WO2009008732A2

WO2009008732A2 - Heat exchanger

Info

Publication number: WO2009008732A2
Application number: PCT/NO2008/000252
Authority: WO
Inventors: Morten Gulliksen
Original assignee: Eltek Valere As
Priority date: 2007-07-06
Filing date: 2008-07-03
Publication date: 2009-01-15
Also published as: WO2009008732A3; GB2450760A; GB0713205D0

Abstract

The present invention relates to a plate stack for use in a heat exchanger, a heat exchanger and a method for exchanging heat between two flowing fluids. A plate stack for use in a heat exchanger comprising at least two first plates 41A and at least one second plate 41B and where the plates at two opposite edges comprises at least one raised arc inlet portion and one sunken arc inlet portion arranged when assembled form an opening for the first fluid flow between the one first plate 41A and the one second plate 41B and an opening 403,403B for the second fluid flow between the one second plate 41B and the second first plate 41A'. The invention also regards a heat exchanger where such a plate stack is used and a method for exchanging heat between two fluid flows. Such a heat exchanger may for instance be used in an outdoor cabinet, and gives a possibility of crating a hermetic cooling and preventing dust from entering the cabinet.

Description

HEAT EXCHANGER

The present invention regards a plate stack for use in a heat exchanger, a heat exchanger and method for exchanging heat between two fluid flows.

An aim with the present invention is to provide a compact and efficient heat exchanger. There is also an aim to provide a heat exchanger which is easy to assemble and use.

These aims are achieved with a plate stack for use in a heat exchanger, a heat exchanger and method as defined in the following claims. Alternative embodiments are described in the dependent claims and following description. The present invention regards according to a first aspect a plate stack for use in a heat exchanger comprising at least two first plates and at least one second plate. These plates are arranges so that the second plate is arranged between the two first plates. There may be several first and second plates in the plate stack according to the invention, arranged alternating to form a stack. There may also be two second plates and one first plate. The plates are formed with a mainly rectangular main body plate. The main body plate comprises at two opposite edges at least one raised arc inlet portion and one sunken arc inlet portion. These are arranged with a sunken arc inlet portion of one first plate abutting a raised arc inlet portion of one second plate and a raised arc inlet portion of a second first plate abutting a sunken arc inlet portion of the one second plate. Such a configuration forms an opening for a first fluid flow between the one first plate and the one second plate between a raised arc inlet portion of the one first plate and a sunken arc inlet portion of the one second plate and an opening for the second fluid flow between the one second plate and the second first plate between a raised arc inlet portion of the second plate and a sunken arc inlet portion of the second first plate.

By this one has achieved a configuration with openings for a first fluid flow between two plates and openings for a second fluid flow between two other plates, giving that the first fluid flow may flow in a space between two plates and the second fluid flow may flow in a neighboring space. According to one aspect a plate in the plate stack is formed with alternating sunken and raised inlet portions along two opposite edged of the plate. This gives that there is formed alternating opening for the first and second fluid flow between the plates, along the edges of plates. According to another aspect the arc inlets portions seen transverse to the main body plate, forms a part circular shape. In another embodiment this arc inlet portion may form a part oval, polygonal, wedge formed, or other shaped inlet portion. By having a shaped arc inlet portion, instead of a straight edge, the inlet area towards the space between two plates is increased. Another element is to create as uniform flow as possible in the space between the plates, and at the same time achieve a low speed on the flow after the inlet portion, for thereby get a thermal boundary layer which is as even and thick as possible. There is also the aspect of keeping as long a distance for heat exchanging as possible in such manner that most of the plate area is used for heat exchange. All these aspects should be considered when forming the shape of the arc inlet portion to the space between the plates in the plate stack.

According to another aspect of the invention the arc inlet portions are formed with a flange part encircling the arc inlet portions. This flange part has a main plane mainly parallel to and shifted in relation to a plane for the main body plate. These flange parts are connected to the main body plate by a transition portion. In another embodiment these flange parts and transition portions may be formed more continues as a part conical, or with several stepped surfaces.

