manuscript prakash

8/7/2019 Manuscript Prakash

http://slidepdf.com/reader/full/manuscript-prakash 1/19

International Conference on Renewable Energy, 2011

January 17-21, 2011

Jaipur, India

Prospects of pyrolysis oil from wood as alternative fuel

R.Prakash1, P. Gandhi

2, M.V. Saikumar

3, R.K.Singh

4, S.Murugan

5

1,2,3,5Department of Mechanical Engineering

4Department of Chemical Engineering

National Institute of Technology Rourkela Orissa, India-769 008

Abstract:

World is finding a major crisis or scarcity of conventional petroleum fuels. There is a lot of scope

for biomass based fuels to replace petroleum based fuels, as biomass based fuels are renewable in

nature are available in large quantity. There are different methods to derive fuels from biomass

like chemical conversion, pyrolysis etc., Pyrolysis is one of a technique to derive fuels from

biomass and waste solid substances. This paper describes the prospects of wood pyrolysis oil as an

alternative fuel for Compression Ignition engines. An attempt was made to use modified bio-oil

blended with diesel fuel in a single cylinder, four stroke, air cooled, and DI diesel engine. The

performance and exhaust emissions such as unburned hydrocarbons [UBHC], carbon monoxide

[CO], carbon-di-oxide [CO2] and nitric oxide [NO] were measured from the diesel engine at

different power outputs. The performance and exhaust emissions were studied from the engine

with three different WPO based fuels such as WPO diesel emulsion, and two WPO diesel

emulsions with addition of 2% and 4% Diethylether. The results were compared with the diesel

fuel data, analysed and it is presented in this paper. It is observed from the results that 1.94%,

3.02% and 2.94% increase in the brake thermal efficiency was achieved with WPO10, WPO10

with 2%DEE and WPO10 with 4%DEE. The NO and HC emissions were lower with only WPO

diesel emulsion. For the other emulsions the HC and NO emissions were higher than diesel fuel

operation.

.

Keywords: Pyrolysis, diesel engine, ignition improvers, performance, emission

*Author for correspondence ( [email protected])




January 17-21, 2011

Jaipur, India

2

1. Introduction

Many alternative fuels for diesel engines were introduced in the last two decades for replacement

of diesel fuel. Utilization of Biomass as an alternative fuel for compression ignition engine has a

great scope especially in agriculture based countries and developing countries. The bio mass can

be converted into a source of energy for such engines by adopting different techniques such as dry

combustion, anaerobic digestion, bio photolysis, pyrolysis, liquefaction, gasification, hydrolysis

and solvent extraction (Roy G. D). Out of this pyrolysis have advantages such as simple and low

pressure operation, negligible waste product and high conversion efficiency of the order of 83%. It

is the thermal decomposition process of waste substances in the absence of oxygen. Pyrolysis of

biomass may yield solid, liquid and gaseous products (David Chiaramonti).

Biomass resources that can be used for energy production includes a wide range of materials such

as forest residues, energy crops, organic wastes, agricultural residues etc. Agricultural waste, a

readily available biomass, is produced annually worldwide and is under utilization almost

(Bridgwater A.V and Toft A.J).

Biomass resources can be divided into three categories (Bridgwater A.V). They are;

i) Wastes: Agricultural production wastes, agricultural processing wastes, crop residues,

mill/timber wood wastes, urban wood-wastes and urban organic wastes.

ii) Forest products: Wood, logging residues, trees, shrubs, wood residues, sawdust, bark etc.,

from forest clearings.

iii) Energy crops: Short rotation of woody crops, herbaceous woody crops, grasses, starch crops

(corn, wheat and barley) sugar crops(cane and baggase), oilseed crops (sunflower, soyabean,

safflower).

1.1 Biomass conversion processes

Biomass can be converted into useful products by two main processes.

1.1.1 Thermo-chemical processes

Different methods are used in thermo chemical processes for converting biomass into useful

energy which are a) Combustion b) Gasification c) Liquefaction d) Hydrogenation e) Pyrolysis.

Out of all pyrolysis is advantageous than remaining processes because it can convert biomass

directly into solid, liquid and gaseous products by thermal decomposition of biomass in the




January 17-21, 2011

Jaipur, India

3

absence of oxygen (Ralph P. Overend). Pyrolysis process can be classified as slow pyrolysis or

low temperature conversion and flash pyrolysis or fast pyrolysis.

