Heat exchangers with flow distributing orifice partitions

Information

  • Patent Grant
  • 6698509
  • Patent Number
    6,698,509
  • Date Filed
    Tuesday, October 9, 2001
    23 years ago
  • Date Issued
    Tuesday, March 2, 2004
    20 years ago
Abstract
A heat exchanger which is particularly useful as an evaporator has a first plurality of stacked plate pairs with cooling fins therebetween. A second plurality of stacked plate pairs is located adjacent to the first. Each plurality of plate pairs has enlarged plate end portions which together define flow manifolds. The first plate pairs have a first inlet manifold and a first outlet manifold. The second plate pairs have a second inlet manifold and second outlet manifold. The first outlet manifold is joined to communicate with the second outlet manifold. The second inlet manifold is joined to communicate with the first inlet manifold, but a barrier is located between the first and second inlet manifolds. The barrier has an orifice to permit a portion only of the flow in the first inlet manifold to pass into the second inlet manifold to produce a more uniform flow distribution inside the heat exchanger.
Description




BACKGROUND OF THE INVENTION




This invention relates to heat exchangers, and in particular, to heat exchangers involving gas/liquid, two-phase flow, such as in evaporators or condensers.




In heat exchangers involving two-phase, gas/liquid fluids, flow distribution inside the heat exchanger is a major problem when the two-phase flow passes through multiple channels which are all connected to common inlet and outlet manifolds, the gas and liquid have a tendency to flow through different channels at different rates due to the differential momentum and the changes in flow direction inside the heat exchanger. This causes uneven flow distribution for both the gas and the liquid, and this in turn directly affects the heat transfer performance, especially in the area close to the outlet where the liquid mass proportion is usually quite low. Any maldistribution of the liquid results in dry-out zones or hot zones. Also, if the liquid-rich areas or channels cannot evaporate all of the liquid, some of the liquid can exit from the heat exchanger. This often has deleterious effects on the system in which the heat exchanger is used. For example, in a refrigerant evaporator system, liquid exiting from the evaporator causes the flow control or expansion valve to close reducing the refrigerant mass flow. This reduces the total heat transfer of the evaporator.




In conventional designs for evaporators and condensers, the two-phase flow enters the inlet manifold in a direction usually perpendicular to the main heat transfer channels. Because the gas has much lower momentum, it is easier for it to change direction and pass through the first few channels, but the liquid tends to keep travelling to the end of the manifold due to its higher momentum. As a result, the last few channels usually have much higher liquid flow rates and lower gas flow rates than the first one. Several methods have been tried in the past to even out the flow distribution in evaporators. One of these is the use of an apertured inlet manifold as shown in U.S. Pat. No. 3,976,128 issued to Patel et al. Another approach is to divide the evaporator up into zones or smaller groupings of the flow channels connected together in series, such as is shown in U.S. Pat. No. 4,274,482 issued to Noriaki Sonoda. While these approaches tend to help a bit, the flow distribution is still not ideal and inefficient hot zones still result.




SUMMARY OF THE INVENTION




In the present invention, barriers or partitions are used in the inlet manifold to divide the heat exchanger into sections. The barriers have orifices to allow a predetermined proportion of the flow to pass through to subsequent sections, so that the flow in the sequential sections is maintained in parallel and more evenly distributed.




According to the invention, there is provided a heat exchanger comprising a first plurality of stacked, tube-like members having respective inlet and outlet distal end portions defining respective of inlet and outlet openings. All of the inlet openings are joined together so that the inlet distal end portions form a first inlet manifold, and all of the outlet openings are joined together so that the outlet distal end portions form a first outlet manifold. A second plurality of stacked, tube-like members is located adjacent to the first plurality of tube-like members. The second plurality of tube-like members also has inlet and outlet distal end portions defining respective inlet and outlet openings. All of the inlet openings are joined together so that the inlet distal end portions form a second inlet manifold and all of the outlet openings are joined together so that the outlet distal end portions form a second outlet manifolds. The second outlet manifold is joined to communicate with the first outlet manifold. The second inlet manifold is joined to communicate with the first inlet manifold. A barrier is located between the first and second inlet manifolds. The barrier defines an orifice to permit the portion only of the flow in the first inlet manifold to pass into the second inlet manifold.











