Method of manufacturing a heat-humidity exchange plate of an enthalpy air-to-air exchanger

Abstract

A heat and humidity exchange plate for an air-to-air heat exchanger is made by continuously forming an expanded metal structure from a strip of metal foil by slitting the metal foil in a transverse direction, stretching the metal foil in a longitudinal direction, and then rolling over an entire width of the strip of metal foil. The expanded metal structure is subjected to an annealing heat treatment. A vapour-permeable polymeric membrane is provided on the annealed expanded metal structure. Corrugated and embossed-shaped elements are formed on the annealed expanded metal structure with the vapour-permeable polymeric membrane by means of omnidirectional deformation. A circumferential shape of the exchange plate is formed by removing excess edges from the annealed expanded metal structure with the vapour-permeable polymeric membrane.

Claims

1. A method of manufacturing a heat and humidity exchange plate for an air-to-air counterflow enthalpy heat exchanger, the method comprising the following steps: (a) continuously forming a supporting member of the exchange plate in a form of an expanded metal structure from a strip of metal foil by sitting the metal foil in a transverse direction, then stretching the metal foil in a longitudinal direction, and then rolling over an entire width of the strip of stretched metal foil; (b) annealing the expanded metal structure; (c) providing a vapour-permeable polymeric membrane on the annealed expanded metal structure; (d) forming corrugated and embossed shaped elements on the annealed expanded metal structure with the vapour-permeable polymeric membrane applied thereon by means of omnidirectional deformation; and (e) creating a circumferential shape of the exchange plate by removing excess edges from the annealed expanded metal structure with the vapour-permeable polymeric membranes.

2. The method according to claim 1, wherein an amount of elongation of the strip of metal foil from the stretching in the longitudinal direction is in a range of 20% to 70%.

3. The method according to claim 1, wherein steps (d) and (e) are performed in a single process step.

4. The method according to claim 1, wherein the expanded metal structure is formed from aluminum or an aluminum alloy.

5. The method according to claim 1, wherein the annealing is carried out continuously.

6. The method according to claim 1, wherein the annealing is carried out after winding the expanded metal structure onto winding coils, wherein the winding coils are then inserted into an annealing furnace.

7. The method according to claim 1, wherein after the annealing, the expanded metal structure is provided with the vapour-permeable polymeric membrane by applying a liquid polymer to the expanded metal structure which, when cured, forms the vapour-permeable polymeric membrane.

8. The method according to claim 1, wherein after the annealing, the expanded metal structure is provided with the vapour-permeable polymeric membrane by attaching a strip of the vapour-permeable polymeric membrane to the expanded metal structure.

9. The method according to claim 8, wherein before attaching the strip of the vapour-permeable polymeric membrane, a surface of the expanded metal structure or a surface of the vapour-permeable polymeric membrane is activated chemically or by plasma treatment.

10. The method according to claim 8, wherein the strip of the vapour-permeable polymeric membrane is attached over an entire width of the expanded metal structure.

11. The method according to claim 8, wherein the strip of the vapour-permeable polymeric membrane is attached to the expanded metal structure by gluing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be described with reference to the drawings, wherein

(2) FIG. 1 represents a diagram of a counterflow enthalpy heat exchanger,

(3) FIG. 2 shows a heat and humidity exchange plate of the heat exchanger,

(4) FIG. 3 shows a diagram of creating an expanded metal structure,

(5) FIG. 4 shows a diagram of the connection of the expanded metal structure to a vapour-permeable polymeric membrane,

(6) FIG. 5 is a view of the starting metal foil with a part slit and stretched,

(7) FIG. 6 is a view of a part of the expanded metal structure after rolling,

(8) FIG. 7a is a front view of a semi-finished product for the production of the heat and humidity exchange plates,

(9) FIG. 7b is an axonometric view of the semi-finished product for the production of the heat and humidity exchange plates,

(10) FIG. 7c is a side view of the semi-finished product for the production of the heat and humidity exchange plates,

(11) FIGS. 8a, 8b show the formation of the heat and humidity exchange plate, and

(12) FIG. 9 shows a view of a double hem of a plate joint.

DETAILED DESCRIPTION

(13) In the following description of the alternative exemplary embodiments represented in the figures, the same reference signs are utilized for features that are identical or at least comparable in terms of their configuration and/or mode of operation. Provided the features are not described in detail again, their design and/or mode of operation correspond/corresponds to the design and mode of operation of the above-described features. For the sake of greater clarity, reference signs for previously described components have not been individually included in the figures.