According to another aspect a flange part of one inlet portion is abutting a flange part of a neighboring inlet portion, by this the transition portions of two neighboring inlet portions are joined at the edge of the plate forming a continues edge part between the neighboring flange parts. The edge of a plate will thereby be formed when seen in the direction of the plate plane with an end part, a transition portion, an flange portion ending in a raised arc inlet portion, which by the shape will be withdrawn inwards in the plate from the edge, which arc inlet portion on the other side is continued with a flange portion and a combined transition portion of two neighboring arc inlet portions, a flange portion and then a sunken arc inlet portion and then a flange portion, a combined transition portion etc. This is continued until one achieves the desired size of the plate, where it is ended in another end part.

According to another aspect the plate comprises at least one transverse protrusion and or groove, running at least a part of the distance between two opposite arc inlet portions. In one embodiment these protrusions and or grooves are formed running between raised arc inlet portions. Raised arc inlet portions on a first plate is arranged shifted in relation to raised arc inlet portion of a second plate and the protrusion of a first plate is thereby arranged shifted in relation to the protrusion of a second plate. The protrusion of a first plate is thereby arranged in between the protrusions of a second plate, seeing these plates on top of each other from above. A protrusion of a second plate is thereby arranged between the sunken arc inlet portions of a first plate, etc. These protrusions and or grooves are formed with a height from the main body of the plate to provide support so that the different plates stacked on top of each other is kept with a distance, and thereby space between them. These protrusion and or grooves will also provide guidance for the fluid flow in the space wherein the protrusions and or grooves extend. The plates may also be formed with alternating grooves and protrusions with respect to the raised and sunken arc inlet portions. One may in one embodiment also form one plate with protrusions and or grooves between all the opposite arc inlet portions and the second plate without protrusions and or grooves. The plates will also be formed with an end closing on the edges transverse to the edges comprising the arc inlet portions.

In one embodiment of the plate stack the plates are stacked with a distance of between 0,6 and 2 mm between the plates, favorably between 0,8 and 0,9 mm distance between the plates. The inlet arc portions together with the flange portions forms in this embodiment a distance repeated along the edge of from 5 to 30 mm favorable between 10 to 20 mm.

The present invention also regards a heat exchanger forming a first flow path for a first fluid and a second flow path for a second fluid. The first flow path comprises a centrally located inlet guiding a fluid flow from an axially direction to a radial direction, at least one plate stack section for heat exchanging with the second fluid and at least one outlet. This first flow path is arranged to give a flow path mainly in a common plane from downstream of the inlet to the outlet of the heat exchanger and also a flow path as straight as possible without deviating the fluid flow more than necessary. The second flow path comprises a centrally located inlet guiding a flow from an axially direction to a radial direction, a first transition part guiding the flow from the inlet to one upstream stack guide element, the upstream stack guide element, the at least one plate stack section and another downstream stack guide element, and a second transition part guiding the flow from the downstream stack guide element to at least one outlet.

According to an aspect of the invention the inlet of the first flow path and the inlet of the second flow path are arranged with a mainly common centre axis. In an embodiment the inlets are formed by elements arranged rotating relative the rest of the heat exchanger. These rotating elements thereby drive the fluid flows through the heat exchanger. There may be one common drive unit for the rotating elements forming the inlets and thereby drive the elements forming the inlets at a common rotating speed or there may be different drive units, operating the inlets at different rotating speed. With a common drive unit this may be arranged between the two elements forming the inlets. The inlets may be formed by one common element or two elements attached to each, or each separately attached to a drive unit. In one embodiment the flow direction in the inlet of the first flow path is in a direction mainly opposite the flow direction in the inlet of the second flow path. This may in one embodiment be achieved by having the elements forming the inlets arranged back to back, and possibly with the drive unit arranged between the inlets.

The heat exchanger comprises according to an aspect a plate stack section comprises several plates positioned next to each other, forming channels or spaces between them. In one embodiment neighboring spaces guide fluid flows in opposite directions, forming a counter flowing plate stack section. In one embodiment the plates are formed with a main plate plane with a normal axis mainly parallel to a centre axis of the inlets. In another embodiment the normal axis of the main plate plane may be mainly transverse to the centre axis of the inlet. According to an aspect there are one plate stack section arranged on at least one side of the heat exchanger. There may be formed a row of plate stack sections. There may also be plate stack section arranged on several sides of the heat exchanger, possibly two opposite sides of the heat exchanger, giving two outlet directions for the first fluid flow.

