EP4339529A1 - Service connection for a heat pump housing - Google Patents

Abstract

Method and device for inerting an encapsulated heat pump housing by means of a service connection for an encapsulated heat pump housing, the capsule comprising at least part of the refrigerant circuit and the capsule having a connection for a line which leads from the capsule to the outside, and the service connection the interior of the capsule connects with your outside space and has a non-return valve.

Description

The invention relates to the indoor units of heat pumps, in particular split heat pumps and split air conditioning systems, which use a flammable refrigerant, such as R290, R32, R1270, R600a or R454C. Split systems always consist of an outdoor unit and an indoor unit; the indoor unit is installed in the interior of a residential or commercial building. In such systems, it must be ensured that no flammable refrigerant can escape into the installation room.

In order to achieve this, such split devices can either be designed in such a way that all lines and devices carrying refrigerant are arranged in the outdoor unit and only one heat transfer medium circulates between the outdoor unit and the indoor unit. Such solutions are preferred when multiple indoor units are to be connected to one outdoor unit. Or you can circulate the refrigerant itself between the outdoor unit and the indoor unit, which can be advantageous if the pipe lengths can be kept short and the amount of refrigerant as well as the device output are low. In such cases, all equipment except the indoor unit heat exchanger is placed in the outdoor unit to minimize the risk.

This indoor unit heat exchanger is considered a critical part. Depending on the operating mode, this is a condenser or an evaporator. Switchable heat exchangers are often used, which supply a heating circuit as a condenser in winter and, after switching, as an evaporator, provide cooling air conditioning in the summer cause. Other functions include hot water generation and room air dehumidification. This means that such heat exchangers are subjected to a wide range of temperature differences and flows, which also change frequently. This alternating load leads to wear and, in rare cases, failure both within the heat exchanger and at the connecting connections.

Leaks of various sizes then occur, most of which are small and imperceptible. The safety refrigerants previously used then occasionally had to be refilled, which is no longer permitted due to the harmfulness of such safety refrigerants to the climate. For this purpose, these refrigeration circuits had service connections into which safety refrigerant could be refilled by a maintenance technician using a cartridge. Up to 70 percent of the safety refrigerant requirement was accounted for by such refilling processes.

In the case of flammable refrigerants, considerably greater effort must be made both during the initial filling, which only takes place at the installation site after installation, and when draining and refilling during repairs in order to prevent the formation of flammable mixtures at all times. An example here is this EP 3 026 374 B1 , the EP 3 062 044 B1 and the EP 2 985 550 A1 referred.

For times during operation, but also during downtimes, numerous technical advances have been made to encapsulate either the refrigerant lines or the heat exchanger of the indoor unit and to ensure that refrigerant that escapes through leaks is collected and safely removed from the installation building. It is common practice for flammable refrigerants that have a low impact on the climate to be discharged from the building in which they are installed to the outside. A strong dilution then takes place there and the mixture can no longer ignite once the ignition limits are exceeded.

You then want to repair the defect or dismantle and replace the defective parts. This is problematic because when the housing or encapsulation is opened, flammable gas could still be within the area to be opened or could flow in uncontrollably due to the remaining leakage. Before opening, ensure that no flammable gas mixture can escape.

The FR 3 070 755 A1 and the WO 03/010473 A1 each describe an indoor unit and/or an outdoor unit, with vents for flammable refrigerants being provided through the house wall, for example by means of a double-walled pipe, so that fresh air can enter when the inner housing is flushed.

The EP 3358272 B1 describes a housing for a water heat exchanger through which a flammable refrigerant flows. A special feature is an inner cover element which is arranged in the housing in order to cover at least one refrigerant line section of a refrigerant circuit and to direct an escaping refrigerant to an outside of the capsule housing, this cover element including a guide section which is connected to a connection opening to which the escaping refrigerant is connected Refrigerant is conducted. However, the cover is not an encapsulation of the entire water heat exchanger, but rather just a cover for the refrigerant connections. The refrigerant is therefore withdrawn from the cover, which only covers the refrigerant connections, and not from a capsule housing of the condenser. The cover does not completely encapsulate the capacitor.

