DE1114023B - Combined heat and moisture exchanger - Google Patents

Description

Combined heat and moisture exchanger The invention relates to a combined heat and moisture exchanger with a two passages for separate air streams having housing and therein along a closed Path between the passages moving transmission bodies.

When ventilating rooms in winter, it is from the point of view of the In terms of heat economy, it is essential that in the escaping Most of the heat contained in the room air can be recovered from the incoming air to supply cold outside air so that its temperature increases when it enters the room approaches room temperature. For this purpose, heat exchangers are those mentioned above Art developed through whose one passage the air leaving the room flows out and through its other passage the fresh outside air supplied to the room flows in. The transfer body or bodies moving between the two passages absorb heat from the outgoing room air and give it back to the incoming Slict Outside air. Such heat exchangers are sufficient in terms of heat economy very high standards.

In the case of ventilation of rooms in winter, however, there is also the fact that the atmospheric outside air contains, in absolute terms, a very small amount of moisture because of its low temperature despite a high relative humidity content. So if outside air with about 900/9 relative humidity and a temperature of about -20 ° C is supplied to a room in which there is a temperature of about + 20 ° C, the relative humidity of the air after heating is only 501o, which for a comfortable stay in the room is far too low. A plentiful supply of fresh outside air into a room, as valuable as it may be in itself, must not have the consequence that the room air is overdried, and it is the object of the invention to create an exchanger which is also the higher one with high heat economy Absorbs moisture from the escaping air so that it benefits the incoming outside air. Another purpose of the invention is to make the incoming outside air more humid without adding water.

By increasing the efficiency of the heat exchanger, the cooling of the escaping room air go so far that the limit curve for saturated Water vapor is reached, whereby condensate separates out in the exchanger. If the outside temperature is below freezing point, the condensate can flow into Form of ice clog the exchanger. This formation of ice is also related to that Ratio of the moisture content of the indoor air and that of the outdoor air combined. The lower the temperature of the outside air, the greater the risk of ice formation is, d. This means that the risk of ice formation is greatest when the heating system has one Building is the most stressed and consequently the ventilation of the rooms with the highest possible degree of efficiency is particularly urgent. It is therefore another The object of the invention to provide a combined heat and moisture exchanger create, in which a full exchange of air under favorable conditions also can take place when the outside temperature is very low.

When the air is oppressive and humid in summer, the circumstances are good just the opposite in comparison to the conditions described above. the Outside air can then have the higher moisture content, especially when the indoor air is conditioned to its temperature and its moisture content to belittle. It is an advantage that the outside air does not have a high moisture content to enter the room. In addition, when the outside temperature is high, it is it is essential to be able to carry out an air exchange without at the same time a large amount of heat is introduced into the room. It is therefore even The object of the invention to create an exchanger that also has this for hot and humid Summer weather meets applicable conditions. In particular, the invention aims in this context to create an exchanger with simple switching can operate in both winter and summer.

The task at hand is essentially solved by that two transmission bodies designed as rotors are axially one behind the other are arranged and are successively flowed through by each of the two air streams and the one transfer body as a heat transfer body or heat and moisture transfer body and the other as a moisture transfer body or a heat and moisture transfer body is formed and in the one passage between the two transmission bodies one the moisture content of the air flow flowing through it at the transition from one Transfer body is arranged on the other lowering device.

The device reducing the moisture content can according to a proposal of the invention be designed as a radiator which can be regulated by means of a hygrostat is, in turn, of the relative humidity of the air after this has crossed out both transmission bodies, is actuated.

According to another proposal of the invention, the moisture content lowering device be designed as a rotational transmission body, which along a closed path between the one passage and another passage moves, the air from a place, z. B. a room with a different temperature or a different moisture content than that of the air flow in the first-mentioned passage, is fed.

One or both of the transmission bodies designed as rotors are made of threads, tapes or foils with per se or through additives created hygroscopic properties with low average Are stacked at intervals.

The drive of the transmission body can be the same or different Speed. The speed is useful for the one that transfers the moisture Body larger than for the body transferring the heat.

There are exchangers with rotating transmission bodies in two adjacent ones Lines known, one of which transfers moisture and the other heat can. The body that transfers the moisture is a so-called humidification wheel educated. However, this moistening wheel does not correspond to the moisture transfer body according to the invention, because it must always be immersed in water and is only from an air flow, namely the air flow coming from the outside air.

