FIELD OF THE INVENTION
The present invention relates to nano fluids based industrial coolants, in
particular coolant for interval combustion engine. More particularly, the present
invention relates to a process of producing industrial coolant by hydroxylation of
diesel soot particulates.
BACKGROUND OF THE INVENTION
A stable suspension of nanosized particles in a liquid is called nanofluid. A
nanofluid tends to be stable due to Brownian motion and the effects due to
functionalisation or surfactant. On the other hand, since the aggregation of
particles is driven by negative change in Gibbs energy, a nanofluid is never
stable. It has a general tendency to settle down over time due to aggregation of
the particles. These two opposing phenomena compete with each other and the
latter dominates. As a result, the nanofluid destabilises over a period of time
which can be very long as well. So, it can be said that the nanolfuids are
metastable. Since the solids have a thermal conductivity higher than that of
liquids, the nanoparticles enhance the thermal conductivity of the nanofluid.
Certain phenomena due to nano size effects of the nanoparticles, allow an
enhancement of the heat transfer coefficient. Even the shape and type of the
nanoparticles, are known to considerably affect the thermal properties. Various
materials that are used as nanoparticles for developing nanofluids, are:
• Metal oxides: alumina, titania, zirconia, ceric oxide, copper(II) oxide, etc.
• Metals: silver, copper, gold, nickel, cobalt, platinum, palladium, rhodium,
ruthenium, etc and their alloys
• Chalcogenides: like sulphides, tellurides, selenides.
• Magnetic materials
• Carbon allotropes: CNT, MWCNT, SWCNT, CNC, graphene, fullerenes.

• Ceramics: like nitrides, carbides, etc.
Development of nanofluids depends on the type of the base solution, type of
nanoparticles being used, their size requirement and the shape of the
nanoparticles (spherical, rod, disc, and triangles). Generally a nanofluid is
developed by two methods.
First method is a two step method, in which nanoparticles are prepared first and
then dispersed in a base fluid. But as the nanoparticles have a high surface
energy, aggregation and clustering of the nano particles are unavoidable and
appear easily. Afterwards, the particles get clogged and sedimented at the
bottom of the container. Thus, making a homogeneous dispersion by the two
step method remains a challenge. However, there exist some known techniques
to minimize this problem such as high shear and ultrasound. Nanofluids
containing oxide particles and carbon nanotubes are produced by this method.
This method works well for oxide nanoparticles and is especially attractive for the
industry due to its simple preparation method. However, due to quick
agglomeration of the particles this method entails multiple disadvantages. As the
nanoparticles disperse partially, dispersion is poor and sedimentation takes place.
Therefore, a high volume concentration of the fluid is needed which interalia
increases the heat transfer including the production cost.
A second method is a one step process in which nanoparticles are produced and
dispersed in the base fluid simultaneously. The single-step method is a process
combining the preparation of nanoparticles with the synthesis of nanofluids, for
which the nanoparticles are directly prepared by physical vapor deposition (PVD)
technique or a liquid chemical method (condensing nanophase powders from the
vapor phase directly into a flowing low-vapor-pressure fluid is called VEROS). In
this method drying, storage, transportation, and dispersion of the nanoparticles
are avoided, which minimizes the agglomeration of nanoparticles and increases
the stability of the nanofluids. A disadvantage of this method is that it is difficult

to scale it up for higher industrial production. Therefore, this method is
applicable only for low vapor pressure host fluids. This limits the application of
the method.
Due to high surface energy, nanoparticles have tendency to aggregate and settle
down in a nanofluid. However, if the surface of the nanoparticles is charged,
they are not aggregated. The surface charging of the nanofluids can be done by
two ways. In the first one, a suitable surfactant is mixed in the nanofluid. The
surfactant molecules get attached to the surface of the nanoparticles and form
micelles. These micelles of nanoparticle- surfactant have repulsive heads outside.
As a result, the nanoparticles don't aggregate. In the second method, the
surface of the nanoparticles is functionalised by means of a suitable process
(generally chemical). In this way nanofluids can be stabilised. However, high
temperatures, certain reagents, and high pressure of the function aliasing
process could affect the stability of the nanofluid significantly. The various
properties that are pertinent to the nanofluids for cooling application are thermal
conductivity, heat transfer coefficient, thermal diffusivity, specific heat, viscosity,
inertness and stability.
Nanofluids are in fact engineered colloids, and made of a base fluid and
nanoparticles (1-100 nm). Common base fluids include water, organic liquids
(e.g. ethylene, tri-ethylene-glycols, refrigerants, etc.), oils and lubricants, bio-
fluids, polymeric solutions and other common liquids. Materials commonly used
as nanoparticles include chemically stable metals (e.g. gold, copper), metal
oxides (e.g., alumina, silica, zirconia, titania), oxide ceramics (e.g. AI2O3, CuO),
metal carbides (e.g. SiC), metal nitrides (e.g. AIN, SiN), carbon in various forms
(e.g., diamond, graphite, carbon nanotubes, fullerene) and functionalized
nanoparticles. Solids have thermal conductivities which are in orders of higher
magnitude than those of conventional heat transfer fluids. By suspending
nanoparticles in conventional heat transfer fluids, the heat transfer performance
of the fluids can also be significantly enhanced. As a fluid class, nanofluids have

