EVAPORATOR

Abstract

An evaporator includes an enclosure with a lateral confinement shell with a substantially horizontal axis, which internally accommodates a dispenser of a coolant fluid and at least one tube bundle, which is arranged below the dispenser. The evaporator further includes exchanger tubes, which are passed through by a fluid to be cooled. At least one first group of exchanger tubes is arranged along rows which extend on substantially horizontal and mutually superimposed planes. The exchanger tubes of each row are arranged in at least one respective tray for collecting and distributing the liquid coolant fluid. Each tray has, along at least one first longitudinal edge, at least one first containment sidewall which is adapted to allow the liquid coolant fluid contained therein to fall by overflowing into an underlying tray and is provided in its bottom with openings for draining the liquid coolant fluid.

Claims

1-14. (canceled)

15. An evaporator comprising: an enclosure having a lateral confinement shell with a substantially horizontal axis, which internally accommodates a dispenser of a liquid coolant fluid and at least one tube bundle, which is arranged below said dispenser and comprises a plurality of exchanger tubes which extend substantially parallel to the axis of said shell and are configured to be passed through by a fluid to be cooled, at least one first group of said exchanger tubes being arranged along rows which extend on substantially horizontal and mutually superimposed planes, wherein the exchanger tubes of each one of said rows are arranged in at least one respective tray, which is adapted to collect the liquid coolant fluid in order to keep the exchanger tubes of each one of said rows at least partially immersed in said liquid coolant fluid, each one of the trays having, along at least one first longitudinal edge, at least one first containment sidewall which is adapted to allow the liquid coolant fluid contained therein to fall by overflowing into an underlying tray and is provided in its bottom with a plurality of openings for draining the liquid coolant fluid, which are arranged at the exchanger tubes of the underlying tray in order to allow the liquid coolant fluid to fall from each tray onto the outer surface of the exchanger tubes of the underlying tray.

16. The evaporator according to claim 15, wherein each tray is provided with a second containment sidewall which extends upward to contain at least partially the overlying tray.

17. The evaporator according to claim 16, wherein said second containment sidewall is arranged along a second longitudinal edge of the corresponding tray which lies opposite with respect to said first longitudinal edge.

18. The evaporator according to claim 16, wherein said second containment sidewall has a portion having an extension inclined towards the outside of the corresponding tray.

19. The evaporator according to claim 15, wherein said trays have, in mutual alternation, in succession, said first longitudinal edge directed towards one side of said shell or towards the opposite side.

20. The evaporator according to claim 15, wherein said openings for draining have a size that is calibrated to balance a quantity of liquid coolant fluid that enters each tray with a quantity of coolant fluid that exits in vapor form from each tray.

21. The evaporator according to claim 15, wherein a size of said openings for draining is different from tray to tray.

22. The evaporator according to claim 15, further comprising, for each tray, means of flow control configured to move on command and adapted to affect at least partially said openings for draining.

23. The evaporator according to claim 15, wherein each tray is mounted stacked by interlocking on an underlying tray to provide a load-bearing structure for at least the exchanger tubes of said first group of exchanger tubes.

24. The evaporator according to claim 15, wherein each tray has at least one supporting partition which defines at least one positioning abutment for an overlying tray.

25. The evaporator according to claim 15, wherein each tray has, at first and second tray ends arranged along its longitudinal axis that is parallel to the axis of said shell, containment end walls which define receptacles for the respective exchanger tubes.

26. The evaporator according to claim 15, further comprising, at least one shielding wall disposed inside said shell and laterally to said tube bundle, said at least one shielding wall extends downward and defines, for the vapor of said coolant fluid that exits from said trays, at least one first flow channel which extends downward and is delimited between said tube bundle and said at least one shielding wall and at least one second flow channel which extends upward and is delimited between said shell and said shielding wall.

27. The evaporator according to claim 15, further comprising a second group of exchanger tubes disposed below said first group of exchanger tubes, said second group of exchanger tubes is configured to cause the evaporation of the excess liquid coolant fluid collected in the lower part of said shell.

