U.S. patent application number 13/114405 was filed with the patent office on 2011-12-01 for orientation insensitive refrigerant distributor tube.
This patent application is currently assigned to DELPHI TECHNOLOGIES, INC.. Invention is credited to RUSSELL SCOTT JOHNSON, Shrikant Mukund Joshi, DOUGLAS WINTERSTEEN, YANPING XIA.
Application Number | 20110290465 13/114405 |
Document ID | / |
Family ID | 44583632 |
Filed Date | 2011-12-01 |
United States Patent
Application |
20110290465 |
Kind Code |
A1 |
Joshi; Shrikant Mukund ; et
al. |
December 1, 2011 |
ORIENTATION INSENSITIVE REFRIGERANT DISTRIBUTOR TUBE
Abstract
A heat exchanger assembly having an inlet header, an outlet
header spaced from the inlet header, a plurality of refrigerant
tubes hydraulically connecting the inlet header with the outlet
header. A distributor tube having a plurality of orifices disposed
in the inlet header, wherein the orifices are arranged along the
distributor tube such that at least one orifice is oriented in the
liquid phase of the refrigerant pressed against the internal
surface of the distributor tube regardless of orientation of the
evaporator. The orifices may be arranged in a random order about
the distributor tube, positioned in groups of at least two at
predetermined locations, or spiraled along the distributor
tube.
Inventors: |
Joshi; Shrikant Mukund;
(WILLIAMSVILLE, NY) ; WINTERSTEEN; DOUGLAS; (BURT,
NY) ; JOHNSON; RUSSELL SCOTT; (TONAWANDA, NY)
; XIA; YANPING; (NORTH TONAWANDA, NY) |
Assignee: |
DELPHI TECHNOLOGIES, INC.
TROY
MI
|
Family ID: |
44583632 |
Appl. No.: |
13/114405 |
Filed: |
May 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61350123 |
Jun 1, 2010 |
|
|
|
Current U.S.
Class: |
165/175 |
Current CPC
Class: |
F28F 9/0273 20130101;
F28D 2021/0071 20130101; F28D 2001/0273 20130101; F28D 1/05383
20130101 |
Class at
Publication: |
165/175 |
International
Class: |
F28F 9/02 20060101
F28F009/02 |
Claims
1. A heat exchanger assembly for use with a two-phase refrigerant,
comprising; an inlet header; an outlet header spaced from said
inlet header; a plurality of refrigerant tubes hydraulically
connecting said inlet header to said outlet header; a distributor
tube having a plurality of orifices disposed in said inlet header,
wherein said orifices are arranged along said distributor tube such
that at least one orifice is oriented in the liquid phase of the
refrigerant pressed against said internal surface of said
distributor tube regardless of orientation of said heat exchanger
assembly.
2. A heat exchanger assembly of claim 1, wherein each of said
plurality of orifices is randomly positioned along said distributor
tube.
3. A heat exchanger assembly of claim 1, wherein said plurality of
orifices is spirally positioned along said distributor tube about a
substantially center axis.
4. A heat exchanger assembly of claim 3, wherein each of said
plurality of orifices is off-set 45 to 180 degrees from adjacent
said orifices.
5. A heat exchanger assembly of claim 3, wherein each of said
plurality of orifices is off-set 90 degrees from adjacent
orifices.
6. A heat exchanger assembly of claim 3, wherein each of said
plurality of orifices is off-set 180 degrees from adjacent
orifices.
7. A heat exchanger assembly of claim 1, wherein said distributor
tube extends along a substantially center axis and includes pairs
of said orifices spaced along said distributor tube; wherein each
of said pairs of orifices is located about a respective point on
said center axis.
8. A heat exchanger assembly of claim 7, wherein said pair of
orifices includes one orifice that is 90 to 180 degrees apart from
the other orifice.
9. A heat exchanger assembly of claim 7, wherein said pair of
orifices includes one orifice that is 90 degrees from the other
orifice.
10. A heat exchanger assembly of claim 9, wherein each of said
pairs of orifices is 90 degrees rotated from adjacent said pairs of
orifices.
11. A heat exchanger assembly of claim 9, wherein each of said
pairs of orifices is 180 degrees rotated from adjacent said pairs
of orifices.
12. A heat exchanger assembly of claim 7, wherein said pair of
orifices includes one orifice that is 180 degrees from the other
orifice.
13. A heat exchanger assembly of claim 12, wherein each of said
pairs of orifices is 90 degrees rotated from adjacent said pairs of
orifices.
14. A heat exchanger assembly of claim 1, wherein said distributor
tube extends along a substantially center axis and includes groups
of 4 orifices spaced along said distributor tube.