BRIEF DESCRIPTION OF THE DRAWINGS




Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:





FIG. 1

is an elevational view of a preferred embodiment of a heat exchanger according to the present invention;





FIG. 2

is a top or plan view of the heat exchanger shown in

FIG. 1

;





FIG. 3

is a left end view of the heat exchanger shown in

FIG. 1

;





FIG. 4

is an enlarged elevational view of one of the main core plates used to make the heat exchanger of

FIG. 1

;





FIG. 5

is a left side or edge view of the plate shown in

FIG. 4

;





FIG. 6

is an enlarged sectional view taken along lines


6





6


of

FIG. 4

;





FIG. 7

is a plan view of one type of barrier or partition shim plate used in the heat exchanger shown in

FIGS. 1

to


3


;





FIG. 8

is an enlarged sectional view taken along lines


8





8


of

FIG. 7

;





FIG. 9

is a left end view of the barrier plate shown in

FIG. 7

;





FIG. 10

is a front or elevational view of the barrier plate shown in

FIG. 7

;





FIG. 11

is a plan view, similar to

FIG. 7

, but showing another type of barrier or partition plate used in the heat exchanger of

FIGS. 1

to


3


;





FIG. 12

is plan view, similar to

FIGS. 7 and 11

, but showing yet another type of barrier or partition plate used in the heat exchanger of

FIGS. 1

to


3


;





FIG. 13

is an elevational view, similar to

FIG. 4

, but showing another type of core plate used in the heat exchanger of

FIGS. 1

to


3


;





FIG. 14

is an elevational view similar to

FIGS. 4 and 13

, but showing yet another type of core plate used in the heat exchanger of

FIGS. 1

to


3


;





FIG. 15

is an enlarged sectional view taken along lines


15





15


of

FIG. 14

;





FIG. 16

is an elevational view similar to

FIGS. 4

,


13


and


14


, but showing yet another type of core plate used in the heat exchanger of

FIGS. 1

to


3


;





FIG. 17

is an enlarged scrap view of the area indicated by circle


5


in

FIG. 16

, but showing a modification to the location of the orifice;





FIG. 18

is a scrap view similar to

FIG. 17

but showing yet another modification to the flow orifice;





FIG. 19

is a scrap view similar to

FIGS. 17 and 18

but showing yet another modification to the flow orifice;





FIG. 20

is a scrap view similar to

FIGS. 17

to


19


but showing yet another modification to the flow orifice;





FIG. 21

is a diagrammatic perspective view taken from the front and from the right side showing the flow path inside the heat exchanger of

FIGS. 1

to


3


;





FIG. 22

is a perspective view similar to

FIG. 21

, but taken from the rear and from the left side of the heat exchanger of

FIGS. 1

to


3


;





FIG. 23

is a perspective view similar to

FIGS. 21 and 22

, but illustrating the flow path in another preferred embodiment of the present invention;





FIG. 24

is a scrap view similar to

FIG. 17

, but showing a portion of one of the core plates that is used in the embodiment of

FIG. 23

;





FIG. 25

is a scrap view similar to

FIG. 24

but showing a modified type of orifice;





FIG. 26

is a scrap view similar to

FIGS. 24 and 25

, but showing yet another modification to the orifice;





FIG. 27

is a scrap view similar to

FIGS. 24

to


26


, but showing yet another modification to the orifice; and





FIG. 28

is an elevational view of a core plate that is used in another preferred embodiment of the invention where the inlet and outlet manifolds are located at opposed ends of the core plate, rather than being adjacent as in the embodiments shown in

FIGS. 1

to


3


.











