WO2013017439A1

WO2013017439A1 - Desorber for an air conditioning device

Info

Publication number: WO2013017439A1
Application number: PCT/EP2012/064272
Authority: WO
Inventors: Emmanuel Boudard; Florian Kervarec; Werner Zimmermann; Peter Binneberg
Original assignee: Peugeot Citroen Automobiles Sa; Webasto Ag
Priority date: 2011-08-03
Filing date: 2012-07-20
Publication date: 2013-02-07

Abstract

The invention relates to a desorber (100) for a device for air conditioning by absorption, especially for a motor vehicle, comprising a housing (110) containing at least one constituent of the desorber, including a heat exchanger (7), a mixture of absorbent fluid and refrigerating fluid being introduced into the housing (110), in contact with the heat exchanger (7). The invention is characterised in that the system for distributing the mixture of absorbent and refrigerating fluids is built into the upper wall of the housing (110).

Description

DISORBER OF AN AIR CONDITIONING DEVICE

The present invention relates to an air conditioning device by absorption. It relates more particularly to the desorber of such an air conditioning device.

The invention also relates to a motor vehicle, equipped with such an improved absorption air conditioning device.

Among the existing air conditioning devices, there are known air conditioning devices by absorption, based on the principle of the absorption of a refrigerant fluid, in gaseous form, by an absorbent fluid. Unlike conventional mechanical compression air-conditioning devices, these non-mechanical absorption air-conditioning devices have few moving parts, which reduces noise and vibration, simplifies maintenance, and improves reliability and durability. of the device.

We have already sought to improve the performance of air conditioning devices by absorption to be able to implement them easily and reliably in vehicles. Such air conditioning devices must, however, be further improved to be implemented effectively in motor vehicles.

Thus, the volume of existing absorption air conditioning devices remains relatively large, and it is necessary to reduce it to effectively adapt such a system in the reduced space of a vehicle.

Moreover, it is necessary to minimize the cost of the elements of these air conditioning devices. For this, it is necessary to simplify these elements to the maximum.

The object of the present invention is therefore to provide an absorption air conditioning device adapted to motor vehicles, which is improved in its operation with respect to known air conditioning or absorption cooling devices of the prior art.

In particular, an object of the present invention is to provide such an absorption air conditioning device that allows to offer the same performance with a reduced volume compared to the devices of the prior art.

Another object of the present invention is to provide such an absorption air conditioning device, which is simple in design and whose implementation requires inexpensive technological means. These objectives, as well as others which will appear more clearly later, are achieved by a desorber for an air conditioning device by absorption, in particular for a motor vehicle, comprising a housing in which are housed one or more components of the desorber, among which a heat exchanger, a mixture of absorbent fluid and refrigerant fluid being introduced into the casing, in contact with the heat exchanger (7), characterized in that the distribution system of the mixture of absorbing fluids and refrigerant is integrated in the upper wall of the housing forms a distribution system of the mixture of absorbent fluids. By integrated is meant that the upper wall itself constitutes this distribution system or an attached distribution system is fixed inside the upper wall of the housing.

[001 1] Integrating the distribution system of the fluid mixture to the upper wall reduces the total cost of the device, the inherent rigidity of the fluid distribution system reinforcing the housing to limit the forces to be supported by the housing.

In a preferred embodiment, this distribution system is supported on the heat exchanger housed in the housing, so that the rigidity of the housing is increased. To ensure a significant increase in rigidity, the support must not be punctual or localized in a limited area but instead be performed in a large number of points to balance the loads on the entire upper face of the heat exchanger.

In a variant, the dispensing system is constituted by a plurality of grooves forming channels defined in said upper wall, the bottom of these channels (1 1 1) having holes to allow flow in the casing of the fluids present in the channels. Preferably, these channels are shaped to form a corrugated structure reinforcing the rigidity of the housing.

In a variant, the heat exchanger comprises exchange plates extending vertically, and said channel grooves are oriented parallel to the upper edges of these exchange plates.

In a variant, said grooves forming channels are oriented in the direction of flow of the steam produced in the desorber, to facilitate this flow.

In a variant, the desorber further comprises a cover placed above the upper wall of the casing, to form a fluid reservoir between the cover and the upper wall.

