Axial fan arrangement

Abstract

An axial fan arrangement comprises an axial fan (11) rotatably arranged in a fan housing (10) and defines an axial direction (L). The axial fan arrangement comprises a volute (2) arranged downstream of the axial fan (11), the volute (2) comprising a volute housing (20) with an inlet (21) having an opening in the axial direction (L) for receiving an outflow (OF) of the axial fan (11) entering the volute (2) and at least one outlet (22, 22', 23) having an opening in the axial direction (L) for releasing the outflow (OF) of the axial fan (11). The axial fan arrangement enables to enhance the pressure increase of the axial fan and allows to use a second fan within the same fan arrangement.

Description

TECHNICAL FIELD

[0001] The present invention relates to an axial fan arrangement and a heat exchanger arrangement comprising such an axial fan arrangement.PRIOR ART

[0002] Axial fans have motor-driven rotating shafts with mounted blades that pull fluid in and force it out in an axial direction parallel to the shaft. They are capable of moving large volumes of fluid, especially air, effectively and efficiently. They have a wide range of applications, for example in HVAC systems of buildings (HVAC = Heating, Ventilation and Air Conditioning).

[0003] In centrifugal fans, also called radial fans, the fluid enters as axial flow and leaves the fan in radial directions. A volute can be used to collect the fluid in a circumferential direction and to force it to flow out at an opening orthogonal to the axis of rotation of the centrifugal fan.

[0004] US 2023 / 0296109 A1 discloses a centrifugal fan arrangement with a volute having a bent outlet duct portion, allowing the air to leave the fan at an angle of less than 90°.

[0005] In CN 110608194 A, a volute of a centrifugal fan arrangement enables an outflow parallel to the inflow of centrifugal fan.

[0006] Axial fans have the advantage over centrifugal fans of generating a higher volume flow. However, they have the disadvantage of generating a smaller pressure increase than centrifugal fans. For this reason, stator elements are often placed downstream of axial fans in order to convert dynamic pressure into static pressure.SUMMARY OF THE INVENTION

[0007] It is therefore an object of the invention to provide an axial fan arrangement with an improved pressure increase.

[0008] This object is solved by an axial fan arrangement having the features of claim 1.

[0009] The inventive axial fan arrangement comprises an axial fan rotatably arranged in a fan housing and defining an axial direction and a volute arranged downstream of the axial fan. The volute comprises a volute housing with an inlet having an opening in the axial direction for receiving an outflow of the axial fan entering the volute and at least one outlet having an opening in the axial direction for releasing the outflow of the axial fan.

[0010] The fluid entering the inlet of the volute has a main flow direction parallel to the axial direction, but preferably has a circumferential velocity component as well.

[0011] The fluid is preferably air.

[0012] In the inventive axial fan arrangement., the inflow and the outflow of a fluid takes place in an axial direction, with the fluid experiencing an additional velocity component in a circumferential direction of the flow. The volute collects the fluid in the circumferential direction to increase pressure.

[0013] The volute housing is also called scroll housing. Preferably, the volute has an increasing flow cross-section from the inlet of the volute housing to the outlet of the volute housing. Preferably, the cross-section is increasing constantly. The increasing flow cross-section imposes a near-uniform back pressure on the first axial fan and contributes to the pressure rise.

[0014] The axial fan may comprise a central hub closing the centre of the fan and usually comprising a motor mount for the motor of the fan. However, the axial fan preferably comprises blades being rotatably arranged within a circumferential gap of the fan housing. Preferably, the gap has the shape of a ring. Preferably, the gap defines a central through-opening.

[0015] This gap and the central through-opening allow mounting a second fan, wherein the first fan arranged in the gap and the second fan arranged in the through-opening are coaxially to each other. In some embodiments, the second fan is a centrifugal fan or a diagonal fan.

[0016] Preferably, the second fan is an axial fan as well or it is a diagonal fan. An inventive fan arrangement comprising to two axial fans or a first axial fan and a second diagonal fan may be named "single-disc co-rotating opposed-flow twin fans".