The pyrolysis oil has high oxygen content which burns smoothly and cleanly and has the potential

for alternative source of fuel. But pyrolysis oil also contains many reactive components that can

form higher molecular weight species. So these reactions result in increase in viscosity and

decrease in volatility, which is unfavorable for fueling in diesel engines. Hence it is necessary to

modify the fuel so that it can be used as an alternative fuel. The hydroscopic nature of the

pyrolysis oil weakens the stability of pyrolysis oil when it is blended with diesel fuel (Stefen

Czernik).

1.1.2 Bio-chemical processes

Anaerobic digestion and alcoholic fermentation are widely used in bio-chemical processes for

obtaining energy from biomass. High moisture content such as animal manure and bio-sludge can

be the products of these processes. These processes are due to biological actions that convert semi-

solid or liquid biomass into a biogas or liquid fuel (ethanol) (Ralph P. Overend).

2. Pyrolysis Process for Production of Bio-Oil (Zhang Qi)

2.1 Pyrolysis

Pyrolysis is the conversion of one substance into another by means of heat with or without the aid

of a catalyst. It involves heating in the absence of air or oxygen. Pyro gas, pyrolytic oil and char

are the products of pyrolysis process. Pyrolysis process can be classified as slow pyrolysis and fast

pyrolysis. The pyrolytic breakdown of wood produces a large number of chemical substances.

Some of these chemicals can be used as substitutes for conventional fuels (Dinesh Mohan).

2.2 Bio-oil

The liquid product from biomass pyrolysis is known as pyrolysis oil or bio-oil or bio crude oil.

Bio-oil is not a product of thermodynamic equilibrium during pyrolysis but it is produced with

short reactor times and rapid cooling or quenching from pyrolysis temperature.

2.3 Factors affecting pyrolysis reaction

1. Type of biomass feed stock

2. Particle size




January 17-21, 2011

Jaipur, India

4

3. Feedstock moisture

4. Process parameters like vapour phase residence time, heating rate & temperature

5.

Reactor and recovery unit design.

2.4 Properties of bio-oil

Bio oils are mixtures of multi-component of different size molecules derived from

depolymerization and fragmentation of cellulose, hemicelluloses and lignin. The various properties

of bio-oil are described as follows:

2.4.1 Water content

Bio-oil has high water content in the order of 15-30% since it is derived from the original moisture

in the feedstock and product of dehydration during the pyrolysis reaction and storage. The

presence of water in bio-oil lowers the heating value and flame temperature. But on the other hand

presence of water reduces the viscosity and enhances the fluidity, which is good for atomization

and combustion of bio-oil in engine.

2.4.2 Oxygen content

Bio-oil has 35-40% oxygen content distributed in more than 300 compounds depending on the

biomass resource and pyrolytic process temperature, residence time and heating rate. The high

oxygen content leads to the lower energy density than the conventional fuel by 50% and

immiscibility with hydrocarbon fuels also.

2.4.3 Viscosity

The viscosity of bio-oils vary depends on the biomass feedstocks and pyrolysis process. Reduced

viscosity is found with bio-oils with higher water content and less water insoluble compounds.

2.4.4 Acidity

Bio-oils contain carboxylic acids such as acetic acids and formic acids which leads to low pH

values of 2-3. Acidity makes bio-oil very corrosive and extremely severe at high temperature

which requires suitable materials when using bio-oil in transport application.

2.4.5 Heating value

Bio-oils have lower heating value than vegetable oils due to more water content present in the bio-

oil. Fuel consumption will be more to produce the same power output.




January 17-21, 2011

Jaipur, India

5

2.4.6 Ash content

Ash content in the bio-oil varies between 0-0.2%. The presence of ash in bio-oil can cause erosion,

corrosion and kicking problems in the engines and the valves and even deterioration takes place

when ash content is more than 0.1wt%. Alkali metals specifically Sodium, Pottasium, and

Vanadium are problematic components of the ash. They are responsible for high temperature

corrosion and deposition and calcium is responsible for hard deposits. Hot gas filtering will reduce

the alkali metals present in the bio-oil.

3. Upgrading of Bio-Oil (Zhang Qi)

3.1 Hydrodeoxygenation

The hydro-process is performed by hydrogen providing solvents activated by the catalysts of Co-

Mo, Ni-Mo and their oxides loaded on Al2O3 under pressurized conditions of H2 and/or Co.

Oxygen is removed as H2O and CO2, and then the energy density is elevated.

3.2 Catalytic Cracking of Pyrolysis Vapours

Oxygen containing bio-oils are catalytically decomposed to hydrocarbons with the removal of

oxygen as H2O, CO2 or CO. ZnO a mild catalyst on the composition and stability of bio-oils in the

conversion of pyrolysis vapours and liquid yields were not reduced.

3.3 Emulsification

This is the simplest way to use bio-oil as transport fuel by combine it with diesel directly.

