EP3045828B1 - Exhaust air heat utilisation device - Google Patents

Description

The invention relates to an exhaust heat utilization device, comprising a housing with at least two connection openings, a heat exchanger and a drip pan, wherein a connection opening in the flow direction upstream of the heat exchanger and a connection opening in the flow direction behind the heat exchanger is arranged and wherein the heat exchanger is arranged in or above the drip pan ,

In building ventilation systems, also due to current legal requirements, the recovery of heat from the exhaust air flow is becoming increasingly important. So there is the requirement to realize a heat recovery from the exhaust air stream. In addition to meeting the legal requirements regarding energy efficiency, hygiene and fire protection, the solution must also be economical in terms of investment and running costs.

An established system is the heating of supplied air by means of an air-air heat exchanger directly from the exhaust air. In the case of central ventilation systems, which permit large and thus efficient central heat exchanger units, a supply air duct system is required in the building. In addition, a second fan and a second air filter to protect the heat exchanger on the supply side are required for the supply air next to the exhaust fan. In such systems, in principle, the leakage rate is considered, ie how much of the exhaust air used, hygienically questionable, is entered again on the supply side in the building. Equally critical here is the fire situation, where there is a risk that combustion gases from the exhaust air will be carried into the building through the supply air ducts in the event of a component failure, thereby contributing to the spread of hazardous combustion gases or even spreading the fire.

In addition to systems with air-to-air heat exchangers, systems with an air-liquid heat exchanger are also used. The heat energy of the warm exhaust air is transferred in an air-liquid heat exchanger to a liquid of a separate medium cycle. The heat thus available in the medium cycle can then be used, for example, by a heat pump. The raised by the heat pump to a higher temperature level heat energy can, for. B. continue to be used for heating domestic water. This has the advantage that heat accumulation and heat demand show a good agreement, because both the exhaust air heat accumulates year-round, and also the hot water is needed year-round. The use of an air-liquid heat exchanger closes an air leakage flow from the exhaust air to the supply air side, hygienic problems on the supply air side and in case of fire, fire gas transmission from the exhaust air into the supply air in principle. The supply of supply air can be realized by eg humidity-controlled outside air outlets, thus a supply air duct system is completely saved in the building.

When removing the heat energy from the exhaust air, the moisture contained in the exhaust condenses on the heat exchanger. For safe operation of the system, it is important to collect and remove this condensation. Likewise, it should be avoided that this condensate uncontrollably leaves the system and possibly leads to the accident of the environment.

From the prior art, various systems with air-liquid heat exchangers are known, which have collecting devices for the condensed water. The collecting devices are equipped with drains for discharging the condensate. DE 20 2011 004 012 U1 describes, for example, a home automation device for heating and ventilating rooms. The condensate accumulating on the heat exchanger is collected by a condensate tray arranged below the heat exchanger. The condensate is removed via drains on the condensate tray. Basically problematic is the clogging of the processes and drain lines due to algae growth in the system or other contaminants in the condensation. Clogged drains or drain lines then lead to an overflow of the collecting devices and thus to the accident. To solve this problem, three strategies have been developed. On the one hand additional collecting containers are proposed, which are arranged below the endangered by the overflow collecting container.

US 8 869 548 B2 describes a ventilation system, which consists of a housing, a heat exchanger and two collecting devices, wherein a first collecting device is dimensioned smaller than a second collecting device and the first collecting device is disposed above the second collecting device. The first collecting device has an overflow, which is designed so that excess condensed water flows into the second collecting device. From this second collecting device, the condensate is then discharged through processes.

In US Pat. No. 6,895,770 B1 a similar system is proposed, wherein the second collecting device is arranged outside the housing and is connected via connecting lines with the first collecting device. The EP 0 816 767 A2 discloses a device having the features of the preamble of claim 1. Another solution is the cyclical cleaning of the congestion-threatening drains and drains. US Pat. No. 6,442,956 B1 and US 8,840,729 B1 describe each the elimination of deposits within the processes or drain lines using compressed air. For this purpose, a compressed air inlet is integrated in the drain lines. The compressed air inlet is triggered either by a float located in the catcher or by flow sensors located in the drain lines. Another approach is to issue an alarm signal with increasing blockage of the drain lines. US 4,937,559 A describes such a system. In the drain line of the collecting device, a float is arranged, which measures the water level within the drain line, which issued from a defined level of water, an alarm signal because there may be a blockage of the drain line.

