A NEW HEAT EXCHANGER AND MANUFACTURING METHOD

TECHNICAL FIELD

This invention is related with a new and low cost manufacturing process to be used for manufacturing the refrigeration circuit heat exchangers, like condensers and evaporators.

Said invention is especially related with the heat exchangers made with aluminum MPE profiles and aluminum fins combination. Because there is no need for the said MPE profiles or fins to have any brazing alloy clad on the surface, there is no need to use any flux, and there is no need to use any high temperature control atmosphere; the invented low cost manufacturing process reduce the heat exchangers' costs dramatically. PREVIOUS TECHNIQUE

Because the energy is getting more and more valuable in the world, numerous amount of researches are going on in order to reduce the energy consumption in the systems running continuously especially, like in the ones in the refrigeration field. Hence, numerous researches are carried on in order to reduce the energy consumptions helping also the refrigeration industry to be developed. The heat exchangers like condensers and evaporators are among the primary refrigeration components affecting the end product's efficiency and cost. Heat exchangers are the components creating heat exchange in between two more fluids having different temperatures. In such components the fluids are separated from each other by means of the surfaces (tubes, profiles) providing the heat exchange. Heat exchangers are commonly used in most of industrial applications like refrigeration, heating and ventilating, power plants, chemical plants, and automotive. The radiators in water cooled engines; condensers and evaporators in refrigeration, air conditioning, thermal power, and chemical plants are common examples.

In most of current heat exchanger applications a large variety of tubes or profiles are used, and in order to increase the heat transfer surface, low thickness fins are added to tubes or profiles. Tubes could be made out of steel, copper, or aluminum. The material for the fins is aluminum in general, but steel or copper could also be used depending on the application. Such heat exchangers are relatively high in cost due to heavy material used and also due to current techniques being applied to make the fin combination.

In the application, there also exist heat exchangers made with relatively light weight aluminum MPE (multi port extrusion) profiles which are combined with aluminum fins. Such heat exchangers (condensers and evaporators) could generally be classified in 2 types. In one of the types known as "parallel flow" heat exchangers, the aluminum MPE profile is cut to single lengths, the cut lengths are placed in between 2 tubes (headers) by inserting the open ends into the headers, the preformed zigzag shaped aluminum fins are placed in between the MPE profiles. In the other type, commonly named as "continuous flow", a certain length MPE profile is formed to serpentine shape with one inlet and outlet and again the preformed zigzag shaped fins are placed in between the passes of the serpentine. In both of the types, the said prepared assemblies have to pass through a furnace having control atmosphere inside in order the fins to be brazed firm to the MPE profiles, and the profiles to the headers as leak proof. In order the brazing operation to be made properly, either MPE profile, or fins, or both of them, have a brazing alloy clad on the surface; and also the flux has to be applied to the assemblies (spray or bath) before they enter into the brazing furnace in order to avoid any negative effect of oxides and dirts on the surface. No matter how economical is the MPE profile by itself due to the lower unit weight, the involvements of the cladding and the flux make the application expensive due to both cladding and flux are supplied by a few companies only. Also the high temperature (750°C) control atmosphere furnace operation and cleaning operation of the flux residue after the furnace, and the high investment cost of the furnace are the other factors that result the MPE heat exchangers to be expensive.

Despite how expensive are the MPE heat exchangers made by the current technique, they are more efficient and find application in areas where really high efficiency is needed like air conditioning, or like automotive air conditioning where high efficiency is needed in a limited space. But they have never found application in domestic refrigerators or commercial coolers for example, due to their high costs.

The heat exchangers (condensers and evaporators) used in the domestic refrigerators and commercial coolers today, are all made of steel, aluminum, or copper tubes in general. Below are some examples of such condensers and evaporators:

One of such known as "no frost evaporator" is an aluminum tube serpentine as inserted into a pack of numerous aluminum fins which could be at different spacing (no brazing and relatively loose tube to fin contact).

Another such is "POT (plate on tube) evaporator" which consists of an aluminum tube serpentine attached to a thin aluminum plate either mechanically (rivets, clamps), or by means of a gluing film (gel) under heat and pressure.

Another such is "WOT (wire on tube) evaporators" where individual shelves made with resistance welding of steel tube serpentines and steel wires are brought together in series as one over the other (2-8 shelves) to form a continuous flow heat exchanger. Another such is "WOT (wire on tube) condensers" which could be a single layer steel tube serpentine and steel wires (welded) combination (static condenser), or similarly made single layer having relatively narrow width and longer length and bent over itself (to either zigzag or helical shape) to form a compact condenser (dynamic condenser).

