SE538217C2 - Heat exchangers and ventilation units including this - Google Patents

Abstract

SUMMARY A heat exchanger comprises two sets of adjacent heat exchangers between a first and a second air stream. Each of the up ducts (5, 6) comprises at least one transverse drainage channel (4) for battle (condensation. A ventilation unit comprises such a heat exchanger.

Description

TECHNICAL FIELD The present invention relates to a heat exchanger comprising two sets of adjacent heat exchange channels between a first and a second air stream. The invention also relates to a ventilation unit.

AGE TECHNOLOGY In order to achieve maximum heat theater gain from outgoing room air, balanced heat exchangers with parallel vertically arranged plates, for example made of thin plastic or aluminum, and where the heat exchanging surface is maximized by designing plates with channels with outgoing room air (exhaust air) and incoming outdoor air (supply air) in countercurrent. A common geometry is plate thickness 0.1-0.5 mm, distance between the plates 1.5-5 mm and channel width (channel height) 2-5 mm.

When the outdoor temperature is considerably lower than the room temperature, the humidity of the room air condenses in the exhaust air ducts of the heat exchanger and sometimes causes blockages of water droplets leading to an increase in the air resistance on the exhaust air side of the heat exchanger. At outdoor temperatures below -2 ° to -4 ° C, the condensate in the heat exchanger's room air ducts freezes so that efficiency-enhancing conditions such as the introduction of electric auxiliary heat into the heat exchanger must be used.

In absolute terms (g water / kg air), the outdoor air in winter contains very little moisture, which means that the indoor climate becomes dry. A humidification of the heated supply air lowers its temperature. which means either an excessively low supply temperature with the supply of evaporation heat from the room air or that the supply air must be reheated before supply to the room. The problem of and & ton air in winter is solved with advantage by integrating an aerosol generator for increasing the moisture content of the supply air into the construction with the technology described in the Swedish patent SE 534398 C2. 1 In summer, when cooling needs are sometimes present, the heat exchanger can provide an undesirable heating of the supply air, by heat transfer from hot exhaust air, which is heated by people and equipment indoors. A common solution to this problem is to arrange a thermostatically or manually operated bypass duct for the exhaust air internally in the ventilation unit, or as an extension to the unit. However, this results in a more complicated and thus more bulky and more costly construction, while the need to occasionally cool the supply air, if the temperature outside is high, remains. In addition, in certain temperature and humidity conditions, water droplets can become clogged on the supply air side of the heat exchanger, with a consequent increase in air resistance.

TROUBLESHOOTING It is thus desired to provide a heat exchanger and a ventilation unit which lack the above-mentioned disadvantages, not least with regard to the undesired increases in air resistance.

TROUBLESHOOTING The grinding seal underlying the invention is achieved by a heat exchanger as defined in appended claim 1.

Additional advantages are obtained if the heat exchanger is further characterized by one or more of the features according to claims 2-4.

Regarding the ventilation unit, the grinding is achieved if this comprises a heat exchanger as above, and further advantages are obtained if it can also be characterized by one or more of the features according to claims 6-8.

COMPILATION OF DRAWING FIGURES The invention will now be described with reference to the accompanying drawings. these show: Fig. 1A is a partially cut-away perspective view of a heat exchanger according to an embodiment of the invention; Fig. 1B is a view corresponding to that of Fig. 1A of a second embodiment of the heat exchanger according to the invention; Fig. 2 is a sectional view along a horizontal plane through a portion of the heat exchanger; Fig. 3A is a partially cut-away plan view of the heat exchanger according to the invention; Fig. 3B is a view corresponding to that of Fig. 3A of a detail of the heat exchanger; and Fig. 4 is a schematic diagram of a ventilation unit according to the invention.

PREFERRED EMBODIMENT Fig. 1A shows a first embodiment of a heat exchanger 25, which comprises a number of pleated plates 1, which are mounted between smooth plates 2. The pleated plates 1 can in principle also consist of a stone number of thin slats, which are arranged at an angle against each other, to build up the pleated structure. As a result, two sets of adjacent ducts 5, 6 are formed for outgoing room air (exhaust air) and incoming outdoor air (supply air), respectively.

The pleated plate 1 has, in a preferred embodiment of the invention, at least one plate 26, which forms drainage channels 4 for condensed water, one on each side of the plate 26, for the two sets of channels 5, 6. The drain channels 4 may have varying designs, which have in common that the two sets of ducts 5, 6 remain closed in relation to each other, so that the two air streams with exhaust air and supply air, respectively, are not mixed. The purpose of the drainage channels 4 is that condensed moisture from the respective air stream is to be led from the channels 5, 6 to the respective drainage channel 4, and flow to a collecting vessel 19. The drainage channels 4 are therefore advantageously upright, preferably approximately vertical, while the channels 5, 6 preferably form an angle to a horizontal plane, so that droplets of condensed moisture in the channels 5, 6 phase to flow in the direction of one of the drainage channels 4. of the other cradles in the drainage channel 4, and finally led down into a collecting vessel 19 (see Fig. 4). Condensation falls out both in contact with the cradles of the channels 5, 6 and in contact with the cradles of the drainage channel 4, but regardless of where the condensation takes place, they must be led to the collecting vessel 19.

