U.S. patent application number 13/920958 was filed with the patent office on 2013-12-26 for refrigeration system with pressure-balanced heat reclaim.
The applicant listed for this patent is Hill Phoenix, Inc.. Invention is credited to J. Scott Martin, Victor N. Votary.
Application Number | 20130340455 13/920958 |
Document ID | / |
Family ID | 49773253 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130340455 |
Kind Code |
A1 |
Martin; J. Scott ; et
al. |
December 26, 2013 |
REFRIGERATION SYSTEM WITH PRESSURE-BALANCED HEAT RECLAIM
Abstract
A refrigeration system with pressure-balanced heat reclaim
includes at least one compressor configured to discharge a
compressed refrigerant. A heat reclaim branch has a first end
configured to receive at least a first portion of the compressed
refrigerant and a second end, the heat reclaim branch also has a
first refrigerant pressure drop. A condensing branch has a first
end configured to receive at least a second portion of the
compressed refrigerant and a second end, the second end of the
condensing branch is fluidly coupled to the second end of the heat
reclaim branch, and the condensing branch has a second refrigerant
pressure drop. A pressure regulation device is disposed on one of
the heat reclaim branch and the condensing branch and substantially
equalizes the first refrigerant pressure drop and the second
refrigerant pressure drop.
Inventors: |
Martin; J. Scott; (Conyers,
GA) ; Votary; Victor N.; (Proton Station,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hill Phoenix, Inc. |
Conyers |
GA |
US |
|
|
Family ID: |
49773253 |
Appl. No.: |
13/920958 |
Filed: |
June 18, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61663141 |
Jun 22, 2012 |
|
|
|
Current U.S.
Class: |
62/126 ;
62/498 |
Current CPC
Class: |
F25B 6/02 20130101; F25B
29/003 20130101; F25B 2400/22 20130101; F25B 41/04 20130101 |
Class at
Publication: |
62/126 ;
62/498 |
International
Class: |
F25B 41/04 20060101
F25B041/04 |
Claims
1. A refrigeration system for circulating a refrigerant with
pressure-balanced heat reclaim, comprising: at least one
temperature-controlled storage device; at least one compressor
configured to draw the refrigerant from the temperature-controlled
storage device and to discharge a hot compressed refrigerant to a
discharge line; a heat reclaim branch having a first end fluidly
coupled to the discharge line and a second end; a heat reclaim heat
exchanger disposed between the first end and the second end of the
heat reclaim branch and configured to transfer heat from the hot
compressed refrigerant to one or more heating loads; a condensing
branch having a first end fluidly coupled to the discharge line and
a second end, the second end of the condensing branch being fluidly
coupled to the second end of the heat reclaim branch; a condenser
disposed between the first end and the second end of the condensing
branch; a pressure regulation device disposed between the heat
reclaim heat exchanger and the second end of the heat reclaim
branch; and wherein the pressure regulation device is operable to
substantially balance a refrigerant pressure in the heat reclaim
branch downstream of the pressure regulation device with a
refrigerant pressure in the condensing branch downstream of the
condenser.
2. The system of claim 1, wherein the condenser is an air-cooled
condenser and has a plurality of separate sections for flow of the
hot compressed refrigerant through the condenser.
3. The system of claim 2, further comprising a heat reclaim valve
disposed between the first end of the heat reclaim portion and the
heat reclaim heat exchanger, the heat reclaim valve operable to
divert a first portion of the hot compressed refrigerant to the
heat reclaim heat exchanger and away from the condenser.
4. The system of claim 3, further comprising a check valve disposed
on an outlet of each of the sections of the condenser.
5. The system of claim 4, wherein the pressure regulation device is
operable to avoid a backpressure condition downstream of the heat
exchanger, where the backpressure condition maintains the check
valves in a closed position and prevents flow of the refrigerant
through the circuits of the condenser.
6. The device of claim 5, further comprising a condenser inlet
valve disposed on an inlet to each section of the condenser.
7. The device of claim 6, further comprising a controller operable
to regulate a position of the heat reclaim valve, the condenser
inlet valves, and the pressure regulation device.
8. The device of claim 6, further comprising a bypass valve
arranged in parallel with a condenser inlet valve, the bypass valve
configured to allow the hot compressed refrigerant to bypass the
condenser inlet valve and enter the condenser.
9. The device of claim 8, wherein the bypass valve is configured to
allow the hot compressed refrigerant to bypass the condenser inlet
valve in response to a pressure of the hot compressed refrigerant
in the discharge line exceeding a threshold pressure.
10. A refrigeration system with pressure-balanced heat reclaim,
comprising: at least one compressor configured to discharge a
compressed refrigerant; a heat reclaim branch having a first end
configured to receive at least a first portion of the compressed
refrigerant and a second end; a heat reclaim valve and a heat
reclaim heat exchanger disposed between the first end and the
second end of the heat reclaim branch, the heat reclaim heat
exchanger configured to transfer heat from the compressed
refrigerant to one or more heating loads; a condensing branch
having a first end configured to receive at least a second portion
of the compressed refrigerant and a second end, the second end of
the condensing branch being fluidly coupled to the second end of
the heat reclaim branch; a condenser and at least one condenser
inlet valve disposed between the first end and the second end of
the condensing branch; a pressure regulation device disposed
between the heat reclaim heat exchanger and the second end of the
heat reclaim branch; and a controller configured to send a first
output signal to position the heat reclaim valve, and a second
output signal to position the condenser inlet valve, and a third
output signal to position the pressure regulation device to
substantially balance a first refrigerant pressure in the heat
reclaim branch downstream of the pressure regulation device with a
second refrigerant pressure in the condensing branch downstream of
the condenser.