Although the bio-oils are immiscible with hydrocarbons, they can be emulsified by the aid of a

surfactant. Emulsification does not demand redundant chemical transformation, but the high cost

and energy consumption input cannot be neglected.

3.4 Steam Reforming

Production of hydrogen from steam reforming of bio oil is possible way of upgrading bio-oil.

3.5 Chemicals Extraction

Chemicals like phenols, volatile organic acids, levoglucosm etc can be extracted from bio-oil.

4. Design and Fabrication of Pyrolysis Setup

In this study pyrolysis oil was obtained through vacuum pyrolysis process in a fixed bed reactor.

Thick wood obtained from packing container box taken as sample, cut into small chips, washed,




January 17-21, 2011

Jaipur, India

6

dried. The schematic diagram of the pyrolysis process for deriving wood pyrolysis oil was given in

Figure 1.The chips were fed into an externally heated mild steel reactor unit. The fed chips were

heated up in the reactor unit in the absence of oxygen. The reactor used for production of wood

pyrolysis oil is cylindrical in shape with inner diameter 200mm and outer diameter 250mm and a

height of 250mm. The reactor is fully insulated by glass wool with thickness 50mm and refractory

lining. The heat input to the electrical heater was 3kW. The temperature of the reactor was

measured with the help of a temperature indicator provided in a temperature controller unit. The

temperature of the reactor was controlled by a PID controller. The pyrolysis process for deriving

wood pyrolysis oil was carried out at 5000C. The products of pyrolysis in the form of vapour were

sent to a water cooled condenser and the condensed liquid was collected in a container.The

properties of wood pyrolysis oil is compared with diesel fuel and given in Table 1.

Table 1- Comparison of Fuel Properties (Zhang Qi and Yrjo Solantausta)

Fig.1 - Schematic diagram of pyrolysis setup

Properties ASTM Standard Diesel Fuel WPO

Specific gravity at 15 °C ASTM D 4052 0.83 1.2

Net calorific value[MJ/kg] ASTM D 4809 43.8 18

Flash point[°C] ASTM D 93 50 66

Pour point[°C] ASTM D 97 30 -27

Kinematic viscosityat 40 °C[cst]

ASTM D 445 2.58 13

Moisture content (wt %) - 0.025 15-30

Ash (wt%) - 0.13 0.01




January 17-21, 2011

Jaipur, India

7

5. Analysis of Wood Pyrolysis Oil

5.1 GC-MS Analysis

GC-MS chromatogram was considered to be a good approximation technique because it indicatesthe amount of various chemical compounds in the bio-oil. The mass spectra obtained from GC-MS

– QP2010 (SHIMADZU) instrument were interpreted through an automatic library search. The

chromatogram obtained from wood pyrolysis oil sample is shown in Figure 2.

Fig.2 - Gas chromatogram of wood pyrolysis oil sample

The GC-MS report of the pyrolysis oil is noted in the following Table 2.

The GC–MS of pyrolysis oil shows that the pyrolysis oil contents like Oleic acid, 1,3-Dimethoxy-

2-hydroxybenzene,Methoxyphenol are large in proportion. Most of the components identified are

the phenols with ketones and aldehydes groups attached, and nearly all the functional groups

showed the extensive existence of the oxygen. On the other hand, the analysis proved that the

abundant aldehydes and ketones make the pyrolysis oil hydrophilic and hydrated in nature that

makes unseperation of water from pyrolysis oil (Zhang Qi ).




January 17-21, 2011

Jaipur, India

8

Table 2 - Main components obtained from GC-MS analysis

Area % Compound Name

1.20 Tetrahydro-2-furanmethanol

4.86 3-Methlcyclopentane-1,2-dione

7.24 0-Methoxyphenol1.48 Ethylcyclopentenolone

3.17 1-hydroxy-2-methoxy-4-methylbenzene

4.63 1-hydroxy-2-methoxy-4-ethylbenzene

15.29 1,3-Dimethoxy-2-hydroxybenzene

3.98 1,2,4-Trimethoxybenzene

4.58 (E)-Isoeugenol

7.34 1,2,3-Trimethoxy-5-methylbenzene

1.50 2-Propanone, 1-(4-Hydroxy-3-Methoxyphenyl)

1.90 2,6-Dimethoxy-4-(2-Propenyl)Phenol

1.52 2,4-Hexadienedioc acid, 3-Methyl-4-Propyl, Dimethyl ester, (Z,E)