a unique feature which is quite different from those of conventional solid-liquid
mixtures in which millimeter and/or micrometer-sized particles are added. Such
particles settle rapidly, clog the flow channels, erode pipelines and cause severe
pressure drops. All these shortcomings prohibit application of conventional solid-
liquid mixtures to microchannels while nanofluids instead can be used in micro-
scale heat transfer. Furthermore, compared to nucleate pool boiling
enhancement by addition of surfactants, nanofluids can enhance the critical heat
flux (CHF) while surfactants normally do not. Thus, nanofluids appear promising
as coolants for dissipating very high heat fluxes in various applications. According
to the application, nanofluids are classified as heat transfer nanofluids,
tribological nanofluids, surfactant and coating nanofluids, chemical nanofluids,
process/ extraction nanofluids, environmental (pollution cleaning) [1]
Choi and Eastman proposed a method and apparatus for enhancing heat transfer
in fluids such as deionized water, ethylene glycol and oil by dispersing
nanocrystalline particles of substances such as copper, copper oxide, aluminum
oxide and the like in the fluids. Nanocrystalline particles are produced and
dispersed in the fluid by heating the substance to be dispersed in a vacuum while
passing a thin film of the fluid near the heated substance. Compared to those of
base fluids, the thermal conductivity of the nanofluids is increased up to 50
percent. [2]
Momoda and Phelps disclosed a nanofluid composition for enhanced heat
transfer fluid performance, comprising a base heat transfer fluid and a
nanometer sized phase change material (PCM). Introduction of nanometer sized
phase change material into the heat transfer fluid leads to improved, high
reversible thermal transport properties at elevated temperatures while ensuring
low viscosity of the fluid at a sub freezing temperatures. This invention relates to
the field of manufacturing of dielectric heat transfer fluids which can be pumped
at sub-freezing temperatures and at the same time have high reversible thermal
transport properties at temperatures up to 1200C. A method for preparing of

such a nanometer sized phase change material heat transfer fluid was also
disclosed. [3]
Maes et al. and Mae described nanofluids containing nano-particles and
carboxylates for improving the heat transfer characteristics of heat transfer fluids
or antifreeze coolants. The carboxylates from a stable physisorbedor
chemisorbed carboxylate protective layer on metallic nano-particles that does not
hinder heat transfer. The combination of carboxylates and metallic nano-particles
provide excellent corrosion protection, improved heat transfer and enhances the
stability of the nano-particles in suspension. [4, 5]
Tsujii and Egawa and Tsujii taught a heat transfer medium composition excellent
in dispersion stability of metal and/or metal oxide particles and high in the
thermal conductivity characterized by comprising water and/or alcohol as the
main component, and (a) one kind or two or more kinds selected from metal and
or/ metal oxide particles having an average particle diameter of from 0.001 to
0.1 urn, (b) one kind or two or more kinds selected from polycarboxylic acids
and/or salts thereof, and (c) at least one kind of a metal corrosion inhibitor. The
heat transfer medium liquid composition that can be used as a coolant for an
internal-combustion engine, a motor and the like, a heat transfer medium for a
hot water supply, heating, cooling and freezing system, or a heat transfer
medium for a snow melting system, road heating and the like. In particular, the
invention relates to a heat transfer medium liquid composition which is excellent
in dispersion stability of metal and or metal oxide particles and high in thermal
conductivity. [6, 7]
Yang and Han described a heat transfer fluid emulsion which includes a heat
transfer fluid, and liquid droplets dispersed within the heat transfer fluid, where
the liquid droplets are substantially immiscible with respect to the heat transfer
fluid and have dimensions that are no greater that about 100 nanometers. In
addition, the thermal conductivity of the heat transfer fluid emulsion is greater