In a variant, the casing has moreover at least one of these other walls in direct or indirect support against the heat exchanger, which further enhances the rigidity of the casing. [001 8] Thus, a spacer can be placed between at least one side face of the heat exchanger and the corresponding wall of the housing, said spacer being preferably formed by a folded plate of the same material as the heat exchanger .

Alternatively, or in addition, the bottom wall of the housing may have a plurality of ribs in contact with the heat exchanger, these ribs being preferably oriented in the direction of flow of the fluid after it passes into contact with the heat exchanger. exchanger.

The present invention also relates to an air conditioning device for absorption, in particular for a motor vehicle, comprising a desorber as described above, and a motor vehicle comprising such an air conditioning device.

Other objects, advantages and features of the invention will appear in the following description of preferred embodiments, not limiting the object and scope of the present patent application, accompanied by drawings in which:

Figure 1 shows schematically the principle of operation of an air conditioning device by absorption;

Figure 2 shows schematically the functional circuit of an air conditioning device by absorption;

Figure 3 shows, schematically, the desorber of an air conditioning device by absorption;

FIG. 4 is a cutaway perspective view of a desorber according to one embodiment of the invention;

Figure 5 is a partial section of the desorber of Figure 4, showing the top thereof;

Figure 6 is a partial section of the desorber of Figure 4, showing the bottom thereof;

Figure 7 shows the heat exchanger of the desorber of Figure 4;

Figure 8 shows a plate of a heat exchanger of a desorber according to another possible embodiment of the invention.

An absorption air conditioning device implements a double fluid circuit, one carrying a refrigerant fluid, for example water, and the other an absorbent fluid, for example a lithium bromide salt solution. (LiBr). These two fluids are miscible, and part of the circuits is common to both circuits and carries a mixture of coolant and absorbent fluids.

Figure 1 shows schematically the constituent elements and the operating principle of an air conditioning device by absorption. It includes a element in which the desorption is carried out, designated "desorber" 100 in the rest of the text, a condenser 200, an evaporator 300 and an absorber 400.

The desorber 100 and the absorber 400 are filled with a mixture of at least two miscible substances formed by the coolant and the absorbent fluid. This mixture is combined in the absorber 400, wherein the absorbent fluid absorbs the coolant.

The refrigerant and the absorbent fluid have sufficiently different evaporation pressures so that, when the mixture is heated in the desorber 100, the refrigerant fluid, more volatile, evaporates, allowing the separation of the two fluids. The heat necessary for this separation (contribution illustrated schematically by the arrow A) can advantageously be provided to the desorber by the engine coolant of the vehicle.

The refrigerant in the form of steam is then fed through the pipe 20 in the condenser 200 to be condensed by the cooling action of the outside air (cooling contribution schematically illustrated by the arrow B).

The coolant in the liquid phase is then fed through the pipe 10 to the evaporator 300. The cold produced during the evaporation of this refrigerant fluid is transmitted to the passenger compartment of the vehicle (not shown), as schematically illustrated. by the arrow C. For this purpose, there is provided a pump 310 and a heater 320, which are connected to the evaporator 300 by the pipes 1 1, 12 and 13.

The coolant vapor leaving the evaporator 300 is fed into the absorber 400 through the conduit 21 which is formed by the envelope of the absorber / evaporator assembly. The absorbent fluid, which has been cooled by external air in the saline solution circuit (cooling supply schematically illustrated by the arrow D), then absorbs this water vapor to reform the mixture.

The saline solution circuit is formed by a pump 410 and a radiator 420, which are connected to the absorber 400 by the pipes 16, 17, 18 and 19. The absorber 400 is connected to the desorber 100 through the pipes. 14, 15 and 16.

[0030] Figure 2 shows the functional circuit of an absorption air conditioning to which the present invention can be applied. By way of non-limiting example, it is an absorption machine that uses the LiBr-water pair (lithium bromide as absorbent fluid and water as coolant).

Elements of the circuit identical or similar to elements of Figure 1 are designated, most often, by the same reference numeral. The references 100 and 200 respectively denote the desorber and the coolant condenser. The references 320 and 420 respectively denote the coolant heater and the radiator of the absorbent fluid.

The references 310 and 410 respectively denote the coolant circuit pump and the pump of the absorbent fluid circuit. References 350 and 450 respectively denote the refrigerant reserve and the absorbent fluid reserve. The references 62 and 63 designate check valves, and the reference 20 designates the pipe bringing the water vapor of the desorber 100 to the condenser 200.

