FR2770289A1 - Condensate-shedding, heat-dissipating spacers for air-conditioner evaporator - Google Patents

Abstract

The evaporator has heat dissipating spacers of wire mesh, with concertina or crenelated profiles formed by repeated folding, with crests of these profiles inducing flow of condensate toward the bottom. Flat-sided flow-tubes (1) are fabricated by brazing together two shallow, dished pressings (2,3) whose concavities, facing each other, are separated by a partition plate (11), imposing a refrigerant flow-path down one side, and up the other. Adjacent tubes are interconnected at the top, through corresponding apertures left in deepened zones in the pressings. Below these zones, air flows horizontally, giving up heat to the flat tube sides. Heat transfer is enhanced by heat-dissipating spacers (21) inserted (8) between tubes, in contact with the sides. These are of wire mesh, with concertina or crenelated profiles formed by repeated folding on vertical lines (22).

Description

Spacer for evaporator promoting condensate flow
The invention relates to a heat exchanger for the transfer of heat from a first fluid in the gaseous state to a second fluid, in particular an evaporator for an air conditioning device for the passenger compartment of a vehicle, comprising a stack of pockets. mutually aligned in a first substantially horizontal direction in which the second fluid circulates, two consecutive pockets of the stack being separated, over at least a fraction of their surface, by an interval provided for the passage of the first fluid in a second substantially horizontal direction perpendicular to the first, interval in which an interlayer is arranged in the form of at least one corrugated sheet, the corrugation ridges of which come into contact with said two pockets so as to ensure good thermal contact between them and the second fluid circulating in the meantime.

Such heat exchangers are used in particular as evaporators in air conditioning devices, to cool an air flow to be sent into the passenger compartment of a vehicle by heat exchange with a refrigerant which changes from the liquid state to the gaseous state.

The cooling of the air can lead to the condensation of the humidity contained in it, on the cold parts that are the walls of the pockets and the spacers.

In known evaporators, the corrugation ridges of the spacers extend substantially horizontally so as to define horizontal channels for the circulation of air in the intervals. The contact zones between the inserts and the pockets, to which they are generally brazed, constitute zones for the retention and accumulation of condensates. The drops of water thus collected can be entrained by the air current and projected into the passenger compartment.

The object of the invention is to remedy these drawbacks by promoting the removal of condensate from the air flow passing through the evaporator.

The invention relates in particular to a heat exchanger of the kind defined in the introduction, and provides that said corrugation ridges extend substantially in a vertical direction and that the interlayer has through openings allowing the passage of the first fluid.

Thanks to the vertical orientation of the corrugation ridges, the condensates immediately flow from top to bottom over the entire surface of the pockets and the spacers, including along the contact zones between these parts, without encountering retention zones .

Optional, complementary or alternative characteristics of the invention are set out below: - The interlayer has a crenellated profile.

- The interlayer has a sawtooth profile.

- The interlayer is a grid formed of intertwined threads.

- The son extend one substantially horizontally, the other substantially vertically.

- At least some of the wires extend obliquely.

- The interlayer is a perforated plate.

- The interlayer is in the form of expanded metal.

The characteristics and advantages of the invention will be explained in more detail in the description below, with reference to the accompanying drawings, in which: - Figure 1 is a partial side view of a known evaporator - Figures 2 and 3 are partial perspective views of two embodiments of an evaporator according to the invention - Figures 4 to 7 show in perspective different forms of spacers usable in an evaporator according to the invention.

The known evaporator illustrated in FIG. 1, intended for a device for air conditioning the passenger compartment of a motor vehicle, comprises a multiplicity of pockets 1 mutually stacked from left to right, each formed from two sheets of sheet metal stamped in bowl-shaped 2 and 3.

The latter are identical to each other and have their concavities facing one another, that is to the right and to the left respectively. Each bowl has a peripheral edge 4 situated in a vertical plane, and the peripheral edges 4 of the two bowls forming a pocket are mutually assembled in a fluid-tight manner, for example by soldering, to delimit the interior volume of the pocket. We see at the top of the figure, for each of the bowls, a region 5 of greater depth than that of region 6, the latter occupying most of the height of the bowl, below the region 5. Two regions of greater depth of each bowl are thus juxtaposed from the front to the rear of FIG. 2, defining in each pocket an inlet chamber and an outlet chamber for the refrigerant.

The inlet chamber and the outlet chamber of each pouch are separated from each other by a sealed junction zone not shown between the two cuvettes at half the width of the pouch, this junction zone extending towards the down to the vicinity of the lower end of the bag so as to define therein a U-shaped path for the fluid between the inlet chamber and the outlet chamber. The bottom 7 of each bowl is crossed, in each of the regions 5 of greater depth, by an opening and the bottoms facing one another of a bowl 2 and a bowl 3 adjacent are mutually linked so waterproof around the openings, for example by soldering. The openings thus interconnect on the one hand all of the inlet chambers, on the other hand all of the outlet chambers, to respectively form an inlet pipe and an outlet pipe between which the U-shaped paths in the different pockets are arranged in parallel. The bottoms facing one another of a neighboring bowl 2 and a neighboring bowl 3 are moreover spaced from one another in their regions 6 of shallower depth. The intervals 8 thus defined between the pockets are intended to be traversed horizontally, from front to back of the figure or vice versa, by a flow of air which will transfer heat to the refrigerant fluid circulating in the pockets.