(14) An air-to-air counterflow enthalpy heat exchanger is a device used to transfer heat and moisture from the air coming out of the indoor service space to the air entering from the outdoor space into the indoor space.

(15) The basic building block of a counterflow enthalpy heat exchanger 1 are heat and humidity exchange plates 10, which are arranged in parallel one above the other and are connected to each other on parts of their circumferences. Thus, alternating flow-through inter-plate spaces are formed between the pairs of heat and humidity exchange plates 10, forming air channels 2 for air flow in direction A from the enclosed indoor space to the outdoor space and air channels 3 for air flow in direction B from the outdoor space to the enclosed indoor space. The heat and humidity exchange plates 10 allow heat and humidity transfer from the heated and humid air discharged from the ventilated space to the cold drier air supplied from the outdoor space inwards. The heat and humidity exchange plate 10 is formed by a moulded piece which is shaped on both sides into a corrugated and embossed surface creating protrusions and depressions to generate turbulent flow. It follows from the above that each of the inner plates 10 lies between the air channels 2, 3 in which air flows in the opposite direction. The connection of the heat and humidity exchange plates 10 is made at the edges by pressing with a double hem 11 of the joint, thereby preventing air leakage from the space between the plates 10 in the respective air channel 2, 3.

(16) The heat and humidity exchange plate 10 assembly is inserted and fixed in the housing 4 of the counterflow enthalpy heat exchanger 1.

(17) The heat and humidity exchange plate 10 comprises a supporting member 101, whose at least one side is covered with a vapour-permeable polymeric membrane 102. The supporting member 101 is formed by an expanded metal structure 1010. The central portion 12 of the plate 10 has a shape of a rectangular quadrilateral, at whose ends are formed end portions 13, 14 which taper away from the central portion 12 and the plate 10 is shaped into a corrugated or embossed surface, the shaping of the corrugated or embossed surface in the central portion 12 being different from the shaping of the corrugated or embossed surface of the end portions 13, 14. The shaping of the end portions 13, 14 serves to guide air to the central portion 12 and to generate turbulent flow.

(18) The expanded metal structure 1010 which constitutes the supporting member 101 of the heat and humidity exchange plate 10 can be produced from both sheets and coils. In an exemplary embodiment according to the invention, production from coils is preferred due to very low thickness of the starting metal foil 1011. The expanded metal structure 1010 is produced by making a series of cuts in the metal foil 1011 which is drawn from a coil 1012 disposed on a feeding roll 5, in the transverse direction, and after slitting, the metal foil 1011 is stretched in the longitudinal direction.

(19) The slitting device is shown schematically in FIG. 3 only by a slitting knife 6, which is arranged between the feeding roll 5 and a withdrawal device 7. After slitting, cuts 1013 are formed in the metal foil 1011 behind the cutting edge 61. The foil 1011 with the cuts 1013 passes through the withdrawal device 7 formed by a pair of rollers and is subjected to a longitudinal tensile stress induced by a drawing device 8 formed by a pair of rollers which rotate at a higher speed than the rollers of the withdrawal device 7. By stretching, the cuts 1013 expand in the longitudinal direction, and holes 1014 are formed in the metal foil. After stretching, the material has a slightly corrugated surface because the cut portions rotate slightly vertically during drawing, as shown in FIG. 5. Therefore, it is necessary to subsequently roll this material, which is shown in FIG. 3, by a rolling device 81. This results in a flat surface with holes and a metal expanded structure 1010 is formed, which is subsequently wound on a winding roll 9. The amount of elongation in the longitudinal direction is in the range of 20 to 70% of the original length of the metal foil.

(20) Another variant, not shown in detail, is the formation of holes 1014 in the metal foil 1011 immediately after it has been slit by the slitting knife 6, wherein the withdrawal device 7 of the slit metal foil 1011 is omitted in the device and the longitudinal tension in the metal foil 1011 is achieved by the different speeds of the feeding roll 5 and the rolling device 81. In this embodiment, holes 1014 are formed immediately after being slit, but again, they are formed without any loss of material of the metal foil 1011. Here, too, it is a completely waste-free technology.

