U.S. patent number RE30,242 [Application Number 05/960,996] was granted by the patent office on 1980-04-01 for heat pump system.
This patent grant is currently assigned to Carrier Corporation. Invention is credited to Rudy C. Bussjager, James J. del Toro.
United States Patent |
RE30,242 |
del Toro , et al. |
April 1, 1980 |
Heat pump system
Abstract
A reversible vapor compression system having control means
associated therewith for automatically routing refrigerant through
the heat exchangers in response to a system mode of operation to
produce optimum system performance when the system is called upon
to produce either heating or cooling.
Inventors: |
del Toro; James J. (North
Syracuse, NY), Bussjager; Rudy C. (Syracuse, NY) |
Assignee: |
Carrier Corporation (Syracuse,
NY)
|
Family
ID: |
27110301 |
Appl.
No.: |
05/960,996 |
Filed: |
November 15, 1978 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
720721 |
Sep 7, 1976 |
04057975 |
Nov 15, 1977 |
|
|
Current U.S.
Class: |
62/324.6; 165/97;
62/324.2; 62/504 |
Current CPC
Class: |
F25B
13/00 (20130101); F25B 39/00 (20130101) |
Current International
Class: |
F25B
13/00 (20060101); F25B 39/00 (20060101); F25B
013/00 (); F25B 039/02 (); F28F 027/02 () |
Field of
Search: |
;62/324,504 ;165/97 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: King; Lloyd L.
Attorney, Agent or Firm: Curtin; J. Raymond Hayter; Robert
P.
Claims
What is claimed is: .[.1. In a heat pump system having a
compressor, a pair of heat exchangers and means for selectively
reversing the flow of refrigerant through the system so that the
function of the exchangers is also reversed, the improvement
comprising:
means for separating each exchanger into a plurality of heat
transfer zones, each zone containing a number of flow circuits,
flow control means for routing refrigerant discharged from the
compressor through each of the zones of one exchanger in a series
flow progression and routing the refrigerant discharged from said
one exchanger into the other exchanger simultaneously through each
of the zones of said other exchanger whereby flow is parallel
through the zones; and
switching means operatively associated with said flow control means
for automatically reversing the flow geometry through the
exchangers in response to reversing the flow of refrigerant through
the system whereby refrigerant flow is parallel through said one
exchanger and in series through said other exchanger..]. .[.2. The
heat pump system of claim 1 further including expansion means
associated with each of the exchanges for expanding refrigerant
flow from one of said exchangers to the other into each of the
circuits of said other exchanger..]. .[.3. A heat pump system
having a compressor, an indoor coil, an outdoor coil, a reversing
valve for delivering refrigerant discharged from the compressor to
the indoor coil during heating operations and to the outdoor coil
during cooling operations, the method of processing refrigerant
through the system including the steps:
separating the indoor and outdoor coils into a plurality of heat
transfer zones, each zone having a number of flow circuits passing
through the coil associated therewith;
routing the refrigerant delivered from the compressor to the
outdoor coil during the cooling operation so that refrigerant flows
through each of the heat transfer zones in a series
progression;
delivering the refrigerant discharged from the outdoor coil to each
of the heat transfer zones of the indoor coil simultaneously so
that the refrigerant flows through the zones in a parallel
flow;
returning the refrigerant from the indoor coil to the compressor to
complete the cycle; and
reversing the flow geometry through the indoor and outdoor coils in
response to a change in the systems operation whereby refrigerant
flow in series through the zones of the indoor coil and in parallel
through the zones of the outdoor coil..]. .[.4. The method of claim
3 further including the step of expanding the refrigerant directly
into each of the circuits of the heat transfer zones to establish a
parallel flow therethrough..]. .[.5. The method of claim 3 further
including the steps of arranging the number of circuits in each
heat transfer zone so that the number decreases in respect to the
direction of series flow through the exchanger..]. .[.6. The method
of claim 5 wherein the last zone in the series contains a single
circuit..]. .Iadd.7. A heat pump system having a compressor, an
indoor coil, an outdoor coil, a reversing valve for delivering
refrigerant discharged from the compressor to the indoor coil
during heating operations and to the outdoor coil during cooling
operations, the method of processing refrigerant through the system
including the steps of:
separating the indoor and outdoor coils into a plurality of heat
transfer zones, each zone having a number of flow circuits passing
through the coil associated therewith;
routing the refrigerant delivered from the compressor to the
outdoor coil during the cooling operation so that refrigerant flows
through each of the heat transfer zones in a series
progression;
delivering the refrigerant discharged from the outdoor coil to each
of the heat transfer zones of the indoor coil simultaneously so
that the refrigerant flows through the zones in a parallel
flow;
returning the refrigerant from the indoor coil to the compressor to
complete the cycle;
reversing the flow geometry through the indoor and outdoor coils in
response to a change in the systems operation whereby refrigerant
flow in series through the zones of the indoor coil in parallel
through the zones of the outdoor coil; and
arranging the number of circuits in each heat transfer zone so that
the number decreases in respect to the direction of series flow
through the exchanger. .Iaddend. .Iadd.8. The method of claim 7
wherein the last zone in the series contains a single circuit.
.Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to a reversible refrigeration system which
is adapted to deliver optimum performance in either a heating or a
cooling mode of operation.
More specifically, this invention relates to a heat pump having
control means associated therewith for automatically routing
refrigerant to each of the heat exchangers in response to the
exchangers' function whereby each exchanger operates efficiently
when called upon to serve either as a condenser or as an
evaporator.
Most air side heat exchangers employed in refrigeration systems are
of the plate fin construction wherein refrigerant is directed
through a number of heat transfer zones via flow circuits running
through the unit. When the exchanger is used as a condenser, the
flow of refrigerant is routed through the circuits so that it
passes in series through each zone. On the other hand, when the
exchanger is used as an evaporator, the refrigerant is generally
routed through each circuit simultaneously to establish a parallel
flow through the circuits. As can be seen, the flow geometry
associated with a well designed condenser is not compatible with
that of a well designed evaporator.
In a heat pump environment, it has been the usual practice to
compromise the heat exchanger design in order to permit the
exchangers to provide the double duty function required. This, in
turn, limited the performance of the entire system.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to improve heat
pump systems.
It is a further object of the present invention to provide a heat
pump system for automatically controlling the flow of refrigerant
through the system whereby the system performs effectively in
either a cooling or a heating mode of operation.
These and other objects of the present invention are attained by
means of a heat pump system having refrigerant flow control means
associated therewith to produce a series flow geometry through the
heat transfer zones of either of the heat exchangers when the
exchanger is serving as a condenser and a parallel flow geometry
through the zones when the exchanger is serving as an
evaporator.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention as well as
other objects and further features thereof, reference is had to the
following detailed description of the invention to be read in
connection with the accompanying drawings, wherein:
FIG. 1 is the schematic representation of a reversible refrigerant
system utilizing the heat exchanger of the present invention.
FIG. 2 is a partial perspective view showing a multicircuit heat
exchanger utilizing the teachings of the present invention.
FIG. 3 is a partial front view of the heat exchanger shown in FIG.
2.
FIG. 4 is an end view of the heat exchanger shown in FIG. 3.
FIG. 5 is a schematic representation illustrating the flow circuits
of the exchanger shown in FIGS. 2 through 4; and
FIG. 6 is an enlarged view in section illustrating a capillary tube
feeding one of the flow circuits of the exchanger shown in FIGS. 2
through 4.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 represents the simplest form of the invention being utilized
in a reversible vapor compression system, generally referenced 10.
The system includes a compressor 11 of any suitable design and two
refrigerant heat exchangers 12, 13 which are typically plate fin
coils which are specifically fabricated to exchange energy between
air moving over the plates and refrigerant moving through the
exchanger flow circuits. For purposes of this description, heat
exchanger 12 shall be referred to as the indoor coil while heat
exchanger 13 shall be referred to as the outdoor coil. The two
coils are operatively connected to the compressor by a four-way
valve 15, which enables the discharge vapor from the compressor to
be selectively directed into either one of the exchangers. When the
system is in a cooling mode of operation, the discharge is carried
via line 16 into a primary header 17 associated with the outdoor
coil. At this time, the suction end of the compressor is
operatively connected to the primary header 33 by means of line 36.