An interlayer 9 in the form of a corrugated sheet is placed in each interval 8, its corrugation ridges 10 alternately coming into contact with the bottoms of the two bowls limiting this interval.

In this known evaporator, the ripple ridges extend horizontally from back to front of the figure, therefore perpendicular to the stacking direction of the sleeves, so that each interlayer defines in the interval 8 where it is housed a multiplicity of horizontal channels for the circulation of the air flow to be cooled. Cutouts not shown can be made in the spacers to create turbulence in the air flow, thereby improving heat exchange between it and the fluid flowing in the pockets.

The horizontally elongated contact areas between the inserts 9 and the bowls 2, 3 constitute areas for the retention and accumulation of condensates.

Figure 2 shows in perspective the lower part of the left end region of an evaporator according to the invention, similar in its general structure to that of Figure 1. It shows a pocket 1 composed of two bowls 2 and 3 , the left bowl 2a of another pocket located to the right of the previous one, and a left end pocket 1b composed of a right bowl 3b similar to that of the first pocket and a planar end plate 20 linked tightly around the periphery of the latter bowl.

There are also two corrugated inserts 21 arranged in the gaps 8 between the pockets. The median junction zone of the bowls 2 and 3, separating the two branches of the U-shaped path of the refrigerant, is indicated by the reference 11.

According to the invention, the corrugation ridges 22 of the inserts 21, which rest on the pockets and are brazed to them, are oriented vertically so as not to retain the condensates and on the contrary to facilitate their flow towards the low.

In the example illustrated, the spacers have a sawtooth wave profile. To allow the passage of air in the horizontal direction, the spacers have openings, these openings being delimited by crisscrossed wires forming a grid. The wires extend in two oblique directions and the openings have substantially the shape of diamonds. This multiplicity of openings also causes turbulence in the air flow, without it being necessary to provide other means for this purpose.

FIG. 3 differs from FIG. 2 only in the shape of the interlayer 23 replacing the interlayer 21, which is composed of two wavy sawtooth grids, which each occupy half the thickness of the interval 8.

The ripple ridges 24 of each of the two grids come into contact alternately with a pocket and with the ripple crests of the other grid.

Figures 4 to 7 show other forms of grids usable in the evaporator of Figure 2 or that of Figure 3. The grids of Figures 4 and 5, like those of Figures 2 and 3, are wavy sawtooth . In FIG. 4, the constituent wires of the grid are oriented horizontally and vertically. In FIG. 5, they are oriented obliquely, and less inclined with respect to a horizontal plane than in FIG. 2.

The grids of Figures 6 and 7 have a slot profile. In FIG. 6 as in FIG. 4, the constituent wires are oriented horizontally and vertically, and in FIG. 7 as in FIG. 2, they are oriented obliquely to delimit diamond-shaped openings.

The grid wires can have other orientations than those described and shown. One can in particular cross substantially horizontal or vertical wires and oblique wires. The spacers may have other forms than that of a grid with crossed wires, in particular those of a perforated plate and of an expanded metal.

Claims (8)

Claims 1. Heat exchanger for transferring heat from a first fluid in the gaseous state to a second fluid, in particular an evaporator for an air conditioning device for the passenger compartment of a vehicle, comprising a stack of pockets (1) mutually aligned in a first substantially horizontal direction in which the second fluid circulates, two consecutive pockets of the stack being separated, over at least a fraction of their surface, by an interval (8) provided for the passage of the first fluid according to a second substantially horizontal direction perpendicular to the first, interval in which is disposed an interlayer in the form of at least one corrugated sheet (21) whose corrugation ridges (22) come into contact with said two pockets so as to ensure good contact between them and the second fluid flowing in the valley, characterized in that said ripple ridges extend substantially in a vertical direction and that the interlayer has through openings allowing the passage of the first fluid. 2. Heat exchanger according to claim 1, characterized in that the interlayer has a crenellated profile. 3. Heat exchanger according to claim 1, characterized in that the interlayer has a sawtooth profile. 4. Heat exchanger according to one of the preceding claims, characterized in that the interlayer is a grid formed of intertwined wires. 5. Heat exchanger according to claim 4, characterized in that the son extend one substantially horizontally, the other substantially vertically. 6. Heat exchanger according to claim 4, characterized in that at least some of the wires extend obliquely. 7. Heat exchanger according to one of claims 1 to 3, characterized in that the interlayer is a perforated plate. 8. Heat exchanger according to one of claims 1 to 3, characterized in that the interlayer is in the form of expanded metal.