15. A heat exchanger assembly of claim 14, wherein each orifice
within said group of (4) orifices is 90 degrees from said adjacent
orifices.
16. A heat exchanger assembly of claim 15, wherein each group of 4
orifices is 45 degrees rotated from adjacent group of 4 orifices.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/350,123 for an ORIENTATION
INSENSITIVE REFRIGERANT DISTRIBUTION TUBE, filed on Jun. 1, 2010,
which is hereby incorporated by reference in its entirety.
TECHNICAL FIELD OF INVENTION
[0002] The present disclosure relates to an inlet distributor for
an evaporator; more particularly to an inlet distributor having a
plurality of orifices arranged along the length of the distributor
tube.
BACKGROUND OF INVENTION
[0003] Residential and commercial air conditioning and heat pump
systems are known to employ modified automotive heat exchangers,
which are desirable for its proven high heat transfer efficiency,
durability, and relatively ease of manufacturability. Automotive
heat exchangers typically include an inlet header, an outlet
header, and a plurality of refrigerant tubes hydraulically
connecting the headers for refrigerant flow therebetween.
Corrugated fins interconnect adjacent refrigerant tubes to increase
the available heat transfer area, as well as to increase the
structural integrity of the heat exchanger. The coil of the heat
exchanger is defined by the refrigerant tubes and interconnecting
corrugated fins.
[0004] To meet the demands of residential and commercial
applications, the size of the coil of the heat exchanger has to be
increased accordingly, which in turn dramatically increased the
lengths of the inlet and outlet headers. For a heat exchanger
operating in evaporator mode, the increased length of the headers
tends to result in refrigerant mal-distribution through the
refrigerant tubes. Momentum and gravity effects, due to the large
mass differences between the liquid and gas phases, can result in
separation of the phases in the inlet header and cause poor
refrigerant distribution through the refrigerant tubes. Poor
refrigerant distribution degrades evaporator performance and can
result in uneven temperature distribution over the coil. To assist
in providing uniform refrigerant distribution though the
refrigerant tubes, it is known to provide a distributor tube in the
inlet header.
[0005] A typical distributor tube extends the length of the inlet
header and includes a plurality of uniformly spaced orifices for
distributing the two-phase refrigerant throughout the length of the
header. The orifices are oriented at a designed angle relative to
the center of the cross-section of the refrigerant tube to provide
the maximum performance for the coil in a specific application.
Typically, the angle of the orifices is selected based on testing a
vertical slab coil design with the refrigerant tube aligned in the
opposite direction of gravity.
[0006] Indoor evaporators also have the additional challenge of
packaging constraints; the evaporators have to fit within the
limited volume offered by the plenums of residential HVAC systems.
In a slab coil design, the refrigerant tubes lie in a plane much
like that of an automotive heat exchanger, and for maximum
efficiency it is preferable that the refrigerant tubes are aligned
in the direction of gravity with the inlet header lower than the
outlet header. To provide the cooling capacity required within a
limited space, two smaller slab coils are assembled into an A-Frame
design or a single larger slab coil is bent into an ARC design. The
A-Frame design or ARC design may need to be installed in various
orientations with respect to gravity, in which the refrigerant
tubes may not be aligned in the direction of gravity and the inlet
header may not be lower than the outlet header. The desired
distribution of refrigerant flowing through the coil may be
adversely affected due to the orientation of the evaporator. There
is a long felt need for an evaporator that provides good
refrigerant distribution regardless of its orientation.
SUMMARY OF THE INVENTION
[0007] The invention relates to a heat exchanger assembly having an
inlet header, an outlet header spaced from the inlet header, a
plurality of refrigerant tubes hydraulically connecting the inlet
header with the outlet header. A distributor tube having a
plurality of orifices disposed in the inlet header, wherein the
orifices are arranged along the distributor tube such that at least
one orifice is oriented in the liquid phase of a two-phased
refrigerant pressed against the internal surface of the distributor
tube regardless of the orientation of the evaporator.
[0008] According to one aspect of the invention, the orifices may
be substantially uniformly spaced along the length of the
distributor tube in pairs or groups of four (4). Within each pair
of orifices, one of the orifices may be oriented 90 to 180 degrees
apart from the other with respect to the pair's respective point on
a central axis. Each pair of orifices may be rotated 90 to 180
degrees from the adjacent pair of orifices. For groups of four (4)
orifices, each of the orifices may be oriented 90 degrees apart
from the adjacent orifice with respect to the group's respective
point on a central axis. Each group of four (4) orifices may be
rotated 45 degrees from the adjacent group of four (4)
orifices.
