HEAT EXCHANGER ASSEMBLY

Description

[0001] The invention relates to a heat exchanger arrangement.

[0002] The use of fossil fuels is not only becoming increasingly uneconomical, but is also being increasingly questioned due to its associated negative impacts on the climate. In addition to increasing the use of renewable energy sources, efficient energy storage systems are also needed. These, combined with intelligent controls for heating or cooling buildings or systems, can reduce energy consumption. Such measures can create significant savings potential regardless of the energy source used, which also offsets the associated installation costs.

[0003] DE 29 26 610 A1 discloses a storage system for providing input heat energy at a low temperature level for heat pump systems, which absorb this energy and release it again at a higher temperature level. A water basin is designed so that its water contents can freeze without damaging the basin, and a heat exchanger system located on or embedded in the basin floor allows the cooling and freezing heat of this basin to be fed to the cold side of a heat pump.

[0004] In addition to the use of an artificial water basin, it is also known to use natural water bodies as a storage medium.

[0005] For example, DE 10 2015 104 909 A1 discloses an energy storage device which has a heat exchanger which is arranged floating on a lower basin which is preferably designed as a lake and can be filled with water via a first supply line, wherein water from the lower basin and coolant penetrating the heat exchanger can be supplied to a heat pump in separate circuits via a second supply line, so that energy can be extracted from the water of the lower basin via the heat exchanger by freezing the water of the lower basin or in the form of sensible heat and can be passed on to a consumer for heat dissipation and / or cold dissipation.

[0006] Furthermore, DE 10 2015 121 177 A1 discloses a floating device for introducing thermal energy into a body of water and for extracting thermal energy from the body of water. The device comprises a water heat exchanger which, after the device has been inserted into the body of water, is immersed in the water and has an inlet and an outlet for a heat transfer fluid that can transfer thermal energy to the body of water or extract thermal energy from the body of water. The device further comprises an air heat exchanger through which ambient air can pass and which further comprises an inlet for water originating from the body of water with a corresponding outlet, so that water from the body of water can flow through the air heat exchanger, whereby thermal energy can be transferred between the ambient air flowing through the air heat exchanger and the water flowing through the air heat exchanger.

[0007] The devices described above typically work in conjunction with a heat pump installed in a building. This can be supplied with electrical energy, for example, via the power grid or its own power storage unit.

[0008] From WO 2005 / 096715 A2 a heat exchanger arrangement is known in which a radial fan is arranged for forward operation above a heat exchanger, so that the supply air is transported through the heat exchanger to the suction side located in the radial fan and is then transported via the pressure side to an exhaust air opening.

[0009] DE 10 2007 003 568 B4 describes a fan arrangement with a radial fan, wherein the radial fan sucks in air along its central axis in forward operation and discharges it via an external guide vane arrangement.

[0010] DE 10 2017 102 303 A1 discloses a heat recovery device comprising a heat exchanger arranged in a housing sunk into the ground. The heat exchanger has an air inlet and an air outlet, between which an air flow generated by a fan flows. The heat exchanger is arranged in the underground housing to prevent disturbing noise emissions. The underground housing is located within an excavation filled with a drainage material such as gravel.

[0011] JP S55 155125 A shows a thin air conditioner in which a blowing centripetal fan is provided opposite an air outlet and a heat exchanger is arranged around it.

[0012] JP H09 303853 A shows the arrangement of a rectification heat exchanger on an air flow passage located between a cross-flow fan and an indoor heat exchanger.

[0013] In particular, the last mentioned document points out the requirements regarding the resulting fan noise.

[0014] Since, despite the measures mentioned above, the noise level of heat exchanger arrangements, especially due to the acoustic emissions of the fans, is above the perception threshold of most people, the task now arises to specify a heat exchanger arrangement whose acoustic emissions are reduced even further.

[0015] This object is achieved by the features of patent claim 1. Further advantageous embodiments of the invention are the subject of the subclaims.

[0016] Description, especially in connection with the drawing, further characterizes and specifies the invention.

