U.S. patent application number 17/187874 was filed with the patent office on 2021-06-17 for heat pump with dehumidification.
The applicant listed for this patent is Climate Master, Inc.. Invention is credited to Puya Javidmand, Michael F. Taras.
Application Number | 20210180807 17/187874 |
Document ID | / |
Family ID | 1000005429888 |
Filed Date | 2021-06-17 |
United States Patent
Application |
20210180807 |
Kind Code |
A1 |
Taras; Michael F. ; et
al. |
June 17, 2021 |
HEAT PUMP WITH DEHUMIDIFICATION
Abstract
Various embodiments of a heat pump system are disclosed to
provide improved and flexible heat pump operation when
dehumidification of the conditioned space is required. In one
embodiment, a heat pump system includes a heat pump loop comprising
a refrigerant circuit that fluidly interconnects (1) a compressor;
(2) a source heat exchanger; (3) a source heat exchanger bypass
circuit comprising a bypass valve; (4) a space heat exchanger; (5)
a reversing valve positioned on the discharge side of the
compressor; (6) a reheat circuit comprising a reheat heat
exchanger; (7) first and second expansion devices; and (8) first
and second expansion device bypass circuits configured to allow
refrigerant to bypass the first and second expansion devices,
respectively, where the first and second bypass circuits include
first and second check valves, respectively; and (9) a 3-way valve
configured to selectively direct refrigerant flow to the first
expansion device, the reheat circuit, and the second expansion
device.
Inventors: |
Taras; Michael F.; (Oklahoma
City, OK) ; Javidmand; Puya; (Oklahoma City,
OK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Climate Master, Inc. |
Oklahoma City |
OK |
US |
|
|
Family ID: |
1000005429888 |
Appl. No.: |
17/187874 |
Filed: |
February 28, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16213338 |
Dec 7, 2018 |
10935260 |
|
|
17187874 |
|
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|
62597719 |
Dec 12, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 2313/0212 20130101;
F25B 41/26 20210101; F25B 13/00 20130101; F25B 6/04 20130101; F25B
2400/0403 20130101; F24F 2003/1446 20130101; F25B 2313/005
20130101; F25B 40/02 20130101; F24F 11/0008 20130101; F24F 3/1405
20130101; F25B 41/20 20210101; F25B 30/02 20130101; F24F 2003/1452
20130101; F25B 2313/0292 20130101; F24F 3/153 20130101; F25B 41/31
20210101; F25B 2400/0411 20130101 |
International
Class: |
F24F 3/14 20060101
F24F003/14; F25B 30/02 20060101 F25B030/02; F24F 11/00 20060101
F24F011/00; F24F 3/153 20060101 F24F003/153; F25B 6/04 20060101
F25B006/04; F25B 40/02 20060101 F25B040/02; F25B 13/00 20060101
F25B013/00; F25B 41/20 20060101 F25B041/20; F25B 41/26 20060101
F25B041/26; F25B 41/31 20060101 F25B041/31 |
Claims
1. A heat pump system for conditioning air in a space, comprising:
a heat pump loop comprising a refrigerant circuit that fluidly
interconnects: a compressor; a source heat exchanger for exchanging
heat with a source liquid; a space heat exchanger for cooling or
heating the air in the space; a reversing valve configured to
alternately direct refrigerant flow from the compressor to one of
the source heat exchanger and the space heat exchanger and to
alternately return flow from the other of the source heat exchanger
and the space heat exchanger to the compressor; a reheat circuit
comprising a reheat heat exchanger, an upstream leg, a downstream
leg, and a reheat bypass valve joining the upstream leg and the
downstream leg, wherein the reheat heat exchanger is configured to
reheat the air when the system is in a dehumidification mode and
operate as an auxiliary condenser when the system is in a heating
mode, wherein the space heat exchanger and the reheat heat
exchanger are positioned in an air flow path for conditioning the
air in the space; an expansion device positioned downstream of the
source heat exchanger and upstream of the space heat exchanger; a
3-way valve positioned between the compressor, the reversing valve,
and the reheat heat exchanger and configured to direct refrigerant
flow from the compressor and selectively to the reversing valve and
to the reheat heat exchanger, wherein the reheat bypass valve is
positioned between the 3-way valve and the reversing valve to
modulate refrigerant flow through the reheat heat exchanger.
2. The heat pump system of claim 1, wherein the compressor is a
variable speed compressor.
3. The heat pump system of claim 1, wherein the source heat
exchanger is a refrigerant-to-liquid source heat exchanger.
4. The heat pump system of claim 1, wherein the space heat
exchanger is a refrigerant-to-air space heat exchanger.
5. The heat pump system of claim 1, wherein the source heat
exchanger is operable as either a condenser or an evaporator.
6. The heat pump system of claim 5, wherein the space heat
exchanger is operable as either a condenser or an evaporator.
7. The heat pump system of claim 1, wherein the expansion device is
a bi-directional expansion device.
8. The heat pump system of claim 7, wherein the bi-directional
expansion device is an electronic bi-directional expansion
device.
9. The heat pump system of claim 1, wherein the reheat bypass valve
is bi-directional.
10. The heat pump system of claim 1, including a variable-capacity
liquid pump configured to circulate the source liquid to or from
the source heat exchanger.
11. The heat pump system of claim 1, including a variable airflow
fan associated with the space heat exchanger.
12. The heat pump system of claim 1, wherein to operate the system
in a cooling mode: the 3-way valve is configured to inactivate the
reheat circuit and direct refrigerant flow from the compressor and
to the reversing valve; and the reversing valve is configured to
direct refrigerant flow from the 3-way valve to the source heat
exchanger and to return flow from the space heat exchanger to the
compressor.
13. The heat pump system of claim 12, wherein the reheat circuit
further includes a shutoff leg along the downstream leg to prevent
hot gas discharged from the compressor from entering the reheat
circuit when the system is operating in the cooling mode.
14. The heat pump system of claim 1, wherein to operate the system
in the dehumidification mode: the 3-way valve is configured to
direct refrigerant flow from the compressor to the reheat circuit
and subsequently to the reversing valve; and the reversing valve is
configured to direct refrigerant flow from the reheat circuit to
the source heat exchanger and to return flow from the space heat
exchanger to the compressor.
15. The heat pump system of claim 1, wherein to operate the system
in the heating mode: the 3-way valve is configured to direct
refrigerant flow from the compressor to the reheat circuit and
subsequently to the reversing valve; and the reversing valve is
configured to direct refrigerant flow from the reheat circuit to
the space heat exchanger and to return flow from the source heat
exchanger to the compressor.
16. The heat pump system of claim 1, further including a controller
comprising a processor and memory on which one or more software
programs are stored, the controller configured to control operation
of the reversing valve, the reheat bypass valve, the 3-way valve,
the expansion device, and the compressor.
17. The heat pump system of claim 16, wherein to operate the system
in a cooling mode, the controller is configured to: control the
3-way valve to inactivate the reheat circuit and to cause
refrigerant flow from the compressor and to the reversing valve;
and control the reversing valve to cause refrigerant flow from the
3-way valve to the source heat exchanger and to return flow from
the space heat exchanger to the compressor.