0.88 N-[2-(2-Isopropyl-phenoxy)-ethyl]-2-methylsulfanyl-benzamide

1.50 1,3-Diphenylpropane

4.48 2,6-Dimethoxy-4-(2-Propenyl)Phenol4.59 N-Methylene-1,2-diphenylethanamine

2.78 1-(2,6-Dihydroxy-4-methoxyphenyl)-1-butanone

6.65 n-Hexadecanoic acid16.70 Oleic Acid

1.95 2-(Acetyloxy)-1-[(Benzyloxy)Methyl]Ethyl acetate

1.76 Glycine, N-butoxycarbonyl-, propyl ester

5.2 FT-IR Analysis

Fourier Transform Infrared Spectroscopy is a measurement technique where spectra are collected

based on measurements of the coherence of a radiative source, using time-domain or space-domain

measurements of the infrared radiation (wikipedia). FT-IR test was carried out with Perkin Elmer

Spectrum ONE equipment which has a scan range of 450-4000 cm-1 with a resolution of 1.0 cm-1.

Fourier Transform Infrared absorption is related to covalent bonds and it provides detailed

information about the structure of molecular compounds. The results of FT-IR analysis are in the

form of graph plotted between wave number and percentage transmittance which will give the

information about the position of various bond vibrations distinguished by several modes such as

stretching, distortion, bending etc. The following bonds are found with the pyrolysis oil collected

from saw dust and listed in the Table 3.

Table 3 - Various bonds present in the WPO

Bond Wave number Wave length

N-H Stretch 3428 2.7 – 3.3C≡C, C≡N Stretch 2125 4.2-4.8C=O, Stretch 1714 5.4-6.1

C=C, Stretch 1514 5.9-6.3C-H, Bend in plane 1372 6.8-7.7

O-H, Bending 1273 6.9-8.3Sulphates 1107 8.9-9.3

C-Cl 752 13-14

The Figure 3 shows the FT-IR graph arrived with wood pyrolysis oil sample.




January 17-21, 2011

Jaipur, India

9

Fig.3 - FT-IR graph of wood pyrolysis oil sample

From the FT-IR graph it is observed that the wood derived pyrolysis oil has a few strong bonds of

carbon that may result to high carbon deposit on the piston, combustion chamber etc, when it is

used in the compression ignition engine.

6. Utilization of Wood Pyrolysis Oil in Diesel Engine

Pyrolysis oil derived from biomass has become attractive but it is still under development. Flash

pyrolysis oil was used as fuel in a small diesel power plant (Yrjo Solantausta). The pyrolysis oil

obtained from hard wood was tested for its physio-chemical properties. The pyrolysis oil was used

in Petter AVB test engine that had a capacity of 4.8kW at 2000 rpm. Different fuels such as diesel,

ethanol and pyrolysis oil were used as fuel with certain proportion of ignition improver added by

volume to pyrolysis oil and ethanol. For ethanol, 3% and 5% of ignition improver was addedwhereas for pyrolysis oil 3%, 5% and 9% of ignition improver was added. From the engine tests it

was observed that the injector nozzle coked very fast and the bore for the cylinder pressure

transducer was clogged. By fueling ignition improved ethanol as an intermediate fuel the problem

of miscibility of pyrolysis oil with diesel fuel was rectified. The best emission results except for

the smoke number were obtained with 5% ignition improver addition.

An experimental study was conducted to determine the feasibility of using flash pyrolysis oil of

wood in diesel power plants (Frigo. S). The study includes the spray analysis, engine tests, thermo

gravimetric analysis (TGA), single-drop reactor tests and corrosion tests. It was reported that the




January 17-21, 2011

Jaipur, India

10

flash pyrolysis oil needs to be modified or to be mixed with another substance to make the self

ignition possible. The engine was found to have difficulties such as build up of carbonaceous

injection system fault and engine seizing. Char generation was noticed in a TGA apparatus and in

the single droplet atmospheric reactor. Fast erosion of steel components in the diesel engines was

also noticed when it was fueled with wood pyrolysis oil. The high oxygen content reduces the

heating value drastically and also the stoichiometric air/fuel ratio. This requires more fuel

consumption than diesel fuel to obtain the same power .