By cycling the four-way valve, the flow of refrigerant through the
system is reversed and, accordingly, the role of the heat
exchangers is also reversed.
The operation of the system shall be initially explained with the
system in a cooling mode of operation wherein the outdoor coil 13
is called upon to serve as a condenser. The refrigerant vapor
collected in the primary or upper header 17 flows downwardly
through the outdoor coil 13. The refrigerant is caused to move
through the heat transfer zones, an upper zone A and a lower zone
B. The two zones are separated by return bend 14 which functions as
an intermediate header for passing refrigerant from one zone to the
other.
After passing through the two heat transfer zones, the refrigerant
enters a lower secondary header 18 associated with the outdoor
coil. The lower header 18 is placed in fluid flow communication
with secondary header 31 associated with the indoor coil by means
of liquid line 23. It should also be noted that the lower header 18
is also placed in fluid flow communication with the upper header 17
by line 20 which by-passes the heat exchanger circuit. A check
valve 21 is positioned in the by-pass line. The valve is held
closed when the outdoor coil is operating as a condenser by the
pressure difference established over the exchanger as the
refrigerant changes from a vapor to a liquid. As a result, the
liquid refrigerant collected in the lower or secondary header is
prevented from flowing back into the primary header via line 20
when the exchanger is serving as a condenser.
The liquid refrigerant collected in header 18 moves along liquid
line 23 through another check valve 24. Check valve 24 is arranged
to open when the system is in a cooling mode of operation whereby
the liquid refrigerant is directed toward the indoor coil 12. A
second check valve 25 also is positioned in the liquid line close
to the secondary header 31 associated with the indoor coil. The
check valve 25 is arranged to operate in opposition with check
valve 24 whereby the refrigerant is precluded from flowing directly
from the liquid line into header 31. The refrigerant is thus forced
to move into a distributor 27 positioned forward of check valve 25
in relation to the direction of flow.
In the distributor, the flow is split into two separate flow paths
by means of a pair of capillary tubes 28, 29. As seen in FIG. 1,
the capillary tubes are passed into centrally located return bend
30 which serves as an intermediate header in regard to the indoor
coil. In practice the capillaries pass through the return bend and
empty deeply into the circuit tubing connected thereto. As a
result, a portion of the refrigerant is expanded into upper heat
transfer zone C and a portion expanded into lower heat transfer
zone D. Because of the pressures involved, a portion of the
refrigerant flows upwardly through the indoor coil 12 into the
primary header 33 and a portion of the refrigerant flows downwardly
into the secondary header 31. As can be seen, the flow geometry of
the indoor coil, which is functioning as an evaporator in the
cooling mode of operation, consists of two distinct flow passages
through which the refrigerant is moved simultaneously, one passage
carrying refrigerant through heat transfer zone C and the other
through heat transfer zone D.
As in the case of the outdoor exchanger, the indoor exchanger also
has a by-pass line 34 associated therewith which places the primary
header 33 in fluid flow communication with the secondary header 31.
A check valve 35 is located in the by-pass line and is arranged to
open when the exchanger 12 is operating as an evaporator. With
check valve 35 open, the two headers 31, 33 are exposed to the
suction side of the compressor by means of line 36 thereby
completing the cycle.
Changing the system mode of operation, which is accomplished by
cycling the four-way valve, reverses the flow of refrigerant
through the system. This in turn changes the function of the two
exchangers. At this time, the position of the four check valves
changes. By-pass line 20 is thus opened while line 34 is closed.
Similarly check valve 25 opens while check valve 24 closes.