All these solutions have basically proven themselves for the intended application. Difficulties arise when leakage occurs in the medium circuit within the heat exchanger. There is then the risk that the heat transfer fluid of the media circulation enters the collecting device and the drain lines in the environment or the wastewater. In particular, water glycol mixtures or other refrigerants are harmful to the environment.

The object of the invention is to provide an exhaust air heat recovery device whose collecting device for the condensed water is designed so that in a leakage of the liquid-carrying system in the heat exchanger, the exiting liquid is not released to the environment.

This object is achieved by an exhaust heat utilization device having the features of claim 1. Preferred embodiments are defined in the dependent claims.

According to the invention, a condensate valve is arranged inside the housing and that this condensate valve is connected via a drain line to the collecting trough and that a condensate line is connected to the condensate valve and that the condensate line is guided out of the housing and that the volume of the collecting trough is greater than the total volume of the liquid-carrying system, the supply connection line and the return connection line. In case of leakage of the liquid-carrying system in the heat exchanger, the condensate valve is closed. The liquid emerging from the liquid-carrying system is collected in the collecting trough. The condensate valve prevents the leakage of the leaked liquid through the condensate line. The volume of the drip tray is designed so that the Liquid that is in the liquid-carrying system of the heat exchanger, in the supply line and in the return line can be fully absorbed.

An advantageous embodiment provides that an exhaust air collecting space and / or an exhaust air collecting space is formed between the heat exchanger and the connection opening lying in the flow direction after the heat exchanger and / or between the heat exchanger and the connection opening lying in the flow direction before the heat exchanger.

It is proposed that the housing has an insulation. This ensures that the heat energy carried along with the exhaust air is not lost via the housing wall to the outside.

Furthermore, it is proposed that the housing consists of interconnected side parts, bottom parts and cover parts. A further embodiment provides that the side parts and / or the bottom parts and / or the cover parts are designed with hinges or joints and / or have doors. This ensures that the housing is easy to open for maintenance, for example, and that parts lying inside the housing can be reached.

The housing is thus completely closed around the drip pan with preferably light-tight material. Since all air and media lines including the condensate line are made of light-tight material according to the prior art, conditions are created that minimize algal growth in the device and in the condensate drain or even completely prevent.

An embodiment provides that the media connections are configured radially separable.

It is proposed that in the flow direction in front of the heat exchanger, an air filter is arranged above the sump and in the flow direction in front of the sump. Dirt particles entrained by the exhaust air thus do not enter the heat exchanger, which would lead to a blockage of the heat exchanger and thus to a reduction of the heat transfer within the heat exchanger.

A further embodiment provides that in the flow direction upstream of the heat exchanger, a temperature sensor and / or a smoke detector and / or a pressure sensor and / or in the flow direction to the heat exchanger, a temperature sensor and / or a Smoke detector and / or a pressure sensor are arranged. Thus, for example, a leakage of the liquid-conducting system in the heat exchanger via a pressure drop in the system can be detected via a pressure sensor in the supply connection line. The registration of such a pressure drop can then be used to control the condensate valve.

It is proposed that an electronic control of the sensors and / or the condensate valve is arranged on the housing. Thus, for example, the status of the sensors can be read with the housing closed or the condensate valve can be controlled from the outside.

One embodiment provides that a siphon is arranged in the condensate line. Thus, an air leakage current is prevented between the device interior and the end of the condensate line.

A further embodiment provides that the flow connection line and the condensate line or the return connection line and the condensate line or the supply connection line, the return connection line and the condensate line form a tube bundle and have a common insulation.

It is proposed that in the flow direction in front of the heat exchanger, a further connection opening is arranged and that a bypass flap is attached to this connection opening. This bypass damper can be controlled, for example, via one of the above-mentioned smoke detectors in the housing, so that in case of fire, a free outflow of smoke and combustion gases, bypassing the arranged upstream of the heat exchanger air filter is made possible.

Furthermore, it is proposed that the heat exchanger and / or the air filter and / or the drip tray are made exchangeable. Thus, maintenance is much easier.

One embodiment provides that a fan is attached to the connection opening arranged behind the heat exchanger in the flow direction. This can support, for example, the removal of the exhaust air.