18. The heat pump system of claim 16, wherein to operate the system
in the dehumidification mode, the controller is configured to:
control the 3-way valve to cause refrigerant flow from the
compressor to the reheat circuit and subsequently to the reversing
valve; and control the reversing valve to cause refrigerant flow
from the reheat circuit to the source heat exchanger and to return
flow from the space heat exchanger to the compressor.
19. The heat pump system of claim 16, wherein to operate the system
in the heating mode, the controller is configured to: control the
3-way valve to cause refrigerant flow from the compressor to the
reheat circuit and subsequently to the reversing valve; and control
the reversing valve to cause refrigerant flow from the reheat
circuit to the space heat exchanger and to return flow from the
source heat exchanger to the compressor.
20. The heat pump system of claim 16, wherein the controller is
configured to control an opening of the reheat bypass valve to
modulate refrigerant flow through the reheat heat exchanger.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 16/213,338, filed Dec. 7, 2018, which claims the benefit of
U.S. Provisional Patent Application No. 62,597,719, filed Dec. 12,
2017, all of which are incorporated by reference herein in their
entirety.
BACKGROUND
[0002] The instant disclosure relates generally to heating,
ventilation, and air conditioning systems and methods and, more
particularly but without limitation, to heat pump systems.
SUMMARY
[0003] Disclosed are various embodiments of heat pump systems and
methods of operating the heat pump systems for conditioning air in
a space.
[0004] In one embodiment, a heat pump system for conditioning air
in a space includes a heat pump loop comprising a refrigerant
circuit that fluidly interconnects: (1) a compressor having a
discharge outlet port and an inlet suction port; (2) a source heat
exchanger operable as either a condenser or an evaporator; (3) a
source heat exchanger bypass circuit comprising a bypass valve to
modulate refrigerant flow through the source heat exchanger; (4) a
space heat exchanger operable as either an evaporator or a
condenser for cooling or heating the air in the space; (5) a
reversing valve positioned on the discharge side of the compressor
and configured to alternately direct refrigerant flow from the
discharge outlet port of the compressor to one of the source heat
exchanger and the space heat exchanger and to alternately return
flow from the other of the source heat exchanger and the space heat
exchanger to the suction inlet port of the compressor; (6) a reheat
circuit comprising a reheat heat exchanger to reheat the air when
the system is in a dehumidification mode, and operable to act as an
auxiliary condenser when the system is in a heating mode, where the
space heat exchanger and the reheat heat exchanger are positioned
in an air flow path for conditioning the air in the space; (7)
first and second expansion devices; and (8) first and second
expansion device bypass circuits configured to allow refrigerant to
bypass the first and second expansion devices, respectively, the
first and second bypass circuits comprising first and second check
valves, respectively, to control a direction of refrigerant flow in
the first and second bypass circuits; and (9) a 3-way valve
configured to selectively direct refrigerant flow to the first
expansion device, the reheat circuit, and the second expansion
device.
[0005] The compressor may be a variable capacity compressor. The
heat pump system may include a liquid pump associated with the
source heat exchanger and the pump may be a variable capacity pump.
The heat pump system may include a fan associated with the space
heat exchanger and the fan may be a variable airflow fan. The
bypass valve may be bi-directional. The first and second expansion
devices may be fixed orifice devices, mechanical valves, or
electronic valves. The first expansion device may be positioned
between the source heat exchanger and the 3-way valve. The second
expansion device may be positioned between the reheat circuit and
the space heat exchanger. The reheat circuit may include a reheat
bypass valve to modulate refrigerant flow through the reheat heat
exchanger.
[0006] The heat pump system may include a controller comprising a
processor and memory on which one or more software programs are
stored, the controller configured to control operation of the
reversing valve, the bypass valve, the 3-way valve, and the first
and second expansion devices, the compressor, the liquid pump for
circulating water or brine solution through the source heat
exchanger, and the fan for flowing air over the space heat
exchanger and the reheat heat exchanger.
[0007] To operate the system in a cooling mode, the controller may
be configured to: (a) close the bypass valve to cause refrigerant
flow through the source heat exchanger; (b) close the first
expansion device to cause refrigerant flow through the first
expansion device bypass circuit and the first check valve; (c)
control the 3-way valve to inactivate the reheat circuit and to
cause refrigerant flow to the second expansion device; (d) control
an opening of the second expansion device to cause refrigerant flow
through the second expansion device, and thereafter, the space heat
exchanger, wherein an orientation of the second check valve
prohibits flow of refrigerant through the second expansion device
bypass circuit; and (e) control the reversing valve to cause
refrigerant flow from the discharge outlet port of the compressor
to the source heat exchanger and to return flow from the space heat
exchanger to the suction inlet port of the compressor.
[0008] To operate the system in the dehumidification mode, the
controller may be configured to: (a) control an opening of the
bypass valve to modulate refrigerant flow through the source heat
exchanger and through the source heat exchanger bypass circuit; (b)
close the first expansion device to cause refrigerant flow through
the first expansion device bypass circuit and the first check
valve; (c) control the 3-way valve to cause refrigerant flow from
the first expansion device bypass circuit to the reheat circuit,
and thereafter, to the second expansion device; (d) control an
opening of the second expansion device to cause refrigerant flow
through the second expansion device, and thereafter, the space heat
exchanger, wherein an orientation of the second check valve
prohibits flow of refrigerant through the second expansion device
bypass circuit; and (e) control the reversing valve to cause
refrigerant flow from the discharge outlet port of the compressor
to the source heat exchanger and to return flow from the space heat
exchanger to the suction inlet port of the compressor. The
controller may be configured to control an opening of a reheat
bypass valve positioned along the reheat circuit to modulate
refrigerant flow through the reheat heat exchanger.
[0009] To operate the system in the heating mode, the controller
may be configured to: (a) control the reversing valve to cause
refrigerant flow from the discharge outlet port of the compressor
to the space heat exchanger and to return flow from the source heat
exchanger to the suction inlet port of the compressor; (b) close
the second expansion device to cause refrigerant flow through the
second expansion device bypass circuit and the second check valve,
and thereafter, the reheat heat exchanger; (c) control the 3-way
valve to cause refrigerant flow in the reheat circuit, and
thereafter, to the first expansion device; (d) control an opening
of the first expansion device to cause refrigerant flow through the
first expansion device, wherein an orientation of the first check
valve prohibits flow of refrigerant through the first expansion
device bypass circuit; and (e) close the bypass valve to cause
refrigerant flow through the source heat exchanger. The controller
may be configured to control an opening of a reheat bypass valve
positioned along the reheat circuit to modulate refrigerant flow
through the reheat heat exchanger.