11. The device of claim 10, wherein the heat reclaim branch
comprises a first refrigerant pressure drop and the condensing
branch comprises a second refrigerant pressure drop, the second
refrigerant pressure drop being different from the first
refrigerant pressure drop.
12. The device of claim 11, wherein the controller regulates a
position of the pressure regulation device so that the first
refrigerant pressure drop is substantially equal to the second
refrigerant pressure drop.
13. A refrigeration system with pressure-balanced heat reclaim,
comprising: at least one compressor configured to discharge a
compressed refrigerant; a heat reclaim branch having a first end
configured to receive at least a first portion of the compressed
refrigerant and a second end, the heat reclaim branch having a
first refrigerant pressure drop; a condensing branch having a first
end configured to receive at least a second portion of the
compressed refrigerant and a second end, the second end of the
condensing branch being fluidly coupled to the second end of the
heat reclaim branch, the condensing branch having a second
refrigerant pressure drop; and a pressure regulation device
disposed on one of the heat reclaim branch and the condensing
branch and configured to substantially equalize the first
refrigerant pressure drop and the second refrigerant pressure
drop.
14. The system of claim 13, further comprising a heat reclaim valve
and a heat reclaim heat exchanger disposed between the first end
and the second end of the heat reclaim branch, the heat reclaim
heat exchanger configured to transfer heat from the compressed
refrigerant to one or more heating loads.
15. The system of claim 14, further comprising a condenser and at
least one condenser inlet valve disposed between the first end and
the second end of the condensing branch.
16. The device of claim 15, further comprising a bypass valve
arranged in parallel with a condenser inlet valve, the bypass valve
configured to allow the compressed refrigerant discharged by the at
least one compressor to bypass the condenser inlet valve and enter
the condenser.
17. The device of claim 16, wherein the bypass valve is configured
to allow the compressed refrigerant to bypass the condenser inlet
valve in response to a pressure of the compressed refrigerant
discharged by the at least one compressor exceeding a threshold
pressure.
18. The system of claim 16 further comprising a controller
configured to send a first output signal to position the heat
reclaim valve, and a second output signal to position the condenser
inlet valve, and a third output signal to position the pressure
regulation device to substantially balance a first refrigerant
pressure in the heat reclaim branch downstream of the pressure
regulation device with a second refrigerant pressure in the
condensing branch downstream of the condenser.
19. The system of claim 18, further comprising at least one check
valve disposed on an outlet of the condenser.
20. The system of claim 19, wherein the pressure regulation device
is operable to avoid a backpressure condition downstream of the
heat reclaim heat exchanger, where the backpressure condition
maintains the check valve in a closed position and prevents flow of
the refrigerant through the condenser.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to U.S.
Provisional Patent Application No. 61/663,141, which was filed on
Jun. 22, 2012, the complete disclosure of which is incorporated by
reference herein.
FIELD
[0002] The present disclosure relates generally to the field of
refrigeration systems. The present disclosure relates more
particularly to refrigeration systems having heat reclaim that uses
heat from the compressed refrigerant to provide heating to one or
more heat loads through a heat reclaim heat exchanger. The present
disclosure relates more particularly still to a refrigeration
system having a pressure regulator that substantially balances the
refrigerant pressures between a condenser branch of the system
having a condenser, and a heat reclaim branch of the system having
the heat reclaim heat exchanger, during modes of system operation
where refrigerant is directed through both branches.
BACKGROUND
[0003] This section is intended to provide a background or context
to the invention recited in the claims. The description herein may
include concepts that could be pursued, but are not necessarily
ones that have been previously conceived or pursued. Therefore,
unless otherwise indicated herein, what is described in this
section is not prior art to the description and claims in this
application and is not admitted to be prior art by inclusion in
this section.
[0004] It is generally known to provide a refrigeration system for
use with one or more temperature controlled storage devices such as
a refrigerator, freezer, refrigerated merchandiser, display case,
etc., that may be used in commercial, institutional, and
residential applications for storing or displaying refrigerated or
frozen objects. For example, it is known to provide a refrigeration
system having a refrigerant for direct expansion to provide cooling
to a heat exchanger in the temperature-controlled storage devices
such as an evaporator or chiller. It is also generally known to use
waste heat from a compressed refrigerant as a source of heat for
nearby heating loads. It would be desirable to provide improved
operation and performance of a refrigeration system having both a
condensing branch with a condenser for condensing the compressed
refrigerant and a heat reclaim branch having a heat reclaim heat
exchanger for condensing the compressed refrigerant while using the
refrigerant as a heat source for heating loads.