Experiments were performed on a single cylinder engine with blends of wood pyrolysis oil with

different percentage of oxygenated compounds and micro emulsions of WPO in diesel fuel

(Bertoli. C). Two different fuels like Diethylene glycol dimethyl ether (Diglyme) WPO blends at

different percentages and two different emulsions with 30% of WPO in No.2 diesel fuel. Diglyme

is added with the pyrolysis to improve the self ignition characteristics. Lower NO emissions were

found with increasing the percentage of WPO. Hydro carbon emissions were also found to be

lower than diesel upto 30% WPO and beyond that it increased. Carbon monoxide emissions were

found to be more due to the poor self ignition characteristics of the WPO. It was noticed that

residuals were occasionally found to stick on nozzle stem and sac volume with no trace of

corrosion in the injection system. Pyrolysis oil contains many reactive components that can form

higher molecular weight species. Also the higher viscosity and poor volatility of wood pyrolysis

oil is unfavourable for fueling it in diesel engines. The hydroscopic nature of the pyrolysis oil also

weakens the stability of pyrolysis oil when it is blended with diesel fuel (Stefen Czernik ). Hence,

it is necessary to modify the wood pyrolysis oil so that it can be used as an alternative fuel in

diesel engines.

Emulsion is one of the techniques used while a fuel has to be mixed with another fuel of

hydroscopic nature. An emulsifier is required to mix a certain proportion of alcohol with pyrolysis

oil and a little ignition improver (Michio Ikura). The emulsifier generally extends the water

tolerance of alcohol/pyrolysis oil fuel blends. An emulsion was prepared for pyrolysis oil with

diesel fuel using a surfactant ranging from 0.8 to 1.5% by volume. The stable emulsion was

prepared using two surfactants namely hypermer and CANMET. The price of the earlier one was

higher for 30% emulsion than the later one. Further the fuel properties such as heating value

cetane number, viscosity and corrosivity were determined. The heating value and cetane number

of pyrolysis oil were too low compared to that of diesel fuel. It was observed that the viscosity was

found to reduce when the emulsion was prepared with a maximum of 20% pyrolysis oil.

Increasing the emulsifier content results in higher viscosity, but it offers stability to the emulsion.




January 17-21, 2011

Jaipur, India

11

Emulsifier upto 4% by volume can be used with additives like n-octanol, to reduce the viscosity of

the emulsion. It was also mentioned that the feed stock and pyrolysis process must be precisely

defined in order to allow the exact identification of the most appropriate emulsification technique.

Alahmer et al have studied the performance of a variable speed diesel engine operating with diesel

water emulsion. It was observed that a surfactant can be used to stabilize water in diesel mixture

which cannot be maintained by natural mixing of diesel with water because of their different

densities and forces of surface tension. Surfactants reduce the surface tension forces so that they

permit two different densities of liquid to form a stable emulsion. Polysorbate 20 [C58H114O26]

commercially known as Tween-20 is used as a surfactant whose stability and non toxicity make to

use it as detergent and emulsifier in a number of domestic, scientific and pharmalogical

applications. It is a poly oxyethylene derivative of sorbitan monalurate, and is distinguished by the

length of the poly oxythene from the other members of the tween range. Emulsion prepared with

an addition of Tween 20 surfactant 2% by volume with six different percentages of water as fuels

were tested in a diesel engine. It was observed from the results that the 5% by volume of water

diesel emulsion gave an optimum brake power and a brake thermal efficiency compared with the

other water diesel emulsions

Generally pyrolysis oil can be used as an alternative fuel in compression ignition engines by

adopting techniques such as blending, preheating, increasing injection pressure and improving

ignition quality (Michio Ikura). But, in case of wood pyrolysis oil the pilot injection, addition of

ignition improver and emulsification has been reported (Yrjo Solantausta, Bertoli. C, Michio

Ikura). Blending of WPO with diesel fuel exhibited a draw back as wood pyrolysis oil does not

miscible in diesel fuel and form stability. Therefore different emulsions of wood pyrolysis oil with

diesel using various surfactants have been carried out (Chiramonti. D). Many surfactants such as

Ampholak, Armotan, Carbopol, Hypermer, Tween 20, Span 20 have been reported to form stable

emulsions (Michio Ikura, Alahmer. A, Chiramonti. D). In the present investigation Polysorbate

20 [Tween 20] was used to emulsify the wood pyrolysis oil with diesel fuel. The properties of the

surfactant polysorbate 20 are given in the Table 4. Three percentages by volume of surfactant was

used to emulsify 10% of WPO with 90% of diesel fuel.




January 17-21, 2011

Jaipur, India

12

Table 4 - Properties of Polysorbate 20 (wikipedia)

In the present study, the surfactant Tween 20 was used to prepare an emulsion of WPO and diesel.

The emulsion of WPO and diesel was used as fuel in a single cylinder, air cooled, direct injection

diesel engine with addition of different percentages of ignition improver. The performance and

emission parameters of the engine was analysed, compared with diesel operation and presented in

this report.

