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October, 2017
AgricEngInt: CIGR Journal Open access at http://www.cigrjournal.org
Vol. 19, No. 3
Evaluation of the performance and emissions of a single cylinder diesel engine fueled by biodiesel and using exhaust gas recirculation Farzad Jaliliantabar1, Barat Ghobadian1*, Gholamhassan Najafi1, Rizalman Mamat2 (1. Department of Mechanics of Biosystem Engineering, Tarbiat Modares University, Tehran, Iran; 2. Faculty of Mechanical Engineering/Automotive Engineering Centre, University Malaysia Pahang, Pekan Pahang, Malaysia) Abstract: In this study, the effect of using biodiesel – derived from waste cooking oil – and exhaust gas recirculation (EGR) on engine performance and emissions of a single cylinder 4-stroke engine has been investigated.
Three engine speeds (1800,
2100 and 2400 rpm), three engine loads (25%, 50% and 75%), four biodiesel/diesel blend (B0, B5, B10 and B15) and four EGR rates (0%, 10%, 20% and 30%) have been applied to the engine.
The considered emissions of the engine, measured at exhaust,
were NOx, CO, CO2, HC and smoke.
The considered performance parameters were engine power, exhaust gas temperature
and brake specific fuel consumption.
The results of the study show that the addition of the biodiesel to the diesel fuel
increases NOx emission of the engine.
The highest decrease in NOX emissions while using the biodiesel and EGR was 63.76%
with B10 fuel blend and 30% EGR rate. engine due to biodiesel can be reduced.
Therefore, it can be stated that, using EGR, the increase of NOx emissions in the The simultaneous usage of EGR and biodiesel reduced CO emission of the engine of
4.04%, 12% and 1.73% for low, medium and high engine speed. so it compensated the increase of HC due to EGR. and biodiesel simultaneously.
The biodiesel decreased the HC emission of the engine and
The highest reduction in HC emission levels was 54.05% while using EGR
It is noticeable that the total amount of the smoke emission levels while using EGR and
biodiesel did not change considerably. Keywords: EGR, biodiesel, emission, ci engine Citation: Jaliliantabar, F., B. Ghobadian, G. Najafi, and R. Mamat. 2017. Evaluation of the performance and emissions of a single cylinder diesel engine fueled by biodiesel and using EGR. Agricultural Engineering International: CIGR Journal, 19(3): 80–91.
1
Introduction
source of energy and, in addition, in most cases it comes
from waste material; therefore, it represents a good way
One of the most interesting research area currently
to reuse waste materials (Ghobadian, 2012; Safieddin et
investigated in the field of internal combustion engines is
al., 2011). Biodiesel contains about 10% to 12% oxygen
to define and test new sources of primary energy. This is
content and therefore it can be also used as an oxygenate
due to exhaustion of fossil fuels reserves, associated to
additive.
health and environmental problems determined by them
The researches on using of biodiesel in internal
(Suh and Lee, 2016). Biodiesel is an alternative fuel
combustion engine have revealed that CO, CO2, smoke
widely accepted as a substitution for diesel fuel. The most
and HC raw emissions are generally decreased using the
significant aspect of the biodiesel is its similarity to diesel
biodiesel. On the other hand, NOx emissions levels
fuel. Biodiesel has characteristics so close to diesel fuels
usually increase, mainly due to the oxygen content of the
so that can be used in compression ignition engine
biodiesel (Suh and Lee, 2016; Ghazali et al., 2015).
without any engine modification. Biodiesel is a renewable Received date: 2016-09-06
Accepted date: 2017-02-07
In compression ignition engines, NOx emission levels are significant, due to sufficient availability of oxygen
Corresponding author: Barat Ghobadian, full professor,
and high temperature. On the other hand, compression
Department of Mechanics of Biosystem Engineering, Tarbiat Modares University, Tehran, Iran. Email:
[email protected].
ignition engines offer several advantages, most of all a significant fuel saving. Therefore, the research on
October, 2017
Evaluation of a diesel engine fueled by biodiesel and using exhaust gas recirculation
reduction of NOx using biodiesels has become one of the
Vol. 19, No. 3
81
trade-off will be found.
most popular researches in the engine field.
The factors varied during experimental campaign
Different technologies and methods have been
were engine load (25%, 50% and 75% full load), engine
introduced and tested to decrease the additional NOx
speed (1800, 2100 and 2400 rpm), percent of biodiesel in
deriving from biodiesel utilization. The principles of
biodiesel/diesel blend (B0, B5, B10 and B15) and EGR
these
rate (0%, 10%, 20% and 30%).
methods
are
to
lowering
the
combustion
temperature or remove some of the oxygen from the
2
Materials and methods
cylinder. Water addition for cooling the cylinder content during combustion has been applied either adding water
2.1
Specifications of the produced fuel
to the fuel as an emulsion or injecting water into the
Biodiesel is a methyl or ethyl ester made from
cylinder (Ithnin et al., 2015). Another widely used
vegetable oils or animal fats. It can be used as fuel in
method is to recirculate a portion of the exhaust gases
diesel engines or other thermal systems with no system
along the intake duct. This method, known as EGR, is
modifications because it presents characteristics similar to
effective in reducing the average temperature in the
fossil fuels. Biodiesel is typically produced through the
cylinder (Pedrozo et al., 2016).