SUMMARY
[0005] One embodiment of the disclosure relates to a refrigeration
system with pressure-balanced heat reclaim and includes at least
one compressor configured to discharge a compressed refrigerant. A
heat reclaim branch has a first end configured to receive at least
a first portion of the compressed refrigerant and a second end, the
heat reclaim branch also has a first refrigerant pressure drop. A
condensing branch has a first end configured to receive at least a
second portion of the compressed refrigerant and a second end, the
second end of the condensing branch is fluidly coupled to the
second end of the heat reclaim branch, and the condensing branch
has a second refrigerant pressure drop. A pressure regulation
device is disposed on one of the heat reclaim branch and the
condensing branch and substantially equalizes the first refrigerant
pressure drop and the second refrigerant pressure drop.
[0006] Another embodiment of the disclosure relates to
refrigeration system with pressure-balanced heat reclaim and
includes at least one compressor configured to discharge a
compressed refrigerant. A heat reclaim branch has a first end
configured to receive at least a first portion of the compressed
refrigerant and a second end. A heat reclaim valve and a heat
reclaim heat exchanger are disposed between the first end and the
second end of the heat reclaim branch, and the heat reclaim heat
exchanger transfers heat from the compressed refrigerant to one or
more heating loads. A condensing branch has a first end configured
to receive at least a second portion of the compressed refrigerant
and a second end, the second end of the condensing branch is
fluidly coupled to the second end of the heat reclaim branch. A
condenser and at least one condenser inlet valve are disposed
between the first end and the second end of the condensing branch.
A pressure regulation device is disposed between the heat reclaim
heat exchanger and the second end of the heat reclaim branch, and a
controller sends a first output signal to position the heat reclaim
valve, and a second output signal to position the condenser inlet
valve, and a third output signal to position the pressure
regulation device to substantially balance a first refrigerant
pressure in the heat reclaim branch downstream of the pressure
regulation device with a second refrigerant pressure in the
condensing branch downstream of the condenser.
[0007] Yet another embodiment of the disclosure relates to a
refrigeration system for circulating a refrigerant with
pressure-balanced heat reclaim and includes at least one
temperature-controlled storage device. At least one compressor
draws the refrigerant from the temperature-controlled storage
device and discharges a hot compressed refrigerant to a discharge
line. A heat reclaim branch has a first end fluidly coupled to the
discharge line and a second end. A heat reclaim heat exchanger is
disposed between the first end and the second end of the heat
reclaim branch and transfers heat from the hot compressed
refrigerant to one or more heating loads. A condensing branch has a
first end fluidly coupled to the discharge line and a second end
fluidly coupled to the second end of the heat reclaim branch. A
condenser is disposed between the first end and the second end of
the condensing branch. A pressure regulation device is disposed
between the heat reclaim heat exchanger and the second end of the
heat reclaim branch and is operable to substantially balance a
refrigerant pressure in the heat reclaim branch downstream of the
pressure regulation device with a refrigerant pressure in the
condensing branch downstream of the condenser.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The disclosure will become more fully understood from the
following detailed description, taken in conjunction with the
accompanying figures, wherein like reference numerals refer to like
elements, in which:
[0009] FIG. 1 is a schematic diagram of a refrigeration system
having a condensing branch with a condenser for condensing the
compressed refrigerant and a heat reclaim branch having a heat
reclaim heat exchanger for using the compressed refrigerant as a
heat source for heating loads, according to an exemplary
embodiment.
[0010] FIG. 2 is a block diagram of a controller for operating the
refrigeration system of FIG. 1 in a condensing operating mode, a
heat reclaim operating mode, and a combined operating mode, and for
balancing pressure drops associated with the condensing branch and
the heat reclaim branch, according to an exemplary embodiment.
[0011] FIG. 3 is a flowchart of a process for switching between the
condensing operating mode, the heat reclaim operating mode, and the
combined operating mode, according to an exemplary embodiment.
DETAILED DESCRIPTION
[0012] Referring generally to the FIGURES, systems and methods for
balancing pressure in a heat reclaim refrigeration system are
shown. The systems and methods described herein may be used to
equalize the pressure drops associated with refrigerant flow
through a condensing branch and a parallel heat reclaim branch of
the heat reclaim refrigeration system. A pressure regulation device
positioned along at least one of the condensing branch and the heat
reclaim branch is used to effectuate the pressure balance.
Advantageously, balancing the pressure drops associated with the
heat reclaim branch and the condensing branch may facilitate proper
operation of the heat reclaim refrigeration system by preventing
the refrigerant from backing up or ceasing to flow through one or
more of the heat reclaim branch and the condensing branch.
[0013] Referring now to FIG. 1, a heat reclaim refrigeration system
10 is shown, according to an exemplary embodiment. Refrigeration
system 10 may be used to circulate a refrigerant through one or
more temperature controlled storage devices 20 (e.g. refrigerated
cases, freezers, etc.) to provide cooling for the
temperature-controlled storage devices 20. In some embodiments,
refrigeration system 10 is a vapor compression refrigeration
system.