The reference 500 designates an assembly that combines the absorber and the evaporator of the air conditioning device by absorption. In this evaporator / absorber assembly, traversed by a flow of refrigerant fluid and an absorbent fluid flow, a part of the refrigerant fluid is evaporated, and this evaporation reaction, endothermic, has the effect of cooling the flow of refrigerant remaining. The vapor produced is directly absorbed by the flow of absorbent fluid. Moreover, the heat produced by the exothermic absorption reaction is removed by the flow of absorbent fluid circulating in the block.

FIG. 3 schematically represents the desorber 100. This desorber 100 consists of a casing 1 10 in which an inlet 14 is opened for the mixture of absorbent fluid and refrigerant, an outlet 15 for the absorbent fluid, and a pipe 20 for discharging the refrigerant in the form of steam, leading to the condenser 200.

A heat exchanger 7 traversed by a hot fluid, for example the coolant from the engine of the vehicle, provides heat to the desorber 100. Thus, the mixture of absorbent fluid and refrigerant arriving through the inlet 14 is heated in contact with the exchanger 7, which causes evaporation of the refrigerant. After this evaporation, the absorbent fluid is recovered at the bottom of the casing 1 10 and out of the desorber 100 by the outlet 15. This operation is the desorption.

The casing 1 10 of the desorber 100 must withstand the pressure difference between the inside and outside of the desorber. The pressure inside this casing 1 10 corresponds ideally to the saturation vapor pressure of the refrigerant. In the case of a LiBr-water type air-conditioning, in which the coolant is water, the interior of the desorber 100 has a pressure of the order of 2 to 300 mbar. This pressure much lower than the external ambient pressure thus exerts on the casing 1 10 a force from the outside to the inside that can be up to 1 kg per cm ² . For example, on a face of 15 cm by 25 cm of this housing 1 10, or 375 cm ² , this effort can reach 375 kg. Such a force can cause significant deformations on a housing made of flexible materials, for example plastic or aluminum. It is possible to manufacture a casing 1 10 having a sufficient thickness to resist these forces, or having reinforcing ribs allowing it to have sufficient rigidity. However, these solutions have the disadvantage of increasing the volume and the weight of the desorber 100, and therefore the air conditioning system, to increase the amount of material needed to manufacture the casing 1 10 and to make its shape more complex, which increases its cost price.

Figure 4 is a cutaway perspective view of a desorber 100 according to one embodiment of the invention, which avoids these disadvantages of the prior art. Figures 5 and 6 are partial sections of this desorber, showing respectively the top and the bottom thereof. Figure 7 shows some of the elements of this desorber.

This desorber 100 comprises a housing 1 10 having a generally parallelepipedal shape whose longitudinal and transverse sections are rhombic. Thus, when the casing side walls 1 10 are vertical, the lower and upper walls of this casing 1 10 are inclined relative to the horizontal, which makes it possible to promote the flow of liquid on the bottom wall and the gas along the upper wall.

The casing 1 10 is open on one of its faces to allow mounting of the desorber elements. A cover 120 makes it possible to close this opening of the casing 1 10.

A heat exchanger 7 is placed inside the casing 1 10. This exchanger 7, which is shown without the casing in FIG. 7, consists of a plurality of exchange plates 71, extending vertically and in the direction of the length of the housing 1 10. The plates 71 are positioned parallel to each other, separated from each other by spacers 72 formed by thin sheets folded crenel. Each spacer thus forms a plurality of walls extending vertically and parallel to the plates 71, which allow gravity flow of the liquid to be heated along the plates 71.

Each of the exchange plates 71 comprises a plurality of substantially horizontal conduits 75 which are traversed by a hot fluid, for example the coolant from the vehicle engine. A distribution box 74 is placed at one end of the exchanger 7, and the cover 120 whose inner face forms the distribution box 121 is assembled at the other end of the exchanger 7. The inlet and the outlet of the hot fluid into the desorber is through this distribution box 121. These distribution boxes placed at the two ends of each of the plates, allow to ensure, in a manner known to those skilled in the art, the circulation in the hot fluid pipes.

