Cast-moulded distributor

Abstract

The present invention relates to a fluid distributor for a heat exchanger, in particular a dry expansion evaporator, which can be implemented in one single piece by moulding and provided with structures configured to obtain improved thermal exchange performances.

Description

[0001] CAST-MOULDED DISTRIBUTOR

[0002] DESCRIPTION

[0003] Technical field of the invention

[0004] The present invention relates to the field of the aeraulic systems, in particular of the air conditioning systems.

[0005] The present invention, more specifically, relates to a fluid distributor which can be implemented in one single piece by moulding and having improved features in performance and construction terms, particularly suitable to be used in a dry expansion evaporator.

[0006] Background

[0007] Among the heat exchangers used in the air conditioning systems there are some types which, in particular for high refrigerating capacities, comprise a casing - or shell - inside thereof a tube bundle is housed. A service fluid flows inside the tube bundle in order to exchange heat with a process fluid at a different temperature.

[0008] In some heat exchangers, such as the evaporators, the service fluid typically is an evaporating refrigerating fluid which circulates inside the tube bundle and cools down the process fluid. The latter passes outside the tube bundle housed inside the shell, passing through the heat exchanger.

[0009] Generally, a supply tube supplies refrigerating fluid to the heat exchanger, by engaging it in a head unit - or collector - thereof. In order to channel the refrigerating fluid in the tube bundle, the exchanger is generally provided with a dedicated distributor device.

[0010] Structurally, the known distribution devices typically provide a plurality of supplied ducts which engage, each one, a respective tubular element of the tube bundle. Solutions of this type, however, have the drawback of being structurally complex due to the expensive and sophisticated mechanical processing of the structure for connecting the supplied ducts with the purpose of keeping the wished output conditions while conveying the fluid in each bundle tube.

[0011] Moreover, such solution often does not guarantee a uniform distribution of the flow of refrigerating fluid in the tube bundle, by reducing significantly the performances of the heat exchanger in which the above-mentioned types of distributors are assembled.

[0012] Moreover, in the dry expansion evaporators, the distribution of the liquid at the inlet plays a key role in the overall performances of the apparatus. With respect to the flooded evaporators, for example, in which the shell acts as “equalizer” after the distributor since the refrigerant can move between the regions of the shell and wet better the exchange tubes, in the dry expansion evaporators the refrigerant entering the exchange tube is forced to cross the tube to its end, except for a small recirculation.

[0013] This means that if the amount of refrigerating liquid coming from the distributor into the tubes is not well distributed between the different regions of the bundle the performances decrease drastically due to the excess or the lack of the liquid itself. The difficulty in reaching a good liquid distribution is mainly due to the fact that in most cases the flow reaching the evaporator is in the biphasic state then with mixed liquid and gases; this makes the flow chaotic and difficult to be controlled in terms of liquid distribution.

[0014] In order to improve the liquid distribution at the inlet of a dry expansion evaporator it is known to provide some technical / construction measures.

[0015] Some solutions, for example, provide to install mechanical components having suitable geometry and size at the inlet of the evaporator supply manifold to obtain a more chaotic flow upstream of the tube plate. This allows to increase statistically the probability of better distributing the liquid in the different tubes of the bundle since other negative effects, such as gravity and inertia, become less relevant. However, the drawback of this solution is that it becomes almost impossible to cover well, with one single fixed geometry / size, all working conditions and the consequent different flow schemes at the inlet of the evaporator.

[0016] In other cases, one tries to act through an increase in the pressure drops of the distributor, which has a positive effect for the two-phase applications since there is a strict relationship between flow rate and pressure drops and a correct sizing of the distributor element can help in spreading the liquid between the different regions of the bundle.

[0017] It is also known to use a distributor with power elements dedicated for each bundle tube having specific shape so as to allow to control the flows reaching the bundle. The common configurations for this solution consist in an assembly between two capillary tubes with a basic metal plate. The disadvantage of these solutions is that they are generally expensive and difficult to be adapted to different geometries of the tube bundle.

[0018] Summary of the invention

[0019] The technical problem placed and solved by the present invention is then to provide a fluid distributor for an exchanger, in particular for a dry expansion evaporator, allowing to obviate one or more of the drawbacks mentioned above with reference to the known art.

