WO2023095025A1 - Improved hybrid evaporator assembly - Google Patents

Abstract

Evaporator assembly (1) for evaporating a refrigerant fluid of a refrigerant arrangement, said evaporator assembly (1) comprising a housing (2) defining a space (3) extending along a longitudinal axis (A), the evaporator assembly (1) comprising a hybrid evaporation module (10) housed within said space (3) and comprising a tube bundle (12) provided with a plurality of tubes (12a) configured to allow the passage of an operative fluid, a support structure (13) and a distributor (11), the distributor (11)comprises a conduit assembly (22)that is positioned in a middle position along the longitudinal axis (A) and the distribution conduits (21) extends above the tube bundle (12), the distribution conduits (21) being disposed in a symmetric manner with respect to the transversal axis (C) and the vertical axis (D).

Description

"IMPROVED HYBRID EVAPORATOR ASSEMBLY"

Cross-Reference to Related Applications

This Patent Application claims priority from Italian Patent Application No. 102021000029945 filed on November 26, 2021 the entire disclosure of which is incorporated herein by reference.

Technical Field

The present invention concerns an evaporator assembly, in particular a hybrid evaporator assembly.

The present invention finds its preferred, although not exclusive, application in a fluid conditioning circuit such as a conditioning circuit for refrigerating arrangements.

Background of the Invention

Evaporators are used for allowing the passage of a fluid from a liquid phase to a gaseous phases. In conditioning circuits evaporators are used for allowing a refrigerant fluid to pass from liquid phase to gaseous phases by subtracting heat from another operative fluid passing in the evaporator .

In particular, in almost all arrangement, the evaporator comprises a housing defining a space into which the refrigerant fluid is inserted and forced to pass through a tube bundle that is configured to allow the passage of operative fluid in the aforementioned space for exchanging heat with the refrigerant fluid.

Furthermore, the aforementioned evaporator arrangement may be designed in some known configuration, among which:

• the flooded evaporators, wherein at least part of the tube bundle is sunk in liquid phase of the refrigerant fluid,

• the falling film evaporators, wherein the refrigerant fluid is poured on the tube bundle, or

• the spraying evaporators, wherein the refrigerant fluid is sprayed on the tube bundle. Another known typology of evaporators is the so-called hybrid evaporator i.e. a combination of flooded evaporators and falling f ilm/spraying evaporators.

Hybrid evaporators are advantageous to increase performances of the evaporator assembly, in general.

However, hybrid evaporators still have a considerable load, i.e. they use a flow of refrigerant fluid that may be further optimized. Moreover, the distribution of the refrigerant fluid highly dependents on the typology of refrigerant fluid.

Accordingly, specific solutions for allowing a uniform distribution of the refrigerant fluid should be proposed, thereby increasing production costs. Conversely, a universal design solution would lead to a not-uniform distribution of the refrigerant fluid.

The not-uniform distribution of refrigerant fluid lead to a decreasing thermal exchange efficiency and increases the possibility that liquid phase evaporator fluid drops may be sucked downstream to the evaporator.

The need of a uniform distribution of refrigerant fluid is furthermore felt because both the outlet sucking conduit of the evaporator and the inlet refrigerant conduit are usually placed inclined with respect to a vertical axis of the evaporator and inclined one with respect to the other.

Such arrangement, needed because of installation requirements space, needs a good refrigerant fluid distribution to avoid drops of liquid phase refrigerant to be sucked by the outlet conduit.

Therefore, the need is felt to improve existing hybrid evaporator assemblies in order to increase their efficiency, in particular by reducing their load ad increasing the distribution of refrigerant fluid within the tube bundle.

An aim of the present invention is to satisfy the above mentioned needs in a cost-effective and optimized manner. Summary of the Invention

The aforementioned aim is reached by a hybrid evaporator assembly as claimed in the appended set of claims.

