WO2011040859A1

WO2011040859A1 - Heat exchanger with channel plates

Info

Publication number: WO2011040859A1
Application number: PCT/SE2010/050727
Authority: WO
Inventors: Erik Helmenius
Original assignee: Ny Kraft Sverige Ab
Priority date: 2009-09-30
Filing date: 2010-06-24
Publication date: 2011-04-07
Also published as: EP2483010A4; EP2483010A1; SE534657C2; SE0901253A1

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, wherein the plates are channel plates (2) comprising longitudinal air channels (5), the adhesive stripes (3, 4) are arranged perpendicular to the channels in the plates, and the outgoing air flow (12, 14) is perpendicular to the incoming air flow (10, 11). The adhesive stripes comprise a polymer adhesive.

Description

Heat exchanger with channel plates

TECHNICAL FIELD

The present invention relates to a heat exchanger that is used in a ventilation system for a building. The heat exchanger comprises a plurality of parallel plates assembled by stripes of an adhesive. The invention furthermore relates to an assembly housing in a ventilation system comprising a heat exchanger and a method of manufacturing a heat exchanger. 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 circulation.

From WO 97/ 19310 a heat exchanger that uses a cross flow circulation by means of corrugated plastic elements is known. The extract air coming from the building is guided between two adjacent elements and input air passes through channels formed in each element. The elements are joined together to form a pack of elements with the aid of durable packing strips. The material of the strips is not further specified in this document.

One commonly known way of assembling plates in a heat exchanger uses a foam based adhesive tape that is a two component material. However, use of this sort of tape is related to many problems. Firstly, when there are changes in the outdoor temperature the tape expands or decreases, which leads to considerable variations in the overall size of the heat exchanger. Secondly, after some time the tape may not adhere properly to the plates. Thirdly, the tape does not sufficiently seal the heat exchanger, i.e. the material of the tape is not creating a tight sealing between the plates. Fourthly, the tape must be applied manually and makes thus, the manufacturing a time consuming process.

This known way of assembling the plates in a heat exchanger is therefore, related to among others the above mentioned problems. Thus, there is a need for an improved heat exchanger that eliminates the described problems. SUMMARY

The object of the present invention is to address the problems outlined above. These objects, and others, are achieved by the apparatus and the method according to the appended independent claims. According to a first aspect, the invention provides a heat exchanger. The heat exchanger comprises a plurality of parallel plates assembled by stripes of an adhesive. The plates are plastic channel plates comprising longitudinal air channels and the adhesive stripes are arranged perpendicular to the channels in the plates. The outgoing air flow is perpendicular to the incoming air flow. The adhesive stripes comprise a polymer adhesive.

By arranging the adhesive stripes perpendicular to the longitudinal channels in the plates a cross flow circulation is achieved for the two air flows, one outgoing air flow and one incoming air flow. By using adhesive stripes comprising a polymer adhesive a stable and durable heat exchanger is achieved. The stripes comprising a polymer adhesive will only expand or decrease very little when exposed to temperature variations. Therefore, the size of the heat exchanger will substantially remain constant when the outdoor temperature is changing, which is an important advantage.

Using a polymer adhesive is also advantageously since it ensures a tightly sealed housing for the heat exchanger. This is especially important when no recirculation of used air is allowed, e.g. in hospitals. The heat exchanger assembled with adhesive stripes of polymer ensures that the outgoing air flow not is mixed with the incoming air flow.

A further advantage when adhesive stripes comprising polymer are used is that the material comprising a polymer is sound-absorbing. Thus, the heat exchanger does not necessitate further sound-absorbing material in connection to the outer housing. This makes the heat exchanger appropriate to be arranged in an outdoor assembly as well as in an indoor assembly. In a preferred embodiment of the invention the polymer adhesive comprises a MS-polymer or a hybrid polymer. These materials are one component

materials. They have amongst other the following advantages; being

environmental friendly, they do not require a pre treatment of the surface to which the adhesive stripes are to be applied to ensure sufficient bounding strength and the use of a primer can be avoided.

