US20100132927A1

US20100132927A1 - Tube-Bundle Heat Exchanger

Info

Publication number: US20100132927A1
Application number: US12/529,330
Authority: US
Inventors: Bruno Benetton; Renzo Golin
Original assignee: WTK Srl
Current assignee: WTK Srl
Priority date: 2007-07-03
Filing date: 2008-05-29
Publication date: 2010-06-03
Also published as: WO2009004422A3; WO2009004422A2; ITVI20070187A1; EP2160544A2

Abstract

The invention concerns a heat exchanger (1, 40) comprising: a first container body (2, 50); a first tube bundle (3, 57) arranged inside the first container body (2, 50); two tube plates (4, 51; 5, 52) for supporting the first tube bundle (3, 57); an evaporation chamber (2 a) defined between the first container body (2, 50), the first tube bundle (3, 57) and the tube plates (4, 51; 5, 52); an inlet head (8, 53) and an outlet head (9, 54) communicating with each other through the first tube bundle (3, 57); an inlet way (10) and an outlet way (11) for the passage of a first fluid through the heads (8, 53; 9, 54) and the first tube bundle (3, 57); an inlet mouth (12) through which a second fluid flows into the evaporation chamber (2 a). A superheating unit (20, 44) of the second fluid, associated with the first container body (2, 50), is provided.

Description

The invention concerns an improved heat exchanger with tube bundle. In particular, the heat exchanger that is the subject of the invention is of the so-called “flooded” type and is used as an evaporator in refrigerating and/or air conditioning systems.
As is known, a heat exchanger of the “flooded” type is constituted by a container body developing in a mainly longitudinal direction, in which a tube bundle is arranged.
The latter is supported at each end by a tube plate that in turn is fixed to the container body.
Each tube plate is provided with a cover that is applied thereto in such a way as to define two opposing heads, in each one of which a manifold chamber communicating with the tube bundle is defined.
The container body thus contains a heat exchange chamber delimited by the tube plates and the outer surface of the tube bundle, said chamber communicating with the outside via an inlet mouth and an outlet mouth, both created in the container body.
The heat exchange between a fluid that circulates between the manifold chambers of the heads through the tube bundle and a colder fluid that flows into the heat exchange chamber through the inlet mouth and flows out, heated, through the outlet mouth takes place in the heat exchanger.
Heat exchangers of the type described above are used as evaporators in refrigerating and/or air conditioning systems in order to evaporate the refrigerant fluid that comes from the condenser, through heat exchange with another liquid, usually water.
More precisely, the refrigerant fluid coming from the condenser is introduced in the heat exchange chamber through the inlet mouth, absorbs heat via heat exchange with the hot water that flows along the tube bundle and flows out of the outlet mouth in the form of saturated vapour.
The temperature of the water decreases during the heat exchange and when it flows out of the tube bundle the water can be used for refrigerating purposes.
Before being conveyed to the suction port of the compressor, the refrigerant fluid in the form of saturated vapour must be properly superheated in order to eliminate any liquid that is still present therein and that would damage the compressor.
In the known systems the superheating of the refrigerant fluid in the form of saturated vapour is carried out by means of superheating units with tube bundle or analogous units in which the saturated vapour to be superheated is circulated preferably countercurrent with respect to a warmer fluid, constituted for example by the same refrigerant fluid in the liquid state flowing out of the condenser.
The known systems of the type described above pose, however, some recognized drawbacks.
A first drawback lies in that the evaporator and the superheater are separated and to connect them with each other it is necessary to use pipes and fittings, which means a marked increase in the cost of the system.
Another drawback is represented by the fact that the presence of pipes and fittings for the connection between evaporator and superheater also involves increased overall dimensions and higher maintenance costs for routine inspections and checks.
A further drawback is represented by the inevitable thermodynamic losses along the pipes, which entail a reduced enthalpy difference to be exploited and therefore a lower coefficient of performance that is commonly indicated by the acronym COP.
Another, and not the least, drawback is represented by the complexity of the system when several heat exchangers must be connected in series.
The present invention aims to overcome the drawbacks listed above.
More particularly, it is a first object of the invention to construct a tube-bundle heat exchanger of the “flooded” type that is more compact and more economic to carry out than equivalent heat exchangers constructed according to the known art.
It is a further object of the invention to produce a heat exchanger that has less thermodynamic losses than the equivalent “flooded” heat exchangers of known type and therefore makes it possible to obtain higher coefficients of performance COP than those obtainable with equivalent heat exchangers of known type.
It is another, yet not the least object of the invention to produce a heat exchanger that, compared to the heat exchangers of known type, allows several heat exchangers to be connected in series more easily.
The objects described above have been achieved through the construction of a heat exchanger whose characteristics are in compliance with the main claim, to which the reader should refer for the sake of brevity.
Other details of the heat exchanger are described in the corresponding dependent claims.
According to the preferred embodiment of the invention described herein, the heat exchanger of the invention comprises:

- a first container body containing a first tube bundle;
- a superheating unit associated with the first container body and comprising
- a second container body that contains a second tube bundle.

In particular, the tube plates that support each end of the tube bundles of the heat exchanger and of the superheater are carried out in a single flange.
Advantageously, the heat exchanger that is the subject of the invention is simpler and more compact than equivalent heat exchangers constructed according to the known art.
Still advantageously, the increased compactness of the heat exchanger makes it simpler to construct than equivalent heat exchangers of known type.
Finally, to advantage, the absence of connection pipes between the heat exchanger and the superheater simplifies maintenance and also makes operation safer.

The objects and advantages described above, as well as other possible objects and advantages, will be highlighted in greater detail in the following description of a preferred embodiment of the invention, which is provided as an example without limitation, with reference to the attached drawings, wherein:

FIG. 1 shows a side view of the heat exchanger constructed according to the invention;

FIG. 2 shows the cross section of the heat exchanger shown in FIG. 1, carried out along plane II-II;

FIG. 3 shows a side view of a construction variant of the heat exchanger that is the subject of the invention;

FIG. 4 shows more heat exchangers carried out according to the variant shown in FIG. 3 and connected in series.

The heat exchanger that is the subject of the invention is represented in a longitudinal view in FIG. 1 and in cross section along plane II-II in FIG. 2, and is indicated as a whole by 1.
It can be observed that it contains a first container body 2, developing mainly in a longitudinal direction, inside which there is a first tube bundle indicated as a whole by 3, constituted by a plurality of tubes parallel to one another that substantially run along the entire length of the first container body 2.
Two tube plates 4, 5, each fixed to one end of the first container body 2, support the first tube bundle 3 at the level of its ends.
Two covers 6, 7, each applied to the outside of a corresponding tube plate 4, 5, define a head 8, 9 in which a manifold chamber 8 a, 9 a that communicates with the tube bundle 3 is defined between the plate and the to cover.
In particular it is possible to identify an inlet head 8 with corresponding inlet manifold chamber 8 a and an outlet head 9 with corresponding outlet manifold chamber 9 a that are in communication with each other through the first tube bundle 3.
An inlet way 10 created in the cover 6 and an outlet way 11 created in the cover 7 allow the flow of a first fluid through the first tube bundle 3 and the manifold chambers 8 a, 9 a, according to the direction and sense indicated by the arrow A.
Inside the first container body 2 and included between the outer surface of the first tube bundle 3 and the tube plates 4, 5, there is an evaporation chamber 2 a that is fed through an inlet mouth 12 obtained in the first container body 2 with a second fluid that flows in according to the direction and sense indicated by the arrow B.
According to the invention, the heat exchanger 1 comprises a superheating unit 20 of said second fluid, associated with said first container body 2.
Also the superheating unit 20 is of the type with tube bundle and comprises a second container body 22 that develops in a substantially longitudinal direction, inside which there is a second tube bundle 23 consisting of a plurality of tubes parallel to one another that substantially run along the entire length of the second container body 22.
Two tube plates 24, 25, each fixed to one end of the second container body 22, support the second tube bundle 23 in such a way as to define, inside the second container body 22, a superheating chamber 22 a delimited by the outer surface of the second tube bundle 23 and by the tube plates 24, 25.
Two covers 26, 27, each applied to the outside of a corresponding tube plate 24, 25, define an inlet head 28 with corresponding inlet manifold chamber 28 a and an outlet head 29 with corresponding outlet manifold chamber 29 a that are in communication with each other through the second tube bundle 23.
An inlet way 30 created in the cover 26 and an outlet way 31 created in the cover 27 allow the flow through the second tube bundle 23 according to the direction and sense indicated by the arrow C.
It is also possible to observe the presence of a plurality of intake ways 32 created in the second container body 22 for the passage of the second fluid from the evaporation chamber 2 a defined in the first container body 2 into the superheating chamber 22 a defined in the second container body 22.
Finally, in the second container body 22 there is an outlet mouth 33 for the superheated fluid, said mouth being in communication with the superheating chamber 22 a.
In particular, according to the invention, both the tube plates 4, 24; 5, 25 arranged on the same side of each tube bundle 3, 23 are obtained in a single flange 34, 35.
In practice, the heat exchanger 1 of the invention is used, for example, as evaporator-superheater in refrigerating and/or air conditioning systems comprising, among other things, at least one compressor and at least one condenser, none of which is represented herein.
The first heat exchange fluid, constituted by hot water, flows into the inlet head 8 through the inlet way 10 created in the cover 6 of the first container body 2 and then from the inlet manifold chamber 8 a it runs through the first tube bundle 3 according to the direction indicated by the arrow A until reaching the outlet head 9 and then the outlet chamber 9 a and flow out through the outlet way 11.