Brief Description of Drawings

For a better understanding of the present invention, a preferred embodiment is described in the following, by way of a non-limiting example, with reference to the attached drawings wherein:

• Figure 1 is a perspective view of an evaporator assembly according to the intention;

• Figure 2 is a cross-sectional view along a transversal plane with respect to a longitudinal axis of the evaporator assembly of figure 1;

• Figure 3 is a perspective view of an internal portion of the evaporator assembly of figure 1 with parts removed for sake of clarity;

• Figure 4 is a further perspective view of an internal portion of the evaporator assembly of figure 1 with parts removed for sake of clarity; and

• Figure 5 is a perspective exploded view of an element of the evaporator assembly.

Detailed Description of the Invention

In the attached figures, reference number 1 globally indicates an evaporator assembly 1 according to the invention .

The evaporator assembly 1 comprises a housing 2 defining a closed space 3. The housing 2 comprises an intermediate portion 2a and a pair of terminal portion 2b configured to be secured to the intermediate portion 2a.

Preferably, the intermediate portion 2a has a tubular cylindrical shape extending along a longitudinal axis A; terminal portions 2b each comprises a perimeter part 2b' configured to allow the fixation of the assembly 1 to ground or to support structure of a refrigerant apparatus and a central part 2b' ' configured to mate with the intermediate portion 2a to close the space 3. In the disclosed embodiment, the perimeter pat 2b' has a quadrangular shape.

Accordingly, space 3 has a cylindrical shape along axis A that is radially delimited by intermediate portion 2a and axially delimited by central part 2b' ' .

The evaporator assembly 1 further defines a first opening 4 and a second opening 5 configured to be coupled to, respectively, an outlet conduit (not shown) and an inlet conduit (not shown) of a refrigeration assembly comprising evaporator assembly 1.

According to the shown embodiment, the first and second openings 4, 5 are defined on respective first and second manifolds 6, 7, i.e. respectively an outlet and an inlet manifolds 6, 7, extending from an outer surface of the intermediate portion 2a of the housing 2.

In particular, the first and second manifolds 6, 7 extends along respective axis B and C that are inclined with respect to a vertical axis D perpendicular to longitudinal axis A of the evaporator assembly 1.

In particular, the axis C of second manifold 7 is preferably perpendicular to vertical axis D and to longitudinal axis A while the axis B of first manifold 6 is inclined, i.e. presenting an acute or obtuse angle with respect to axis C or D.

The housing 2 may further define other elements or openings, such as a level viewer 8 not further described into detail.

In the exemplarily shown embodiment two evaporator assemblies 1 are arranged with a common terminal portion 2b along longitudinal axis A.

The evaporator assembly 1 comprises a hybrid evaporation module 10 housed within the space 3, the hybrid evaporation module 10 comprises a refrigerant distributor 11, a tube bundle 12 and a support structure 13 for supporting the tube bundle 12 and, preferably, also the refrigerant distributor 11.

The tube bundle 12 comprises a plurality of tubes 12a, having preferably the same equivalent diameter; in the disclosed embodiment they are circular and all of the same diameter .

The tubes 12a are configured to allow the circulation of an operative fluid between an inlet 14 and an outlet 15, preferably carried by one of terminal portion 2b.

In particular the outer tubes 12a of the tubes bundle 12, e.g. second, third and fourth tubes groups 12' ' , 12' ' ' , 12' ' ' ' , are fluidly connected to inlet 14 while the inner tubes 12a of the tube bundle 12, e.g. first tubes group 12' are fluidly connected to outlet 15. According to the above, the outer tubes 12a have a greater temperature with respect to the inner tubes 12a according to vertical axis D direction .

The inner and outer tubes 12a are fluidly connected together to allow the counter flow passage of the fluid contained therein in terminal portion 2b opposite to the one housing inlet 14 and outlet 15.

Conversely, in the terminal portion 2b housing the inlet 14 and outlet 15 divisor walls may be placed to guide the fluid flow in the correct outer and inner tubes without mixing. An exemplarily embodiment, not further described for sake of brevity, may be found in EP3748270 Al for sake of example .

In particular, the tubes 12a are disposed symmetrically with respect to longitudinal axis A and are vertically placed below the distributor 11.

