Experiment with diesel spray

CHAPTER 4: RESULTS AND DISCUSSION

4.5 Experiment with diesel spray

media. In this experiment, an amount of the incident flux is reflected at the entrance and exit surfaces of the glass of fog while another amount is absorbed and the remainder is transmitted. Based on the results of the second power meter, there was a significant difference of average voltage between right side and the left side of the power meter. On the right side, the average voltages are recorded decreasing while on the left side, average voltages are increasing and decreasing. The increasing voltage reading at certain angles means that the LDR has detects some portion of the laser beam. Thus, a portion of the beam was scattered to the surrounding. The highest average voltage is recorded by the second power meter on the left side at angles of 60° and 70°.

After spraying the diesel through the nozzle, the laser source was turned on and voltage reading of power meter was taken for 90 seconds. Figure 4.13 shows the graph of voltage versus time when diesel spray was introduced at different pressures.

-'.5 4:1

15 10

0 10 ~0 30 40 50 60 70 so 90 100 Tlme(s)

~SO~P~~

... 100~PII 150kPa -laser on

Figure 4.13: Plot of voltage versus time of diesel spray

Based on the graph, the average voltage reading when the laser was turned on is 4.805 V which also denotes the maximwn voltage, Vo. When the diesel was sprayed at 50 kPa, the voltage reading is 4.509 V followed by 4.049 V for 100 kPa and 3.634 V for 150 kPa. From this result, it shows the decreasing of average voltage value when the pressure is being increased. Basically, increasing the pressure will increase the angle of spray, resulting in more particles is being absorb by the laser beam. Thus, the voltage reading of power meter will decrease due to lesser transmitted laser beam that will be detected by the LOR. The calculation for average diameter of diesel droplets is shown below:

From LDAIPDA measurement system, the diameter of droplets was obtained as tabulated below:

Table 4.5: Diameter of droplets of diesel spray Pressure (kPa) Diameter of droplets, D2o (pm)

50 715.33

The extinction cross section, (aJcan be calculated by assuming mean extinction efficiency equals to 2. The calculation is shown in equation below:

7[ - 2

a ^e

= 4

^X^Q^e^X^D20 ^(4.8)

4

^X²^{X (}^{0.07153 )}²

=

^8.0303 x 10-3cm²

Then, the number density of water droplets is obtained by inserting the calculated value of ere into the equation below. The negative sign is omitted because only the value of number density is considered. Tabulation of number density for 100 kPa and 150 kPa is shown below:

ln 4.509/

4.805 (8.0303 X 10-3)(10)

=

-0.79 droplets/cm³

=

0.79 droplets/cm³

(4.9)

Table 4.6: Tabulation of extinction cross section and number density for each diesel pressure

Water pressure (kPa) ^(Te(1 o·3cm2) Number density (droplets/cm³)

50 8.0303 0.79

100 8.2337 2.08

150 8.509 3.28

Number density can be described as the degree of concentration of particles within a space. Based on the calculation, number density recorded at 50 kPa is 0.79 droplets/cm³ while for I OOkPa, the number density is 2.08 droplets/cm³• The highest number density recorded is 3.28 droplets/cm³at 150 kPa. As pressure increases, the number density is also increases. This is due to the increasing angle of spray when the pressure is increases thus lead to more particles absorbing the laser beam and resulting higher number density recorded.

In order to prove the scattering effect, the experiment was set up the same as the previous experiment with fog. Below are the figures of average voltages displayed by the second power meter when the diesel pressure was 50 kPa:

so •

JO • • • • • • • • •

1 0

0 10 20 30 40 50 60 70 so ⁹⁰

Aneii!('J

Figure 4.14: Average voltage displayed by both power meters at angles to the right of the first power meter

50 •

.:!_:.

~ 50

~ 2S

•

_~_:?0

lS 10 OS 00

• • • ^..____ . _•

0 10 :o 30 40 50 60 70 so 90

Ao&~('J

When the laser beam is incident to the diesel spray, there will be reflections and transmittance of the beam by the particles to the surrounding. Based on the results of the second power meter, the highest average voltage recorded to the right side of the first power meter is 4.117 V at the angles of 70° while for the left side is 3.634 V at the angles of!0°.