[0014] Refrigeration system 10 is shown to include expansion
devices 22, temperature-controlled storage devices 20, and
compressors 26. Expansion devices 22 may be electronic expansion
valves or other similar expansion valves which cause the
refrigerant to expand to a low pressure, low temperature state. The
expanded refrigerant is provided through temperature-controlled
storage devices 20 (e.g., evaporators of a vapor compression
refrigeration system) for removing heat from temperature-controlled
storage devices 20. Compressors 26 draw the refrigerant from
temperature-controlled storage devices 20 and compress the
refrigerant to a high temperature and high pressure compressed
refrigerant gas. Compressors 26 discharge the hot compressed gas to
a discharge line 28 for circulation through refrigeration system
10.
[0015] Still referring to FIG. 1, refrigeration system 10 is shown
to include condensing branch 30 and a heat reclaim branch 50.
Condensing branch 30 and heat reclaim branch 50 may be arranged in
parallel such that the refrigerant from discharge line 28 can flow
independently through either condensing branch 30, or heat reclaim
branch 50 (e.g., without flowing through the other), or through
both condensing branch 30 and heat reclaim branch 50 in
parallel.
[0016] Condensing branch 30 is shown to include a condenser 32 for
cooling and/or condensing the compressed refrigerant. In some
embodiments, condenser 32 is an air cooled condenser. Condenser 32
may be a "split condenser" having one or more sections that operate
independently (e.g., in parallel) to provide cooling for the
compressed refrigerant. For example, condenser 32 is shown to
include two sections 34 and 36 having a 25% capacity and a section
38 having a 50% capacity relative to the total capacity of
condenser 32. Sections 34-38 may be selectively utilized by
operation of condenser inlet valves 40-42. For example, condenser
inlet valve 40 may be operated (e.g., opened or closed) to control
the flow of the compressed refrigerant through 50% section 38.
Similarly, condenser inlet valves 41 and 42 may by operated to
control the flow of the compressed refrigerant through 25% sections
36 and 34 respectively. Condenser inlet valves 40-42 may be
solenoid valves operated by a signal from a controller (e.g.,
controller 70 described in greater detail with reference to FIG.
2).
[0017] Condensing branch 30 is shown to further include a gas
bypass valve 46. Gas bypass valve 46 may be a mechanical valve
configured to open when the pressure upstream of valve 46 exceeds a
threshold pressure. Gas bypass valve 46 may allow the compressed
refrigerant to bypass condenser inlet valve 42 and flow through 25%
section 34 regardless of the position of condenser inlet valve 42.
In some embodiments, gas bypass valve is an "open on rise pressure"
mechanical valve configured to receive a pressure signal from
pressure sensor 80. Pressure sensor 80 may be positioned along
refrigerant line 28, downstream of compressors 26. Gas bypass valve
46 may be configured to open when the pressure measured by pressure
sensor 80 exceeds a predetermined value. In some embodiments, the
predetermined value may be representative of a safe operating
pressure necessary to provide a maximum amount of heat to heat
reclaim branch 50. Advantageously, gas bypass value 46 may allow
excess refrigerant gas to be routed through condenser section 34
(e.g., to provide additional cooling, to alleviate excess pressure,
etc.) while avoiding excessive cycling of condenser inlet valve
42.
[0018] Condensing branch 30 is shown to further include condenser
outlet valves 47, 48, and 49. Condenser outlet valves 47-49 may be
one-way valves (e.g. check valves) intended to prevent reverse flow
of refrigerant through condenser 32. For example, condenser outlet
valve 47 may prevent refrigerant from flowing backwards from
refrigerant line 44 into 50% section 38. Similarly, condenser
outlet valves 48 and 49 may prevent refrigerant from flowing
backwards from refrigerant line 44 into 25% sections 36 and 34
respectively.
[0019] Still referring to FIG. 1, refrigeration system 10 is shown
to include a heat reclaim branch 50. Heat reclaim branch 50 may
include one or more heat reclaim heat exchangers for using the
compressed refrigerant as a heat source for heating loads 54. For
example, heat reclaim branch 50 is shown to include a first heat
reclaim heat exchanger 52 and a second heat reclaim heat exchanger
152. Heat reclaim heat exchangers 52 and 152 may be arranged in
parallel such that either of heat reclaim heat exchangers 52, 152
can be used independently (e.g., without using the other). Heat
reclaim heat exchangers 52 and 152 may be selectively utilized by
operating (e.g., opening and closing) heat reclaim valves 56 and
156 respectively. Heat reclaim valves 56 and 156 may solenoid
valves (e.g., operated by a signal from controller 70) to
selectively direct refrigerant through first heat reclaim heat
exchanged 52 and/or second heat reclaim heat exchanger 152.
[0020] Heat reclaim branch 50 is shown to further include a reheat
heat exchange fluid pump 55 for circulating a separate fluid (e.g.
glycol, water/glycol mixture, etc.) from the loads 54 through heat
reclaim heat exchangers 52, 152. Valves 57 and 157 may be arranged
in series with heat reclaim heat exchangers 52 and 152 respectively
for controlling the flow rate of the separate fluid through heat
reclaim heat exchangers 52, 152. Valves 57 and 157 may be
selectively opened and closed via a control signal from controller
70.