There are also known drying devices, one of several Disks or drums have composite rotor, the disks or Drums contain a moisture absorbent material through which the Air used for drying should as far as possible be withdrawn from humidity. This moisture extracted from the air has no further function, while with The subject of the invention is the humidity of an escaping to the atmosphere Air flow can be transferred to an air flow sucked in from the atmosphere target.

Circumferential transfer body for heat and transfer body for Moisture are known per se. According to the invention, such transmission bodies are now arranged together in an exchanger, so that both heat and humidity can be transferred from one air stream to another, the air streams flow through the transmission bodies one after the other.

Details of the invention will emerge from the description of some Exemplary embodiments shown in the drawing. It shows Fig. 1 according to of the invention designed heat and moisture exchanger in axial section according to line 1-I of Fig. 2, Fig. 2 shows a cross section according to line 11-1I through the heat and moisture exchanger according to FIG. 1, FIG. 3 shows an axial section through a modified embodiment of the invention, the one shown on the left in the figure Part coincides with the right part of FIG. 1, and FIG. 4 shows the installation schematically of the heat and moisture exchanger in an existing air conditioning system.

The housing 10 of the heat and moisture exchanger, hereinafter referred to as exchanger for short, is divided into two chamber-like passages 14 and 16 with the help of an axially extending partition wall, of which the passage 14 by means of an outlet pipe 18 with the outside air and by means of an inlet pipe 20 and one Fan 22 is in communication with a space to be ventilated, while the passage 1.6 by means of an inlet pipe 24 and a fan 26 with the outside air and. communicates with the space to be ventilated by means of an outlet pipe 28. In the pipes 20 and 24 control organs, for. B. throttle valves 29, 30, arranged. Air filters 32 and 34 are arranged immediately on the pipelines 20 and 24 and adjoin the passages 14 and 16, through which the outside air before it enters the passage 16 and the room air before it enters the passage 14, are cleaned. The two air filters can be of a known type and expediently consist of easily exchangeable units.

In the exchanger according to FIGS. 1 and 2 there are two transmission bodies 36 and 38 rotatably mounted in the form of rotors. They preferably consist of around a hub 39 spirally wound strips 40 and 42, which in a known manner from a flat and a corrugated or provided with protrusions of another shape Layer can be composed, whereby between the bands close to the rotor axis parallel channels are formed. In the drawing is for clarity the corrugated layer not shown.

Such a layer made up of layers stacked like lamellas composite transfer body has high transition numbers for both heat as well as moisture when the individual layers are at a medium distance are arranged from each other, which is smaller than 1.5 mm, suitably smaller than 1 mm, e.g. B. 0.2 to 0.6 mm. This means that the distance between the flat layers is at most 3 mm, preferably less than 2 mm. Furthermore can the layers be hygroscopic, as in certain cases, used as tape material Paper types is the case, especially if wool fibers or fibers of other very much hygroscopic materials are mixed into the paper. A wool fiber takes z. B. twice as much moisture as a wood or cellulose fiber. In manuals The hygroscopicity is indicated by the amount of water that the substance contains a given relative moisture content is able to absorb, for example Grams of water per 100 g of the fabric in the dry state.

The layers can also consist of a sheet or film-shaped carrier with an addition or a coating of a hygroscopic substance, such as fine powder Silica gel. It is advantageous here if this substance is insoluble in water is. This is because water-soluble, moisture-absorbing substances follow as a result of capillary action in the carrier the water absorbed by the substance on its way from a point with higher to a place with lower humidity. After a certain time has thus taken place a rearrangement of the hygroscopic substance, so that the Exchanger with a larger or smaller part of its volume is hygroscopic becomes inactive.

The spirally wound tape roll of each rotor 36 and 38 is inserted into a solid hollow cylinder 44, one edge 46 of which is bent inwardly onto the tape roll, while the other edge 48 is angled outwardly to form a flange. Each rotor 36, 38 formed in this way lies in a circular opening in a respective transverse wall 50 firmly connected to the housing 10, seals against this opening and extends across the two passages 14 and 16. The rotors are sealed against the intermediate wall 12, for example by working on the labyrinth principle seals 52, so that a direct overflow of air is prevented from one passage into the other. The rotors can be driven by a common motor; however, each rotor is expediently provided with its own drive motor 54 or 56. An annular flange 58 is arranged on the outer jacket of each cylinder 44 and is mounted in several, for example three, support rollers 60 which are rotatably mounted on the housing and are expediently designed as double cones. Against the annular flange 58 is a drive pulley 62, for. B. a friction wheel, which sits on a shaft 64 and is driven by the drive motor 54 and 56 via a gear transmission 66. In the passage 14, a heating device, for. B. an electric heater 68, arranged for heating the air. The thermal effect of the heater 68 can be regulated with the aid of a hygrostat 69 located in the outlet pipe 18 of the passage 14.

