The present invention refers to heat exchanger elements. Furthermore, the invention discloses a method for the production of heat exchanger elements. Finally, the invention refers to a heat exchanger including inventive heat exchanger elements.

It is state of the art to use different kinds of heat exchangers for different purposes. Usually, heat exchangers are used to recover heat energy from one fluid or medium into another one. This kind of heat energy is called sensible energy. The heat energy or sensible energy of one fluid, normally air, is recovered into another one which is running adjacent, e.g. parallel, counter or cross flow, to the first where the fluid is at lower temperature. By inversing fluid flows, the exchange between the two will generate a cooler fluid. Heat exchangers used for sensible energy recovery are usually made of metal or plastic plates. There are different types as there can be cross flow, parallel flow or counter flow configurations. The plates are defining flow channels between themselves so that the fluids can flow between the plates. Such devices are e. g. used in residential and commercial ventilation (HRV).

Another type of energy exchangers refers to the so called latent energy which is the moisture. To exchange the latent energy it is known to use desiccant coated metal or plastic substrates or membranes made from desiccant impregnated cellulose or polymer. Between plates made from cellulose or polymer, air passages are defined or created to allow the fluids to pass along the surface of the plates, thereby transferring moisture from one fluid to the other one. As the membranes usually have no structural strength, it is known to combine the membranes with frames or grids which thereby define spacings between the membranes.

In case of a combination of the above, the energy exchangers are called Enthalpy exchanger. Those Enthalpy exchangers allow for the exchange of sensible and latent energy, resulting in Total Energy recovery.

Membrane materials as currently available are delivered by the roll. The membrane material is the most critical part of an Enthalpy exchanger. The membrane must be fixed and sealed to a kind of grid or frame and arranged in a way to allow for a fluid to flow between each membrane layer. So, it is obvious that Enthalpy exchangers of the known art are a compromise. They will usually lose in sensible energy to gain in latent energy as a result of the selective scope and characteristics of currently used membranes.

Such a heat exchanger built from respective elements is e. g. WO 02/072242 A1. On grids respective membranes made of fibres are positioned. The grids are stapled thereby altering the direction of the plates in order to create different air flow directions.

In view of the mentioned state of the art it is an object of the invention to provide heat exchanger elements and heat exchangers as well as a method for the production of heat exchanger elements. The inventive heat exchanger elements allows for the creation of Enthalpy exchangers whereby the efficiency of sensible energy exchange and latent energy exchange can be varied and controlled and especially improved.

With the invention, the solution of the above mentioned object is presented by a method for the production of heat exchanger elements according to claim 1. With regard to the heat exchanger element, the object is solved by an element with the features of claim 11. A heat exchanger is claimed in claim 18. Improvements and further features are disclosed in the subclaims.

According to the invention, a new hybrid exchanger element is provided which on one hand has enough structural strength and density to create air flow channels for any type of cross flow and/or counter flow energy exchanger, thereby allowing for the use of a structurally strong material which is good for sensible energy exchange, on the other hand by size and number of perforations or openings or holes it is possible to define an area which is filled with a polymer solution with latent energy exchange characteristics. It is obvious that the efficiency of sensible energy exchange on one hand and latent energy exchange on the other hand can be defined, controlled and adapted to the respective needs of the environment (dry air, humidity, outside temperature and the like).

According to the invention, a plate element can be made of aluminium or plastic or combinations thereof. The element can be provided with corrugations. Corrugations can be designed to optimize the efficiency to pressure drop ratio. The corrugations can be chosen to allow for creating flow channels between similar plates when those are stacked together. By the definition of the corrugation, one advantage will be the enhancement of the surface which is available for energy transfer. This can be built up as large as possible and can even reach an increase of 100% and more. Furthermore, the corrugations can be designed in a way to allow for the easy arrangement of counter flow or cross flow configurations, e. g. by choosing oriented corrugations and alternating the position of the plate.

The border of the plate defines an area where similar plates can be fixed together in an appropriate way. This can be welding, e. g. laser welding, ultra sound welding and/or folding, crimping and the like. This stabilizes the rigidity of the package as well as allows to build up the desired flow channels. The border area can be flattened, tongue/groove system, profiled or rimmed to allow for a tight sealable connection between plates.

The perforations can be performed at the time of the plate production e. g. integrally when the plate is molded or stamped or embossed or vacuum formed.

The polymer can be one according to the state of the art, e. g. like the product "Aquivion", a trademark of Solvay or "Nexar", a trademark of Kraton.

The material can be e. g. a ionomer in form of a copolymer produced from tetrafluoroethylene, C ₂ F ₄ , and Ethanesulfonyl fluoride, 1,1 ,2,2-tetrafluoro-2- [(trifluoroethenyl)-oxy], C ₂ F3-0-{CF2)2-S0 ₂ F, sulfonated block copolymer.