[0021] Although only one heat reclaim branch with two heat reclaim
heat exchangers are shown for clarity and simplicity, additional
heat reclaim heat exchangers and/or heat reclaim branches may be
included and are within the scope of this disclosure. According to
other alternative embodiments, the refrigeration system may be a
cascade refrigeration system having a low temperature subsystem and
a medium temperature subsystem, where each of the low and medium
temperature subsystems may each include one or more heat reclaim
heat exchangers and/or heat reclaim branches. All such variations
are intended to be within the scope of this disclosure.
[0022] Still referring to FIG. 1, refrigeration system 10 is shown
to include a controller 70. Controller 70 may be programmed to
operate refrigeration system 10 in several modes of operation. For
example, controller 70 may be configured to operate refrigeration
system 10 in a total heat reclaim mode, a total condensing mode,
and/or a combined heat reclaim/condensing mode. In some
embodiments, the mode of operation with which controller 70
operates depends upon the demand of the heating and cooling loads,
seasonal/geographical ambient temperature conditions, and/or other
factors affecting the condensation of the compressed refrigerant in
condensing branch 30 or heat reclaim branch 50. Controller 70 and
the various modes of operation used by controller 70 are described
in greater detail with reference to FIG. 2.
[0023] Refrigeration system 10 is shown to include a plurality of
sensors 72, 74, 76, and 78. Sensors 72-78 may be temperature
sensors, pressure sensors, flow rate sensors, enthalpy sensors, or
any combination thereof. Sensors 72-78 may provide data signals to
controller 70 indicating the values of one or more variables
measured by sensors 72-78. For example, sensor 72 may measure a
return temperature of a heat transfer fluid from heating loads 54.
The temperature measured by sensor 72 may indicate a demand level
from heating loads 54. Sensor 74 may measure the temperature and/or
pressure of the refrigerant at the outlet of heat reclaim heat
exchangers 52 and 152. The temperature and/or pressure measured by
sensor 74 may indicate the extent to which the refrigerant has been
condensed in heat reclaim heat exchangers 52 and 152. Sensor 76 may
include one or more sensors configured to measure the temperature
and/or pressure of the refrigerant at the outlet of condenser
sections 34, 36, and/or 38. The temperature and/or pressure
measured by sensor 76 may indicate the extent to which the
refrigerant has been condensed in condenser 32. In some
embodiments, sensor 76 measures a pressure of the refrigerant
within a fluid conduit 44 through which the refrigerant exits
condensing branch 30. Sensor 78 may measure a pressure of the
refrigerant in a fluid conduit 58 downstream of heat reclaim branch
50. In some embodiments, sensor 78 measures a fluid pressure
downstream of pressure regulation device 60.
[0024] Pressure regulation device 60 may be a pressure regulator, a
pressure regulation valve, a pressure control valve, or other
device for regulating the pressure upstream of pressure regulation
device 60 (e.g., measured by sensor 74) or downstream of pressure
regulation device 60 (e.g., measured by sensor 78). Pressure
regulation device 60 may receive a control signal from controller
70. Advantageously, pressure regulation device 60 may be operated
(e.g., by controller 70) to equalize or substantially equalize the
pressure in fluid conduits 44 and 58. In other words, controller 70
regulates a position of the pressure regulation device 60 so that
the refrigerant pressure drop in the heat reclaim branch 50 is
substantially equal to the refrigerant pressure drop in the
condensing branch 30.
[0025] Referring now to FIG. 2, a block diagram of controller 70 is
shown, according to an exemplary embodiment. Controller 70 is shown
to include a communications interface 88 and a processing circuit
90. Communications interface 88 may include wired or wireless
interfaces (e.g., jacks, antennas, transmitters, receivers,
transceivers, wire terminals, Ethernet ports, WiFi transceivers,
etc.) for conducting data communications with local or remote
devices or systems. Communications interface 88 may be used to
communicate with a wireless networking device (e.g., a wireless
router, wireless-enabled computer, laptop, tablet, cell tower,
etc.) and/or a wired networking device (e.g., via an Ethernet
cable, a SATA cable, USB cable, or other physical data
connection).
[0026] Communications interface 88 may allow controller 70 to
receive data signals from the sensory devices of refrigeration
system 10 (e.g., sensors 72-78) and provide control signals to the
control devices of refrigeration system 10 (e.g., valves 40-42,
valves 56 and 156, valves 57 and 157, compressors 26, reheat heat
exchange heat pump 55, pressure regulation device 60, etc.) for
controlling the flow of refrigerant and heat transfer within
refrigeration system 10. For example, controller 70 may provide
control signals to heat reclaim valves 56 and 156 to regulate the
positions thereof and provide the desired heating to heat loads 54
(e.g., via first heat reclaim heat exchanger 52 and second heat
reclaim heat exchanger 152). Controller 70 may provide control
signals to heat reclaim valves 57 and 157 to regulate the positions
thereof and provide the desired flow rate of the reclaim heat
exchange fluid through first heat reclaim heat exchanger 52 and
second heat reclaim heat exchanger 152 respectively. Controller 70
may provide control signals to condenser inlet valves 40-42 to
regulate the positions thereof and control condensation of the
refrigerant in condenser 32. Controller 70 may provide a control
signal to pressure regulation device 60 to substantially balance
the refrigerant pressure in downstream portion 58 of heat reclaim
branch 50 and downstream portion 44 of condenser branch 30.
