DE102015122681A1 - Safety heat exchanger for a climate system with flammable and / or toxic refrigerant - Google Patents

Abstract

The invention relates to a heat exchanger (9) for an air conditioning system, comprising at least one refrigerant pipe (20) extending through an air duct (L) and a safety pipe (26) surrounding the refrigerant pipe within the air duct. The invention also relates to an air conditioning system with a compressor (1), an ambient air heat exchanger and such a room air heat exchanger (9).

Description

The invention relates to a safety heat exchanger for an air conditioning system and an air conditioning system with such a heat exchanger.

In particular, the invention relates to a so-called air conditioner, which is suitable for cooling the interior of caravans, boats, etc. The invention can also be used for room air conditioning of apartments or buildings.

Such air conditioners are for example from the WO 2007/042065 A1 known. Their function is described below on the basis of 1 explained.

A compressor 1 compresses a gaseous refrigerant, which via a refrigerant line 2 to an ambient air heat exchanger 3 which is a condenser when the air conditioner is used for cooling room air. In the ambient air heat exchanger 3 condenses the refrigerant by a part of the heat stored in it is released into the ambient air. This is an ambient air blower 4 provided the air through an inlet 5 sucks and over an outlet 6 to the environment.

The in the ambient air heat exchanger 3 liquefied refrigerant is supplied via a coolant line 7 to an expansion device 8th guided, for example, a throttle.

When you relax the refrigerant goes into the vapor state. At the same time, the temperature of the refrigerant decreases. The expanded refrigerant is placed in an air conditioning heat exchanger 9 introduced, which works as an evaporator, when the air conditioner is used for cooling room air.

The room air for the room to be air-conditioned is through the room air heat exchanger 9 directed. For this purpose, a room air blower 10 be used, which the room air through an air inlet 11 sucks, through the room air heat exchanger 9 leads and via one or more room air outlets 12 back to the room to be aired.

In the room air, through the room air heat exchanger 9 It can be fresh air, air taken from the room to be air-conditioned, or a mixture of them.

From the room air heat exchanger 9 the refrigerant is passed through a refrigerant line 14 returned to the compressor, where it is compressed again.

This air conditioning system can be used not only as an air conditioner for cooling room air, but also as a heat pump for heating room air.

The refrigerants used are usually so-called safety refrigerants (for example R134a), ie refrigerants based on halogenated hydrocarbons. From an environmental point of view, there has recently been an increasing desire to use refrigerants with a low global warming potential, for example propane or R32. However, since propane and R32 are flammable, they can not be used in a conventional air conditioner for safety reasons.

The object of the invention is to provide an air conditioning system in which combustible and / or toxic refrigerants can be used.

To achieve this object, a heat exchanger for an air conditioning system is provided according to the invention, with at least one refrigerant pipe which extends through an air duct, and at least one safety tube which surrounds the refrigerant pipe within the air duct. The safety pipe ensures that in the event of a leak, the refrigerant can not enter the air duct and from there into the room to be air-conditioned, but is caught by the safety pipe. In this way, a safety heat exchanger is provided in which flammable and / or toxic refrigerants can be used without the risk, in the event of leakage, that escaping refrigerant passes through the air in rooms in which people are present. Thus, no dangerous (combustible and / or toxic) air mixtures can form there.

According to one embodiment of the invention, it is provided that the safety tube outside the air duct is open to the environment. Thus, the refrigerant can, if it comes to a defect, are selectively discharged to an area outside of the room to be air conditioned.

In principle, according to an alternative embodiment, it is also conceivable that the safety tube ends in a closed system to which a sensor is assigned. This will respond if there is refrigerant in the containment tube.

According to a preferred embodiment it is provided that the safety pipe and the refrigerant pipe are in good heat-conducting connection. In this way, a good heat transfer from the refrigerant through the refrigerant pipe and the safety tube is ensured on the air flowing through the air duct, to be cooled.

It is preferably provided that the safety tube and the refrigerant tube abut each other. This results in a good heat transfer by heat conduction.

According to one embodiment of the invention it is provided that the safety tube is roughened on its inside and / or the refrigerant tube on its outside. It can also be provided that the safety tube is provided on its inside and / or the refrigerant tube on its outside with at least one discharge channel. By means of the surface roughness or the discharge channel it is ensured that the refrigerant can be led out laterally out of the area between the safety pipe and the refrigerant pipe in the event of a leak.

The discharge channel may be formed by at least one groove or groove in the outer surface of the refrigerant tube and / or the inner surface of the safety tube. The discharge channel can also be formed by different geometries and / or surface textures of the outer surface of the refrigerant tube and the inner surface of the safety tube, for example, a slightly oval refrigerant tube, which is arranged in a round safety tube, or vice versa.

