Experimental Investigations On A Diesel Engine

Published Date: 02 Nov 2017

MULTIWALLED CARBON NANOTUBES BLENDED BIODIESEL FUELS

Prajwal Tewari

, Eshank Doijode

, N.R. Banapurmath

2

, V.S. Yaliwal

3

1Students,

2

Professor, B.V.B. College of Engineering and Technology, Hubli 580031, India

3

Assistant Professor, S.D.M. College of Engineering and Technology, Dharwad 580 002, Karnataka, India

Corresponding author: [email protected], [email protected]

ABSTRACT

Experimental investigations were carried out to determine performance, emission, and combustion characteristics of

diesel engine using multi walled carbon nanotubes (MWCNTs) blended biodiesel fuels. The fuel combinations used for

the study were neat diesel for base line data generation, and CNT blended –biodiesel. The biodiesel was prepared from

honge oil called Honge Oil Methyl Ester [HOME]. The MCNTs were blended with the biodiesel fuel in the mass

fractions of 25 and 50 ppm with the aid of a mechanical homogenizer and an ultrasonicator. Subsequently, the stability

characteristics of MWCNT blended –biodiesel fuels were analyzed under static conditions.

The investigation were carried out using an experimental set-up consisting of a single-cylinder diesel engine coupled

with an eddy current dynamometer loading device, an MRU 1600s five gas analyzer, a Hartridge smoke meter, and a

data-acquisition system comprising a high pressure piezoelectric pressure sensor and a crank angle encoder. All the

experiments were conducted at a constant speed of 1500 rpm and the results revealed that a considerable enhancement

in the brake thermal efficiency and substantial reduction in the harmful pollutants due to the incorporation of MWCNTs

in the biodiesel fuels were observed.

Keywords: Carbon nanotubes, Ignition delay, Diesel engine, Honge oil, HOME, Biodiesel, Ultrasonicator, Emission.

1. INTRODUCTION

The diesel engines are considered to be fuel efficient

and sturdier than gasoline engines. However, they

produce hazardous emissions such as oxides of nitrogen

(NOx), particulates of matter, smoke, and obnoxious

odour in high magnitudes. To ameliorate the

performance and to reduce the emissions from the diesel

engines, various techniques such as fuel modification,

engine design alteration, exhaust gas treatment, etc.

have been tried. Several researchers have contributed

their efforts on fuel modification techniques in which

some chemical reagents are incorporated along with the

conventional diesel fuel. One of the fuel modification

techniques is the water–diesel emulsion, which

comprises diesel, water, and surfactant in specific

proportions. The water in the emulsion is suspended in

the fuel by a suitable surfactant and does not allow the

water to come into direct contact with the engine

surface [1]. Many researchers have reported on various

nano–particles for diesel engine applications. In view of

this, many new approaches and advances in

nano-technology are being directed to use nano-fuel as a

potential secondary energy carrier [2]. Nano particle

blended fuels are known to exhibit significantly

different thermo physical properties when compared to

base fuels. At nano meters scale the surface – area -tovolume ratio of the particle increases considerably and

this enables a larger contact surface area during rapid

oxidation process [3]. For instance, due to

size-dependent properties, energetic materials

containing nano-particles can release more than twice

the energy of even the best molecular explosives [4].

Several studies have reported lower melting points and

lower heats of fusion for decreasing sizes of metal

particles [5, 6, 7]. Yetter et al. [8] have critically

reviewed the reports on metal nano-particles

combustion and revealed that the nano-size metallic

powders possess high specific surface area and potential

to store energy, which leads to high reactivity. In their

detailed report on nano-particle combustion, they have

stated that adding nano-catalyst to the hydrocarbon

fuels (such as diesel) will reduce the ignition delay and

soot emissions.

2. USE OF MULTIWALLED CARBON NANO

TUBES (MWCNT’s)

Marquis and Chibante’s [10] work on carbon

nano-tubes (CNT) indicated that the suspended CNT in

a base fluid will enhance the surface-area-to-volume

ratio and settling time. Based on the above literature on

the potential applications of CNT, Sadhik Basha and

Anand [11] have experimentally investigated the

performance and the emission characteristics of a diesel

engine using CNT blended diesel. They observed a

substantial enhancement in the brake thermal efficiency © IJETAE2013 73 ICERTSD2013-04-201

Int. J Emerging Technology and Advanced Engineering

ISSN 2250-2459, Volume 3, Special Issue 3: ICERTSD 2013, Feb 2013, pages 72-76

and reduced harmful pollutants compared to that of neat

diesel. This is assumed to be due to better combustion.

The same team have critically reviewed the applications

of nano-particle/nano-fluid in diesel engines and

concluded that adding suitable proportion of

nanoparticles/CNT to the conventional fuels such as

diesel will reduce the evaporation time, which in turn

favours shorter ignition delay. Owing to the potential

properties of nano-particles/CNT, the present work is

aimed at establishing the effects on the performance,

emission, and combustion characteristics of a

single-cylinder, direct-injection diesel engine using

CNT blended water–diesel emulsion fuel. Therefore,

nano-particles can function as a catalyst and an energy

carrier, as well. In addition, due to the small scale of

nanoparticles, the stability of the fuel suspensions

should be markedly improved.