[0010] In one embodiment, a method of conditioning air in a space
is disclosed, comprising the steps of: (1) providing a heat pump
loop comprising a refrigerant circuit that fluidly interconnects
(a) a compressor having a discharge outlet port and an inlet
suction port; (b) a source heat exchanger operable as either a
condenser or an evaporator; (c) a source heat exchanger bypass
circuit comprising a bypass valve to modulate refrigerant flow
through the source heat exchanger; (d) a space heat exchanger
operable as either an evaporator or a condenser for cooling or
heating the air in the space; (e) a reversing valve positioned on
the discharge side of the compressor and configured to alternately
direct refrigerant flow from the discharge outlet port of the
compressor to one of the source heat exchanger and the space heat
exchanger and to alternately return flow from the other of the
source heat exchanger and the space heat exchanger to the suction
inlet port of the compressor; (f) a reheat circuit comprising a
reheat heat exchanger to reheat the air when the system is in a
dehumidification mode, and operable to act as an auxiliary
condenser when the system is in a heating mode, wherein the space
heat exchanger and the reheat heat exchanger are positioned in an
air flow path for conditioning the air in the space; (g) first and
second expansion devices; (h) first and second expansion device
bypass circuits configured to allow refrigerant to bypass the first
and second expansion devices, respectively, the first and second
bypass circuits comprising first and second check valves,
respectively, to control a direction of refrigerant flow in the
first and second bypass circuits; (i) a 3-way valve configured to
selectively direct refrigerant flow to the first expansion device,
the reheat circuit, and the second expansion device; and (2)
operating a control system configured to operate the heat pump loop
in a plurality of modes in response to air conditioning demands in
the space, wherein the plurality of modes includes a cooling mode,
the heating mode, and the dehumidification mode.
[0011] In connection with the foregoing method, the compressor may
be a variable capacity compressor; the bypass valve may be
bi-directional; the heat pump system may include a liquid pump
associated with the source heat exchanger and the pump may be a
variable capacity pump; the heat pump system may include a fan
associated with the space heat exchanger and the fan may be a
variable airflow fan; the first and second expansion devices may be
fixed orifice devices, mechanical valves, or electronic valves; the
first expansion device may be positioned between the source heat
exchanger and the 3-way valve; the second expansion device may be
positioned between the reheat circuit and the space heat exchanger;
the reheat circuit may include a reheat bypass valve to modulate
refrigerant flow through the reheat heat exchanger; and the reheat
circuit may include a reheat bypass valve to modulate refrigerant
flow through the reheat heat exchanger.
[0012] The control system may include a controller comprising a
processor and memory on which one or more software programs are
stored, the controller configured to control operation of the
reversing valve, the bypass valve, the 3-way valve, and the first
and second expansion devices, the compressor, the liquid pump for
circulating water or brine solution through the source heat
exchanger, and the fan for flowing air over the space heat
exchanger and the reheat heat exchanger.
[0013] Operating the controller in the cooling mode may include the
steps of: (i) closing the bypass valve to cause refrigerant flow
through the source heat exchanger; (ii) closing the first expansion
device to cause refrigerant flow through the first expansion device
bypass circuit and the first check valve; (iii) controlling
respective openings in the 3-way valve to inactivate the reheat
circuit and to cause refrigerant flow to the second expansion
device; (iv) controlling an opening of the second expansion device
to cause refrigerant flow through the second expansion device, and
thereafter, the space heat exchanger, wherein an orientation of the
second check valve prohibits flow of refrigerant through the second
expansion device bypass circuit; and (v) controlling the reversing
valve to cause refrigerant flow from the discharge outlet port of
the compressor to the source heat exchanger and to return flow from
the space heat exchanger to the suction inlet port of the
compressor.
[0014] Operating the controller in the dehumidification mode may
include the steps of: (i) controlling an opening of the bypass
valve to modulate refrigerant flow through the source heat
exchanger and through the source heat exchanger bypass circuit;
(ii) closing the first expansion device to cause refrigerant flow
through the first expansion device bypass circuit and the first
check valve; (iii) controlling respective openings in the 3-way
valve to cause refrigerant flow from the second expansion device
bypass circuit to the reheat circuit, and thereafter, to the second
expansion device; (iv) controlling an opening of the second
expansion device to cause refrigerant flow through the second
expansion device, and thereafter, the space heat exchanger, wherein
an orientation of the second check valve prohibits flow of
refrigerant through the second expansion device bypass circuit; and
(v) controlling the reversing valve to cause refrigerant flow from
the discharge outlet port of the compressor to the source heat
exchanger and to return flow from the space heat exchanger to the
suction inlet port of the compressor. The method may include the
step of controlling an opening of a reheat bypass valve positioned
along the reheat circuit to modulate refrigerant flow through the
reheat heat exchanger.
[0015] Operating the controller in the heating mode may include the
steps of: (i) controlling the reversing valve to cause refrigerant
flow from the discharge outlet port of the compressor to the space
heat exchanger and to return flow from the source heat exchanger to
the suction inlet port of the compressor; (ii) closing the second
expansion device to cause refrigerant flow through the second
expansion device bypass circuit and the second check valve, and
thereafter, the reheat heat exchanger; (iii) controlling respective
openings in the 3-way valve to cause refrigerant flow in the reheat
circuit, and thereafter, to the first expansion device; (iv)
controlling an opening of the first expansion device to cause
refrigerant flow through the first expansion device, wherein an
orientation of the first check valve prohibits flow of refrigerant
through the first expansion device bypass circuit; and (v) closing
the bypass valve to cause refrigerant flow through the source heat
exchanger. The method may include the step of controlling an
opening of a reheat bypass valve positioned along the reheat
circuit to modulate refrigerant flow through the reheat heat
exchanger.
[0016] In another embodiment, a heat pump system for conditioning
air in a space is disclosed, comprising a heat pump loop comprising
a refrigerant circuit that fluidly interconnects: (1) a compressor
having a discharge outlet port and an inlet suction port; (2) a
source heat exchanger operable as either a condenser or an
evaporator; (3) a space heat exchanger operable as either an
evaporator or a condenser for cooling or heating the air in the
space; (4) an expansion device positioned between the source heat
exchanger and the space heat exchanger; (5) a reheat circuit
comprising a reheat heat exchanger to reheat the air when the
system is in a dehumidification mode, and operable to act as an
auxiliary condenser when the system is in a heating mode, wherein
the space heat exchanger and the reheat heat exchanger are
positioned in an air flow path for conditioning the air in the
space; (6) a reversing valve to alternately direct refrigerant flow
to one of the source heat exchanger and the space heat exchanger
and to alternately return flow from the other of the source heat
exchanger and the space heat exchanger to the suction inlet port of
the compressor; and (7) a 3-way valve positioned downstream of the
compressor and configured to selectively direct refrigerant flow to
the reversing valve and the reheat heat exchanger.
[0017] The compressor may be a variable capacity compressor. The
heat pump system may include a liquid pump associated with the
source heat exchanger and the pump may be a variable capacity pump.