In one embodiment of the invention the channels in the channel plates have a rectangular cross section. This cross sectional shape simplifies the

manufacturing of the channel plates.

In one embodiment of the invention the adhesive is applied in longitudinal stripes perpendicular to the channels in the channel plates. To efficiently recover the thermal energy in the outgoing air flow, the outgoing air flow is guided twice through two different chambers in the heat exchanger. The longitudinal stripes ensure a tightly sealed heat exchanger, divided into the two chambers.

In one embodiment the adhesive is also applied with intermittent stripes perpendicular to the channels in the channel plates. Since these stripes are evenly distributed over the surface of a plate, i.e. evenly between two adjacent plates, they help to create a stable heat exchanger. The intermittent stripes also enhance the guiding of the outgoing air flow. The plates are arranged at a distance between two subsequent plates that ranges from 2 to 4 mm, preferably 3 mm. The dimensions of the heat

exchanger may be expressed as a ratio between height and width. This ratio is typically 1 :2. This is an optimum distance and an optimum ratio of the dimensions in order to achieving a high efficiency of the heat exchanger.

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.

According to a third aspect, the invention provides a method of manufacturing a heat exchanger. The method comprises the steps: placing a channel plate in an applicator machine, fixing the plate in the machine by using under pressure, applying stripes of an adhesive on the channel plate by means of an applicator head, applying stripes of the adhesive perpendicular to the channels in the plate and assembling the channel plates parallel to each other. Thus, the heat exchanger is manufactured in an efficient way by means of a machine and the manufacturing steps necessary to be performed manually are reduced. In this way the costs of production are limited, which consequently is an

advantage of the invention. In one embodiment the method of manufacturing comprises arranging at least one support device between two adjacent plates when the plates are assembled and removing the support device after the stripes of adhesive have cured. This has the advantage that the plates are arranged at a fixed, specific distance, i.e. not vary between two adjacent plates and not vary between different plates within the heat exchanger. 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 is a perspective view of the heat exchanger;

- Figure 3 shows one channel plate of the heat exchanger; and

- Figure 4 is an overview of the machine in which the heat exchanger is

manufactured.

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 heat exchanger 1 in a slightly different perspective view, with assembled channel plates. In both figures the air flows 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

1 1. When passing through the heat exchanger 1 the incoming air flow 10, 1 1 recovers thermal energy from the outgoing air flow 12, 14. The outgoing air flow passes twice through the heat exchanger 1 , where the outgoing air flow

12, 14 is perpendicular to the incoming air flow 10, 1 1.

In figure 2 channel plates 2 are shown that have longitudinal channels 5. Between two adjacent channel plates 2 longitudinal adhesive stripes 3 are arranged. The incoming air flow from the open air 10 is guided through the channels 5 in the plates and continues as the incoming air flow into a building

1 1. In order to efficiently recover the thermal energy in the outgoing air flow 12, 14, the air flow is guided twice through the heat exchanger in chambers between subsequent plates 2 created by longitudinal stripes 3. The outgoing air flow from a building 12 passes a first time through the heat exchanger, between the channel plates 2. Thereafter, the outgoing air flow changes direction with 180° in a chamber 7. The air flow that changes direction 13 is guided back through the heat exchanger a second time, passing between the channel plates 2, in a direction opposite the outgoing air flow from a building

12, and comes out as the outgoing air flow to the open air 14.

In figure 2 a partition wall 6 is shown arranged between the outgoing air flow from a building 12 and the outgoing air flow to the open air 14. The partition wall 6 is arranged perpendicular to the plates 2 in the longitudinal extension of longitudinal stripes 3 in order to further guide the outgoing air flow 12, 14. The longitudinal stripes 3 are arranged between subsequent plates 2 in order to create the chambers for the outgoing air flow 12, 14 to pass between the plates 2.