[0017] Preferably, the volute housing comprises a circumferential opening, preferably, a groove, matching the circumferential gap of the fan housing. This enables the fluid leaving the fan to flow directly into the volute.

[0018] In some embodiment, the volute comprises at least one bent channel leading from the inlet of the volute housing to at least one outlet of the volute housing. The at least one channel preferably forms a curved circle or a spiral.

[0019] In preferred embodiments, the volute comprises a first bent channel leading from the inlet of the volute housing to a first of the at least one outlets of the volute housing and wherein the volute comprises at least one second bent channel leading from the inlet of the volute housing to at least one second outlet of the volute housing. The channels preferably are intertwined, i.e. they are arranged like the windings of a multi-twined thread. The channels preferably form curved circles or spirals. The use of more than one channel enables to have more than one outlet ports or openings of the volute. This ensures a more homogeneous outflow behaviour compared with a volute having a single channel. A more homogeneous outflow ensures that downstream flow components of a system, such as a heat exchanger, are better supplied with flow.

[0020] In preferred embodiments, the first and the at least one second outlet of the volute housing are arranged within a semicircle defined by the first and the at least one second channel and / or the volute housing. Preferably, there are two outlet ports forming two outlets of the volute housing, wherein they are arranged radially to a centre of the volute, wherein the two radii form an angle of less than 180°. The arrangement of two or more outlets of the volute housing within a semicircle ensures a more homogeneous pattern for downstream components, such as heat exchangers which are placed in a tube and whose inlet area is therefore only limited to a semicircle.

[0021] The outlet openings are preferably arranged within half of a cylindrical channel to carry one of two fluid streams of a heat exchanger. A cold fluid stream occupies one 180-degree (half) section of an overall cylindrical duct, while a hot fluid stream occupies the other 180-degree section. The single or double openings belong to just one side of the heat exchanger and preferably fit within a semicircle, meaning the angular extent of the openings are within a 180-degree angle.

[0022] Using a circumferential inlet opening and two outlet openings allow to have a through-opening with a cross-section area, which has approximately the same size as the cross-section area of volute housing.

[0023] Other shapes and arrangement of the outlet ports of the volute housing can be uses as well. preferably, they are optimized with regard to the downstream components.

[0024] In some embodiments, only the fluid of one single fan passes the volute. In preferred embodiments however, the volute housing comprises a through-opening allowing a second fluid flowing unhindered through the volute. This second fluid does not enter the interior of the housing and does therefore not mix with the first fluid provided by the first axial fan. Preferably, the second fluid flows from a downstream side of the volute to an upstream of the volute. This enables the use of a second fan, especially a second axial or diagonal fan, in the axial fan arrangement.

[0025] In preferred embodiment, the axial fan arrangement comprises such a second fan which is arranged in the fan housing. Preferably, it is an axial fan. Preferably, the second fan is arranged in a centre of the fan housing. Preferably, the volute has a through-opening which is arranged in the centre of the volute housing, thereby allowing a second fluid to pass the second fan.

[0026] Preferably, the second fan is an axial fan or a diagonal fan. Preferably, the second fan has a rotation axis which is co-centric with a rotation axis of the first axial fan.

[0027] This fan arrangement enables to combine two fans in a system wherein the pressure increase of the axial fan is improved similar to a circumferential fan. This enables to use two axial fans wherein one fan combines the advantages of axial fans and of circumferential fans. In addition, the two fans can be arranged in the same fan housing.

[0028] The fan housing and the volute housing can be formed as one single housing. Preferably, the volute housing is fastening to the fan housing, preferably detachable fastened to the fan housing. This enables cleaning of the volute channels and of the fans.

[0029] It is another object of the invention to provide a heat exchanger arrangement enabling an optimized inflow behaviour.

[0030] This object is solved by heat exchanger arrangement having the features of claim 15.

[0031] The inventive heat exchanger arrangement comprises the inventive axial fan arrangement, especially the fan arrangement comprising two axial fans, and a heat exchanger arranged downstream of the volute. The heat exchanger arrangement is preferably a unit of a building or room ventilation system, such as a HVAC system.