According to an aspect of the invention the plate stack is a plate stack as explained above. According to another aspect the outer shape of the heat exchanger may be a mainly rectangular box. This gives a shape which is easily suitable for many applications. According to this embodiment the inlets are arranged in the middle of two opposite sides. These inlets have in this embodiment a common centre axis. The outlets are arranged with one outlet of the first flow path on one side connecting the two opposite sides with the inlets, and one outlet of the second flow path on another side, connecting the two opposite sides with the inlets. In one embodiment there may be two outlets of the first flow path and these arranged on opposite sides of the mainly rectangular box. Such a configuration gives a division of the first fluid flow into two first fluid flows. Also the second fluid flow will within the heat exchanger be divided into two fluid flow paths within the heat exchanger, which two flow paths are joined before the outlet of the second fluid flow path.

According to the invention there is upstream the plate stack sections in the second flow path, within the heat exchanger arranged at least one stack guide element. According to an aspect this stack guide element will form at least one guide channel for the second flow path, formed with an inlet opening in a plane, which plane axis is mainly parallel to a centre axis of the heat exchanger, and an outlet opening of this guide channel is facing the plate stack and arranged with an orientation mainly 90 degrees turned in relation to, i.e. transverse to the inlet opening. In this configuration a cross section of the guide channel transverse to a centre axis decreases in a direction away from the inlet. One stack guide element may be formed with a plurality of guide channels arranged next to each other but with a distance between them for guiding the first flow path in between and into the plate stack section. An inlet of such a guide channel for the second flow path will be elongated, and these inlets will be arranged with the long side of the inlet next to a long side of the neighbouring inlet. Also outlets of the guide channel may be formed in a similar manner, giving a sort of flat shaped guide channels arranged next to each other with distance between them. The outlets of these guide channels will cooperate with arc inlet portions of the first and second plates in the plate stack which arc inlet portions are arranged next to each other, seen along the centre axis of the heat exchanger, forming openings to every other space between the plates in the plate stack. According to the invention there is also arranged at least one stack guide element downstream of the plate stack sections with a shape mainly equal to the stack guide element arranged upstream of the plate stack sections, arranged symmetrically about a midplane of the plate stack section. The distance between the guide channels on both sides of the plate stack, forms guidance for the first fluid flow into or out of the neighbouring openings toward the other spaces between the plates in the plate stack, thereby giving possible counter flow of the first and second fluid flows through the plate stack. It is strived to get an almost equal amount of flow in both the first and the second fluid flow path. The cross section openings through the guide channels in the stack guide element are designed to keep a steady flow velocity, through the plate stack. Normally the upstream stack guide element will be positioned further away from the inlet of the heat exchanger, than the downstream stack guide element. This gives that the second fluid flow is turned several times through the heat exchanger. According to a further aspect the second transition part is formed with a main flow direction and where a cross section of the flow path transverse to this main flow direction, increases gradually along the main flow direction. This second transition part may in one embodiment be connected to the plate stack guide element downstream of the plate stack sections, with the row of elongated outlets. The main flow direction in the second transition part will be in a direction mainly transverse to the elongated outlets, and where the cross section of the second transition is formed so that it forms a tunnel with the larger cross section at the outlet. This gives that the elongated outlet of a guide channel with the longest distance from the outlet of the heat exchanger leads out in a section of the second transition part with the smallest cross section and the elongated outlet closest to the outlet of the heat exchanger leads out in a section of the second transition part with the largest cross section, giving space in the second transition part adapted to the amount of flow though that part of the transition part. This gives a more even flow through the heat exchanger. According to an aspect the first transition part and second transition part of the second flow path is mainly formed by the outer shell of the heat exchanger comprising top and bottom sides and side walls, a flat dividing wall and a middle curved wall. The outer boundary of the first transition parts formed by a portion of the bottom side and a part of a side wall. The connection between the bottom side and the part of the side wall is given a curved shape to help form the first transition part of the second fluid flow path. The other boundary of the first transition part is the middle curved wall. This middle curved wall also forms a boundary of the second transition part, and the shape of this middle curved wall is thereby formed to give a good fluid flow through both the first and second transition part. The second transition part is on the other side restricted by the dividing wall, which is a plate wall with a main plane transverse to the centre axis of the heat exchanger. This dividing wall is according to an aspect a wall also extending between the inlets for the first and second fluid flow. The inlet of the upstream stack guide element and outlet of the downstream stack guide element will normally be arranged in the plane of this dividing wall. In an embodiment there are arranged holes through this dividing wall, forming boundary of these inlets and outlets.

