STORAGE EVAPORATOR WITH CORRUGATED PLATE DESIGN FACILITATING THE FREEZING OF THE PCM

Abstract

The evaporator (12) for a motor vehicle air conditioning device comprises at least one refrigerant tube (22, 22A) intended to allow the circulation of a refrigerant fluid and at least one storage member (10) comprising at least one housing (16, 20) comprising a material referred to as a thermal storage material (21) intended to store frigories and release them to a ventilation fluid intended to circulate towards an interior of the vehicle. The housing (16) has a substantially hemispherical shape.

Claims

1. An evaporator for a motor vehicle air conditioning device comprising: at least one refrigerant tube configured to allow circulation of a refrigerant fluid; and at least one storage member comprising at least one housing comprising a thermal storage material for storing and releasing frigories to a ventilation fluid configured to circulate towards an interior of the vehicle, wherein the housing has a substantially hemispherical shape.

2. The evaporator as claimed in claim 1, in which the ventilation fluid is air.

3. The evaporator as claimed in claim 1, wherein the thermal storage material comprises a phase change material.

4. The evaporator as claimed in claim 1, wherein at least one wall of the refrigerant tube forms a wall of the housing.

5. The evaporator as claimed in claim 1, in which the member has at least two housings, the at least two housings being connected to one another in fluid communication.

6. The evaporator as claimed in claim 5, in which the at least two housings are connected to one another by a connecting duct.

7. The evaporator as claimed in claim 6, wherein the ratio between the radius of a housing and a dimension of the connecting duct connecting this housing to the other housing is comprised between 0.5 and 1.

8. The evaporator as claimed in claim 5, wherein each housing has a substantially hemispherical shape.

9. The evaporator as claimed in claim 5, wherein a radius of one of the at least two housings is different from that of another of the at least two housings.

10. The evaporator as claimed in claim 1, wherein the storage member comprises a plurality of housings distributed at the nodes of a regular lattice.

11. An air-conditioning device for a motor vehicle, comprising an evaporator as claimed in claim 1.

Description

[0030] One embodiment of the invention will now be described by way of nonlimiting example with reference to the following figures:

[0031] FIG. 1 is a perspective view of a storage member of the invention;

[0032] FIG. 2 is a perspective view and sectioned view of a housing comprising the thermal storage material; and

[0033] FIG. 3 is a sectioned view of part of an evaporator bearing a storage member according to an alternative form of the embodiment of the invention;

[0034] FIG. 4 is a perspective view of an evaporator comprising several storage members according to the invention.

[0035] FIGS. 1 to 3, depict a storage member 10 of an evaporator 12 for a motor vehicle air conditioning device according to a first embodiment of the invention. The storage member 10 takes the form of a plate and comprises two orifices 14 allowing the member 10 to be connected to the other elements that make up the evaporator 12 using conventional means of assembly (not depicted).

[0036] As may notably be seen in FIGS. 1 and 2, the storage member 10 comprises a plurality of housings 16 of substantially hemispherical shape and connected to one another in fluidic communication by means of connecting ducts 18. A connecting duct 18 connects two adjacent housings 16 in fluidic communication. Along the axis (XX') running transversally to the storage member 10, the height of the connecting duct 18 is less than the radius of the housings 16. In this embodiment, the hemispherical housings 16 have the same radius, here 3.5 millimeters. According to an alternative form of the present embodiment, at least two hemispherical housings have radii which differ. Here, the ratio between the radius of a housing 16 and the dimension of the connecting duct 18 along the axis (XX′) is 0.5, but in alternative forms, this radius is comprised between 0.5 and 1. In addition, the plurality of housings 16 is distributed at the nodes of a regular lattice referred to as a primitive hexagonal lattice by analogy with Bravais lattices. In alternative forms, the housings 16 are distributed according to another type of one-dimensional, two-dimensional or even three-dimensional regular lattice.