Another such is the "copper tube + aluminum fins" heat exchangers used in commercial air conditioning systems and in condensing type domestic cloth drier machines. Where certain amount of preformed copper tube hairpins are inserted into a pack of aluminum fins (manual), inner diameter of hairpins are enlarged from the inside (special pres) to get a tight tube to fins contact, copper return bends are placed and brazed to the open ends of hairpins to get a continuous flow inside of the heat exchanger. Such high efficient heat exchangers are high in cost, but find application in the a.m. areas.

In current application, apart from the ones explained above, there are also heat exchangers made with the "aluminum MPE Profile + aluminum fins" combination. Such heat exchangers could either be "parallel flow" type, or "continuous flow" type as explained above. Our invention is a new and highly cost effective method to manufacture such "continuous flow" type heat exchangers as compared to the current/traditional method for the same. In order to better understand the difference, the current/traditional method has to be understood first, as below:

In the current/traditional technique, the aluminum MPE profile, or the fin stock, or both, have to contain a brazing clad on the surface. Such raw materials having the clad on the surface are in the hands of a few companies and hence the prices are rather high.

In the current/traditional technique, the aluminum MPE profile serpentine and the zigzag formed fins are placed inside a fixture and the fixture is fed into the brazing furnace having control atmosphere inside. Before entering to the furnace, all of the assembly is sprayed by flux or dip into a flux bath. As the fixture progresses inside the furnace, the flux liquidities at around 500°C and wets all of the areas to be brazed together. This is needed for cleaning the areas to be joined out of dirt's or oxides in order to have proper conditions for good brazing in the next step ahead. Then, at around 750°C, the clad on the fins (or on the profile) is smelted down and brazes the parts in contact with each other. The already brazed assembly is cooled down inside the furnace (still under control atmosphere) and then goes out of the furnace. At the exit, the brazed assembly (heat exchanger) inside the fixture is taken away and the flux residue on the surface is cleaned by means of a separate operation. The above explained current/traditional technique or method is incomparably more expensive as compared to the invented new method due to: • The clad layer on the raw material of aluminum MPE profile or fin stock (the same raw materials are used at our invention but no clad layer is needed. Instead of the high cost clad, commonly found and low cost gluing film is used only)

• The rather long, high temperature furnace which also has control atmosphere is a very expensive investment (whereas in our invention a very small low temperature, very low cost oven having no control atmosphere is needed only).

• The flux which has to be used is expensive (whereas no flux is needed in our invention)

• The high brazing temperature (750°C), the long brazing time (40-50 minutes), and the control atmosphere involvement make the operation cost very high due to the high energy consumption (whereas in our invention, the gluing takes place at 230°C and in 30 seconds only without requiring any control atmosphere)

• The fixtures have to be made out of stainless steel due to the high working temperature of 750°C and the corrosive atmosphere in the furnace (whereas in our invention ordinary steel fixtures could be used due to the low working temperature like 230°C).

The above explanations show how cost affective is our invention as compared to the current/traditional method. Naturally, our invention will open the doors for the MPE heat exchangers (condensers and evaporators) into the refrigeration industry as the first time in the history. Apart from the above cost comparison made with respect to the current/traditional method, the MPE heat exchangers will also have the following advantages against the currently used heat exchangers (condensers and evaporators) in the refrigeration industry today:

• The current heat exchangers are all made of tubes with the combination of different fins and are relatively bulky due to lower efficiencies they have. The alternatives made with the MPE profiles via our invention will be more compact to create more space in final products for end users, and also to give flexibility for designers.

• In the current NF (no-frost) evaporators, defrosting is a problem and relatively high power resistance heaters are used to ensure the defrosting. Whereas the MPE alternatives made with our invention will have the slippery gluing film layer on the fins to enable easier defrosting and hence to use lower power heating elements (energy saving).

• In the current (forced circulation) compact condensers made with steel tube and steel wires combination, the dust accumulated on the surface in time is a problem as the efficiency drops down accordingly and power consumption of the end product increases. Whereas the MPE alternatives made via our invention will have the slippery gluing film layer on the fins to enable less dust accumulation and hence to save in the energy consumption of the end product.

• ^' In most of the current heat exchangers (condensers and evaporators) being used today, the corrosion due to the different metals used in the same component, galvanic corrosion (battery affect) takes place in time and the components need to be protected by additional means to avoid the problem. Whereas the MPE heat exchangers made via our invention will be all-aluminum and will not have any corrosion concern at all.