At the same time a second fluid, constituted for example by the hot refrigerant fluid flowing out of the condenser of the refrigerating or air conditioning system, flows through the inlet way 30 present in the cover 26 of the superheating unit 20 and runs through the second tube bundle 23 according to the direction and sense indicated by the arrow B, until reaching the outlet way 31.
The outlet way 31 communicates with the inlet mouth 12 present in the second container body 2 and thus the second fluid that flows out of the outlet way 31 enters the evaporation chamber 2 a.
The pressure inside the evaporation chamber 2 a and the temperature of the hot water that circulates in the first tube bundle 3 are such as to create the conditions necessary to allow the second fluid passing through the inlet mouth 12 to evaporate due to the heat exchange with the hot water that flows in the first tube bundle 3.
During the heat exchange, the hot water that flows in the first tube bundle 3 cools down and flows out through the outlet way 11 at a temperature that is lower than it was at the level of the inlet way 10.
Said refrigerated water can thus be reused, for example inside a cabinet or an exchange coil for refrigeration.
The second fluid that is now present in the evaporation chamber 2 a in the form of saturated vapour flows through the intake ways 32 and into the superheating, chamber 22 a, where it comes into contact with the second tube bundle 23 in which, as already said, there is the refrigerant fluid coming from the outlet of the condenser, whose temperature is higher than it was when it entered the evaporation chamber 2 a passing through the inlet mouth 12.
During the heat exchange the second hotter fluid that circulates in the second tube bundle 23 cools down and flows out through the outlet way 31 to flow back into the evaporation chamber 2 a passing through the inlet mouth 12.
At the same time, the second cooler fluid present in the superheating chamber 22 a superheats and thus when it flows out of the outlet mouth 33, it can be conveyed to the suction port of the compressor.
Substantially, therefore, during the heat exchange process the temperature of the first fluid, which in this specific case is water, at the level of the inlet way 10 of the first tube bundle 3 is higher than it is at the level of the outlet way 11 of the same first tube bundle 3, since in the evaporation chamber 2 a it transfers heat to the refrigerant fluid in the form of saturated vapour.
Therefore, using the heat exchanger of the invention as an evaporator, it is possible to superheat the refrigerant fluid that flows in through the inlet mouth 12 thanks to the heat exchange with the hot water that flows in through the inlet way 10 and flows out, cool, through the outlet way 11, and with the hot refrigerant fluid coming from the condenser that flows in through the inlet way 30 and flows out, cool, through the outlet way 31.
On the basis of the above, it is clear that the heat exchanger that is the subject of the invention achieves all the set objects.
In particular, since it is not necessary to proceed to the laying and connection of pipes and fittings for the connection of the superheating unit, the operation is more economic compared to the known art.
Furthermore, the absence of external connections between superheating unit and evaporating unit also involves reduced maintenance costs and increased coefficient of performance COP.
By means of tests carried out on prototypes, it has been found that said coefficient of performance COP, which usually ranges between 3 and 3.5 in the systems of known type, in the embodiment of the invention can even exceed 5.
Finally, construction costs result to be lower than those of equivalent heat exchangers of known type.
It is important to observe that the particular embodiment in which the tube plates 4, 24; 5, 25 arranged on both sides of the tube bundles 3, 23 belong to a single flange 34, 35 makes the heat exchanger modular.
Therefore, the same heat exchanger can be provided with superheating unit or not.
A construction variant of the heat exchanger of the invention is shown in FIG. 3, where it is indicated as a whole by 40 and differs from the variant described above owing to the different arrangement of the inlet and outlet ways, respectively 41 and 42, of the second tube bundle 43 that makes up the superheating unit 44.
It can be observed, in fact, that the inlet and outlet ways 41 and 42 communicate with the inlet and outlet heads, respectively 45 and 46, belonging to the second container body 47 that contains the second tube bundle 43 through tubular bends, respectively inlet 48 and outlet 49 bends, which project from the periphery of the first container body 50.
This embodiment is particularly useful to connect the heat exchangers in series.
By way of example, FIG. 4 shows two heat exchangers 40 that are connected in series by flanging them at the level of two adjacent tube plates 51, 52, after removal of the inlet and outlet heads 53, 54 and of the covers 55, 56 of the first tube bundle 57.
Obviously, this makes it possible to carry out a rapid connection with no need to interpose coupling sleeves, since the tubular bends 48, 49 of the inlet and outlet heads 45, 46 of the second tube bundle 43 project peripherically from the first container body 50.
On the basis of the above, it is clear that the heat exchanger that is the subject of the invention, in both the embodiments described, achieves all the set objects.
In particular, upon construction changes may be made that are not described herein or shown in the drawings.
Said construction variants must all be considered protected by the present patent, provided that they fall within the scope of the claims expressed below.
Where technical features mentioned in any claim are followed by reference signs, those reference sings have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1) Heat exchanger comprising:

a first container body that develops mainly in longitudinal direction;

a first tube bundle arranged inside said first container body;

two tube plates, each fixed to one end of said first container body in order to support said first tube bundle;

an evaporation chamber defined between said first container body, the outer surface of said first tube bundle and said tube plates;

two covers, each one of which is applied to the outside of a corresponding tube plate to define an inlet head and an outlet head communicating with each other through said first tube bundle;

at least one inlet way present in said inlet head and at least one outlet way present in said outlet head for the passage of a first fluid through said heads and said first tube bundle;

at least one inlet mouth present in said first container body for the inlet of a second fluid in said evaporation chamber;

a superheating unit of said second fluid, of the type with tube bundle and associated with said first container body,

characterized in that said superheating unit comprises:

a second container body that develops mainly in longitudinal direction;

a second tube bundle arranged inside said second container body;

two tube plates, each fixed to one end of said second container body in order to support said second tube bundle;

a superheating chamber defined between said second container body, the outer surface of said second tube bundle and said tube plates;

two covers, each one of which is applied to the outside of a corresponding tube plate to define an inlet head and an outlet head communicating with each other through said second tube bundle; at least one inlet way present in said inlet head and at least one outlet way present in said outlet head for the passage of said second fluid through said heads and said second tube bundle;

a plurality of intake ways created in said second container body for the passage of said second fluid from said evaporation chamber into said superheating chamber;

at least one outlet mouth of said superheated fluid, created in said second container body.

2) (canceled)

3) (canceled)

4) (canceled)

5) Heat exchanger according to claim 1), characterized in that each tube plate supporting said first tube bundle and each corresponding tube bundle supporting said second tube bundle are obtained in a single flange.

6) Heat exchanger according to claim 1), characterized in that in each one of said heads it is possible to identify a manifold chamber included between the cover and the corresponding tube plate, wherein said chamber communicates with a corresponding way for the passage of said first fluid and with a corresponding tube bundle.

7) Heat exchanger according to claim 1), characterized in that the temperature of said first fluid at the level of said inlet way is higher than the temperature of the same first fluid at the level of said outlet way.

8) Heat exchanger according to claim 7), characterized in that said first fluid is water.

9) Heat exchanger according to claim 1), characterized in that the temperature of said second fluid at the level of said inlet way is higher than the temperature of the same fluid at the level of said outlet way and at the level of said inlet mouth.

10) Heat exchanger according to claim 1), characterized in that said outlet way of said outlet head of said superheating unit communicates with said inlet mouth of said first container body.

11) (canceled)