DE29802426U1 - Room ventilation with heat recovery - Google Patents

Description

DHB-97/01-DEG 12.02.1997

Room ventilation with heat recovery

The invention relates to a room fan with a substantially channel-shaped heat exchanger for ventilating and/or de-ventilating a closed room with optional heat recovery.

A decentralized ventilation and exhaust system, i.e. one located in each individual room, removes used air from the room and brings in fresh air, even when the windows are closed or missing. The outside air supplied can be heated in winter and cooled in summer by the exhaust air flowing in countercurrent. Energy is only needed to drive the two counter-current air flows. Energy consumption is correspondingly low. Heating costs can be saved in winter, and air conditioning can be at least partially unnecessary in summer.

With temperature sensors and, if necessary, other sensors, the use of a room fan with heat recovery can be controlled automatically. A comfortable and healthy room climate can be created with sufficient, needs-based air exchange. Humidity in the indoor air that exceeds the target value is removed, which not only ensures a comfortable stay, but also prevents moisture damage and fungal infestation.

Thanks to the continuous ventilation and extraction, there is never a draft, as is often the case with open windows or large air conditioning systems.
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The possible uses of room fans are extremely diverse; they can be used in homes, offices, commercial premises

but also in assembly rooms and schools, efficiently and practically silently. The devices are equally suitable for standard equipment in new buildings as well as for retrofitting in old buildings.
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In DE, Al 2947232, a heat exchanger with fixed exchange surfaces is described for the transfer of sensible heat. The heat exchangers are arranged in a large recess in an external wall and form an air supply and an exhaust air lock. The counterflow principle is used to recover as much heat as possible. The heat exchanger in the narrower sense consists of a large number of heat-conducting surface elements that are adjacent to one another at a small distance and run in the direction of the air mass flows. These surface elements are arranged like a partition and are airtight. This creates two shaft-like air supply and exhaust air locks, formed at least by the surfaces of a heat exchanger and separated from one another. Although the heat exchangers protrude from the external wall on both sides, their dimensions are essentially limited to the dimensions of the external wall, as is the case with all other known devices of this type.

US-A 4305457 describes several embodiments for the formation of surface elements in heat exchangers, which are suitable for heat exchangers with a round or rectangular cross section. A specific application for room fans is neither mentioned nor suggested.

The present invention is based on the object of creating a room fan which is independent of the dimensions of the "outer wall" and allows a functionally optimal arrangement in the room in any design.

The task is solved by the room fan essentially

a common nozzle for an outside air and an exhaust air duct,

a heat exchanger with heat-conducting surface elements folded or bent at a small distance, which hermetically separate alternating outside air/supply air ducts in the longitudinal direction and exhaust air/exhaust air ducts flowing in the opposite direction,

a non-heat-exchanging exhaust air bypass duct in the area of the heat exchanger with a closing mechanism for the heat exchanger and the exhaust air bypass duct,

at least one supply air outlet opening into the room,

- at least one intake opening for the exhaust air of the room, with an exhaust air filter, and

- at least one supply air and one exhaust air fan each for the counter-rotating, separate air flows

includes.

Instead of the usual large wall openings of, for example, 250 x 250 mm, according to the invention a single small wall opening of, for example, a maximum of 100 mm in diameter is sufficient. The introduction of outside air and the blowing out of exhaust air takes place through the same opening in the outside wall.
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Furthermore, when dimensioning the heat exchanger for carrying out the process, no consideration needs to be given to the thickness of the outer wall; in particular, the length can be several times that of a conventional heat exchanger arranged in the outer wall.

According to a particularly advantageous embodiment of the invention, the supply air flow leaving the heat exchanger can be partially returned to the main flow of outside air in the flow area of the heat exchanger when the outside temperature drops below freezing. The lower the outside temperature, the more heat is already being exchanged.

The supply air that has flowed through the duct is returned through the bypass. This is why it is also referred to as a "frost protection bypass".

