Duct or vessel comprising a separating element

Abstract

A duct or vessel comprising a separating element (30) which includes a pair of plates (31, 32), each of which comprises a central portion (31a, 32a) and a peripheral edge (31b, 32b) raised with respect to the central portion (31a, 32a), the plates (31, 32) being joined to each other at their respective central portions (31a, 32a) so as to define an annular gap (G) around the central portions (31a, 32a), interposed between the peripheral edges (31b, 32b) of the plates (31, 32). Each of the plates (31, 32) has a profile in radial cross-section comprising an inflection point (P1, P2) between the central portion (31a, 32a) and the peripheral edge (31b, 32b), wherein the tangent to the plate (31, 32) at the inflection point (P1, P2) defines an opening angle α with respect to an interface plane (M) between the plates (31, 32). The opening angle α satisfies the relation: θ+α≥90°, where θ is the wetting angle between the molten braze-welding filler material and the base material of the separating element (30).

Description

[0001] The present invention relates to a duct or vessel comprising a separating element that divides the interior of the duct or vessel into a first inner space and a second inner space, and is joined to said duct or vessel by braze-welding, wherein the separating element comprises a pair of plates, each of which comprises a central portion and a peripheral edge raised with respect to the central portion, said plates being joined to each other at their respective central portions so as to define an annular gap around said central portions, said annular gap being interposed between the peripheral edges of the plates, fluidically communicates with a through-hole formed on a side wall of the duct or vessel, wherein each of said plates has a profile in radial cross-section comprising an inflection point between the central portion and the peripheral edge, wherein the tangent to said plate at said inflection point defines an opening angle α with respect to an interface plane between the plates.

[0002] Ducts of this type are, for example, the distributors of heat exchangers used in HVAC systems with heat pumps.

[0003] In such heat exchangers, a separating baffle is installed to divide the passages inside the heat exchanger. When there is an internal leak from the separator (i.e., leakage between the two internal spaces created within the partitioned distributor), this results in a significant loss of performance. Detecting such leaks during the manufacturing process is highly complex, and the available detection systems often lack the sensitivity required to detect small leaks that could still negatively impact the performance of the heat exchanger. JP 2016099097 A describes a heat exchanger provided with manifolds formed by a plate and a tank assembled together and comprising a separator formed by a pair of plates provided with a protruding structure through a wall of the tank. The plates are joined to each other at their respective central portions in such a way as to define an annular gap around said central portions, interposed between the peripheral edges of the plates. The aforementioned separator improves detection by ensuring that any leakage is directed towards the exterior of the heat exchanger, making it detectable through a simple pressure-tightness test.

[0004] It has been observed that the braze-welding process can cause the annular gap to become filled with the molten filler material, thereby nullifying the above-described function of the separating element.

[0005] An object of the invention is to provide a solution capable of at least partially overcoming the aforementioned drawback.

[0006] This object is achieved, according to the invention, by a duct or vessel of the type defined above, wherein said opening angle α satisfies the relation: θ + α ≥ 90 ° , where θ is the wetting angle between the molten braze-welding filler material and the base material of the separating element.

[0007] In this way, a geometry is created that prevents the annular gap between the plates from being filled with the molten filler material during the braze-welding process. The corner fillet between the plates has a capillary pressure corresponding to its shape. Increasing the angle α results in an increase in the capillary pressure of the fillet. Specifically, if θ+α ≥ 90°, the shape of the fillet changes from concave to convex. At this point, the capillary pressure of the fillet transitions from negative to positive, causing the molten filler material to flow into areas with lower capillary pressure, thereby preventing the filling of the space between the two plates.

[0008] Although the invention has been conceived within the context of separators used in the heat exchangers distributors, it is evident to a skilled person in the field that it may find application in other areas where it is necessary to prevent clogging of the annular gap defined by the separator.

[0009] Preferred embodiments of the invention are defined in the dependent claims, which are to be considered an integral part of the present description.

[0010] Further features and advantages of the invention will become clearer from the following detailed description of an embodiment of the invention, made with reference to the accompanying drawings, provided purely for illustrative and non-limiting purposes, wherein: Figure 1 is a perspective view of a heat exchanger; Figure 2 is a perspective view of a detail of a duct or vessel according to the invention; Figure 3 is a sectional perspective view of the detail of Figure 2; Figure 4 is a sectional view of the detail of Figure 2; Figure 5 is a geometric diagram representing a separating element of the duct or vessel of Figure 2; Figure 6 is a graph representing the capillary pressure as a function of the fillet volume for different values of the opening angle α; Figures 7 and 8 are photographs of a detail of the separating element, respectively with an opening angle α of 45° and 75°.

[0011] With reference to Figure 1, a heat exchanger made of metallic material, particularly aluminium, is generally indicated by 1. In the illustrated example, the heat exchanger 1 is a fluid-air heat exchanger, specifically an internal condenser of an HVAC system with a heat pump for an electric vehicle. However, this example is not to be considered binding, as the invention may find application in other fields where a separator is positioned in a duct or vessel.