The body of the rotor 36 is hygroscopically effective, so that when Circulation of the rotor both heat and moisture from the one air stream can convict the other. Although not a condition, it is beneficial that the body of the rotor 38 also has the same hygroscopic properties and at the same time is a good heat exchanger.

The mode of operation of the exchanger in winter, i.e. during a cold season, is as follows: It is assumed that the outside air has a temperature of -20 ° C. At such a low temperature, their relative moisture content is always very high and 90% can be used. The room air has a temperature of -f-20 ° C and a relative humidity of 60%. For reasons to be explained in more detail later, it should also be assumed that the outside air in the passage 16 has been heated to + 20 ° C. by the rotor 38 and that at the same time its relative moisture content has decreased to 20 to 301 / o.

When this preheated outside air in the passage 16 through the rotor 36 passes through it, it is from the escaping room air, which during the circulation of the rotor flows through the passage 14, so influenced that the escaping Room air gives off part of its moisture to the preheated outside air, so that depending on the efficiency of the rotor, this has a relative moisture content of contains about just under 60%. Their temperature is the same as that of the room air, namely + 20 '@' C. The escaping room air still has a temperature behind the rotor 36 of + 20 ° C. In this rotor 36 there is only one transfer of moisture took place by extracting moisture from the escaping room air and removing this Moisture has been transferred into the incoming outside air.

Heat is supplied to the escaping room air through the heating element 68, but only so much that their temperature is increased to, for example, + 25 ° C. A combined heat and moisture exchange then takes place in the rotor 38. The incoming cold outside air is heated to the + 20 ° C assumed above, and the escaping room air emits the appropriate amount of heat, so that their Temperature at the exit from the exchanger z. B. -15 ° C and that they have a has a relative moisture content of about just under 100%. Part of theirs Moisture content has passed into the incoming outside air at the same time. The supply of heat through the radiator is necessary to prevent condensation of moisture in the rotor 38 or in the outlet of the passage 14 to avoid.

In this example it was assumed that the temperature and humidity conditions are such that the rotor 36 serves only as a moisture exchanger. Of the required heat exchange then takes place entirely with the help of the rotor 38. This if the efficiency of the heat exchanger is intentionally worsened, namely, as can be seen from the above, a condensation in the exchanger to prevent. The ability of the exchanger to transfer moisture without condensation, was increased, and thus the permissible relative humidity in the room was increased.

If, however, a deterioration in the efficiency of the heat exchange is to be avoided with the extraordinary conditions assumed above with regard to the temperature of the outside air, the amount of air flowing through the passages 14 and 16 in the unit of time can be reduced with the help of the throttle valves 29 and 30. Likewise, the supply of heat through the heating element 68 can be adjusted in such a way that the rotor 36 transfers mainly moisture and thus no or only a small amount of heat. Simultaneously with the setting of the exchanger to the highest efficiency with regard to heat transfer, which is effected by reducing the amount of air, its efficiency with regard to moisture transfer increases, whereby it is put to an increased degree in a position to transfer moisture without condensation.

Which of the two modes of operation described above, d. H. large amount of air and somewhat reduced heat transfer efficiency or higher efficiency the heat transfer and a slightly reduced amount of air are preferred in individual cases depends on the conditions prevailing in the room.

The heat supply through the heating element 68 can, however, also be adjusted in this way be that the incoming outside air behind the rotor 38 has a temperature, which is lower than that of the room air. This can be done in less cold climates Conditions may be appropriate, e.g. B. at outside temperatures up to about 0 ° C. In this case, the rotor 36 also acts as a heat transfer body. if the temperature of the outside air behind the rotor 38 in the passage 16, e.g. B. + 10 ° C is, so the rotor 36 should ensure that this temperature continues to in the proximity of the temperature of the room air is increased. Will the heat supply of the radiator 68 completely switched off, the proportion of the rotor 36 in the heat transfer reaches its maximum value and is related to the heat transfer through the rotor 38 in one Ratio that depends on the areas, the heat transfer coefficients and the speeds of the both rotors is determined. Optionally, it can be advantageous that of the radiator 68 so much heat is supplied that the temperature of the outside air behind the rotor 38 is higher than that of the room air. Usually, however, the aim is from the To supply the heating element 68 as small an amount of heat as possible, because in most cases another heating device in the room, e.g. B. central heating body, available is. The heater 68 can also be in the passage 16 between the two rotors to be ordered. The mode of operation is basically the same in this case like the one previously described.