[0020] Such problem is solved by a distributor according to claim 1 .

[0021] Preferred features of the present invention are set forth in the depending claims.

[0022] The invention relates to a fluid distributor for a dry expansion evaporator. Such distributor includes a plate-shaped base element comprising a plurality of through openings, each one having a first internal wall. On one face of the base element a plurality of protrusions are arranged, each one comprising a second internal wall defining a respective cavity of the protrusion.

[0023] Each through opening is arranged below a corresponding protrusion in such a way that the first and the second internal wall are flush and define therebetween an injection chamber of the fluid.

[0024] At least a protrusion comprises a distal end opposite to the base element bearing an orifice so as to form a continuous passage of fluid supply which comprises, in sequence, the through opening (of the plate-shaped element), the cavity and the orifice (of the protrusion).

[0025] Each protrusion of said plurality is connected monolithically to the base element.

[0026] It will be appreciated that the invention makes available a distributor in which the elements which allow to inject the refrigerating fluid are implemented of one piece, preferably through a cast-moulding process, with the distributor itself.

[0027] Advantageously, from one single mould it is possible to obtain a distributor having features of extreme versatility since the manufacturing process itself makes it adaptable to a plurality of sizes of exchangers having different number of ranks of the refrigerating circuit, that is rows of tubes of the tube bundle.

[0028] In particular, the distal end of the protrusions bears the orifice based on the design conditions of the evaporator and the design of the tube plate, starting from one single base design of the distributor applicable to all different arrangements of the tube plates with the same diameter of the evaporator shell and number of refrigerating circuits.

[0029] For example, if an evaporator has fifteen rows of exchange tubes on the bundle and the maximum rows which can be installed in the same evaporator model are twenty, only fifteen rows of protrusions are pierced and bear the orifice at the distal end and the remaining five remain occluded. This versatility allows to reduce drastically the complexity of the productive cycle in order to implement distributors different therebetween and then to reduce significantly the production costs. Moreover, the proposed distributor makes possible to machine the orifices in a simple way and with a high and standardized quality which does not depend upon the operator, as instead it happens in case of the known distributors in which capillary tubes are subsequently welded to the base element depending upon the type of application and the type of tube plate with which the distributor has to couple.

[0030] According to an additional aspect, the present invention provides a distribution assembly comprising the above-said distributor, an inlet manifold and a tube plate. The distributor results to be arranged between, and sealed coupled with, the inlet manifold and the tube plate, and the orifice of one or more protrusions faces a corresponding opening of the tube plate configured to receive a bundle tube.

[0031] Advantageously, under conditions of coupled distribution assembly, the extension of the protrusions in direction perpendicular to the base element of the distributor is equal to the distance between said tube plate and the base element itself.

[0032] Such configuration has the advantage of further simplifying the construction of the distribution assembly since it is possible to do without spacer elements, present in the distributor of known type in order to guarantee the correct positioning of the distributor and to prevent it to advance towards the tube plate. In the invention such elements are integrated in the distributor itself which results to be configured to rest, through the protrusions devoid of orifice, directly on the tube plate.

[0033] Still more preferably, the overall dimension of the distal end bearing said orifice is smaller than the dimension of the corresponding opening of the tube plate facing such protrusion in combination with the fact that, according to a preferred embodiment, the distributor comprises support means connecting two or more adjacent protrusions and which are intended for contact with the tube plate itself.

[0034] Such solution implements a fluid communication between the volume inside the exchanger tube and the free volume which is present between the distributor and the tube plate. This feature is extremely advantageous since it allows to define a balancing chamber for the distribution of the fluid entering the tube bundle allowing phenomena of recirculation of said (refrigerant) fluid between different bundle regions and it improves the operation performances of the exchanger.

[0035] Other advantages, features and use modes of the present invention will result evident from the following detailed description of some embodiments, shown by way of example and not for limitative purposes.