The heat pump system may include a fan associated with the space
heat exchanger and the fan may be a variable airflow fan. The
expansion device may be a fixed orifice device, a mechanical valve,
or an electronic valve. The reheat circuit may include a reheat
bypass valve to modulate refrigerant flow through the reheat heat
exchanger. The reheat bypass valve may be bi-directional. The
reheat circuit may include a shutoff valve positioned downstream of
the reheat heat exchanger and upstream of the reversing valve.
[0018] The heat pump system may include a controller comprising a
processor and memory on which one or more software programs are
stored. The controller may be configured to control operation of
the reversing valve, the 3-way valve, the shutoff valve, the
expansion device, the compressor, the liquid pump for circulating
water or brine solution through the source heat exchanger, and the
fan for flowing air over the space heat exchanger and the reheat
heat exchanger.
[0019] To operate the system in a cooling mode, the controller may
be configured to: (a) control the 3-way valve and the shutoff valve
to inactivate the reheat circuit and to cause refrigerant flow from
the discharge port of the compressor to the 3-way valve, thereafter
the reversing valve, and thereafter the source heat exchanger; (b)
control an opening of the expansion device to cause refrigerant
flow from the source heat exchanger to the expansion device, and
thereafter the space heat exchanger; and (c) control the reversing
valve to cause refrigerant flow from the 3-way valve to the source
heat exchanger and to return flow from the space heat exchanger to
the suction inlet port of the compressor.
[0020] To operate the system in the dehumidification mode, the
controller may be configured to: (a) control the 3-way valve and
the shutoff valve to activate the reheat circuit and to cause
refrigerant flow from the discharge port of the compressor to the
3-way valve, thereafter the reheat heat exchanger, thereafter the
shutoff valve, thereafter, the reversing valve, and thereafter, the
source heat exchanger; (b) control an opening of the expansion
device to cause refrigerant flow from the source heat exchanger to
the expansion device, and thereafter the space heat exchanger; and
(c) control the reversing valve to cause refrigerant flow from the
reheat circuit to the source heat exchanger and to return flow from
the space heat exchanger to the suction inlet port of the
compressor. The controller may be configured to control an opening
of a reheat bypass valve positioned along the reheat circuit to
modulate refrigerant flow through the reheat heat exchanger
[0021] To operate the system in the heating mode, the controller
may be configured to: (a) control the 3-way valve and the shutoff
valve to activate the reheat circuit and to cause refrigerant flow
from the discharge port of the compressor to the 3-way valve,
thereafter the reheat heat exchanger, thereafter the shutoff valve,
thereafter, the reversing valve, and thereafter, the space heat
exchanger; (b) control an opening of the expansion device to cause
refrigerant flow from the space heat exchanger to the expansion
device, and thereafter the source heat exchanger; and (c) control
the reversing valve to cause refrigerant flow from the reheat
circuit to the space heat exchanger and to return flow from the
source heat exchanger to the suction inlet port of the compressor.
The controller may be configured to control an opening of a reheat
bypass valve positioned along the reheat circuit to modulate
refrigerant flow through the reheat heat exchanger.
[0022] In another embodiment, a heat pump system for conditioning
air in a space is disclosed comprising a heat pump loop comprising
a refrigerant circuit that fluidly interconnects: (1) a compressor
having a discharge outlet port and an inlet suction port; (2) a
source heat exchanger operable as either a condenser or an
evaporator; (3) a source heat exchanger bypass circuit comprising a
source heat exchanger bypass valve to modulate refrigerant flow
through the source heat exchanger; (4) a space heat exchanger
operable as either an evaporator or a condenser for cooling or
heating the air in the space; (5) a reversing valve positioned on
the discharge side of the compressor and configured to alternately
direct refrigerant flow from the discharge outlet port of the
compressor to one of the source heat exchanger and the space heat
exchanger and to alternately return flow from the other of the
source heat exchanger and the space heat exchanger to the suction
inlet port of the compressor; (6) a reheat heat exchanger to reheat
the air when the system is in a dehumidification mode, and operable
to act as an auxiliary condenser when the system is in a heating
mode and as an auxiliary evaporator when the system is in a cooling
mode, wherein the space heat exchanger and the reheat heat
exchanger are positioned in an air flow path for conditioning the
air in the space; (7) first and second expansion devices; and (8)
first and second expansion device bypass circuits configured to
allow refrigerant to bypass the first and second expansion devices,
respectively, the first and second expansion device bypass circuits
comprising first and second expansion device bypass valves,
respectively, where the first expansion device is positioned
between the source heat exchanger and the reheat heat exchanger and
the second expansion device is positioned between the reheat heat
exchanger and the space heat exchanger.
[0023] The compressor may be a variable capacity compressor. The
heat pump system may include a liquid pump associated with the
source heat exchanger and the pump is a variable capacity pump. The
heat pump system may include a fan associated with the space heat
exchanger and the fan may be a variable airflow fan. The second
expansion device bypass valve may be bi-directional. The second
expansion device bypass circuit may be positioned between the
reheat heat exchanger and the space heat exchanger. The first and
second expansion devices may be fixed orifice devices, mechanical
valves, or electronic valves.
[0024] The heat pump system may include a controller comprising a
processor and memory on which one or more software programs are
stored. The controller may be configured to control operation of
the reversing valve, the source heat exchanger bypass valve, the
first and second expansion devices, the first and second expansion
device bypass valves, the compressor, the liquid pump for
circulating water or brine solution through the source heat
exchanger, and the fan for flowing air over the space heat
exchanger and the reheat heat exchanger.
[0025] To operate the system in a cooling mode, the controller may
be configured to: (a) close the source heat exchanger bypass valve
to cause refrigerant flow through the source heat exchanger; (b)
close the first expansion device bypass valve to cause refrigerant
flow through the first expansion device and then through the reheat
heat exchanger; (c) close the second expansion device to cause
refrigerant flow through the second expansion device bypass circuit
and then through the space heat exchanger; and (d) control the
reversing valve to cause refrigerant flow from the discharge outlet
port of the compressor to the source heat exchanger and to return
flow from the space heat exchanger to the suction inlet port of the
compressor.
[0026] To operate the system in the dehumidification mode, the
controller may be configured to: (a) control an opening of the
source heat exchanger bypass valve to modulate refrigerant flow
through the source heat exchanger and through the source heat
exchanger bypass circuit; (b) close the first expansion device to
cause refrigerant flow through the first expansion device bypass
circuit and then through the reheat heat exchanger; (c) close the
second expansion device bypass valve to cause refrigerant flow
through the second expansion device; (d) control an opening of the
second expansion device to modulate refrigerant flow from the
reheat heat exchanger through the second expansion device, and
thereafter, the space heat exchanger; and (e) control the reversing
valve to cause refrigerant flow from the discharge outlet port of
the compressor to the source heat exchanger and to return flow from
the space heat exchanger to the suction inlet port of the
compressor.