[0032] Since the pressure increase is improved for each component, the inflow behaviour for each component is increased. This leads to reduced pressure losses in the heat exchanger arrangement.

[0033] Further embodiments of the invention are laid down in the dependent claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings, Figure 1shows a first perspective view of a heat exchanger arrangement according to a first embodiment of the invention; Figure 2shows a second perspective view of the heat exchanger arrangement according to figure 1; Figure 3shows an exploded view of the heat exchanger arrangement according to figure 1; Figure 4shows an exploded view of the heat exchanger arrangement according to figure 3; Figure 5shows a front view of a volute of an inventive axial fan arrangement according to the first embodiment of the invention; Figure 6shows a side view of the volute of figure 5; Figure 7shows a back view of the volute of figure 5; Figure 8shows an exploded view of the heat exchanger arrangement of figure 1 showing the fluid flows; Figure 9shows a perspective view of the volute according to figure 7 showing one fluid flow; Figure 10shows a front view of a volute on an inventive axial fan arrangement according to a second embodiment of the invention; Figure 11shows a side view of the volute of figure 10; Figure 12shows a back view of the volute of figure 10; Figure 13shows a first perspective view of the volute according to figure 10 showing a fluid flow leaving the volute and Figure 14shows a second perspective view of the volute according to figure 10 showing a fluid flow entering the volute. DESCRIPTION OF PREFERRED EMBODIMENTS

[0035] Figures 1 to 9 show a first embodiment of the inventive heat exchanger arrangement. The heat exchanger arrangement comprises a heat exchanger 3 and an inventive axial fan arrangement having a fan unit 1 and a volute unit 2. It is a heat exchanger, preferably a rotary heat exchanger having an upper and lower area for an inflow and an outflow, and most preferred a heat exchanger used for example in HVAC systems.

[0036] The heat exchanger 3 has a housing with an outflow inlet port 30, an inflow inlet port 31, an outflow outlet port 32 and an inflow outlet port 33. Within the body of the heat exchanger 3, an outflow of a first fluid and an inflow of a second fluid are led past each other so that a heat exchange between the two flows happen without the two flows mixing with each other. The fluid is preferably air.

[0037] Heat exchangers are well known in the state of the art. The heat exchanger used in the inventive arrangement can be a known heat exchanger. Therefore, the heat exchanger 3 is only shown schematically in the figures. Especially, only the side of the ports are shown without showing ports 30, 31, 32, 33 having a shape suitable to be connected to the volute 2. In real heat exchanger arrangements, the shape of the ports 30, 31, 32, 33 is formed suitable so that they can be connected to inlets and outlets of the volute unit 2 described below. In addition, the size of the heat exchanger compared with the size of the volute unit and the fan unit is usually not as shown.

[0038] The fan unit 1 comprises a fan housing 10, which preferably has a round cross-section. The housing 10 comprises a flange 100 for connection to a volute housing 20 of the volute 2. The housing 10 further comprises a circumferential gap 101 arranged in an outer area. The gap 101 has the shape of a ring and, it is located in an outer region of the housing 10. The gap 101 provides a ring-shaped through-opening in an axial direction of the fan unit 1 and the axial fan arrangement.

[0039] A first axial fan 11 is mounted in this gap 101. The first axial fan 11 comprises an impeller with blades 111, which are rotatable around the axis L. The axis L defines the axial direction.

[0040] The impeller of the first axial fan 11 as well as the fan housing 10 have a central through-hole, arranged coaxially around the axis L. A second fan 12 is mounted within the central through-hole of the first axial fan 11 and the fan housing 10. The second fan 12 comprises a hub 120 and an impeller with blades 121, wherein the impeller with the blades 121 is rotatable around the same axis L as the first axial fan 11. The second fan 12 is preferably an axial fan or a diagonal fan.

[0041] As can be seen in figures 2 and 4, the rear side 122 of the hub 120 is larger than the front side, which can be seen in figure 3. This is for example the case when the second fan 12 is a diagonal fan.