[0036] Brief description of figures

[0037] The figures of the enclosed drawings will be referred to, wherein:

[0038] ■ Figure 1 shows an exploded view of a distributor assembly of a two-circuit evaporator comprising a fluid distributor according to a preferred embodiment of the present invention;

[0039] ■ Figure 2 shows a lateral section of the distributor assembly illustrated in Figure 1 , under a coupled condition of the components;

[0040] ■ Figure 3 shows a portion of an overall view of a distributor according to an embodiment of the present invention;

[0041] ■ Figure 4 is an enlarged detail of a lateral section of Figure 3 showing an embodiment of the connection between protrusions of the distributor;

[0042] ■ Figure 5 is a further enlarged detail of Figure 4 showing a preferred embodiment of a protrusion of the distributor of the present invention; Figure 6 shows an enlarged view of a detail of Figure 2 illustrating the coupling region of the components of the distributor assembly;

[0043] ■ Figure 7 shows a section of an overall view of the distributor assembly of Figure 1 and related to the fluid passage from the manifold to the tube bundle;

[0044] ■ Figure 8 shows a section of a top view of the distributor assembly coupled to a tube bundle having a configuration with reduced tube rows;

[0045] ■ Figure 9 is an enlarged detail of Figure 8 showing protrusions of the distributor according to embodiment variants of the present invention.

[0046] Detailed description of preferred embodiments

[0047] The present invention will be described hereinafter by referring to the above- mentioned Figures.

[0048] By firstly referring to Figure 1 and Figure 2, an exploded view of a preferred embodiment of a fluid distributor assembly is illustrated, in particular a refrigerant fluid, designated as a whole with reference 50 and comprising a distributor 100 according to the present invention.

[0049] The distributor 100 of the present invention is intended to be used in heat exchangers, preferably evaporators, in particular dry expansion evaporators.

[0050] In the illustrated embodiments, the distributor assembly 50 further comprises a tube plate 30 and a manifold 20 for entering the fluid in the distributor assembly 50. As it can be seen, the distributor 100 is interposed between, and sealed coupled with, said manifold 20 and said tube plate 30. Under conditions of assembled group, the manifold 20 and the tube plate 30 delimit a chamber in which the distributor 100 is arranged.

[0051] The manifold 20 is configured to receive the fluid, in particular a two-phase refrigerant fluid, which enters the heat exchanger and it is coupled to the tube plate 30 on a coupling surface - designated with reference A. Typically, the coupling surface A is at a peripheral region of the manifold 20 and of the tube plate 30, which result to be configured so as to be able to flange together the two components therebetween. This peripheral region can have quadrilateral conformation, but different coupling geometries are possible.

[0052] In the illustrated example, the manifold 20 comprises two inlets 21 for said fluid. In embodiment variants, said inlets can be present in different number, for example one or four inlets, depending upon the operating modes of the exchanger in which the distributor assembly 50 will be assembled.

[0053] Under assembled condition, the manifold 20 results to be internally a hollow element through which the fluid can pass towards the tube plate 30. To this purpose, the manifold 20 preferably comprises three fluid sealing areas: a first sealing area with said inlets 21 , a second area between the distributor 100 and the manifold itself 20 to delimit a fluid supply chamber 22, a third area at said peripheral area for coupling with the tube plate 30.

[0054] The tube plate 30 comprises a plurality of openings 31 configured to receive a tube bundle, illustrated as a whole with reference 40. The tube plate 30 is represented as a plate with a circular geometry, exemplifying the tube plates used in the considered technical field. However, the geometry of the shown tube plate 30 is not limiting for the purposes of the present invention.

[0055] The plurality of openings 31 of the tube plate 30 puts in fluid communication the inlets of the manifold 21 with the exchange tubes of the bundle 40.

[0056] That is, each opening 31 of the tube plate 30 is configured for coupling with an end of a respective tubular element inside which, during use, the refrigerant fluid flows.

[0057] The openings 31 , where the tubes of the bundle 40 are fixed, are preferably arranged in vertical rows, staggered and comprised in a specific range based upon the mechanical and thermal design of the exchanger.

[0058] The overall configuration of the distributor assembly 50 assembled with the tube bundle 40 is so that the latter results to be arranged inside the shell of the exchanger (not illustrated in figures).

[0059] The example shown in Figure 1 and 2 relates to a distributor assembly 50 for an evaporator having two refrigerating circuits. Therefore, the openings 31 of the plate 30 are grouped in two main outflow areas 30’ corresponding, each one, to an inlet of the manifold 21. Consequently, two distributors 100 for each outflow area 30’ are provided. The configuration of the manifold 20 mainly depends upon the sizes of the evaporator, in terms of diameter, and upon the number of refrigerating circuits.