the thermal conductivity of the heat transfer fluid. The nanoemulsion fluids of
the invention can conclude one or more conventional or other heat transfer fluids
having suitable thermal conductivities for a particular application. Exemplary heat
transfer fluid that can be used to form nanoemulsions in accordance with the
invention include, without limitation, liquid hydrocarbons such as substituted or
no substituted alkanes and polyolefins (e.g. aliphatic compounds including five or
more carbon atoms, aromatic compounds such as benzene and toluene, engine
oils, polyalphaolefins (POAs) etc.), mineral oils, antifreeze solutions (e.g.
ethylene glycol, propylene glycol, and diethylene glycol) and silicone oils,
fluorocarbon liquids and water (e.g. deionized water). Exemplary liquid
hydrocarbons are engine or motor oils (e.g. synthetic oils) that include
polyalphaolefin (POA) coumpounds. [8]
Hwang et al. suggested a heat transfer fluid with carbon nanocapsules. The heat
transfer fluid comprises a fluid and a plurality of carbon nanocapsules, uniformly
dispersed in the fluid, in an amount of 0.05 to 10% by weight. Particularly, the
carbon nanocapsules are modified to bond with at least one kind of functional
group, improving dispersiblity in the liquid. Thus, since the carbon nanocapsules
are apt to disperse in fluid and have superior thermal conductivity, the heat
conduction the capability of the heat transfer fluid therewith is enhanced. The
carbon nanocapsule may be hollow or filled with metals, metal oxide, metal
carbides, metal sulphide, metal nitride, metal borate or alloys. The fluid may be
water, alcohol or engine oil. [9]
Wu et al. taught a nanometer heat-conducting water solution for use in a car
cooling system. The solution is formed by mixing a AIO2 solution (1.1 vol%)
having 3-10 nanometer scale materials with a TiO2 solution (1.1 vol%) having 3-
10 nanometer scale material, where in the obtained solution is then mixed with a
diluent (93 vol%) and dispersing agents (3.43 vol%) and an emulsifying agent
(1.37 vol%) are thereafter added so as to disperse the AIO2 solution and Ti02
solution in the diluent uniformly. When the obtained stable nanometer heat-

conducting water solution is added to a water tank of the car, the TiO2 cleans
lime-scale and the emulsifying agent adheres to wall surfaces of water jackets to
allow AIO2 to release energy continuously. Moreover, the nanometer scale
materials speed up the micro-explosion of the cooling water so as to optimum
the cooling efect and increase the heat-dispersing efficacy significantly. [10]
As discussed in the published article, entiled "Study of mass spectroscopy
analysis of the diesel soot," by Vincent Carre et al., the following poly aromatic
hydrocarbons were found in diesel soot: phenathrene, fluoranthene Pyrene,
benz[a]anthracene, chrysene, benzo[a]pyrene, benzo[e]pyrene,
benzo[k]fluoranthene, perylene, benzo[ghi]perylene, indene[123-cdl] pyrene,
dibenzopentacene, tribenzopyrene and benzpchrysene [11]. Diesel engine soot
particles are chain aggregates composed of several of primary spherical particles.
Ishiguro et al. have found that the structure of such spherical particles comprises
of an inner core surrounded by an outer shell. The inner core of 0.010 urn is
composed of nonplanar molecules and outer shell is composed of micro
crystallites comprising several polycyclic aromatic hydrocarbon layers oriented
concentrically in a soot particle. During shell formation, molecules, radicals, or
ions including two to four carbon atoms could contribute the surface reactions
promoting the polycyclic growth of the graphitic crystallites [12].
OBJECT OF THE INVENTION
It is therefore, an object of the invention to propose a process of producing
industrial coolant by hydroxylation of diesel soot particulates.
SUMMARY OF THE INVENTION
The functionalized diesel engine soot is used for developing nano fluid engine
coolant. The functionalized diesel engine soot constitutes predominantly of nano
sized particles. The functionalization of diesel soot particulate matter (DPM) done
by hydroxylation method. After functionalization the DPM dissolve

homogeneously in polar solvents like water, ethylene glycol etc. The coolant
having functionalized DPM gives enhances thermal conductive and heat transfer
property.
According to the invention, a functionalized waste material is used to develop an
useful fluid for cooling application. During the combustion, in a Diesel engine,
soot or diesel particulate matter having particle size in nano range is produce,
which are used for nanofluid preparation.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - Hydroxylation of the diesel soot particulate matter
Figure 2(a) - Diesel soot particulate matter in polar solvent like water
Figure 2(b) - Shows hydroxylised Diesel soot particulate matter in polar solvent
like water.
Figure 3 - Particle size distribution of DPM
Figure 4 - SEM of DPM
Figure 5 - TEM of DPM
Figure 6 - Variation of relative thermal conductivity with % wt/vol
concentration in water-ethylene glycol.
Figure 7 - Variation of relative thermal conductivity of DPM in water with
concentration in wt/vol%
Figure 8 - Variation of relative heat transfer coefficient with concentration in
wt/vol% in water-ethylene glycol.
Figure 9 - Variation of relative dynamic viscosity of DPM in water-ethylene
glycol nano fluid with concentration.