7. Experimental Setup

Figure 4 shows the schematic diagram of the experimental setup. The engine [1] was coupled to an

alternator [2] to provide the loading. A control panel [3] located near the engine helps to operate

the alternator to provide the load to the engine by a load switch [4]. The exhaust gas temperature

was measured with the help of a temperature thermocouple [5] fitted on the exhaust pipe. Fuel was

admitted from fuel tank [6] to the engine through a fuel filter [9] and fuel pump [10]. The fuel

consumption was measured with the help of a burette [7] and a fuel sensor [8]. Air enters to an air

filter [11] and then to air box [12]. Air intake was measured by air flow sensor [13] that was fitted

in the air box. A speed sensor [14] was connected near the flywheel of engine to measure the

speed. The exhaust pipe [15] had a provision to access the probes of an AVL 444 exhaust gas

analsyer[16] that measured unburnt hydrocarbon [HC], carbon monoxide [CO] and nitric oxide

[NO] emissions. HC and NO emissions were measured in ppm and CO and CO2 were measured in

percentage. An AVL 437 C diesel smoke meter [17] was used to measure the smoke density of the

engine exhaust. Data collected like fuel consumption, speed, air flow and exhaust gas temperature

for the corresponding loads were fed to the data acquisition system [18] and displayed in the

monitor of the computer [19]. The specifications of the engine used are given in Table 5.

Properties Polysorbate 20

Molecular formula C58H114O26 Molar mass (g/mol) 1227.54

Density (g/mL) 1.1 Boiling point (oC) >100

HLB Number 16.7




January 17-21, 2011

Jaipur, India

13

Fig.4 - Schematic diagram of the Experimental Setup

Table 5 - Engine Specifications

Make/Model Kirloskar TAF 1

Brake power, kW 4.4

Rated speed, rpm 1500

Bore [mm] 80

Stroke [mm] 110

Compression Ratio 17.5:1

Nozzle Opening Pressure [bar] 200

Injection Timing [oCA] 23

The performance and exhaust emissions were studied from the engine running with three different

WPO based fuels which are WPO diesel emulsion, and two WPO based fuels which are WPO

diesel emulsions addition of 2% and 4% DEE. Diethyl ether [DEE] an ignition improver was

added at 2% and 4% by volume basis with the emulsion of WPO and diesel. All tests were carried

out by starting the engine with diesel fuel only. After running the engine with different emulsions

again the engine was run with diesel fuel to flush out the emulsion present in the fuel line.

1. Engine 5. Thermocouple 9. Fuel filter 13. Air flow sensor 17. Smoke meter

2. Alternator 6. Fuel tank 10. Fuel p 14. Speed sensor 18. Data acquisition system3. Control panel 7. Burette 11. Air filter 15. Exhaust pipe 19. Computer

4. Load switch 8. Fuel sensor 12. Air box 16. Gas analyser




January 17-21, 2011

Jaipur, India

14

8. Results and Discussion

8.1 Performance Parameters

Performance parameters of the diesel engine such as brake thermal efficiency, brake specificenergy consumption and exhaust gas temperature were determined for the tested fuels, compared

with diesel fuel operation, analysed and presented in this section.

8.1.1 Brake Thermal Efficiency

Figure 5 shows the variation of the brake thermal efficiency with brake power for different WPO

and diesel emulsions. It is observed from the figure that the brake thermal efficiency of diesel

fueled operation at full load is 28.64%.

0

5

10

15

20

25

30

35

0 1 2 3 4 5

B r a k e t h e r m a l e f f i c i e n c y ( % )

Brake Power (kW)

Diesel

WPO Emulsion

WPO Emulsion + 2% DEE


10

12

14

16

18

20

22

24

0 1 2 3 4 5

S p e c i f i c E n e r g y C o n s u m p t i o n ( M J / k W h r )

Brake Power(kW)

Diesel

WPO Emulsion



Fig.5 - Variation of Brake Thermal Efficiency with Brake Power Fig. 6 - Variation of Basic Specific Energy Consumption with Brake Power

In case of WPO-diesel emulsions the brake thermal efficiencies of three blends WPO10, WPO10

with 2% DEE and WPO10% with 4%DEE at full load are 30.58%, 31.66% and 31.58%

respectively. The brake thermal efficiency is higher for the emulsions compared to that of diesel.

The reason for higher thermal efficiency in case of WPO 10 may be due to lower viscosity of the

WPO diesel emulsion that leads to better fuel atomization (Murugan. S). It is evident from the

graph the increase in the addition of DEE increases the brake thermal efficiency of the remaining

emulsions as it is an ignition improver.




