DE8711340U1 - Air mixing device - Google Patents

Abstract

Air-mixing device for the mixing chamber 1 of a ventilation installation 1, 2, 3, which has one inlet 4, 5 for each of two part air flows A, U and an outlet 63 for a mixed air flow M, with a number of ducts 6 which adjoin the inlets 4, 5 and pass through the part air flow A or U of the other inlet, and the outlet cross-section of which adjoins the outlet for the mixed air flow M. The duct walls 64 have openings 7, through which parts of the part air flows A, U flow into the respectively adjacent ducts 6. <IMAGE>

Description

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The invention relates to an air mixing device of the type specified in the 5 preamble of claim 1.

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-DE-PS 32 17 803 and consists of a built-in part for a mixing chamber of an air-conditioning system, which is provided with an inlet for two partial flows and an outlet for a main flow, and in which one or more hollow bodies are arranged, which are connected to one of the inlets, pass through the partial flow of the other inlet, and whose outlet cross-section is provided exclusively on the side facing the outlet for the main flow. The outlet cross-section lies in a surface that runs at an acute angle to the longitudinal axis of the hollow body*

The known air mixing device has the disadvantage that the two partial flows only mix at the outlet edge of the hollow bodies, so that only rough mixing of the partial flows can occur. Since the hollow bodies of the known mixing chamber are designed as closed pockets with an open side, partial stratification of the air flows occurs, so that the main flow leaving the mixing chamber on the outlet side has different temperatures distributed over the cross section.

Such mixing chambers are usually used in ventilation systems to mix outside air and

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Recirculated air is used, whereby, particularly at low outside air temperatures, the temperature level of the outside air flow differs greatly from that of the recirculated air flow. For example, if the cold outside air enters the mixing chamber from above, while the recirculated air is fed into the mixing chamber from one end, very low temperatures occur in the upper area of the air outlet cross-section of the mixing chamber due to the large temperature differences between the outside air and the recirculated air, while high temperatures are reached in the lower area due to the warm recirculated air being more effective there. This temperature gradient within the mixed air or main flow leaving the mixing chamber endangers downstream components of the air conditioning system, for example a heat exchanger or preheater, which freezes in the area where the cold outside air predominates in the main flow, so that there is a risk of the downstream heat exchanger or preheater being destroyed, or at least a risk of the air conditioning system malfunctioning.

In addition, with the known mixing devices, there is always a risk of condensation in the mixing device tubes when warmer air passes along the uninsulated cold tubes, which can also lead to operational malfunctions or interruptions.

The invention specified in claim 1 is based on the task of eliminating these disadvantages of the known mixing device and of specifying a corresponding mixing device which achieves an optimal

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Mixing of the partial air flows ensures that the mixed air flow leaving the mixing chamber has no or only slight temperature differences across its cross-section with partial air flows at different temperatures.

The invention is based on the knowledge that, as a result of the openings in the channel walls of the air mixing device, which act like nozzles due to the different pressure conditions within the mixing chamber, parts of the air flows are pressed through the openings and enter the adjacent channel, so that the mixing of the partial air flows takes place essentially within the channels and only a slight residual mixing occurs at the outlet edge of the air mixing device. Different pressure conditions within the mixing chamber are generally given by different amounts of air being fed to one or the other inlet of the mixing chamber, whereby the air flow can be regulated by quantity-influencing built-in components such as louvre flaps, or they can be specifically brought about by special measures on the air mixing device.

What is particularly advantageous about the solution according to the invention is that optimal mixing of the partial air flows takes place over the shortest possible path within the mixing device, so that only minimal pressure losses occur and the mixing chamber can be kept small in terms of its dimensions. The optimal mixing of the partial air flows also ensures that any choice of cross-

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sectional shape of the ducts or duct walls, so that the designer can decide on the position of the air inlets and the

air outlet and thus an optimal location

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j In addition, the optimal mixing of the parts

* air flows ensure that within the mixing device

no condensation can occur on the plates, since even with large temperature differences, there is no danger of cooling of the plates due to the optimal penetration of the

Plates do not exist even in partial areas.

According to an advantageous embodiment of the invention, the openings in the channel walls can be circular or slot-shaped, but any other cross-sectional shape of the openings can also be selected, such as oval or square openings, which may further support the mixing of the partial air flows by creating stronger vortices.

20

A further advantageous embodiment of the solution according to the invention is characterized in that the alignment of the slot-shaped openings is mutually offset by 90°. In addition, the diameter of the openings can vary so that adaptation to the pressure conditions inside the mixing device is possible.