The discharge from the compressor passes via line 36 and header 33
through the indoor coil, which is now acting as a condenser, into
the lower header 31. The refrigerant, as it moves through the
indoor coil, passes in series through the two heat transfer zones C
and D. From the header 31, the refrigerant moves down the liquid
line toward the outdoor coil. The flow is however blocked by closed
check valve 24 causing the refrigerant to move into distributor 37
where the flow is split into two paths by means of capillary tubes
38, 39.
The capillaries pass through the intermediate header or tube bend
14 into the circuits associated with heat transfer zones A and B.
Here again, the flow is split in two directions through the
exchanger with part of the flow directed into secondary header 18
and part into primary header 17. The two headers are connected to
the suction end of the compressor via open by-pass line 20 and line
16 to close the heating loop.
As should be clear from the description above, the flow of
refrigerant through the heat exchangers is automatically controlled
so that the flow geometry through each exchanger is changed
depending on whether the exchanger is being used as a condenser or
an evaporator. More specifically, when the heat exchanger is called
upon to serve as a condenser, refrigerant is caused to flow in
series through the exchanger heat zones. By the same token, the
refrigerant is caused to flow simultaneously, or in parallel,
through the heat zones when the exchanger is serving as an
evaporator. In this manner, the performance of the system can be
optimized for either a heating or cooling mode of operation, a
result heretofore unattainable because of limitations placed upon
the system as a result of the compromise necessitated by heat
exchanger design.
It should be clear from the description above that the system is
not necessarily limited by use of headers in connection with the
exchangers when the invention is carried out in connection with a
simple exchanger. In this regard the header can be replaced with
standard tubing capable of facilitating the movement of refrigerant
into and out of the exchangers.
Similarly, the present invention can be carried out in conjunction
with a complex coil in which a multitude of circuits are passed
back and forth through the exchanger unit. A complex coil, such as
those typically utilized in larger refrigeration systems as
illustrated in FIGS. 2 through 4. For purposes of explanation, the
coil shall be deemed to be an outdoor coil utilized in a reversible
refrigeration system similar to that described in FIG. 1.
A coil of complex circuitry containing a plurality of refrigerant
flow circuits is illustrated in FIGS. 2 through 4. The coil
includes two vertically aligned rows of finned tubes, an inner row
40 and outer row 41 which extend back and forth through the heat
exchanger. The rows are interconnected by return bends 42 to form a
number of individual refrigerant flow circuits of predetermined
geometry. Typically, the two terminal ends of each circuit are
brought out of the coil assembly through one of the assembly tube
sheets as for example tube sheet 45, so that both the entrance and
discharge opening to each circuit is conveniently located along one
side of the exchanger.
In the complex coil herein described, the coil contains seven flow
circuits that are arranged to pass through three heat transfer
zones. It should become obvious, however, from the discussion
below, that the number of circuits and heat transfer zones may vary
depending upon the capacity of the unit involved and other design
considerations.
Positioned along the side of the coil adjacent to the tube sheet 45
is a header network adapted to operate in conjunction with two
check valves to route the flow of refrigerant through the heat
exchanger in a prescribed manner when the exchanger is acting in
the system as a condenser and in a different manner when it is
acting as an evaporator. The header includes a primary header 47, a
dummy or intermediate header 48, a secondary header 49 and a liquid
header 46. It should be noted that the primary and secondary
headers are axially aligned with the interior chambers of each
header being separated by means of a check valve 51. The lower end
of primary header 47 is joined in fluid flow communication with a
compressor line 50 that is operatively connected to the compressor
by means of a four-way valve (not shown).
When the coil is serving as a condenser, high temperature and
pressure vapor is delivered into the primary header via line 50
thereby causing check valve 51 to close. The closing of the valve
in effect isolates the chamber of header 47 from that of header 49.
The now isolated primary header is thus caused to feed refrigerant
into four flow circuits by means of feeder tubes 52 operatively
associated therewith. The four circuits fed by header 47 are
positioned in the lower section of the coil make up a first heat
transfer zone, herein referenced zone E.
