PROCESS TO MANUFACTURE AN INTERCONNECTED STACK OF THERMOPLASTIC FRAMES

Abstract

The invention is directed to a process to manufacture an interconnected stack of thermoplastic frames having two sides by stacking the thermoplastic frames to obtain a stack of frames such that the facing sides of two neighbouring frames are in contact with each other at a contact area. When stacking a longitudinal conduit is formed which runs along the length of the stack and a branched conduit is formed at the contact area. The interconnected stack of thermoplastic frames are obtained by supplying a pressurised melt of a plastic material to the elongated conduit and branched conduits.

Claims

1. A process to manufacture an interconnected stack of thermoplastic frames having two sides by stacking the thermoplastic frames to obtain a stack of frames such that the facing sides of two neighbouring frames are in contact with each other at a contact area, wherein as a result of stacking the frames and as a result of at least one opening present in the frame at least one longitudinal conduit is formed which runs along the length of the stack, wherein as a result of stacking the frames and as a result of an elongated gutter as present on or in at least one side of the frame at the contact area a branched conduit is formed at the contact area, which branched conduit is fluidly connected to the longitudinal conduit, and wherein a pressurised melt of a plastic material is supplied to the elongated conduit and branched conduits while the stack is held together by external means to obtain the interconnected stack of thermoplastic frames.

2. A process according to claim 1, wherein the melt of a plastic material is a melt of a thermoplastic elastomer.

3. A process according to claim 1, wherein the thermoplastic frames are polypropylene frames, polyethylene frames or polyamide frames.

4. A process according to claim 1, wherein the frames are obtained by injection moulding.

5. A process according to claim 4, wherein the frames are insert moulded work products comprising an insert consisting of a heat transfer sheet.

6. A process according to claim 5, wherein the frames are polypropylene frames and the insert is an aluminium sheet and wherein the pressurised melt of a plastic is a pressurised melt of a Styrene Ethylene Butylene Styrene Block Copolymer.

7. A process according to claim 1, wherein at least two longitudinal conduits are formed as a result of stacking the frames and wherein the at least two longitudinal conduits are not fluidly connected to each other and wherein the two elongated conduits are each fluidly connected to separate branched conduits.

8. A process according to claim 1, wherein the external means is a container having an open position and a closed position, has an interior shape which is the form negative of the interconnected stack when in the closed position and wherein the container allows positioning of the stack of thermoplastic frames and removing of the interconnected stack of thermoplastic frames when in the open position and wherein the container is provided with at least one inlet for the pressurised melt of a plastic and which at least one inlet is fluidly connected to the at least one longitudinal conduit when the container is in a closed position.

9. A process according to claim 8, wherein to the stack an added chamber is added to obtain a stack with the added chamber and wherein the container has an interior shape which is the form negative of the interconnected stack with the added chamber and wherein the added part is connected to the stack by the melt of a plastic material as supplied to the container.

10. A process according to claim 1, wherein the stack of interconnected frames is suited to be part of a plate heat exchanger.

11. An interconnected stack of thermoplastic frames having two sides wherein the facing sides of two neighbouring frames are connected by fusion bonding at a contact area.

12. An interconnected stack according to claim 11, wherein the thermoplastic frames are polypropylene frames, polyethylene frames or polyamide frames.

13. An interconnected stack according to claim 11, wherein the frames are obtained by injection moulding.

14. An interconnected stack according to claim 13, wherein the frames are insert moulded work products comprising an insert comprising a heat exchange sheet.

15. An interconnected stack according to claim 14, wherein the frames are polypropylene frames and the insert is an aluminium sheet and wherein the fusion bonding is obtainable by pressing the facing sides of the neighbouring frames in the presence of a pressurised melt of a thermoplastic elastomer.

16. An interconnected stack according to claim 11, wherein an added chamber is connected to a side of the stack.

17. An interconnected stack according to claim 16, wherein the added chamber is an injected moulded part made from the same thermoplastic material as the frames and connected to the side of the stack by fusion bonding.