[0027] To operate the system in the heating mode, the controller
may be configured to: (a) close the source heat exchanger bypass
valve to cause refrigerant flow through the source heat exchanger;
(b) close the first expansion device bypass valve to cause
refrigerant flow through the first expansion device and then
through the source heat exchanger; (c) close the second expansion
device to cause refrigerant flow through the second expansion
device bypass circuit and then through the reheat heat exchanger;
and (d) control the reversing valve to cause refrigerant flow from
the discharge outlet port of the compressor to the space heat
exchanger and to return flow from the source heat exchanger to the
suction inlet port of the compressor. The controller may be also
configured to control an opening of the second expansion device
bypass valve to modulate flow through the space heat exchanger and
the reheat heat exchanger.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a schematic showing an embodiment of a heat pump
system of the instant disclosure in a cooling mode.
[0029] FIG. 2 is a schematic showing the embodiment of FIG. 1 in a
dehumidification mode.
[0030] FIG. 3 is a schematic showing the embodiment of FIG. 1 in a
heating mode.
[0031] FIG. 4 is a schematic showing another embodiment of a heat
pump system of the instant disclosure in a cooling mode.
[0032] FIG. 5 is a schematic showing the embodiment of FIG. 4 in a
dehumidification mode.
[0033] FIG. 6 is a schematic showing the embodiment of FIG. 4 in a
heating mode.
[0034] FIG. 7 is a schematic showing another embodiment of a heat
pump system of the instant disclosure in a cooling mode.
[0035] FIG. 8 is a schematic showing the embodiment of FIG. 7 in a
dehumidification mode.
[0036] FIG. 9 is a schematic showing the embodiment of FIG. 7 in a
heating mode.
[0037] FIG. 10 is a schematic showing a controller and exemplary
heat pump components that may be controlled by the controller.
DETAILED DESCRIPTION
[0038] Although the figures and the instant disclosure describe one
or more embodiments of a heat pump system, one of ordinary skill in
the art would appreciate that the teachings of the instant
disclosure would not be limited to these embodiments. It should be
appreciated that any of the features of an embodiment discussed
with reference to the figures herein may be combined with or
substituted for features discussed in connection with other
embodiments in this disclosure.
[0039] The instant disclosure provides improved and flexible heat
pump operation when dehumidification of a conditioned space is
required. In one embodiment of a vapor compression circuit, a
reheat heat exchanger is positioned upstream of a 3-way valve with
respect to the refrigerant flow. In another embodiment, a reheat
heat exchanger is positioned downstream of the 3-way valve but
upstream of a source heat exchanger with respect to the refrigerant
flow. In yet another embodiment, a reheat heat exchanger is
positioned downstream of a source heat exchanger with respect to
the refrigerant flow.
[0040] All three of the foregoing embodiments provide operational
flexibility via a modulating, pulse width modulating (PWM) or rapid
cycle solenoid valve diverting at least a portion of the
refrigerant around the reheat heat exchanger in the
dehumidification mode of operation. Alternatively or additionally,
an ON-OFF 3-way valve and a bypass valve may be replaced by the
modulating, PWM or rapid cycle solenoid 3-way valve. A controller
comprising a processor coupled to memory on which one or more
software algorithms are stored may process and issue commands to
open, partially open, or close any of the valves disclosed herein.
Open or closed feedback loops may be employed to determine current
and desired valve positions.
[0041] All three of the embodiments may employ variable speed or
multi-speed refrigerant and/or source fluid pumps, fan and/or
blower motor, and compressor to control dehumidification capability
and head pressure. The controller may be configured to operate any
or all of these devices to provide the desired system performance.
In the heating mode, the reheat heat exchanger may act as an
auxiliary condenser or evaporator to enhance system performance and
avoid the "cold blow" effect. Any of the expansion valves disclosed
herein may be any type of expansion device, including a
thermostatic expansion valve, and can be electronic, mechanical,
electromechanical, or fixed orifice type. The charge migration or
condensation of refrigerant in the reheat heat exchanger can be
controlled by a charge compensator or a shutoff valve. The
potential oil accumulation in the reheat heat exchanger when the
reheat refrigeration circuit is inactive can be controlled by
periodically activating the reheat circuit for a short period of
time. In at least one of the embodiments described herein, a
portion of the existing space heat exchanger may act as a reheat
heat exchanger during the dehumidification mode of operation. All
of the embodiments described herein provide improved comfort level,
system performance, and system reliability.
[0042] Turning now to the drawings and to FIGS. 1-9 in particular,
there are shown various embodiments of a heat pump system
configured to provide dehumidification of a conditioned space when
required. For example, FIGS. 1-3 show heat pump system 10
configured in a cooling mode, a dehumidification mode, and a
heating mode, respectively. FIGS. 4-6 show heat pump system 60
configured in a cooling mode, a dehumidification mode, and a
heating mode, respectively. FIGS. 7-9 show heat pump system 110
configured in a cooling mode, a dehumidification mode, and a
heating mode, respectively. Systems 10,60,110 are designed for
conditioning the air in a predetermined space. As used herein, "air
conditioning" and related terms related to heating, cooling, or
dehumidifying the air, and to any combination of these.
[0043] In the embodiment of FIGS. 1-3, heat pump system 10 includes
a heat pump loop 16 comprising a reheat circuit 18. Heat pump
system 10 includes compressor 20; reversing valve 22; source heat
exchanger 24; source heat exchanger bypass circuit 26 comprising
bypass valve 28; expansion valve 30; expansion valve bypass circuit
32 comprising check valve 34; three-way valve 36; reheat circuit 18
comprising reheat bypass valve 38 and reheat heat exchanger 40;
expansion valve 42; expansion valve bypass circuit 44 comprising
check valve 46; and space heat exchanger 48. Compressor 20 includes
a suction inlet port 50 and a discharge outlet port 52. The heat
pump system 10 may include a fan 12 associated with the space heat
exchanger 48 and the fan 12 may be a variable airflow fan.
[0044] Referring to FIG. 1, heat pump system 10 is shown in a
cooling mode with reheat circuit 18 inactive. Compressed gaseous
refrigerant exiting the compressor 20 at discharge outlet port 52
is conveyed to the reversing valve 22 where the refrigerant is then
conveyed to the source heat exchanger 24 acting as a condenser. In
cooling mode, bypass valve 28 is closed, which causes source heat
exchanger bypass circuit 26 to be inactive. The capacity (e.g.
speed) of the liquid pump 14 circulating the fluid through heat
exchanger 24 may be adjusted to control heat rejected by the heat
exchanger 24 and system discharge pressure. Likewise, with
expansion valve 30 being closed, and with the orientation of check
valve 34 permitting flow therethrough, the expansion valve bypass
circuit 32 is configured to be active. Thus, all of the refrigerant
from the compressor discharge conduit passes through the source
heat exchanger 24 and the expansion valve bypass circuit 32, after
which the refrigerant is conveyed to three-way valve 36.
[0045] Three-way valve 36 is configured to direct the refrigerant
to expansion valve 42 rather than entering the reheat circuit 18.