[0060] However, it has to be understood that the manifold 20 can be coupled with a tube plate 30 having a distribution of openings 31 or a number of outflow areas 30’ different from the illustrated ones.

[0061] By further referring to Figures 3-5, a preferred embodiment of the distributor 100 according to the present invention will be now described.

[0062] The distributor 100 comprises a substantially plate-shaped base element 101 , bearing a plurality of through openings 102, in particular holes.

[0063] Each through opening 102 comprises a first internal wall 103 delimiting the passage opening for the fluid.

[0064] On one face 101 A of said base element 101 a plurality of protrusions 104 is also arranged. Each protrusion 104 is internally hollow 104a and it is limited by a respective internal wall 105 of the protrusion 104.

[0065] Each through opening 102 of the base element 101 is arranged below a corresponding protrusion 104 in such a way that the first 103 and the second 105 internal wall are flush, that is without discontinuity. Each protrusion 104 of said plurality results to be connected monolithically to said base element 101. The base element 101 and the plurality of protrusions 104 are made in one single piece preferably by cast moulding. The distributor 100 is preferably made of aluminium or alloys thereof.

[0066] The set of an opening 102 and a respective cavity 104a of the protrusion 104 define an injection chamber 107 of the fluid. Moreover, one or more of said protrusions 104 comprises a distal end 104b - opposite to the face 101 A of the base element 101 therefrom it protrudes - bearing an orifice 108 so as to form a fluid supply passage towards the tube bundle 40.

[0067] Said supply passage comprises in sequence, the through opening 102 in the base element 101 , the cavity 104a of the protrusion 104 and the orifice 108 in the distal end 104b. In fact, under conditions of assembled distribution assembly 50, the orifice 108 faces a corresponding opening 31 of the tube plate 30.

[0068] The fluid entering the manifold then enters the above-mentioned supply chamber 22 and subsequently flows in the injection chamber 107 of the distributor 100 by crossing the supply passage.

[0069] Preferably, the internal size of the cavity 104a reduces starting from said base element 101 towards said distal end 104b. Said internal size is meant as the distance between points on the internal wall 105 of the cavity 104a opposite with respect to the development direction of the protrusion 104.

[0070] The cavity 104a can have for example a rotational symmetry around a development axis P of the protrusion 104 projecting from the base element 101. In embodiments, the cavity 104a can assume a conical or truncated cone shape.

[0071] Still more preferably, the internal dimension of said injection chamber 107 reduces progressively starting from said through opening 102 towards said distal end 104b. The fluid injection chamber 107 is preferably a conical chamber converging towards the distal end 104b of the protrusion 104. Advantageously, such specific shape of the injection chamber 107 guarantees an improved mixing of the two-phase fluid before flowing in the thermal exchange tubes 40 of the tube plate 30 and it results in a positive effect on the exchanger performances.

[0072] According to a preferred embodiment of the distributor 100, the dimension of said orifice 108 is smaller than the dimension of the corresponding through opening 102 of the base element 101. Each orifice 108 is preferably a hole calibrated in diameter and can be implemented advantageously with a numerical control machine. Advantageously, the distributor 100 provides that two or more protrusions 104 bear orifices 108 of different dimension.

[0073] It is then possible to obtain different types of distributors with high constructive quality, but with a simple and cheap process, wherein each distributor implements, in principle, a different operating condition of the exchanger since, in the phase of manufacturing the distributor starting from the same mould, it is possible to customize the protrusions by implementing orifices having different widths.

[0074] It is specified that, for the purposes of the present invention, it is not required that all protrusions 104 of the distributor 100 bear an orifice 108. According to an advantageous aspect, which will be described more in detail hereinafter, some protrusions 104 can be devoid of orifice 108 and then they cannot allow the fluid communication between the injection chamber 107 and the exchange tubes 40 of the tube plate 30. Such constructive choice of depriving some protrusions 104 of their own orifice makes much more versatile and adaptable the distributor 100 to different types of exchangers which already have, for example, different number of ranks of the refrigerating fluid.