January 17-21, 2011

Jaipur, India

15

8.1.2 Brake Specific Energy Consumption

When two different fuels are blended together the brake specific fuel consumption will not be

more reliable because the calorific value and density of two fuels are different. In such a case

brake specific energy consumption will be more appropriate. The variations of the brake specific

energy consumption for the tested fuels are shown in Figure 6. The BSEC of a blended fuel is the

product of the BSFC and calorific value of the corresponding blend. The BSEC of diesel fuel

varies from 21.61MJ/kWh at low load to 12.57 MJ/kW h at full load. It can also be observed from

the figure that the BSEC values for WPO diesel emulsions are 11.72MJ/kWh, 11.36MJ/kWh

and11.39MJ/kWh respectively. The energy consumption is higher in the case of emulsions

because of this lower energy content. Therefore the energy required to produce the same power

output at the corresponding load is more than that of diesel operation.

8.1.3 Effect on Exhaust Gas Temperature

Exhaust gas temperature measured from the engine is an indication for the conversion of heat into

work. It is observed from the Figure 7 that exhaust gas temperature varies from 118 0C to 2690C at

full load for diesel operation. It is evident from the figure that the exhaust gas temperatures of the

different WPO diesel emulsions are higher than diesel fuel operation. This is due to heat release in

the later part of the combustion process (Shailendra Sinha P).

0

50

100

150

200

250

300

350

400

0 1 2 3 4 5

E x h a u s t G a s T e m p e r a t u r e ( d e g C )

Brake Power (kW)

Diesel

WPO Emulsion



Fig.7 - Variation of Exhaust Gas Temperature with Brake Power




January 17-21, 2011

Jaipur, India

16

8.2 Exhaust emissions

8.2.1 NO emissions

Figure 8 shows the formation of NO at various brake power for the different emulsions and dieselfuel. Nitric oxide constitutes more than 90% of the oxides of nitrogen in an engine exhaust (Paul

Degobert). The formation of oxides of nitrogen is due to thermal root leading to thermal NO,

hydrocarbon fragment related root leading to prompt NO and fuel bound nitrogen that results fuel

bound NO. Two principles factors that affect formation of NO are temperature and oxygen

fraction (Mukunda .H.S).

0

50

100

150

200

250

300

350

400

0.0 1.0 2.0 3.0 4.0 5.0

Brake power(Kw)

N O

e m

i s s i o n s

m

Diesel

WPO10

WPO10+DEE2%

WPO10+DEE4%

0

0.005

0.01

0.015

0.02

0.025

0.0 1.0 2.0 3.0 4.0 5.0

Brake Power (kW)

C O e

m i s s i o n s ( %

)

Diesel

WPO Emulsion



Fig.8 - Variation of NO emissions with Brake Power Fig. 9 - Variation of CO emissions with Brake Power

It is observed that the NO emissions are lower for WPO diesel emulsion due to more water content

in the wood pyrolysis oil which reduces the combustion temperature. Addition of DEE improved

the combustion that results in higher NO emissions.

8.2.2 CO emissions

CO emissions from WPO-diesel emulsions are compared with diesel fuel and shown in the Figure

9.The CO emission is an indication for incomplete combustion of fuel air mixture that takes part in

the combustion. Carbon monoxide emission from engine exhaust is lower in the compression

ignition engines compared to spark ignition engines since the compression ignition are always

operated with lean mixture (Ganesan.V). The CO emissions of WPO-diesel emulsions are slightly

higher than diesel fuel due to poor atomization of the emulsion.




January 17-21, 2011

Jaipur, India

17

8.2.3 Carbon-di-oxide

Carbon-di-oxide is the major product of complete combustion. Generally more the oxygen

available for combustion then more the Carbon-di-oxide will be formed (Pundir .B.P). It is

observed from the Figure 10 that in the WPO diesel emulsion, wood pyrolysis oil has more water

content in it, so it produces less carbon-di-oxide gases due to incomplete combustion. On addition

of DEE with the WPO diesel emulsion more CO2 were found in the exhaust which indicates the

improved combustion.

0

0.5

1

1.5

2

2.5

0.0 1.0 2.0 3.0 4.0 5.0

Brake Power (kW)

C

a r b

o

n

- d

i - o

x i d

e

%

Diesel

WPO Emulsion

WPO Emulsion + 2% DE E

WPO Emulsion + 4% DE E

0

2

4

6

8

10

12

14

16

0.0 1.0 2.0 3.0 4.0 5.0

Brake Power(kW)

U B H C e m i s s i o n s ( p

p m )

Diesel

WPO Emulsion



Fig.10 - Variation of CO2 with Brake Power Fig.11 - Variation of HC emissions with Brake Power

8.2.4 Unburned Hydrocarbon emissions

Diesel exhaust hydrocarbons are composed of fuel molecules pyrolysis products of fuel

compounds and partially oxidized hydrocarbons (Pundir .B.P). Unburnt hydrocarbon is the direct

result of incomplete combustion of in the combustion chamber (Ganesan.V). It can be observed

from the Figure 11 that unburnt hydrocarbon emissions are more in the case of WPO diesel

emulsions due to more water content which leads to longer ignition delay and incomplete

combustion.




