WO2011071446A1

WO2011071446A1 - Heat exchanger with guided air flows

Info

Publication number: WO2011071446A1
Application number: PCT/SE2010/051351
Authority: WO
Inventors: Erik Helmenius
Original assignee: Ny Kraft Sverige Ab
Priority date: 2009-12-08
Filing date: 2010-12-08
Publication date: 2011-06-16
Also published as: EP2510288A1; SE0901536A1; EP2510288A4; SE534381C2

Abstract

Heat exchanger used in a ventilation system for a building. The heat exchanger comprises a plurality of parallel plates assembled by stripes of an adhesive (3), wherein the plates are channel plates (2) comprising longitudinal air channels (5). The adhesive stripes (3) are arranged in order to guide the outgoing air flow (12-14) through the heat exchanger in a cross flow and counter flow direction in relation to the incoming air flow (10, 11) guided in the longitudinal air channels (5).

Description

Heat exchanger with guided air flows

TECHNICAL FIELD

The present invention relates to a heat exchanger that is used in a ventilation system for a building and an assembly housing in a ventilation system comprising a heat exchanger according to the preamble of the independent claims.

BACKGROUND

When outdoor air is coming into a building a heat exchanger is normally used in order to pre heat the incoming air. The heat exchanger is also used to recover the thermal energy in the outgoing air coming from the building and the thermal energy is thus, used to heat the incoming air.

Different kinds of heat exchangers may be used in a ventilation system of a building. One kind of heat exchanger is a plate heat exchanger. In a plate heat exchanger two different air flows, the outgoing air and the incoming air, are guided in two different passages between the plates in the heat exchanger. One commonly known principle guides the two air flows in a cross flow and counter flow circulation. From EP 0 044 561 a heat exchanger that uses a cross flow and counter flow circulation is known. This heat exchanger guides a secondary media flow first in a cross flow circulation in relation to a primary media flow, thereafter in a counter flow circulation and finally, before exiting the heat exchanger again in a cross flow circulation. The secondary media is guided through the heat exchanger by means of partition walls.

This known way of guiding the air flows in a heat exchanger is related to problems. The air flow in the heat exchanger will not have an even velocity and the pressure distribution over the surface of the heat exchanger will be poor. These aspects result in a low efficiency. Thus, there is a need for an improved heat exchanger that eliminates these problems.

SUMMARY

The object of the present invention is to address the problems outlined above. These objects, and others, are achieved by the apparatus according to the appended independent claims. Preferred embodiments are defined by the dependent claims.

According to a first aspect, the invention discloses a heat exchanger. The heat exchanger comprises a plurality of stacked channel plates comprising longitudinal air channels. The plates have a rectangular shape with the air channels arranged between a first and second edge, in which channels an incoming air flow is guided. A plurality of elongated adhesive stripes are arranged adjacent to each other between two adjacent plates in order to attach the plates to each other, and the elongated stripes form the walls of channels wherein an outgoing air flow is guided. The length of the elongated stripes decreases towards the centre of the plate, and the distance between two adjacent elongated stripes decreases towards the centre of the plate.

By arranging the elongated stripes in the above mentioned way an evenly distributed air flow is achieved. This leads to a good heat transfer between the plates, further leading to a heat exchanger with a high efficiency.

The outgoing air flow is guided between two adjacent plates by means of the elongated stripes and a plurality of short spaced apart stripes arranged on both sides of a centre line and perpendicular thereto. The elongated stripes are arranged between the spaced apart stripes and the first and second edge.

The elongated stripes may be arranged perpendicular to a third edge on both sides of the centre line of the plate. Alternatively, the elongated stripes may be parallel and arranged with a smaller or greater angle than 90° in relation to the third edge on both sides of the centre of the plate.

By arranging the elongated and spaced apart stripes in the above mentioned manner the air flows in the heat exchanger will have both a cross flow direction and a counter flow direction, which has the advantage that the heat exchanger will have a higher convection to the material in the plates. Thus, leading to a higher efficiency in the overall temperature transfer and thereby, the amount of material required may be reduced.

The plurality of stacked channel plates may comprise a first plate with the elongated stripes arranged with a smaller angle than 90° and a second adjacent plate with the elongated stripes arranged with a greater angle than 90°. By inclining the elongated stripes in different directions on subsequent plates an evenly distributed outgoing air flow is achieved.

The number of the elongated stripes on each side of the centre of the plate is at least four. This number is a minimum amount for ensuring an even flow distribution. The maximum amount of elongated stripes is limited by the size of the heat exchanger, and thus, the size of the plates.