The distribution system of the mixture of absorbent fluid and refrigerant on the exchanger 7 is relatively complex to achieve: this system must indeed evenly distribute a low mixing rate (about 30 to 300 L / h, for example, for a cooling device 6 kW of cooling capacity) on the exchanger 7, so that the exchange plates 71 of this exchanger 7 are fully wetted. The correct positioning of the dispensing system relative to the exchanger 7 is important. In addition, this distribution system must not hinder the evacuation of the gas generated by the evaporation of the refrigerant.

In the embodiment shown in Figures 4 to 7, the distribution system of the mixture on the exchanger 7 is formed in the upper wall of the housing 1 10. For this, grooves 1 1 1 forming channels are formed in this upper wall, and extend in the direction of the length of the casing 1 10 so as to be parallel to the upper edges of the exchange plates 71. This orientation of the grooves 1 1 1 allows them not to hinder the flow of refrigerant vapor to the opening 20.

As shown in Figure 5, the bottom of each of these channel grooves 1 1 1 is supported, over its entire length, on the upper edge of one of the plates 71. Thus, the upper wall of the casing 1 10 is stiffened by the grooves 1 January 1 and is also reinforced by its support on the plates 71, which opposes the deformation of this wall inwardly.

A cover 130 covers the portion of the upper wall of the casing 1 10 where are formed the grooves 1 1 1 so as to form a reservoir between the upper wall and the cover 130. The arrival 14 of mixture is made through this cover 130, so that this mixture fills the reservoir thus formed, and thus the channels formed by the grooves January 1. Holes 1 12 are drilled at the bottom of each of the channels formed by the channels 1 January 1, and distributed so as to allow the flow of the mixture on the plates 71. The number, the position and the diameter of these holes are chosen so that, during the normal operation of the air conditioning device, the mixing flow arriving in the desorber 100 is uniformly distributed on the plates 71.

To avoid the deformation of the cover 130, it is possible that it has, on its lower wall, a number of spacers bearing on the upper wall of the housing 1 10, which is itself reinforced by the presence of the grooves 1 1 1 and its support on the plates 71 of the exchanger 7.

At the bottom of the exchanger 7, as shown in Figure 6, the lower edges of some of the plates 71 are supported on ribs 1 13, formed on the inner face of the lower wall of the housing 1 10. From Advantageously, these ribs are oriented so as not to impede the flow of the absorbent fluid under the exchanger 7, after the evaporation of the refrigerant, to the outlet opening 15 of the absorbent fluid. The support of the exchanger 7 on the bottom wall of the housing 1 10 reinforces the bottom wall, avoiding its deformation under the effect of the pressure difference between the inside and outside of the housing 1 10. Figure 7 shows an assembly formed by the exchanger 7, the distribution box 74 and the lid 1 20 forming the distribution box 1 21. This assembly is intended to be assembled to the housing 1 10. The width of the housing 1 10 must be sufficient to introduce the distribution box 1 20, which is wider than the exchanger 7.

To allow the side walls of the casing 1 10 to bear against the exchanger 7, and thus to stiffen these side walls, spacers 73, formed of sheets folded crenellated, are placed against the plates 71 which form the sides of the exchanger 7. The presence of these spacers 73 makes it possible to fill the space existing between the edges of the exchanger 7 and the side walls of the casing 1 10, without hindering the flow of fluids on the outside face of the plates 71 which form the sides of the exchanger 7.

It should be noted that, to facilitate the assembly of the assembly formed by the exchanger 7, the distribution box 74 and the cover 1 20 in the housing 1 1 0, the distance between the top of the ribs 1 1 3 and the bottom of the channel grooves 1 1 1 may be slightly greater than the height of the exchanger 7, to provide a set of mounting. However, under the normal conditions of use of the desorber, the very low pressure inside this desorber causes a small deformation of the walls of the casing 1 10 until these walls come into contact with the exchanger 7. contact then makes it possible to stiffen the walls.

In the desorber 100 according to the invention, the side walls, upper and / or lower housing 1 10 are supported on the exchanger 7, the support points being essentially evenly distributed on the faces concerned of the exchanger. This support makes it possible to reinforce the rigidity of this casing to avoid its deformation when it is at a pressure lower than the external pressure, without requiring too much reinforcement of the casing 1 1 0. Thus, this support makes it possible to manufacture a casing 1 1 0 which is of simpler design and uses less material, while maintaining a satisfactory rigidity.

According to another possible embodiment of the invention, the refrigerant and absorbent fluid mixture distribution system may be independent of the casing 1 1 0. In this case, this distribution may be made by a reported delivery member fixed inside the upper wall of the casing 1 10.