The outside air, possibly mixed with supply air, flows in turbulent flow along the heat-conducting surface elements. In technical terms, the outside air entering the heat exchanger is referred to as supply air after it has flowed through it. The exhaust air flowing in the opposite direction is called exhaust air after it leaves the heat exchanger.

The proportion of supply air returned through the bypass is set automatically, for example by pivoting a flap, moving or rotating a slider, or using another mechanical device. These mechanical devices are programmed based on measurements from temperature sensors, but can also be set manually.

In practice, the recycled portion is preferably in the range of 10 to 60 vol.%.

In terms of flow technology, it is essential for optimal heat exchange that the air flows through the heat exchanger in a turbulent rather than laminar manner. This is primarily achieved by arranging surface elements at close distances and, if necessary, further promoted by arranging baffles.

According to a particularly advantageous embodiment of the invention, the supply air flow leaving the heat exchanger can be partially returned to the main flow of outside air in the flow area of the heat exchanger when the outside temperature drops below freezing. The lower the outside temperature, the more supply air that has already flowed through the heat exchanger is returned through the bypass. This is therefore also referred to as an "antifreeze bypass".

The outside air, possibly mixed with supply air, flows in a turbulent flow along the heat-conducting surface elements. In technical terms, the outside air entering the heat exchanger is referred to as supply air after it has flowed through it. The exhaust air flowing in the opposite direction is called exhaust air after it leaves the heat exchanger.

The proportion of supply air returned through the bypass is set automatically, for example by pivoting a flap, moving or rotating a slider, or using another mechanical device. These mechanical devices are programmed based on measurements from temperature sensors, but can also be set manually.

As already mentioned, a significant further development of the invention is that when the outside temperature is below freezing, part of the supply air can be returned to the outside air flow as frost protection.

This is done by a supply air bypass channel that branches off from the supply air channel downstream of the heat exchanger and flows into the main channel for the outside air on the upstream side of the heat exchanger. The supply air that is returned through the bypass can be regulated using adjustable mechanical means. If the temperature sensors detect an outside temperature above freezing, the supply air bypass channel is completely closed. If the outside temperature drops, it is opened more according to the program, which is done using known means.

The surface elements of the heat exchanger must have the highest possible thermal conductivity, but on the other hand they must also have sufficient mechanical stability. Metals that are easy to work with and have a high thermal conductivity coefficient are the best choice, for example aluminum alloys, copper, brass or steel. Even thin plastic films can be used despite their lower thermal conductivity.

be suitable for this purpose.

The surface elements are preferably arranged in such a way that the narrowest possible gaps are created, through which the air flows alternately in one direction or the other. Narrow gaps prevent laminar flow, while turbulent flows generally increase efficiency. A given volume for a heat exchanger must accommodate the largest possible exchange area of the surface elements. This is achieved in particular by bending or folding in a meandering shape. In this regard, reference is also made to the US, A 4305457 mentioned at the beginning.

The installation of adapters for alternating flow through the gaps is assumed to be known to the expert and will not be explained further here.

According to a preferred embodiment, the cross-section of the entire exhaust air duct in the heat exchanger and that of the exhaust air bypass duct are approximately the same size. This ensures that when the flow conditions change and when the entire exhaust air flow is switched from the heat exchanger to the bypass or vice versa, no significant change in the pressure conditions occurs.

The possible uses of a room fan according to the invention are extremely diverse. Construction details can be adapted to the specific use. For example, a room fan arranged approximately vertically along the inside of the outside wall and one arranged approximately horizontally above a window should be mentioned. In both and other variants, the supply air always flows into the room in the area above the floor, while the exhaust air is extracted in the area of the ceiling. The supply air is usually somewhat cooler than the room air, and a "lake of cold air" forms above the floor. This displacement ventilation principle works with absolutely no drafts.

Ventilation and/or de-aeration can be carried out largely automatically thanks to the arrangement of temperature sensors. Programmable microprocessors control corresponding, known actuators. The following are provided for controlling the device:

- Variable speed drive motors for the supply air and exhaust air fans

- an opening and closing mechanism when the exhaust air enters the heat exchanger

a distribution device for opening and closing the supply air bypass duct with step-by-step or continuously adjustable intermediate stages, e.g. a distribution flap - internal and external temperature sensors.