28. The evaporator according to claim 15, wherein at least one discharge outlet configured for the extraction of oil is disposed in a lower part of said shell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Further characteristics and advantages of the disclosure will become better apparent from the description of some preferred, but not exclusive, embodiments of the evaporator according to the disclosure, which are illustrated for the purposes of non-limiting example in the accompanying drawings wherein:

[0027] FIG. 1 is a perspective view of the evaporator according to the disclosure;

[0028] FIG. 2 is a perspective and longitudinal cross-sectional view of the evaporator according to the disclosure;

[0029] FIG. 3 is a perspective and longitudinal cross-sectional view of the evaporator according to the disclosure from which the shell, the dispenser and a shielding wall have been omitted, in order to better show the interior of the evaporator;

[0030] FIG. 4 is a perspective view of the evaporator according to the disclosure with the shell omitted;

[0031] FIG. 5 is a perspective view of a tray for collecting and distributing the cooling liquid belonging to the evaporator according to the disclosure with a row of exchanger tubes that are associated therewith;

[0032] FIG. 6 is a perspective view of a tray of the evaporator according to the disclosure without the exchanger tubes;

[0033] FIG. 7 is a longitudinal cross-sectional view of the evaporator according to the disclosure;

[0034] FIG. 8 is a transverse cross-sectional view of a detail of the evaporator according to the disclosure;

[0035] FIG. 9 is a perspective and longitudinal cross-sectional view of the dispenser of coolant fluid arranged inside of the evaporator according to the disclosure;

[0036] FIG. 10 is a cross-sectional view of some exchanger tubes of the evaporator according to the disclosure;

[0037] FIG. 11 is a transverse cross-sectional view of the evaporator according to the disclosure;

[0038] FIG. 12 is a perspective and transverse cross-sectional view of the evaporator according to the disclosure;

[0039] FIG. 13 is a perspective and transverse cross-sectional view from a different angle with respect to FIG. 12 of the evaporator according to the disclosure;

[0040] FIG. 14 is a perspective view of different embodiment of the evaporator according to the disclosure, with several components omitted in order to show a first group of exchanger tubes and the corresponding trays; and

[0041] FIG. 15 is an enlarged-scale detail of FIG. 14;

[0042] FIG. 16 is a schematic perspective view of a possible embodiment of the trays for collecting and distributing the liquid coolant fluid, in a condition of operation;

[0043] FIG. 17 is a transverse cross-sectional view of the tray in FIG. 16;

[0044] FIG. 18 is a schematic perspective view of the embodiment in FIG. 16 in a different condition of operation; and

[0045] FIG. 19 is a transverse cross-sectional view of the tray in FIG. 18.

DETAILED DESCRIPTION OF THE DRAWINGS

[0046] With reference to the figures, the evaporator according to the disclosure, generally designated by the reference numeral 1, comprises an enclosure 2 which is provided with a lateral confinement shell 3 with a substantially horizontal axis, which internally defines a heat exchange chamber 3a.

[0047] Accommodated inside the shell 3 is a dispenser 4, the function of which is to introduce a coolant fluid into the heat exchange chamber 3a of the shell 3, such fluid being fed to the dispenser 4 by way of a connector 5 passing through the shell 3. It should be noted that the coolant fluid that is fed to the dispenser 4 is, generally, in a biphasic condition, i.e. it is made up of a liquid phase, hereinafter referred to as liquid coolant fluid, and by a vapor phase, hereinafter referred to as vapor of the coolant fluid.

[0048] Also accommodated inside the shell 3 is at least one tube bundle 6, which is arranged below the dispenser 4 and which comprises a plurality of exchanger tubes 7, which extend substantially parallel to the axis of the shell 3.

[0049] For example, the dispenser 4 comprises a distribution duct 4a, which extends substantially parallel to the axis of the shell 3 and is connected to the connector 5, by way of an own intake port 5a, which is arranged substantially in a central position along its longitudinal extension. Conveniently, the distribution duct 4a has a polygonal cross-section, with a flat lower wall 4b which has a plurality of delivery openings 4c from which the coolant fluid is drained downward in the direction of the tube bundle 6.

[0050] The exchanger tubes 7 are designed to be passed through by a fluid to be cooled, which is constituted, for example, by water or by an aqueous solution.

[0051] Conveniently, the shell 3 is closed, at one end, by a first head 8a, which is provided with an entry connection 9a and with an exit connection 9b for the fluid to be cooled, and, at its opposite end, by a second head 8b. Defined inside the first head 8a and the second head and 8b are channels 10 for the fluid to be cooled to circulate, which are connected to the inside of the exchanger tubes 7, in order to allow the fluid to be cooled, once it is introduced into the shell 3 through the entry connection 9a, to follow a path, inside the exchanger tubes 7, with various passes along the longitudinal extension of the shell 3, prior to exiting from the wall through the exit connection 9b, as shown schematically in FIG. 7.