[0027] Processing circuit 90 is shown to include a processor 92 and
memory 94. Processor 92 may be implemented as a general purpose
processor, an application specific integrated circuit (ASIC), one
or more field programmable gate arrays (FPGAs), a CPU, a GPU, a
group of processing components, or other suitable electronic
processing components.
[0028] Memory 94 may include one or more devices (e.g., RAM, ROM,
Flash.RTM. memory, hard disk storage, etc.) for storing data and/or
computer code for completing and/or facilitating the various
processes, layers, and modules described in the present disclosure.
Memory 94 may comprise volatile memory or non-volatile memory.
Memory 94 may include database components, object code components,
script components, or any other type of information structure for
supporting the various activities and information structures
described in the present disclosure. In some implementations,
memory 94 is communicably connected to processor 92 via processing
circuit 90 and includes computer code (e.g., data modules stored in
memory 94) for executing one or more control processes described
herein.
[0029] Still referring to FIG. 2, memory 94 is shown to include a
condensing mode control module 96, a heat reclaim mode control
module 98, a combined operating mode control module 100, a pressure
balance module 102, and an ambient temperature module 104.
[0030] Condensing mode control module 96 may be used to operate
refrigeration system 10 in a total condensing mode of operation. In
the total condensing mode of operation, controller 70 may direct
substantially all of the compressed refrigerant to one or more of
sections 34, 36, 38 of condenser 32 in condensing branch 30 (e.g.,
by closing heat reclaim valves 56 and 156, and opening one or more
of condenser inlet valves 40-42). The total condensing mode of
operation may be used when heating loads 54 are not available or
not in use, in order to condense all or substantially all of the
compressed refrigerant in use by the system 10.
[0031] Heat reclaim mode control module 98 may be used to operate
refrigeration system 10 in a total heat reclaim mode of operation.
In the total heat reclaim mode of operation, controller 70 may
direct all of the compressed refrigerant to heat reclaim heat
exchangers 52 and 152 in heat reclaim branch 50 (e.g., by opening
heat reclaim valves 56 and/or 156 and closing condenser inlet
valves 40-42). Heat reclaim mode control module 98 may open and
close heat reclaim valves 56 and 156 individually, simultaneously,
staggered in a predetermined sequence based on the demands of heat
loads 54, or in any other order or sequence. In some
implementations, the total heat reclaim mode of operation may be
used when heating loads 54 and ambient temperature conditions (e.g.
winter months or geographically colder climates) are sufficient to
condense all or substantially all of the compressed
refrigerant.
[0032] Combined operating mode control module 100 may be used to
operate refrigeration system 10 in a combined (e.g., mixed, hybrid,
partial condensing/heat reclaim, etc.) mode of operation. In the
combined mode of operation, controller 70 may direct a first
portion of the compressed refrigerant to one or more of heat
reclaim heat exchangers 52 and 152 in heat reclaim branch 50 (e.g.,
by modulating a position of heat reclaim valve 56 and/or 156).
Combined operating mode control module 100 may direct the remaining
portion of the compressed refrigerant to one or more of sections
34, 36, 38 of condenser 32 in condensing branch 30 (e.g., by
modulating a position of condenser inlet valves 40-42). Combined
operating mode control module 100 may use condenser 32 to condense
the remaining compressed refrigerant in use by refrigeration system
10 which is not condensed in heat reclaim heat exchangers 52 and
152. The combined mode of operation may be used when the heating
loads 54 and ambient temperature conditions are sufficient to
condense some, but not all, of the compressed refrigerant in use by
refrigeration system 10.
[0033] During the combined mode of operation, a pressure drop of
the compressed refrigerant through heat reclaim heat exchanger 52
and/or 152 in heat reclaim branch 50 may not be the same (or
substantially similar to) a pressure drop of the compressed
refrigerant through condenser 32 in condensing branch 30. In some
embodiments, the refrigerant pressure drop through condensing
branch 30 is greater than the refrigerant pressure drop through
heat reclaim branch 50. The greater pressure drop through
condensing branch 30 may result in the refrigerant pressure in
fluid conduit 58 being higher than the refrigerant pressure in
fluid conduit 44.
[0034] Since fluid conduits 58 and 44 are merged upstream of the
refrigeration loads (e.g. upstream of temperature-controlled
storage devices 20 and expansion devices 22, etc.), the higher
pressure in fluid conduit 58 may impede (or in some instances
prevent) the flow of refrigerant through condensing branch 30. For
example, a higher refrigerant pressure in fluid conduit 58 may act
as a "back pressure" which holds check valves 47-49 in a closed
position. In some embodiments, when the flow of refrigerant through
condenser 32 is impeded or prevented in this manner, the
refrigerant may condense and accumulate within condenser 32. In
other words, the refrigerant becomes "trapped." Accumulation of the
refrigerant within condenser 32 may deprive refrigeration system 10
of sufficient refrigerant for proper performance and operation of
temperature-controlled storage devices 20 (or other refrigeration
loads).
