Research Reports of Nagaoka National College of Technology Vol.46Ȫ2010ȫőŢűŦųKINEMATIC VISCOSITY OF MECHANICALLY EMULSIFIEDA-HEAVY OIL

Hiroki ISHIDA
Department of Electronic Control Engineering, Nagaoka National College of Technology
Abstract
Kinematic viscosity of the emulsified A-heavy oil, produced mechanically by a gear pump typemechanical emulsifier, was examined. The effects of some conditions for emulsification; thetemperature, the content of water and the revolution of driving gear of the emulsifier, on thekinematic viscosity were studied experimentally. The present study revealed some importantdependence of the kinematic viscosity on the running conditions of the gear pump type mechanicalemulsifier. The kinematic viscosity increases with increases in the water content and in the gear
revolution, but decreases with increase in the temperature of emulsion.
Key Words: W/O type emulsion, gear pump mechanism, kinematic viscosity, A-heavy oil

1. INTRODUCTION
In the recent several years, as same as in overabout thirty years ago, the technology of applicationof emulsion fuels to many boilers, furnaces anddiesel engines has attracted much attention from thepoint of view of the energy saving and of theprevention of atmospheric pollution caused by theexhaust from many combustion facilities. It is,mainly, due to the recent high cost of crude oil andto the prevalence of the national consensus of theprotection of environment.
The kind of emulsion fuels, consisting of usual
petroleum fuels and water, is divided into twotypes; W/O and O/W emulsions. W/O typeemulsion fuel has dispersed many fine waterparticles in the base petroleum fuel. On the otherhand, O/W type emulsion fuel has, inversely,
dispersed many fine petroleum fuel particles in thewater phase.
Many excellent studies on the combustion ofemulsified petroleum fuels in furnaces have beenreported experimentally1-4,8-17,21-23,25-32,34,37,38,41) andtheoretically 5-7,11,35).㩷 From the point of view of fire
hazard prevention also, some studies have reported
the pool burning characteristics of emulsified
petroleum fuels10,15, 18-20, 24, 36). An excellent review
by Kadota and Yamasaki has reported the recent
advances of the study on the emulsion
combustion40). In the recent decade, some studies
have reported the new technology for theemulsification of miscellaneous fuels33,39,41,42).
Since over twenty years ago, Nakayama has
devised and improved successfully an excellent
mechanical emulsification device using a gearpumping mechanism consisting of some specified
gears, which is described in his patent43). Thismechanical emulsification device gives a strong
shear stress to the mixture of water and petroleum
fuel in the squish among the rotating gears and in
the clearance between the gears and surrounding
housing wall. Water particles are thereby strongly
ground and mixed with base petroleum fuel, andsome of them become extremely fine (less thanabout 10㱘m in diameter), which cannot be attainedby the usual mechanical methods of mixing,
atomizing or both. This mechanical emulsification
device has enabled also the new recycling fueltechnology for some waste oils (from machine andfood) in boilers and many combustion furnaces.
Our previous paper has reported some important
performance of the gear pump type emulsification
device including the stability of emulsions ofA-heavy oil and gas oil44). Now the kinematic
viscosity of emulsified fuel also is an important
property for the characteristics of sprayed fuel jet
into many combustion furnaces. In general, thedecrease in the kinematic viscosity of fuel leads tothe wide-angle spray area and the short length offuel jet from the exit of nozzle. On the other hand,
the increase in the kinematic viscosity of fuel leads
to the long length of fuel jet from the exit of nozzle― 25 ―

Ijsplj!JTIJEB

although the spray area angle will decrease. The
present study reports the kinematic viscosity of theemulsified A-heavy oil, produced by the gear pump
type mechanical emulsifier44).