[0009] In another aspect of the invention, the cylindrical
refrigerant distributor tube may have a plurality of orifices
spiraled along the tube. With respect to an end view of the central
axis, each succeeding orifice may be offset 45 to 180 degrees from
the preceding orifice.
[0010] The above configurations of orifices on the distributor tube
provide that at least one of the orifices will be located within
the liquid phase of the two-phase refrigerant flowing through the
distributor tube regardless of the final orientations of the
evaporator coil. This provides at least the advantage of improved
refrigerant distribution through the refrigerant tube of the heat
exchanger assembly resulting in improved heat transfer
efficiency.
BRIEF DESCRIPTION OF DRAWINGS
[0011] This invention will be further described with reference to
the accompanying drawings in which:
[0012] FIGS. 1A-C show representative end views of an A-type coil
or bent coil design evaporator.
[0013] FIG. 2 shows a distributor tube in an inlet header of an
evaporator, in which the orifices of the distributor tube are
oriented in a direction opposite that of the direction of
gravity.
[0014] FIG. 3 shows a distributor tube in an inlet header of an
evaporator, in which the orifices of the distributor tube are
oriented in the direction of gravity.
[0015] FIG. 4 shows a cross-section of the inlet header having a
distributor tube with the liquid phase of refrigerant pressed-up
against the interior surface of the distributor tube.
[0016] FIG. 5 shows a refrigerant distributor tube having groups of
two (2) orifices along the length of the distributor tube, wherein
the orifices in each group are oriented 180 degrees apart from each
other and the groups of two (2) orifices are rotated 90 degrees
apart from each other.
[0017] FIG. 6 shows a refrigerant distributor tube having groups of
four (4) orifices along the length of the distributor tube, wherein
the orifices in each group are oriented 90 degrees apart from each
other.
[0018] FIG. 7 shows a refrigerant distributor tube having a
plurality of orifices spiraled along the tube at an exemplary 90
degrees between adjacent orifices.
DETAILED DESCRIPTION OF INVENTION
[0019] For a typical slab coil design evaporator, the desired angle
of the orifices of a distributor tube is selected based on testing
of a vertical slab coil in which the refrigerant tubes are aligned
in the direction of gravity with the inlet header lower than the
outlet header. To accommodate the packaging constraints required
for residential applications, a residential indoor evaporator may
be constructed by using two slab coils in an A-Frame design or a
single slab coil bent into an ARC design. Shown in FIGS. 1A-1C are
representations of an end view of an A-Frame design or ARC design
residential indoor evaporator 10 having an inlet header 12a, an
outlet header 12b spaced apart from the inlet header 12a, and a
plurality of refrigerant tubes 14 hydraulically connecting the
headers 12a, 12b for refrigerant flow. An evaporator coil 16,
partially shown in FIGS. 2 and 3, is defined by the plurality of
refrigerant tubes 14 together with external fins 15 interconnecting
the adjacent refrigerant tubes 14. The evaporator 10 includes a
distributor tube 20 in the inlet header 12a, shown in FIGS. 2-7,
for improved refrigerant distribution. The above mentioned
components of the evaporator 10 are typically constructed of a heat
conductive material such as aluminum.
[0020] Each of the A-Frame design and ARC design provides an
evaporator 10 having at least one apex 18. The A-Frame or ARC
design can be installed within a HVAC plenum in various
orientations with respect to the direction of gravity, in which the
apex 18 may be up, down, horizontal, and any other orientation
therebetween. With these varieties of possible orientations, the
inlet header 12a may be located above the outlet header 12b, below
the outlet header 12b, or horizontal with the outlet header 12b.
The headers 12a, 12b are typically perpendicular to that of the
direction of gravity, but the bottom header may be slightly angled
toward the direction of gravity to facilitate condensate
drainage.
[0021] A standard angle designed for the orifices 22 of the
distribution tube 20 relative to the refrigerant tube 14 may not
necessarily work efficiently when used in all the various potential
orientations of the evaporator 10. It was found that only certain
range of angles of the orifices 22 of the distribution tube 20
relative to the refrigerant tube 14 are acceptable for each of the
various evaporator coil 16 orientations. In other words, orifice
angles are application specific; therefore, the desired orifice
range of angles has to be calculated for each specific orientation
of the evaporator 10.
