TECHNICAL FIELD

The present invention relates to a heat exchange device for transfer of heat energy between a first and a second fluid.

PRIOR ART

Within the technology, there are several prior art methods and devices for passive heat transfer, which are powered by a temperature difference between two or several fluids. A plate heat exchanger is a common such device, which comprises a set of plates adapted to form two separate channels for two fluid flows, where each channel is formed between every second pair of plates, and which allows for a transfer of heat or cooling through the plates in the direction of their thickness. The plates are normally very thin, in order to allow for an efficient heat transfer, and in some cases may even be equipped with surface enlargements, such as dents or nano-particles, to increase the contact area with the fluids. Plate heat exchangers are usually considered to be the best alternative in fluid-to-fluid- applications. Regarding fluid-to-air applications, it is prior art to weld a number of flanges onto a pipe, where the fluid flows inside the pipe and the enlarged surface area with the flanges interacts with the ambient air or gas.

One area of application for heat exchangers is in ventilation systems for buildings, in which indoor air is replaced with outdoor air. By arranging a heat exchanger between outgoing and incoming air flows, the temperature of the incoming air flow will be brought closer to the indoor temperature, which results in a passive heating and/or cooling with the objective of avoiding costs. A common form of heat exchanger for ventilation systems uses a liquid carrier to transport thermal energy from one ventilation flow to another. SUMMARY OF THE INVENTION

One objective of the present invention is to specify a new form of heat exchanger, which is cheap to manufacture, has low operating costs and is reliable.

According to a first aspect of the invention, at least one of these objectives is achieved with the heat exchange device according to the preamble of claim 1, which device further is arranged in accordance with the characterising portion of said claim.

The heat exchanger according to the present invention differs from existing heat exchangers in that the heat constituting accumulator plates pass through every fluid chamber and may be located at a very small distance from each other. This means that, thanks to the present invention, it is possible to fit a significantly larger number accumulator plates, for example ten, in the same area in which only a single accumulator plate could be fitted according to prior art, and thus the new technology has, in such an embodiment, ten times the heat transfer capacity of prior art technology in the same area, which accordingly results in a significantly higher efficiency.

Thus, a good heat exchange device is obtained, with good heat transfer properties and accordingly a high degree of efficiency, and which provides a very large accumulator area for heat transfer between a first fluid chamber and a second fluid chamber and vice versa. Since the plate elements comprise at least two ridges, a plurality of fluid chambers may be formed at a short distance from each other, which improves the heat transfer between them and facilitates the placement of the plate elements at a very short distance from each other.

According to one aspect of the present invention, the ridges comprise a recessed part and a protruding part, wherein the protruding part of the ridge in a plate element is shaped so that it fits into the recessed part of the ridge in an adjacent plate element, and the ridges also comprise a bending angle of at least 45°, preferably at least 55°, and more preferably at least 65°. Thanks to the bending angle, it is possible to control the distance between adjacent plate elements so that a greater bending angle entails a shorter distance without resorting to conventional fixation methods such as soldering, welding or screw

connections. Accordingly, the accumulator surface of the heat exchange device may be increased drastically compared to prior art heat exchangers, while the assembly of the device remains simple, cheap and fast. In this regard, the distance between two adjacent plate elements is less than 0.5 mm, preferably less than 0.2 mm, and more preferably less than 0.1 mm, which results in a very large accumulator surface and a high degree of efficiency. The transport distance of the heat energy through the ridges is significantly shorter than in similar, prior art constructions, which also results in a higher effectiveness and degree of efficiency of the technology according to the present invention.

According to another aspect of the present invention, the heat exchange device comprises a control plate with a plurality of control elements arranged to control the flow of a first fluid to or from the first fluid chambers and to control the flow of a second fluid to or from the second fluid chambers. Thus, the flow of a first fluid may be controlled from a delivery device to a plurality of first fluid chambers that are located at a distance from each other, and which subsequently, following passage through the heat exchange device, meet in a joint outflow conduit, and accordingly a high degree of efficiency and good effectiveness may be obtained without any risk of the two flows of fluid mixing.