Recently, Sajith et al. [9] conducted an experiment in

single-cylinder diesel engine by dosing ceria

nanoparticles (20–80 ppm) to the jatropha biodiesel and

found a significant reduction in NOx and HC levels, and

improvement in the brake thermal efficiency. They also

observed that adding ceria nano-particles to the base

fuel acts as an oxygen buffer, which leads to high

catalytic combustion activity owing to their enhanced

surface-area-to-volume ratio characteristics [8]. Kao et

al. [7] carried out an experimental investigation in a

single-cylinder diesel engine using aluminium

nanoparticles blended diesel with varying water

concentration and found significant improvement in the

performance characteristics and substantial reduction in

the harmful pollutants level of smoke and NOx due to

the effect of improved combustion [9].

3. EXPERIMENTAL SET UP

The experimental investigations were carried out in two

phases. In the first phase, the various physicochemical

properties of modified bio diesel were determined and

compared with those of the base fuels. The properties

studied were the flash point, kinematic viscosity,

calorific value, pour and cloud points. In the second step

extensive performance, combustion and emission tests

were conducted on a single cylinder four stroke direct

injection compression ignition engine using the

modified and base fuels. Figure 1 shows the schematic

experimental set up. Eddy current dynamometer was

used for loading the engine. The fuel flow rate was

measured on the volumetric basis using a burette and

stopwatch also. The emission characteristics were

measured by using HARTRIDGE smoke meter and

AVL make equipment during the steady state operation.

The tests were conducted with diesel, and HOME –

nano particle blends combination and compared with

diesel operation. The specification of the compression

ignition (CI) engine was given in Table 1. Injection

timing and injection pressure for diesel and HOME –

MWCNT operation are kept at their optimum

conditions, viz. 23° BTDC and 230 bar for diesel and

19 ° BTDC, 230 bar for HOME- MWCNT blend. The

method of preparation of the fuels with the MWCNT

along with the experimental methods for obtaining the

fuel properties are given in the Table 2 and 3.

Fig. 1 Experimental set up

Table 1 Specification of test rig

Table 2 Material properties of nano – particle

samples used in this study.

Sl.no Parameters CNT

1 Manufacturer Intelligent Pvt.

Ltd

2 Bulk/ true density – g/cc 0.05 – 0.17

3 Average particle size (APS)

- nm

10 – 30

Length - 1–2 µm

4 Surface area (SSA) m

2

/g 350

5 Purity - % 95

Table 3 Properties of HOME - nano – particle blend

samples used in this study

Type of fuel Density @15

o

C

Diesel 840

HOME 880

HOME25CNT 898

HOME50 CNT 900

Sl

No

Engine specification

Parameters Engine

1 Type of engine Kirlosker make Single

cylinder four stroke direct

injection diesel engine

2 Nozzle opening

pressure

200 to 205 bar

3 Rated power 5.2 KW (7 HP) @1500 RPM

4 Cylinder diameter

(Bore) 87.5 mm

5 Stroke length 110 mm

6 Compression

ratio

17.5 : 1© IJETAE2013 74 ICERTSD2013-04-201

Int. J Emerging Technology and Advanced Engineering

ISSN 2250-2459, Volume 3, Special Issue 3: ICERTSD 2013, Feb 2013, pages 72-76

4. HOME – MWCNT BLENDS PREPARATION

In the first step, the CNT are weighed to a

predetermined mass fraction of 25ppm and dispersed in

HOME (5 per cent by volume) using ultrasonicator set

at a frequency of 40 kHz, 120W for 30 min. This, the

CNT blended – HOME fuel is prepared and the same

process is carried out for the mass fraction of 50ppm

CNT blended biodiesel fuel.

5. RESULTS AND DISCUSSIONS

During the experiment, injection timing, injection

opening pressure and compression ratio were kept at 23

o

BTDC, 205 bar and 17.5 for diesel operation and 19

0

BTDC, 230 bar and 17.5 for HOME – MWCNT blend

respectively.

5.1 VARIATION OF BRAKE THERMAL

EFFICIENCY

Fig. 2 shows variation of brake thermal efficiency for

HOME and HOME-MWCNTs blended fuels. The

HOME operation resulted in inferior performance due

to its higher viscosity (nearly twice diesel) and lower

volatility and lower calorific value.

However the brake thermal efficiency of the

MWCNTs-HOME blended fuels was observed to be

better compared to neat HOME operation. This could

probably be attributed to the better combustion

characteristics of MWCNTs. In general, the nanosize

particles possess high surface area and reactive surfaces

that contribute to higher chemical reactivity to act as a

potential catalyst [22]. In this perspective, the catalytic

activity of MWCNTs could have improved due to the

existence of high surface area and active surfaces.