The heat exchanger is sealed by sealing stripes along the periphery, except where the outgoing air flow is coming into and out of the heat exchanger. By using sealing stripes along the periphery of the plates a tightly sealed housing for the heat exchanger is ensured. This is especially important when no recirculation of used air is allowed, e.g. in hospitals. The heat exchanger assembled according to the invention ensures that the outgoing air flow not is mixed with the incoming air flow.

According to a second aspect, the invention provides an assembly housing in a ventilation system comprising a heat exchanger. The assembly housing of a ventilation system is placed in connection to the building that is to be ventilated. The assembly housing can be arranged indoors or outdoors. In order to achieve an efficient ventilation system, it is advantageously when the heat exchanger is comprised in the assembly housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail, and with reference to the accompanying drawings, in which:

- Figure 1 illustrates a schematically perspective view of the air flows in the heat exchanger;

- Figure 2 shows the air flows in connection to a channel plate; and

- Figure 3 illustrates a side view of a channel plate.

DETAILED DESCRIPTION

In the following description, the invention will be described in more detail with reference to certain embodiments and to the accompanying drawings. For purposes of explanation and not limitation, specific details are set forth, such as particular scenarios, techniques, etc., in order to provide a thorough understanding of the present invention. However, it is apparent to one skilled in the art that the present invention may be practised in other embodiments that depart from these specific details. Figure 1 illustrates an exemplary embodiment of the heat exchanger 1 in a

schematically perspective view. Figure 2 shows the air flows in connection to a channel plate 2. In both figures the air flow going into the heat exchanger, being guided through the heat exchanger and coming out of the heat exchanger are shown. Figure 1 shows the incoming air flow from the open air 10 that passes through the heat exchanger 1 and coming out as the incoming air flow into a building 11. When passing through the heat exchanger 1 the incoming air flow 10, 11 recovers thermal energy from the outgoing air flow 12-14. The outgoing air flow 12-14 coming from inside the building, is guided through the heat exchanger 1 and coming out into the open air.

In figure 2 a channel plate 2 is shown that have elongated channels 5. These parallel longitudinal channels may have a rectangular shape, but other cross sectional shapes of the channels are also possible, e.g. round or oval. As can be seen in figure 2 the incoming air flow 10, 11 is guided through the channels 5 in the plates. In order to efficiently recover the thermal energy in the outgoing air flow 12-14, the outgoing air flow is guided through the heat exchanger in channels 6 between subsequent plates 2 created by elongated stripes (which are further described in figure 3) . The outgoing air flow from a building 12 passes through the heat exchanger, between the channel plates 2. The outgoing air flow from a building 12 is perpendicular to the incoming air flow 10, 11, i.e. has a cross flow direction. Thereafter, the outgoing air flow changes direction by 90° and the outgoing air flow 13 is then parallel to the incoming air flow 10, 11, i.e. has a counter flow direction. Finally, the outgoing air flow 14 changes further direction by 90° and is guided between the channel plates 2, in a direction opposite the outgoing air flow from a building 12. The outgoing air flow to the open air 14 is perpendicular to the incoming air flow 10, 11, i.e. has a cross flow direction. Thus, the outgoing air flow 12-14 is guided through the heat exchanger both in a cross flow and counter flow direction in relation to the incoming air flow 10, 11. In figure 3 a single channel plate 2 is illustrated in a side view. Adhesive stripes comprising elongated stripes 3 and spaced apart stripes 4 are arranged on the plate. The stripes 3, 4 are made of an adhesive material in order for properly attaching the plates 2 to each other. The stripes 3, 4 are arranged between subsequent plates 2 in order to create chambers between adjacent plates for the outgoing air flow 12-14 to pass through. The short spaced apart stripes 4 are evenly distributed over an area around the centre of the plate and are perpendicular to a centre line 8. The short spaced apart stripes 4 have a length that ranges from 3 to 30 mm and are spaced apart with an equal distance or a longer distance, i.e. a distance that at the most is twice as long as each stripe. The elongated stripes 3 may decrease evenly, e.g. with 70 to 90% by each stripe or the decrease may vary between two adjacent stripes and the next thereafter following adjacent stripe 3. The distance between two elongated stripes 3 may also decrease evenly, e.g. with 70 to 90% or the decrease of the distance between two adjacent stripes 3 and the distance between the two thereafter following adjacent stripes 3 may decrease with different amounts. The elongated stripes 3 are distributed over an area that is defined by reaching from first and second edge 20, 21 towards the centre of the plate, to the area where the spaced apart stripes 4 are arranged. The elongated stripes 3 may be perpendicular to the third edge or being inclined with an angle a that is smaller or greater than 90°, e.g. somewhere between 70° and 110°. A smaller angle a than 90° means the elongated stripes 3 being inclined towards the centre of the plate. And a greater angle a than 90° means the elongated stripes 3 being inclined towards the first and second edge 20, 21, respectively. The inclined elongated stripes 3 are also parallel to each other. For ensuring a tightly sealed heat exchanger sealing stripes 7a, 7b are arranged around the periphery of the plate, except where the inlet and the outlet of the outgoing air flow 12- 14 are situated.