The task is therefore to provide a safe and inexpensive method for safely ventilating and flushing encapsulated housings of installations that carry flammable refrigerant. Above all, these can be heat pump housings or encapsulated ones Parts of heat pumps such as evaporators, condensers, throttle valves, compressors and connecting lines. The process should be suitable for heat pumps installed indoors as well as for the internal parts of split heat pumps.

Heat pump housings include all housing parts in which devices are arranged that carry refrigerant or could lead in the event of a leak. This takes into account the fact that a large number of encapsulations are common. The heat exchangers can have separate housings, as can the control electronics with their cooling, the entire refrigeration circuit can be located in one housing, housings can be separate from ventilation devices or housings that are connected to outdoor units or housings that are nested inside one another. Be heat pump housing in the sense of this invention.

In the event of service or repairs, the refrigeration circuit must be accessible from all sides. This applies to all housings or enclosures that are connected to the refrigeration circuit, so that in case of doubt, all parts that may be affected by leaks are accessible. This creates a dilemma. If there is a leak, a flammable mixture of refrigerant and air could already have formed inside the respective housing. Methods of opening the housing that carry the risk of sparking cannot then be used.

The resulting problems have been known for a long time. That's how she teaches WO 2015/032905 A1 that a generator for electrical current is integrated into the opening or its locking of this room and, when activated, in a first step generates and provides the electrical energy with which a sensor is activated and which then does not release the locking in the event of an alarm, but rather causes the closed room to be ventilated and only allows unlocking and opening in a second step.

• das Gehäuse einen, durch ein Adsorbens für Arbeitsfluid geschützten, offenen Gasweg zur Umgebung aufweist,
• das Gehäuse eine Serviceöffnung besitzt, die durch eine Entriegelungsvorrichtung gegen Öffnen geschützt ist,
• die Serviceöffnung einen Serviceanschluss für eine Servicepatrone aufweist,
• die Servicepatrone ein unter Druck stehendes Inertgas in einer Menge enthält, welches im entspannten Zustand mindestens dem Volumen des Behälters entspricht,
• die Servicepatrone einen Patronenhals mit einer Verbindungsleitung im Patronenhals und einem Außengewinde auf dem Patronenhals aufweist,
• der Serviceanschluss ein Innengewinde besitzt, welches zu dem Außengewinde des Patronenhalses passt,
• der Serviceanschluss eine Verschlusskappe aufweist, wobei
  • die Verschlusskappe ein zur Außenseite des Gehäuses gerichtetes Dichtsiegel umfasst,
  • ferner eine zur Innenseite des Gehäuses gerichtete Dichtmembran, auf der ein Dorn in Richtung zur Außenseite des Gehäuses angeordnet ist,
  • ferner eine Dichtfläche auf dem Innengewinde.

The EP 3 705 823 B1 describes a device for safe service intervention for a housing and a method for opening a housing for a heat pump. The heat pump is an indoor heat pump that is open to the building via an activated carbon filter. It is provided on the housing, in which there is a flammable working fluid of a left-hand rotating cycle, that

• the housing has an open gas path to the environment protected by an adsorbent for working fluid,
• the housing has a service opening that is protected against opening by an unlocking device,
• the service opening has a service connection for a service cartridge,
• the service cartridge contains a pressurized inert gas in an amount which, in the relaxed state, corresponds at least to the volume of the container,
• the service cartridge has a cartridge neck with a connecting line in the cartridge neck and an external thread on the cartridge neck,
• the service connection has an internal thread that matches the external thread of the cartridge neck,
• the service connection has a closure cap, wherein
  • the closure cap comprises a sealing seal directed towards the outside of the housing,
  • furthermore a sealing membrane directed towards the inside of the housing, on which a mandrel is arranged towards the outside of the housing,
  • also a sealing surface on the internal thread.