[0042] The volute unit 2 comprises the volute housing 20 which has preferably the same cross section as the fan housing 10. The volute housing 20 has an inlet 21 which matches the outlet of the first axial fan, i.e. with the circumferential gap. The inlet 21 is a circumferential opening, preferably a groove, arranged in an outer region of the volute housing 20 and being open in the axial direction towards the fan housing 10 and therefore to the circumferential gap101.

[0043] On the side of the volute housing 20 opposite to the volute inlet 21 side, the volute housing 20 has two outlets 22, 23, which are arranged within a semicircle part of the housing. They are preferably arranged at an angle to each other of less than 180° but more than 90° with an intersection point of the angle legs on the axis L of the fan arrangement.

[0044] At least one channel inside the volute housing 20 leads from the inlet 21 to the first outlet 22 and the second outlet 23. Preferably, the at least one channel has a flow cross-section which constantly increases in direction to the at first and second outlet 22, 23. As can be seen in figure 5, an outflow OF of the first fan 11 enters the volute housing 20 along the circumference. The outflow OF has an axial velocity component, as can be seen in figure 9, and a circumferential velocity component, as can be seen in figure 5. In figure 9, only the main axial direction of the flow is shown, for clarity reasons of the picture. The fluid flow OF flows in direction of arrows VF, herein called direction of the volute flow VF. Preferably, a bypass opening 25 is present near the first and second outlet 22, 23, allowing a small part of the volute flow VF passing through the channel to bypass the corresponding outlet and to flow on to the downstream outlet. This small part is shown with the doted arrows BF and the flow is called bypass flow BF.

[0045] As can be seen in figure 5, the inlet 21 therefore leads to two half volutes that are preferably aerodynamically connected to each other in a serially connected manner. In this embodiment by the two bypass openings 25. In other embodiments there is no bypass.

[0046] One of the half volutes is preferably smaller than the other to accommodate the discharge or outlet ports 22 and 23 which lead into the heat exchanger port 31.

[0047] A through-opening 24 is present in the center of the volute housing 20. The through-opening 24 has a size which allows a second fluid flow to pass the volute unhindered. This second fluid flow is sucked in by the second fan 12. Preferably, the size of the through-opening is about the same as the size of the cross-section of the volute housing 20.

[0048] Figures 8 and 9 show the fluid flows. The first fluid flow OF, also called outflow, flows through the first fan 11 into the inlet 21 of the volute housing 20. The flow into the groove-shaped circumferential inlet 21 is shown in figure 9. The first fluid flow OF then passes the two channels and leaves the volute housing 20 through the two outlets 22, 23 before it enters on the downstream side of the fan arrangement into a component, here the heat exchanger 3. This first fluid OF enters the heat exchanger 3 through the outflow inlet port 31 and leaves the heat exchanger 3 through the outflow outlet port 33.

[0049] The second fluid flow IF, also called inflow, is sucked by the second fan 12. The second fluid flow IF enters the heat exchanger 3 through its inflow inlet port 32 and leaves the heat exchanger through inflow outlet port 30. In the heat exchanger 3, the first fluid flow OF and the second fluid flow IF exchange heat. The second fluid flow IF then passes the through-opening 24 of the volute 2 wherein it does not enter the interior of the volute housing 20 and therefore does not mix with the first fluid flow OF. It passes the second fan 12 and flows out into the upstream side of the fan arrangement.

[0050] Figure 10 to 14 show a second embodiment of the inventive axial fan arrangement. Same parts have the same reference numbers. This fan arrangement is preferably also combined with a heat exchanger in the same way as shown and described with regard to the first embodiment.

[0051] The axial fan arrangement and the heat exchanger arrangement differs from the first embodiment in that the volute housing 20 comprises only one single outlet 22' and maybe that the shape of the through-opening 24' in the centre of the volute housing 20 has a different shape. Only one single channel is preferably present within the volute housing 20. The channel is preferably curved in a circle or spiral and extends preferably at approximately one circle or more than one circle. Preferably, the channel has a constantly increasing flow cross-section from the inlet 21 to its outlet 22'. The outflow OF of the first axial fan 11 enters the circumferential inlet 21 of the volute 2 in a main axial direction but having preferably a circumferential velocity component as well. The flow flows along the channel having preferably a constantly increasing cross-section until the outlet 22'. The arrows of the flows are not shown in figure 10 but they correspond to the arrows shown in figure 5, with the difference that there is only one outlet and preferably no bypass opening.

