EP2806244B1

EP2806244B1 - Heat exchanger distribution assembly and method

Info

Publication number: EP2806244B1
Application number: EP14169425.7A
Authority: EP
Inventors: Abbas A. Alahyari; Thomas D. Radcliff; Richard D. Rusich; Christoph E. Haugstetter
Original assignee: Hamilton Sundstrand Corp
Current assignee: Hamilton Sundstrand Corp
Priority date: 2013-05-23
Filing date: 2014-05-22
Publication date: 2019-04-24
Anticipated expiration: 2034-05-22
Also published as: US20140345837A1; EP2806244A1

Description

BACKGROUND OF THE INVENTION

The present invention relates to heat exchanger arrangements, and more particularly to a heat exchanger distribution assembly, as well as a method of distributing fluid to a heat exchanger.
Distribution of two-phase fluid flow (liquid and gas) inside heat exchangers poses several challenging issues. In heat exchangers, such as mini-channel, micro-channel, plate-fin, and brazed-plate heat exchangers, for example, distribution is particularly difficult due to the requirement that the flow must be distributed among many layers and small ports. To overcome the challenges, these types of heat exchangers may employ a piccolo distributor having a closed-end tube with a series of holes in the side. The assumption behind this approach is that the flow entering the distributor is annular or well-mixed and remains that way through the distributor tube. However, the cavity within the distributor may not be able to avert separation of the two-phase fluid under different operating conditions. The flow may tend to stratify due to deceleration in the distributor and as a result, liquid pools at the end of the tube while vapor leaves through early ports. Therefore, the mass fraction provided to each fin passage is not properly apportioned and may yield poor system performance.
A heat exchanger distribution assembly with the features of the preamble to claim 1 and a related method of distributing fluid to layers of a heat exchanger is disclosed in US 4,513,587 . Another heat exchanger distribution assembly and a method of distributing fluid to layers of a heat exchanger is disclosed in DE 3150187 .