However, if it is neither possible nor sensible to use an adsorber for a protected, open gas path in an interior, a different type of intervention is required, with parts of the technical teaching of EP 3 705 823 B1 can find use. This concerns encapsulated housings of devices in the event of leaks Refrigerant can enter and, above all, encapsulated inner housings of split devices, which are difficult to access from the outside. An output is then required for this refrigerant that escapes due to a leak, which changes the corresponding procedure for the service intervention accordingly.

As long as the leak exists and refrigerant can continue to escape, it is not possible to shut off the pipeline and disconnect the inner housing from all other installations and remove it for repair and then take it away. Pressure would then continue to build until the internal pressure of the refrigerant circuit and the pressure within the encapsulated inner housing have equalized. Depending on the inventory of remaining refrigerant and air within the encapsulated inner housing, first an ignitable mixture and then a mixture above the ignition limit would quickly form. When the capsule is opened, an ignitable mixture could immediately form due to the ingress of air and a deflagration could occur.

The object of the invention is therefore to provide an economical process that no longer has the disadvantages described. This task is solved by means of a service connection for an encapsulated inner housing in a heat pump housing, the encapsulated inner housing being referred to below as a capsule.

• die Kapsel mindestens ein Teil des Kältemittelumlaufs umfasst und
• die Kapsel einen Anschluss für eine Leitung aufweist, welche von der Kapsel ins Freie führt, aufweisend
• einen Serviceanschluss, der über eine Rückflusssperre verfügt,
• der Serviceanschluss das Innere der Kapsel mit ihrem Außenraum verbindet, wobei
• im Falle einer Leckage ein Inertgas oder eine inerte Flüssigkeit durch den Serviceanschluss in das Innere der Kapsel geleitet wird,
• und das Inertgas oder die inerte Flüssigkeit das entzündliche Luft-Gasgemisch des Inneren der Kapsel verdrängt und durch die Leitung, die ins Freie führt, wegleitet.

In particular, the task is solved by a method for inerting a capsule within a heat pump housing, the heat pump being operated with a flammable refrigerant, and

• the capsule comprises at least part of the refrigerant circulation and
• the capsule has a connection for a line which leads from the capsule to the outside
• a service connection that has a non-return valve,
• the service connection connects the interior of the capsule with its exterior, whereby
• In the event of a leak, an inert gas or an inert liquid is passed through the service connection into the interior of the capsule,
• and the inert gas or liquid displaces the flammable air-gas mixture of the interior of the capsule and directs it away through the line leading to the outside.

The capsule in the heat pump housing affects all encapsulations of devices that carry refrigerant and which prevent flammable refrigerant that escapes due to leakage from entering the installation room. The capsule also includes safety valves in the working fluid circulation and its discharge lines. In contrast to the teaching of EP 3 705 823 B1 The capsule can also be flooded with liquid that could not be passed into an adsorber. The extent to which such a liquid-filled capsule can be dismantled and transported away depends on its size and weight. In the case of a split device, it can be provided that only the heat exchanger, which can be affected as a condenser or evaporator inside the building, has to be filled accordingly, provided it is encapsulated is executed.

In one embodiment, it is provided that inert fluid, i.e. either inert gas or inert liquid or a mixture thereof, is initially introduced into the capsule through the service connection, and the concentration of the refrigerant is continuously measured. The measurement can take place within the encapsulation or at the connection of the Line that leads to the outside or in the line itself or at the outlet of the line to the outside. Such measurements are known state of the art and can be carried out automatically or, in individual cases, manually.

Of course, it makes sense if the flow of refrigerant to the relevant leak point is interrupted. Either this is done using shut-off valves in the refrigeration circuit or the refrigerant is extracted separately from the refrigeration circuit using known means. As soon as the capsule is inerted and no further coolant flows in, one embodiment provides that the line is closed to the outside and the capsule is removed. It can then be opened safely.

In one embodiment it is provided that the capsule is filled with water via the service connection and rinsed. This is advantageous if there is only a small amount of inert gas available, but enough water is available, and this water can also drain out into the open via the pipe. To remove the water, compressed air can also be used via the service connection.