The invention is explained in more detail using embodiments shown in the drawing, which are also the subject of dependent claims. They show schematically: 20

- Fig. 1 an axial section through a vertical

room fan,
-Fig. 2 a radial section according to II-II in Fig. 1,

- Fig. 3 a longitudinal section through a horizontally arranged room fan,

- Fig. 4 a cutaway view of the room fan

according to Fig. 3, from below,

- Fig. 5 a cross section V-V through a heat exchanger

according to Fig. 4,

- Fig. 6 a radial section through a heat exchanger with bent surface elements,

- Fig. 7 a variant of Fig. 6 with bevelled surfaces

chen elements,

- Fig. 8 a closing mechanism for an exhaust air bypass duct,

-Fig. 9 a distribution flap for a supply air bypass duct, downstream of the heat exchanger,

- Fig. 10 a variant of a return of supply air,

- Fig. 11 another variant of a return of

supply air,

-Fig. 12 a longitudinal section through a room fan with a meandering enlarged heat exchanger

length, and

- Fig. 13 the deflection areas according to Fig. 12 in the De

tail .

In Fig. 1 and 2, a closed room 10 is bounded laterally by an outer wall 12 of thickness b, above by a ceiling 14 and below by a floor 16. The other walls of the closed room 10 are not visible in the section.

In the closed room 10, an essentially cylindrical, approximately 1.5 m long room fan 18 is mounted next to the outside wall 12. A small wall opening 20 approximately 50 cm above the floor 16 is penetrated by a laterally angled nozzle 22 of the room fan 18. The nozzle 22 essentially consists of a double-walled pipe, an internal channel 24 for the exhaust air 26 and an annular channel 28 for the outside air 30.

The round duct 24 protrudes significantly, it narrows at the front to form an outlet nozzle 32. In the area of this nozzle, a condensate nose 34 protrudes, from which condensate blown out with the exhaust air 26 drips. The formation of the outlet nozzle 32 and condensate nose 34 also prevents the undesirable admixture of exhaust air 26 with the outside air 30.

A filter box 36 with an outside air filter 38 attached to the nozzle 22 serves as a base for the room fan 18.

The round duct 24 is bent at a right angle in the filter box 36 and merges into an exhaust air bypass duct 40, also designed as a round duct, with the longitudinal axis L. On the filter box 36

A heat exchanger 48 designed as a folded pipe with star-shaped curved surface elements 42 is also arranged in the heat exchanger box 36, which can be seen in particular in Fig. 2. These surface elements 42 with high thermal conductivity separate alternating outside air/supply air ducts 44 and exhaust air/exhaust air ducts 46. The longitudinal surface elements 42 and ducts 44, 46 form the essentially duct-shaped heat exchanger 48. The exhaust air bypass duct 40 has a diameter d of approximately 75 mm, the heat exchanger 48 has a diameter of approximately 125 mm.

A supply air fan 50 diverts the heated outside air, called supply air 52, on the downstream side of the heat exchanger 48 and guides it via a supply air ring duct 54 into the area of the filter box 36, where it exits from supply air outlet openings 56 into the room 10. The ring-shaped supply air duct 54 is formed by removable half-shells 58 and in the present case has an outside diameter f of approximately 150 mm.

The head area of the room fan 18 comprises, in addition to the supply air fan 50 with a drive motor M controlled by a microprocessor 72, an exhaust air fan 60, also with a drive motor M.

An intake opening 62 for the exhaust air 64 of the room 10, which is located above head height, in other words at least 1.70 m above the floor, is closed with an exhaust air filter 66. This is designed depending on the use of the room so that, in particular, slightly harmful emissions can be avoided.

After passing through the exhaust air filter 66, the exhaust air 64 is directed by the exhaust air fan 60 into the exhaust air/exhaust air ducts 46 of the heat exchanger 48. At the downstream end of the heat exchanger 48, the exhaust air 26, as the exhaust air 64 cooled in the heat exchanger 48 is called, can enter the duct 24 and be discharged via the outlet nozzle 26.