[0035] According to other embodiments, the refrigerant pressure
drop through heat reclaim branch 50 may be greater than the
refrigerant pressure drop through condensing branch 30. The greater
pressure drop through heat reclaim branch 50 may result in the
refrigerant pressure in fluid conduit 44 being higher than the
refrigerant pressure in fluid conduit 58. Both embodiments are
intended to be within the scope of this disclosure.
[0036] Still referring to FIG. 2, controller 70 is shown to include
a pressure balance module 102. Pressure balance module 102 may be
configured to balance the pressure of the refrigerant in fluid
conduit 44 (e.g., downstream of condensing branch 30) with the
pressure of the refrigerant in fluid conduit 58 (e.g., downstream
of heat reclaim branch 50). Advantageously, pressure balance module
102 may be used to ensure that the pressure drops through
condensing branch 30 and heat reclaim branch 50 (e.g., reductions
in the refrigerant pressure caused by refrigerant flow through
condensing branch 30 and heat reclaim branch 50) are substantially
equal during the combined mode of operation.
[0037] Pressure balance module 102 may provide control signal to
pressure regulation device 60. For embodiments in which the
pressure drop through heat reclaim branch 50 is less than the
pressure drop through condensing branch 30, pressure regulation
device may be provided upstream of fluid conduit 58. For
embodiments in which the pressure drop through condensing branch 30
is less than the pressure drop through heat reclaim branch 50,
pressure regulation device may be provided upstream of fluid
conduit 44. During the combined mode of operation, pressure balance
module 102 may modulate the position of pressure regulation device
60 (e.g., by opening and closing a valve of pressure regulation
device 60) to ensure that the refrigerant pressure in fluid conduit
44 is equal or substantially equal to the refrigerant pressure in
fluid conduit 58. Advantageously, balancing the pressures in fluid
conduits 44 and 58 may prevent a back pressure against check valves
47-49, thereby facilitating the flow of refrigerant through
condenser 32.
[0038] Still referring to FIG. 2, memory 94 is shown to include an
ambient temperature module 104. Ambient temperature module 104 may
control the positions of valves 40-42 in response to outdoor
ambient temperature conditions (e.g., at a location in which
refrigeration system 10 is installed). Ambient temperature module
104 may receive input from an ambient temperature sensor (not
shown) and modulate the positions of valves 40-42 based on the
ambient temperature. Ambient temperature module may control the
positions of valves 40-42 to split condenser 32 (e.g., by directing
refrigerant flow through one or more sections of condense 32) in
response to the outdoor ambient temperature.
[0039] For example, ambient temperature module 104 may be
configured to close valve 40 when the outdoor ambient temperature
is less than a first threshold temperature value. In some
embodiments, the first threshold temperature value is approximately
50.degree. F.-55.degree. F. Ambient temperature module 104 may be
configured to close valve 41 when the outdoor ambient temperature
is less than a second threshold temperature value. In some
embodiments, the second threshold temperature value is
approximately 30.degree. F.-35.degree. F. Closing valves 40 and 41
may cut off refrigerant flow through condenser portions 38 and 36
respectively.
[0040] Referring now to FIG. 3, a flowchart of a process 200 for
controlling refrigeration system 10 is shown, according to an
exemplary embodiment. Process 200 may be performed by controller 70
using one or more of the memory modules described above (e.g.,
memory modules 96-102). Process 200 may be used to switch between a
total condensing mode, a total heat reclaim mode, and a combined
operating mode based the values of several measured variables
(e.g., measured by sensors 72-78) and/or inputs received from
heating loads 54.
[0041] Process 200 is shown to include operating the refrigeration
system in a total condensing mode (step 202). Step 202 may include
closing valves 56 and 156 (or preventing valves 56 and 156 from
opening) to ensure that the refrigerant flows only through
condensing branch 30. Step 202 may further include opening one or
more of valves 40-42 to allow the refrigerant to flow through
condenser 32. The total condensing mode may be the default
operating mode in the absence of a call for heating from heating
loads 54.
[0042] Still referring to FIG. 3, process 200 is shown to further
include receiving a call for heating (step 204). The call for
heating may be received from heating loads 54. Heating loads 54 may
reflect a need for additional heat (e.g. from suitable temperature
monitoring instrumentation associated with the heating loads in the
facility, such as ambient space heating, hot water heating, etc.).
Heating loads 54 may include a heating device (e.g., an air
handling unit, a boiler, etc.) configured to provide heating for
the facility in which refrigeration system 10 operates. In some
embodiments, heating loads 54 may open a piping circuit for fluid
flow within the heating device and send a call for heating to
controller 70 signaling a need for heat.
[0043] Process 200 is shown to further include operating the
refrigeration in a first stage heat reclaim mode (step 206). Step
206 may be performed in response to the call for heating received
from heating loads 54 (e.g., in step 204). In some embodiments,
operating the refrigeration system in a first state heat reclaim
mode includes initiating operation of reheat heat exchange fluid
pump 55 for circulating the separate fluid from heat loads 54.