DESCRIPTION OF THE PREFERRED EMBODIMENT




Referring firstly to

FIGS. 1

to


6


, a preferred embodiment of the present invention is made up of a plurality of plate pairs


20


formed of back-to-back plates


14


of the type shown in

FIGS. 4

to


6


. These are stacked, tube-like members having enlarged distal end portions or bosses


22


,


26


having inlet


24


and outlet


30


openings, so that the flow travels in a U-shaped path through the plate pairs


20


. Each plate


14


preferably includes a plurality of evenly spaced dimples


6


projecting into the flow channel created by each plate pair


20


. Preferably, fins


8


are located between adjacent plate pairs. The bosses


22


on one side of the plate are joined together to form an inlet manifold


32


and the bosses


26


on the other side of the plates are joined together to form an outlet manifold


34


. As seen best in

FIG. 2

, a longitudinal tube


15


passes into the inlet manifold openings


24


in the plates to deliver the incoming fluid, such as a two-phase, gas/liquid mixture of refrigerant, to the right hand section of the heat exchanger


10


.

FIG. 3

shows end plate


35


with an end fitting


37


having openings


39


,


41


in communication with the inlet manifold


32


and outlet manifold


34


, respectively.




The heat exchanger


10


is divided into plate pair sections A, B, C, D, E by placing barrier or partition plates


7


,


11


,


12


, such as are shown in

FIGS. 7

to


12


, between selected plate pairs in the heat exchanger. The inlet and outlet manifolds formed in the plate pairs of each section may be considered separate manifolds from each other, the inlet manifolds of adjacent sections being joined to communicate with one another and the outlet manifolds of adjacent sections being joined to communicate with one another. For example the inlet manifold


32


of section C is joined to communicate with the inlet manifold of section D and the outlet manifold of section C is joined to communicate with the outlet manifold of section D. Referring to

FIGS. 21 and 22

, sections are shown schematically, and the dividing walls represent actual barrier plates


7


,


11


, and


12


as shown in

FIGS. 7

,


11


and


12


. As shown in

FIGS. 7

to


12


, each barrier may have an end flange or flanges


42


positioned such that the barrier plates can be distinguished from one another when positioned in the heat exchanger. For example barrier plate


7


has two end flanges


42


, barrier plate


11


has a lower positioned end flange


42


and barrier plate


12


has an upper positioned end flange


42


. The direction of flow is indicated with arrows. Referring again to

FIGS. 21 and 22

, an inlet tube


15


delivers the fluid through an inlet


18


to the right hand section A of the heat exchanger where it would travel down along the back, or along the right hand side of the plates


14


as seen in

FIG. 4

, cross over and travel up the front, or along the left hand side of the plates as seen in FIG.


4


. Barrier plates


7


,


12


each include an opening


70


to accommodate the inlet tube


15


. The flow then passes through a left hand hole


36


of barrier


7


, traveling down along the font of the next section B of plates, across and up the back of these plates to pass through a hole


38


in barrier plate


11


(see

FIG. 11

) which surrounds tube


15


.




Most of the flow then travels down the backside add up the front of the next section C of the heat exchanger plates and passes out via the outlet manifold through an outlet hole


40


, which is the left hand hole of the barrier plate


12


shown in FIG.


12


through to the outlet manifold of section D. However, some of the flow passes via the inlet manifold of section C through a small orifice


17


(see

FIG. 12

) and into the inlet manifold of the next section D of core plates. In this next section D, flow again travels down the back and up the front and out through the outlet hole


40


in the next barrier


12


. Again some of the flow goes through the inlet manifold through an orifice


17


into the inlet manifold of yet another section E of core plates. In this last section E of core plates, the flow goes down the back, up the front and finally out of the heat exchanger outlet


58


.




Referring again to

FIG. 21

, it will be appreciated that in the first two sections of core plates from the right A, B the fluid is flowing in series through these sections. However, when the fluid reaches the third section C, most of it travels in the U-shaped direction, but some of it is passed via the inlet manifold through the small orifices


17


in plates


12


, to the next section's inlet manifold so that the flow in the last three sections of core plates is in parallel. This parallel flow produces proportional, even flow distribution to balance the flow rate among all of the sections in the heat exchanger.




Rather than using the core plates of FIG.


