Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
INVESTIGATIONS ON BIODIESEL FROM WASTE COOKING OIL AS DIESEL FUEL SUBSTITUTE Jagannath Hirkude1, 2*, Atul S. Padalkar1 and Jisa Randeer1 1
Padre Canceicao College of Engineering, 403722, Goa, India, 2
Sinhgad College of Engineering, 41, Pune, India.
ABSTRACT The waste cooking oil (WCO) as alternative fuel for diesel engines is the aim of this investigation. The high viscosity and poor volatility are the major limitations of waste cooking oil for their utilization in diesel engine. The most convenient method to use waste cooking oil as fuel is to convert it into biodiesel through transesterfication. The properties of waste cooking oil methyl ester such as viscosity, specific gravity, calorific value and flash point temperature were determined and compared with mineral diesel. This paper presents the results of investigations carried out on a brand new (Laxmi Industries, India made), single-cylinder, four-stroke, direct-injection, diesel engine operated with biodiesel of waste cooking oil blended with mineral diesel. Performance parameters like brake thermal efficiency, brake specific fuel consumption, exhaust gas temperature have been discussed. Present study is also carried out to investigate emission characteristics (particulate matter, SOx, NOx, CO2, and CO) of blended biodiesel with mineral diesel in different composition. The performance parameters for different WCO biodiesel blends were found to be very close to diesel and the emission characteristics of engine improved significantly. It is possible to save
21606 by running the engine
on B50 mode (Daily 6 hour’s operation for 300 days).The experimental results proved that use of biodiesel (produced from waste cooking oil) is viable option to diesel in diesel engine.
Keywords: Waste Cooking oil, Biodiesel, Diesel engine _______________________________________________________________________________________ * Author for Correspondence E-mail:
[email protected] Tel: +91-832-2791266, Fax: +91-832-2791268
INTRODUCTION
Used vegetable oil is increasingly attracting interest because of its potential to be used as diesel
The used vegetable oil is classified as waste, while
substitutes known as bio-diesel. Direct synthesis via
its potential as a liquid fuel through physical and
transesterification reaction of vegetable oils will
chemical conversion remains highly interesting.
yield bio-diesel.
©STM Journals 2010. All Rights Reserved
1
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
One of the advantages of these fuels is reduced
production and emission testing in the past two
exhaust gas emissions. Experience has shown that
decades. Most of the current challenges are targeted
vegetable oil based fuels can significantly reduce
to reduce its production cost, as the cost of biodiesel
exhaust gas emissions, including carbon monoxide
is still higher than its petro-diesel counterpart. This
(CO), carbon dioxide (CO2), and particulate matter
opens a golden opportunity for the use of waste
(PM) [1-2]. Because of their insignificant sulfur
cooking oil as its production feedstock. Everywhere
content, the sulfur dioxide (SO2) emissions are low
in the world, there is an enormous amount of waste
[3]. However, emissions of oxides of nitrogen (NOx)
lipids generated from restaurants, food processing
are in general, higher than those for mineral diesel
industries and fast food shops everyday. Reusing of
fuel. Nye et al. [4] have collected waste fried oil
these waste greases cannot only reduce the burden
composed of partially hydrogenated soybean oil and
of the government in disposing the waste, but also
margarine and converted to biodiesel. Murayama et
lower the production cost of biodiesel significantly
al. [5] have used methyl esterified WCO in both
[8-12].
direct and indirect diesel engines. The particulate emissions from direct injection engine were found to
There is need to convert waste cooking oil from
be higher than indirect injection engine. Reed et al.
kitchen waste into biodiesel and transesterification
[6] have tested biodiesel produced from WCO in a
is the most suitable process for this conversion.
Denver public bus. The engine output power using
Present
biodiesel was comparable to that of diesel. The
performance
smoke opacity was reduced using biodiesel. Yu et al.
blended waste fried oil biodiesel with mineral diesel
[7] have carried out performance and emission
in different compositions. The performance of
analysis using WCO and observed similar engine
diesel engine with mineral diesel has been
performance and higher levels of CO, NO2 and SO2
considered as the baseline.