In the case of another preferred further training, the

Channels made of narrow, box-shaped shafts with channel walls arranged parallel to each other, whereby in the area of the

Air inlet cross-sections alternately c^fen the channels

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HS37.G3 Sheet 10

or closed, so that the relevant partial air flow is forced to flow into certain ducts. The individual ducts in the area of the air inlet cross-sections can be covered by closed or perforated insert plates, so that the relevant partial air flow flows into the duct covered with a perforated insert plate in smaller quantities than into the neighboring ducts.

In another advantageous development, the channels in the area of the air inlet cross-sections of the air mixing device are alternately closed at one and the other inlet of the mixing chamber or covered with perforated or slotted inlet plates and open. This ensures that even with the same partial air flow throughput, a pressure gradient that promotes mixing is formed between the individual, neighboring channels, since one or the other partial air flow is stronger in one or the neighboring channel and thus flows through the openings as a result of the pressure difference caused by this in the neighboring channel.

It is also advantageous if deflection projections are attached to the openings, which on the one hand lead to the formation of vortices and on the other hand force parts of the partial air flows to be diverted in the adjacent duct. The deflection projections can be arranged either on one side of the duct walls or alternately on one or the other side of the duct wall or can be tilted and directed in the openings.

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In a further advantageous embodiment of the solution according to the invention ^, a perforated or slotted outlet plate is provided in the area of the air outlet cross-section, which leads to a slightly increased pressure drop, but contributes to an increased mixing of the air streams*

Advantageous further developments of the invention are characterized in the subclaims or are presented in more detail below together with the description of the preferred embodiment of the invention with reference to the figures.

Show it:

Figure 1 is a partially sectioned, perspective view of part of a room ventilation system with a mixing chamber;

Figure 2 is a schematic, perspective view of an air mixing device for the mixing chamber according to Figure 1;

Figure 3 shows a variant of an air mixing device for a mixing chamber according to Figure 1;
25

Figure 4 shows a cross section through part of the air mixing device according to Figure 3;

Figure 5 is a plan view and a cross-section through part of a perforated channel wall;

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Figure 6 is a plan view of part of a channel wall with different?: arrangement and design of the openings;

Figure 7 is a plan view of a portion of a channel wall with deflection projections;

Figures 8 to 1Ö show cross-sections through parts of a channel wall with different deflection projections;
10

Figure 11 a cross section through the front part of a duct wall with different leading edges and

Figure 12 different embodiments of the duct walls or air mixing devices.

Figure 1 shows a schematic, perspective view of part of an air-conditioning system with a mixing chamber 1, a heat exchanger or preheater 2 and a fan 3. The mixing chamber 1 has two inlets 4, 5 through which two partial air flows A, U are led from flow channels not shown in detail, wherein the air flow rates can be regulated by quantity-influencing components such as louvre flaps 41, 51.

In the embodiment shown in Figure 1, the partial air flows, which here consist of an outside air flow A and a recirculated air flow U, are fed into the mixing chamber 1 in the direction of the arrow at an angle of 90°. Both air flows usually have a different temperature.

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ture level on i which is indicated in the illustrated embodiment by filled and open circles« The type of supply of the partial air flows is arbitrary and not limited to the embodiment shown in Figure 1. For example, the partial air flow U can also come from the side or from below, or both partial air flows A, U from

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be carried out.

The partial air flows A, U supplied to the mixing chamber 1 are mixed in the mixing chamber 1 and leave the mixing chamber 1 via the air outlet cross-section 63 as a mixed flow M, which is indicated by the crossed lines. In the embodiment shown, the mixed flow M leaves the mixing chamber 1 in the direction of one partial air flow U, but can also leave the mixing chamber 1 in the direction of the other partial air flow A, depending on the arrangement of the other parts of the air-conditioning system.

In the mixing chamber 1, several flow channels 6 are provided, which are formed by channel walls 64. The channel walls 64 consist of plates arranged parallel to one another with openings 7, and can optionally be provided with insert plates in the area of the air inlet cross sections 61, 62, as explained in more detail below.

The different variants of the design of the air mixing device or the channels 6, the channel walls 64, the openings 7 provided in the channel walls 64 and the leading edges of the channel walls 64 are explained in more detail with reference to Figures 2 to 12.

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^! Figure 2 shows a perspective view of an AIR-

:, mixing device with parallel chambers

nal walls 64 to form narrow, box-shaped channels

* 6, whose air outlet cross-section 63 is raised and optionally

* 5 can be fitted with a perforated or slotted outlet plate 67* The partial air flows exit from

above or below the front side into the air mixture&mdash;

■direction, which is shown in Figure 2 by the arrows.

10

In the area of the air inlet cross-sections 61, 62, the channels 6 are alternately covered by inlet plates 65, 66, so that the partial air flows are directed into every second channel according to the arrows shown.