4


and the barrier or partition plates of

FIGS. 7

to


12


, the partitions of

FIGS. 7

to


12


could actually be built right in or made an integral part of the core plates


50


,


52


,


54


as shown in

FIGS. 13

to


16


. Core plate


50


as shown in

FIG. 13

is equivalent to core plate


14


of

FIG. 4

with a barrier plate


7


of

FIG. 7

in that it has outlet opening


30


but inlet opening


24


includes an integral barrier


60


with a hole


70


therethrough to accomodate tube


15


. Core plate


52


of

FIG. 14

is equivalent to core plate


14


of

FIG. 4

with a barrier plate


11


of

FIG. 11

in that outlet opening


30


is blocked by an integral barrier


62


and inlet opening


24


is not blocked. Core plate


54


of

FIG. 16

is equivalent to core plate


14


of

FIG. 4

with a barrier or partition plate


12


of

FIG. 12

in that inlet opening


24


is blocked by an integral barrier


64


having a hole


70


to accommodate tube


15


and an orifice


17


thereby allowing a portion of flow to pass through the inlet manifold to the next section. It will be appreciated that the core plates of FIG.


13


and

FIG. 14

would be used in the

FIG. 21

embodiment in the location of the respective partitions


7


and


11


. The core plate shown in

FIG. 16

would be used where the partitions


12


are indicated in FIG.


21


.





FIGS. 17

to


20


show different configurations of orifices


17


in core plates that would be used in the location of barriers


12


in the embodiment of FIG.


21


. The different orifices


17


are used to balance the flow rates amongst all of the sections in the manifold. The flow rates can be controlled by adjusting the sizes or locations (top or bottom) or the shapes of the orifices, such as round, vertical slot, horizontal slot or any other configuration. The location of the orifice high or low on the partition or core plate can be used to adjust the proportion of liquid to gas phase within the flow that is passed through the orifice, while the size of the hole is used more to adjust the overall mass flow rate. The sensitivities of the orifice size and location will tend to be application-specific, depending on how well mixed the two phases of the flow are at the point of flow splitting. Also, rather than one orifice hole, several smaller holes would be used. Further, the orifice in the first partition plate could be larger, or there could be more orifices, than in the second or down stream partition or barrier (see FIGS.


21


and


22


).




In the embodiment represented by

FIG. 23

, it will be noted that there is no longitudinal inlet tube. The flow as indicated with arrows enters the left side of the heat exchanger, travels in series through the first two sections, and then in parallel through the last three sections in a manner similar to that of the embodiment of

FIGS. 21 and 22

. In this

FIG. 23

embodiment, it will also be noted that the inlet


18


and outlet


58


are at opposite ends of the heat exchanger, rather than being adjacent as in the embodiment of

FIGS. 21 and 22

. In the embodiment of

FIG. 23

, the core plates would not have holes to accommodate a longitudinal inlet tube, as indicated in

FIGS. 24

to


27


. Similar modifications will be made to the barrier or partition plates


7


,


11


,


12


of

FIGS. 7 and 12

, if such barriers are used with the core plates


14


of

FIG. 4

to make a heat exchanger as indicated in FIG.


23


.




As mentioned above, the flow through the core plates travels in a U-shaped path in the embodiments of

FIGS. 1

to


27


. However, this U-shaped path could be, in effect, straightened out, in which case core plates


56


as shown in

FIG. 28

would be used.




As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. The foregoing description is of the preferred embodiments and is by way of example only, and is not to limit the scope of the invention.



