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
An improved heat exchanger.
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S):
Saxena Amrita; of Crompton Greaves Limited, Machine (M7) Division, D-5, Industrial Area, MPAKVN, Mandideep - 462046, Madhya Pradesh, India; An Indian National.
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 electrical machines and equipment.
Particularly, this invention relates to the field of motors with corresponding heat exchangers.
More particularly, this invention relates to an improved heat exchanger.
BACKGROUND OF THE INVENTION:
A motor typically includes a rotor, a stator and associated assemblies, which assemblies are heat generating assemblies. There is a need to dissipate the heat for long life of the motor and so that the motor works according to specified standard.
Motors may be Closed Air Circuit Water Cooled (CACW), Closed Air Circuit Air Cooled (CACA) motors, High Tension (HT) motors, or Low Tension (LT) motors. Motors are susceptible to generate heat during its operative configuration. Due to the power it generates, heat output is a byproduct of the motor mechanism.
It is important that this generated heat i.e. hot air is guided appropriately away from the motor. For efficient working of motors, it is imperative that this byproduct of heat does not increase beyond defined thresholds. Hence, a ventilating or cooling system for such motors is necessary.
Heat Exchangers are deployed for efficient heat transfer from one medium to another. A fan is driven to extract relatively colder air from the surrounding

atmosphere into the heat exchanger. Guided through the conduits of the fan cover, the relatively colder air comes into contact with the relatively hotter air from the motor at the tubes, and the effective cooling of the ambient air around the motor and in the motor housing is carried out. Hence, relatively colder air records an increase in temperature due to transfer of heat. This hot air, now, is then exited through the heat exchanger in the surroundings.
There is a constant endeavour to improve the heat transfer characteristics in the heat exchanger such that efficient heat transfer occurs in the heat exchanger within the given length of the heat exchanger and the tubes which comprise the heat exchanger.
OBJECTS OF THE INVENTION:
An object of the invention is to provide improved or relatively increased heat dissipation with respect to a motor.
Another object of the invention is to provide a heat exchanger which allows improved cooling or heat transfer characteristics.
Yet another object of the invention is to provide higher ratings for motor due to increased heat dissipation capacity of an associated heat exchanger.
Still another object of the invention is to provide improved ventilation characteristics of a heat exchanger.

An additional object of the invention is to provide enhanced circulation of air through heat exchanger tubes.
SUMMARY OF THE INVENTION:
According to this invention, there is provided an improved heat exchanger comprising a plurality of contorted poly-sided tubes bundled together in a parallel configuration with respect to each other in order to allow entry of air from one end of the tubes which travels along the whole length in such a manner so as to create turbulence in the air flow.
Preferably, said tubes are hexagonal contorted tubes.
Typically, the sides of each of said poly-sided tubes are maintained parallel to the axis of each corresponding side.
Typically, each of said tubes includes a poly-sided cross section.
Typically, each of said tubes is made of a metal or other material with a high coefficient of heat transfer.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in
which:
Figure 1 illustrates a heat exchanger tube of a heat exchanger assembly of the prior
art;

Figure 2 illustrates a side view of a heat exchanger assembly; and
Figure 3 illustrates an isometric view of a heat exchanger assembly.
Figure 4 illustrates a heat exchanger tube of a heat exchanger assembly; and
Figure 5 illustrates a cross-section view of hexagonal contorted tube heat exchanger.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a heat exchanger tube of a heat exchanger assembly of the prior
art.
Figure 2 illustrates a side view of a heat exchanger assembly.
Figure 3 illustrates an isometric view of a heat exchanger assembly.
According to the prior art design, a heat exchanger (as referenced by numeral 150 in Figures 2 and 3 of the accompanying drawings) was comprised of a plurality of uniform or straight parallel aligned tubes (as referenced by numeral 100 in Figure 1 of the accompanying drawings).
Air flowing through these uniform tubes (100) is laminar air flow, which leads to a non uniform heat distribution in the cross section of the air passing through the tube. The air particles that are close to the surface of the tube absorb heat as they enter the tube. Due to the laminar flow the same air particles remain close to the tube surface and are not able to absorb more heat as they get saturated. On the other hand, the air particles which are flowing in the centre of the cross-section of

the tube are not subject to the tube surface and are not utilized completely. This results in inefficient heat transfer characteristics. And the full volume of incoming air through the tubes of the heat exchanger is not realised.
According to this invention, there is provided an improved heat exchanger.
Figure 4 illustrates a heat exchanger tube of a heat exchanger assembly.
In accordance with an embodiment of this invention, there are provided a plurality of contorted poly-sided tubes (200). The poly-sides may form a hexagonal tube or any tube with a pre-defined number of sides. The figure depicts a substantially hexagonal contorted tube. There are six sides. These sides are not operatively linear but are contorted, axially i.e. with respect to their own axis or length. A bundle of tubes aligned parallel to each other form the heat exchanger assembly. Even after the contortion, the edges between the sides of the poly-sided tubes were maintained parallel to the axis of each corresponding side.
The use of contorted poly-sided tubes results in creation of turbulence of air in the tube as it tries to pass through it. Due to this turbulence, the air particles near to tube surface and the air particles near to the center of the cross section of tube keep changing their positions, due to vortex formation, which enable them to absorb more heat uniformly. This results in better utilization of the air passing the tube at a given point of time.
By introducing contorted tubes in heat exchanger it is possible to increase heat transfer and achieve better cooling.

Figure 5 illustrates a cross-section view of hexagonal contorted tube heat exchanger. The contorted poly-sided (hexagonal, in this figure 5) tubes are stacked adjacent each other, row-wise and column-wise to form the heat exchanger tubes.
The technical advancement of this invention lies in provisioning of a contorted poly-sided tube, which results in better heat transfer, ventilation, and cooling through circulation due to creation of turbulence.
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. An improved heat exchanger comprising a plurality of contorted poly-sided tubes bundled together in a parallel configuration with respect to each other in order to allow entry of air from one end of the tubes which travels along the whole length in such a manner so as to create turbulence in the air flow.
2. An improved heat exchanger as claimed in claim 1 wherein, said tubes are hexagonal contorted tubes.
3. An improved heat exchanger as claimed in claim 1 wherein, the sides of each of said poly-sided tubes are maintained parallel to the axis of each corresponding side.
4. An improved heat exchanger as claimed in claim 1 wherein, each of said tubes includes a poly-sided cross section.
5. An improved heat exchanger as claimed in claim 1 wherein, each of said tubes is made of a metal or other material with a high coefficient of heat transfer.