FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A nanofluid based heat exchanger
APPLICANTS:
Crompton Greaves Limited, CG House, Dr. Annie Besant Road, Worli, Mumbai -400030, Maharashtra, India, an Indian Company
INVENTORS
Chaudhari Sushil Ekanath of Crompton Greaves Ltd, High Voltage Product Technology Centre CG Global R&D Centre, Kanjurmarg (E), Mumbai 400042, Maharashtra, India; and Bhattacharya Subhendu; of Crompton Greaves Ltd, Advanced Materials and Processing Technology Centre, CG Global R&D Centre, Kanjurmarg (E), Mumbai 400042, Maharashtra, India; both Indian Nationals.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of this invention and the manner in which it is to be performed.

FIELD OF THE INVENTION:
This invention relates to the field of Transformers
Particularly, this invention relates to heat exchangers and power transformers.
More particularly, this invention relates to a nanofluid based heat exchanger.
BACKGROUND OF THE INVENTION:
Transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF), or "voltage", in the secondary winding.
Cooling of transformers is effected by adjunct mechanisms such as heat exchangers, radiators, and the like assemblies, which work of thermal exchange principles and involve the use of coolants including air, water, oil, and the like.
Transformer, made up of iron and copper, has energy losses. These are reflected in the form of heat which increases the system temperature. Increase in heat results in heating of copper windings and increase in resistance, thereby reducing the operating ability of the transformer. There is a limiting temperature for transformers, which is set by use of solid insulation having acceptable working life around 100°C. So, efficient cooling is essential to increase the transformer's life, which is served by transformer oil.

Transformer, during its operation, generates heat in the winding, and that heat is transferred to the oil. Heated oil then flows to the radiators by convection and or forced by pumps, where oil cooling is carried out and the oil supplied from the radiators cools the winding, thus dissipates the heat. So it is important that the transformer oil should have high thermal conductivity.
Cooling of oil in transformers involves the use of radiators which have finned surfaces. A forced air draft is used to cool the oil inside the tubes. The current radiator used for oil cooling is bulky which increases the size of the transformer. Also additionally, a lot of the aero acoustic noise is generated from the fans used for transformer oil cooling.
OBJECTS OF THE INVENTION:
An object of the invention is to provide an effective heat transfer mechanism for cooling electrical equipment.
Another object of the invention is to provide an effective coolant which can be used in heat exchangers of coolants, the coolant being able to provide relatively increased heat transfer characteristics.
Yet another object of the invention is to enhance cooling of electrical equipment such as transformers.
Still another object of the invention is to maintain rated temperatures of the transformer.
An additional object of the invention is to preserve useful life of a transformer.

Yet an additional object of the invention is to reduce the carbon emission from a transformer and heat exchanger assembly.
Still an additional object of the invention is to remove or reduce aero acoustic noise from radiators of transformers.
SUMMARY OF THE INVENTION:
According to this invention, there is provided a nanofluid based heat exchanger
system adapted to regulate associated transformer temperature, said system
comprises:
nanofluid cooling system adapted to be coupled with said heat exchanger system
for allowing flow of cooled nanofluids into said heat exchanger and for receiving
heated nanofluids to be cooled by a compressor, in a feedback loop.
Typically, said heat exchanger is a shell and tube type heat exchanger.
Typically, said heat exchanger is a shell and tube type heat exchanger and said nanofluid cooling system includes outlet means to allow outflow of nanofluids to shell of said heat exchanger.
Typically, said heat exchanger is a shell and tube type heat exchanger and said nanofluid cooling system includes inlet means to allow inflow of nanofluids from shell of said heat exchanger.
Typically, said heat exchanger is a shell and tube type heat exchanger comprising the use of two fluids; a first fluid being oil which flows through said tubes and a second fluid being a nanofluid which flows through said shell.