Advantageously, the support structure 13 comprises a plurality of walls configured to define a space 16 that is vertically delimited on one side and opened towards the bottom of space 3 on the opposite and laterally delimited by the wall of support structure 13. The space 16 has therefore a parallelepiped shape, opened towards the bottom. The tubes 12a of tube bundle 12 are grouped in different tube groups. A first tubes group 12' is housed in an upper portion of space 16, i.e. closer to distributor 11, a second tubes group 12' ’ is housed below the first tubes group 12' and partially extends over space 16 in space 3, a third tubes group 12' ' ' extends in the bottom portion of space 3 and a pair of fourth tubes groups

' are placed laterally comprised between the support structure 13 and intermediate portion 2a of housing 2 in an upper portion of space 3, i.e. above the half line of the cross-section of the intermediate portion .

In particularly, as more clear in figure 2, the first tubes group 12' has a substantially rectangular distribution in space 3, the second tubes group 12' ' has a substantially rectangular distribution with a lower edge having variable height in space 3, the third tubes group 12' ' ' has a substantially semicircular distribution in space 3 and the fourth tubes group 12' ' ' ' has a substantially linear distribution in space 3, preferably, inclined with respect to vertical axis D.

Making reference to figure 3 for a better visual representation of structure 13 it can be appreciated that structure 13 comprises perimeter walls 20 configured to delimit the space 16. In particular, the perimeter walls 20 comprises a top wall and a pair of lateral walls.

The distributor 11 is configured to be at least partially housed within space 13 and configured to let refrigerant fluid to be dispensed over tube bundle 12.

In particular, the distributor 11 comprises a plurality of distribution tubes 21 fluidly connected to a conduit assembly 22. The conduit 21 is fluidly connected to manifold 7 to allow refrigerant fluid flows within evaporator assembly 1 and is advantageously positioned in correspondence of intermediate portion 2a along longitudinal axis A.

In particular, it is noticed that distribution tubes 21 are placed within space 16 and conduit assembly 22 is placed partially through top wall of perimeter walls 20.

The distribution tubes 21 are placed vertically above the tube bundle 12 and are preferably placed in a row along transversal direction with respect to longitudinal axis A, i.e. they are placed at the same height. More preferably, they are displaced at the same transversal distance one with resect to the other, i.e. they are spaced transversally of the same distance.

The support structure 13 further comprises transversal walls 23 provided with a plurality of openings 24, such openings 24 are designed to house tubes 12a of the tube bundle 12 in order to provide to this latter support/guide along space 3.

According to the above described topology of the tubes 12a of tube bundle 12, the support structure 13 comprises a plurality of first transversal walls 23' to support/guide first tubes group 12' , a plurality of second transversal walls 23' ' to support/guide second tubes group 12' ' , a plurality of third transversal walls 23' ' ' to support/guide first tubes group 12' ' ' and a plurality of fourth transversal walls 23' ' ' ' to support/guide first tubes group 12' ' ' ' .

The support structure 13 further comprises at least a longitudinal wall 24 extending parallel to longitudinal axis A in order to transversally subdivide space 16. In the described example, the support structure 13 comprises a pair of longitudinal walls 24 that divides space 16 into a pair of lateral portions that have the same transversal extension and a central portion that has a greater transversal extension with respect to lateral portions.

Preferably, longitudinal walls 24, and in case, lateral portion of perimeter wall 20, are provided with cantilevered walls 25 extending transversally from the longitudinal wall 24 inclined towards bottom portion of space 3 with respect to vertical axis D. In the disclosed embodiment each longitudinal wall 24 and the lateral portion of perimeter wall 20 comprises a pair of cantilevered walls 25 that are vertically equally spaced one with respect to the other, i.e. they are placed in two rows. In particular, both sides of a longitudinal wall 24 is provided with cantilevered walls 25.

Preferably, longitudinal walls 24 are provided with openings 26 to allow fluidic communication between the above described portions of space 16.

The hybrid evaporation module further comprises a demister mesh 27 that is preferably carried by the support structure 13.

In particular, the demister mesh 27 is vertically placed between the bottom of the space 3 and the fourth tubes group 12' ' ' ' and carried by perimeter wall outside space 16, i.e. radially comprised between the perimeter wall 20 and intermediate portion 2a of housing 2.