Fig. 1B shows a second embodiment of the invention with plates 1 with folds or depressions mounted so that adjacent channels 5 for outgoing room air and 6 for incoming outdoor air are formed between the plates. The plates 1 shown in accordance with the invention also have flats 4 which form vertical drainage channels for condensed water. The pleated plate, or plates, 1 are surrounded by outer, smooth plates 2, which are not shown in Fig. 1B.

Fig. 2 shows a section in a horizontal plane through the area around the flattening 4 and shows how the room air (exhaust air) 5A and incoming outdoor air (supply air) 6A in countercurrent are led on each side of the flattened part 26 of the heat exchanger plate 1. For the sake of clarity it should be clarified the two air streams 5A, 6A are slightly offset in relation to each other in a direction perpendicular to the plane of the drawing, and that they are separated, so that the air streams 5A, 6A do not mix with each other. On this salt, an efficient transport of two air volumes takes place, so that an exchange of the air in the ventilated space takes place.

On the other hand, a transfer of heat can take place from one air stream 5A to the other 6A, through the thin cradles of the pleated plate 1, which are made of such a material and with such a thickness that heat transfer is favored.

Fig. 3A shows a plan view of the room air side (exhaust air side) of a heat exchanger plate 1. The upper and lower edges 8, 27 of the plate 1 and the channels 5, 6 form an angle α relative to 4 a horizontal plane, so that condensation in the channels 5, 6 under the influence of gravity phase to flow in the direction of the flattened parts 26, which enter the drainage channels 4A, 4B and 4C. At its upper edge 8, all heat exchanger plates 1 are tapered towards the surroundings. In the lower edge 27 there is on the room air side a water collecting duct 9 with an outlet opening 10 between the plates, and on the supply air side there is a corresponding water collecting duct 11 with an outlet opening 12 between the plates 1. The outlet openings 10 and 12 are connected to transverse collecting ducts 13 and 14. The condensate flows down a water collection channel 9 at the lower edge 27 of the plate 1 and finally out through a channel 13.

Fig. 3B shows a corresponding detail of the supply air side, with a water collection duct 11 and a duct 14, which are separated from the corresponding details on the outside air side, in order to ensure that the air streams 5A, 6A do not mix with each other.

With it, the proposed design of the heat exchanger plates has the condensed water of the room air removed from the air ducts before the water reaches zones with a risk of freezing.

The heat exchanger plates 1 have been wholly or partly given a hydrophobic surface structure, which facilitates the drainage, by reducing the adhesion of the condensed water to the surfaces, and thus droplets being formed more easily. The surface of the condensate water towards the ambient air also decreases, and the risk of the condensate water evaporating again decreases, which in turn leads to a more efficient dehumidification of the air streams 5A, 6A, which move through the heat exchanger. In addition, the heat exchanger has been designed with one or more vertical drainage channels 4, for draining the condensed water. In this way, the need for additional heat in the heat exchanger can be completely or partially avoided and the overall efficiency of the heat exchanger will be higher.

The hydrophobic surface structure is possible to achieve on a variety of salts. A salt is to give the surface a nanostructure, by coating the surfaces with a suitable agent. For plastic surfaces, it may be an agent that contains silicon compounds so that silicon crystals are formed, which tap into microscopic pores that may be present in the surface of a plastic material. Another salt to create a nanostructure is to emboss it in the surface during the manufacture of the channels 4, 5, 6 cradles.

Fig. 4 shows a cross section (principle view) of a ventilation unit 28 according to the invention, where heat exchanger plates 1 as above. The room air (exhaust air) 5A is filtered in the filter 15 and the incoming outdoor air (supply air) in the filter 16.

Condensate water from the exhaust air 5A is collected in the duct 13 and any condensate from the outdoor air 6A (in hot, humid outdoor climate) is collected in the duct 14. From the ducts 13 and 14 condensate water is led down via pipes or hoses 17, 18 so far below the surface in a water tank 19 that air flooding between the rudders 17 and 18 is prevented. The container 19 is assembled with a water container 20 used in arranged piezoelectric ultrasonic generators 21 and 22, which in the preferred embodiment are two in number. The ultrasonic generators 21 and 22 can be operated individually (50% capacity) or run together (100% capacity). The water aerosol formed in the collector 23 can, in accordance with the Swedish patent SE 534398 C2, be led to the heat air inlet 29 of the heat exchanger 25 between the heat exchanger 25 and a filter 16, where the aerosol is transported into the heat exchanger 25 by means of the cold air stream 6A. that they can be evaporated (evaporated) with the help of heat from the exhaust air 5A.

In the ventilation unit 28 according to the invention, an evaporative cooling of the exhaust air 5A is also optionally used, by supplying a water aerosol to the exhaust air 5A between the heat exchanger 25 and a filter 15. This has the purpose of providing a heat dissipation from excessively hot supply air 6A, e.g. during the summer months. In addition to the temperature of the supply air 6A being lowered, its humidity can also be lowered by condensation falling out at the inner surfaces of the ducts 6 and being led out of the heat exchanger 25 and down into the collecting container 19, in the manner described above.