BRIEF DESCRIPTION OF THE INVENTION

From one aspect, the present invention provides a heat exchanger distribution assembly in accordance with claim 1.
From another aspect, the present invention provides a method of distributing fluid to layers of a heat exchanger in accordance with claim 11.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional view of a heat exchanger arrangement which falls outside the scope of the present invention;
FIG. 2 is a perspective view of a heat exchanger distribution assembly of the heat exchanger arrangement which falls outside the scope of the present invention;
FIG. 3 is a cross-sectional view of the heat exchanger distribution assembly according to FIG. 2;
FIG. 4 is a perspective view of the heat exchanger distribution assembly according to an embodiment of the invention;
FIG. 5 is a disassembled view of the heat exchanger distribution assembly according to the embodiment of FIG. 4;
FIG. 6 is a cross-sectional view of the heat exchanger distribution assembly according to another aspect of the above arrangements and embodiment;
FIG. 7 is a disassembled view of a heat exchanger distribution assembly; and
FIG. 8 is a flow diagram illustrating a method of distributing fluid to layers of a heat exchanger.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a heat exchanger arrangement 10 is schematically illustrated. The heat exchanger arrangement 10 may be used in conjunction with an assembly or system of a vehicle, such as an aircraft, however, it is contemplated that other vehicles or applications may benefit from the embodiments described herein. In certain embodiments, the heat exchanger arrangement 10 is employed in an aircraft air conditioning system or refrigeration unit. The heat exchanger arrangement 10 includes an expansion valve assembly 12 configured to reduce pressure from a refrigerant to allow expansion or change of state from a liquid to a vapor, thereby resulting in a fluid 14 comprising a two-phase flow. The fluid 14 is supplied to a heat exchanger distribution assembly 16. As shown, the heat exchanger distribution assembly 16 is illustrated in an installed condition with the expansion valve assembly 12 and a heat exchanger 18, such as an evaporator. It is contemplated that the embodiments of the heat exchanger distribution assembly 16 may be used in conjunction with various types of heat exchangers, such as those having a construction referred to as micro-channel, mini-channel, plate-fin, and brazed plate.
Referring to FIG. 7, a heat exchanger distribution assembly 16 is illustrated. The distribution assembly 16 includes an outer shell 20 that includes an outer surface 22 and an inner surface 24, with the inner surface 24 defining a hollow portion 26. A channel guide 28 is disposed within the hollow portion 26 and includes an outer surface 30. The general geometry of the channel guide 28 substantially corresponds to the inner surface 24 of the outer shell 20. The hollow portion 26 and the channel guide 28 are formed in a substantially cylindrical manner, however, cross-sectional geometries having a non-circular geometry are contemplated.
Referring to FIGS. 2 and 3, which show an arrangement which falls outside the sope of the invention, the outer shell 20 is operatively coupled to the heat exchanger 18 and to the expansion valve assembly 12 proximate a first end 27 of the outer shell 20. Coupling with the expansion valve assembly 12 forms a fluid inlet path 32 that facilitates fluid communication between the expansion valve assembly 12 and a homogenized fluid supply arrangement. In one arrangement, the homogenized fluid supply arrangement comprises a nozzle 34, but it is to be appreciated that alternative suitable arrangements may be employed to provide a homogenized flow. The illustrated arrangement includes additional components, with respect to the outer shell 20 and the channel guide 28. The nozzle 34 is located within a hollowed region of the channel guide 28 and includes an orifice 36 that restricts the cross-sectional area of the fluid inlet path 32 and is configured to increase the velocity of the fluid 14 flowing from the expansion valve assembly 12. Increasing the velocity of the fluid 14 advantageously provides a substantially uniform, homogeneous mixture of the fluid 14. In one arrangement, the orifice 36 of the nozzle 34 comprises a venturi path portion 37 to reduce the pressure drop of the fluid 14 passing therethrough. The illustrated nozzle 34 is shown in what is referred to herein as a horizontal alignment, however, alternative angles are contemplated.
Disposed downstream of, and adjacent to, the nozzle 34 is a diffuser 38 that may be a portion of the channel guide 28 or a separate component. Regardless, the diffuser 38 comprises a plurality of circumferentially spaced distribution tubes 40 in fluid communication with the nozzle 34. In particular, each of the plurality of distribution tubes 40 are configured to receive the fluid 14 upon passing through the orifice 36 of the nozzle 34, thereby separating the fluid equally into a plurality of fluid routing paths 42. It is contemplated that the nozzle 34 and the diffuser 38 are integrally formed in one arrangement.
The plurality of distribution tubes 40 route the fluid 14 to a location proximate a second end 44 of the outer shell 20 and transition the fluid 14 at a transition point 43 to a plurality of channel grooves 46 disposed between the inner surface 24 of the outer shell 20 and the outer surface 30 of the channel guide 28. The channel grooves 46 may be formed in either, or both, of the inner surface 24 of the outer shell 20 and the outer surface 30 of the channel guide 28. In an arrangement comprising channel grooves formed in only the inner surface 24 of the outer shell 20, the channel guide 28 comprises a substantially smooth outer surface. Conversely, in an arrangement comprising channel grooves formed in only the outer surface 30 of the channel guide 28, the inner surface 24 of the outer shell 20 comprises a substantially smooth inner surface. In either arrangement, the smooth surface substantially seals the plurality of channel grooves 46 to provide a continuation of the plurality of fluid routing paths 42. The plurality of channel grooves 46 may include varying lengths and/or hydraulic diameters to equalize pressure drop through the different paths in order to equalize flow, if necessary.
The outer shell 20 includes a plurality of distribution holes 48 extending radially therethrough from the outer surface 22 to the inner surface 24 of the outer shell 20. The plurality of distribution holes 48 are aligned with desired inlet locations of the heat exchanger 18. Specifically, each of the plurality of distribution holes 48 are aligned with a corresponding layer 50 (FIG. 1) of the heat exchanger 18. In the illustrated arrangement, the plurality of distribution holes 48 are coaxially aligned in a single axis, but it is to be appreciated that the plurality of distribution holes 48 may be circumferentially angled from each other. Each of the plurality of channel grooves 46 lead to a corresponding distribution hole 48, such that a homogeneous mixture of the fluid 14 is maintained and routed to each layer 50 of the heat exchanger 18. As an alternative to a single channel groove leading to a single distribution hole, each channel groove 46 leads to a group of distribution holes (FIG. 6). It is to be appreciated that the channel grooves 46 may be configured to route the fluid 14 to the distribution holes 48 in numerous routing paths. For example, a straight or helical path may be taken by the fluid 14 during routing to the distribution holes 48.
Referring to FIGS. 4 and 5, a heat exchanger distribution assembly 100 according to an embodiment of the invention is illustrated. The embodiment is similar in many respects to the arrangements described in detail above, such that duplicative description of each component, as well as each component's functionality, is not necessary and similar reference numerals are employed where applicable.
In the embodiment, the nozzle 34 and the diffuser 38 are located externally relative to the channel guide 28 and the hollow portion 26 of the outer shell 20. Specifically, the nozzle 34 is disposed adjacent to, or at least partially within, the diffuser 38 to route the fluid 14 to the plurality of distribution tubes 40. Sandwiched between the diffuser 38 and the channel guide 28 is an orifice ring 102 that includes a plurality of circumferentially spaced holes 104 to ensure precision control of flow apportionment from each of the plurality of distribution tubes 40 to account for small differences in frictional losses due to the different lengths of each of the plurality of channel grooves 46. In one embodiment, the orifice ring 102 is integrally formed with the channel guide 28.
The embodiment may include channel grooves 46 that route the fluid 14 to more than one distribution hole 48, as described in the arrangements detailed above. The nozzle 34 and/or the diffuser 38 may be oriented substantially vertically and the channel guide 28 may include a bend of numerous angles.
In operation, the embodiment described above advantageously increases the velocity of the fluid 14 with the nozzle 34 and route the fluid 14 along individual fluid routing paths 42 to the plurality of distribution holes 48 for provision to the layers 48 of the heat exchanger 18.
A method of distributing fluid to layers of a heat exchanger 200 is also provided, as illustrated in FIG. 7 and with reference to FIGS. 1-6. The heat exchanger distribution assembly 16 has been previously described and specific structural components need not be described in further detail. The method of distributing fluid to layers of a heat exchanger 200 includes supplying the fluid to a plurality of distribution tubes of a diffuser to separate the fluid into a plurality of fluid routing paths 202. The fluid is apportioned through a plurality of circumferentially spaced holes of an orifice ring 204. The fluid is routed through a plurality of channel grooves disposed between and outer surface of a channel guide and an inner surface of an outer shell 206. The fluid is distributed to a plurality of layers of the heat exchanger through a plurality of distribution holes aligned with the plurality of channel grooves 208.
While the invention has been described in detail in connection with only a single embodiment, it should be readily understood that the invention is not limited to such disclosed embodiment. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the scope of the invention. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