[0052] Also inside the shell 3 there is a plurality of trays 11 for collecting and distributing the liquid coolant fluid, at least some of which are arranged one over the other.

[0053] In more detail, the tube bundle 6 comprises at least one first group of exchanger tubes 7 which is arranged along rows which extend on substantially horizontal and mutually superimposed planes.

[0054] In particular, the exchanger tubes 7 of each one of these rows are arranged in at least one respective tray 11, which is adapted to collect the liquid coolant fluid, so as to be able to keep the exchanger tubes 7 of each row at least partially immersed in the liquid coolant fluid, and to distribute it in the exchanger tubes 7 which are arranged in an underlying tray 11.

[0055] More specifically, according to the disclosure, each tray 11 has, along at least one first longitudinal edge, at least one first containment sidewall 12 which is adapted to allow the liquid coolant fluid contained therein to fall by overflowing into an underlying tray 11.

[0056] Also according to the disclosure, each tray is furthermore provided in its bottom 11a with a plurality of openings for draining 11b the liquid coolant fluid, such holes being arranged at the exchanger tubes 7 contained in the underlying tray 11 in order to allow the fall of the liquid coolant fluid from each tray 11 onto the outer surface of the exchanger tubes 7 placed below it.

[0057] In this manner, an optimal distribution is ensured of the liquid coolant fluid onto the exchanger tubes 7 in that the liquid coolant fluid is supplied around the exchanger tubes 7 in two ways i.e. not only by way of its falling by overflowing over the side of the overlying tray 11 but also by way of its falling through the openings for draining 11b of the overlying tray 11.

[0058] Advantageously, each tray 11 is furthermore provided with a second containment sidewall 13, which extends upward so as to contain, at least partially, the overlying tray 11. Conveniently, such second containment sidewall 13 is arranged along a second longitudinal edge of the tray 11, opposite to the first longitudinal edge along which the first containment sidewall 12 is present.

[0059] Advantageously, the second containment sidewall 13 has a portion, the extension of which is inclined toward the outside of the corresponding tray 11, which conveniently is connected to a vertical portion that protrudes upward from the bottom 11a of the tray 11 so as to create, between the second containment sidewall 13 of each tray 11 and the overlying tray 11, a space for the outflow of the vapor produced by the boiling of the liquid coolant fluid contained in each tray 11.

[0060] It should be noted that in the figures and, in particular, in FIGS. 8, 10 and 11, the path of the liquid coolant fluid inside the shell 3 is indicated with arrows with dotted lines, while the path of the vapor of the coolant fluid is indicated with arrows with continuous lines.

[0061] Conveniently, in their succession along a vertical direction, the trays 11 present their first longitudinal edge, with the corresponding first containment sidewall 12, alternately directed toward one side of the shell 3 or toward the opposite side.

[0062] Such alternating arrangement, toward one side or the other of the shell 3, of the first containment sidewall 12 of the various trays 11 allows an arrangement of the exchanger tubes 7 that is square or rectangular, when seen in transverse cross-section, with the consequence of enabling the positioning in the shell 3 of a greater number of exchanger tubes 7 with respect to triangular arrangements, as in the prior art.

[0063] It should be furthermore noted that, in their mutual arrangement, the trays 11 have the corresponding first containment sidewall 12 arranged laterally spaced apart toward the inside of the shell 3 with respect to the second confinement sidewall 13 of the underlying tray 11, so that the liquid coolant fluid overflowing from each tray 11 over the corresponding first containment sidewall 12 can fall, without losses, into the underlying tray 11.

[0064] Conveniently, the openings for draining 11b defined in the bottom 11a of the trays 11 have a size that is calibrated to balance the quantity of liquid coolant fluid that enters each tray 11 with the quantity of coolant fluid that exits in vapor form from each tray 11. To this end, equal importance lies with the total passage section made available for the liquid coolant fluid by the set of the openings for draining 11b, in combination with the size of each one of these openings.

[0065] In this manner, the heat exchange is ensured between the exchanger tubes 7 and the liquid coolant fluid according to a method typical of evaporators of the film falling type, and a supply to the underlying trays is ensured even when operating under a partial load.

[0066] Advantageously, the size of the openings for draining 11b can be the same for all the trays 11 or different from tray to tray. In particular, the sizes of the openings for draining 11b can conveniently vary substantially from 1 mm to 20 mm.