[0022] With reference to FIGS. 2-4, it is believed that the liquid
phase 24 of a two-phase refrigerant flowing through the distributor
tube 20 tends to migrate to the bottom of the interior surface 28
of the distributor tube 20 due to gravity. It is suspected that the
liquid phase 24 does not necessary puddle on the bottom or low spot
of the distribution tube 20, but instead it is pressed against and
rides up a portion of the interior surface 28 of the distributor
tube 20 by the flow of refrigerant through the distributor tube 20,
thereby forming a liquid refrigerant cross-sectional profile 30
much like a crescent moon with its apex on the bottom. The limit
would be annular flow where the liquid distributes around the
entire peripheral internal surface 28 of the distribution tube 20,
but more typically a thicker layer would exist on the bottom.
[0023] It was found that if the orifices 22 were facing in a
direction other than between 45 to 315 degrees with respect to the
opposite direction of gravity being 0 degree, mostly vapor phase
refrigerant tend to exits the orifices 22 migrating toward the
refrigerant tubes 14. This is undesirable because optimal heat
transfer efficiency is obtained when the refrigerant entering the
refrigerant tubes is in a substantially liquid phase.
[0024] With reference to FIG. 3, it was surprisingly found that
when the orifices 22 are oriented substantially in the direction of
gravity, the pressure and momentum of the refrigerant flowing
through the distributor tube 20 pushes the liquid phase refrigerant
out of the distributor tube 20 through the orifices 22 toward the
refrigerant tubes. The refrigerant remains substantially in liquid
phase until it reaches the refrigerant tubes 14, at which point the
liquid phase refrigerant starts to absorb heat and vaporizes,
thereby providing optimum heat transfer and even temperature
distribution across the evaporator coil 16. With reference to FIG.
4, during periods of high refrigerant flow, the liquid refrigerant
cross-sectional profile 30 occupies the interior surface 28 of the
distributor tube 20 from 45 to 315 degrees with respect to the
opposite direction of gravity being 0 degree. During normal
operating conditions, the liquid refrigerant cross-sectional
profile 30 occupies the interior surface 28 of the distributor tube
20 from 90 to 270 degrees.
[0025] An aspect of the invention provides a means to transport the
liquid phase refrigerant from the distributor tube 20 to the
refrigerant tubes 14 for efficient boiling and thus improved heat
transfer performance regardless of the orientation of the A-Frame
or ARC evaporator coil evaporator. This can be achieved by having
orifices 22 at angles from 45 to 315 degrees, preferably between 90
to 270 degrees, with respect to the opposite direction of gravity
being 0 degree, along the distributor tube 20 to ensure that at
least one, but preferably a group, of orifices 22 is substantially
oriented within the liquid refrigerant cross-sectional profile 30.
By having one or more orifices within the liquid profile 30, the
refrigerant flowing through the distributor tube 20 will push the
liquid phase refrigerant through the orifices 22 and toward the
refrigerant tubes.
[0026] FIG. 5 shows a cylindrical refrigerant distributor tube 20
extending along a substantially central axis (A-axis). Pairs of
orifices 22 are substantially uniformly spaced along the length of
the distributor tube 20, in which each pair of orifices 22 is
located about its respective point on the A-axis. Within each pair
of orifices 22, one of the orifices 22 may be oriented 90 to 180
degrees apart from the other with respect to the pair's respective
point on the A-axis. Furthermore, each pair of orifices 22 may be
rotated 90 to 180 degrees from the adjacent pair of orifices
22.
[0027] FIG. 6 shows a cylindrical refrigerant distributor tube 20
extending along the A-axis. Groups of four (4) orifices 22 are
substantially uniformly spaced along the length of the distributor
tube 20, in which each group of orifices 22 is located about its
respective point on the A-axis. Within each group of four (4)
orifices 22, each of the orifices 22 may be oriented 90 degrees
apart from the adjacent orifice 22 with respect to the group's
respective point on the A-axis. Furthermore, each group of (4)
orifices 22 may be rotated 45 degrees from the adjacent group of
(4) orifices 22.
[0028] FIG. 7 shows a cylindrical refrigerant distributor tube 20
having a plurality of orifices 22 spiraled along the tube. With
respect to an end view of the A-axis, each succeeding orifice 22
may be offset 45 to 180 degrees from the preceding orifice 22.
[0029] With the above configurations of orifices 22 on the
distributor tube 20 or any configuration that provides at least one
orifice 22 in the desired direction regardless of the orientation
of the evaporator 10 would improve the distribution of refrigerant
though the refrigerant tubes 14. Therefore, if the evaporator coil
16 is positioned in any one of the various possible orientations,
at least one of the orifices 22 would be located within the liquid
refrigerant cross-sectional profile 30.
[0030] While this invention has been described in terms of the
preferred embodiments thereof, it is not intended to be so limited,
but rather only to the extent set forth in the claims that
follow.
* * * * *