According to another aspect of the invention, said control device comprises a plurality of openings in the control plate. Thus, the advantage described above may be obtained in a simple and cheap way, but still with a high degree of reliability and low risk of mixing the airflows.

Additional advantages of the invention are described in the detailed description below, and will be easily perceived by a person skilled in the art. DRAWINGS

The invention is described in detail below with reference to the enclosed drawings.

Fig. 1 shows a perspective view of a plate element according to one preferred embodiment of the heat exchange device according to the present invention;

Fig. 2 shows a side view of a ridge in the plate element in Fig. 1;

Fig. 3 shows a perspective view of a plurality of plate elements according to the preferred embodiment from Fig. 1;

Fig. 4 shows a side view of the plate elements in Fig. 3 when these are stacked on each other; Fig. 5 shows a perspective view of a heat exchange device according to the preferred embodiment of the present invention with a cover enclosing a stack of plate elements; and

Fig. 6 shows an exploded view of the heat exchange device in Fig. 5 together with flanges for incoming and outgoing air and a control plate to control the airflows to and from the flanges, respectively.

DETAILED DESCRIPTION Fig. 1 shows a plate element 1 according to one preferred embodiment of the present invention. The plate element 1 comprises an essentially rectangular plate, made of for example aluminium, which includes at least two ridges 2 made by bending, pressing or similar. The ridges 2 are extended essentially in parallel with an edge of the plate element 1 and are arranged essentially in parallel to each other. Fig. 1 shows a plate element 1 with three ridges 2, but the number may vary from two and upwards as will be explained below.

Fig. 2 shows the plate element 1 from the side, with a ridge 2 comprising a protruding part 2a and a recessed part 2b. In this example the width bi of the ridge is 2 mm and the recessed part 2b's width b2 is 0.7 mm and the height of the ridge is 2 mm. The thickness of the plate element is 0.15 mm, and regarding this plate element 1 , the distance between two ridges is approximately 10 mm. It should be pointed out that these figures are specified only as an example in connection with this preferred embodiment and that the plate element 1 according to the invention obviously may have different dimensions without diverging from the invention as defined in the enclosed claims. Depending on the thickness of the plate elements, different dimensions may achieve different advantageous embodiments, and for plate elements made of very thin plate, a very short distance between ridges, in the range of 5-8 mm, may provide a high degree of efficiency and good effectiveness. Furthermore, the ridge 2 has a bending angle a that determines the distance between adjacent plate elements 1 when these are stacked together. In general, the greater than bending angle, the shorter the distance between adjacent plate elements 1. The bending angle a is thus at least 45°, preferably at least 55°, more preferably at least 65°. In this example embodiment a bending angle of approximately 65° would entail that the distance between adjacent plate elements 1 is approximately 0.2 mm, and that, regarding plate elements with this thickness, 30 plate elements per 1 centimetre thus may be stacked, entailing a very large accumulator area in the heat exchanger.

Fig. 3 shows a plurality of plate elements 1 put together vertically, so that the ridges 2 of one plate element face the corresponding ridges 2 of the adjacent plate element 1. Thus, the shape of the ridges is such that the recessed part 2b of a ridge 2 fits into the protruding part 2a of the corresponding ridge 2 in the adjacent plate element 1. When the plate elements are stacked on top of each other, the ridges 2 will be pressed together so that they abut each other, as displayed in Fig. 4, and the ridges 2 will jointly form a wall 3 defining two fluid chambers (see Fig. 5-6). The wall 3 thus forms a thermally conductive and airtight delimitation, which means heat energy may be transferred from one fluid chamber to the adjacent fluid chamber.