2. GEAR PUMP TYPE EMULSIFIER
The concept and the outline of the three gears
pump type mechanical emulsifier used in this study
are described in our previous paper44). Figs. 1 and2 show the top and the side views of the present
gear pump type emulsifier, where the first gear isdriven directly by motor at 300~1300 rpm. Thisemulsifier has a series of 3 gears: the diameters ofgear tip circle and pitch circle; 27.5~22.5 mm and25~20 mm respectively, the numbers of teeth;
20~16, the modules of gears; 1.25~1.23, the teeth
length in the axis direction of gears; 40 mm.
The clearance between the gear tip and thehousing wall; 0.05 mm for the first gear, 0.5 mm at
one side of the second gear, about 0.15 mm at one
side of the third gear and about 0.4 mm at theopposed side of the third gear. Owing to the verystrong shear stress in the wider clearances aroundthe second and the third gears, the fuel and water
are mixed and emulsified.

Fig.1 The scheme of top view of mechanical emulsifier(3-gears type) in this study.

Fig.2 The side view of mechanical emulsifier (3-gearstype) in this study.

Fig.3 Scheme of the water injection (Velocity: Vw )from the fine exit of nozzle to the first gear for theemulsification.

Fig.4 Schematic model of the emulsification region inthe clearance between the gear teeth and the housingwall.

Fig.5 Representative photograph of emulsified A-Heavy
oil (Water: 6 vol.% for Fuel, 800 rpm).

In the present mechanical emulsifier, water istransported by water pump and injected at highspeed (9~13 m/s) from the fine exit hole (0.7 mm india.) nozzle toward the first gear aiming to enhancethe emulsification effect, as shown in Fig.3. Fig.4
shows the schematic model of emulsification region
in the wider clearance (Emulsification Path shownin Fig.1) between the gear tip and the housing wall.
In this wider clearance (Emulsification Pathshown in Fig.1), the mixture of fuel and water istransferred (by the pressure due to the revolution of― 26 ―LJOFNBUJD!WJTDPTJUZ!PG!NFDIBOJDBMMZ!FNVMTJGJFE!B.IFBWZ!PJM

the first gear) in the opposite direction to therevolution of gear.
Although the theoretical explanation of thisemulsification mechanism is not easy and cannot begiven in the present stage, it should be noted that
there is no other region for the emulsification except
this wider clearance, where the very strong shear
stress exists. We can expect thereby that theincrease in the revolution of gear will enhance thestability of emulsion.
A typical W/O emulsified A-heavy oil is shownin Fig.5, where the water content is about 6 vol.%for A-heavy oil. As shown in this photograph, thecolor of W/O type emulsified A-heavy oil become
whitish compared with that of the original fuel.

3. KINEMATIC VISCOSITY
The kinematic viscosity of the w/O typeemulsified A-heavy oil in this study was measured
by usual Cannon-Fenske Viscometer, shown inFig.6. 㩷 By the elapsed time of flow down ofemulsion (T), from A to B shown in Fig.6, and thecharacteristic viscometer constant (C), the kinematicviscosity (Q of emulsified A-heavy oil can be
estimated as follows;Q PUm C7  Figs. 7, 8 and 9 show the effects of thetemperature, the water content and the revolution of
the first gear on the kinematic viscosity of the w/otype emulsified A-heavy oil respectively.
The density of emulsion (Um may be expressed
as follows, using the ratio of water in emulsion (W);Um UA (1-W)+UwW(2)

where UA is the density of A-heavy oil (0.85 g/cm3),and Uw is the density of water (1.0 g/cm3).
At the standard state (20oC), the kinematicviscosities (Q of water and A-heavy oil are about
1.0 (mm2/s) and 5.2 (mm2/s) respectively. From
the result shown in Fig.7, in addition to thetemperature dependence, we can see an interestingand important result that the kinematic viscosity ofW/O type emulsified A-heavy oil is slightly higher
than that of original A-heavy oil.
According to the Eq. (1), the viscosity ofemulsion also must increase simultaneously withincrease in the density of emulsion, which increases
with increase in the water content according to theEq. (2). Thus, the kinematic viscosity of emulsion
will increase slightly. This may be attributable tothe existence and the motion of many fine waterparticles.

where Pis the viscosity of emulsion, and Umis thedensity of emulsion.
Kinematic Viscosity (mm2/s)

6Emulsifier: 3 Gears Type
A-Heavy Oil

54Water Content : 3.0 vol.% ,800rpm

3A-Heavy Oil

21010Water
2030

4050

60

70

Temperature (oC)Fig.7 Effect of temperature on the kinematic viscosity.