reaction of a vegetable oil or animal fat with methanol in
Although EGR is a useful method to reduce NOx
the presence of a catalyst to yield glycerin and methyl
engine-out emissions, smoke emissions are increased
esters (Testing and Materials, 2009). The biodiesel fuel
(Rajesh and Saravanan, 2015). Combining EGR and
used in the current research was produced from waste
biodiesel utilization, it is commonly recognized that an
cooking oil in Renewable Energy Laboratory of Tarbiat
increase in CO, HC and smoke emissions due to EGR
Modares University, Tehran, Iran. The standard diesel
(Nabi et al., 2006) and in NOx due to biodiesel is obtained
fuel was the common fuel used for diesel engines in Iran.
(Sanjid et al., 2016). On the other hand, it is stated that
Some important characteristics of the produced biodiesel
the increase of NOx emission levels coming from
fuel along with the related standards, together with the
biodiesel utilization can be compensated using EGR (Pradeep and Sharma, 2007). Research activity is therefore addressed on the determination of the optimal
characteristics of traditional diesel fuel, are reported in Table 1. Table 1
Some important characteristics of the produced biodiesel fuel along with the related standards
EGR rate allowing a good trade-off between NOx and
Standard test Allowable Biodiesel method range
smoke emissions. It is commonly believed that 15%-20%
Specification
of EGR rate is a suitable range (Agarwal et al., 2011;
Kinematic viscosity
EN 14214
3.5-5
Maiboom et al., 2009; Mani et al., 2010; Pradeep and
Density
EN 14214
----
Sharma, 2007). However, the application of the EGR
2.2
Diesel
Unit
4.72
3.5
mm2/s
0.862
0.837
g/cm3
Specifications of tested engine and dynamometer
system on a small CI engine is not widely discussed in
Table 2 reports the main specifications of the engine
literature and there is not a comprehensive research on
tested during experimental campaign. In order to measure
the performance parameters and emissions of a CI
the engine torque, speed and output power, an
cylinder engine while using biodiesel.
eddy-current dynamometer (Schenk, Germany) was used.
Therefore, aim of this study is to discuss the
The dynamometer is able to measure power, rotational
utilization of an EGR system to decrease NOx emission
speed and torque up to 21 hp, 10000 rpm, and 80 Nm,
levels emitted by a single cylinder CI engine while using
respectively. The accuracy of the dynamometer was in
biodiesel in blend with traditional diesel fuel. In
the range of 0.5%-1%. An overall view of the engine test
particular: 1) the performance parameters and exhaust
setup is shown in Figure 1.
emission levels of a single cylinder engine while using
2.3
EGR system
EGR system and biodiesel fuel will be investigated; 2)
The EGR system used in this study was a cooled EGR
the appropriate EGR rate leading to best NOx-smoke
system. The EGR cooler and other parts of the system can
82
October, 2017
AgricEngInt: CIGR Journal Open access at http://www.cigrjournal.org
be seen in Figure 1. The EGR cooler was a tube-pipe
2.4
Vol. 19, No. 3
Fuel consumption measurement system
cooler (Figure 2). To measure the EGR rate of the engine,
The system consisted of a fuel tank, conjunctions, and
the following Equation (1) has been used (Lattimore et al.,
pipes for fuel transporting, sensor to measure the volume
2016).
of fuel, thermal transducers of the returned fuel, fuel EGR ratio
CO2(int ) CO2( amb )
100
CO2( exh ) CO2( amb )
(1)
pressure transducers, fuel pressure gauge and fuel temperature sensor. The measuring accuracy of the
where, CO2(exh), CO2(int) and CO2(amb) are the% CO2
system was ±1 cm3 h-1. The system had two digital
measured respectively at then engine exhaust, intake port
monitors for displaying fuel temperature in terms of °C
and in the ambient. The EGR rate has been regulated by a
and fuel consumption in terms of L h-1. The system is
valve.
equipped with fuel tank pressure controller to increase the Table 2
Specifications of the evaluated engine
accuracy of fuel consumption measurement. 2.5
Specifications of exhaust emissions analyzer
3LD 510
Model
Lombardini, Italy
Manufacturer
1
Number of cylinders
DITEST GAS 1000 exhaust emission analyzer was used.
90 mm
Stroke
This device measures CO and CO2% vol. as well as HC
85 mm
Bore
510 cm3
Displacement
12.2 hp (9 kW)
Rated output power (@3000 rpm)
determine O2% vol. and NOx ppm using chemical
33 Nm
Rated output torque (@1800 rpm)
sensors. Interfacing the device with AVL DISmoke 480
In order to measure the engine-out emissions, an AVL
ppm using infrared technology. The device could also
BT smoke opacimeter, it was also possible to characterize the smoke emission. The measurement accuracy and other characteristics of the analyzer are reported in the Table 3. Table 3
The accuracies of the measurements and the uncertainties in the measured results
Figure 1
Measured
Resolution
Accuracy
CO
0.01% vol.
