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EP-4739970-A1 - TUBE BUNDLE HEAT EXCHANGER WITH MULTI-LEVEL SPRAYING SYSTEM

EP4739970A1EP 4739970 A1EP4739970 A1EP 4739970A1EP-4739970-A1

Abstract

The present invention relates to a heat exchanger configured with a distribution device of the cooling fluid at several vertical levels into a tube bundle suitably organized in groups of tubes insisting on such vertical levels.

Inventors

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

Assignees

  • Wieland Provides Srl

Dates

Publication Date
20260513
Application Date
20240625

Claims (19)

  1. 1. A heat exchanger suitable to be used as evaporator, comprising: a plurality of parallel tubes (T) arranged substantially horizontally, the tubes having an outer surface, a distribution device (4’) to distribute a cooling fluid on the outer surface of said tubes, the distribution device comprising at least one of means (41’n) for spraying said fluid placed at a respective vertical level of spraying (nVL), wherein such respective vertical level is placed into the plurality of tubes (T) by dividing it into two groups of tubes, a lower group (1 ’inf) situated at a lower vertical level than said respective vertical spraying level and an upper group (1’sup) placed at a higher vertical level than said respective vertical spraying level, wherein said lower group of tubes and said upper group of tubes comprise, each one, at least two horizontal rows of tubes.
  2. 2. The heat exchanger according to claim 1 , wherein said lower group (1’inf) and said upper group of tubes (1’sup) are vertically spaced apart by defining a gap (Gn).
  3. 3. The heat exchanger according to claim 2, wherein said at least one of the spraying means is arranged to spray the fluid on said second group of tubes and/or on said lower group of tubes through said gap (Gn).
  4. 4. The heat exchanger according to claim 1 , 2 or 3, wherein said distribution device (4’) comprises at least a first conduit (43’) extending at least partially into the plurality of tubes (T) and said at least one of the spraying means is arranged on said at least a first conduit (43’).
  5. 5. The heat exchanger according to claim 4, wherein said at least a first conduit (43’) extends substantially vertically.
  6. 6. The heat exchanger according to claim 5, wherein said distribution device comprises a second conduit (40’) extending substantially horizontally and parallelly to the tubes of said plurality.
  7. 7. The heat exchanger according to claim 6, wherein from said second conduit (40’) two or more of said first conduits (43’) extend.
  8. 8. The heat exchanger according to claim 7, wherein each one of said first conduits (43’) comprises at least one (41’n) of said spraying means arranged at its own respective vertical spraying level.
  9. 9. The heat exchanger according to any one of claims 3 to 8, wherein said distribution device comprises at least a first one (41 T) of spraying means arranged at a first vertical spraying level (1VL) and at least a second one (412’) of spraying means, arranged at a second vertical spraying level (2VL) wherein said second vertical spraying level is arranged above the first one.
  10. 10. The heat exchanger according to claim 9, wherein a first group of tubes (1’a) is defined lower than said first vertical spraying level (1VL), a second group of tubes (1’b) is placed above said first vertical spraying level (1VL) and said first and second group of tubes are spaced apart vertically to define a first gap (G1 ) through which said at least one (41 T) of first spraying means sprays.
  11. 11. The heat exchanger according to claim 10, wherein a third group of tubes (1’c) is placed above said second vertical spraying level (2VL), said third group of tubes being spaced vertically with respect to said second group of tubes (1’b) by defining a second gap (G2) through which said at least one (412’) of second spraying means sprays.
  12. 12. The heat exchanger according to claim 9, 10 or 11 , wherein said at least one of first spraying means and at least one of second spraying means are arranged on a same first conduit (43’) of said distribution device.
  13. 13. The heat exchanger according to any one of claims 9 to 12, further comprising at least one (413’) of third spraying means, arranged at a third vertical level (3VL) above said second vertical spraying level.
  14. 14. The heat exchanger according to claim 13, wherein said at least one of third spraying means, said at least one of second spraying means and said at least one of first spraying means are arranged on a same first conduit of said distribution device.
  15. 15. The heat exchanger according to claim 14, wherein a fourth group of tubes (1’d) is arranged above said third vertical level and it is spaced vertically from the third group of tubes to define a third gap (G3) through which said at least one of third spraying means sprays.
  16. 16. The heat exchanger according to any one of claims 9 to 15, wherein said first group of tubes (1’a) is arranged at a base region (B) of said exchanger and at least partially immersed into said cooling fluid.
  17. 17. The heat exchanger according to claim 16, wherein said at least one of first spraying means is configured to spray fluid through said first gap (G1 ) mainly on said second group of tubes (1’b) placed above said first vertical spraying level.
  18. 18. The heat exchanger according to any one of the preceding claims, wherein additional spraying means is provided placed directly on said second horizontal conduit (40’) or at an upper end of said first conduit to spray said plurality of tubes with a fluid spraying from top.
  19. 19. The heat exchanger according to any one of the preceding claims, wherein each one of said spraying means is a nozzle.

Description

TUBE BUNDLE HEAT EXCHANGER WITH MULTI-LEVEL SPRAYING SYSTEM 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, which implements a multi-level system for spraying the cooling fluid flow on the tube bundle. 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 devic