With expansion valve bypass circuit 44 inactive due to the opposite
flow orientation of check valve 46, the refrigerant is directed to
the expansion valve 42 where the refrigerant is metered, expanded
and cooled before entering the space heat exchanger 48. Refrigerant
conveyed in the coil of the space heat exchanger 48, which acts as
an evaporator when system 10 is in cooling mode, absorbs heat from
air flowing over the coil of the space heat exchanger 48 thereby
cooling the air for conditioning a space. Refrigerant exiting the
space heat exchanger 48 is then conveyed to the reversing valve 22,
which directs the refrigerant back to the compressor 20 to start
the cycle over again. It should be noted that the coil in the
reheat heat exchanger 40 may be filled with subcooled liquid
refrigerant.
[0046] Referring to FIG. 2, system 10 is shown configured in a
dehumidification mode. In this mode, the flow of refrigerant
through heat pump loop 16 is the same as shown in FIG. 1 except the
source heat exchanger bypass circuit 26 may be active (i.e., bypass
valve 28 may be fully opened, partially opened, or fully closed to
obtain optimum refrigerant conditions at the inlet of the reheat
heat exchanger 40), the expansion valve bypass circuit 32 is active
(i.e., expansion valve 30 is closed), and the expansion valve
bypass circuit 44 is inactive (due to the opposite flow orientation
of check valve 46). In addition, rather than three-way valve 36
directing refrigerant to expansion valve 42, three-way valve 36
instead directs the refrigerant to reheat heat exchanger 40, which
is positioned downstream of the space heat exchanger 48 relative to
air flowing over the respective coils. Thus, air flowing over the
coil of the space heat exchanger 48 is cooled and dehumidified by
the space heat exchanger 48 and then the air is directed to flow
over the reheat heat exchanger 40 to add heat to the air to avoid
overcooling the air. Bypass valve 28 may be automatically
controlled to be fully opened, partially opened, or fully closed as
needed to control the refrigerant inlet condition(s) to reheat heat
exchanger 40. Bypass valve 28 may be automatically cycled open and
closed and/or controlled on and off with a PWM signal to modulate
the amount of refrigerant flowing through the source heat exchanger
24. The capacity (e.g. speed) of the liquid pump 14 circulating the
fluid through heat exchanger 24 may be adjusted to control heat
rejected by the heat exchanger 24 and system discharge
pressure.
[0047] If the three-way valve 36 is configured to be adjustable,
the three-way valve 36 may control the refrigerant mass flow rate
flowing through reheat circuit 18 to provide adjustable outlet air
temperature exiting from the coils of the space heat exchanger 48
and reheat heat exchanger 40 for distribution to the
air-conditioned space. If the three-way valve 36 is not adjustable,
reheat bypass valve 38 may be configured to cause some of the
refrigerant flow to bypass the reheat heat exchanger 40 to reduce
the mass flow rate entering the reheat heat exchanger 40. The
reheat bypass valve 38 may be automatically cycled opened and
closed and/or controlled on and off with a PWM signal to modulate
the amount of refrigerant flowing through the reheat heat exchanger
40.
[0048] Referring to FIG. 3, system 10 is shown configured in a
heating mode with added capacity for heating the conditioned air
using the reheat heat exchanger 40. In this mode, hot gaseous
refrigerant exiting the compressor 20 at discharge outlet port 52
is directed to reversing valve 22, which directs the refrigerant to
the space heat exchanger 48. Space heat exchanger 48 acts as a
condenser when system 10 is in heating mode. With a closed
expansion valve 42, refrigerant exiting the space heat exchanger 48
is directed to the active expansion valve bypass circuit 44 and
through check valve 46. The refrigerant is then conveyed to the
reheat heat exchanger 40. To heat a space, air flowing over space
heat exchanger 48 picks up heat from the space heat exchanger 48
before the air is directed to flow over the reheat heat exchanger
40 to pick up additional heat. Reheat heat exchanger 40 therefore
acts as an auxiliary condenser in this heating mode.
[0049] Refrigerant exiting the reheat heat exchanger is then
directed to three-way valve 36, which directs the flow to expansion
valve 30 while expansion valve bypass circuit 32 is inactive. The
expansion valve 30 expands the refrigerant thereby cooling the
refrigerant before entering the source heat exchanger 24 while
source heat exchanger bypass circuit 26 is inactive (i.e., bypass
valve 28 is closed). The source heat exchanger 24 acts as an
evaporator to fully evaporate the refrigerant before the
refrigerant is directed to the reversing valve 22, which directs
the refrigerant to the suction inlet port 50 of the compressor 20
to continue the cycle. With the reheat heat exchanger 40 acting as
an auxiliary condenser, system 10 may improve the subcooling and
consequently the capacity and efficiency of system 10 while in this
heating mode, as well as increase supply air temperature preventing
the "cold blow" effect. In cold climates, reheat heat exchanger 40
provides additional heating capacity to avoid auxiliary (e.g.
electric) heaters.
[0050] Referring to FIGS. 4-6, there is shown another embodiment of
a heat pump system configured in a cooling mode, a dehumidification
mode, and a heating mode, respectively. Heat pump system 60
includes heat pump loop 66 comprising reheat circuit 68. Heat pump
loop 66 includes compressor 70, reversing valve 72, source heat
exchanger 74, expansion valve 92, space heat exchanger 98, and
three-way valve 86. Reheat circuit 68 of heat pump loop 66 includes
reheat heat exchanger 90, reheat bypass valve 88, and shutoff valve
96. Compressor 70 includes suction inlet port 100 and discharge
outlet port 102. Three-way valve 86 is positioned downstream of the
compressor discharge outlet port 102 of compressor 70 and upstream
of reversing valve 72. The heat pump system 60 may include a fan 62
associated with the space heat exchanger 98 and the fan 62 may be a
variable airflow fan.
[0051] Unlike heat pump system 10, heat pump system 60 does not
require expansion valve bypass circuits. And although the reheat
heat exchanger is positioned downstream of the space heat exchanger
in terms of the direction of air flowing over the coils of these
two heat exchangers, the refrigerant connection conduits for the
reheat circuit 68 connect with the heat pump loop 66 downstream of
the compressor 70 and upstream of the reversing valve 72. Similarly
to the previous embodiment, the bypass around source heat exchanger
74 may be applied, but not shown for simplicity.
[0052] Referring FIG. 4, heat pump system 60 is shown configured in
a cooling mode with the reheat circuit 68 inactive. Hot gaseous
refrigerant exiting the discharge outlet port 102 of compressor 70
is directed by a conduit to the three-way valve 86, which directs
the gas to reversing valve 72, which in turn directs the gas to
source heat exchanger 74. Refrigerant exiting source heat exchanger
74 acting as a condenser is directed to expansion valve 92.
Refrigerant exiting the expansion valve 92 is directed to space
heat exchanger 98. Refrigerant exiting space heat exchanger 98
acting as an evaporator is directed to the reversing valve 72,
which in turn directs the gas back to the suction inlet port 100 of
compressor 70. Shutoff valve 96 in combination with proper control
of three-way valve 86 insures that hot gas from the compressor 70
does not enter reheat circuit 68 when heat pump system 10 is
operating in cooling mode. Refrigerant conveyed in the coil of the
space heat exchanger 98 absorbs heat from air flowing over the
space heat exchanger 98 thereby cooling the air for conditioning a
space.