study is and
carried emission
out
to
investigate
characteristics
of
compared with that of diesel. MATERIALS AND METHODS Currently, compared to petroleum-based diesel, the high cost of biodiesel is a major barrier to its
The raw material (i.e. waste cooking oil) was
commercialization. It is reported that approximately
collected from different hotels in Goa, a premier
70%–85% of the total biodiesel production cost
tourist destination in India. The used fried oil was
arises from the cost of raw material. Use of low-cost
filtered to remove food residues and solid
feedstock such as WCO should help biodiesel
precipitate by using double layer of cheesecloth in a
competitive
diesel.
funnel. In the transesterification it is important that
Numerous studies have been conducted on biodiesel
the oil contains very minimal amounts of water
in
price
with
petroleum
©STM Journals 2010. All Rights Reserved
2
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
because every molecule of water will destroy a
used against 1000 ml of waste fried palm oil. This
molecule of catalyst. In order to avoid soap
solution was stirred at 600 rpm for 15 minutes and
formation due to water the filtered fried oil was
glycerin was allowed to settle for 24 hours. The
dried at 60 oC for 10 minutes using a microwave
biodiesel layer was separated from the glycerol
oven. To the preheated mixture of waste fried oil
layer in a separating funnel. Transesterification
and methanol, NaOH was added. The amount of
process followed to produce biodiesel from WCO is
sodium hydroxide needed was 7.7 grams per liter by
shown in figure 1. The process of biodiesel
titration with waste fried oil. 200 ml of methanol is
formation is shown in Figure 2.
Fig. 1: Transesterification process
©STM Journals 2010. All Rights Reserved
3
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
Fig. 2: Process of biodiesel formation
©STM Journals 2010. All Rights Reserved
4
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
Fig. 3: Different blends of biodiesel and mineral diesel
The fuels prepared for testing purpose were B50
Viscosity of WCO, WCO biodiesel and mineral
(50% biodiesel + 50% mineral diesel), B70 (70%
diesel was determined using redwood viscometer.
biodiesel + 30% mineral diesel), B90 (90% biodiesel
The viscosity of WCO biodiesel found very close to
+ 10% mineral diesel), B100 (100% biodiesel) and
the diesel fuel, since transesterfication of WCO
mineral diesel. Figure 3 shows different blends of
provided a significant reduction in viscosity,
biodiesel and mineral diesel.
especially at low temperatures. The addition of WCO biodiesel slightly increased the viscosities of blends.
The performance of a direct injection (DI) diesel
Calorific value was estimated with help of bomb
engine is affected by the spray characteristics of the
calorimeter and found lower than that of mineral
fuel emerging through the injector holes. Some
diesel. The flash point temperature was found out
researchers have reported that the most detrimental
by flash point apparatus and it is more than 93oC
parameter in the use of vegetable oil as fuel is its
which is minimum requirement for biodiesel based
higher viscosity [13]. The high viscosity is the cause
on ASTM D 6751- 09. The properties of WCO,
of blockage of fuel lines and filters, high nozzle
WCO biodiesel and mineral Diesel fuel are presented
valve opening pressures and poor atomization [14].
in Table 1. The properties of WCO biodiesel are in
The problems of high fuel viscosity can be overcome
the acceptable ranges.
by using esters, blending and heating [15]. The properties of biodiesel produced are very important and should be taken into consideration before testing it in the engine [16-17].
©STM Journals 2010. All Rights Reserved
5
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
Table 1: Properties Comparison Properties
WCO
Biodiesel
Diesel
Viscosity at 400C (cst)
65.2
6.8
Specific gravity
0.915
0.870
Calorific Value (KJ/kg)
31000
39000
43000
Flash point 0C
180
140
70
4.320 0.830
The performance and exhaust emission tests were
fuel to flow into the engine. The torque was
carried out on constant speed, direct injection
measured
single cylinder diesel engine. The experimental set
dynamometer. The engine speed (rpm) was
consists
measuring
measured by electronic digital counter. The
equipment, and exhaust gas analyser with digital
performance parameters, break thermal efficiency
temperature indicator. The engine specifications
and brake specific fuel consumption were
are given in Table 2. The engine was coupled to an
calculated from measured data. The exhaust gas
electrical
temperature was measured by using an electronic
of
diesel
alternator
engine,
fuel
connected
with
electric
using
indicator
swinging
with
field
electrical
heaters of 0.5 kW each. Arrangement was made
digital
iron-constantan
for break loading in the range of 0.5 kW to 4 kW.
thermocouple. Emission analysis was carried for
The specific fuel consumption was calculated by
exhaust gas emissions particulate matter, CO2,
measuring the time taken for a fixed volume of
SO2, NO2, and CO.