DETAILED DESCRIPTION OF THE INVENTION
DPM (DIESEL PARTICULATE MATTER) OR DIESEL SOOT (DS)
During the combustion process in diesel engines, diesel particulate matter (DPM)
is produced due to incomplete and heterogeneous combustion, especially during
acceleration (during acceleration, more amount of fuel is supplied). The
particulate matter generally comprises carbon, Poly Aromatic hydrocarbons, and
a low amount of hydrocarbon. Carbon to hydrogen ratio is around 10. After
performing SEM, TEM, optical microscopy and XRD, it was found that DPM has
mean size distribution of particles around 40-45nm and is predominantly
amorphous. Considering its size, and associated experimental data, the present
inventors recognized DPM as a good candidate for nanofluid application. DPM
which has been used for the experimental work was extracted from an exhaust
duct of a diesel-electric loco. About 40 g of DPM was extracted from one exhaust
duct. Proper cleaning can yield much more DPM from the exhaust duct. Its true
density is around 2.1 g/cm3.
ETHYLENE GLYCOL
Ethylene glycol is an organic compound widely used as automotive antifreeze
(for elevation of boiling point and depression of freezing point) in cooling system.
In its pure form, it is an odourless, colourless, syrupy, sweet-tasting liquid.
Ethylene glycol is toxic, and ingestion can result in death. Due to its low freezing
point, the ethylene glycol resists freezing. A mixture of 60% ethylene glycol and
40% water freezes at -45 °C (-49 °F). Diethylene glycol behaves similarly.
Ethylene glycol is used as a de-icing fluid for windshields and aircraft.
The antifreeze capabilities of the ethylene glycol have made it an important
component of vitrification (anticrystallization) mixtures for low-temperature
preservation of biological tissues and organs.
However, Ethylene glycol disrupts hydrogen bonding when dissolved in water.

Pure ethylene glycol freezes at about -12 °C (10.4 °F), but when mixed with
water molecules, neither of the components can readily form a solid crystal
structure, and therefore the freezing point of the mixture is depressed
significantly. The minimum freezing point as observed when the ethylene glycol
percent in water is about 70%, and shown below. This is the reason that a pure
ethylene glycol is not used as an antifreeze, and water is a necessary component
as well.
PREPARATION OF NANOFLUIDS
Functionalized DPM based nanofluids
Application of DPM for nanofluid development is not found in prior art. Dissolving
the soot in water has been successful according to the invention.
Experiment
Preparation of Functionalized DPM based nano fluid
To prepare a nano fluid of DPM in a water-ethylene glycol base fluid, firstly,
sodium hydroxide was mixed in water enough to have Ph in the basic range
preferably above 9. Then the DPM was added to the mixture, and thoroughly
stirred (for 20min.) to hydroxylize the DPM. Then 50% by volume ethylene glycol
was added and stirred. Due to hydroxylation of the soot particulate, it dissolves
in the polar solvent. Also due to hydroxylation, the soot faces negatively charged
so it is not agglomerating (Fig 1).
As it is seen from Figure 2, the soot particulate matter is not dissolving in polar
solvent like water while after hydroxylation treatment the soot particulate is
easily dissolved in the polar solvent.
Nanofluid with concentration of 0.05, 0.1, 0.25, 0.5, 0.75, 1, 2.5 % wt/vol were
produced in a solution of water-ethylene glycol (1:1). During the test,
concentrates were prepared and then added to the base fluid in a coolant sump

of a heat transfer coefficient device for concentration of 0.25% wt/vol and
0.5%wt/vol only.
RESULT AND DISCUSSION
Nano coolant development
As discussed hereinabove on the experimental works, many attempts were made
to stabilise the DPM in the base fluid. It was found that stabilisation was
achieved only when a sufficient hydroxylation was done. When that happens, the
DPM nanoparticles become charged and remain suspended in a quite stable
manner.
Size distribution and nature of functionalized DPM
SEM and TEM were performed for DPM. It was found that DPM comprises
agglomerates of particles of size around 44nm (Fig 3). The SEM and TEM also
suggest the similar kind of particle size and agglomeration also (Fig.4 and 5)
Thermal conductivity analysis
The thermal conductivity was measured for
1) Functionalized DPM in water- ethylene glycol (W-EG) and
2) Functionalized DPM in water.
After the base fluids, concentrates were tested and they were diluted
subsequently to obtain solutions with lower concentration and then were tested.
The following are the trend with respect to the variation.
In Figures 6 and 7, Ks is the thermal conductivity for the nanofluid and Kb for
base fluid. From graph 1, it can be observed that thermal conductivity increases
for both the nanomaterials with the concentration. However, a sharp increase in
the thermal conductivity of DPM can be seen in water- ethylene glycol. In Figure
7, variation of thermal conductivity of DPM in water with varying concentration of