Fig.6 Cannon-Fenske Viscometer.

From the results shown in Figs.8 and 9, we cansee clearly that both the increase in the watercontent and the increase in the gear revolution
increase the kinematic viscosity of emulsion.
The increase in the water content means theincrease in the number of fine water particles inemulsion, shown in Fig.10, and the increase in the― 27 ―

Ijsplj!JTIJEB

gear revolution will lead to the strong smash ofwater particles in the emulsification path, shown in
Fig.1, and to the extremely finer water particles inthe emulsion (Fig.10).
Thus, both the increase in the water content andthe increase in the gear revolution will increase thecontact surface area between the water and thehydrocarbon fuel.

Kinematic Viscosity (mm2/s)

4.5

4. CONCLUDING REMARKS

Emulsfier: 3 Gears Type
A-Heavy Oil
Temp. :30 oC

4.41200 rpm

1000

4.3

800

4.2
4.1
4.0

2

3456

78

910

Water Content (vol.%)

Fig.8 Effect of water content on the kinematic viscosity.

4.4

Emusfier: 3Gears Type
A-Heavy Oil
Temp: 30 oC

Water Content : 9 vol.%For the kinematic viscosity of the W/O typeemulsions of A-heavy oil, produced by the gearpump type mechanical emulsifier withoutsurface-active agent, the present study revealed
some interesting and important characteristics asfollows;(1) The kinematic viscosity of W/O typeemulsified A-heavy oil is higher than that oforiginal A-heavy oil, which may be due to theexistence of many fine water particles.
(2) Both the increase in the water content and theincrease in the gear revolution increase thekinematic viscosity of W/O type emulsified
A-heavy oil.
(3) The increase in the kinematic viscosity ofW/O type emulsion may be attributable to theincrease in the contact surface area between thewater and the original hydrocarbon fuel.

2Kinematic Viscosity (mm /s)

4.5

The increase in the contact surface area will
increase the kinematic viscosity of W/O typeemulsion. We can find many reports through theInternet, referring the increase in the kinetic
viscosity of emulsion due to the increase in thewater content and to the decrease in the size ofwater particles.

4.3
4.2

6 vol.%ACKNOWLEDGEMENTS

3 vol.%

The author would like to express his sincere
thanks to Mr. T. Nakayama, N-Techno Co., Ltd. forhis great help in constructing the experimental setup
and providing the gear pump type mechanicalemulsifier. Messrs. S. Sato and T. Abe areappreciated for their great help in conducting theexperiment.
The author is indebted for thefinancial support by Sasaki Environment
Technology Foundation through this study.

4.1
4.0
500

600

700

800

900

1000

1100

1200

1300

Revolution of the First Gear (rpm)Fig.9 Effect of revolution on the kinematic viscosity.

REFERENCES

Fig. 10 Microscopic Photograph of Water Particles in theEmulsified Gas Oil (Water: 9 vol.%, 800 rpm).

1) Dryer, F.L.: Water Addition to Practical Combustion
Systems-Concepts and Applications. Proc. Combust. Inst.,
Vol.16, pp. 279-295, 1976.
2) Sjorgen, A.: Burning of Water-in-Oil Emulsions, Proc.
Combust. Inst., Vol.16, pp. 297-305, 1976.
3) Jacques, M.T. et al.: The Combustion of Water-in-Oil
Emulsions and The Influence of Asphaltene Content, Proc.
Combust. Inst., Vol.16, pp. 307-319, 1976.
4) Hall, R.E.: The Effect of Water/Residual Oil Emulsions on
Air Pollutant Emissions and Efficiency of Commercial
Boilers, Journal of Engineering for Power, Transactions of― 28 ―