If in a heavily contaminated room 10 the exhaust air filter 66 is not sufficient for proper cleaning of the exhaust air 64, the exhaust air 26 must be fed to a special cleaning system.
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For the operation of the room fan 18, temperature sensors 68 are arranged outside and temperature sensors 70 inside, which send corresponding signals to a microprocessor 72, which in turn controls actuating elements (not shown), such as motors for fans and/or adjusting mechanisms for flaps. According to a variant (not shown), the temperature sensors can also be arranged inside the device.

Fig. 3 and 4 show a room fan 18 mounted horizontally above a window, in the area of a curtain board. This is of prismatic shape, i.e. it has an essentially rectangular or square cross-section. The nozzle 22 that passes through the outer wall 12 (Fig. 1) does not consist in the present case of a double pipe, but of a pipe that is halved along the longitudinal axis, with one half forming the exhaust air duct 24 and the other half the outside air duct 28.

The outside air 28 first flows through an outside air filter 28 designed as a coarse filter and then through a second fine filter 74, which can be designed as a suspended matter filter, for example, and retains fine dust particles and/or pollen. An activated carbon filter can also be integrated into the fine filter 74 to bind odors.

The functional part of the heat exchanger 48 consists of parallel surface elements 42 at a distance of 1 to 3 mm, which are bent in a meandering shape at the edge area. The spaces between them serve alternately as outside air/supply air ducts 44 and exhaust air/exhaust air ducts 46, through which air only flows in the relevant direction.

can.

After the supply air fan 50, part of the supply air 52 branches off under the influence of mechanical means known per se or new means shown in Fig. 9 and flows backwards via a supply air bypass channel 76 to the inlet area of the heat exchanger 48 on the inflow side with respect to the outside air 30. There, the branched supply air flow 52 combines with the outside air flow 30 and enters the heat exchanger 48. At very cold outside temperatures, any icing of condensate forming in the exhaust air part of the heat exchanger can be prevented, which is why the supply air bypass channel 76 is also called an "antifreeze bypass channel".

A supply air duct 54 is advantageously inserted into the supply air outlet opening 56, which leads to the floor area and only then allows the supply air to exit into the room. As explained above, this brings significant advantages in terms of ventilation.

The intake opening 62 for the exhaust air 64 is grid-shaped and protects the exhaust air filter 66.

The heat exchanger 48 is closed at both ends. Inlet and outlet openings are formed in a known manner in both end areas 78, 80.

In Fig. 5, the principle of a prismatic heat exchanger 48 according to Fig. 4 is shown more clearly; the air flows do not run along the plane of the drawing as in Fig. 4, but rather transversely to it. In the rectangular channel shown in a shortened cross-section, a surface element 42 of the heat exchanger 48 is bent in a meandering shape and connected to insert plates 82, 84. These are in the front areas 78, 80 (Fig.

4) of the heat exchanger 48 to form inlet and outlet openings. The parallel areas of the surface element 42 have a distance c of approximately 10 mm.

IO

The surface element 42 separates the interior of the heat exchanger 48 into alternating outside air/supply air ducts 44 and exhaust air/exhaust air ducts 46.
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According to a first variant, the surface elements 42 are metal strips with a thickness of 0.1 to 0.5 mm, which is not critical due to the high conductivity. If the surface elements 42 are made of plastic according to a second variant, they are preferably at most 0.2 to 0.3 mm thick, because otherwise the heat transfer would not be sufficient due to the low conductivity.

Fig. 6 shows a round variant of a heat exchanger 48. In the area between the exhaust air bypass channel 40 and the outer casing 86 of the heat exchanger 48, a surface element 42 is bent alternately radially inwards and outwards, resulting in a star-shaped cross section. The surface element 42 is neither in contact with nor connected to the coaxial pipes 40, 86. The outside air/supply air channel 44 extends inwards in the form of ribs, the exhaust air/exhaust air channel 46 extends outwards accordingly, with the rib-shaped channel extensions alternating and thus ensuring good heat exchange.