CHAPTERS

CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions

The first experiment was to compare the warm up period of the laser where the new laser has higher value of voltage. Next was comparison of both power meters with new modified circuit that afterwards was proved reliable due to increment of voltage value. It was continued by experiment with smoke. This experiment was conducted to quantify the extinction coefficient of smoke. The highest extinction coefficient was obtained at 2 minutes which means the quickest beam that was being attenuated as it passes through the medium. The laser beam was incident to a Perspex container containing sea water and fresh water for third experiment which concern with absorbance value. The sea water had greater absorbance compared to fresh water as the voltage recorded was much lower. Next was experiment to study the scattering effect of fog. Last but not least was the experiment with diesel spray where the diesel atomization was introduced within the measurement system in order to quantify the number density.

The highest number density was obtained at lSOkPa. As the pressure of diesel was increased, more particles will absorb the laser beam due to higher angle of spray.

5.2 Recommendations

As for recommendations, improvements need to be done to the measurement system to increase its functionality and accuracy. For power meter, the casing could be improved so that light dependant resistor will not be too exposed to the light surrounding that could obstruct the voltage recorded. Hence, the circuit can be modified where the switch could be added for easy controlling. There are some difficulties occurred when changing the battery, thus, a design which is more friendly-user should be applied for the laser system.

More experiments should be done to deepen the understanding of the suspended particles. For instance, calculate the number density of solid particles for example wood dust. The wood dust could be varies by having different type of woods or different size of woods dust. Besides, experiments where two different lasers are used should also be implemented. The lasers should either have same power but different wavelength or vice versa From the experiments, the effect of wavelength or power could be analyzed. Fog is characterized as advection fog and radiation fog. The experiment with radiation fog could be done so that the result could be compared with the existing result of advection fog.

REFERENCES

Bradner,H. Attenuation of Light in Clear Deep Ocean Water, Institute of Geophysics &

Planetary Physics Scripps Institution of Oceanography, University of California, San Diego

David W. Hahn, Light Scattering Theory, Department of Mechanical and Aerospace Engineering University of Florida

George W. Mulholland, Mnny Y. Choi, Measurement of The Mass Specific Extinction Coefficient for Acetylene and Ethene Smoke Using Agglomerate Optics Facility, Department of Mechanical Engineering, University of Illinois at Chicago, Chicago

Ismail A.K.A. (20 1 0) Scattering Effects in Laser attenuation System for Measurement of Droplet Number Density, Final Year Project (FYP) Dissertation, Department of

Mechanical Engineering, Universiti Teknologi Petronas, Tronoh, Perak.

Interferometric Laser Imaging Droplet Sizer (ILIDS), 11th August 2008, Kanomax USA, retrieved 20 September 2010, from

http://www.kanomax.co.jp

Laser Doppler Velocimetry, 3'd August 2008 , Engine Research Laboratory of Michigan State University, retrieved 21 September 2010, from

http://www.egr .msu.edn!erl/ldv/ldv 1/ldv l.htm

Naser M. Ahmed, Zaliman Sauli, Uda Hashim, Yarub Al-Douri, Investigation of the absorption coefficient, refractive index, energy band gap, and film thickness for Al0.11Ga0.89N, Al0.03Ga0.97N, and GaN by optical transmission method, School of Microelectronic Engineering, Universiti Malaysia Pedis,

Phase Doppler Anemometry, 3'd August 2008, Department of Energy and Process Engineering, Tampere University of Technology, retrieved 22 September 2010, from

http://www.tut.fi/units/me/ener/laitteistot!EFD/PDA.html

Podzimek,J. Cloud and Aerosol Sciences Laboratory, University ofMissouri- Rolla,Rolla

Properties of green laser, retrieved 6 September 2011 from http: 1/ro bert.searchwam. com/ swa 1414 78.htm

Ray Optics Kit, Pasco, retrieved 7 November 2010 from www.pasco.com

Smoke, July 2010, retrieved 22 September 2010 from http://en.wikipedia.org/wiki/Smoke

Sources of attenuation, retrieved 16 August 2011 from http://www.ndt-

ed.org/EducationResources/CommunityCollege/Radiography/Physics/attenuation.htm

Sulaiman S. A. and Ismail A. K. A. A. " Scattering Effects in Laser attenuation System for Measurement of Droplet Number Density", Conference Paper, Department of Mechanical Engineering, Universiti Tekno1ogi PETRONAS, Tronoh, Perak.

Su1aiman S. A., Karim Z.A.A., Said M.A.M., Shaarani R.I.K.S. and M.Lawes "Light Extinction Technique for Measurements of Droplets in a Quiescent Fuel-Air Aerosol Mixture", Conference Paper, Department of Mechanical Engineering, Universiti Tekno1ogi PETRONAS, Tronoh, Perak.