• die Kapsel mindestens ein Teil des Kältemittelumlaufs umfasst und
• die Kapsel einen Anschluss für eine Leitung aufweist, welche von der Kapsel ins Freie führt, und
• der Serviceanschluss das Innere der Kapsel mit ihrem Außenraum verbindet und über eine Rückflusssperre verfügt.

The invention also solves the problem by means of an adapted service connection for an encapsulated heat pump housing, whereby

• the capsule comprises at least part of the refrigerant circulation and
• the capsule has a connection for a line which leads from the capsule to the outside, and
• the service connection connects the inside of the capsule with its outside and has a non-return valve.

In one embodiment it is provided that the service connection of the capsule is connected to the outside space via an extension line. This is particularly advantageous if the capsule is located inside a heat pump housing. The service connection can then be placed through the outer wall of the heat pump housing and operated from the outside. The heat pump housing then does not have to be opened in order to inert and rinse the capsule inside.

In further refinements it is intended to provide several service connections. These can be tailored to different inerting and rinsing media, for example, nitrogen, carbon dioxide and water. In the case of nitrogen, a heating device may be provided to counteract freezing due to the Joule-Thomson effect when the pressure of the nitrogen is reduced.

In a further embodiment, it is provided that the capsule includes all installations of the refrigeration circuit that carry refrigerant; in the case of split devices, all installations that are located within a building. In the event of a leak, refrigerant can also get into the heating circuit water. In a further embodiment, it is therefore provided that the heating circuit is equipped with a safety valve, which blows out into the capsule via a line if the pressure in the heating circuit rises impermissibly and there is a fear that this increase in pressure is the result of a leak from a device under higher pressure refrigerant.

Furthermore, in a further embodiment it is provided that the heating circuit is equipped with an automatic vent, which vents into the capsule via a line. This means that both small and large amounts of refrigerant that have leaked into the heating circuit water are returned to the capsule and from there discharged from the capsule into the open air.

• Fig. 1 eine schematische Darstellung einer Kapsel mit einem WärmepumpenKondensator,
• Fig. 2 eine schematische Darstellung einer Kapsel in einer Innenbox,
• Fig. 3 eine schematische Darstellung einer Kapsel in einer Kompaktwärmepumpe,
• Fig. 4 eine schematische Darstellung einer Kapsel in einer Innenbox mit Sicherheitsventil und automatischem Entlüfter.

The invention is based on Fig. 1 to Fig. 4 explained in more detail. Show it:

• Fig. 1 a schematic representation of a capsule with a heat pump condenser,
• Fig. 2 a schematic representation of a capsule in an inner box,
• Fig. 3 a schematic representation of a capsule in a compact heat pump,
• Fig. 4 a schematic representation of a capsule in an inner box with a safety valve and automatic vent.

Fig. 1 shows a schematic representation of a capsule 1 with a heat pump condenser 2. The refrigerant supply line 3, the refrigerant return line 4, the heating circuit supply line 5, the heating circuit return line 6 and the ventilation line 7 lead into the capsule 1. The capsule is equipped with a service connection 8, whereby this has a non-return valve and a holder for a gas cartridge. The cartridge 9 can be connected directly to this service connection 8 with a connecting piece 10. The capsule 1 can then be flushed with the gas from the cartridge 9, for example carbon dioxide or nitrogen, until the measuring device 11 on the vent line 7 indicates that no more refrigerant is flowing into the capsule 1.

Fig. 2 shows capsule 1 Fig. 1 , installed in an indoor unit 12 of a split heat pump 13, in which the refrigerant is passed through both the indoor unit and the outdoor unit. The latter has an outer box 14, which contains the evaporator 15, the compressor 16 and the throttle valve 17, as well as the air duct 18 and the fan 19 as a heat source. The refrigerant supply line 3 and the refrigerant return line 4 are connected to the refrigeration circuit of the outer box 14, the ventilation line 7 However not. The ventilation line leads through the outer wall 20 to the outside, preferably the opening is just above the top of the capsule 1. This makes it easier to rinse with water if necessary.