According to a further aspect of the invention there may be arranged vanes within the flow paths in the heat exchanger, there may also be arranged outside vanes to guide the fluid flow into or out of the inlets and or outlets of the heat exchanger. These outer vanes may be formed from the inlet and outwards in a radial direction in a distance from the inlet. There may also be vanes formed on the edge between the top side and side walls. These outer vanes may be formed so that they support a cloth arranged stretching across the top side and the inlet. This cloth may be arranged across the inlet of the first fluid flow to prevent particles from entering the heat exchanger, and the vanes gives a large area for fluid flow through the cloth.

The cloth may also be a long length of cloth arranged rolled up on one side wall of the heat exchanger, and stretched up and across the top wall and down to a roll on the opposite side wall, thereby giving the possibility of changing the cloth across the inlet by rolling the cloth a length until a fresh cloth is arranged across the inlet. The invention also comprises a method for heat exchanging between a first and a second fluid. According to the method a first fluid flow is guided through a centrally located inlet, where the inlet is guiding the fluid flow from a mainly axially direction to a radial direction, relative a centre axis of the heat exchanger. Thereafter the fluid flow is guided to and through a plate stack section and then through an outlet. From downstream of the inlet to the outlet one thereby gives the fluid flow a main flow pattern transverse to the flow direction into the inlet, i.e. a flow pattern for the first fluid flow in a mainly radial direction from downstream of the inlet. Further the second fluid flow is guided through a centrally located second inlet guiding the second fluid flow from an axially direction to a mainly radial direction. Thereafter the fluid flow is guided through a first transition part guiding the flow from downstream the inlet to one upstream stack guide element and through this and then through the plate stack section and a downstream stack guide element, , thereafter through a second transition part guiding the flow from the downstream stack guide element and to an outlet. According to an aspect the fluid flow through the at least one outlet of the first fluid flow is guided in a first direction, and the fluid flow through the outlet of the second fluid flow is guided in a second direction mainly transverse to the first direction. According to another aspect the fluid flows through the plate stack section is a counter flow pattern between the first and second fluid flow through the plate stack section. According to one aspect of the invention the drive unit comprises a compact electrical engine, possibly positioned centrally between the inlets. The electrical engine can for example be a permanent magnetized synchronic engine, where the stator is fixed to the outer structure of the heat exchanger and where a fist part of the rotor is fixed the inlet in the first flow path and a second part of the rotor is fixed to the inlet of the second flow path. This drive unit may be formed with minimal outstretch in a direction of the centre axis of the heat exchanger, i.e. be a compact and relatively flat disc drive unit. This drive unit will also produce minimal heat during use. The invention shall now be explained with an embodiment and with reference to the accompanying drawings, where;

Fig. 1 shows a cross section through a part of the heat exchanger,

Fig. 2 shown a perspective sketch with a cover removed, showing the pattern of the first fluid flow, Fig. 3A-C shows different sketches showing the elements forming the second fluid flow,

Fig. 4 shows a perspective view of the outer structure, with one element removed, Fig. 5 shows a part sketch of one possible system for building plate stack sections, Fig. 6 shows an part elevated sketch of plates used in the system of fig. 5, and Fig. 7 shows the plates of fig. 6 seen partly from above.

In the figures there is shown different aspect of a heat exchanger. The following description refers to all figures, but will refer to specific figures to clarify specific features.