However, the polymers can be adapted to the desired characteristic and features.

According to the inventions, the polymer is supplied as a dispersion. The dispersion can be brought to the plate by thereby filling or covering the holes or perforations with the polymer solution by way of spray, dipping, serigraphy or any other lamination method. It is obvious that the amount or efficiency of latent energy recovery depends on the surface provided by the holes or perforations, their shapes and their locations. So it is possible to adapt the heat exchanger plates to the environmental and functional conditions.

By using the highly heat conductive materials as the structural elements for the Enthalpy membrane, high sensible efficiency is ensured. By defining the perforations and choosing the polymer, high latent recovery is ensured.

The corrugation/embossing of the plate increases the exchange surface significantly.

The perforated or opened portions of each plate can reach 70% or more, of the total surface area e.g mosquito screen pattern. In such a case, the surface exceeds that of a flat membrane according to the state of the art), with minimal loss of the high sensible energy recovery characteristic of the exchanger plates. A Total Energy recovery efficiency of up to 85% can be reached in heating mode and 72% in cooling mode. A number of finalized plates can be stacked together to build a package which, within a frame or housing, creates a heat exchanger according to the invention.

Combined sensible and latent energy to such a high Total Energy recovery level could, in some climatic zones, eliminate the need for a sensible only heat exchanger .

The polymer can be combined with additives to manifold and magnify its attributes. It can be, for instance, efficiently anti-bacterial and can meet fire resistance requirements (UL). Its viscosity can be adjusted to achieve the optimal tunable exchange features of the plate allowing as high a moisture exchange as possible.

It is obvious that the sensible energy transfer and the latent energy transfer capabilities of the heat exchanger are tunable and adjustable. The plates are adaptable to environmental conditions by the variable mosaic geometry of the perforations. E. g. an exchanger can be designed to operate at temperature under the freezing point {- 10° C) without ice built up only by choosing the right position of the perforations and polymeric treatment of the constitutive plates.

The rigidity of the structural elements could make the plate and thereby the membrane capable of handling pressure differential up to 1 Kpa. within the exchanger. This advantage opens the door to larger exchanger constructions for commercial applications.

The invention provides a simple method for the production of energy exchanger plates allowing sensible as well as latent energy exchange. The design and the adaptability of the plates allows for the construction and design of heat exchangers which are optimized with regard to the technical requirements and/or the environmental conditions.

Stamped, corrugated, embossed or vacuum formed aluminium, stainless steel, resin based plates and/or plastic plates can be made using proven automation technologies including the assembly, e. g. by vacuum grip, and seal, e. g. by laser welding, ultra sound welding, folding, crimping, to obtain packages of superposed rigid plates. The plates are washable, fire resistant, antibacterial, sealed e.g. leakage proof. They have all valuable advantages that are necessary to create highly efficient heat exchangers.

The selective perforation of the plates and the air-tight casting of the mosaic polymer micro membranes allows for the construction of structural hybrid mosaic membranes. The plate perforation, too, can be performed by pre-programmed continuous laser processes, by mechanical systems like needle-roller and the like, or chemical etching processes.

Further features and aspects of the invention become obvious from the following description of the drawings. The drawings show:

Fig. 1 a top view of one example for an embodiment of an exchanger plate according to the invention and

Fig. 2 a side view of the plate according to figure 1.

In the drawings, the same elements are designated by the same reference numbers.

An exchanger plate 1 consists of a structural rigid plate 2 made from aluminium, plastic or the like. Plate 2 has a rim 4 which is a flat sealable rim and can be deformed for sealing. Areas of the rim 4 are opened or deviated as shown by reference no. 5 to define e. g. a inlet and outlet of a flow channel. Within the rim area, corrugations 3 are stamped or embossed into the plate 2. When similar plates are sealed together, flow channels are defined. In the example, reference no. 6 designates areas with perforations.

For the purpose of clarity, only some of the perforation areas 6 and some of the corrugated areas 3 are designated.

The heat exchanger element 1 shows a great surface for heat exchange which is increased by the corrugations 3 which are corrugated in one direction only and open on the other surface. Furthermore, the perforated areas 6 define a latent energy exchange area for the transfer of moisture.

These plates will be stacked to build a heat exchanger e. g. for ventilation systems to exchange heat from outgoing to incoming air (or vice versa for free cooling in summer) as well as humidity from outgoing to incoming air in winter (or vice versa for moisture reduction in summer or all year round in hot and humid climatic zones).

The drawings and the description do in no way restrict the invention and are meant for describing an example, only.

Reference numerals:

1 heat exchanger element

2 plate

3 corrugation

4 border

5 opened border

6 perforations