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EP-4739439-A1 - SPRAYING MEANS IMPROVED FOR TUBE BUNDLE HEAT EXCHANGER

EP4739439A1EP 4739439 A1EP4739439 A1EP 4739439A1EP-4739439-A1

Abstract

The present invention relates to a nozzle suitable to be used in a tube bundle heat exchanger to spray uniformly a cooling fluid on such bundle.

Inventors

  • PROVENZIANI, FRANCO
  • PITRELLI, Paolo
  • Pagano, Luca

Assignees

  • Wieland Provides Srl

Dates

Publication Date
20260513
Application Date
20240626

Claims (20)

  1. 1. A nozzle for spraying a fluid, comprising: - a first wall (6a) preferably of substantially tubular shape, defining an axial direction (Y), a radial direction (A) and a circumferential direction, said first wall (6a) limiting an inner space (600) in said radial direction and having an outer surface (6a’), - a second wall (6b) having an inner surface (6b’), the second wall being arranged coaxial to the first wall (6a) and spaced apart on said radial direction from the outer surface (6a’) of the first wall (6a), - additional walls (6c, 6d) of which at least a lower one (6c) and at least an upper one (6d) extending between the first (6a) and the second wall (6b), - an annular chamber (60) arranged between the outer surface (6a’) of the first wall (6a) and the inner surface (6b’) of the second wall (6b) and limited on said axial direction by said at least an additional lower wall (6c) and said at least an additional upper wall (6d), - wherein on said first wall (6a) there is at least an opening (61 ) putting in communication said inner space (600) with said annular chamber (60) to allow the passage of said fluid from said inner space to said annular chamber, wherein on said second wall (6b) there are outlet means (62’, 62”) of said fluid which put into communication said annular chamber (60) with the outside surrounding said second wall (6b), said distribution means allowing to spray said fluid towards outside.
  2. 2. The nozzle according to claim 1 , wherein said outlet means (62’, 622”) and said at least an opening (61 ) are axially spaced apart with respect to each other.
  3. 3. The nozzle according to claim 2, wherein said outlet means (62’, 62”) face a section impermeable for said fluid of the outer surface (6a’) of said first wall (6a).
  4. 4. The nozzle according to claim 2, wherein said outlet means (62’, 62”) face a section impermeable for said fluid of at least one (6c, 6d) of said additional walls.
  5. 5. The nozzle according to claim 2, 3 or 4, wherein said at least an opening (61 ) faces a section impermeable for said inner surface (6b’) of said second wall (6b).
  6. 6. The nozzle according to claim 2, 3 or 4, wherein said at least an opening (61 ) faces a section impermeable for said fluid of at least one (6c, 6d) of said additional walls.
  7. 7. The nozzle according to any one of the preceding claims, wherein said at least an additional lower wall (6c) and at least an additional upper wall (6d) are arranged in radial direction, then perpendicularly to said first wall (6a).
  8. 8. The nozzle according to claim 7, comprising an upper wall (6d) and a lower wall (6c), wherein said outlet means (62’, 62”) is arranged in proximity to said upper wall (6d) or said lower wall (6c).
  9. 9. The nozzle according to claim 8, wherein said at least an opening (61 ) is arranged in proximity of said lower wall (6c) or said upper wall (6d).
  10. 10. The nozzle according to any one of the preceding claims wherein said second wall (6b) develops parallelly to said first wall (6a).
  11. 11. The nozzle according to any one of the preceding claims, wherein said first wall (6a) comprises one single opening with circumferentially arranged slot.
  12. 12. The nozzle according to any one of claims 1 to 10, wherein said first wall (6a) comprises a plurality of circumferentially arranged openings (61).
  13. 13. The nozzle according to claim 12, wherein such openings are through- holes (61 ).
  14. 14. The nozzle according to any one of the preceding claims, wherein said outlet means comprises one single circumferentially developing slot opening (62’).
  15. 15. The nozzle according to any one of claims 1 to 13, wherein said outlet means comprises a plurality of circumferentially arranged slots (62”).
  16. 16. The nozzle according to claim 15, wherein each one of said slots (62”) is arranged inclined with respect to a plane transversal to said axial direction.
  17. 17. The nozzle according to any one of the preceding claims, wherein said fluid is suitable to be used as cooling fluid in a heat exchanger and it is a fluid comprising a portion in gaseous form and a portion in liquid form.
  18. 18. Use of the nozzle according to any one of claims 1 to 17 in a heat exchanger used as evaporator.
  19. 19. A heat exchanger suitable to be used as evaporator comprising: a plurality of tubes (1 , T) arranged parallel to each other to define a bundle, the tubes having an outer surface; a distribution device (4, 4’) of a cooling fluid on said outer surface of said tubes, said distribution device having at least a conduit (43, 43’) developing at least partially into said tube bundle; said at least a conduit being provided with at least a nozzle according to any one of claims 1 to 17, wherein said at least a nozzle is arranged on said conduit to be placed inside said tube bundle at a respective spraying level.
  20. 20. The heat exchanger according to claim 19, wherein said nozzle is arranged to spray said fluid at least on tubes placed at or in proximity to said respective spraying level.