The heat exchanger has an outer structure 10, comprising a mainly rectangular top side 11 and a bottom side 12 and connecting side walls (top and bottom is used to indicate the sides in figure 1. The heat exchanger may be turned different ways during use, and the use of top and bottom should therefore not be considered limiting in this sense). The first fluid through the heat exchanger will follow the first flow path 20, indicated with arrows. The flow path 20 comprises an inlet 21, with an upstream opening 22 with a centre axis, leading through guiding vanes 23 through to a downstream opening 24. Through the inlet 21 the first flow path has changed direction from a mainly axial direction to a radial direction. The inlet 21 is arranged rotating relative the outer structure 10, and this is done by bearing arrangement between the inlets and the outer structure and a drive unit 60 positioned between the inlet 21 of the first flow path 20 and an inlet 31 of a second flow path 30. The inlet 21 is also formed with outer guide vanes 28 which are formed to centralize the outer structure 10 relative the inlet 21 both during use and when assembling the heat exchanger. From downstream of the inlet 21 the first flow path is divided and leads through plate stack sections 40 arranged on two opposite relative sides of the heat exchanger and through outlets 25 arrange in two first side walls 13 of the outer structure 10. The plate stack section 40 may comprise several sections 40 forming two rows, as indicated in fig. 2 where only one plate stack section 40 is shown, but where on may see that there may be three additional plate stack sections 40 forming two rows. The flow path from downstream of the inlet 21 is mainly in a plane transverse a central axis 61 of the heat exchanger where this central axis 61 coincides with a rotational axis for the inlets and drive unit 60.

The second fluid will follow a separate second flow path. The second flow path 30 also comprises an inlet 31 , where the flow in the second flow path is in a direction opposite the first flow path direction in the inlet 21, and where the inlet 31 is arranged with a common rotational axis 61 with the inlet 21 of the first flow path 20. The inlets 31,21 also comprises holes 27,37 for cooling the drive unit 60 arranged between the inlets 21,31. The inlet 31 also comprises outer guide vanes 38 for centralizing the inlet 31 relative the outer structure 10. Also this inlet 31 guides the flow path from an upstream opening 32 with an axial direction through guide vanes 33 to a downstream opening 34 with a radial direction. Downstream of the inlet 31 the flow path is guided in a first transition part 35 towards a stack guide element 50, through the plate stack section 40 out through a second stack guide element 50, through a second transition part 36 and out through an outlet 39 of the second flow path 30. The first transition part 35 is formed by an outer wall of the outer structure 10, i.e. the bottom side and side walls 13, 14 and a middle curved wall 37. This curved wall 37 as better shown in fig. 3C, forms a barrier between the first transition part 35 and a second transition part 36, where the first transition part 35 is formed on the outside of the curved wall 37 and the second transition part 36 is formed between the curved wall 37 and a dividing wall 16 arranged in a plane stretching mainly transverse to the centre axis and arranged between the elements forming the two inlets 21 , 31 of the heat exchanger. As one may see from fig. 3C the second transition part 36 is formed with an increasing cross section towards the outlet 39 of the second flow path 30. In the second flow path there is upstream of the plate stack section 40 arranged stack guide element 50, comprising several fluid guide channels, with an upstream inlet 51, forming an elongated opening of the channel. The channel ends in a downstream outlet 53 facing the plate stack section 40. The inlet 51 and the outlet 53 are arranged mainly transverse each other, and joined on the side facing away from the plate stack section 40 by a curved outer surface 52, giving a decreasing cross section transverse to the centre axis of the channel away from the inlet 51. In a similar manner there is arranged a stack guide element 50 downstream of the plate stack section 40. This stack guide element 50 has an opposite configuration with an upstream inlet 54, mainly parallel with a centre axis of the heat exchanger and a downstream outlet 56 mainly parallel with the dividing wall 16. There is in this also a connecting curved outer surface 55 connecting an end of the inlet 54 with an end of the outlet 56. The stack guide element 50 is formed by several elements forming the guide channels and connecting an outlet with an inlet, as shown in the figures. The middle curved wall 37 also has a shape guiding the second flow path from two sets of plate stack sections arranged on two sides of the inlet 31 so that the flow path of the second fluid will flow through the plate stack sections 40 in a direction towards the inlet 31, i.e. for a segment of the plate stack section in a radial direction, and thereafter out of the plate stack section 40 on the two sides of the inlet 31 and along the inlet 31 and out through one common outlet 39, arranged in a second side wall of the heat exchanger, se fig. 3A and 3B.