It is proposed that the connection openings are provided with connection pieces or with cover caps. If the housing has more than the at least two connection openings, wherein the further connection openings are not used, they can be provided with closure lids. On used connection openings, connecting pieces can simplify the connection of connection lines.

An embodiment provides that in the housing, a heat pump is integrated with a circulation pump and that the heat pump is connected to the supply line and the return line of the heat exchanger and thus between heat exchanger and heat pump, a heat carrier circuit is formed and that the heat pump is disposed above the sump and that the heat pump is connected via pipes with another heat circuit and that the volume of the drip tray is greater than the total volume of the heat cycle between the heat exchanger and heat pump. Even for such arrangements, the complete collection of leaking from the heat cycle between the heat exchanger and heat pump liquid is made possible.

It is proposed that the pipelines of the further heat circuit and the condensate line form a tube bundle and have a common insulation.

Fig. 1

erfindungsgemäßes Abluftwärmenutzungsgerät in perspektivischer Ansicht mit geöffnetem Deckelteil

Fig. 2

erfindungsgemäßes Abluftwärmenutzungsgerät mit Ventilator in einer Seitenansicht

Fig. 3

erfindungsgemäßes Abluftwärmenutzungsgerät gemäß Fig. 1 in der Draufsicht

Fig. 4

erfindungsgemäßes Abluftwärmenutzungsgerät in alternativer Ausführung in der Aufsicht

Fig. 5

Detaildarstellung der Anschlussleitungen eines erfindungsgemäßen Abluftwärmenutzungsgerätes

Fig. 6

montierter Zustand eines erfindungsgemäßen Abluftwärmenutzungsgerätes in einer Seitenansicht

Fig. 7

alternativer montierter Zustand eines erfindungsgemäßen Abluftwärmenutzungsgerätes in einer Seitenansicht

Hereinafter, an embodiment of the invention will be explained with reference to the drawings. Show it:

Fig. 1

Exhaust air heat recovery device according to the invention in a perspective view with the cover part open

Fig. 2

Exhaust air heat recovery device according to the invention with fan in a side view

Fig. 3

According to the invention exhaust air heat recovery device according to Fig. 1 in the plan view

Fig. 4

According to the invention exhaust air heat recovery device in an alternative embodiment in the supervision

Fig. 5

Detailed representation of the connecting lines of an exhaust air heat recovery appliance according to the invention

Fig. 6

assembled state of an exhaust air heat recovery device according to the invention in a side view

Fig. 7

alternative mounted state of an exhaust air heat recovery device according to the invention in a side view

Fig. 1 shows an inventive exhaust heat utilization device in perspective view. The exhaust heat utilization device has a housing 2, which consists of cover parts 14, side parts and bottom parts, wherein in the illustration, the cover part 14 of the housing 2 has been removed so that the interior of the exhaust heat recovery device is visible. The bottom part is not visible. Cover part, bottom part and side parts are preferably made of sheet metal. Within the housing 2, a heat exchanger 1 is arranged such that in the flow direction in front of the heat exchanger 1, an exhaust air collection chamber 6 and in the flow direction behind the heat exchanger 1, a continuous air collecting chamber 27 is formed. The exhaust air collection chamber 6 and the exhaust air collection chamber 27 are not mandatory. The flow direction in the housing 2 extends in the illustration from right to left. The heat exchanger 1 is configured as an air-liquid heat exchanger with a liquid-conducting system. The housing 2 has two connection openings 7 for the supply of exhaust air and a bypass flap 25 in the region of the exhaust air collecting space 6, one of the two connection openings 7 and the bypass flap 25 being optional. Furthermore, the housing 2 in the region of the exhaust air collecting space 27 on a connection opening 29 for the discharge of exhaust air. In principle, all connection openings 7 are designed so that a connecting piece 8 or a closure lid 9 can be attached. In the exhaust plenum 6, an air filter 16 is integrated in the flow direction in front of the heat exchanger 1, wherein this is not mandatory. On the housing 2 four feet 28 are mounted, the feet 28 are designed adjustable in height. The housing 2 itself may have a thermal insulation.