[0017] According to the invention, a heat exchanger arrangement is specified comprising a housing in which at least one supply air opening is arranged on the circumference, a cover which covers the housing on an upper side and in which at least one exhaust air opening is arranged, wherein a backward-operating radial fan is arranged within the housing such that it can generate an air flow directed radially inwards with respect to its axis of rotation between the supply air opening and the exhaust air opening, which air flow flows through at least one air heat exchanger arranged in the housing. The supply air opening is arranged between the cover and the housing, and the air flow generated by the radial fan flows out upwards through the exhaust air opening. It has surprisingly been found that a backward-operating radial fan is suitable for providing the desired ventilation performance with minimal acoustic emissions.Typically, radial fans with a radially outward-directed airflow are used in forward operation, with the air being sucked in towards the axis of rotation. An axial fan is typically used for radial outflow. The advantage of a reverse-running radial fan over an axial fan is that it can be operated at low speed, meaning that almost no perceptible acoustic emissions are generated by the fan running. Reverse operation means that the suction side of the radial fan is located outside the blades with respect to its axis of rotation, whereas the pressure side is located inside the radial fan with respect to the axis of rotation. The radial fan in reverse operation therefore generates an airflow from the outer suction side to the inner pressure side.

[0018] The air heat exchanger is arranged within a housing, whereby the housing has an air supply opening located on the outside with respect to a central axis and an air exhaust opening located on the inside, between which a horizontal air flow is generated by the radial fan, which flows through the air heat exchanger or past the fins of the air heat exchanger in the usual way. The terms inside and outside refer to directions emanating from the axis of rotation of the radial fan, with a component that is closer to the axis of rotation being referred to as inside. The central axis does not necessarily have to be the geometric center of the housing, but rather the central axis is to be understood as a reference point within the housing, around which the radial fan is arranged first, then further out the air heat exchanger and then further out the air supply opening.Usually, but not necessarily, the axis of rotation and the central axis are aligned. The exhaust air opening is arranged above the pressure side of the radial fan so that the air flow generated horizontally on the suction side can leave the housing in a vertical direction on the pressure side. The heat exchanger arrangement is usually positioned so that the axis of rotation of the radial fan is aligned perpendicular to the floor. Compared to the commonly used axial fans, a radial fan in reverse operation has the advantage that it can be designed with a larger diameter, allowing high air volumes to be moved at low speeds and low air flow velocities. The radial fan is advantageously enclosed in the housing in the direction of its axis of rotation, both up and down. The enclosure can also be part of the housing or other components of the heat exchanger arrangement.The maximum transportable air flow can be specified accordingly by selecting the dimensions of the radial fan. During operation of the heat exchanger arrangement, a carrier medium is pumped through the heat exchanger arrangement by an external heat pump, and the radial fan is operated in reverse. Ambient air is thus drawn into the housing through the supply air openings, then guided radially through the air ducts of the air heat exchanger fins to the radial fan, then conveyed by the radial fan to the pressure side, and finally discharged axially from the housing through the exhaust air opening. The air heat exchanger can either be arranged circumferentially around the radial fan or comprise individual blocks arranged around the radial fan. The supply air openings are arranged and dimensioned so that ambient air can flow through the air heat exchanger.

[0019] According to one embodiment, the radial fan has a plurality of blades which are surrounded by a guide arrangement with a plurality of slats.

[0020] Accordingly, a deflector assembly is arranged within the radial fan. It features fins that direct the airflow on the pressure side of the radial fan toward the rotational axis of the radial fan and / or toward the exhaust air openings. Surprisingly, it has been shown that the deflector assembly can further reduce the acoustic emissions of the heat exchanger assembly. Overall, acoustic emissions could be further reduced by the combined use of a reverse-running radial fan and an internal deflector assembly with comparable fan performance.

[0021] According to a further embodiment, the blades of the radial fan and the slats of the guide vane arrangement are curved in opposite directions.

[0022] By varying the curvature of the fins and blades, the air is deflected along the blades of the radial fan. The airflow from the radial fan is deflected by the deflector assembly and directed toward the exhaust air opening or toward the center of the deflector assembly, which ideally coincides with the rotational axis of the radial fan, creating excess pressure there that escapes through the exhaust air opening. It is particularly advantageous if the blades of the radial fan are curved forward for reverse operation and the fins of the deflector assembly are curved backward.

[0023] According to a further embodiment of the invention, the blades of the radial fan and / or the slats of the guide vane arrangement are formed with a constant curvature along and parallel to their vertical axis.

[0024] Each blade or louvre thus has a circular center point offset parallel to its vertical axis, around which the blade is formed with a constant radius and thus with a constant curvature. Alternatively, the blades or louvres could also have a non-constant curvature, in particular such that the curvature decreases towards the axis of rotation. The radial fan is thus advantageously cylindrical, so that the vertical axes of the blades are arranged parallel to one another and parallel to the axis of rotation, wherein the axis of rotation is simultaneously aligned essentially parallel to the central axis of the housing. The central axis of the housing is perpendicular to the cover of the housing. The guide vane arrangement advantageously also has a cylindrical shape, in which the vertical axes of the louvres are aligned parallel to one another and parallel to the axis of rotation of the radial fan.