In the variant according to Fig. 7, a surface element 42 is alternately bent twice inwards and twice outwards. Otherwise, the embodiment according to Fig. 7 corresponds to that of Fig. 6.

Fig. 8 shows a detail of Fig. 1 in area A, the inlet area of the exhaust air 64 into the heat exchanger 48 with the exhaust air bypass duct 40. The heat recovery can be manually switched on and off.

When heat recovery is switched on, on the right

As shown in the second half of Fig. 8, the exhaust air bypass duct 40 is closed with two semicircular flaps 88. The exhaust air fan 60 (Fig. 1) blows the exhaust air 64 between a circular cover plate 90 and an annular front plate 92 in the direction of the two closed semicircular flaps 88 and is redirected there in the direction of the heat exchanger 48.

When heat recovery is switched off, shown on the left side of Fig. 8, the two semicircular flaps 88 are raised. The inlet opening to the heat exchanger 48 is closed with a sliding sleeve 94, the exhaust air 94 flows through the exhaust air bypass duct 40.

Like the semicircular flaps 88, the sliding sleeve 94 is manually adjustable. Of course, the semicircular flaps 88 and the sliding sleeve 94 can also be pivoted or moved with drive elements with the appropriate effort.

In Fig. 9, a detail is shown in area B of Fig. 3, in which part of the supply air flow 52 is diverted into the supply air bypass duct 76 and returned to the main flow of outside air 30 (Fig. 3). A frost protection flap 96 can be pivoted about an axis 98 using a servomotor (not shown). In the area of the closing edge 97 of the pivoting frost protection flap 96, a flexible flow deflection membrane 100, 102 is attached on both sides. One airtight flow deflection membrane 100 is attached to the supply air bypass duct 76, the other membrane 102 to a flow guide plate 104 in the supply air duct 54.

Shown with a solid line, the frost protection flap 96 completely closes the supply air bypass channel 76. A temperature sensor signals to the microprocessor that the temperature of the outside air 30 (Fig. 3) is above freezing point and there is no danger of icing. A corresponding signal to the actuator causes the closing position shown.

The closed position of the supply air duct 54 is shown in dashed lines. If the temperature of the outside air falls below freezing point, the temperature sensor sends a corresponding signal to the microprocessor controlling the actuator, and the frost protection flap 96 is pivoted by an angle that is greater the lower the outside temperature falls. Of course, in practice the supply air duct 54 is never completely closed, otherwise the room would no longer be ventilated. The frost protection flap 96 acts as a distribution flap on the outlet side of the heat exchanger 48 for the supply air returned to the inlet area of the heat exchanger 48 (Fig. 3).

According to the embodiment of Fig. 10, the essential addition of warmed supply air 52 to the outside air 30 with a temperature below freezing point within the scope of the present invention can also be set on the inlet side of the heat exchanger 48. According to Fig. 1, the supply air 52 is guided in an annular supply air duct 54 along the heat exchanger 48 into its inlet area. Part of the supply air 52 does not exit through supply air openings 56 into the room 10, but through an opening 106 in the filter box 36 into the inflow area 108 of the heat exchanger 48 and mixes there with the inflowing outside air 30. This means that the outside air 30 is preheated before it enters the heat exchanger 48 and any icing is prevented.

The inlet opening 106 for the supply air 52 can be closed with an axially movable double sleeve 110, whereby in the present case the supply air outlet openings 56 are opened more at the same time. The double sleeve 110 can be moved continuously manually or with a microprocessor-controlled drive. This allows any ratio between the supply air 52 returned through the heat exchanger 48 and the supply air 52 flowing out into the room 10 to be set.

be asked.

Fig. 11 shows a variant of the distribution of the preheated supply air 52. The mixing ratio of the recirculated supply air 52/outside air 30 can be adjusted using a rotary valve 112, which has slots or holes 114 in one leg that correspond to the supply air outlet openings 56, and slots or holes 116 in the other leg that correspond to the inlet openings 106. When the rotary valve 112 is turned, an increase in the opening 106 automatically results in a reduction in the outlet opening 56, and vice versa.