Fig. 2 shows an inventive exhaust heat utilization device according to Fig. 1 in a side view, wherein the inner region of the housing 2 is visible. Deviating from Fig. 1 the lid part 14 is mounted on the housing 2. To the connection opening 29, a fan 26 connects, which discharges the exhaust air. The air-liquid heat exchanger has a flow connection line 4 and a return connection line 5, wherein both connection lines 4, 5 each have a media port 3, so that further flow and return lines can be connected and thus a heat carrier circuit is formed. The heat carrier circuit may preferably contain a water glycol mixture or a refrigerant as the heat transfer medium. The heat exchanger 1 is arranged above a drip pan 10. An arrangement within the drip pan 10 is also conceivable. The drip pan 10 is designed so that its volume is greater than the total volume of the liquid-carrying system of the heat exchanger 1, the supply line 4 and the return line 5. The drain pan 10 is followed by a drain line 11, which leads to a condensate valve 12. To the Condensate valve 12 is followed by a condensate line 21. The condensate line 21 is led out of the housing 2.

The drip pan 10 in the housing 2 has two tasks. In normal operation, the condensate valve 12 is opened so that any accumulating condensate is discharged through the drain line 11 and the condensate line 21 to the environment or into a sewer line. In the event of leakage of the heat exchanger 1 or its media connections 3, it is intended to prevent the heat transfer medium from entering the environment as an environmentally harmful medium. In case of leakage, the heat transfer medium is received by the drip pan 10. However, the medium should not flow away via the condensate line 21. For this purpose, the condensate valve 12 is closed, so that the flow between drain line 11 and condensate line 21 is stopped. By dimensioning the collecting trough 10, the entire in the liquid-carrying system of the heat exchanger 1 and in the flow and return connection lines 4, 5 located heat transfer medium can be added.

The air filter 16 is advantageously arranged so that it does not come into contact with the heat transfer medium or the condensate even when the collecting trough 10 is filled.

Fig. 3 shows an inventive exhaust heat utilization device according to Fig. 1 in plan view, with a possible arrangement of the drain line 11 and condensate line 21 is visible. In the condensate line 21, a siphon 22 is integrated. This is to prevent air leakage through an unfilled or partially filled condensate line 21 due to different air pressure levels between the environment and the interior of the device. The siphon 22 is preferably designed as a ball or flap siphon, the embodiment is not limited thereto.

In the exhaust air collection chamber 6, a smoke detector 17 is optionally integrated. This can be used for example for the control of the bypass flap 25. In case of fire so that the bypass valve 25 is opened and a free outflow of smoke and fire gases bypassing the arranged in the flow direction in front of the heat exchanger 1 air filter 16 allows. The connection of the bypass flap 25 is advantageously carried out via identical connection openings 7, which are also used for the inlet of the exhaust air. Advantageously, the same connection dimensions and connecting elements as for the connecting pieces 8 and the closure lid 9 are used for this purpose. The bypass valve 25 can in principle be arranged at any position which also for the inlet of the Exhaust air is possible. For outdoor installation, the bypass flap 25 is preferably designed as an insulated shutter flap. In addition to the housing insulation, the individual slats of the blind flap are also insulated.

In principle, it is conceivable that in the flow direction in front of the heat exchanger 1 outside the insulated housing 2, one or more fans are arranged. Likewise, in the flow direction in front of the heat exchanger 1, one or more fans can be integrated in the device. Furthermore, one or more fans can be arranged in the device in the flow direction after the heat exchanger 1 and before the connection opening 29 of the exhaust air. According to the invention, a pressure sensor 18 is arranged in the feed line and / or a pressure sensor 18 is arranged in the return line.

Optionally, in the flow direction in front of the heat exchanger 1, a temperature sensor and / or a smoke detector 17 and / or a pressure sensor and / or in the flow direction to the heat exchanger, a temperature sensor and / or a smoke detector and / or a pressure sensor arranged. Likewise, an air filter 16 with Differenzdruckaufnehmer for monitoring the degree of contamination of the air filter 16 or optionally an electronic constant pressure control for the exhaust fan with a Differenzdruckaufnehmer for detecting the air pressure in front of and behind the fan be integrated. The sensors are advantageously arranged so that after opening the housing 2, these are freely accessible.

With a pressure sensor 18 in the supply line 4 or the return line 5, the pressure in the closed heat transfer circuit is detected. If a pressure drop is detected by the pressure sensor 18 in the heat carrier circuit, a switching signal for the condensate valve 12 is thus generated. The preferably electromotive actuated condensate valve 12 then moves to the closed position.