The aerosol from the ultrasonic generators 21 and 22 is led by repositioning a control valve 24 to the exhaust air intake 30, so that it evaporates and thereby cools down the exhaust air 5A flowing into the heat exchanger 25. With a ventilation unit 28 according to the invention, the problem of excessively dry air in winter is avoided by integrating the ultrasonic generators 21, 22, which provide an aerosol for humidifying the supply air 6A, into the construction with the technology described in Swedish patent SE 534398 C2.

The novelty of the ventilation unit 28 according to the invention is that the ultrasonic generators 21, 22 also have am / ands for evaporative cooling of the exhaust air 5A with the evaporating heat taken from the condensing heat of the exhaust air. Condensation in the channels 5,6 is led out to the drainage channels 4, and clogging of the channels due to water droplets, or freezing of the condensation in the channels 5, 6 is thereby prevented.

In a connection part 7A, the room air (exhaust air) 5A coming to the heat exchanger 25 is distributed over all the channels of the exchanger plate 1 on its front side to be led out via these to the opposite connection part 7B. The incoming outdoor air (supply air) 6A is distributed to the ducts on the rear side of the plate and is led out into the connection part 7A. The connection parts 7A, 7B are designed such that room air 5A and outflowing outdoor air 6A flowing into the heat exchanger 25 exchanges heat in transverse flow as well as the outflowing room air 5A and the flowing outdoor air 6A.

If condensate has formed in the room air ducts 5, this flows down onto the flattened portion 26 of the heat exchanger plate 1 and will thus not be transported further to colder parts of the heat exchanger plate. If continued condensation takes place during the further transport of room air towards the connecting part 7B, this condensed water can be drained in more drainage channels 4B and 4C, closer to the outlet of the room air. If condensation takes place on the supply air side of the heat exchanger plates 1, this condensed water can be drained in a corresponding manner.

The condensate in the ducts 4 can flow freely on the room air side through the opening 10 down into the transverse collecting duct 13. In summer, during evaporative cooling of the exhaust air 5A, moisture in incoming outdoor air 6A can condense on the supply air side of the heat exchanger plates 1 and flow out through the opening 12, in the transverse collection channel 14. 7 The diversion of condensed water down into the channels 4 is facilitated if the surface of the heat exchanger plate 1, especially at the channels 4, has hydrophobic properties, for example with the help of nanotechnology, as discussed above. Faster and more complete drainage of condensation water from all the air ducts 5, 6 of the heat exchanger plate 1 is omitted if the entire heat exchanger plate 1 has corresponding hydrophobic properties. Experiments have shown that the run-off from the heat exchanger plates 1 can be further improved if the plates 1 can be vibrated with aerodynamic or mechanical aids. 8

Claims (7)

PATENT REQUIREMENTS Heat exchangers for heat exchange in countercurrent between a first and a second air stream in two adjacent arrangements of channels (5, 6), formed between vertically arranged pleated plates (1) or between vertically arranged pleated (1) and flat plates (2 ), each set of channels (5, 6) for the air drums forming an angle of 0-30 ° to the horizontal plane, drawn by aft and each of the sets of channels (5, 6) comprising at least one substantially vertical drainage channel (4), formed by a flattening (26) of a pleated plate (1), for dissipating condensation. Heat exchanger according to claim 1, characterized in that the channels (4, 5, 6) have inner surfaces with a hydrophobic surface layer. Heat exchanger according to claim 2, characterized in that the surface layer has a nanostructure. Heat exchanger according to one of Claims 1 to 3, characterized in that the drainage channels (4) are connected to a collecting vessel (19). Ventilation unit comprising a heat exchanger according to any one of claims 1-4. Ventilation unit according to claim 5, characterized in that the first and second air streams are supply air and exhaust air, respectively, and that means are provided for evaporative cooling of the exhaust air (5A) before it is forced into the ducts (5) of the heat exchanger. Ventilation unit according to claim 5 or claim 6, characterized in that means are provided for switching between evaporative cooling of the supply air (6A) and the exhaust air (5A), respectively. Ventilation unit according to Claim 6 or 7, characterized in that a mist generator (21, 22) is provided for effecting the evaporative cooling. 9 1/4 Lo C \ 1 97, -6! A 3/4 L3 Li 4A ..4 ... ,, ,,, .... „. _, __. ,, ■ ■ V-1 ■ ,,,,, ... 4 atgrea, __ ,,, ', .._...__....... 74 z .. ,,, _..._,., 1. .., 7 ,. x ■ ...__. - .... + ..._ 4ra. ,, 7, __ .. r.,. * ....___...... ,,,, „+ - .. w, m7 4B 4C8 7B 6A t Ar ■. 4 '. ■ ••• ftlftwA' 1. ■■■■,. ,, 47. 7. 11. 5A 27 13 4/4 1111111111111111111111KM 4411 11141 11 '0 1 100 lW I 0,1 11 ION Ujii liii 71 III 14 Mg ROW L fl 1 1111111111 co c \ 1 wzr LL.