Fig. 12, 13 show a room fan 18 with surface elements 42 of the heat exchanger 48 that have been enlarged several times, in that they run with the air ducts, the outside air/supply air ducts 44 and the exhaust air/exhaust air ducts 46, in a meandering shape, folded several times or bent with a tight radius. All details using the reference numbers of previous figures are clearly visible, particularly in Fig. 13.

An exhaust air bypass flap 114 is installed in the first bend in the direction of the exhaust air 64. The closing position is shown in dashed lines. The exhaust air bypass flap 114 can be pivoted about an axis 116.

The outside air 30 that is sucked in is guided into the outside air/supply air duct 44 with a portion of the supply air 52 indicated by dashed lines. The proportions can be adjusted, analogously to Fig. 9, by pivoting the frost protection flap 96 with the hermetically connected flow deflection membrane 100, which is referred to as supply air mixing. The adjustment can be made manually or program-controlled, preferably continuously. The outlet area of the supply air 52 is covered by deflection profiles 122 that leave outlet slots open and is thus protected.

Claims (8)

Protection claims 1. Room fan (18) with a substantially channel-shaped heat exchanger (48) for ventilating and/or venting a closed room (10) with optional heat recovery, characterized by the fact that the room fan (18) mounted on the inside of an external wall (12) essentially - a common nozzle (22) for an outside air (28) and an exhaust air duct (24), - a heat exchanger (48) with heat-conducting surface elements (42) folded or bent at a small distance (c), which hermetically separate alternating outside air/supply air ducts (44) in the longitudinal direction (L) and exhaust air/exhaust air ducts (46) flowing in the opposite direction, - a non-heat-exchanging exhaust air bypass duct (40) in the area of the heat exchanger (48) with a closing mechanism (88,94) for the heat exchanger (48) and the exhaust air bypass duct (40), - at least one supply air outlet opening (56) into the room (10), - at least one intake opening (62) for the exhaust air (64) of the room (10), with an exhaust air filter (66), and - at least one supply air fan (50) and one exhaust air fan (60) for the opposing, separate air flows (30,64) includes. 2. Room fan (18) according to claim 1, characterized in that a supply air bypass channel (76) branches off on the downstream side of the heat exchanger (48), which can be partially or completely closed by mechanical means (96, 110, 112) and opens into the inlet region (108) of the heat exchanger (48). 3. Room fan (18) according to claim 2, characterized in that the supply air bypass channel (76) can be partially or completely closed with a pivoting frost protection flap (96) in an adjustable position, which flap (96) preferably has flexible flow deflection membranes (100, 102) extending over a channel (54, 76) on both sides of its closing edge (97). 4. Room fan (18) according to one of claims 1 to 3, characterized in that the surface elements (42) run approximately parallel at a small distance (c) of preferably 1 to 30 mm, and the meandering bent or folded deflections are designed to be star-shaped, stack-shaped or parallel to the longitudinal direction, depending on the cross-sectional shape of the heat exchanger (48). 5. Room fan (18) according to one of claims 1 to 4, characterized in that the cross section of the entire exhaust air/exhaust air duct (46) in the heat exchanger (48) and the cross section of the exhaust air bypass duct (40) are approximately the same size. 6. Room fan (18) according to one of claims 1 to 5, characterized in that the outside air filter consists of a coarse filter (38) and a fine filter (74), in particular a suspended matter and/or activated carbon filter. 7. Room fan (18) according to one of claims 1 to 6, characterized in that the exhaust air duct (24) protrudes from the projecting nozzle (22) and is preferably designed as an outlet nozzle (32) with a condensate nose (34). 8. Room fan (18) according to one of claims 1 to 7, characterized in that the heat exchanger (48) is surrounded by spaced-apart, coaxially formed, removable half-shells (58) which form an annular space (54) for the return of the supply air (52).