• The currently used cooling circuits are not so good for recycling due to the different metals have to be used (steel condensers, copper capillary tubes and connectors, plastic protective sleeves, etc.). Whereas the MPE heat exchangers (condensers and evaporators) made via our invention, will open the door of all-aluminum cooling circuit with no recycling or environmental concern at all. As a result, it is apparent that the MPE heat exchangers made via our invention:

1. Will be much less expensive as compared to the same heat exchangers made with the current traditional method.

2. Will open doors of using MPE profiles for the refrigeration and commercial coolers industry.

3. Will provide cost and energy saving advantages for the refrigeration and commercial coolers industry with respect to the currently used heat exchangers.

4. Will create values for the environment due to opening doors for all-aluminum cooling circuits. THE AIMS OF THE INVENTION

The invented method, as explained above, is a means of solving many current problems in the refrigeration and commercial coolers' industries at the same time as it will open doors of using aluminum MPE profile heat exchangers in the said industries. The invention in general, is a new method of combining the aluminum MPE profiles with aluminum fins by means of a gluing film only, by avoiding many current/traditional manufacturing steps like clad on the said raw materials, flux, any furnace control atmosphere brazing operation, and cleaning.

The main aim of the invention is to develop and manufacture cooing circuit heat exchangers (condensers and evaporators) by using the aluminum MPE profiles for the refrigeration and commercial coolers' industries mainly, as such heat exchangers will be much less expensive as compared to the traditionally made MPE heat exchangers and also they will bring many other advantages (below) with respect to currently used tubular heat exchangers. The invention will open doors of using MPE profiles in the said industries for the first time in history. Another aim is to bring considerable cost savings for the refrigeration and commercial coolers' industries due to lower cost of the MPE heat exchangers made via the invented method and also due to the higher efficiencies of such heat exchangers as compared to the currently used (tubular) ones. Another aim is to develop more compact heat exchangers to provide more space in the final products for end users and to bring flexibility to the designers.

Another aim is to decrease the energy consumptions of final products (refrigerators and coolers) as a result of more efficient MPE heat exchangers (condensers and evaporators).

Another aim is to decrease the defrost heater powers due to the MPE no frost evaporators will have slippery aluminum fins due to the gluing film on the surface and hence the ice formation on the fins will be easier to remove (saving in defrosting energy). Another aim is to prevent excess energy consumption due to dust accumulation in current (steel) condensers, by replacing them by MPE condensers having slippery fin surfaces due to the gluing film layer on the surface to avoid or decrease the dust accumulation.

Another aim is to replace current heat exchangers also in other industries to the extent possible with the MPE heat exchangers due to the flexibility of our invention and the lower cost of MPE heat exchangers made via the invention.

Another aim is to avoid the expensive clad layer on the MPE profile (or fin stock) and to replace it with much less expensive gluing film available in the market (cost saving for MPE heat exchangers and the producers).

Another aim is to get rid of expensive flux application in the case of the current/traditional method of MPE heat exchanger production (there is no flux in the invented method). Another aim is to get rid of very high investments needed in the current/traditional production method of the MPE heat exchangers (no high cost control atmosphere industrial furnace is needed). Another aim is to get rid of the expensive stainless fixtures which have to be used in the current/traditional MPE heat exchanger production (in our invention ordinary steel fixtures could be used).

Another aim is to manufacture the MPE profile heat exchangers at 230°C in open atmosphere directly, instead of elevated temperatures like 750°C and control atmosphere involvement like in the case of current/traditional method of MPE heat exchangers production method.

Another aim is to perform the aluminum MPE profile to aluminum fin connections in a couple of minutes in open air at 230°C and, instead of 40-50 minutes at 750°C under control atmosphere like in the case of current/traditional method of MPE heat exchangers production method (much less energy per heat exchanger).

Another aim is to be able to make capacity increase investments when needed within a few months, instead of waiting for 8-10 months like in case of the current/traditional method of MPE heat exchangers production (low cost and easy to make investment). The new invented method will facilitate to produce the MPE heat exchangers satisfying all of the aims listed above. Said heat exchangers will lower the costs and also will lower the energy consumptions in the refrigerators and commercial coolers and hence will find a large application in the said marketplace. Said MPE heat exchangers are a combination of aluminum MPE profiles and aluminum fins and the firm contacts in between the profiles and the fins are performed by the gluing film pre applied on the fin surface. The said firm contacts in between the profiles and fins could also be performed by the pre applied gluing film on the surface of the MPE profiles as well.

The manufacturing steps of the invented method as follows:

• Applying gluing film on the aluminum fin stock (automatic).

• Slitting the glue applied fin stock into the widths needed and to perform the zigzag shaped fins at the lengths needed.