[0025] According to a further embodiment of the invention, regions tapering inwards are formed between the slats (LA), so that the air flow experiences an increase in pressure towards the inside.

[0026] This configuration increases the airflow pressure inside, allowing sufficient airflow through the air heat exchanger even at low speeds when the radial fan is operating in reverse. Several blades push the air radially inward. Because the pressure increases in the tapered area, the air escapes axially without being set in rotation.

[0027] According to the invention, the air supply opening is arranged between the cover and the housing.

[0028] Accordingly, the supply air openings are aligned horizontally along the center axis of the housing. This has the advantage of preventing or reducing thermal short circuits between the exhaust air and the supply air. Furthermore, such an arrangement is suitable for use with an energy storage system, as described below.

[0029] According to a further embodiment of the invention, the reverse-operated radial fan and the guide vane arrangement overlap at least in sections along the rotational axis of the radial fan.

[0030] Accordingly, the supply air openings of the air heat exchangers of the radial fans and the discharge guide arrangement are positioned one above the other, at least along a common radial jet around the central axis. Air flowing horizontally from the supply air opening to the discharge side of the radial fan thus bypasses the air heat exchanger, the radial fan, and the discharge guide arrangement.

[0031] According to a further embodiment of the invention, the reverse-operated radial fan is driven by an electric motor.

[0032] By using an electric motor, the required airflow can be easily varied. The electric motor can be housed in an insulating layer to largely absorb motor noise within the housing.

[0033] The use of the heat exchanger assembly together with a water storage tank is advantageous. Such a system for energy storage and heat exchange comprises the aforementioned heat exchanger assembly, a water storage tank for storing heat, a water heat exchanger extending into the water storage tank, and a heat pump that can convey a heat exchange medium between the air heat exchanger of the heat exchanger assembly and / or the water heat exchanger, allowing heat to be exchanged. The water storage tank can be sunk into a hole in the ground, and the heat exchanger assembly is arranged on the water storage tank in the direction of the housing's central axis such that at least the air supply openings protrude above the ground.

[0034] Accordingly, one of the aforementioned heat exchanger arrangements is combined with an energy storage unit. The energy storage unit stores heat within a water reservoir or can transfer heat from a heat pump into the water reservoir. The operation of the water heat exchanger, the heat exchanger arrangement, and the heat pump is regulated by a control device. The water reservoir and the heat exchanger arrangement can comprise a common housing.

[0035] Below, some examples are explained in more detail using the drawings. They show: Figure 1 shows a first embodiment of the heat exchanger arrangement in a sectional side view, Figure 2 shows the heat exchanger arrangement from Figure 1in a plan view cut through the central axis, Figure 3 shows a further embodiment of the heat exchanger arrangement in a plan view cut through the central axis, Figure 4 shows a radial fan with a guide arrangement according to a first embodiment in a partially sectioned perspective view, Figure 5 shows the radial fan with a guide arrangement from Figure 4 in a cross-sectional view, Figure 6 shows a system for energy storage in a sectional side view, Figure 7 shows a radial fan according to a second embodiment in a perspective view, Figure 8 shows the radial fan from Figure 7 in a cross-sectional view, and Figure 9 the radial fan from Figure 7 in another perspective view.

[0036] In the figures, identical or functionally equivalent components are provided with the same reference numerals.

[0037] With reference to Figure 1A first embodiment of a heat exchanger assembly WA according to the invention is described below. The heat exchanger assembly comprises a housing GE with supply air openings ZO and, relative to the supply air openings ZO, internal exhaust air openings AO. The designations "internal" and "external" are used with respect to a central axis MA that sits perpendicularly on a cover DE of the housing and penetrates the housing.

[0038] An air heat exchanger LT is arranged internally, starting from the supply air openings ZO. Further internally, a radial fan RL is arranged, to which an after-flow guide arrangement NL is connected. The radial fan RL is driven in reverse by an electric motor MO, so that an air flow LS flows from the supply air openings ZO through the air heat exchanger LT, the radial fan RL and the after-flow guide arrangement NL to the exhaust air opening AO. Accordingly, the air heat exchanger LT is located on a suction side SS of the radial fan RL, whereas the after-flow guide arrangement NL and the exhaust air opening AO are located on the pressure side DS of the radial fan RL. The electric motor MO is arranged within an insulation layer IS for acoustic and / or thermal insulation.