[0053] Referring to FIG. 5, heat pump system 60 is shown configured
in a dehumidification mode. In this mode, reheat circuit 68 is
active. Hot gaseous refrigerant exiting compressor 70 at discharge
outlet port 102 is directed to three-way valve 86, which in turn
directs the refrigerant to reheat heat exchanger 90 positioned
downstream of space heat exchanger 98 such that air cooled after
flowing across the space heat exchanger 98 is then caused to flow
over the reheat heat exchanger 90 to pick up an heat, thereby
preventing overcooling the air distributed to the air-conditioned
space.
[0054] Refrigerant exiting reheat heat exchanger 90 is directed to
open shutoff valve 96. The refrigerant is then directed to
reversing valve 72, which directs the refrigerant to source heat
exchanger 74 to exchange heat with the source fluid. The
refrigerant is then conveyed to the expansion valve 92, which
expands and therefore causes the pressure and temperature reduction
of the refrigerant, before refrigerant enters space heat exchanger
98. Refrigerant exiting the space heat exchanger 98 acting as an
evaporator is then directed to the reversing valve 72, which in
turn directs the refrigerant back to the suction inlet port 100 of
compressor 70. Thus, air flowing over the space heat exchanger 98
is cooled by the space heat exchanger 98 and then the air is
directed to flow over the reheat heat exchanger 98 to add heat to
the air to prevent overcooling the air.
[0055] The three-way valve 86 may be adjustable as described above
to adjust the refrigerant mass flow rate provided to the reheat
circuit 68 for optimum supply air temperature that is distributed
to the air-conditioned space. Alternatively, as described above,
the three-way valve may not be adjustable. In that case, reheat
bypass valve 88 may be configured as a simple on-off valve. As
described above, reheat bypass valve 88, may be controlled via a
PWM algorithm that controls the mass flow rate of refrigerant
entering reheat heat exchanger 90 by cycling reheat bypass valve 88
open and closed according to the algorithm. The capacity (e.g.
speed) of the liquid pump 64 circulating the fluid through heat
exchanger 74 may be adjusted to control heat rejected by the heat
exchanger 74 and system discharge pressure.
[0056] Referring to FIG. 6, heat pump system 60 is shown configured
in a heating mode. In this mode, reheat circuit 68 is active (i.e.,
reheat bypass valve 88 is closed) and the reheat heat exchanger 90
acts as an additional condenser to supplement the air heating
capacity of space heat exchanger 98 to heat air flowing across the
space heat exchanger 98 and reheat heat exchanger 90.
[0057] In this mode, hot gaseous refrigerant exiting the discharge
outlet port 102 of compressor 70 is directed to three-way valve 86,
which in turn directs the refrigerant to reheat heat exchanger 90.
The refrigerant is then directed to open shutoff valve 96, after
which the refrigerant is directed to reversing valve 72. The
refrigerant is then conveyed to space heat exchanger 98, after
which the refrigerant is conveyed to the expansion valve 92. The
expanded refrigerant of reduced pressure and temperature after
passing through the expansion valve 92 is then conveyed to the
source heat exchanger 74, which acts as an evaporator. The
refrigerant discharged from the source heat exchanger 74 is
conveyed to the reversing valve 72, which directs the refrigerant
back to the suction inlet port 100 of compressor 70.
[0058] To heat a space, air flowing over the space heat exchanger
98 picks up heat from the space heat exchanger 98 before the air is
directed to flow over the reheat heat exchanger 90 to pick up
additional heat. Reheat heat exchanger 90 therefore acts as an
auxiliary condenser in this heating mode. The extra condenser
provided by reheat heat exchanger 90 helps to increase the heat
transfer to the air, increase the subcooling of the refrigerant,
and increase the capacity and efficiency of heat pump system 60, as
well as increase temperature of the air supplied to a conditioned
space therefore avoiding a "cold blow" effect. The capacity (e.g.
speed) of the liquid pump 64 circulating the fluid through heat
exchanger 74 may be adjusted to control heat rejected by the heat
exchanger 74 and system discharge pressure.
[0059] FIG. 7-9 shows another embodiment of a heat pump system. As
shown in the figures, heat pump system 110 includes compressor 120
comprising suction inlet port 150 and discharge outlet port 152,
reversing valve 122, source heat exchanger 124, source heat
exchanger bypass circuit 126 comprising bypass valve 128, expansion
valve 130, expansion valve bypass circuit 132 comprising bypass
valve 134, reheat heat exchanger 140, expansion valve 142,
expansion valve bypass circuit 144 comprising bypass valve 146, and
space heat exchanger 148. The heat pump system 110 may include a
fan 112 associated with the space heat exchanger 148 and the fan
112 may be a variable airflow fan.
[0060] Heat pump system 110 is schematically similar to heat pump
system 10, but instead of employing two different air coils, a
larger space coil is employed. In this embodiment, expansion valve
bypass circuit 144 and expansion valve 142 of heat pump system 110
are positioned between reheat heat exchanger 140 and space heat
exchanger 148 and therefore divide the larger space coil into two
parts. One part may be used as a reheat coil and the other part may
be used as a main space heating/cooling coil.
[0061] Referring to FIG. 7, heat pump system 110 is shown in a
cooling mode. Hot gaseous refrigerant exiting the discharge outlet
port 152 of compressor 120 is directed by a conduit to the
reversing valve 122, which in turn directs the refrigerant gas to
source heat exchanger 124. Refrigerant exiting source heat
exchanger 124 acting as a condenser is directed to expansion valve
130, which is configured to meter, expand and cool the refrigerant
before the refrigerant enters reheat heat exchanger 140, which is
the first stage of the two-stage space heat exchanger 149. Upon
exiting the reheat heat exchanger 140 acting as an evaporator, the
refrigerant bypasses a closed expansion valve 142. The refrigerant
instead is conveyed through expansion valve bypass circuit 144 and
bypass valve 146 to then flow through the space heat exchanger 148,
which is the second stage of the two-stage space heat exchanger
149. In cooling mode, space heat exchanger 148 acts as an extension
of the evaporator provided by reheat heat exchanger 140 to increase
the size of the evaporator. Thus, refrigerant conveyed in the space
heat exchanger 148 and the reheat heat exchanger 140 absorbs heat
from air flowing over these coils to cool the air for conditioning
a space.
[0062] For control purposes, bypass valve 146 may be automatically
cycled open and closed and/or controlled on and off with a PWM
signal. Refrigerant exiting the space heat exchanger 148 is
conveyed to reversing valve 122, which directs the refrigerant to
suction inlet port 150 of compressor 120.