• Cutting the MPE profile (having no clad on the surface) to lengths and forming them to serpentine shape.

• Manual placing of the zigzag fins and the serpentine into the fixture and fixing the fixture to secure the parts inside to get in touch with each other. • Replacing the fixtures on the conveyor to feed them into the oven kept at 230°C having no control atmosphere inside.

• Securing the fixtures to stay at 230°C for 30 seconds at least.

• Cooling down the fixtures to room temperature after the oven/heat treatment.

· Taking the MPE heat exchanger out of the fixtures.

Said invented method as described above will produce the most economical and most efficient MPE heat exchangers (condensers and evaporators) for the refrigerators and commercial coolers and will be highly accepted and broadly applied by the respective manufacturers.

REFERANCE NUMBERS 1. Aluminum MPE Profile

2. Zigzag shaped aluminum Fin

3. Fixtures

4. Oven having no control atmosphere

5. Heat Exchanger

DETAIL A: cut section of a MPE Profile or Multi Port Profile

DETAIL B: cut section of MPE profile as combined with zigzag fins

EXPLANATIONS OF FIGURES FOR BETTER UNDERSTANDING OF INVENTION Figure-1: shows the cut section of a typical aluminum MPE profile, and the front and side views of a typical serpentine made out of MPE profile.

Figure -2: shows the front and side views of typical fins formed in zigzag shape (fins have the gluing film layer on both of the sides).

Figure -3: shows the front, the side, and the enlarged "detail B" views of a typical MPE profile serpentine and the typical zigzag shaped fins as brought together.

Figure-4: shows a typical MPE profile serpentine + zigzag shaped fins assembly as fixed firm inside the respective fixture.

Figure-5: shows a typical fixture containing the MPE profile serpentine + zigzag shaped fins firmly fixed inside and as entered inside an oven. Figure-6; shows a typical MPE Heat exchanger as taken out of the fixture after it was cooled down to room temperature inside the fixture.

The description of the invented method, the characteristics, and the advantages with respect to the current/traditional method of producing MPE heat exchangers will be better understood after a close examination of the detailed explanations below. Hence the final conclusion should be made by taking into account the same explanations below.

DETAILED EXPLANATION OF THE INVENTED METHOD

The figures above are given for the better understanding of the invented method. The MPE profile (1) or the zigzag shaped fins (2) could naturally be extruded or formed respectively in different geometries or in different dimensions.

The MPE heat exchanger described here (5), consists of a aluminum MPE profile (1) and the zigzag shaped fins having the gluing film already applied at the surface on both sides (2). The first step of the invented method is to apply/coat the gluing film on both side of the fin stock out of which the typical zigzag shaped fins (2) to be slit and formed. The said gluing film could also be applied/coated on the MPE profile (1) as well. This is an alternative for the said first step which must be considered inside of our invented method. Then the aluminum MPE profile which has no clad on the surface and which is supplied in rolls is de-coiled and cut to certain lengths and the lengths are formed to the serpentine shape (1). Then the said MPE serpentine (1) and the zigzag shaped fins (2) are brought together inside a fixture (3) to be kept together firmly. Then the fixture (3) which contains the assembly secured firmly inside;

· Is inserted (fed) into an oven having no control atmosphere inside and kept at 230°C (4) and is passed through the oven.

• It must be secured that the assembly inside the fixture (3) must be heated up to 230°C all around and kept at that temperature for at least 30 seconds while the fixture (3) + the assembly are still inside the oven (4).

· It must be secured that the fixture (3) containing the assembly inside must be left to be cooled down to the room temperature (4),

After the MPE serpentine + fins assembly secured in the fixture (3) is kept at 230°C inside the oven (4) for 30 seconds, the gluing film on the zigzag shaped fins' surface gets smelted down and connects the aluminum fins firmly with the aluminum MPE profile forming the aimed MPE heat exchanger. After the fixture (3) is taken out of the oven and is cooled down to room temperature, the formed MPE heat exchanger (5) inside the fixture (3) is taken away as ready to be used (no cleaning is needed). Figure 6 shows a typical MPE Heat Exchanger. The invented method is still valid whether the said gluing film is coated on the aluminum MPE profile alone (1), on the aluminum fins (2) alone, or on both of them together.

The concept of the protection of this invention could not be limited with the samples or examples described above. Anybody having descent technical/engineering manners could develop similar methods by looking at this innovation, and also could develop similar products at different areas. Therefore, it is obvious that so developed methods or products must be considered within the concept of this invention, and must be taken as violating the rights of this invention.