Thanks to the shape of the ridges 2 and the stacking of the plate elements 1 on each other, the plate elements 1 are very simple and cheap to manufacture, for example with an eccentric press, and fluid chambers may be formed and separated from each other without having to attach plate elements 1 to each other in any way other than solely by way of stacking. This is a great advantage of the invention, since the assembly of a plate heat exchanger is otherwise a very time consuming task and it may be difficult to achieve a large accumulator area, i.e. to assemble plate elements at a short distance from each other. Since the distance may be kept constant throughout the entire stack and the plate elements 1 are kept in place by gravity and friction between the plate elements 1 , a very cheap and effective heat exchanger with a high degree of efficiency is obtained, which is quick and easy to assemble. Since a plurality of ridges 2 are provided in each plate element 1, a plurality of fluid chambers may thus be formed, which also contributes to an increased degree of efficiency and simplifies the fixation of the plate elements 1 against each other. In another embodiment, the ridges 2 may be adapted in a different manner, for example by attaching a metal wire along the plate element 1 at the location of the ridge 2. The plate elements 1 may thus be stacked without fitting a protruding part into a recessed part, but simply by way of the height of the elevated ridges which are formed through an elongated object being placed on the surface of the plate element and providing the distance between two plate elements 1 in a stack.

A large number of ridges, as displayed in Fig. 3, provides a large number of fluid chambers 4, 5 at a short distance from each other and thus improves the heat exchange between the two fluids. However, it should be noted that the number of ridges may vary depending on the application, and that a lower number may also result in a good effectiveness and satisfactory degree of efficiency. Fig. 5 shows a heat exchange device 10 with a cover 11, which has a first end 12 and a second end 13 and which encloses a plurality of plate elements 1 arranged in a stack as described above. The ridges 2 form walls 3 that run along a flow direction F and define a plurality of fluid chambers, namely in this embodiment 15 first fluid chambers 4 and 15 second fluid chambers 5. The first fluid chambers 4 are arranged so that a first fluid flows through them, while the second fluid chambers 5 are arranged so that a second fluid flows through them. In this example embodiment, there are 29 ridges 2 in each plate element 1 , and each first or second fluid chamber 4, 5 is defined either by two adjacent ridges 2 forming walls 3 or by one ridge 2 and one outer edge of the plate element 1. In a preferred embodiment where there are only two ridges 2, a first fluid chamber 4 and two second fluid chambers 5 are instead formed, or vice versa, and in another embodiment obviously there may be a greater or smaller number of ridges 2 in each plate element 1.

When the heat exchange device is used in, for example, a ventilation system, the first fluid may, for example, be heated air from inside a building, and the second fluid may be colder air from outside of the building.

Fig. 6 shows the heat exchange device 10 jointly with additional components that may be assembled together to move the first fluids to and from the heat exchange device 10 on one side of said device. It is advantageous also to assemble corresponding components on the other side, in the flow direction, to move the fluids to and from this side as well.

The first and second fluid chambers 4, 5 are thus extended by way of providing a framework 6, which also forms air channels and simplifies the movement of the first and second fluids to and from a supply device and an outflow device in the form of flanges 8a, 8b. In order to move the first fluid between the first fluid chambers 4 and the supply device in the form of an upper flange 8a and the second fluid between the second fluid chambers 5 and an outflow device in the form of a lower flange 8b, there is also a control plate 7 with control elements 71, preferably in the form of openings 71 preventing fluids from coming into contact with the wrong flange. The control plate 7 operates as an air distributor, controlling incoming and outgoing air flows to and from the atmospheric air and to and from indoor air in two closed systems, which means the outbound, used air cannot come into contact with the inbound, fresh air. The supply device 8a and the outflow device 8b may obviously be adapted differently than by way of flanges, and the control elements 71 may have a different design than as openings in a control plate 7, for example as conduits with nozzles or similar. In a different embodiment, the supply device and/or the outflow device may also comprise a plurality of nozzles and conduits providing input or exhaust air in a plurality of places. The invention is not limited to the examples and embodiments displayed but may be varied freely in the framework of the claims below. For example, the ridges of the plate elements may be adapted in various ways and the components around the heat exchanger may be designed in different ways, as long as they move a first and a second fluid to and from the fluid chambers in the heat exchanger. Furthermore, features which are displayed exclusively for an example or an embodiment in the description may as well be used in different embodiments and examples.