Preferably, it is provided that the air duct is delimited by outer walls (so-called "endplates") through which extend a plurality of refrigerant tubes through which the refrigerant can flow, and that the surrounding the refrigerant tubes safety pipes outside the air duct are open to the environment. In this embodiment, a mechanically simple structure results.

Preferably, the safety tube communicates with heat transfer ribs. The heat transfer fins increase the surface area available for transferring heat from the air flowing through the air flow passage to the refrigerant.

In order to ensure a good heat-conducting connection between the safety tube and the refrigerant tube, it can be provided that the refrigerant tube and the safety tube abut each other by means of a press fit. This can be achieved by selecting an outer diameter for the refrigerant tube that is suitably larger than the inner diameter of the safety tube and pushing the refrigerant tube into the safety tube. In this case, the safety tube can be widened, so that there is a good heat-conducting connection with previously deferred heat transfer ribs.

The interference fit can also be obtained by heating the safety tube and / or cooling the refrigerant tube before the tubes are assembled together. It is also possible to set the refrigerant tube, after it has been placed inside the safety tube, under a high internal pressure, so that it widens and thereby plastically deforms.

It can also be provided that the refrigerant pipe and the safety pipe are made in one piece with each other. As a result, separation points are avoided, which would be detrimental to the heat conduction.

According to one embodiment, it is provided that the refrigerant tube and the safety tube are sections of an extruded profile part. In this way, the two tubes can be made in good heat conducting connection and with the desired geometry.

According to one embodiment of the invention, it is provided that a good heat-conducting material is arranged between the refrigerant tube and the safety tube, which defines at least one gas conduit. The highly thermally conductive material may be, for example, a porous material through which any escaping refrigerant is passed. As a good heat conducting material, for example, graphite can be used.

To achieve the above object, an air conditioning system with a compressor, an ambient heat exchanger and a room air heat exchanger of the aforementioned type is provided according to the invention. With regard to the resulting advantages, reference is made to the above explanations.

The invention will be described below with reference to various embodiments, which are illustrated in the accompanying drawings. In these show:

1 schematically a refrigerant circuit;

2 in a partially sectioned plan view of an air conditioning system;

3 in a schematic, perspective view of a heat exchanger according to the invention;

4 in a schematic sectional view of a part of a heat exchanger according to the invention;

5 on an enlarged scale the section V of 4 ;

6 a portion of a refrigerant tube according to an alternative embodiment; and

7 in a schematic sectional view of another embodiment of a refrigerant pipe with safety tube.

In 2 is an inventive air conditioning system with a safety heat exchanger according to the invention 9 shown.

The room air heat exchanger 9 has a variety of refrigerant tubes 20 on, extending between opposite outer walls 22 of the heat exchanger extend. Several of the individual refrigerant pipes 20 are by means of pipe bends 24 connected in series (see also 3 ). Depending on the desired operating mode, all refrigerant pipes can be connected in series (single-flow operation), or packages of series-connected refrigerant pipes can be connected in parallel (multi-flow operation).

Between the outer walls 22 and through the area in which the refrigerant tubes are located is defined a room air duct L through which the room air flows, which communicates with the room air heat exchanger 9 to be air conditioned.

The refrigerant pipes 20 extend through the outer walls 22 to outside the area of the air duct between the outer walls 22 , Thus are also the solder joints, by means of which the pipe bends 24 with the refrigerant pipes 20 are connected, outside the air duct.

The outer walls 22 of the heat exchanger 9 are here tight in a sidewall 15 a housing 16 of the climate system. This is also a seal 17 intended. In this way is a room air area 18 close to an ambient air area 19 separated.

Every refrigerant pipe 20 is from a safety tube 26 surround. The safety pipes 26 also extend through the outer walls 22 , As in particular in the 3 and 4 can be seen, are the ends of the safety tubes 26 outside the outer walls 22 open. The passage of the safety tubes 26 through the outer walls is executed sealed. Thus, the safety tubes 26 to the ambient air area 19 open and from the room air area 18 hermetically isolated.

The refrigerant pipes 20 stand with the safety tubes 26 in a good heat-conducting connection. Unlike in the schematic representation of 4 shown, lies the outer surface of the refrigerant tubes 20 on the inner surface of the safety tubes 26 on (see 5 ).

To ensure that refrigerant, in case of leakage from the refrigerant pipe 20 escapes, in the axial direction between the refrigerant pipe 20 and the safety tube 26 in the ambient air area 19 can be removed, are between the refrigerant pipe 20 and the safety tube 26 suitable designs provided. An example is a spirally revolving discharge channel 28 as he is in 5 shown, or one or more longitudinally extending discharge channels.

At the in 5 The example shown is the discharge channel 28 in the outer surface of the refrigerant pipe 20 intended. It is just as possible that the discharge channel 28 on the inner surface of the safety tube 26 is provided.