The dimensions of the heat exchanger may be expressed as a ratio between height and width, preferably the ratio is around 1 :2. But the ratio of the dimensions may also differ. The length of the heat exchanger is adapted to the size of the building at which the heat exchanger is to be installed. 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. In figure 3 a single channel plate 2 is illustrated. The channel plate comprises a number of parallel longitudinal channels 5 having a rectangular cross section. Other cross sectional shapes of the channels are also possible, e.g. round or oval. Adhesive stripes comprising longitudinal stripes 3 and intermittent stripes 4 are arranged on the plate, perpendicular to the channels. The adhesive stripes comprise a polymer, preferably the stripes comprise a MS- polymer adhesive or a hybrid polymer adhesive. Other materials comprising polymers may also be used.

The channel plates 2 are manufactured in any appropriate light weight material such as plastic or aluminium. The plastic material comprises e.g. polycarbonate or polypropylene. The plates may be manufactured in only one material or in a mixture of different materials.

The heat exchanger may be 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 in the heat exchanger 1 at normal air flow rate is at least 90%. The efficiency of temperature is derived from the difference of temperature between incoming air guided 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.

Figure 4 illustrates an applicator machine, in which a channel plate 2 is arranged. In the shown machine the channel plate is arranged horizontally.

The plate may also be arranged differently. The channel plate is fixed on a plan surface by using under pressure by means of openings 20 in the plan surface. An applicator head 21 is guided by a X-Y cradle 22. The applicator head 21 applies stripes of adhesive on the channel plate in a pattern that e.g. is programmed in a computer. The adhesive is applied in longitudinal stripes 3 and in intermittent stripes 4. The channel plates are assembled parallel. The number of plates constitutes the length of the heat exchanger, which length is adapted to the size of the building, the amounts of air required for ventilation etc. When assembling the channel plates a support device or a plurality of support devices are normally used in order to fix the distance between two adjacent plates until the adhesive stripes 3, 4 have cured. The distance between two subsequent plates ranges from 2 to 4 mm, preferably it is 3 mm.

The manufacturing of the heat exchanger is preferably done in an indoor environment having a temperature of around 18 to 20 °C, and a relative humidity of about 40-60%. When applying the adhesive and assembling the plates by means of the adhesive it is important that the adhesive has the appropriate indoor temperature. 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 parallel plates assembled by stripes of an adhesive, wherein

- the plates are channel plates (2) comprising longitudinal air channels (5),

- the adhesive stripes (3, 4) are arranged perpendicular to the channels in the plates, and

- the outgoing air flow (12, 14) is perpendicular to the incoming air flow (10, 1 1),

characterized in that

the adhesive stripes comprise a polymer adhesive.

2. Heat exchanger according to claim 1 , characterized in that the stripes comprise a MS-polymer adhesive or a hybrid polymer adhesive.

3. Heat exchanger according to claim 1 , characterized in that the channels (5) in the channel plates (2) have a rectangular cross section.

4. Heat exchanger according to claim 1 or 2, characterized in that the

adhesive stripes comprise longitudinal stripes (3).

5. Heat exchanger according to claim 1 or 2, characterized in that the

adhesive stripes comprise intermittent stripes (4).

6. Heat exchanger according to any of the preceding claims, characterized in that the plates are arranged at a distance between two subsequent plates that ranges from 2 to 4 mm.

7. Heat exchanger according to any of the preceding claims, characterized in that the dimensions of the heat exchanger has a ratio between height and width that is 1 :2.

8. Assembly housing in a ventilation system comprising a heat exchanger according to any of the preceding claims. Method of manufacturing a heat exchanger wherein the method comprises

- placing a channel plate (2) in an applicator machine,

- fixing the plate in the machine by using under pressure,

- applying stripes of an adhesive on the channel plate by means of an applicator head (21),

- applying stripes of the adhesive perpendicular to the channels (5) in the plate (2) and

- assembling the channel plates parallel to each other.

Method according to claim 9 wherein the method further comprises arranging at least one support device between two adjacent plates when assembling the plates, and removing the support device after the stripes of adhesive have cured.