The demister mesh 27 defines a plurality of openings 28 disposed into a web and configured to avoid the passage of drops from the bottom portion of space 3 and the first manifold 6.

Advantageously, the demister mesh 27 comprises sealing walls 29 extending vertically, i.e. along vertical axis D and configured to cooperate by contact with perimeter wall 20 and the inner surface of the intermediate proton 2a in order to allow fluidic communication only through the demister mesh 27.

The aforementioned walls may be realized separately and fixed together or being realized, at least some among them, as one piece

The hybrid evaporation module 10 further comprises a distributor plenum 31 vertically interposed within the tube bundle 12 and configured to distribute refrigerant fluid along said vertical axis D direction.

In particular, the distributor plenum 31 is housed within space 16 and vertically comprises between the first and second tubes groups 12' , 12' ' and laterally in contact with perimeter wall 20 so that refrigerant fluid is forced to pass through the distributor plenum 31.

Distributor plenum 31 comprises a plate element 32 extending along axis A and provided with a pair of lateral portion 32a with respect to longitudinal axis A and a central portion 32b laterally comprised by lateral portion 32a.

The central portion 32b is provided with a mesh of openings 33 distributed along all the area of the central portion 32b.

Advantageously, such openings 33 may have different diameters or may be distances with variable distances in function of the distance of the opening 33 with respect to outlet opening 4 in order to allow uniform distribution of the refrigerant fluid in counter action to the sucking pressure coming from outlet opening.

Accordingly, openings 33 that are nearer to the opening 4 may be smaller in diameter or have less density (i.e. they can be more distanced one with respect to the other) with respect to openings 33 that are more distant with respect to opening 4.

The lateral portions 32a have advantageously the same shape, i.e. they have a vertically variable profile configured to collect refrigerant fluid towards the central portion 32b. In particular, the variable profile is a linear profile that has the greatest height along vertical axis D in contact to perimeter wall 20 decreasing linearly till reaching the height of the central portion 32b.

The hybrid evaporation module 10 further comprises oil separation means 37 configured to improve oil separation with respect to the refrigerant fluid flow.

In particular, such oil separation means 37 comprises a pair of longitudinal walls 38 extending on at least part, preferably entirely, on the longitudinal axis direction within intermediate portion 2a of housing 2. Preferably, walls 38 are two and placed on opposite sides with respect to axis D, more preferably at the same distance thereof.

As exemplarily shown, the walls 38 are placed within the third tubes group 12' ' ' and extends from a lower portion of the intermediate portion 2a. In particular, the walls 38 each comprise a lower portion that extends radially with respect to the lower surface of intermediate portion 2a and an upper portion 38' ' that extends from the lower portion 38' in a direction parallel to vertical axis D.

It is furthermore noticed that the structure of the hybrid evaporation module 10 is symmetric with respect to vertical axis D and with respect to longitudinal axis A, i.e. the half of hybrid evaporation module 10 on the left with respect to vertical axis D is equal to the right half and the half of hybrid evaporation module 10 on the rear with respect to longitudinal axis A is equal to the front half.

The hybrid evaporation module 10 may further comprises ventilation plate 35 arranged within space 3 in proximity of first manifold 6 and configured to avoid direct sucking of the gaseous phase refrigerant flow from this latter, i.e. it forces the passage of refrigerant flow about the ventilation plate 35 before reaching the first manifold 6.

In greater detail, the ventilation plate 35 comprises a wall 36 that extends parallel to axis C direction from support structure 13 within space 3. In particular, the wall 36 extends perpendicularly from lateral walls of perimeter walls 30 above the fourth tubes group If' ' ' ' , i.e. just beneath the top portion of perimeter wall.

Preferably, the wall 36 has a variable length profile in the transversal direction of axis C, wherein the maximum transversal extension is in proximity of the first manifold 6 and the minimum extension is in the terminal longitudinal portions of the wall 36. Making reference to figures 3 to 5, particular details of distributor 11 are visible.