Moreover, in case of HOME50MWCNT fuel, the

catalytic activity may be enhanced due to the high

dosage of MWCNT compared to that of

HOME25MWCNT. Due to this effect, the brake

thermal efficiency is higher for HOME50MWCNT

compared to that of HOME25MWCNT. The maximum

brake thermal efficiency for HOME50MWCNT is

25.0% whereas it is 24% for HOME25MWCNT,

compared to 23% for HOME and 28% for neat diesel, at

the 80% load respectively.

Fig. 2 Variation of brake thermal efficiency with brake

power

5.2 VARIATION OF SMOKE OPACITY

The smoke opacity for HOME and HOME-MWCNTs

blended fuels shown is shown in Fig. 3. The HOME

operation resulted in higher smoke opacity compared to

diesel due to its heavier molecular structure and lower

volatility. However reduced smoke opacity is observed

in the case of MWCNTs-HOME blended fuels. This

could be attributed to shorter ignition delay

characteristics of MWCNTs-HOME blended fuels. The

smoke opacity for HOME50MWCNT is 59 HSU

whereas it is 63 HSU for HOME25MWCNT, compared

to 78 HSU for HOME and 52 HSU for neat diesel, at the

80% load respectively.

Fig. 3 Variation of smoke opacity with brake power

5.3 VARIATION OF HC EMISSION

The unburnt HC emissions for HOME and

HOME-MWCNTs blended fuels are shown in Fig. 4.

The HC emission for HOME operation is higher

compared to diesel due to its lower thermal efficiency

resulting in incomplete combustion.

Type of fuel Flash

point,

o

C

Kinematic

Viscosity, cSt

@ 40

o

C

Net

calorific

value,

MJ/kg

Diesel 56 2 -3 43

HOME 170 5.6 36.016

HOME25CNT 166 5.7 34.56

HOME50 CNT 164 5.8 35.10© IJETAE2013 75 ICERTSD2013-04-201

Int. J Emerging Technology and Advanced Engineering

ISSN 2250-2459, Volume 3, Special Issue 3: ICERTSD 2013, Feb 2013, pages 72-76

However HC emissions are marginally lower for the

HOME-MWCNTs blended fuels than HOME. This

could be due to catalytic activity and improved

combustion characteristics of MWCNT, which leads to

improved combustion.

The HC emission for HOME50MWCNT is 58 PPM

whereas it is 70 PPM for HOME25MWCNT, compared

to 82 PPM for HOME and 32 PPM for neat diesel, at the

80% load respectively.

Fig. 4 Variation of hydrocarbon with brake power

5.4 VARIATION OF CO EMISSION

The CO emissions for HOME and HOME-MWCNTs

blended fuels are shown in Fig. 5. The CO emission for

HOME operation is higher compared to diesel due to its

lower thermal efficiency resulting in incomplete

combustion.

However CO emissions are marginally lower for the

HOME-MWCNTs blended fuels than HOME. The

higher catalytic activity and improved combustion

characteristics of MWCNT, leading to improved

combustion could be the reason for this performance.

CO emissions for HOME50MWCNT are 0.21%

whereas it is 0.3% for HOME25MWCNT, compared to

0.45% for HOME and 0.1 for neat diesel, at the 80%

load respectively.

Fig. 5 Variation of carbon monoxide with brake power

5.5 VARIATION OF NOX EMISSION

Fig. 6 shows variation of NOx emission for HOME and

HOME-MWCNTs blended fuels. For HOME operation

NOx emissions were lower as compared to diesel

operation. Heat release rates of HOME were lower

during premixed combustion phase, which will lead to

lower peak temperatures. Nitrogen oxides formation

strongly depends on peak temperature, which explains

the observed phenomenon. Furthermore,

HOME-MWCNTs blended fuels produced higher NOx

emission compared to that of HOME. This is because

of reduced ignition delay that resulted in higher

premixed combustion fraction and higher peak

temperatures observed with HOME-MWCNT blends.

The NOx emission for HOME50MWCNT is 750 PPM

whereas it is 600 PPM for HOME25MWCNT,

compared to 580 PPM for HOME and 800 PPM for neat

diesel, at the 80% load respectively.

Fig. 6 Variation of nitric oxide with brake power

6. CONCLUSIONS

The performance, and the emission characteristics of

HOME HOME-MWCNTs blended fuels were

investigated in a single-cylinder, constant speed,

direct-injection diesel engine.

Based on the experimental data, the following

conclusions have been drawn.

1. The brake thermal efficiency HOME-MWCNTs

blended fuels were relatively better as compared to

that of HOME.

2. HOME operation resulted in poor performance in

terms of increased smoke, HC, CO emissions as

compared to neat diesel operation.

3. The NOx emissions were relatively less for HOME

as compared to that of HOME-MWCNTs blended

fuels operation.

4. Ensuring higher dispersion of MWCNTs in HOME

is still a subject of research. The study is limited to

maximum of 50 ppm of MWCN