[0067] For example, it is possible for the size of the openings for draining 11b to progressively decrease starting from the tray 11 located highest and proceeding progressively toward the tray located lowest.

[0068] It is also possible for each tray 11 to provide means of flow control which are adapted to at least partially block the openings for draining 11b and can move on command in order to vary the degree of opening of the openings for draining 11b. For example, such means of flow control can comprise, for each tray 11, a plate 110 which is provided with passage openings 111, which have, conveniently, a size and an arrangement that are substantially the same as the openings for draining 11b. In particular, the plate 110 is slideably mounted with respect to the bottom 11a of the respective tray 11 in order to pass from a first condition, shown in FIGS. 18 and 19, in which its passage openings 111 are arranged in alignment with the openings for draining 11b of the corresponding tray 11, to at least one second condition, shown in FIGS. 16 and 17, in which the plate 110 at least partially occludes the openings for draining 11b of the corresponding tray 11b, and vice versa.

[0069] According to the preferred embodiment, each tray 11 is stacked by interlocking on the underlying tray 11, advantageously without requiring welding or other types of fixing, so as to provide a supporting structure capable of supporting at least the exchanger tubes 7 of the first group.

[0070] Conveniently, the trays 11 are arranged alternately staggered toward one side or toward the other side of the shell 3, so as to create between each tray 11 and the overlying tray the space for the passage of the liquid coolant fluid overflowing over the first confinement sidewall 12 of the overlying tray and for the egress from each tray 11 of the vapor of the coolant fluid.

[0071] In greater detail, as shown in FIGS. 5 and 6, each tray 11, at its longitudinal ends, arranged along its axis of extension parallel to the axis of the shell 3, is provided, advantageously, with containment end walls 14 which define receptacles 15 for the respective exchanger tubes 7, which are constituted by holes that are passed through hermetically by the exchanger tubes 7, so that each tray 11 can also act as a support per the corresponding exchanger tubes 7.

[0072] Advantageously, the trays 11 are provided with the same shape and each one is arranged rotated by 180 about a vertical axis with respect to the two contiguous ones, in succession along the direction of stacking, so as to alternately present the first containment sidewall 12 toward one side or toward the other side of the shell 3.

[0073] In more detail, each tray 11 is provided with at least one supporting partition 16 for the overlying tray 11.

[0074] More preferably, each tray 11 has a pair of supporting partitions 16, which are arranged at its opposing longitudinal ends and are preferably defined continuously with the containment end walls 14. Each one of such supporting partitions 16 protrudes laterally outward with respect to the first confinement sidewall 12 of each tray 11.

[0075] Conveniently, in their upper part, such supporting partitions 16 define a positioning abutment for the tray 11 stacked on top of the corresponding tray 11. In particular, the supporting partitions 16 define, in a position laterally spaced apart and outward with respect to the first containment sidewall 12 of the corresponding tray 11, at least one lateral abutment shoulder 16a, on which the second confinement sidewall 13 of the tray 11 stacked above is placed, so as to ensure the arrangement in a mutually spaced apart position between the first confinement sidewall 12 of each tray 11 and the second confinement sidewall 13 of the underlying tray.

[0076] The vapor produced by the boiling of the liquid coolant fluid is conveyed outside the shell 3 by way of an exit connector 17 defined in the upper part of the shell 3.

[0077] Advantageously, inside the shell 3 and laterally to the tube bundle 6, there is at least one shielding wall 18, which makes it possible to prevent the egress, by way of an exit connector 17, of droplets of liquid together with the vapor of the coolant fluid.

[0078] Preferably, the shielding wall 18 extends downward, with two portions that are mutually opposite with respect to the tube bundle 6, and defines, for the vapor of the coolant fluid exiting from the trays 11, at least one respective first flow channel 18a and at least one respective second flow channel 18b. In particular, the first flow channel 18a extends downward and is delimited between the tube bundle 6 and the shielding wall 18, while the second flow channel 18b extends upward and is delimited between the shell 3 and the shielding wall 18.

[0079] Conveniently, the shielding wall is arc-shaped with the concavity directed toward the tube bundle 6 so as to cover the upper part thereof and at least partially the lateral part thereof and is passed through by the intake port 5a of the distribution duct 4a. Conveniently, the shielding wall 18 is supported at its longitudinal ends by a pair of tuyere plates 19a and 19b, between which the shell 3 is interposed and to which the heads 8a and 8b are fixed, on the side thereof opposite the shell 3.