functionalized DPM can be observed. It is seen that there is a gradual increase in
the thermal conductivity. The trend depicted by DPM is quite encouraging.
Heat transfer coefficient measurement
Test of DPM in base fluid for concentration up to 0.5% wt/vol was done. The
following is the trend. See Fig 8. Significant increment in the heat transfer
coefficient observed.
In Figure 8, Hs is the heat transfer coefficient of nanofluid and Hb of the base
fluid. It can be seen that there is almost a linear increase in the relative values of
the heat transfer coefficient with the concentration.
Viscosity measurement
Viscosity for functionalized DPM nano fluids was measured. Figure 9 shows the
relative dynamic viscosity for DPM. It can be seen that viscosity at 0.5% is about
6% higher than the base fluid. However, viscosity is about 13 % higher at 0.75%
concentration and about 16 % higher at 1%.

References:
1. Lixin Cheng, Recent Patents on Engineering 2009, 3, 1-7, Nanofluid Heat
Transfer
Technologies, School of Engineering, University of Aberdeen, King's
College, Aberdeen, AB24 3FX, Scotland, UK
2. Choi, S.U.S., Eastman, J.A.: US20016221275B1 (2001).
3. Momoda, LA., Phelps, A.C.: US20026447692B1 (2002) and
WO0212413A2 (2002).
4. Maes, J.P., Lievenss, R.P.: EP1167486 Al (2002).
5. Maes, J.P.: US20050012069 Al (2005).
6. Tsujii, T.: EP1564 277A1 (2002).
7. Egawa, H., Tsujii, T.: US20050218370A1 (2005)
8. Yang, B., Han, Z.: US20070120088A1 (2007)
9. Hwang, G.L.: GB2432841A1 (2007)
10.Wu, C.J.: US20087374698 (2008)
11. Vincent Carre etal Anal. Chem., 2004, 76 (14), 3979-3987
12.T. Ishiguro, Y. Takatori, and K. Akihama, Combustion and Flame, 1997,
108, 231.

WE CLAIM
1. A process of producing industrial coolant by hydroxylation of diesel soot
particulate matter (DPM), the diesel soot particulate comprising polycylic
aromatic hydrocarbon and their derivatives such as phenathrene, fluoranthene,
pyrene, benzanthracene, chryasene, benzopyrene, benzo fluoranthene, perylene,
indenopyrene, fluoranthene dibenzopentacene, tribenzopyrene and
benzpchrysene.
2. The process as claimed in claim 1, wherein the hydroxylation involves
modification of the DPM so as to get dissolved in polar and non polar solvent by
the hydroxylation.
3. The process as claimed in claim 1, wherein the functionalised DPM concentration
in coolant is 0-20%.
4. The process as claimed in claim 1, wherein the particle size of the functionalized
DPM in the coolant varies from 5-100nm.
5. The process as claimed in claim 1, wherein the pH value of the coolant may vary
from 7-14, functionalizing of the diesel particulate materials (DPM) by dissolving
the DPM in a polar or non polar solvent to improve heat transfer properly
including thermal conductivity of the solvent, wherein the functionalizing the
DPM comprises preparing a nano-fluid of DPM by adding water-ethylene glycol
50% by volume to the DPM, and mixing sodium hydroxide in water to produce a
liquid having pH value above 7.
6. The process as claimed in any of the preceding claims, wherein a nano-fluid of
DPM with concentration of 0.05, 0.1, 0.25, 0.75, 1, and 2.5% wt/vol is produced
in a solution of water-ethylene glycol (1:1).

ABSTRACT

The invention relates to a process of producing industrial coolant by
hydroxylation of diesel soot particulates, the diesel soot particulate comprising
polycylic aromatic hydrocarbon and their derivatives such as phenathrene,
fluoranthene, pyrene, benzanthracene, chryasene, benzopyrene, benzo
fluoranthene, perylene, indenopyrene, fluoranthene dibenzopentacene,
tribenzopyrene and benzpchrysene.