APPENDIX I

EXPERIMENT TO COMPARE VOLTAGE READING OF BOTH POWER METERS

Voltage reading when laser is turned on and off:

Laser Turned Off Laser Turned On

First power Second power First power Second power

Time (s) meter meter meter meter

0 2.769 2.325 4.988 4.248

10 3.515 2.144 4.994 4.242

20 3.109 2.607 4.945 4.230

30 3.188 2.666 4.964 4.200

40 3.121 2.474 4.982 4.206

50 3.254 2.532 4.976 4.194

60 3.078 2.720 4.976 4.188

APPENDIX II

EXPERIMENT TO COMPARE VOLTAGE READING OF COVERED AND UNCOVERED LIGHT DEPENDENT RESISTOR

(LDR)

Voltage reading when LDR is covered and not covered:

Time Laser Turned Off Laser Turned On

(s) not covered covered not covered covered

2 3.475 0.243 4.971 4.883

4 3.474 0.283 4.959 4.873

6 3.526 0.298 4.951 4.863

8 3.576 0.248 4.94 4.844

10 3.476 0.248 4.926 4.824

12 3.576 0.248 4.906 4.800

14 3.526 0.248 4.913 4.771

16 3.526 0.298 4.926 4.76

18 3.576 0.298 4.885 4.751

20 3.526 0.199 4.878 4.747

APPENDIX III

EXPERIMENT Willi SMOKE

Average voltage reading of smoke:

Voltage reading (V) Time (s) With 2 minutes 4 minutes

container

0 4.680 4.049 4.143

10 4.680 3.888 4.252

20 4.701 4.064 4.167

30 4.677 3.846 4.188

40 4.692 4.085 4.198

50 4.695 4.028 4.152

60 4.680 4.049 4.143

The calculation of extinction coefficient:

At 2 minutes,

r ,. -

v fvc;;

-IIo -

^1.76

= 3.989/4.684 1.76

= 0.484

Taking Ms ⁼0.3529 (g/m3) L= 4.6m

1/Io= exp (-ks Ms L)

0.484 ⁼exp [ks (0.3529) (4.6)]

ks = 0.447

6 minutes 8 minutes 4.228 4.229 4.331 4.332 4.231 4.351 4.358 4.326 4.319 4.375 4.322 4.274 4.228 4.229

The total results are tabulated as below:

Intensity

Duration (minute) Average Voltage (V) 1/Io

2 3.989 0.484

4 4.166 0.505

6 4.297 0.521

8 4.303 0.522

Extinction coefficient

Duration (minute) Average Voltage (V) 1/10 Ks

2 3.989 0.484 0.447

4 4.166 0.505 0.421

6 4.297 0.521 0.402

8 4.303 0.522 0.401

APPENDIX IV

EXPERIMENT WITH SEA WATER

Average voltage reading:

Voltage reading (V)

Time (s) Empty container Fresh Water Sea Water

10 4.648 4.305 3.964

20 4.63 4.277 3.931

30 4.602 4.212 3.908

40 4.593 4.185 3.826

50 4.556 4.175 3.826

60 4.519 4.24 3.821

70 4.500 4.259 3.889

80 4.463 4.231 3.869

90 4.444 4.203 3.826

APPENDIXV

EXPERIMENT WITH FOG

Average voltage displayed by second power meter at angles to the right of the first power meter:

Time (s) Average voltage (V)

10 0.731

20 0.627

30 0.436

40 0.388

so

^0.347

60 0.400

70 0.42

80 0.42

90 0.467

Average voltage displayed by second power meter at angles to the left of the first power meter:

Time (s) Average voltage (V)

10 0.727

20 ^0.920

30 1.055

40 ^1.132

50 1.188

60 1.205

70 ^1.201

80 0.999

90 0.901

APPENDIX VI

EXPERIMENT WITH DIESEL SPRAY

Voltage reading during experiment of diesel spray at different pressures :

Time (s) Voltage reading (V)

Laser on 50kPa 100 kPa

10 4.796 4.675 4.015

20 4.83 4.566 4.09

30 4.842 4.639 3.963

40 4.83 4.569 4.079

50 4.83 4.567 3.986

60 4.807 4.483 4.021

70 4.807 4.478 4.108

80 4.802 4.512 4.073

90 4.79 4.49 4.125