[0037] The dimension and distribution of the housings 16 have been devised to take account of the constraints involved in forming the aluminum which is the material from which the storage member 10 is produced. Aluminum is a lightweight material, and therefore, because of the absence of fins in the housings 16, the weight of the evaporator 12 is relatively low.

[0038] In addition the shape of the housings 16 and the way in which they are distributed in the storage member 10 are intended to limit the pressure drop experienced by a ventilation fluid passing through the evaporator 12. Here, the pressure drop does not exceed 30% by comparison with a similar evaporator without a storage member 10, or even with an evaporator comprising storage members distributed approximately one every four tubes.

[0039] In this exemplary embodiment of the invention, each housing 16 of the storage member 10 is of substantially hemispherical shape. According to an alternative form illustrated in FIG. 3, housings 16 of substantially hemispherical shape are connected to other housings 20 which are of substantially semi-ellipsoidal shape.

[0040] The housings 16 or 20 are intended to store frigories. In order to do so, the housings 16, 20 and the connecting ducts 18 are filled with a material referred to as a thermal storage material which in this instance is a phase change material (or PCM) 21 of a type known per se.

[0041] The evaporator 12 also comprises a plurality of refrigerant tubes 22 through which a refrigerant fluid circulates. This fluid may notably be of the HFO-1234yf type or any other refrigerant fluid capable of being used in motor vehicle air conditioning devices.

[0042] The evaporator 12 further comprises a plurality of rows of fins 24. Each row of fins 24, sometimes referred to as a corrugated interlayer, is positioned, along the axis (XX′), next to at least one refrigerant tube 22. These fins extend between two refrigerant fluid tubes 22, 22A like the storage member 10.

[0043] FIG. 4 depicts an evaporator 12 comprising a plurality of storage members 10. The storage members 10 are uniformly arranged along the axis (XX′) between two refrigerant tubes 22.

[0044] When the air conditioning device is in operation, the ventilation fluid, in this case air from outside the vehicle passes through the rows of fins 24. If the vehicle engine is running, the refrigerant fluid circulates throughout the air conditioning device. The refrigerant fluid therefore arrives at the evaporator 12 cold and therefore gives up frigories to the air passing through the rows of fins 24. The cooled air then circulates to the vehicle interior, which it may thus air-condition. At the same time, the refrigerant fluid releases some of its frigories to the PCM which solidifies. Because of the shape of the housings 16, 20, solidification occurs quickly and homogeneously. In addition, since solidification is an exogenous process, the PCM thus constitutes a “frigories reservoir”.

[0045] The transfer of heat, notably between the refrigerant tube 22A and the housings 16, 20 is all the more effective when, as may be seen from FIG. 3, a wall 26 delimiting the refrigerant tube 22A is also a wall delimiting the housings 16, 20. Thus, there is just one partition separating the tube 22A and the housings 16, 20. In addition, because the wall 26 is common to the housing 16, 20 and to the refrigerant tube 22A, the PCM is in contact with the refrigerant tube 22A over the entire surface of the wall 26, this too making it possible significantly to improve the efficiency of the transfer of heat between the PCM and the refrigerant liquid inside the tube 22A.

[0046] When the vehicle engine is not running, because the vehicle has stopped for a brief time, and when a user of the vehicle operates the air conditioning device, the PCM in the housings 16, 20 liquefies. Because liquefaction is endothermic the PCM releases the frigories it accumulated during solidification to the refrigerant liquid in the refrigerant tubes 22, 22A. The refrigerant liquid cools and in turn releases frigories to the air circulating through the rows of fins 24. The air is cooled and then blown into the vehicle interior which it air-conditions.

[0047] Of course, numerous modifications could be made to the invention without departing from the scope thereof.

[0048] In particular, the shape or arrangement of the fins could be modified, the arrangement of the storage members 10 and of the refrigerant tubes 22 relative to one another within the evaporator 12 could be varied.

[0049] It might also be possible to use various regular patterns for the layout of the housings 16, 20 of the storage member 10.