[0039] The air flow LS passes through the housing GE, starting from the supply air openings ZO, largely horizontally, but exits the housing GE vertically through the exhaust air opening AO. With forward operation of the radial fan RL, as is generally considered standard, the flow direction would be reversed. Thus, in forward operation, air would be conveyed horizontally outward from the rotation axis RA of the radial fan RL to the supply air openings ZO. A heat pump (not shown) pumps a carrier medium to the air heat exchanger LT. Heat is then exchanged between the ambient air and the carrier medium in air ducts LK of the air heat exchanger LT.

[0040] In Figure 2 is a plan view of the heat exchanger arrangement sectioned along the axis AA from Figure 1From outside to inside, the heat exchanger assembly WA comprises a housing GE with side walls SW, an air heat exchanger LT, a radial fan RL, a vane guide arrangement NL, and an exhaust air opening AO. A central axis MA of the housing GE runs through the center of the heat exchanger assembly. The central axis MA does not necessarily run through the geometric center of the housing GE, but usually coincides with the rotational axis of the radial fan RL and forms the reference point for the arrangement of all other components. The vane guide arrangement NL is designed as a stator around which the radial fan RL rotates.

[0041] In Figure 3an alternative embodiment of the heat exchanger arrangement WA is shown, in which the housing GE has a rectangular cross-section. The air heat exchanger LT is in turn arranged between the supply air openings ZO and the exhaust air opening AO. The air heat exchangers LT are located on the suction side SS of the reverse-operating radial fan, whereas the after-flow guide arrangement NL is arranged on the pressure side DS of the radial fan RL. The air heat exchangers LT correspond in their extent to the supply air openings ZO. Seals DI can optionally be arranged along the contact surfaces of the cover DE on the side walls SW of the housing GE, which prevent air from being sucked in through the gaps between the cover DE and the side walls SW. Such an arrangement is particularly advantageous when using a free-standing heat exchanger arrangement WA, which, after assembly, is to be surrounded by the housing GE as an enclosure in order to protect it from damage.

[0042] In Figure 4the radial fan RL and the guide vane arrangement NL are shown in a perspective view, with parts of the illustration being cut away. The radial fan RL has blades SC that are curved forwards and whose blade vertical axis HS runs parallel to the axis of rotation RA of the radial fan RL. The guide vane arrangement NL has louvres LA that are arranged with a backward curve with respect to the direction of rotation in reverse operation RB and whose louvre vertical axis HL also runs parallel to the axis of rotation RA of the radial fan RL. Due to the reverse operation RB, the pressure side DS is on the inside, while the suction side SS is on the outside. During reverse operation RB, air is drawn in by the blades SC on the suction side SS and pushed towards the pressure side DS. The guide vane arrangement picks up the air flow generated by the radial fan RL on the pressure side DS and directs it in the direction of the axis of rotation RA.

[0043] Figure 5shows the arrangement of the radial fan RL together with the guide vane arrangement NL in a sectional view perpendicular to the rotation axis RA, which in the selected illustration would be perpendicular to the blade plane. It can be seen that the fins LA of the guide vane arrangement NL and the blades SC of the radial fan RL are designed in such a way that an expansion channel EK forms between adjacent subdivisions, which ensures a pressure change between the suction side and the pressure side. Due to this configuration, the air flow velocity is converted to a change in the air flow pressure, so that sufficient flow through the air heat exchanger is possible even at low speeds when the radial fan RL is operating in reverse.The reverse operation of the radial fan RL is particularly well-suited for use with the air heat exchangers presented here, as the lateral inflow of air through the supply air openings ZO and the upward discharge of the air flow through the exhaust air openings AO perfectly complement a reverse-operating radial fan. The combination of the air heat exchanger LT with another heat exchanger embedded in a fluid is particularly advantageous. Such a system is presented in more detail below.

[0044] In Figure 6an energy storage system is shown which comprises a heat exchanger arrangement WA and a water storage tank WS for storing heat. A water heat exchanger WT is arranged in the water storage tank WS. A transport medium which serves for heat exchange can be pumped through the water heat exchanger WT or the air heat exchanger LT of the heat exchanger arrangement WA by means of a heat pump (not shown). The transport medium is pumped from the heat pump into the lines LG which lead to the air heat exchanger LT and the water heat exchanger WT. The heat exchanger arrangement WA is arranged above the water storage tank WS with respect to the central axis MA of the housing GE. The water storage tank WS is arranged within a hole in the ground ER, with the supply air openings ZO of the heat exchanger arrangement WA protruding above the ground.