[0063] Referring to FIG. 8, heat pump system 110 is shown in a
dehumidification mode. In this mode, hot gaseous refrigerant
exiting the discharge outlet port 152 of compressor 120 is directed
to the reversing valve 122, which in turn directs the refrigerant
to source heat exchanger 124 acting as a condenser. As shown in the
figure, source heat exchanger bypass circuit 126 is active via
bypass valve 128, and the expansion valve bypass circuit 132 is
active via bypass valve 134. Consequently, some, none, or all of
the heated refrigerant may be permitted to flow through the source
heat exchanger 124, and some, none, or all of the refrigerant may
be permitted to flow through the source heat exchanger bypass
circuit 126 to obtain optimum refrigerant conditions at the inlet
of reheat heat exchanger 140. Bypass valve 128 controls the amount
of refrigerant mass flow that traverses through the source heat
exchanger bypass circuit 126, which affects the amount of
refrigerant mass flow traversing through the source heat exchanger
124. Bypass valve 128 may be automatically cycled open and closed
and/or controlled on and off with a PWM signal to modulate the
amount of refrigerant flowing through the source heat exchanger
bypass circuit 126. The capacity (e.g. speed) of the liquid pump
114 circulating the fluid through heat exchanger 124 may be
adjusted to control heat rejected by the heat exchanger 124 and
system discharge pressure.
[0064] Refrigerant exiting the source heat exchanger 124 acting as
a condenser and source heat exchanger bypass circuit 126 are
combined and then directed to expansion valve bypass circuit 132.
In dehumidification mode, none of the refrigerant enters the
expansion valve 130.
[0065] Refrigerant exiting the expansion bypass circuit 132 is
directed to reheat heat exchanger 140. Upon exiting reheat heat
exchanger 140 and with bypass valve 146 being closed, subcooled
refrigerant is directed to expansion valve 142, which meters,
expands and cools the refrigerant before the refrigerant enters
space heat exchanger 148 acting as an evaporator. Upon leaving
space heat exchanger 148, the refrigerant is directed to the
reversing valve 122, which then directs the flow back to the
suction inlet port 150 of compressor 120. Thus, air flowing over
the space heat exchanger 148 is cooled by the space heat exchanger
148 and then the air is directed to flow over the reheat heat
exchanger 140 to add heat to prevent overcooling the air.
[0066] Referring to FIG. 9, heat pump system 110 is configured in a
heating mode. For example, hot gaseous refrigerant leaving the
discharge outlet port 152 of compressor 120 is directed to
reversing valve 122, which directs the refrigerant to space heat
exchanger 148 acting as a condenser. Refrigerant exiting space heat
exchanger 148 is directed to bypass valve 146, which in turn
directs the refrigerant to reheat heat exchanger 140. The expansion
valve 142 is not needed for heating mode. To heat a space, air
flowing over the coil of space heat exchanger 148 picks up heat
from the space heat exchanger 148 before the air is directed to
flow over the reheat heat exchanger 140 to pick up additional heat.
Reheat heat exchanger 140 therefore acts as an auxiliary condenser
in this heating mode.
[0067] Refrigerant leaving reheat heat exchanger 140 is directed to
expansion valve 130. Expansion valve bypass circuit 132 and source
heat exchanger bypass circuit 126 are not active (i.e., bypass
valves 128,134 are closed) when heat pump system 110 is configured
in the heating mode. Refrigerant leaving the expansion valve 130 is
directed to source heat exchanger 124 acting as an evaporator to
exchange heat with the source fluid. Refrigerant leaving source
heat exchanger 124 is then directed the reversing valve 122, which
directs the refrigerant back to the suction inlet port 150 of
compressor 120. The extra condenser provided by reheat heat
exchanger 140 helps to increase the heat transfer to the air,
increase the subcooling of the refrigerant, and increase the
capacity and efficiency of heat pump system 110, as well as
increase temperature of the air supplied to a conditioned space
therefore avoiding a "cold blow" effect. The capacity (e.g. speed)
of the liquid pump 114 circulating the fluid through heat exchanger
124 may be adjusted to control heat rejected by the heat exchanger
124 and system discharge pressure.
[0068] Heat pump loops 16,66,116 include a conduit through which
refrigerant flows and which fluidly connects the components of heat
pump systems 10,60,110 to one another. Compressors 20,70,120 may
each be a variable capacity compressor, such as a variable speed
compressor, a compressor with an integral pulse-width modulation
option, or a compressor incorporating various unloading options.
These types of compressors allow for better control of the
operating conditions and management of the thermal load on the heat
pump loops 16,66,116.
[0069] Reversing valves 22,72,122 are positioned along the conduit
on the discharge side of compressors 20,70,120 and are configured
to selectively operate the heat pump loops 16,66,116 in a cooling
mode, a dehumidification mode, and a heating mode by controlling
the direction of refrigerant flowing in the heat pump loops
16,66,116.
[0070] Source heat exchangers 24,74,124 may each be a
refrigerant-to-water, refrigerant-to-brine, or refrigerant-to-air
heat exchanger and is not limited to any particular heat exchanger
type or configuration. Source heat exchangers 24,74,124 are fluidly
connected to a source 15,65,115, and the fluid, usually but not
necessarily water, is circulated by pumps 14,64,114. Pumps
14,64,114 may be a variable capacity pump (e.g. a variable speed
pump, a pump controlled by PWM signal, a cycling ON/OFF pump, a
pump with a bypass circuit or other means of unloading) for a more
efficient operation and better system control. Similarly, space
heat exchangers 48,98,148 are not limited to any particular heat
exchanger type or configuration.
[0071] Expansion valves 30,42,92,130,142 may each be an electronic
expansion valve, a mechanical expansion valve, a
fixed-orifice/capillary tube/accurator, or any combination of the
these. These valves may have bi-directional functionality or may be
replaced by a pair of uni-directional expansion devices coupled
with the associated bypass check valves to provide refrigerant
rerouting when the flow changes direction throughout the
refrigerant cycle between cooling and heating modes of
operation.
[0072] Valves 28,38,88,96,128,146 may each be electronically
controllable, mechanically and/or electromechanically actuated
valves, and may have bi-directional flow functionality.
[0073] Referring to FIG. 10, heat pump systems 10,60,110 may
include controller 78 comprising processor 80 and memory 82 on
which one or more software programs are stored. The controller 78
may be configured to control operation of the check valves 34,46,
the shut off valve 96, the reversing valves 22,72,122, the bypass
valves 28,38,88,128,134,146, the 3-way valves 36,86, the first and
second expansion devices 30,42,92,130,142, the compressors
20,70,120, the liquid pumps 14,64,114 for circulating water or
brine solution through the source heat exchangers 24,74,124, the
fans 12,62,112 for flowing air over the space heat exchangers
48,98,148, and the reheat heat exchangers 40,90,140.
[0074] While specific embodiments have been described in detail, it
will be appreciated by those skilled in the art that various
modifications and alternatives to those details could be developed
in light of the overall teachings of the disclosure. Accordingly,
the disclosure herein is meant to be illustrative only and not
limiting as to its scope and should be given the full breadth of
the appended claims and any equivalents thereof.
* * * * *