FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
HEAT EXCHANGER;
BLUE STAR LIMITED, A COMPANY INCORPORATED UNDER COMPANIES ACT 1956, WHOSE ADDRESS IS KASTURI BUILDINGS, MOHAN T. ADVANI CHOWK, JAMSHETJI TATA ROAD, MUMBAI- 400 020 MAHARASTRA, INDIA;
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE INVENTION
The present invention relates to heat exchangers.
BACKGROUND OF THE INVENTION
Heat Exchangers are used in the chemical and separation processes for heat transfer to cool or heat the process streams.
Traditional shell and tube heat exchanger generally comprises two parts namely shell and tubes. The tubes are welded between the plates and baffles are welded or mechanically fitted between the plates before the welding the tubes and spacers may be introduced between the baffles over the tubes. The welded part is then mechanically fitted in the shell. Hence manufacturing cost of the shell and tube heat exchanger is expensive and comprises number of steps. However, the thermal capacity of the heat exchanger is limited as well as comprises limitation of pressure as high pressure service involves capability to sustain the fluid pressure and thereby involves relatively heavy structures associated with the heat transfer equipment. Apart from the heavy walls that are required for individual heat transfer fluid passages, high pressure requirements make manifold requirements severe. Additionally, it is difficult for high pressure heat exchange units to attain high reliability in that each joint associated with the heat exchanger unit exposed to high pressure service is a possible source of leakage. Further, it is difficult to fabricate heat exchangers of large size due to size limitations on parts imposed by the fabrication equipment.

The existing heat exchangers with manifold requirements reduce heat transfer efficiency as fluid circulation is poor due to these manifolds that connect ports at ends. Further, it is costly to manufacture and/or assemble such heat exchangers.
US4852233 and US572995 claims different typed of extruded flat multi port tube heat exchanger made of aluminium where tube is folded into parallel loops forming a rectangular heat exchanger "stack with an inlet at one and outlet at other end. However, the heat transfer efficiency is reduced to poor fluid circulation and pressure drop is more.
It is therefore, a need in the art for heat exchanger that overcomes the shortcoming associated with existing systems.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides an extruded heat exchanger. The heat exchanger comprises a shell, a plurality of tubes and end plates arranged to form a flow path for a fluid in the tubes wherein the tubes are connected longitudinally in a manner that at least one connecting element between the tubes acts as longitudinal baffles defining a predetermined counter and/or cross flow path of a fluid in the shell across the tubes.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings that will now be briefly described are incorporated herein to illustrate an embodiment of the invention.
FIG. 1 is a perspective view of a heat exchanger in accordance with an embodiment of the present invention.

FIG. 2 shows internal structure of a tube of the heat exchanger in accordance with an embodiment of the present invention.
FIG. 3 shows the heat exchanger with directional flow of refrigerant and water in accordance with an embodiment of the present invention.
BRIEF DESCRIPTION OF THE INVENTION
Various embodiments of the present invention provide an extruded heat exchanger. According to an embodiment the present invention provides an extruded heat exchanger comprising a shell, a plurality of tubes and end plates for defining the flow path of a fluid in the tubes wherein the tubes in a line are connected longitudinally in a manner that at least one connecting element each between the tubes acts as longitudinal baffles defining a predetermined counter and/or cross flow path of a fluid in the shell across the tubes.
According to an embodiment of the present invention, the tubes in a line are extruded along with the connecting element as per the predetermined design of the heat exchanger. Alternatively, the present invention, the connecting element can be welded to the tubes in a line as per the predetermined design of the heat exchanger.
According to an embodiment of the present invention, the shell and the tube bundle of the plurality of the tubes along with the connecting elements can be extruded together.

According to an alternative embodiment, the plurality of tubes or a bundle of with the longitudinal connections can be extruded separately and mechanically flitted to the shell.
According to the present invention, atleast the plurality of tubes with connections is extruded from aluminium or aluminium alloys or can be made of known metals, alloys or combination thereof joined longitudinally together by known means including welding, brazing etc.
According to the preferable embodiment of the invention, the heat exchanger is made of metal, metal alloys including aluminium, aluminium alloys and combinations thereof.
According to an embodiment of the invention, the tubes may comprise of internal and/or external fins to increase surface area of the tubes.
According to the present invention, the heat exchanger can be extruded ranging from zero to available maximum extrusion length as possible.
According to the present invention, the shell can be of any cross section shape including circular, square, triangular, rectangular, polygonal etc.
Referring to Fig. 1, the present invention provides an extruded heat exchanger 100 comprising a plurality of tubes 10 which are extruded with internal serrations 15 for increasing refrigerant/gas side area, a plurality of connecting elements 20 for directing water flow and refrigerant flow in the heat exchanger.

In an embodiment, the connecting elements 20 are baffles 20.
As per one embodiment of the present invention, refrigerant flows through internal surface of the tubes 10 having internal serrations for increasing the surface area as shown in Fig. 2 and Fig.3.
As per an embodiment the present invention provides internal serrations to increase tube side area by more than 4.5 times the shell side area.
In an embodiment, the shell side fluid flows radially from right to left across connecting element that is baffle 20 and tube side fluid flows through tubes 10 from left to right as shown in Fig. 3 thereby provides a cross flow. The counter and/or cross flow of the fluids provide maximum efficiency and less water side pressure drop.
As per an embodiment, the length of internal serration/extrusion of the tube from inside surface may be modified to increase the heat transfer. Further, the number of tubes 10 may also be varied as per requirement for improving heat transfer efficiency. The flexibility with these parameters provides a customized arrangement without incurring major additional cost.
The heat exchanger of the present invention has maximum efficiency, less shell side pressure drop, less material & process cost. Further capacity of the hat exchanger can be easily changed along with circuit at low cost. Moreover the heat exchangers can be easily cleaned. As the heat exchangers of the present invention can be extruded, the cost of manufacturing is less.

The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since, modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the disclosure and the appended claims.

WE CLAIM
1. An extruded heat exchanger comprising:
a shell,
a plurality of tubes and end plates arranged to form a flow path for a fluid in the tubes wherein the tubes are connected longitudinally in a manner that at least one connecting element each between the tubes acts as longitudinal baffles defining a predetermined counter and/or cross flow path of a fluid in the shell across the tubes.
2. The extruded heat exchanger as claimed in claim 1 wherein, the tubes are extruded along with the connecting element as per the predetermined design of the heat exchanger.
3. The extruded heat exchanger as claimed in claim 1 wherein, the connecting element is welded to the tubes as per the predetermined design of the heat exchanger.
4. The extruded heat exchanger as claimed in claim 1 wherein, the shell and a tube bundle of the plurality of the tubes along with the connecting elements is extruded together.
5. The extruded heat exchanger as claimed in claim 1 wherein, the plurality of tubes or a bundle of with the longitudinal connections is extruded separately and mechanically flitted to the shell.

6. The extruded heat exchanger as claimed in claim 1 wherein, the heat exchanger is made of metal, metal alloys including aluminum, aluminum alloys and combinations thereof.
7. The extruded heat exchanger as claimed in claim 1 wherein, the tubes includes internal and/or external fins to increase surface area of the tubes.
8. The extruded heat exchanger as claimed in claim 1 wherein, the heat exchanger can be extruded ranging from zero to available maximum extrusion length as possible.
9. The extruded heat exchanger as claimed in claim 1 wherein, the shell is of any cross section shape including circular, square, triangular, rectangular, polygonal etc.
10. The extruded heat exchanger as claimed in claim 1 wherein, internal serrations to increase tube side area by more than 4.5 times the shell side area.