The heat exchanger may also in one embodiment comprise outer vanes 15 for guiding the fluid flows into the inlets 21 , 32, as shown in fig. 4. As shown in fig. 5 the plate stack section 40 may be built by layering of plates 41 on top of each other, with a main plate plane 42 parallel with the dividing wall 16. The plates 41 may comprise protrusions 43 and grooves 44. The stack guide element 50 may also form guides and bearings for the plate stack sections 40, making correct assembly easy. In fig, 5 a part of a the plate stack section 40 is shown in relation to one stack guide element 50, the stack guide element 50 on the opposite side of the plate stack section 40 is removed. There is also indicated a part of another plate stack section 40' arranged in a row with the first plate stack section 40. Stack guide elements 50 are also removed in relation to this other plate stack section 40'. In fig. 6 there is shown a more detailed part of a part of a plate stack section 40. The plate stack section 40 comprises plates 41, in the form of a first plate 41 A and a second plate 4 IB, layered one on top of the other forming spaces between them for the first and second fluid flow. The first plate 41 A with a main body plate 410 is along to opposite edges 412 (see fig. 7) formed with a repetitive pattern of raised arc inlet portions 413 and sunken arc inlet portions 417, forming when seen along the centre axis of the heat exchanger half circles extending inn from the outer edge 412 of the plate 4 IB. These arc inlet portions 413,417 are formed with alternating raised 413 and sunken 417 arc inlet portions. An arc inlet portion 413,417 is also formed with a flange part 414,418 encircling the arc inlet portions 413,417 where these flange parts 414,418 are formed mainly parallel to the main body 410 but staggered on opposite sides of the main body 410 to form raised and sunken arc inlet portions 413,417 respectively. The flange parts 414,418 are connected to the main body 410 by transition portions 415,419. A raised arc inlet portion 413 is arranged neighboring a sunken arc inlet portion 417 so that the transition portion 415 is joined by a transition portion 418 forming a common transition portion at the edge 412 of the main body 410. The other edges 41 1 are formed with end systems.

The plate stack 40 has between first plates 41 A arranged second plated 4 IB, which has a similar configuration, but arranged so that when the plates are arranged on top of each other a raised arc inlet portion 427 with an encircling flange portion 428 and transition portion 429 is abutting a sunken arc inlet portion 417 with flange portion 418 of the first plate 4 IA, so that the flange portions 428,418 are abutting each other and thereby closing the space in between these two plates. Next to this a sunken arc inlet portion 423, with an associated encircling flange portion 424 and a transition portion 425 of the second plate 41 B is arranged to cooperate with a raised arc inlet portion 413 of the first plate 41 A to form an opening 403 into the space between the second plate 41 B and first plate 41 A for the second fluid flow. By the repetitive pattern there is created a row of opening 403 on top of each other which cooperate with a guide channel to guide a fluid flow to or from every other space between the plates and next to these openings 402 openings to the other spaces between the plates. The pattern is similar on the opposite edge 412,422 of the plates and thereby forming opening 402B opposite opening 402 and visa versa, as best can bee seen from fig. 7. The plates 4 IA, 41 B also comprises protrusions 43 and grooves 44, forming the opposite configuration on the opposite side of the plate 41 A,41B. These protrusions 43 are formed as a raised part of the plate, which raised part is stretching in a direction from one raised arc inlet portion 413, 427 to an opposite raised arc inlet portion 413,427. These protrusions are ended in a distance from the arc inlet portions 413,427, and will work as elements for preventing the spaces between the plates to collapse and also to guide the fluid flow through the plates. The plates 41A and 41B are also formed with stack guides 45, formed as a truncated cone, raised from the main body plates 410,420. These stack guides 45 will guide the plates 4 IA, 41B relative each other and also limit the distance between the plates 41 A, 41 B by the shape of the cone.