In particular, in the enlarged portion of figure 3, it can be appreciated that the conduits 21 comprises openings 40 configured to allow the distribution of the refrigerant on the below tube bundle 12.

Preferably, such openings 40 are realized on a bottom portion of the conduits 21 and they are all along the same line, i.e. they run parallel on the bottom portion of the conduits 21 with respect to longitudinal axis A.

In particular, the openings 40 have preferably an oblong shape wherein the main opening direction of each opening 40 is parallel to longitudinal axis A.

Furthermore, the opening 40 may have a variable opening area in function of their distance with respect to conduit assembly 22, i.e. they can have a greater area as more each opening is distant with respect to conduit assembly 22. In this way, the refrigerant fluid may be distributed uniformly.

In particular, such openings are symmetrically distributed with respect to axis C of conduit assembly 22 so that the refrigerant fluid is uniformly distributed along axis A.

As better shown in figures 4 and 5, the conduit assembly 22 comprises an external housing 22a that is rigidly connected to the distribution conduits 21 in an intermediate position with respect to their longitudinal extension along axis A and that is coupled to the manifold 7 defining the opening 5.

The distribution conduits 21 are furthermore connected together thanks to terminal transversal elements 41 and intermediate transversal elements 42, preferably both shaped as rectangular plates, extending parallel to axis C and defining plurality of openings configured to house the distribution conduits 21. In particular, the terminal transversal elements 41 defines blind openings configured to house the distribution conduits 21 and acting as a plug while the intermediate transversal elements 42 define trough openings configured to provide a support for the conduits 21 housed therein.

The external housing 22a further defines a pair of plurality of inner openings 43 configured to allow the fluidic communication of the external housing 22a with the distribution conduits 21. According to the disposition of the distribution conduits 21, the openings 43 are placed linearly parallel to axis C in two opposite rows with respect to axis C.

The conduit assembly 22 may further comprise an inner housing 22b that is dimensioned so as to be inserted within external housing 22a in tight manner. The inner housing 22b may be selectively fixed to external housing 22a, in particular to manifold 7, via fixation means such as threaded elements in at least an angular preset position with respect to axis C.

The inner housing 22b defines at least a first pair of plurality of openings 44 that are longitudinally spaced along axis C direction in order to match with inner openings 43 of external housing 22a. The inner housing 22b may define also further pairs of plurality of openings 44 opposed in diameter direction one with respect to the other.

The openings 44 of each pair of openings in inner housing 22b and/or the inner openings 43 of external housing 22a may have different diameter one with respect to the other along axis C direction in order to uniform the refrigerant fluid distribution to distribution conduits 21.

The conduit assembly 22 may further comprise a distribution plate 22e carried by a flanged portion 22d configured to be connected to a coupling portion 22c of the manifold 7 and configured to be fluidly interposed on the opening 5. The distribution plate 22e defines a plurality of openings (not shown) configured to uniform the distribution of refrigerant fluid within the inner housing 22b. The openings can be optimized in function of the typology of refrigerant fluid used in the conditioning circuit.

The operation of the above described hybrid assembly 1 is the following.

Making reference to figure 2, it is noticed that, summarizing, refrigerant fluid passes from conduit assembly 22 towards distribution conduits 21, through tube bundle 12 and evaporates; such gaseous phase of refrigerant fluid is sucked by first manifold 6.

In greater detail, distribution conduits 22 flow the refrigerant fluid above the tube bundle 12. The refrigerant fluid is uniformly distributed on the upper tubes 12a and flows down tube by tube. During the passage through the tube bundle 12, it exchange heat through the external surface of tubes 12a with the operative fluid flowing therein, cooling this latter. The refrigerant fluid then collects in lower portion of space 3 flooding the lowest tubes 12a and continuing to exchange heat which this latter.

During the passage in the tube bundle 12, the cantilevered portions 25 help to avoid that refrigerant fluid tends to flow on longitudinal walls 24 or in perimeter walls 20. The same longitudinal walls 24 avoid that too much refrigerant fluid passes between central portion of space 16 and lateral portions of space 16.

The distribution plenum 31 further optimizes the refrigerant flow distribution, in particular avoiding an excessive flow passage in proximity of first manifold 6.

