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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

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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


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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


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Fig. 2: Process of biodiesel formation


4


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].


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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


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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


improves

and

the

combustion

combustion

characteristics.

7


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


8


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


16.075 per liter) compared with

9


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.

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