it to pick any PM10 emitted as the exhaust gases
exited. Two filters were used, for the diesel and the other
for B100, B80, B50, B20 and B5. The reason why only
one filter was used for all the CCME and its blends is
because the PM10 in them was almost negligible for each
to be considered independently.
2.11. Evaluation of Exhaust Emission Gases and
Particulate Matter
The evaluati ons were d one for t he exhaust e missions f rom
Open Access JPEE