[0075] In a preferred embodiment, even the external dimension of the protrusion 104 reduces starting from the base element 101 towards the distal end 104b. The external dimension is meant as the overall dimension of the body of the protrusion 104, that is the distance between points on the external face of the protrusion 104 opposite with respect to the development direction of the protrusion itself.

[0076] According to the illustrated embodiments, each protrusion 104 projects perpendicularly from the base element 101 , that is according to a development axis P orthogonal to the plane comprising the base element 101 .

[0077] Moreover, the distributor 100 advantageously comprises support means connecting two or more adjacent protrusions 104 and which are intended for contact with the tube plate 30. Such feature is preferably implemented in combination with an aspect characterizing the distributor, that is the extension of the protrusions 104 with respect to a plane comprising said base element 101. Such extension is equal to the distance between said tube plate 30 and the base element 101 , in particular its face 101 A therefrom said protrusions 104 project.

[0078] By further referring to Figures 6-7, the distributor 100 - under condition assembled in the distributor assembly 50 - faces said orifice 108 at an outflow section E further comprising a corresponding opening 31 of the tube plate 30 by creating a fluid communication between the supply chamber 22, the injection chamber 107 and the thermal exchange tube 40.

[0079] Said support means acts as elements spacing apart from the tube plate 30 and they guarantee the correct positioning of the distributor 100 with respect to the tube plate 30 through the contact with the latter, by also preventing an additional advancement of the distributor 100 towards the plate 30.

[0080] In an embodiment, said support means is in form of kerbs 109 connecting the distal ends 104b of adjacent protrusions 104. Such kerbs 109 implement a connection which makes available a resting surface of the distributor according to a direction so as to allow a contact with the present space between corresponding adjacent openings 31 (of staggered rows of thermal exchange tubes 40) born by the tube plate 30.

[0081] According to embodiment variants, such support means 109 can further include one or more distal ends 104b of protrusions 104 devoid of orifices 108. By further referring to Figures 8 and 9, for example, the number of openings 31 of the tube plate 30 facing a corresponding distal end 104b of a protrusion 104 having an orifice 108 is lower than the total number of protrusions 104 of the distributor 100. In this case, the excess of protrusions 104 is devoid of an orifice 108 at its own distal end 104b.

[0082] It will be appreciated that the distributor 100 of the present invention is structured in order to be a self-supporting element in which the protrusions 104, thanks to its own extension in height from the base element 101 , guarantee a safe coupling between the distributor 100 itself and the manifold 20.

[0083] Preferably, such coupling is perfected by the presence of fluidic sealing means, represented in an exemplifying way by two gaskets designated with the same reference 10 in Figure 1 , in order to guarantee the sealing between the above- mentioned supply chamber 22 and a balancing chamber B which remains defined between the distributor 100 and the tube plate 30.

[0084] Advantageously, the support means 109 is further configured to push the distributor 100 towards said sealing means 10 which result to be arranged between the distributor 100 and the manifold 20.

[0085] As it is clearly visible in Figure 7, in a particularly advantageous embodiment of the invention, the overall dimension of the distal end 104b of the protrusion 104 is smaller than the dimension of the corresponding opening 31 of the tube plate 30 facing such protrusion.

[0086] In other words, the outflow section E is not wholly occupied by the distal end 104b of the protrusion 104 which, additionally, is not inserted in the tube plate 30, under conditions of assembled distribution assembly 50.

[0087] The net outflow section is an annular surface surrounding the external dimension of the distal end 104b of the protrusion 104. In the example such annular surface is represented by a circular crown.

[0088] Based upon the pressure delta present between the inlet and the outlet of the bundle tube 40, the fluid advancing from the injection chamber 107 through the supply passage towards the exchange tube 40 associated thereto - as shown by the arrow F - can flow back through such outflow section E, it can enter the balancing chamber B and it can reach outflow sections E associated to different exchange tubes 40 placed nearby - as shown by the arrows F’. The fluid fillingin the balancing chamber B migrates, that is, towards the less supplied bundle tubes 40 in order to guarantee the equilibrium of the pressure delta through the tube bundle 40.

[0089] It will be appreciated that the balancing chamber B advantageously allows the fluid recirculation between the different bundle tubes 40 and contributes to uniform the flow rates. That it, there is a space, comprised between the surface 101 A of the distributor 100 facing the tube plate 30 and the surface A of the tube plate 30 itself bearing the openings 31 configured to receive (or bearing) the exchange tubes 40, which puts in fluid communication the latter and allows to balance possible imbalances in the distribution.