January 17-21, 2011

Jaipur, India

18

9. Conclusions

Pyrolysis process is a feasible method for bio-mass conversion into bio-oil. The bio-oil is a

complex mixture of several organic compounds. Preliminary tests were conducted with an

emulsion of WPO - diesel in a single cylinder diesel engine and the following results were

obtained from the experimental study:

• The brake thermal efficiency is higher for WPO-diesel emulsions compared to that of

diesel oil due lower viscosity of the emulsion and addition of ignition improver.

• The specific energy consumption is higher in the case emulsions; this is because of the

lower energy content of emulsion. Availability of more oxygen content in the fuel reduces

the heating value.

• The exhaust gas temperatures of different WPO diesel emulsions are higher than diesel fuel

operation. This is due to more oxygen availability in the pyrolysis oil and increased

combustion duration.

• The NO emissions are lower for WPO diesel blend due to more water content in the wood

pyrolysis oil which reduces the combustion temperature and with DEE addition operation

due to improved combustion rate the NO emissions are high.

• The CO emissions of WPO-diesel emulsions are slightly higher than diesel fuel due to poor

atomization of the emulsion.

• The unburnt hydrocarbon emissions are more in the case of WPO diesel emulsions due to

more water content and incomplete combustion.

10. Acknowledgements

The authors sincerely thank the Department of Science and Technology, Ministry of Science and

Technology, New Delhi for their financial grant (No.SR/S3/MERC/061/ 2009, Dt.02.09.2009) to

carryout this research work.




January 17-21, 2011 19

11. References

[1]. Roy G. D, Khanna Publications, (2004).

[2]. David Chiaramonti, Anja Oasmaa, Yrjo Solantausta, Renewable and Sustainable Energy

Reviews, Vol 11 (2007) 1056-1086.

[3]. Bridgwater A.V, Toft A.J, Brammer J.G, Renewable and Sustainable Energy Reviews, Vol 6

(2002) 181–248.

[4]. Bridgwater A.V, Biomass Vol 22 (1990) 279-292.

[5]. Ralph P. Overend, Biomass and bio energy, (2004)

[6]. Stefen Czernik, David K.Johnson and Stewart Black, Biomass and Bioenergy Vol 7, Nos. 1-6,

(1994)187-192.

[7]. Zhang Qi, Chang Jie, Wang Tiejun, Xu Ying, Energy Conversion and Management Vol 48

(2007) 87-92.

[8]. Dinesh Mohan, Charles U.Pittman, Jr., and Philip H. Steele, Energy & Fuels 2006, 20, 848-

889.

[9]. Yrjo Solantausta, Nils Olof Nylund, Marten Westerholm, Tiina Koljonen & Anja Oasmaa ,

Bioresource Technology Vol 46[1993] 177-188.

[10]. www.wikipedia.org.

[11].Frigo. S, Gentilli. R, Tognotti. L and Zanforlin. S, Benelli. G, SAE 982529.

[12] Bertoli. C, Alessio. J.D, Del Giacomo. N, Lazzaro. M, Massoli. P and Moccia. V, SAE 2000-

01-2975.

[13]. Michio Ikura,maria Stanciulescu and Ed Hogan, Biomass and bioenergy Vol 24, 221-

232, (2003).

[14]. Alahmer. A, Yamin. J, Sakhrieh. A, Hamdan. M.A, GCREEDER 2009, Amman Jordan,

March 31st – April 2nd 2009.

[15]. Chiramonti. D and et al., Biomass and bioenergy Vol 25, 85-99, (2003).

[16]. Murugan. S, Ramaswamy. M.C, Nagarajan. G, Fuel 87(2008), 2111-2121.

[17]. Shailendra Sinha P, Agarwal Avinash Kumar, ASME-Internal Combustion Engines Division,

Spring Technical Conference 2006, May 7-10, Germany.

[18]. Paul Degobert, Society of Automotive Engineers ISBN 2- 7108- 0676-2, pp 24

[19]. Mukunda .H.S, Universities Press [India] Private Limited Publication, ISBN .978 81 7371

685 0.

[20]. Ganesan.V, TMH Publication 2008, ISBN 10:0-07-064817-4.

[21]. Pundir .B.P. Narosa Publication 2007, ISBN 978-81-7319-819-9, pp 41.

manuscript prakash

Documents