LJOFNBUJD!WJTDPTJUZ!PG!NFDIBOJDBMMZ!FNVMTJGJFE!B.IFBWZ!PJM

ASME October, pp. 425-433, 1976.
5) Jacques, M.T.: Transient Heating of a Emulsified
Water-in-Oil Droplet, Combustion and Flame, Vol.29, pp.
77-85, 1977.
6) Birchley, J.C. and Riley, N.: Transient Evaporation andCombustion of a Composite Water-Oil Droplet, Combustion
and Flame, Vol. 29, pp. 145-165, 1977.
7) Law, C.K.: A Model for the Combustion of Oil/WaterEmulsion Droplets, Comb. Sci. and Tech., Vol. 17, pp. 29-38,1977.
8) Cook, D.H. and Law, C.K.: A Preliminary Study on theUtilization of Water-in-Oil Emulsions in Diesel Engines,Comb. Sci. and Tech., Vol. 18, pp. 217-221, 1978.
9) Lasheras, J.C., et al.: Initial Observations on the Free
Droplet Combustion Characteristics of Water-in-FuelEmulsions, Comb. Sci. and Tech., Vol. 21, pp. 1-14, 1979.
10) Weatherford Jr., W.D., et al.: Army Fire-Resistant Diesel
Fuel, SAE Technical Paper Series, No. 790926, 1979.
11) Law, C.K., et al.: Combustion Characteristics ofWater-in-Oil Emulsion Droplets, Combustion and Flame,Vol. 37, pp. 125-143, 1980.
12) Jahani, H. and Gollahalli, S.R.: Characteristics of Burning
Jet A Fuel and Jet A Fuel-Water Emulsion Sprays,Combustion and Flame, Vol. 37, pp. 145-154, 1980.
13) Lasheras, J.C., et al.: On the Disruptive Burning of Free
Droplets of Alcohol/n-Paraffin Solutions and Emulsions,
Proc. Combust. Inst., Vol. 18, pp. 293-305, 1981.
14) Gollahalli, S.R., et al.: Combustion of Drops and Sprays ofNo.2 Diesel Oil and Its Emulsions with Water, Proc.
Combust.Inst., Vol. 18, pp. 349-360, 1981.
15) Law, C.K.: On the Fire Resistant Nature of Oil/WaterEmulsions, Fuel, Vol. 60, pp. 998-999, 1981.
16) Marrone, N.J., et al.: Internal Phase Size Effect on
Combustion of Emulsions, Comb. Sci. and Tech., Vol.33, pp.
299-307, 1983.
17) Yap, L.T., et al.: Disruptive and Micro-Explosive
Combustion of Free Droplets in Highly Convective
Environments, Comb. Sci. and Tech., Vol. 41, pp. 291-313,1984.
18) Ishida, H. and Iwama, A.: Ignition Characteristics of Gelled(O/W Emulsified) Petroleum Fuel Pool, Comb. Sci. andTech., Vol. 36, pp. 51-64, 1984.
19) Ishida, H. and Iwama, A.: Flame Spreading along theSurface of Gelled (O/W Emulsified) Petroleum Fuel Pool,Comb. Sci. and Tech., Vol. 36, pp. 65-82, 1984.
20) Ishida, H. and Iwama, A.: Flame Spread along Gelled (O/WEmulsified) Pool of High-Volatile Petroleum Fuel, Comb.
Sci. and Tech., Vol. 37, pp. 79-92, 1984.
21) Wang, C.H. and Law, C.K.: Microexplosion of Fuel
Droplets under High Pressure, Combustion and Flame, Vol.
59, pp. 53-62, 1985.
22) Kimura, M., et al.: Combustion behaviors of Emulsified
Petroleum and JP-4/N2H4 Droplets at Weightless and Free
falling Conditions, Comb. Sci. and Tech., Vol. 44, pp.
289-306, 1986.
23) Randrolph, A.L. and Law, C.K.: Time-Resolvedgasification and Sooting Characteristics of Droplets ofAlcohol/Oil Blends and Water/Oil Emulsions, Proc.
Combust. Inst., Vol. 21, pp. 1125-1131, 1986.
24) Ishida, H. and Watanabe, H.: Flame Suppression overLiquid Pool by W/O Emulsification, Comb. Sci. and Tech.,
Vol.71, pp. 145-154, 1990.
25) Adiga, K.C. and Shah, D.O.: On the Vaporization Behaviorof Water-in-Oil Microemulsions, Combustion and Flame, Vol.
80, pp. 412-414, 1990.
26) Chung, S.H. and Kim, J.S.: An Experiment on Vaporizationand Microexplosion of Emulsion Fuel Droplets on a Hot
Surface, Proc. Combust. Inst., Vol. 23, pp. 1431-1435, 1990.