[0090] The present invention has been sofar described with reference to preferred embodiments. It is to be meant that other embodiments belonging to the same inventive core may exist, as defined by the protective scope of the herebelow reported claims.

Claims

CLAIMS1. A fluid distributor (100) for a heat exchanger, in particular a dry expansion evaporator, which distributor comprises:■ a plate-shaped base element (101 ) comprising a plurality of through openings (102) each one having a first internal wall (103),■ a plurality of protrusions (104) arranged on a face (101 A) of said base element (101 ), each protrusion (104) comprising a second internal wall (105) defining a protrusion’s cavity (104a), wherein each through opening (102) is arranged below a corresponding protrusion (104) in such a way that said first (103) and second (105) internal wall are flush and define therebetween an injection chamber (107), wherein at least a protrusion (104) comprises a distal end (104b) opposite said base element (101 ) and bearing an orifice (108) so as to form a fluid supply passage, said passage sequentially comprising said through opening (102), said cavity (104a) and said orifice (108), wherein each protrusion (104) of said plurality is connected monolithically to said base element (101 ).

2. The distributor (100) according to claim 1 , wherein said base element (101 ) and the plurality of protrusions (104) are made in one single piece by cast moulding.

3. The distributor (100) according to claim 1 or 2, wherein the internal dimension of said cavity (104a) reduces from said base element (101 ) to said distal end (104b).

4. The distributor (100) according to claim 3, wherein the internal dimension of said injection chamber (107) reduces from said through opening (102) to said distal end (104b).

5. The distributor (100) according to claim 3 or 4, wherein the dimension of said orifice (108) is smaller than the dimension of the corresponding through opening (102).

6. The distributor (100) according to one or more of the preceding claims, wherein the external dimension of the protrusion (104) reduces from the base element (101) to the distal end (104b).

7. The distributor (100) according to one or more of the preceding claims, wherein two or more protrusions (104) of said plurality comprise orifices (108) of different dimension.

8. The distributor (100) according to one or more of the preceding claims further comprising support means (109) connecting two or more adjacent protrusions (104) and intended for contact with a tube plate (30) of the heat exchanger.

9. The distributor (100) according to one or more of the preceding claims, wherein said plurality of protrusions (104) protrude perpendicularly from said base element (101).

10. A fluid distribution assembly (50) comprising■ an inlet manifold (20),■ a tube plate (30) comprising a plurality of openings (31 ) configured to receive a tube bundle (40),■ a distributor (100) according to one or more of the preceding claims, arranged between, and sealed coupled with, said inlet manifold (20) and said tube plate (30), wherein the distal end (104b) of one or more protrusions (104) has an orifice (108) facing a corresponding opening (31 ) of said tube plate (30).

11. Distribution assembly (50) according to the previous claim, wherein the extension of the protrusions (104) with respect to a plane comprising said baseelement (101 ) is equal to the distance between said tube plate (30) and said base element (101 ).

12. The distribution assembly (50) according to claim 10 or 11 , wherein the overall dimension of the distal end (104b) of at least a protrusion (104) is smaller than the dimension of the corresponding opening (31 ) of the tube plate (30) facing said at least a protrusion.

13. The distribution assembly (50) according to any one of claims 10 to 12, wherein the number of openings (31 ) of said tube plate (30) facing a corresponding distal end (104b) of a protrusion (104) having an orifice (108) is equal to or less than the total number of protrusions (104) of the distributor (100), wherein the excess of protrusions (104) is devoid of an orifice (108) at its distal end (104b).

14. The distribution assembly (50) according to any one of claims 10 to 13 comprising a distributor (100) according to claim 8 or 9, wherein said support means (109) is configured to push the distributor (100) towards sealing means (10) arranged between said distributor (100) and said manifold (20).

15. A dry expansion evaporator comprising:■ a shell,■ a distribution assembly (50) according to one of claims 10 to 14,■ a tube bundle (40) arranged inside the shell, wherein an end of each tube of said tube bundle (40) is coupled with an opening (31 ) of the tube plate

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