Table 2: Engine Specification Make
Laxmi Industries. Kolhapur (India)
Rated Power
3. 8 kW
Rated Speed
1500 rpm
Number of cylinders
1
Bore X Stroke
80 X 110 mm
Combustion Chamber
Direct injection with bowl in piston
Standard injection timing
270 BTDC
Standard injection pressure
190 bar
©STM Journals 2010. All Rights Reserved
6
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
Fig. 4: Experimental Setup
The fuels were tested in the engine running at 190 bar
original
fuel
injection
pressure.
Table 4.
Engine
experiments were conducted at constant speed of 1500 rpm at different loads (from 0.5 kW to 4 kW). The engine was coupled with a single phase, 220 V AC alternator. The alternator is used for loading the engine through a resistive load bank. The load bank consists of eight heaters with 0.5 kW capacities each. The schematic layout of the experimental setup for the present investigation is shown in Fig. 4. Fig. 5: BSFC for diesel and different blends. RESULTS AND DISCUSSION Brake Thermal Efficiency (BTE) of WCO Brake Specific Fuel Consumption (BSFC) was
biodiesel in the blend compared to diesel in the
found to increase with higher proportion of WCO
entire load range (Fig 6). Brake thermal
biodiesel in the blend compared to diesel in the
efficiency of B50 at rated output observed very
entire load range (Fig.5). Calorific value of WCO
close to diesel. It is only 3% less than that of
biodiesel is lower compared to that of diesel,
mineral diesel. Oxygen present in the fuel
therefore increasing proportion of WCO biodiesel in
molecules
blend decreases the calorific value of the blend
characteristics but higher viscosity and poor
which results in increased BSFC of WCO biodiesel
volatility of WCO biodiesel lead to their poor
was lower than that with diesel. Estimations of the
atomization
standard errors in reported data is provided in
Therefore brake thermal efficiency was found to
©STM Journals 2010. All Rights Reserved
improves
and
the
combustion
combustion
characteristics.
7
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
be
lower
for
higher
blend
concentrations
CO2 emissions are reduced by 70% with B100
compared to that of mineral diesel. Brake thermal
compared with mineral diesel. The emissions of
at part load conditions are very close with diesel.
CO increase with increase in load. Higher the load, richer fuel-air mixture is burned, and thus more CO emissions for WCO biodiesel are reduced by 19% with B50 and this reduction increases further with increase in concentration of biodiesel in the mixture. This is because additional oxygen content
in
biodiesel
enhances
complete
combustion of the fuel and its higher cetane number. The higher the cetane number, the lower the probability of fuel-rich zones formation, Fig. 6: BTE for diesel and different blends.
usually related to carbon monoxide emissions. Particulate
matter
percentage
reduces
with
The exhaust gas temperature with blends having
increase in WCO biodiesel quantity in the blend.
higher percentage of WCO biodiesel observed
The least percentage of particulate matter
higher compared to that of mineral diesel as WCO
observed with pure WCO biodiesel (B100).
biodiesel contains constitutes of poor volatility,
Reduction in Sulphur dioxide emission is found
which burns during the late combustion phase
with increase in concentration of WCO biodiesel
(Fig 7).
because of their insignificant sulfur content, the sulfur dioxide (SO2) emissions are low. NOx emission was increased with increase in WCO biodiesel concentration in the blend. This is because of the fact that the injection process is slightly advanced with biodiesel. Average WCO biodiesel emissions compared with mineral diesel is shown in the Table 3.
Fig. 7: EGT for diesel and different blends
©STM Journals 2010. All Rights Reserved
8
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
Table 3: Average WCOME emissions compared with diesel Emission type
B100
B90
B70
B50
Carbon Dioxide
-70%
- 65%
-51%
-35%
Carbon Monoxide
- 44%
- 40%
-33%
-19%
Particulate Matter
- 45%
-38%
-33%
- 21%
NOX
+ 13%
+11%
+9%
+5%
SOX
-100%
-90%
-70%
-50%
Table 4: Estimation of standard errors in the reported data Parameter BSFC (kg/kWh) o
Exhaust Gas Temperature( C)
Diesel
B-50
B-70
B-90
0.013
0.011
0.014
0.012
0.015
2.5
2.60
2.65
3.75
2.75
0.242
0.254
0.26
0.252
Brake Thermal Efficiency (%) 0.235
B-100
For the conversion of waste fried oil, methanol and
operation for 300 days, it is possible to save
sodium hydroxide are available at a rate of Rs
21606 by running the engine on B50 mode.