When evaporating, the gaseous phase refrigerant passes through the demister mesh 27, thereby reducing the possibility that liquid phase refrigerant may flow towards first manifold 6.

Following to the above passage, the gaseous phase refrigerant passes through the forth tubes group 12 thereby overheating and further avoiding that liquid phase refrigerant may flow towards the first manifold 6.

According to the above, it is clear that refrigerant fluid is evaporated and overheated thanks to the hybrid evaporation module 10.

In greater particular, during assembly of the evaporator assembly 1, the conduit 22 may be optimized for the peculiar typology of refrigerant fluid.

Indeed, the inner housing 22b and the distribution plate 22e can be substituted according to the specific refrigerant fluid so that their openings are optimized for such fluid. In case the inner housing 22b is provided with a plurality of pair of openings, only distribution plate 22e may be substituted and the inner housing 22b can be rotated to associate the correct openings 44 in communication with openings 43. In such case, angular references can be provided on the manifold 7 or on inner housing 22b.

In view of the foregoing, the advantages of an evaporator assembly 1 according to the invention are apparent .

The presence of the falling flow of refrigerant on tube bundle, optimized thanks to the different elements of the hybrid evaporation module 10 allows to reduce the refrigerant load, thereby increasing the efficiency of the evaporator ass e mb 1 y .

The presence of the demister mesh combined with the perimeter walls clearly divides the liguid-phase portion of space 3 with respect to the gaseous phase portion of space 3, thereby avoiding passage of fluid to first manifold 6.

The presence of the flooded portion in the bottom portion of space 3 allows to evaporate all refrigerant fluid and to provide a reservoir of refrigerant fluid for operational necessities.

The symmetric layout of hybrid evaporation module 10 improves the space optimization of the hybrid evaporation module 10 allowing a reduction of space an weight. Moreover, the symmetric layout improves the fluid distribution and the evaporated fluid suction.

The fact that the first and second manifolds 6, 7 are realized laterally with respect to vertical axis of the evaporator assembly 1 facilitates the installation with other elements of the refrigeration assembly.

The presence of the mesh demister interposed between the inner surface of the housing 2 and the perimeter wall 20, allows to delimit the above mentioned liquid-gaseous phase portion of space 3, avoiding liquid passage towards first manifold 6.

The presence of fourth tubes group 12' ' ' ' allows to overheat evaporated gas before suction by outlet conduit, further reducing the possibility of suction of liquid refrigerant .

The ventilation plate 35 further avoid the liquid suction by making uniform the suction flow coming from outlet conduit, thereby improving evaporator gaseous flows towards this latter.

The presence of plenum 31 allows to uniform the distribution of refrigerant liquid flow coming from a portion of the tube bundle, in particular avoiding a preference of direction in proximity to outlet conduit.

In particular, the fact that plenum 31 is placed inside the space 16 delimited by structure 13 forces the liquid to fall within the flooded portion so that cannot pass directly to outlet conduit.

The conduit assembly 22 comprising a fixed portion provided with distribution tubes 21 and a variable portion that can be inserted within the fixed portion allows to optimized the fluid distribution according to peculiar load of the machine or to a peculiar refrigerant fluid.

In particular, it is sufficient to substitute/rotate the inner housing 22b and to change the distribution plate 22e to vary the title of refrigerant fluid that is distributed to the distribution conduit .

Similarly, the variable area openings in conduits 43 , 44 and 40 allows to uniformly distribute the refrigerant fluid along axis A and C of the refrigerant fluid.

According to the above, by simply changing the variable portion of the conduit assembly 22 it is possible to optimi ze the refrigerant assembly 1 to a di fferent operation standard and/or to a dif ferent refrigerant fluid . Accordingly, design costs and versatility of the refrigerant is increased .

It is clear that modifications can be made to the described evaporator assembly 1 which do not extend beyond the scope of protection defined by the claims .

For example, the tube bundle 12 may have a dif ferent topology of tubes 12a that may have dif ferent shapes . Similar consideration may apply to distribution conduits 21 .