Fig. 3 shows the case in which the entire refrigeration circuit of an internally installed compact heat pump 21 is arranged within a capsule 1. About those in the Fig. 1 and Fig. 2 A further service connection 22 with an extension 23, which is guided through the housing wall 24, is provided. This means that the inerting and subsequent rinsing with water or compressed air can take place without opening the heat pump housing of the heat pump 21.

Fig. 4 shows in addition to that in Fig. 2 The arrangement shown includes the integration of a safety valve 25 and a breather 26, both of which are provided in the heating circuit line 6 in the event that refrigerant has gotten into the heating circuit water due to a leak. If pressure builds up in the heating circuit due to the leak, the safety valve 25 opens and blows into the capsule 1. Remaining gas bubbles are separated by the breather 26, even in the event that the safety valve 25 has not been triggered because only a small amount of refrigerant has escaped. The separated gas is also vented into the capsule 1. The heating circuit water is subsequently further heated by the electric additional heater 27.

Reference symbol list

1

capsule

2

Heat pump condenser

3

Refrigerant supply line

4

Refrigerant return line

5

Heating circuit supply line

6

Heating circuit return line

7

vent line

8th

Service connection

9

cartridge

10

connector

11

measuring device

12

Indoor unit

13

Split heat pump

14

Outer box

15

Evaporator

16

compressor

17

Throttle valve

18

Air duct

19

Fan

20

external wall

21

Compact heat pump

22

additional service connection

23

Extension cable

24

housing wall

25

Safety valve

26

ventilator

27

Electric additional heater

Claims (10)

Method for inerting an encapsulated heat pump housing by means of a service connection, the heat pump being operated with a flammable refrigerant, and - The capsule (1) comprises at least part of the refrigerant circulation (2, 15,16,17).
and - The capsule (1) has a connection for a line (7) which leads from the capsule to the outside - a service connection (8), which has a non-return valve, and - the service connection (8) connects the interior of the capsule (1) with its exterior,
characterized in that - in the event of a leak, an inert gas or an inert liquid is passed through the service connection (8) into the interior of the capsule (1), - And the inert gas or the inert liquid displaces the flammable air-gas mixture from the interior of the capsule (1) and leads it away through the line (7), which leads to the outside. Method according to claim 1, characterized in that inert fluid is first introduced into the capsule (1) through the service connection (8), and the concentration of the refrigerant is continuously measured, the measurement (11) taking place inside the capsule (1) or on Connection of the line (7) that leads to the outside or in the line (7) itself or at the outlet of the line (7) to the outside. Method according to claim 2, characterized in that the line (7) is closed to the outside and the capsule (1) is removed as soon as the capsule (1) is inerted and no further coolant flows in, Method according to one of claims 1 to 3, characterized in that the capsule (1) is filled with water or compressed air after inerting and rinsed. Service connection (8) for an encapsulated heat pump housing, characterized in that - the capsule (1) comprises at least part of the refrigerant circulation and - the capsule (1) has a connection for a line (7) which leads from the capsule (1) to the outside, and - The service connection (8) connects the inside of the capsule (1) with its outside and has a non-return valve. Service connection (8) according to claim 5, characterized in that the service connection (8) of the capsule (1) is connected to the outside space via an extension line (23). Service connection according to claim 6, characterized in that the extension line (23) of the service connection (8) of the capsule (1) is laid through the outer wall (24) of the heat pump housing. Device according to one of claims 5 to 7, characterized in that several different service connections (8) are provided. Device according to one of claims 5 to 8, characterized in that the capsule (1) encloses all installations carrying refrigerant. Device according to one of claims 5 to 9, characterized in that the capsule (1) is connected to heating circuit lines and a blow-off line of a safety valve (25) of a heating circuit line and/or the vent line of a vent (26) of a heating circuit line into the capsule (1) be guided.

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