On the housing 2, a terminal box 19 with an electronic detection of the sensor data and / or a control of the condensate valve 12 is attached. The sensors or the condensate valve are connected via connection cable 20 to the terminal box 19, wherein the connection cable 20 flexible and designed in their length so that when converting the terminal box 19 to another side of the housing, the connection cable 20 need not be solved. The possibility of the terminal box 19 umzumontieren without having to solve cable connections, allows the use of a standard device under a variety of local conditions.

The housing 2 is designed with feedthroughs 30 such that the connection of the heat carrier lines 4, 5 and the condensate line 21 at different positions on the housing 2 is possible. Unused passages are provided for example with a connection cover 9. In principle, it is advantageous to carry out uniformly all the connection openings 7, 29 and the passages 30 on the housing 2, so that uniform connection sockets 8 or connection covers 9 can be used.

The connection openings 7, 29 are preferably designed as circular openings with screw connections on a concentric circle, a brush, lip or O-ring seal on the cylinder wall and an axial circular flat seal around the connection opening 7, 29 around. This realizes a double sealing system. Furthermore, a conversion of add-on components and caps 9 at any time only by loosening and tightening screw is possible.

The media connections 3 are configured as radially separable connections, preferably flat sealing connections with union nut, whereby after dissolving the media connections 3 of the heat exchanger 1 perpendicular to the axis of the supply and return connection line 4, 5 and can be removed without the preferably rigid lines 4, 5 must be moved.

Basically, the device is suitable for outdoor use on a building roof or for indoor installation in the building. Furthermore, it is advantageous to integrate elements for sound attenuation in the exhaust air heat recovery device.

Fig. 4 shows an inventive exhaust air heat recovery device in an alternative embodiment with the lid open part in the plan. In contrast to the representation in Fig. 3 no vertical upward blower fan 26 is provided. The exhaust air flow is guided via a connection opening 29 with connecting piece 8 from the exhaust air collecting chamber 27. Furthermore, an embodiment is shown without smoke detector 17, without bypass flap 25 and with three connection openings 7, wherein two of the connection openings 7 are provided with a closure lid 9 and a connection opening 7 with a connecting piece 8.

The possibility to supply the exhaust air via different connection openings 7, allows flexible adaptation of a standard device according to the local conditions.

The cover parts 14, side parts and bottom parts of the housing 2, which are equipped with hinges or hinges for opening the housing or the doors on the lid, side and bottom parts are designed in size so that the heat exchanger 1, the air filter 16 or the drip pan 10 can be removed after the release of the connecting elements and can be used again.

Fig. 5 shows how the condensate line 21, the supply line 4 and the return line 5 are led out as an axially parallel tube bundle 23 from the insulated housing 2. The tube bundle 23 has a common for all pipes strong insulation 24 to the outside, the individual lines against each other, however, are only slightly isolated, so that in a cable routing outdoors and low outdoor temperatures during operation, the condensate line 21 of one or both lines 4, 5 is tempered so far that it remains frost-free and therefore functional.

The housing 2 has one or more upwardly hinged cover parts 14 or laterally pivoting doors, which are each secured on one side with hinges 13 and have a stop and a weight relief. Thus, all functional components after opening the lid part 14 or the doors are directly accessible.

Fig. 6 and Fig. 7 show the installation of an exhaust air heat recovery device according to the invention. The device stands on height-adjustable and angle-adjustable feet 28, allowing it to be set up on both level and pitched roofs, with the exact horizontal orientation and fixation being made right on the floor without having to add or remove components.

LIST OF REFERENCE NUMBERS

1

heat exchangers

2

casing

3

media connection

4

Supply connection line, line

5

Return line, line

6

Exhaust plenum

7

port opening

8th

spigot

9

cap

10

drip tray

11

drain line

12

condensate valve

13

hinge

14

cover part

15

shutter

16

air filter

17

smoke detector

18

pressure sensor

19

terminal box

20

connection cable

21

condensate line

22

siphon

23

tube bundle

24

insulation

25

bypass damper

26

fan

27

Exhaust air collection space

28

foot

29

port opening

30

execution

Claims (17)