Similarly, support structure 13 may have a dif ferent shape and/or its elements may be realized with di fferent geometries or reali zed in many or single pieces connected among them.

The described openings in some elements may have di fferent geometry or distribution with respect to the shown one .

In general , housing 2 may have a di fferent shape and more evaporator assembly 1 can be linearly coupled as show in the attached drawings .

Claims

1.- Evaporator assembly (1) for evaporating a refrigerant fluid of a refrigerant arrangement, said evaporator assembly (1) comprising a housing (2) defining a space (3) extending along a longitudinal axis (A) , said evaporator (1) comprising an inlet manifold (7) configured to allow the insertion of said refrigerant fluid in liquid state and an outlet manifold (6) configured to allow the suction of said refrigerant fluid in gaseous state, said outlet and inlet manifolds (6, 7) being disposed inclined with respect to a vertical axis (D) of said evaporator assembly (1) perpendicular to said longitudinal axis (A) , said evaporator assembly (1) comprising a hybrid evaporation module (10) housed within said space (3) and comprising a tube bundle (12) provided with a plurality of tubes (12a) configured to allow the passage of an operative fluid, a support structure (13) and a distributor (11) wherein said support structure (13) defines a space (16) housing at least part (12' , 12 ' ' ) of said tubes (12a) , wherein said distributor (11) comprises a conduit assembly (22) at least partially housed within said space (16) and passing through said inlet manifold (7) and extending along a transversal axis (C) perpendicular to said longitudinal and vertical axis (A, D) , said distributor (11) further comprises a plurality of distribution conduits (21) housed within said space (16) and extending along said longitudinal axis (A) from said conduit (22) and provided with openings to distribute liquid refrigerant fluid above said tube bundle (12) , wherein said conduit assembly (22) is positioned in a middle position along said longitudinal axis (A) and wherein said distribution conduits (21) extends above said tube bundle ( 12 ) , said distribution conduits (21) being disposed in a symmetric manner with respect to said transversal axis (C) and said vertical axis (D) .

2.- Evaporator assembly according to claim 1, wherein said conduit assembly (22) comprises an external housing (22a) fixedly connected to said distribution conduits (21) and an inner housing (22b) configured to be selectively housed within said external housing (22a) through said inlet manifold (7) , said external housing (22a) and said inner housing (22b) being provided with openings (43, 44) in fluid communication with said distribution conduits (21) .

3.- Evaporator assembly according to claim 2, wherein said at least one between the openings (43) on said external housing (22a) and the openings (44) on said inner housing (22b) have a variable dimension according to their position along said transversal axis (C) .

4.- Evaporator assembly according to claims 2 and 3, wherein said openings (43, 44) are disposed in a pair of plurality of openings, said pair of openings being disposed one opposed to the other in diameter direction and being disposed linearly parallel to said transversal axis (C) direction .

5.- Evaporator according to claim 4, wherein said inner housing (22b) comprises a plurality of pairs of openings each pair being angularly displaced with respect to the other with respect to said transversal axis (C) .

6.- Evaporator according to any of said preceding claims, wherein said conduit assembly (22) comprises a distribution plate (22e) configured to be selectively fluidly interposed between said external housing (22a) and said conduits (21) .

7.- Evaporator according to claim 6, wherein said distribution plate (22e) defines a plurality of openings to distribute said refrigerant fluid within said inner housing (22b) .

8.- Evaporator according to any of the preceding claims, wherein said distribution conduits (21) are connected 19 together by a pair of terminal transversal elements (41) connected to terminal portions of said distribution conduits .

9.- Evaporator according to any of the preceding claims, wherein said distribution conduits (21) are connected together by a plurality of transversal elements (42) spaced along said longitudinal axis (A) between terminal portions of said distribution conduits (21) .

10.- Evaporator according to any of the preceding claims, wherein said distribution conduits (22) comprises a plurality of openings (40) faced to said tube bundle (12) and configured to allow flowing of said refrigerant fluid on said tubes (12a) of said tube bundle (12) .

11.- Evaporator according to claim 10, wherein said openings (40) have a variable dimension in function of their positioning along said longitudinal axis (A) .