(21) Due to the fact that in the production of the expanded metal structure 1010 the ductility of the used metal material is usually exhausted and due to the fact that in the last step of the production of the heat and humidity exchange plate 10 according to the invention embossed elements are created, ensuring the turbulent flow of the passing air for better heat and moisture transfer between the exhaust and supply air, the ductility of the material must be restored. This is achieved by a controlled annealing process of the expanded metal structure 1010, either sequentially in the area of the structure or preferably in its finished coil, where the coil of the expanded structure is transferred to an annealing furnace in which annealing takes place. In this case, it is advantageous to monitor the temperature also in the coil cavity during annealing. The annealing process is usually followed by activation of the surface of the expanded metal structure 1010, for example chemically by using isopropanol or physically by plasma treatment using ionization. Also, the corresponding side of the polymeric vapour-permeable membrane 102 may be activated in the same manner. This is followed by connecting at least one side of the expanded metal structure 1010 to the vapour-permeable polymeric membrane 102, for example, by gluing after applying the glue from a glue applicator 104, as shown in FIG. 2, or by thermocompression. Thus, a semi-finished product is formed 103 for the production of the heat and humidity exchange plates 10. The connection of the expanded metal structure 1010 to the thin vapour-permeable polymeric membrane 102 is performed over the entire width of the expanded metal structure 1010 and the strip of the vapour-permeable polymeric membrane 102, as shown in FIGS. 7a, 7b, 7c. It is apparent from a detail in FIG. 7c that the supporting member 101 consisting of a strip of the expanded metal structure 1010, is connected to the vapour-permeable polymeric membrane 102 by means of a layer of glue 1041. The semi-finished product 103 thus created can be used for any dimensions of heat exchange plates and humidity exchange plates 10. The vapour-permeable polymeric membrane 102 can be formed on the expanded metal structure 1010 also by applying a liquid polymer and curing it.

(22) Subsequently, corrugated or embossed structures are formed by omnidirectional deformation, for example by pressing, and the excess material 1031 is cut to form the heat and humidity exchange plate 10 of the desired shape. This can be done in one operation or separately. This process is schematically shown in FIG. 8a, where a shaping plate 130 provided on its circumference with a cutting knife 131 rests on the semi-finished product 103 formed by a metal expanded structure 1010 and a vapour-permeable polymeric film 102, whereupon the heat and humidity exchange plate 10 is formed and cut out after its tilting off. The plates 10 produced are then joined into assemblies to form a counterflow enthalpy heat exchanger 1, whereby the connection of the individual plates 10 is made by pressing with a double hem 11 in order to seal the joint perfectly and to prevent unwanted secondary air leakage at the plate 10 joints because the expanded metal structure 1010 provided with the vapour-permeable polymeric membrane 102 is formed over the entire surface of the plate 10 and there is a risk of parasitic air leakage if the connection between the plates 10 is imperfect.

INDUSTRIAL APPLICABILITY

(23) The invention can be used for economical air conditioning and ventilation of residential and industrial buildings, where it ensures the supply of fresh air with highly efficient heat and moisture recovery from the exhaust air. In winter, there is no discomfortable excessive reduction of internal humidity in the building. Furthermore, there is no need to solve condensate drainage from the heat exchanger in the ventilation unit. In addition, there is no risk of condensate freezing in the heat exchanger and therefore there is no need to address its frost protection, for example, it is not necessary to install an energy-inefficient electric outdoor air preheater in the ventilation system.

(24) List of References

(25) 1 counterflow enthalpy heat exchanger

(26) 10 heat and humidity exchange plate

(27) 101 supporting member

(28) 1010 expanded metal structure

(29) 1011 starting metal foil

(30) 1012 coil of the starting metal foil

(31) 1013 cuts in the metal foil

(32) 1014 holes in the metal foil

(33) 102 vapour-permeable polymeric membrane

(34) 103 semi-finished product for the production of heat and humidity exchange plates

(35) 104 glue applicator

(36) 1041 glue

(37) 11 double hem of the plate joint

(38) 12 central portion of the plate

(39) 13,14 end portions of the plate

(40) 2 air channel in direction A

(41) 3 air channel in direction B

(42) 4 exchanger housing

(43) 5 feeding roll

(44) 6 slitting knife

(45) 61 cutting edge

(46) 7 withdrawal device of the cut metal foil

(47) 8 drawing device

(48) 81 rolling device

(49) 9 winding roll of the expanded metal structure

(50) 130 forming plate

(51) 131 cutting knife