A simplified schematic illustration of the flow through the heat
exchanger is shown in FIG. 5. It is believed that the use of the
schematic in conjunction with the drawing of FIGS. 2 through 4 will
help in better understanding the flow geometry through the
exchanger. After passing through the four flow circuits making up
heat transfer zone E, the refrigerant is passed into the dummy
header 48 via discharge lines 53. Because of the pressure
differential involved, the refrigerant moves upwardly through the
dummy header and is discharged into the two uppermost circuits in
the coil by means of feeder tubes 54. The two upper refrigerant
flow circuits combine to establish a second, smaller heat transfer
region F.
After passing through the coil assembly, the refrigerant from the
two upper circuits is routed to the secondary header 49 via
discharge line 56. The refrigerant is collected in header 49 and
fed into the last flow circuit by means of a single feeder tube 58.
The last circuit passes through the third and final heat transfer
zone, zone G, and is discharged into the liquid header 46.
Preferably, the final heat transfer zone is located in the central
portion of the coil to enhance the heat transfer characteristics of
the coil. For the purpose of clarity, the final heat transfer zone
is illustrated at the top of the heat exchanger assembly.
The refrigerant, which is now in a liquid phase is collected in the
liquid header 46 and is passed through opened check valve 61 into a
T-connector 62. At the connector, the refrigerant moves down liquid
line 60 toward the indoor coil (not shown).
As can be seen from the description above, the header network,
acting in concert with the check valves, operates to direct the
refrigerant from the compressor through the heat transfer zones in
a series flow progression. Furthermore, the number of flow circuits
in each zone diminishes in the direction of flow. By zoning the
coil in this manner, the flow geometry of the coil is regulated in
response to the increase in density of the fluid to obtain optimum
coil performance when operating as a condenser.
When the systems mode of operation is reversed, the coil's function
is similarly reversed. In the heating mode, liquid refrigerant is
moved along liquid line 60 toward check valve 61. The valve,
however, is automatically moved to a closed position because of the
change in pressure felt over the valve. The refrigerant is thus
forced to move into distributor 63 that is connected to T-connector
62. At the distributor, the flow is separated into seven flow paths
by means of capillary tubes 65. It should be noted that the number
of capillary tubes are equal in number to the number of flow
circuits passing through the coil.
As best illustrated in FIG. 6, six of the capillary tubes pass
through the dummy header 48 and pass into feeder tubes 54
associated with the four circuits contained in heat transfer zone E
and the discharge tubes 53 associated with the two circuits
associated with heat transfer zone F. The capillary tubes extend
deeply into the various flow circuit tubes to insure that the
refrigerant passing through the capillaries is expanded well within
each circuit. This in turn, precludes the refrigerant from being
passed between circuits in the dummy header. Because the dummy
header is at a substantially uniform pressure, the refrigerant is
fed evenly into each circuit.
The seventh capillary tube is passed into the liquid header 46
which is at relatively the same pressure as the dummy header.
Header 46, in turn, feeds into the circuit associated with heat
transfer zone G.
It should be noted that a time check valve 51, positioned between
the primary and secondary headers 47 and 49 is now moved to an open
position so that the headers are cojoined to establish a single
flow passage leading to the compressor via line 50. As best
illustrated in FIG. 5, the seven flow circuits are arranged to
empty into the headers 47, 49 when the coil is serving as an
evaporator. The circuits associated with zones G and F empty into
header 49 via lines 56 and 58 while the four circuits associated
with zone E empty into header 47 via lines 52.
Accordingly, when the heat exchanger is called upon to serve as an
evaporator in the system, the flow geometry through the coil is
automatically changed whereby refrigerant is caused to flow through
all the circuits, and thus all the heat transfer zones,
simultaneously in a parallel flow arrangement. By maintaining this
parallel flow arrangement through the coil, optimum performance of
the exchanger can be obtained when utilized as an evaporator.
While this invention has been described with reference to the
structure herein disclosed, it is not confined to the specific
details as set forth. For example, in place of the capillary tubes
wherein employed any expansion device capable of carrying out the
flow splitting and throttling process can be similarly employed
provided such modifications come within the scope of the following
claims.
* * * * *