[0012] The heat exchanger 1 comprises at least a first distributor 11 and at least a second distributor 12, and a plurality of parallel, coplanar tubes 13 interconnecting the first distributor 11 and the second distributor 12. Between adjacent tubes 13, fins 14 are interposed, though not shown in detail. On opposite sides of the assembly formed by the tubes 13, two side plates 15 and 16 are attached.

[0013] The above-described elements are joined together in a known manner, for example, by braze-welding.

[0014] Each of the distributors 11, 12 has a tubular body, for example, with a circular cross-section, on a side wall 11a, 12a of which a plurality of slits 17 are formed, each of which houses an end of a respective tube 13.

[0015] As shown in Figures 1 to 4, inside at least one of the distributors 11, 12, a separating element 30 is arranged, which divides the interior of the partitioned distributor 11 into a first inner space 11' and a second inner space 11". The separating element 30 is inserted into a linear through-hole 18, formed on the side wall 11a of the partitioned distributor 11 and parallel to the slits 17 for the tubes 13. The separating element 30 has an edge abutting against an internal surface of the partitioned distributor 11, and opposite faces contiguous to respective edges 18' of the through-hole 18. The separating element 30 is joined to the partitioned distributor 11 by material bonding, specifically by braze-welding.

[0016] The separating element 30 comprises a pair of plates 31, 32, each of which includes a central portion 31a, 32a and a peripheral edge 31b, 32b raised with respect to the central portion 31a, 32a. As can be appreciated in Figures 3-4, the plates 31, 32 are joined to each other at their respective central portions 31a, 32a in such a way as to define an annular gap G around the central portions 31a, 32a. The annular gap G is interposed between the peripheral edges 31b, 32b of the plates 31, 32, and therefore communicates with the external environment through the part of the through-hole 18 located between the peripheral edges 31b, 32b of the plates 31, 32. Any fluid leakage between the edges of the separating element 30 and the internal surface of the partitioned distributor 11 is thus detectable through the through-hole 18 via a leak test.

[0017] With reference also to Figure 5, each of the plates 31, 32 has a profile in radial cross-section comprising an inflection point P1, P2 between the central portion 31a, 32a and the peripheral edge 31b, 32b (the arrangement of the plates 31, 32 is symmetrical with respect to the interface plane defined between the plates 31, 32). The tangent to the plate 31, 32 at the inflection point P1, P2 defines an opening angle α with respect to an interface plane M between the plates 31, 32 (for simplicity, in Figure 5, only the opening angle associated with plate 32 is shown, assuming that the opening angle associated with the other plate 31 is substantially the same).

[0018] The opening angle α satisfies the relation: θ + α ≥ 90 ° , where θ is the wetting angle between the molten braze-welding filler material and the base material of the separating element 30.

[0019] In this way, a geometry is created that prevents the annular gap G between the plates 31, 32 from being filled with the molten filler material during the braze-welding process. The corner fillet between the plates 31, 32 has a capillary pressure corresponding to its shape. Increasing the angle α causes an increase in the capillary pressure of the fillet, as represented in the graph of Figure 6. Specifically, if θ + α ≥ 90°, the shape of the fillet changes from concave to convex. At this point, the capillary pressure of the fillet transitions from negative to positive, causing the molten filler material to flow into areas with lower capillary pressure, thereby preventing the filling of the space between the two plates. Figures 7 and 8 are photographs of a detail of the separating element 30 between the plates 31, 32 and the wall 11a of the distributor 11, respectively with an opening angle α of 45° and 75°. As can be observed, in the case where α = 45°, the annular gap between the plates 31, 32 is clogged by the filler material, whereas in the case where α = 75°, the annular gap is substantially free from the filler material.

Claims

1. Duct or vessel comprising a separating element (30) which divides the interior of the duct or vessel (11) into a first inner space (11') and a second inner space (11"), and is joined to said duct or vessel (11) by braze-welding, wherein the separating element (30) comprises a pair of plates (31, 32), each of which comprises a central portion (31a, 32a) and a peripheral edge (31b, 32b) raised with respect to the central portion (31a, 32a), said plates (31, 32) being joined to each other at their respective central portions (31a, 32a) so as to define an annular gap (G) around said central portions (31a, 32a), interposed between the peripheral edges (31b, 32b) of said plates (31, 32), said annular gap (G) fluidically communicating with a through-hole (18) formed on a side wall (11a) of said duct or vessel (11), wherein each of said plates (31, 32) has a profile in radial cross-section comprising an inflection point (P1, P2) between the central portion (31a, 32a) and the peripheral edge (31b, 32b), wherein the tangent to said plate (31, 32) at said inflection point (P1, P2) defines an opening angle α with respect to an interface plane (M) between the plates (31, 32), characterized in that said opening angle α satisfies the relation: θ + α ≥ 90 ° , where θ is the wetting angle between the molten braze-welding filler material and the base material of the separating element (30).

2. Heat exchanger comprising a first distributor (11) and a second distributor (12) and a plurality of parallel, coplanar tubes (13) interconnecting the first distributor (11) and the second distributor (12), wherein each of said distributors (11, 12) has a tubular body, on a side wall (11a, 12a) of which a plurality of slits (17) are formed, in each of which an end of a respective tube (13) is inserted, wherein at least one of said distributors is a duct or vessel according to Claim 1.

Images