60/litre and Rs 250/litre respectively. The cost of waste fried oil considered was almost zero because
CONCLUSIONS
it’s treated as discarded waste, harmful to the environment. Biodiesel cost will depend greatly on
The prospectuses of waste cooking oil based fuel
methanol prices and economy can be achieved by
production are very attractive for conservation of
varying the grade of methanol used. By-product of
energy for developing country like India. It has
trans-esterification is industrial grade glycerin which
been seen that the discarded waste cooking oil has
has industrial use and can be sold with or without
good potential as substitute for diesel fuel. Cost of
processing, as it is an important constituent in
conversion of biodiesel from waste cooking oil is
chemical, pharmaceutical and cosmetic industry.
very less (
The cost of production of 1 liter biodiesel including
market price of diesel ( 35 per liter) even though
cost of methanol, NaOH, collection, transportation,
it is heavily subsidized in India. In the present
labour and processing is 16.75. From performance
investigation a host of blends of biodiesel from
analysis it is observed that for daily 6 hours
waste cooking oil with mineral diesel oil were
©STM Journals 2010. All Rights Reserved
16.075 per liter) compared with
9
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
prepared and tested on a single cylinder constant speed diesel engine for its performance and
5. Yasufumi Y. et al. Society of Automotive Engineers 1999. 1913–20p.
emissions. The performance parameters for
6. Murayama T. et al. Proceedings of the
different WCO biodiesel blends found to be very
Institution of Mechanical Engineers, Part
close to diesel. Brake specific fuel consumption
D: Journal of Automobile Engineering
was found slightly higher for waste cooking oil
2000. 214. 141-48p.
biodiesel blends compared with mineral diesel. The brake thermal efficiency was found slightly
7. Reed T. B. et al Biomass and Bioenergy 1992. 3. 111–15p.
lowers (3% at rated output) for waste WCO
8. Yu C. W. et al. Proceedings of the
biodiesel blend compared with mineral diesel.
Institution of Mechanical Engineers, Part
From emission analysis it has been observed that
D: Journal of Automobile Engineering
WCO biodiesel can significantly reduce exhaust
2002. 216. 237–43p.
gas emissions, including carbon monoxide, carbon dioxide, sulpur dioxide and particulate matter.
9. Meng
X.
et
al.
Fuel
Processing
Technology 2008. 89 (9). 851-57p.
NOx emission was higher by 5% to 13% with
10. Mittelbach M. et al. Journal of the
increase in WCO biodiesel concentration. Authors
American Oil Chemists’ Society 78.
like to conclude from this investigation, that
573–77p.
biodiesel from WCO can be technically and economically feasible as alternate fuel for diesel.
11. Lee K. T. et al. Journal of the American Oil Chemists’ Society 2002. 79. 191–95p. 12. Mittelbach M. et al. Journal of the American Oil Chemists’ Society 1999. 76.
REFERENCES
545–50p. 1. Graboski M. S. et al. Progress in Energy and Combustion Science 1998. 24.
Agricultural Engineers 1982. 82-91p.
125-64p.
14. Nwafor O. M. I. et al. Journal of Applied
2. Gonzalez M. E. et al. Environmental
Energy 1996. 54(4). 345-54p.
Monitoring and Assessment 2000. 65.
15. Romano
13–20p.
S.
American
Society
of
Agricultural Engineers 1982, 106-16p.
3. Murayama T. INFORM. 1994. 5(10). 1138 – 45p.
16. Lang X. et al. Bioresource Technology 2001. 80. 53–62p.
4. Nye M. J. et al. Journal of the American Oil
13. Tahir A. R. et al. American Society of
Chemists’
Society
1598–602p. ©STM Journals 2010. All Rights Reserved
1983.
60.
17. Canakci M. et al. Transactions of the ASAE (American Society of Agricultural Engineers) 2001. 44(6). 1429–36p. 10
Journal of Alternate Energy Sources & Technologies Volume 1, Issue 1, December, 2010, Pages 1-10.
©STM Journals 2010. All Rights Reserved
11