Claims
  • 1. A heat exchanger comprising:a first plurality (C) of stacked, tube-like members having respective first inlet and first outlet distal end portions defining respective first inlet and first outlet openings, all of said first inlet openings being joined together so that the first inlet distal end portions form a first inlet manifold and all of said first outlet openings being joined together so that the first outlet distal end portions form a first outlet manifold; a second plurality (D) of stacked, tube-like members located adjacent to said first plurality of tube-like members, the second plurality of tube-like members having second inlet and second outlet distal end portions defining respective second inlet and second outlet openings, all of said second inlet openings being joined together so that the second inlet distal end portions form a second inlet manifold and all of said second outlet openings being joined together so that the second outlet distal end portions form a second outlet manifold; a third plurality (E) of stacked, tube-like members located adjacent to said second plurality (D) of tube-like members, the third plurality of tube-like members having third inlet and third outlet distal end portions defining respective third inlet and third outlet openings, all of said third inlet openings being joined together so that the third inlet distal end portions form a third inlet manifold and all of said third outlet openings being joined together so that the third outlet distal end portions form a third outlet manifold; the second outlet manifold being joined to communicate with the first outlet manifold; the second inlet manifold being joined to communicate with the first inlet manifold; a first barrier located between the first and second inlet manifolds, the first barrier defining a first orifice to permit a portion only of the flow in the first inlet manifold to pass into the second inlet manifold; the third outlet manifold being joined to communicate with the second outlet manifold; the third inlet manifold being joined to communicate with the second inlet manifold; a second barrier located between the second and third inlet manifolds, the second barrier defining a second orifice to permit a portion only of the flow in the second inlet manifold to pass into the third inlet manifold, said first orifice and said second orifice having different configurations; and a fluid inlet tube for the heat exchanger that passes through the first, second and third inlet manifolds and through openings provided through the first and second barriers, the openings being discrete from the orifices.
  • 2. A heat exchanger according to claim 1 wherein the first and second barriers engage the fluid inlet tube about circumferences of the respective openings therethrough.
  • 3. A heat exchanger as claimed in claim 1 wherein the size of the first orifice is larger than the size of the second orifice.
  • 4. A heat exchanger as claimed in claim 1 wherein a greater number of orifices are provided through the first barrier than through the second barrier.
  • 5. A heat exchanger as claimed in claim 1 wherein at least one of the effective size, relative location, and shape of the first orifice is different than that of the second orifice.
  • 6. A heat exchanger as claimed in claim 1 wherein at least one of the first barrier and the second barrier has a plurality of the orifices formed therethrough, the collective effective size of all orifices through the first barrier being larger than that of all orifices through the second barrier.
  • 7. A heat exchanger as claimed in claim 1 wherein the shape of the second orifice is different than that of the first orifice.
  • 8. A heat exchanger as claimed in claim 1 wherein a relative location of the first orifice on the first barrier is different from that of the second orifice on the second barrier.
  • 9. A heat exchanger according to claim 2 wherein the first and second barriers are discrete baffle plate inserts.
  • 10. A heat exchanger according to claim 1 wherein the first barrier is integrally formed in one of the adjacent portions of the first and second inlet manifolds and the second barrier is integrally formed in one of the adjacent end portions of the second and third inlet manifolds.
  • 11. A heat exchanger as claimed in claim 1 wherein said portion of the flow passing through the first orifice is small enough that it does not materially affect the flow velocity through the first plurality of stacked tube-like members.
  • 12. A heat exchanger as claimed in claim 1 wherein at least one of orifices is a horizontal slot.
  • 13. A heat exchanger as claimed in claim 1 wherein at least one of said orifices is a vertical slot.
  • 14. A heat exchanger as claimed in claim 1 wherein each said tube-like member is a plate pair formed of back-to-back plates defining a flow channel therebetween.
Priority Claims (1)
Number Date Country Kind
2323026 Oct 2000 CA
US Referenced Citations (9)
Number Name Date Kind
3976128 Patel et al. Aug 1976 A
4274482 Sonoda Jun 1981 A
4936381 Alley Jun 1990 A
4945635 Nobusue Aug 1990 A
5025855 Hoshino et al. Jun 1991 A
5630473 Nishishita May 1997 A
5875834 Brooks Mar 1999 A
6129144 Bousquet Oct 2000 A
6318455 Nakado et al. Nov 2001 B1
Foreign Referenced Citations (6)
Number Date Country
0 563 474 Oct 1993 EP
0 709 630 May 1996 EP
0 727 625 Aug 1996 EP
0 843 143 May 1998 EP
0 905 467 Mar 1999 EP
3-247993 Feb 1992 JP