The humidistat 69 can be used to supply heat to the radiator 68 regulate automatically so that the relative Moisture in the exchanger or in the outlet pipe 18 is always less than 1000.10 is. The throttle valves 29, 30 can be manually or automatically, depending on the Outside air temperature, adjustable.

In summer, that is, during a warm season, the exchanger works with the heating element 68 switched off, and its task is to prevent heat and moisture from penetrating into the room, which may be air-conditioned, when the outside temperature and outside humidity are higher. Depending on the prevailing conditions, the exchanger works with the two rotors 36 and 38 as heat and / or moisture exchangers with reference to the effect described above, with the only difference that the transfer of heat and / or moisture from the incoming outside air to the escaping room air takes place . The embodiment of the exchanger modified in FIG. 3 differs from the embodiment according to FIG. 1 in that the stationary heating element 68 is replaced by a rotation transmission element 80, i.e. a rotor, which extends from a third chamber-like passage 84 next to the passage 14 extends through the boundary wall 82 of this passage into him. The rotor 80, the outer circumference of which is indicated in FIG. 2 by a dash-dotted line, is a heat exchanger without the ability to transfer moisture. It is designed and supported essentially in the same way as the rotors 36 or 38, but is considerably narrower than these in the axial direction. The material of the transmission body in the rotor 80 should be completely or almost completely unshygroscopic, as is the case, for. B. can be achieved by using metal foils and certain plastic foils. The rotor 80 is sealed at its point of passage through the boundary wall 82 with respect to the passage 14 by seals 86, which prevent leakage between the passages 14 and 84, and is driven by a drive motor 87 in the manner described above. The passage 84 is connected via an air filter 88 and an inlet pipe 90 to the fan 22 which, as already described, conveys the used room air through the inlet pipe 20 into the passage 14. A small amount of this room air now also reaches the passage 84. In the inlet pipe 90 there is again a control element, e.g. B. a throttle valve 92 is arranged, the position of which is controlled by the hygrostat 69 with. The air exiting passage 84 returns through exhaust and connecting conduit 94 back into the room.

In this embodiment, the temperature of the outside air in the passage 16 behind the rotor 38 is always lower than that of the room air, so that the rotor 36 transfers heat from the escaping room air to the incoming outside air. If the temperature of the room air z. B. + 20 ° C, this can drop to about + 12 ° C in the rotor. The rotor 80 then heats the air in the passage 14 to, for example, + 15 ° C. The outside air in turn leaves the rotor 38 at a temperature which is slightly below that of the room air after it has passed through the rotor 36. The heat exchange through the rotor 36 increases the temperature of the outside air to slightly below -I-20 ° C. When entering the rotor 80 , the room air flowing through the passage 84 has a temperature of -! - 20 ° C, and the temperature drop in this Rotor 80 depends on the amount of air flowing through it.

If the escaping room air does not need to be heated, then the drive of the rotor 80 is switched off and at the same time the inlet pipe 90 closed with the help of the throttle valve 92.

In the installation example of a heat and moisture exchanger according to the invention shown schematically in FIG. 4, an air conditioning system 98 of conventional design and mode of operation is provided for a room 96. This known system here comprises a humidifying device and a refrigerating machine or a heating system. The system can be designed so that it can influence the room air both in winter and in summer. It is in communication with the room via a fan 100 and an air inlet duct 102. As usual, an air outlet line 106, through which the room air escapes from the room 96, is connected to an exhaust line 104 which opens into the atmosphere from the air conditioning system 98 . The escaping room air can thereby be divided into two air streams, one of which returns to the air conditioning system 98 and thus to the room 96, while the other is diverted to the open atmosphere , if necessary with the aid of a fan 108. The ratio between the recycled in the conditioned-air amount and the air escaping into the atmosphere air volume is in practice about 4: 1. The recirculated in the conditioning air is mixed with fresh outside air, which is supplied through a pipe 110 of the air conditioner 98th

An exchanger 112 designed according to the invention is connected to the fan 108 and to the conduit 110 . This exchanger now enables the excess of moisture and heat in the escaping room air to be transferred into the inflowing outside air in winter, while the ratio is reversed in the summer as described above. Thanks to the improved heat economy or moisture transfer in the exchanger, the proportion of outside air in the air flowing into the space 96 can be increased significantly. Accordingly, up to half of the room air leaving the room 96 through the air outlet line 106 can escape through the exchanger 112 into the open atmosphere, with a correspondingly smaller amount of air returning to the air conditioning system 98 to be supplemented there with fresh outside air from the pipeline 110 .