Typically, said nanofluid is water with nanoparticles.
Typically, said nanofluid is water with nanoparticles selected from a group of nanoparticles consisting of copper nanoparticles, aluminum nanoparticles, carbon nanotubes (CNT), and their combinations.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates a schematic of a heat exchanger; and
Figure 2 illustrates a transformer system along with heat exchanger cooling system.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
According to this invention, there is provided a nanofluid based heat exchanger. Figure 1 illustrates a schematic of a heat exchanger.
The heat exchanger (100), shown, is a shell and tube type heat exchanger. It is the most common type of heat exchanger in oil refineries and other large chemical processes, and is suited for higher-pressure applications. It mainly comprises a bundle of tubes as referenced by numeral (8), inside a shell (7) which is a large pressure vessel. Two fluids, of different starting temperatures, flow through the heat exchanger. One fluid runs through the tubes, and another fluid flows over the tubes (through the shell) to transfer heat between the two fluids. There are often baffles (6) directing flow through the shell side so the fluid does not take a short

cut through the shell side leaving ineffective low flow volumes. These are generally attached to the tube bundle rather than the shell in order that the bundle is still removable for maintenance. Mounting brackets (5) for mounting of the heat exchanger (100) are shown. The ends of each tube are connected to plenums through holes in tubesheets (2) present at the head (4) of the heat exchanger (100). A gasket (3) is provided between the head (4) and the tubes (8). Reference numeral (1) refers to connections which allow shell-side fluid to flow in.
Figure 2 illustrates a transformer system along with heat exchanger cooling system.
The cooling system of a power transformer (52) includes a heat exchanger (100) in a feedback loop with the power transformer (52). This heat exchanger, is typically a shell and tube type tube exchanger, as illustrated in Figure 1 of the accompanying drawings, and as explained above. Oil (54) flows from the power transformer (52), through the heat exchanger (100), and back to the power transformer (52), after getting cooled in the heat exchanger (100).
This shell and tube type heat exchanger (100), as shown in Figure 1 of the accompanying drawings) comprises the use of two fluids; a first fluid which flows through the tubes and a second fluid which flows through the shells.
In accordance with an embodiment of this invention, there is provided a nanoparticle fluid cooling system (200) adapted to allow cooled nanofluids (62) to be fed to the heat exchanger (100) and to receive heated nanofluids (64) from the heat exchanger (100) in a feedback loop.
The nanofluid is comprised of water with nanoparticles. The nanoparticles may be

copper nanoparticles or aluminum nanoparticles or carbon nanotubes (CNT) for enhancing the cooling of transformer. The nanofluid cooling system is adapted to allow flow of nanofluids through the shell (1, Figure 1) of the heat exchanger (100).
The nanoparticles, in water, flow through the shell of heat exchanger and the oil through tube bundles. The oil carries the heat from windings and the heat is dissipated by nanofluids. The oil and nanofluid circuits come in indirect contact at the heat exchanger unit and heat from the transformer oil is dissipated to the nanofluid in the heat exchanger unit. This heat absorbed by the nanofluids, again, dissipates through the nanofluid cooling system (200). A compressor (220) is provided which cools the nanofluids in the nanofluid cooling system (200).
The nanofluids have high surface area and also have high thermal conductivity and hence, effective heat transfer can be established. Hence, a very compact heat exchanger can be designed for cooling power transformers which incorporates the use of nanofluids. The benefits include reduction is size of the power transformer along with noise reduction and improvement in life of power transformers.
Also additionally, a lot of the aero acoustic noise is generated from the fans used for transformer oil cooling which can removed if nanofluids are used in radiators.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A nanofluid based heat exchanger system adapted to regulate associated transformer temperature, said system comprising:
nanofluid cooling system adapted to be coupled with said heat exchanger system for allowing flow of cooled nanofluids into said heat exchanger and for receiving heated nanofluids to be cooled by a compressor, in a feedback loop.
2. A system as claimed in claim 1 wherein, said heat exchanger is a shell and tube type heat exchanger.
3. A system as claimed in claim 1 wherein, said heat exchanger is a shell and tube type heat exchanger and said nanofluid cooling system includes outlet means to allow outflow of nanofluids to shell of said heat exchanger.
4. A system as claimed in claim 1 wherein, said heat exchanger is a shell and tube type heat exchanger and said nanofluid cooling system includes inlet means to allow inflow of nanofluids from shell of said heat exchanger.
5. A system as claimed in claim 1 wherein, said heat exchanger is a shell and tube type heat exchanger comprising the use of two fluids; a first fluid being oil which flows through said tubes and a second fluid being a nanofluid which flows through said shell.
6. A system as claimed in claim 1 wherein, said nanofluid is water with nanoparticles.

7. A system as claimed in claim 1 wherein, said nanofluid is water with nanoparticles selected from a group of nanoparticles consisting of copper nanoparticles, aluminum nanoparticles, carbon nanotubes (CNT), and their combinations.