[0045] In Figure 7A perspective view of another embodiment of a radial fan RL is shown. The radial fan RL has a grille GT on its top side, which is similar to the one shown in Figure 1 The radial fan RL in turn has several blades SC, which can be set in a rotating motion in reverse operation RB as shown. Inside there are several fins LA. Due to the rotating movement of the blades SC, air is again brought radially from the outside into the interior of the arrangement, so that the air can escape via the grille GT in the axial direction. In contrast to the embodiment according to Figure 4 However, a much smaller number of blades SC and slats LA is provided here.

[0046] The functionality of the radial fan RL can be explained by the Figure 8 better clarify. In Figure 8is a cross-sectional view through the section plane A - A' of the radial fan RL as shown. It can be seen that in reverse operation, several blades SC push air radially inwards. A tapered area forms between the fins LA, as indicated by the distances VB1 and VB2 between two adjacent fins LA. Since a pressure increase occurs in the tapered area, the air escapes axially upwards through the grille GT without being set in rotation. In this way, a low-noise fan operation can be achieved, in which, as for an air heat exchanger LT according to Figure 1 It is advantageous to achieve an air flow radially inwards and axially upwards between the suction side and the pressure side.

[0047] In Figure 9the radial fan RL is shown again in another perspective view. It can be seen that the inner separation edge AK of the blade SC of the radial fan RL has a structure, for example, serrated. This leads to further noise reduction. Furthermore, the separation edge AK is bent towards the grille GT so that the area from which the air exits is not additionally covered by the blade SC. In this way, the size of the outlet opening via the grille GT is optimized. With the measures shown, both a suitably large air flow rate can be directed through the air heat exchanger LT and very quiet or almost silent operation can be achieved. The last aspect in particular is desirable when using a heat exchanger arrangement WA, for example in private households or offices.The invention is not limited to the described embodiments, but the scope of the invention is defined exclusively by the following claims.

Claims

1. A heat exchanger arrangement (WA) comprising a housing (GE) in which an air inlet opening (ZO) is arranged on the circumference, a cover (DE) that covers the housing (GE) on an upper side and in which an air outlet opening (AO) is arranged, a reverse-operated radial fan (RL) being arranged inside the housing (GE) in such a way that it can generate an air flow between the air inlet opening (ZO) and the air outlet opening (AO), which air flow is directed radially inward with respect to the axis of rotation (RA) of said radial fan and which flows through at least one air heat exchanger (LT) arranged in the housing (GE), characterized in that the air inlet opening (ZO) is arranged between the cover (DE) and the housing (GE), and that during operation, the air flow generated by the radial fan (RL) flows upwards through the air outlet opening (AO).

2. The heat exchanger arrangement according to claim 1, wherein the radial fan (RL) has a plurality of blades (SC) that are surrounded by a guide arrangement (NL) having a plurality of fins (LA).

3. The heat exchanger arrangement according to claim 1 or 2, wherein the blades (SC) of the radial fan (RL) and the fins (LA) of the guide arrangement (NL) are curved in opposite directions.

4. The heat exchanger arrangement according to any of claims 2 or 3, wherein the blades (SC) of the radial fan (RL) are formed with a constant curvature along and parallel to their vertical axis (HS).

5. The heat exchanger arrangement according to any of claims 2 to 4, wherein the fins (LA) of the guide arrangement (NL) are formed with a constant curvature along and parallel to their vertical axis (HL).

6. The heat exchanger arrangement according to any of claims 2 to 5, wherein inwardly tapering regions are formed between the fins (LA) so that the air flow experiences an inward pressure increase.

7. The heat exchanger arrangement according to any of claims 1 to 6, wherein the reverse-operated radial fan (RL) and the guide arrangement (NL) are covered at least in portions along the axis of rotation (RA) of the radial fan (RL).

8. The heat exchanger arrangement according to any of claims 1 to 7, wherein the air inlet opening (ZO) is arranged in a sidewall (SW) of the housing (GE) that surrounds a free-standing air heat exchanger (LT).

9. The heat exchanger arrangement according to any of claims 1 to 8, wherein the reverse-operated radial fan (RL) is driven by means of an electric motor (EM).