In this way, for example, the partial air flow passing through the air inlet cross-section 62 is allowed to enter the channel 6a unhindered, while the partial air flow passing through the air inlet cross-section 61 enters the channel 6b unhindered. Due to the perforation of the channel walls 64, some of the individual partial air flows flow into the adjacent channel and mix intensively with the other partial air flow.

The mixing effect is enhanced by the fact that the partial air flows usually have a different throughput, i.e. a different amount of air per unit of time, which causes different pressures in the individual channels 6. These different dynamic and static air pressures cause the openings 7 in the channel walls 64 to act as nozzles through which the partial air flows are directed.

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10

The inlet plates 65, 66 can either be designed as closed plates or be perforated or slotted so that a certain proportion of the respective partial air flow can also penetrate into the relevant channel through the perforated or slotted inlet plate 65, 66. However, since this proportion is small compared to that of the other partial air flow, the proportion of the other partial air flow predominates in the relevant channel and, with its either greater or smaller dynamic air pressure, causes an intensive exchange with the other partial air flow.

Figure 3 shows a variant of the embodiment of the air mixing device shown in Figure 2, in which in the area of one air inlet cross-section 61 the individual channels 6 are alternately covered with inlet plates 65, while the channels 6 in the area of the other air inlet cross-section 62 are open. In this way, the partial air flow entering via the air inlet cross-section 61 is directed into the respective open channels, while the partial air flow entering via the air inlet cross-section 62 is directed unhindered into all channels.

In this embodiment, too, the inlet plates 65 can be completely closed or perforated or slotted, so that either the relevant partial air flow is prevented from entering the relevant channel or that it only enters the relevant channel in a reduced quantity.

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A further variant may consist in the inlet plates being closed in the area of one air inlet cross-section, while those in the area of the other air inlet cross-section are perforated or slotted.
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Figure 4 shows a cross section through a channel 6 with two channel walls 64 arranged parallel to each other.

1 Through the openings 7 provided in the channel walls 64, parts of the respective partial air flow can - as indicated by the arrows - penetrate into the relevant channel 6 and mix with the other partial air flow directed, for example, into or out of the plane of the drawing. One partial air flow enters the relevant channel 6 via a perforated or slotted inlet plate 61.

Figure 5 shows a top view or a cross section through a part of a channel wall 64 with several circular openings 71, while Figure 6 shows top views of parts of channel walls 64 with differently directed slots 72, 73. The slots can be arranged either vertically (slots 72) or horizontally (slots 73) or - as shown in Figure 6c - both horizontally and vertically and thus assume a configuration corresponding to Figure 6c.

As can be seen from the illustrations in Figures 7 to 10, the openings 7 can optionally be provided with deflection projections 8, which intensify the mixing of the partial air flows. These deflection projections can be

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and be directed against the flow direction of the relevant partial air flow. The AD deflection projections 8 according to Figure 8 can be arranged exclusively on one side of the duct wall or can be provided alternately on one or the other side of the duct wall according to Figure 9.

Figure 10 shows a variant in which the deflection projections 911 92 are arranged in the openings in a foldable manner and, depending on the strength of the respective partial air flow, open or close the relevant opening 7 or ensure that corresponding air flow components reach the relevant channel.

The design of the leading edges of the channel walls 64 in the area of the air inlet cross sections 61, 62 can be arbitrary - as shown in Figure 11 - and can also consist, for example, of a flat leading edge 10a, a triangular leading edge 10b, a semicircular leading edge 10c or a trapezoidal leading edge 10d.

Figure 12 shows various top views of individual channel walls or longitudinal sections through the air mixing device according to the invention.* Due to the intensity of the air mixing within the air mixing device and the negligible importance of the air outlet edge, the cross-sectional shape of the air mixing device can be chosen almost arbitrarily. For example, the cross-section of the air mixing device can be square or rectangular, with the partial air flows entering the air mixing device offset by 90° to one another and the mixed air flow in

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Direction of one or the other partial air flow leaving the mixing device. (Figure 12a)

In the same way, the partial air flows can enter the mixing chamber and thus the mixing device via opposite inlets and thus be directed against each other, whereby the resulting mixed flow can leave the mixing device and thus the mixing chamber upwards or downwards. (Figure 12b, 12c)

In a further embodiment, the partial air streams enter the mixing device offset by 90° to one another, while the mixed stream leaves the mixing device at an acute or obtuse angle in relation to one or the other partial air stream. (Figure 12d)

Figure 12e shows a hexagonal cross-section of the air mixing device or a longitudinal section of the cooling walls, where the partial air flows enter via two air inlet cross-sections separated by an edge of the hexagon and the mixed air flow exits through an edge which is also separated from the air inlet cross-sections by a closed edge of the air mixing device.

Figure 12f shows a cross-section of the air mixing device in triangular form with corresponding incoming partial air flows, while Figure 12g shows a circular cross-section of the air mixing device with partial air flows or mixed air flow directed according to the drawing.