[0052] In other embodiments, the volute housing 20 comprises more than two outlets and more than two channels.

[0053] The inventive axial fan arrangement enables to enhance the pressure increase of the axial fan and allows to use a second fan within the same fan arrangement.LIST OF REFERENCE SIGNS

[0054] 1fan unit 10fan housing 100flange 101gap 11first fan 111blade 12second fan 120hub 121blade 122cover 2volute 20volute housing 21inlet 22first outlet 22'outlet 23second outlet 24, 24'through opening 25bypass opening 3Heat exchanger 30outflow inlet port 31inflow outlet port 32outflow outlet port 33inflow inlet port BFbypass flow IFinflow OFoutflow VFdirection of the volute flow Laxis

Claims

1. An axial fan arrangement comprising an axial fan (11) rotatably arranged in a fan housing (10) and defining an axial direction (L), characterized in that the axial fan arrangement comprises a volute (2) arranged downstream of the axial fan (11), the volute (2) comprising a volute housing (20) with an inlet (21) having an opening in the axial direction (L) for receiving an outflow (OF) of the axial fan (11) entering the volute (2) and at least one outlet (22, 22', 23) having an opening in the axial direction (L) for releasing the outflow (OF) of the axial fan (11) .

2. The axial fan arrangement of claim 1 wherein the volute (2) has a constantly increasing flow cross-section from the inlet (21) of the volute housing (20) to an outlet (22, 23) of the volute housing (2).

3. The axial fan arrangement of claim 1 or 2 wherein the axial fan (11) comprises blades (111) being rotatably arranged within a circumferential gap (101) of the fan housing (10).

4. The axial fan arrangement of claim 3 wherein the gap (101) has the shape of a ring.

5. The axial fan arrangement of claims 3 or 4 wherein the volute housing (20) comprises a circumferential opening (21) matching the circumferential gap (101) of the fan housing (10).

6. The axial fan arrangement of any one of claims 1 to 5 wherein the volute (2) comprises at least one bent channel leading from the inlet (21) of the volute housing (20) to at least one of the at least one outlet (22, 22', 23) of the volute housing (20).

7. The axial fan arrangement of any one of claims 1 to 6 wherein the volute (2) comprises a first bent channel leading from the inlet (21) of the volute housing (20) to a first outlet (22) of the at least one outlets of the volute housing (20) and wherein the volute (2) comprises at least one second bent channel leading from the inlet (21) of the volute housing (29) to at least one second outlet (23) of the volute housing (20).

8. The axial fan arrangement of any one of claims 1 to 7 wherein the at least one channel is curved in a circle.

9. The axial fan arrangement of claims 7 and 8 wherein the first and the at least one second outlet (22, 23) of the volute housing (20) are arranged within a semicircle of a circle defined by the first and the at least one second channel and / or the volute housing (20).

10. The axial fan arrangement of any one of claims 1 to 9 wherein the volute housing (20) comprises a through-opening (24, 24') allowing a second fluid (IF) flowing from a downstream side of the volute (2) to an upstream of the volute (2) to pass the volute (2) unhindered.

11. The axial fan arrangement of any one of claims 1 to 10 wherein the axial fan arrangement comprises a second fan (12), preferably arranged in the fan housing (10).

12. The axial fan arrangement of claims 10 and 11 wherein the second fan (12) is arranged in a centre of the fan housing (10) and wherein the through-opening (24, 24') is a central opening of the volute (2).

13. The axial fan arrangement of claims 11 or 12 wherein the second fan (12) has a rotation axis which is co-centric with a rotation axis of the first axial fan (11).

14. The axial fan arrangement of any one of claims 1 to 13 wherein the volute housing (20) is fastened to the fan housing (10), preferably detachable fastened to the fan housing (10).

15. A heat exchanger arrangement comprising an axial fan arrangement according to any one of claims 1 to 14 and a heat exchanger (3) arranged downstream of the volute (2).

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