The outer structure of the heat exchanger may be formed by two elements, one comprising the top side and four half side walls, and the other element comprising the bottom side and four half side walls, which elements are joined at the dividing plate. This gives an easy assembly.

As one can understand from the description above the size of the plate stack both with regards to the number of arc inlets along one edge and the number of plates arranged on top of each other may be varied and adapted to the necessity for heat exchanging at the actual use, thereby giving a large range of configurations of a heat exchanger according to the invention. The form and shape of the first and second fluid flows through the heat exchanger gives good heat transferal between the two fluid flows. The heat exchanger and or the plates in the plate stack section are according to an embodiment made of a polymer. Even if this material in general has low generally low conductivity, the plates in the plate stack section are thin and the total form of the heat exchanger is so that there is good conductivity between the fluids flowing through the heat exchanger.

A heat exchanger according to the invention may for instance be used in an outdoor cabinet, and gives a possibility of crating a hermetic cooling and preventing dust from entering the cabinet.

The present invention has now been explained with an embodiment. A skilled person will understand that there may be made several alterations and modifications to the embodiment as shown within the scope of the invention as defined in the following claims.

Claims

1. Plate stack for use in a heat exchanger comprising at least two first plates (41 A) and at least one second plate (41B), where the second plate (41B) is arranged between the two first plates (41A, 41A') and where the plates (41 A, 41A', 41B) are formed by a mainly rectangular main body plate (410, 420), whe re i n the main body plate (410,420) at two opposite edges (412,422) comprises at least one raised arc inlet portion (413,427) and one sunken arc inlet portion (417,423), arranged with a sunken arc inlet portion (417) of one first plate (41A) abutting a raised arc inlet portion (427) of one second plate (41B), and a raised inlet portion (413) of a second first plate (41A') abutting a sunken arc inlet portion (423) of the one second plate (41B), forming an opening (402,402B) for the first fluid flow between the one first plate (41A) and the one second plate (41B) between a raised arc inlet portion (413) of the one first plate (41A) and a sunken arc inlet portion (423) and an opening (403,403B) for the second fluid flow between the one second plate (41B) and the second first plate (41A') between a raised arc inlet portion (427) of the second plate (41B) and a sunken arc inlet portion (417) of the second first plate (41A').

2. Plate stack according to claim 1, wh e r e i n a plate (4 IA, 41B) is formed with alternating sunken and raised inlet portions (413,417,423,427) along two opposite edged (412,422) of the plate (41 A, 41B).

3. Plate stack according to claim 1, wh e r e i n the arc inlets portions (413,417,423,427) seen transverse to the main body plate, forms a part circular shape.

4. Plate stack according to claim 1, wh e re i n the arc inlet portions (413,417,423,427) are formed with a flange part (414, 418, 424,428) encircling the arc inlet portions(413, 417,423,427), with a main plane mainly parallel to and shifted in relation to a plane for the main body plate (410,420).

5. Plate stack according to claim 4, wh e r e i n the flange part (414, 418, 424,428) is connected to the main body plate (410,420), by a transition portion (415,419, 425, 429).

6. Plate stack according to claim 5, w h e r e i n a flange part (414, 418, 424,428) of one inlet portions (413,417,423,427) is abutting a flange part (414, 418, 424,428) of a neighboring inlet portion (413,417,423,427), joining the transition portions (415,419, 425, 429) at the edge (412,422)

7. Plate stack according to claim 1, wh e re i n a plate (4 IA, 41B) comprises at least one transverse protrusion (43) and or groove (44), running at least a part of the distance between two opposite raised arc inlet portions (413,425).