The number of plates 2 constitutes the length of the heat exchanger 1. Thus, the number of plates is adapted to the amount of air required for the ventilation system of the building in question. The inclination angle a of the elongated stripes 3 may be the same on each plate. Alternatively, the inclination angle a of the elongated stripes 3 of two adjacent plates may differ, e.g. the angle a of the elongated stripes 3 on one plate being smaller than 90° and the angle a of the elongated stripes 3 on the adjacent plate being greater than 90°. In an alternative embodiment the heat exchanger is arranged within an assembly housing. The assembly housing of a ventilation system is placed in connection to the building that is to be ventilated. An assembly housing is a well known device, therefore it is not illustrated in a drawing. The assembly housing may be arranged indoors or outdoors in connection to the building. The efficiency of temperature is derived from the difference of temperature between incoming air guided from the heat exchanger into the building and incoming air guided to the heat exchanger from the open air. The humidity in the outgoing air from the building is another parameter considered when the efficiency is calculated. The inlet and outlet of outgoing air 12, 14 are arranged on the same third edge 9 in figure 3. In an alternative embodiment they may also be arranged on opposite sides, i.e. one on the third edge and the other on the opposite edge.

The incoming air flow 10, 1 1 from the open air coming into a building is described as passing through the longitudinal channels 5 in the plates 2 and the outgoing air flow 12- 14 passes through channels 6 in between adjacent plates. It is also possible to invert the air flows, i.e. the incoming air flow 10, 11 may be guided between adjacent plates in channels 6 and the outgoing air 12- 14 may be guided within the longitudinal channels 5.

Further, the above mentioned and described embodiments are only given as examples and should not be limited to the present invention. Other solutions, uses, objectives, and functions within the scope of the invention as claimed in the accompanying patent claims should be apparent for the person skilled in the art.

Claims

1. Heat exchanger (1) comprising a plurality of stacked channel plates (2)

comprising longitudinal air channels (5), wherein

- the plates have a rectangular shape with the air channels (5) arranged between a first and second edge (20, 21), in which channels an incoming air flow (10, 1 1) is guided,

characterized in that

- a plurality of elongated adhesive stripes (3) are arranged adjacent to each other between two adjacent plates in order to attach the plates to each other, and in that

- the elongated stripes (3) form the walls of channels (6) wherein an outgoing air flow (12- 14) is guided, wherein

the length of the elongated stripes (3) decreases towards the centre of the plate, and

the distance between two adjacent elongated stripes (3) decreases towards the centre of the plate.

2. Heat exchanger according to claim 1, characterized in that the outgoing air flow (12-14) is guided between two adjacent plates (2) by means of the elongated stripes (3) and a plurality of short spaced apart stripes (4) arranged on both sides of a centre line (8) and perpendicular thereto, and wherein the elongated stripes (3) are arranged between the spaced apart stripes (4) and the first and second edge (20, 21).

3. Heat exchanger according to claim 1 or 2, characterized in that the elongated stripes (3) are arranged perpendicular to a third edge (9) on both sides of the centre line (8) of the plate.

4. Heat exchanger according to claim 1 or 2, characterized in that the elongated stripes (3) are parallel and arranged with a smaller angle (a) than 90° in relation to a third edge (9) on both sides of the centre of the plate, thus, the elongated stripes (3) being inclined towards the centre of the plate.

5. Heat exchanger according to claim 1 or 2, characterized in that the elongated stripes (3) are parallel and arranged with a greater angle (a) than 90° in relation to a third edge (9) on both sides of the centre of the plate, thus, the elongated stripes (3) being inclined towards the first and second edge (20, 21) , respectively.

6. Heat exchanger according to claim 4 and 5, characterized in that the plurality of stacked channel plates (2) comprises a first plate with the elongated stripes (3) arranged with a smaller angle (a) than 90° and a second adjacent plate with the elongated stripes (3) arranged with a greater angle (a) than 90°.

7. Heat exchanger according to any of the preceding claims, characterized in that the number of the elongated stripes (3) on each side of the centre of the plate is at least four.

8. Heat exchanger according to any of the preceding claims, characterized in that the heat exchanger is sealed by sealing stripes (7a, 7b) along the periphery, except where the outgoing air flow (12-14) is coming into and out of the heat exchanger.

9. Assembly housing in a ventilation system comprising a heat exchanger

according to any of the preceding claims.