Finally, Figure 12h shows a capezoidal cross-section of the air flow direction with partial air streams and

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a mixed air flow/ which are directed according to the arrows shown.

With all the cross-sectional shapes of the air mixing device or longitudinal sections through the parallel duct walls described above, optimal mixing of the partial flows to form a homogeneous mixed air flow is guaranteed, whereby turbulence can also be generated by deflection projections, which

lü effectively increase the mixing effect. The number of openings in the channel walls is arbitrary and can be selected depending on the operating conditions.

The invention is not limited in its implementation to the preferred embodiment described above. Rather, a number of variants are conceivable which make use of the solution presented even in fundamentally different embodiments.

Claims (17)

HANSA Ventilatoren und Maschinenbau NEUMANN GmbH & Co KG 2915 Saterland 2 HS37.G3 18 August 1987 Air mixing device Claims 1. Air mixing device for the mixing chamber of an air-conditioning system, which has one inlet for two partial air flows and one outlet for a mixed air flow, with several channels that connect to the inlets and the partial air flow of the other inlet /2 I I I * &bull; «c ·· ·· · &bgr; ■·· · a A· ■ ■ · &bull; ft ■ «··· a · HS37.G3 page 2 and whose outlet cross-section connects to the outlet for the mixed air flow, characterized, that the channel walls (64) have openings (7) through which parts of the partial air flows (A, Q) flow into the adjacent channels (ü). 2. Air mixing device according to claim 1, characterized
characterized in that the openings (7) of the channel walls (64) are circular in shape» 3. Air mixing device according to claim 1, characterized
characterized in that the openings (7) of the channel walls (64) are slot-shaped. 4. Air mixing device according to claim 3, characterized
characterized in that the alignment of the slot-shaped openings (72, 73) is mutually offset by 90°. 5. Air mixing device according to one of the preceding claims, characterized in that the channels (6) consist of narrow, box-shaped shafts with channel walls (64) arranged parallel to one another. ifi i ii fi Ii Il <iu >< «III III· · 4 4 It 4Ii ill« Il i It I I < I II lit «4 « «II III· · · « III «III! Il Il ·* < HS.-J7.G3 Sheet 3 6. Air mixing device according to claim 5, thereby
characterized in that at least one air inlet cross-section (61/62) of the channels (6) connected to an inlet (4 or 5) is alternately open and closed 5 7. Air mixing device according to claim 5 rdaduroh
_{characterized} in that at least one air inlet cross-section (61, 62) of the channels (6) adjoining an inlet (4 or 5) is alternately covered and open with perforated or slotted inlet plates (65/66). 8. Air mixing device according to claim 6 or 1, characterized in that the air inlet cross sections (61, 62) of the channels (6) adjoining the inlets (4, 5) are alternately closed or covered with perforated or slotted inlet plates (65, 66) and are open. 9. Air mixing device according to one of the preceding claims, characterized in that the air outlet cross-section (63) is covered with a perforated and/or slotted outlet plate (67). 10. Air mixing device according to one of the preceding claims , characterized in that /4 ti ti n ti an HG37.-G3 Sheet 4 the openings (7) of the channel walls (64) are provided with deflection projections (8; 91/ 92). 11. Air mixing device according to claim 10/ characterized
characterized in that the deflection IT UIIUC \ UT / 12. Air mixing device according to claim 10, characterized
characterized in that the deflection projections (8) are arranged alternately on one or the other side of the channel walls (64). 13. Air mixing device according to claim lO, characterized
characterized in that the deflection projections (91, 92) are pivotably mounted in the openings (7). 14* Air mixing device according to one of the preceding claims, characterized in that the air flow catalysts (10) of the channel walls (64) are flat, semicircular, triangular or polygonal. 15* Air mixing device according to one of the preceding claims, characterized in that the channels (6) are rectangular in longitudinal section. i| · it tr ti »»«·»* &bull; « · I . (ill ti i ti »II til· It t 4 4 1 »41 Il *«« · . &bull; *>> »III · · · &bull;■I ««III f I I* * i * 11037*03 Sheet 5 16« Air mixing device according to claim 15, _{characterized} in that the channels (6) have an inclined air outlet section (63). 17. Ventilation device according to claim 15, characterized W ^S &eegr; ^ IC II KS %= f V? IK II ^· *&idigr;&psgr;^&Lgr;%&Lgr;&mgr;^&lgr;·^***«««&mgr; ■ ■«»· as tv «.«>·«>■« &ggr;&ngr; -« / *■ "■ have a triangular/hexagonal or trapezoidal cross-section (63),
10 18* Air filter device according to claim 15, characterized - characterized in that the channel walls (64) have a circular cross-section.