An alternative embodiment is in 6 shown. There is the refrigerant pipe 20 on its outside with a Kreuzrändelung 30 Mistake. The Kreuzrändelung ensures that very fine flow channels between the outside of the refrigerant pipe 20 and the inside of the safety tube 26 are present, even if the inside of the safety tube 26 firmly on the outside of the refrigerant pipe 20 is applied.

On the safety tubes 26 are in a conventional manner a plurality of heat transfer fins 32 put on, the whole a ribbed package 34 form.

For a good heat transfer from the refrigerant through the refrigerant pipe 20 on the safety tube 26 and from there to the heat transfer ribs 32 It is important to have a good heat conducting connection between the refrigerant pipe 20 and the safety tube 26 is established. For this purpose, the outer surface of the refrigerant pipe is located 20 firmly on the inner surface of the safety tube 26 at.

The desired intimate contact can be achieved, for example, by first having a refrigerant pipe 20 is provided with an outer diameter which is slightly smaller than the inner diameter of the safety tube 26 is. After the two tubes are plugged into each other, the refrigerant pipe 20 so widened that it is firmly attached to the inner surface of the safety tube 26 is applied.

For this purpose, within the refrigerant pipe 20 a high pressure is built up, which is the refrigerant pipe 20 expands and thereby plastically deformed. The properties of the two tubes are matched to each other so that when Expansion of the refrigerant pipe 20 there sets a suitable plastic deformation, taking into account the inevitable springback when the internal high pressure is reduced, the desired close mechanical contact between the outside of the refrigerant pipe 20 and the inside of the safety tube 26 leads.

According to a further embodiment it can be provided that the safety tube is suitably heated and / or the refrigerant tube 20 is suitably cooled before the tubes are pushed into each other. If the tubes then have their starting temperature again, the desired mechanical contact between the refrigerant tube results due to the thermal expansion 20 and the safety tube 26 ,

It can also be used two tubes between which an annulus remains. This is filled with a good heat-conducting material, which also allows a gas throughput, for example due to porosity. A suitable material is graphite, for example.

In 7 another embodiment is shown in which the safety tube 26 the outer portion of an extruded profile part 40 and the refrigerant pipe 20 represents the inner section. The refrigerant pipe 20 and the safety tube 26 are here by footbridges 42 connected together, so that there is a good heat conduction from the refrigerant pipe 20 to the safety tube 26 results.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2007/042065 A1 [0003]

Claims (14)

Heat exchanger ( 9 ) for an air conditioning system, with at least one refrigerant pipe ( 20 ), which extends through an air duct (L), and a safety tube ( 26 ), which surrounds the refrigerant pipe within the air duct. Heat exchanger ( 9 ) according to claim 1, characterized in that the safety tube ( 26 ) is open to the environment outside the air duct (L). Heat exchanger ( 9 ) according to claim 1 or claim 2, characterized in that the safety tube ( 26 ) and the refrigerant pipe ( 20 ) are in good heat conducting connection. Heat exchanger ( 9 ) according to one of the preceding claims, characterized in that the safety tube ( 26 ) and the refrigerant pipe ( 20 ) abut each other. Heat exchanger ( 9 ) according to one of the preceding claims, characterized in that the safety tube ( 26 ) on its inside and / or the refrigerant pipe ( 20 ) is roughened on its outside. Heat exchanger ( 9 ) according to one of the preceding claims, characterized in that the safety tube ( 26 ) on its inside and / or the refrigerant pipe ( 20 ) on its outside with at least one discharge channel ( 28 ) is provided. Heat exchanger ( 9 ) according to one of the preceding claims, characterized in that the air duct (L) by outer walls ( 22 ) is delimited, through which several refrigerant tubes ( 20 ), through which the refrigerant can flow, and that the refrigerant pipes ( 20 ) surrounding safety tubes ( 26 ) are open to the environment outside the air duct (L). Heat exchanger ( 9 ) according to one of the preceding claims, characterized in that the safety tube ( 26 ) with heat transfer ribs ( 32 ). Heat exchanger according to one of the preceding claims, characterized in that the refrigerant pipe ( 20 ) and the safety tube ( 26 ) abut each other by means of a press fit. Heat exchanger according to one of claims 1 to 8, characterized in that the refrigerant pipe ( 20 ) and the safety tube ( 26 ) are made in one piece with each other. Heat exchanger according to claim 10, characterized in that the refrigerant pipe ( 20 ) and the safety tube ( 26 ) Are sections of an extruded profile part. Heat exchanger according to one of the preceding claims, characterized in that between the refrigerant pipe ( 20 ) and the safety tube ( 26 ) a good heat conducting material is arranged, which defines at least one gas duct. Heat exchanger according to claim 12, characterized in that the good heat-conducting material is porous, for example graphite. Air conditioning system with a compressor ( 1 ), an ambient air heat exchanger and a room air heat exchanger ( 9 ) according to any one of the preceding claims.

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