A heat exchanger distribution assembly (16) comprising:
a channel guide (28) comprising an outer surface (30);

an outer shell (20) comprising a hollow portion (26) and a plurality of distribution holes (48), wherein the channel guide (28) is at least partially disposed within the hollow portion (26);

a plurality of channel grooves (46) disposed between an inner surface (24) of the outer shell (20) and the outer surface (30) of the channel guide (28), wherein the plurality of channel grooves (46) are configured to convert circumferentially spaced flow passages to axially spaced flow passages to route the fluid to a plurality of layers (50) of a heat exchanger (18); and

a nozzle (34) configured to provide a homogenized fluid to a diffuser (38) having a plurality of distribution tubes (40), wherein the plurality of distribution tubes (40) are configured to separate the fluid into a plurality of fluid routing paths (42); characterised by

further comprising an orifice ring (102) having a plurality of circumferentially spaced holes (104) aligned with the plurality of distribution tubes (40), wherein the nozzle (34) and the diffuser (38) are located externally relative to the channel guide (28) and the hollow portion (26) of the outer shell (20).
The heat exchanger distribution assembly of claim 1, wherein the orifice ring (102) is integrally formed with the channel guide (28).
The heat exchanger distribution assembly of claim 1 or 2, wherein the nozzle (34) is integrally formed with the diffuser (38).
The heat exchanger distribution assembly of any of claims 1, 2 or 3, wherein the plurality of fluid routing paths (42) of the diffuser (38) route the fluid to the plurality of channel grooves (46) at a transition point (43) proximate an end of the channel guide (28).
The heat exchanger distribution assembly of any preceding claim, wherein the nozzle (34) comprises a venturi path portion (37).
The heat exchanger distribution assembly of any preceding claim, wherein the plurality of channel grooves (46) are formed within the outer surface (30) of the channel guide (28).
The heat exchanger distribution assembly of any preceding claim, wherein the plurality of channel grooves (46) are formed within the inner surface (24) of the outer shell (20).
The heat exchanger distribution assembly of any preceding claim, wherein each of the plurality of channel grooves (46) route the fluid to a single corresponding distribution hole (48).
The heat exchanger distribution assembly of any of claims 1 to 7, wherein each of the plurality of channel grooves (46) route the fluid to more than one distribution hole (48).
The heat exchanger distribution assembly of any preceding claim, wherein at least one of the plurality of distribution holes (48) is circumferentially spaced from another distribution hole (48).
A method of distributing fluid to layers (50) of a heat exchanger (18) comprising:
supplying a fluid to a plurality of distribution tubes (40) of a diffuser (38) to separate the fluid into a plurality of fluid routing paths (42);

apportioning the fluid through a plurality of circumferentially spaced holes (104) of an orifice ring (102);

routing the fluid through a plurality of channel grooves (46) disposed between an outer surface (30) of a channel guide (28) and an inner surface (24) of an outer shell (20); and

distributing the fluid to a plurality of layers (50) of the heat exchanger (18) through a plurality of distribution holes (48) aligned with the plurality of channel grooves (46), wherein a nozzle (34) is configured to supply the fluid to the diffuser (38) and the nozzle (34) and the diffuser (38) are located externally relative to the channel guide (28) and the hollow portion (26) of the outer shell (20).
The method of claim 11, wherein each of the plurality of channel grooves (46) route the fluid to a single, corresponding distribution hole (48).
The method of claim 11 or 12, wherein the diffuser (38) is located at an internal location of the outer shell (20), the method further comprising transitioning the fluid from the plurality of fluid routing paths (42) to the plurality of channel grooves (46) at a location proximate an end of the channel guide (28).