The invention is of course not limited to the embodiments shown limited, but can in many ways within the spirit of the invention be modified. If the heat and moisture exchanging substance in the Rotors is filiform, it has hygroscopic properties in the manner described above. In order to achieve high transition numbers, it is essential that the threads are thin. With a circular cross-section, they can have a diameter of the order of magnitude less than 0.2 mm and preferably less than 0.1 mm, e.g. B. 0.02 to 0.05 mm, to have. Furthermore, the flow gaps between the threads should be narrow.

The rotor 36 can be at higher, the same or lower speed rotate as the rotor 38. The transmission body of the rotor 38 is shown in the Embodiments stronger in the axial direction than that of the rotor 36. The rotors However, 36 and 38 can have the same axial strength with otherwise the same structure to have; but the rotor 38 can also be narrower. This means that with a certain speed the transmission capacity of the two rotors must be the same or that of one rotor can exceed that of the other rotor.

The invention also applies to the ventilation of freezer or cold storage rooms applicable. This application corresponds to the application in winter described above, with the only difference that the room has the lower temperature and the lower Has moisture content, so that heat and moisture are prevented from doing so need to get into the room.

In order to avoid moisture condensation in the rotor 38 , part of its moisture content can be withdrawn from the air flow behind the rotor 36. For this purpose, the rotor 80 serving as a heating device can consist of a hygroscopic material in the same way as the rotors 36 and 38. In connection with the description of FIG. 3 it was emphasized that the air temperature in the passage 14 behind the rotor 36 is lower than in the room. Furthermore, the relative moisture content increases, so that it is higher behind the rotor 36 and thus on the inlet side of the third passage 84 than in space. By rotating sufficiently slowly, the rotor 80 can transfer moisture from the air in the passage 14 to the air in the passage 84 without any significant amount of heat being transferred into this latter air. Optionally, the rotor 80 can serve both to supply heat to the passage 14 and to remove moisture from this passage.

Claims (7)

PATENT CLAIMS: 1. Combined heat and moisture exchanger with a housing having two passages for two separate air flows and transfer bodies therein moving along a closed path between the passages, characterized in that two such transfer bodies (36, 38) are arranged axially one behind the other and one after the other are flowed through by each of the two air flows and one transfer body is designed as a heat transfer body or heat and moisture transfer body and the other as a moisture transfer body or heat and moisture transfer body and in one passage (e.g. 14) between the two transfer bodies (36, 38 ) a device (68, 80) which lowers the moisture content of the air flow flowing through at the transition from one transmission body (36) to the other (38) is arranged. 2. Heat and moisture exchanger according to claim 1, characterized in that the two transfer bodies (36,38) transfer both heat and moisture. 3. Heat and moisture exchanger according to claim 1, characterized in that that the device which lowers the moisture content is designed as a heating element (68) is. 4. Heat and moisture exchanger according to claim 3, characterized in that the heating element (68) can be regulated by means of a hygrostat (69) which in turn is actuated by the moisture content of the air after it has passed through both transmission bodies (36, 38) . 5. Heat and moisture exchanger according to claim 1, characterized in that the device reducing the moisture content is designed as a rotary transmission body (80) which moves along a closed path between the one passage (14) and a third passage (84) , the air from one place, e.g. B. a room with a different temperature or different moisture content than that of the air flow in the first-mentioned passage (14) is supplied. 6. Heat and moisture exchanger according to one of the preceding claims, characterized in that the transfer body or bodies (36, 38) are constructed from threads, sheets or foils (40, 42) with hygroscopic properties that are present or created by additives. 7. Heat and moisture exchanger according to claim 6, characterized characterized in that the sheets or foils (40, 42) with small average intervals are stacked on top of each other. B. heat and moisture exchanger according to one of the - the preceding claims, characterized in that the transmission body (36, 38) are driven at speeds appropriate for the moisture transferring Body are larger than for the body transferring the heat. Considered Publications-USA.-Patent Nos. 1241299, 1912 784, 2,464,766, 2,499,411, 2,527,569, 2,662,607.