According to a possible embodiment, this distribution system may form a spacer allowing a support of the upper wall of the casing 1 10 on the top of the exchanger 7, to stiffen the upper wall. According to another possible embodiment, the distribution system can, by its own rigidity, reinforce the rigidity of the upper wall.

FIG. 8 represents an exchange plate 81 according to another possible embodiment of the invention. This plate 81 comprises a plurality of pipes 81 0 extending horizontally and intended to be traversed by the hot liquid providing heat to the desorber. It also comprises an upper pipe 81 1, similar to the pipes 810 but placed above them, which is pierced with lateral holes 812 distributed along its length. This pipe 81 1 is intended to be fed by the mixture of coolant and absorbent fluids to be evaporated, and the holes 812 allow the distribution of this mixture along the edges of the plate 81.

According to this embodiment, an independent mixing distribution system is not necessary in the desorber. In addition, the plate 81 shown in Figure 8 also has a spacer 813 at its upper end and a spacer 814 at its lower end. These two spacers allow the exchanger to be formed by such plates 81 to bear against the upper and lower walls of the casing 1 10 of the desorber 100 and thus to reinforce the rigidity of these walls against deformation due to the difference pressure between the inside and the outside of the desorber.

In this embodiment, the distribution boxes located at the ends of the exchanger are adapted to allow mixing of the feed pipes 81 1. It is also possible to distribute in each of the plates 81 a plurality of feed lines 81 1, at different heights of the plate 81, to optimize the distribution of the mixture on the plates 81.

Claims

1. Desorber (1 00) for an air-conditioning device by absorption, in particular for a motor vehicle, comprising a housing (1 1 0) in which are housed one or more constituents of the desorber, among which a heat exchanger (7), a mixture of absorbent fluid and refrigerant fluid being introduced into the housing (1 10), in contact with the heat exchanger (7), characterized in that the distribution system of the mixture of absorbent and refrigerant fluids is integrated into the upper wall of the box

(1 10).

2. Desorber according to claim 1, characterized in that said dispensing system is supported on the heat exchanger (7) housed in the housing (1 10).

3. Desorber according to claim 1 or claim 2, characterized in that the distribution system is constituted by a plurality of channel grooves (1 1 1) defined in said upper wall, the bottom of these channels (1 1 1). having holes (1 12) to allow flow in the housing of the fluids present in the channels

(1 1 1).

4. Desorber according to claim 3, characterized in that the channels (1 1 1) are shaped to form a corrugated structure reinforcing the rigidity of the housing.

5. Desorber according to claim 3 or claim 4, characterized in that the heat exchanger (7) comprises vertically extending exchange plates (71), and said channel grooves (1 1 1) are oriented parallel to the upper edges of these exchange plates (71).

Desorber according to any one of claims 3 to 5, characterized in that said channel grooves (11) are oriented in the direction of flow of the vapor produced in the desorber (100), in order to facilitate this flow.

7. Desorber according to any one of the preceding claims, characterized in that a cover (1 30) is placed above the upper wall of the housing (1 1 0), to form a fluid reservoir between the lid (1 30) and the top wall.

8. Desorber according to any one of the preceding claims, characterized in that the housing (1 10) has at least one of these other walls in direct or indirect support against the heat exchanger (7).

9. Desorber according to any one of the preceding claims, characterized in that the housing (1 10) has at least one of these other walls in direct or indirect support against the heat exchanger (7).

10. Desorber according to claim 9, characterized in that a spacer (73) is placed between at least one side face of the heat exchanger (7) and the corresponding wall of the housing (1 10).

1 1. Desorber according to claim 10, characterized in that said spacer (73) is formed by a bent plate of the same material as the heat exchanger (7).

12. Desorber according to any one of claims 8 to 1 1, characterized in that the bottom wall of the housing has a plurality of ribs (1 13) in contact with the heat exchanger (7).

13. Desorber according to claim 12, characterized in that the ribs (1 13) are oriented in the direction of flow of the fluid after its passage in contact with the exchanger (7).

14. Absorption air conditioning device, especially for a motor vehicle, characterized in that it comprises a desorber (100) according to any one of claims 1 to 13.

15. Motor vehicle, characterized in that it comprises an absorption air conditioning device according to claim 14.