Description

SPRAYING MEANS IMPROVED FOR TUBE BUNDLE HEAT EXCHANGER DESCRIPTION Technical field of the invention The present invention relates to the field of the apparatuses for the heat treatment of fluids, in particular the apparatuses suitable to the use in industrial air conditioning systems. The present invention, more in detail, relates to a tube bundle heat exchanger, in particular an evaporator, and in particular to a nozzle used therein. Background As it is known, the tube bundle heat exchangers have several problems affecting the size and design of the evaporator. Generally, a problem of the evaporators is that of obtaining a wished thermal efficiency, sizes and technical complexity being equal. Therefore, a technical object is to increase the thermal efficiency of the heat exchanger with structurally simple and economically advantageous solutions. Several factors affect the efficiency of these machines. For example, one of the main operating limits of the evaporators, such as for example in the flooded and spray type evaporators, is represented by the dragging of a liquid component in the flow for sucking the fluid used as cooling fluid. In fact, this involves a loss in the available refrigeration capacity since if, on one side, a portion of the cooling fluid exits the evaporator in liquid phase the latter could not have contributed to the heat exchange, by affecting the apparatus efficiency. In the most serious cases, the liquid dragging involves further significant damages to the circuit placed downstream of the suction, in particular to the mechanics of the compression units. A known solution to avoid the liquid dragging provides to increase the overheating of the fluid during suction at the evaporator exit. This solution, although very effective and simple to be implemented (it does not require additional components) is very expensive since it involves an oversizing of the evaporator. In order to obtain the overheating of the cooling fluid, in fact, it is necessary to increase the heat exchange surfaces and then the overall sizes of the evaporator, by increasing considerably the costs. It is also known to size the evaporator in order to limit the liquid dragging and to keep the gas flows within predetermined conditions. Even in this case one proceeds with oversizing the evaporator and mechanical elements are used, suitable to uniform the inner gas flows. As for the previously described solution, by introducing additional inner components and/or by oversizing the sizes to reduce the suction flow speed, the evaporator cost increases. Other solutions provide the use of “intermediate” heat exchangers in order to dry the suction flow. In other words, the use of an additional heat exchanger, outer or inserted in the evaporator itself, is provided, in which the hot liquid coming from the high-pressure line circulates and so as to allow an additional heat exchange with the humid gas exiting the evaporator. At last, it is also known to use liquid separating means installed downstream of the suction, but upstream of the inlet in the compression units. Although these are generally cheap solutions, which operate well in protecting the compressor against high liquid dragging transients, these configurations are not useful in case the liquid dragging is constantly above a limit threshold. Moreover, although each one of the above-illustrated solutions can have advantages, all of them have in common the drawback of a not negligible cost increase, associated to the refrigerator implementation. Still, an additional factor affecting the exchanger efficiency is linked to the homogeneous spraying of the cooling fluid in general, even in particular of its liquid phase, on the tube bundle. In fact, if such homogeneous spraying does not take place, the wished heat exchange is not obtained. In standard flooded type evaporators the cooling fluid, generally sprayed from the bottom, submerges the tube bundle by favouring the liquid interaction with the exchange tubes to the detriment of the overall amount of charge the same. Within the evaporators of so-called “falling film” and “spray” type, according to the known solutions, the distribution of the cooling fluid mainly takes place from a portion above the tube bundle, in a spraying direction traditionally from top towards the bottom. However, this type of spraying does not solve the technical problem of spraying the fluid so that the tube bundle is wetted thereby uniformly. In fact, it is unquestionable that this configuration allows to wet sufficiently well the surface of tubes placed directly facing the spraying devices or generally the surface of the upper portion of the bundle, but it is not as effective in wetting the tube bundle portion placed therebelow. There are also solutions providing a configuration interposed between spraying devices and pipes, in a “rhombus”-like arrangement which provides each spraying device surrounded by four tubes. These solutions, if on one