27) Yamasaki, H. and Tsue, M.: Evaporation and Combustionof Emulsified Fuel, JSME Int’l J. (B), Vol. 36, pp.
677-681,1993.
28) Ballester, J.M., et al.: Detailed Measurements in Heavy Oil
and Oil/Water Emulsion Flames, Comb. Sci. and Tech., Vol.
106, pp. 383-391, 1995.
29) Tsue, M., et al.: Observation of Sooting Behavior inEmulsion Droplet Flame by Planar Laser Light Scatteringin Microgravity, Proc. Combust. Inst., Vol. 26, pp.
1251-1258, 1996.
30) Tsue, M., et al.: Statistical Analysis on Onset ofMicroexplosion for an Emulsion Droplet, Proc. Combust.
Inst. , Vol. 26, pp. 1629-1635, 1996.
31) Yamasaki, H., et al.: Time Histories of Water Contents in a
Burning Emulsion Droplet, Proc. The First Asia-PacificConf. on Combustion, pp. 603-606, 1997.
32) Tsue, M., et al.: Effect of Gravity on Onset ofMicroexplosion for an Oil-Water Emulsion Droplet, Proc.
Combust. Inst., Vol. 27, pp. 2583-2593, 1998.
33) Kufferath, A., et al.: Continuous Generation andAir-Assisted Atomization of Fuel Oil-Water-Emulsions,Comb. Sci. and Tech., Vol. 148, pp. 17-26, 1999.
34) Nachmoni, G. and Natan, B.: Combustion Characteristics ofGel Fuels, Comb. Sci. and Tech., Vol. 156, pp. 139-157,2000.
35) Leite, L.F.T. and Lage, P.L.C.: Modeling of Emulsion
Droplet Vaporization and Combustion Including
Microexplosion Analysis, Comb. Sci. and Tech., Vol. 157,
pp. 213-242, 2000.
36) Walavalkar, A.Y. and Kulkarni, A.K.: Combustion ofWater-in-Oil Emulsion Layers Supported on Water,Combustion and Flame, Vol. 125, pp. 1001-1011, 2001.
37) O-Barrera, R. and Vilasenor, R.: An Experimental study of
the Effect of Water Content on Combustion of Heavy Fuel
Oil/Water Emulsion Droplets, Combustion and Flame, Vol.
126, pp. 1845-1855, 2001.
38) Gong, J-S. and Fu, W-B.: A Study on the Effect of More
Volatile Fuel on Evaporation and Ignition for Emulsified
Oil, Fuel, Vol. 80, pp. 437-445, 2001.
39) Dantas, T.NdeC., et al.: New Microemulsion System using
Diesel and Vegetable Oils, Fuel, Vol. 80, pp. 75-81, 2001.
40) Kadota, T. and Yamasaki, H.: Recent Advances in theCombustion of Water Fuel Emulsion, Progress in Energyand Comb. Sci., Vol. 28, pp. 385-404, 2002.
41) Hernandez, J.F. and Morla, J.C.: Fuel Emulsions Using
Biomass Pyrolysis products as an Emulsifier Agent, Energy&Fuels, Vol. 17, pp. 302-307, 2003.
42) Wang, C.H. et al.: Combustion and Micro-explosion ofCollision-merged Methanol/Alkane Droplets, Proc.
Combust. Inst., Vol. 30, pp. 1965-1972, 2005.
43) Nakayama, T., International Patent Application, B01F 3/08
(2006.01), No. PCT/JP2005/022850 (WO 2007/069298 A1).
44) H. Ishida and K. Tachibana, A mechanical Emulsification
Technology of Petroleum fuels without Surface Active
Agent, Research Rep. of Nagaoka National College ofTechnology, Vol. 45, No.2, pp. 47-54, 2009.

― 29 ―(Received July 20, 2010)