1. Exhaust air heat utilisation device, consisting of a housing with at least two connection openings, a heat exchanger and a collecting tray, with one connection opening being arranged in the flow direction before the heat exchanger and one connection opening being arranged in the flow direction after the heat exchanger, and with the heat exchanger being arranged in or above the collecting tray, and with the heat exchanger being an air-liquid heat exchanger and the heat exchanger comprising a liquid conducting system, which has a supply line and a return line, and the supply line and the return line each having a media connection, characterized in that
   a condensate valve (12) is disposed within the housing (2), and that this condensate valve (12) is connected via a drain line (11) with the collecting tray (10), and that a condensate line (21) is connected to the condensate valve (12), and that the condensate line (21) is led out of the housing (2), and that the volume of the collecting tray (10) is larger than the total volume of the liquid conducting system, the supply line (4) and the return line (5), and that a pressure sensor (18) is arranged in the supply line (4) and/or in the return line (5), and that a pressure loss detected by this pressure sensor (18) is a condition for a switchover signal closing the condensate valve (12).
2. Exhaust air heat utilisation device according to claim 1, characterized in that between the heat exchanger (1) and the connection opening (29) located in the flow direction after the heat exchanger (1) there is an exhaust air collecting chamber (27), and/or between the heat exchanger (1) and the connecting opening (7) located in the flow direction before the heat exchanger (1) there is an extract air collecting chamber (6).
3. Exhaust air heat utilisation device according to claim 1, characterized in that the housing (2) has an insulation.
4. Exhaust air heat utilisation device according to claim 1, characterized in that
   the housing (2) consists of interconnected side panels, bottom parts and cover parts (14).
5. Exhaust air heat utilisation device according to claim 1, characterized in that
   the side panels and/or the bottom parts and/or the cover parts (14) are equipped with hinges (13) or joints and/or doors.
6. Exhaust air heat utilisation device according to claim 1, characterized in that the media connections (3) are configured being radially separable.
7. Exhaust air heat utilisation device according to claim 1, characterized in that
   an air filter (16) is arranged in the flow direction before the heat exchanger (1) above the collecting tray (10) and in the flow direction before the collecting tray (10).
8. Exhaust air heat utilisation device according to claim 1, characterized in that
   a temperature sensor and/or a smoke detector (17) and/or a pressure sensor are arranged in the flow direction before the heat exchanger (1), and/or a temperature sensor and/or a smoke detector and/or a pressure sensor are arranged in the flow direction after the heat exchanger.
9. Exhaust air heat utilisation device according to claim 8, characterized in that
   an electronic control of the sensors and/or the condensate valve (12) is mounted at the housing (2).
10. Exhaust air heat utilisation device according to claim 1, characterized in that a siphon (22) is placed in the condensate line (21).
11. Exhaust air heat utilisation device according to claim 1, characterized in that
    the supply line (4) and the condensate line (21) or the return line (5) and the condensate line (21) or the supply line (4), the return line (5) and the condensate line (21) form a tube bundle (23) and a have common insulation (24).
12. Exhaust air heat utilisation device according to claim 1, characterized in that
    a further connection opening (7) is arranged in the flow direction before the heat exchanger (1) and that a bypass damper (25) is mounted at this connection opening (7).
13. Exhaust air heat utilisation device according to claim 1 or 3, characterized in that the heat exchanger (1) and/or the air filter (16) and/or the collecting tray (10) are exchangeable.
14. Exhaust air heat utilisation device according to claim 1, characterized in that
    a fan (26) is mounted at the connection opening (29) arranged in the flow direction after the heat exchanger (1).
15. Exhaust air heat utilisation device according to claim 1, characterized in that the connection openings (7, 29) are provided with connecting pieces or sealing caps.
16. Exhaust air heat utilisation device according to claim 1, characterized in that
    a heat pump with a circulating pump is integrated in the housing (2) and that the heat pump is connected with the supply line (4) and the return line (5) of the heat exchanger (1), and thus a heat transfer circuit is formed between the heat exchanger (1) and heat pump and that the heat pump is arranged above the collecting tray (10) and that the heat pump is connected via pipes with a further heating circuit and that the volume of the collecting tray (10) is larger than the total volume of the heat transfer circuit between the heat exchanger (1) and the heat pump.
17. Exhaust air heat utilisation device according to claim 16, characterized in that
    the pipes of the further heating circuit and the condensate line form a tube bundle (23) and have a common insulation (24).

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