[0080] Advantageously, below the first group of exchanger tubes 7 i.e. the exchanger tubes 7 arranged in the trays 11, there can also be a second group of exchanger tubes 7, proximate to the bottom of the shell 3, which are designed to evaporate the excess liquid coolant fluid that collects in the lower part of the shell 3. In this manner, there is no need to install a pump or an ejection system to make the liquid coolant fluid recirculate from the bottom of the shell to the connector 5.

[0081] It should be added that it is also possible to arrange two or more trays 11 arranged mutually laterally adjacent on respective horizontal levels in order to accommodate the same row of exchanger tubes 7, if it is intended to use exchanger tubes 7 that are longer than the longitudinal extension of the single trays 11, as shown in particular in FIGS. 14 and 15.

[0082] For the sake of completeness it should be added that in the lower part of the shell 3, preferably below the second group of exchanger tubes 7, there is, advantageously, at least one discharge outlet 20, which is provided, conveniently, with an adapted connector 21, in order to allow, in the eventuality that the evaporator is used in refrigeration systems in which oil-lubricated compressors are used, the extraction from the shell 3 of the oil originating from the compressor, so as to permit the return of same to the compressor.

[0083] Operation of the evaporator, according to the disclosure, is the following.

[0084] The coolant fluid, generally in the form of a biphasic mixture composed of a liquid phase and a vapor phase, enters, from the upper part of the shell 3, through the connector 5, into the dispenser 4, feeding the distribution duct 4a, from which it exits, through the delivery openings 4c, so as to be evenly distributed in the first tray 11 which is arranged higher than the others.

[0085] The fluid to be cooled is made to enter the shell 3, through the entry connection 9a, so that it can run through the exchanger tubes 7 until it arrives at the exit connection as shown in FIG. 7, where arrows show the possible path of the fluid to be cooled.

[0086] In the first tray 11, the coolant fluid, coming into contact with the exchanger tubes 7 passed through by the fluid to be cooled, starts to evaporate and the two phases, vapor and liquid, of the coolant fluid separate, following different paths.

[0087] The liquid coolant fluid, which does not evaporate, falls onto the row of exchanger tubes 7 arranged in the second tray 11, arranged below the first tray 11, in two possible ways: either by overflowing over the first confinement sidewall 12 or by passing through the openings for draining 11b.

[0088] In particular, when the level of liquid coolant fluid in the first tray 11 exceeds the height of the first confinement sidewall 12, a part of the liquid coolant fluid falls into the second tray 11 by overflowing, while another part of the liquid coolant fluid can fall at each exchanger tube 7 of the underlying row arranged in the second tray 11, through the openings for draining 11b arranged on the bottom 11a of the first tray 11, as shown in FIG. 8, with a falling film operating method.

[0089] If, under partial load conditions, the level of liquid coolant fluid drops below the height of the first confinement sidewall 12, supply of the underlying tray 11 and therefore the wettability of the lower exchanger tubes 7 is still ensured by the openings for draining 11b.

[0090] In the same way, all the other trays 11 are progressively supplied, as shown in FIG. 10.

[0091] The coolant fluid that evaporates exits from the lateral parts of the trays 11 and, as shown in FIG. 11, is channeled into the first flow channels 18a, defined between the tube bundle 6 and the shielding wall 18, and, subsequently, into the second flow channels 18b, defined between the shielding wall 18 and the shell 3, before arriving at the top of the shell 3, from which it exits by way of the exit connector 17.

[0092] The liquid coolant fluid gathered in the bottom of the shell 3 is made to evaporate by the exchanger tubes 7 of the second group, with a pool boiling operating method.

[0093] In practice it has been found that the disclosure fully achieves the intended aim and objects, in that, by virtue of the presence of the trays provided with openings for draining and the possibility for the coolant liquid to overflow from them, it makes it possible to take better advantage of the exchange surface of the exchanger tubes with respect to a traditional falling film evaporator, and, by virtue of the openings for draining arranged on the bottom of the trays, it makes it possible to prevent, under partial load conditions, some rows of exchanger tubes from remaining dry, with a consequent improvement of the wettability of the exchanger tubes with respect to a traditional pool boiling evaporator as well.

[0094] Another advantage of the evaporator according to the disclosure is that it enables a reduction of the quantity of coolant required with respect to a pool boiling evaporator.

[0095] The disclosure, thus conceived, is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements.

[0096] In practice the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.

[0097] The disclosures in Italian Patent Application No. 102017000136156 from which this application claims priority are incorporated herein by reference.