18. An interconnected stack according to claim 14 as part of a plate heat exchanger.

Description

[0030] The invention will be illustrated by the following Figures.

[0031] FIG. 1 shows a frame (1) provided with an aluminium sheet (2) as an insert moulded work product. The design of the frame shows an inlet (3) for a first gas flow and an outlet (4) for the first gas flow. The frame (1) is further provided with four openings (5,6,7,8) which will form the longitudinal conduit when the frames are stacked. The frame is further provided with a system (9) of gutters as formed by ridges (10) which extend upwards for the viewer of this figure from the plane of sheet (2). For a frame having a height and width of 35?38 cm the ridges (10) may extend 3 mm. The opposite side of the frame which is not visible in FIG. 1 is flat. When the frame (1) is covered by a flat lower side of a frame (1a) as shown in FIG. 2 the gutters form the branched conduits. The dimensions of these gutters may have a cross-sectional area of between 5 and 20 mm.sup.2. Between the system (9) of ridges (10) and the openings (5,6,7,8) a fluid connection is present as shown. This results in that when a stack is formed the longitudinal conduits are fluidly connected to the branched conduits. The stack is suitably used in a horizontal position. The sides of the stack and the sides of the frames (1,1a) are therefore referred to as the upper side (11), lower side (12) and sides (13,14).

[0032] FIGS. 1 and 2 also shows an opening (18) which will not be filled with the melt of plastic material. In the interconnected stack a space for water will then be present which runs along upper side (11). By providing an inlet (not shown) to this space for water and by providing openings (not shown) to certain spaces between frames (1) and (1a) an evaporating plate heat exchanger may be obtained. The water from this space is fed to these spaces where it may evaporate. At the lower side an opening (19) may be present which is also not filled with the melt of plastic material. This space may be used to collect any not evaporated water from the above spaces. Openings (not shown) will then be present to allow water to enter these lower space running along lower side (12). A discharge for collected water (not shown) is present to discharge this water.

[0033] FIG. 2 shows a frame (1a). This frame is as frame (1) except that the shows an inlet (15) for a second gas flow and an outlet (16) for the second gas flow. When frames (1) and frames (1a) are stacked in an alternating order a row of inlets (3) will be present at one side in the lower half and a row of outlets (15) will be present at the same side (13) in the upper half of this side (13). This allows one to attach a header for supplying the first gas to the lower side of the stack and attach a header for collecting the second gas flow at the upper side of the stack making use of ridges (17).

[0034] FIGS. 3a-3d illustrate the process according to this invention. FIG. 3a shows a mould (20) and a cover (21) enclosing the mould (20) as the container in a closed position. In the mould (20) a stack (22) of eight frames (1,1a) are placed. The inner shape of mould (20) just allows positioning stack (22) in the mould. The thickness of the frames is not to scale. For clarity reasons a thicker frame is drawn such that the invention can be better illustrated. The stack (22) comprises four longitudinal conduits (23) of which two are shown. These conduits are formed by openings (5,6,7,8) in the frames (1,1a). The cover (21) is provided with four inlets (25) for the pressurised melt of a plastic. These inlets (25) are fluidly connected to the longitudinal conduits (23) as shown. The longitudinal conduits (23) are connected to the branched conduits (24) as schematically shown.

[0035] In FIG. 3b a melt of a plastic is supplied via the inlets (25) to the longitudinal conduits (23) of the stack (22) of FIG. 3a. At the contact surface between two neighbouring frames (1,1a) the melt flows from the individual longitudinal conduits (23) via the branched conduits (24) as illustrated by the smaller arrows (26). The supply of the melt of the plastic stops when all of the branched conduits are filled with the melt (27) as shown in FIG. 3c. After solidification of the melt the connected stack (22) is removed from the mould (20) by lifting the cover (21). The connected stack (22) is connected to the cover (21) by means of the solidified plastic in the inlets (25) forming one mass with the solidified plastic in the longitudinal conduits (23). By simply cutting this connection a connected stack (22) is obtained and the cover (21), after cleaning, and the mould (20) can be reused to make the next stack having the same shape.