8. Heat exchanger forming a first flow path (20) for a first fluid and a second flow path (30) for a second fluid, w h e r e i n the first flow path (20) comprises a centrally located inlet (21) with a centre axis (61), guiding a fluid flow from an axially direction to a radial direction, at least one plate stack section (40) and at least one outlet (25), arranged to give a flow path from downstream the inlet (21) to the outlet (25) mainly in a common plane, and the second flow path (30) comprises a centrally located inlet (31) guiding a flow from an axially direction to a radial direction, at least one first transition part (35) guiding the flow from the inlet (31) to a stack guide element (50) leading into the plate stack section (40), the at least one plate stack section (40) and a stack guide element (50) downstream of the plate stack section (40) and at least one second transition part (36) guiding the flow from the plate stack section (40) to at least one outlet (39).

9. Heat exchanger according to claim 8, whe r e i n the inlet (21) of the first flow path (20) and the inlet (31) of the second flow path (30) are arranged with a mainly common centre axis (61).

10. Heat exchanger according to claim 9, wh e r e i n the inlets (21,31) are formed by elements arranged rotating relative the rest of the heat exchanger.

1 1. Heat exchanger according to claim 10, wh e r e i n there is a common drive unit (60) for rotating the inlets (21 ,31).

12. Heat exchanger according to claim 9, wh e r e i n the flow direction in the inlet (21) of the first flow path (20) is in a direction mainly opposite the flow direction in the inlet (31) of the second flow path (30).

13. Heat exchanger according to claim 8, whe r e i n a plate stack section (40) comprises several plates (41A,41B) positioned side by side, forming spaces between them, where neighboring spaces guide fluid flows (20,30) in opposite directions.

14. Heat exchanger according to claim 8, wh e r e i n there are several plate stack sections (40.40') arranged in a row on at least one side of the heat exchanger.

15. Heat exchanger according to claim 13, whe r e i n the plates (41A,41B) has a main plate plane with a main plate plane axis mainly parallel to a centre axis (61) of the inlets (21,31).

16. Heat exchanger according to claim 8, w h e r e i n the outer shape of the heat exchanger is a mainly rectangular box, the inlets (21,31) are arranged in the middle of two opposite sides (11 , 12), and the outlets (25,39) are arranged with the outlets (25) of the first flow path (20) on one side (13) connecting the two opposite sides (11,12) with the inlets (21,32), and an outlet (39) of the second flow path (30) on another side (14), connecting the two opposite sides (11,12) with the inlets (21,31).

17. Heat exchanger according to claim 8, w h e r e i n there upstream the plate stack section (40) in the second flow path (30) is arranged at least one stack guide element (50), forming at least one guide channel formed with an inlet opening (51) arranged in a plane of a first plate in the plate stack section (40), and an outlet opening (53) facing the plate stack section (40) mainly parallel with the centre axis (61), where a cross section of the channel transverse to a centre axis (61) decreases in a direction away from the inlet opening (51).

18. Heat exchanger according to claim 17, wh e r e i n there are arranged at least one stack guide element (50) downstream of the plate stack sections (40) with a shape mainly equal to the stack guide element (50) arranged upstream of the plate stack sections (40) and arranged symmetrically about a midplane of the plate stack section (40).

19. Heat exchanger according to claim 8, whe re i n the second transition part (36) is formed with a main flow direction and where a cross section of the flow path transverse to this main flow direction, increases gradually along the main flow direction.

20. Method for heat exchanging between a first and a second fluid, wh e r e i n a first fluid flow (20) is guided through a centrally located inlet (21) guiding the flow from a mainly axially direction to a radial direction, thereafter to and through a plate stack section (40) and then through an outlet (25) giving a main flow pattern from the inlet (21) to the outlet (25) in one plane transverse to the flow direction into the inlet (21), and where the second fluid flow (30) is guided through a centrally located inlet (31) guiding the fluid flow (30) from an axially direction to a radial direction, then through a first transition part (35) guiding the flow from the inlet (31) to a stack guide element (50), through the stack guide element (50) and the plate stack section (40) and a downstream stack guide element (50), thereafter through a second transition part (36) guiding the flow from the downstream stack guide element (50) to an outlet (39).

21. Method according to claim 20, whe re i n the first fluid flow (20) through the first outlet (25) is guided in a first direction and the second fluid flow (30) through the second outlet (39) is guided in a second direction mainly transverse to the first direction.