Controller 70 may include an interlock in which pump 55 will not
run if return pressure of the fluid to the suction of the pump
(e.g., immediately upstream of reheat heat exchange fluid pump 55)
is less than a predetermined pressure (e.g. about 2 psig or any
other suitable pressure) for a predetermined period of time (e.g.
about 10 minutes or any other suitable time). Step 206 may include
opening valve 57 to allow the separate fluid to flow through heat
exchanger 52.
[0044] Controller 70 operates refrigeration system 10 in a first
stage heat reclaim mode by sending a control signal to open heat
reclaim valve 56. Opening heat reclaim valve 56 may route the
refrigerant through heat reclaim heat exchanger 52. In some
embodiments, the control signal sent to heat reclaim valve 56 may
be interlocked with a signal from pump 55 indicating that reheat
exchange fluid pump 55 is operating. In some embodiments, operating
refrigeration system 10 in the first stage heat reclaim mode
includes closing valve 40, thereby preventing the refrigerant from
flowing through 50% condenser portion 38.
[0045] Still referring to FIG. 3, process 200 is shown to include
determining whether a heat reclaim is satisfied (step 208). Step
208 may include receiving an input from heating loads 54. In some
embodiments, controller 70 may determine that the heat reclaim is
satisfied when heating loads 54 no longer indicate a need for
heating. The heat reclaim may be satisfied when sufficient heat has
been delivered to heating loads 54 to satisfy the heating demands.
If the result of the determination in step 208 reveals that the
heat reclaim is satisfied, process 200 is shown to include
operating the system in the total condensing mode (e.g., step
202).
[0046] Process 200 is shown to include monitoring a temperature
T.sub.x of the reheat heat exchange fluid (step 210). In some
embodiments, step 210 may be performed in response to a
determination (e.g., in step 208) that the heat reclaim is not
satisfied. The reheat heat exchange fluid is the fluid pumped by
reheat heat exchange fluid pump 55 through heating loads 54. The
temperature T.sub.x of the reheat heat exchange fluid may be
measured by sensor 72. Sensor 72 may be upstream or downstream of
heating loads 54. Controller 70 may monitor the temperature T.sub.x
of the reheat heat exchange fluid by receiving an input signal from
sensor 72.
[0047] Still referring to FIG. 3, process 200 is shown to include
comparing the temperature T.sub.x of the reheat heat exchange fluid
with a first threshold temperature value T.sub.1 (step 212). Step
212 may be performed to determine whether additional heating is
required to meet the heating demand from heating loads 54. If the
result of the determination in step 212 reveals that the
temperature of the reheat heat exchange fluid is not less than the
first threshold temperature value (e.g., T.sub.x.gtoreq.T.sub.1),
controller 70 may continue to operate refrigeration system 10 in
the first state heat reclaim mode (e.g., by returning to step 206).
The first threshold temperature value T.sub.1 may be a
predetermined temperature value of approximately 95.degree. F. or
any other temperature value, depending on the particular
application.
[0048] Process 200 is shown to further include operating the
refrigeration system of a second stage heat reclaim mode (step
214). In some embodiments, step 214 may be performed in response to
a determination (e.g., in step 212) that the temperature of the
reheat heat exchange fluid is less than the first threshold
temperature value (e.g., T.sub.x<T.sub.1). In some embodiments,
step 214 may be performed in response to a determination that the
temperature of the reheat exchange fluid has been less than the
first threshold temperature value for a predetermined time period
(e.g., of approximately 10 minutes). In other embodiments, other
time values may be used for the predetermined time period,
depending on the particular implementation of refrigeration system
10.
[0049] The second stage heat reclaim mode may be initiated by
sending a control signal from controller 70 to open heat reclaim
valve 156, thereby routing the refrigerant through heat reclaim
heat exchanger 152. Valve 157 may also be opened (e.g., via a
control signal from controller 70) to allow the separate heat
reclaim fluid to flow through heat reclaim heat exchanger 152.
[0050] In some embodiments, controller 70 includes interlocks
associated with operation of the second stage heat reclaim mode.
The interlocks associated with the second stage heat reclaim mode
may cause controller 70 to close valves 41 and 42 associated with
the 25% capacity sections 34 and 36 of condenser 32 when valve 156
is opened. Closing valves 41 and 42 may prevent flow of refrigerant
through condenser 32. In some embodiments, the second stage heat
reclaim mode is a total heat reclaim mode in which the entirety of
the refrigerant is routed through heat reclaim branch 50.
[0051] Still referring to FIG. 3, process 200 is shown to include
comparing the temperature of the reheat heat exchange fluid T.sub.x
with a second threshold temperature value T.sub.2 (step 216). Step
216 may be performed to determine whether heat reclaim branch 50 is
capable of removing sufficient heat from the compressed
refrigerant. If the result of the determination in step 216 reveals
that the temperature of the reheat heat exchange fluid is not
greater than the second threshold temperature value (e.g.,
T.sub.x.ltoreq.T.sub.2), controller 70 may continue to operate
refrigeration system 10 in the second state heat reclaim mode
(e.g., by returning to step 212). The second threshold temperature
value T.sub.2 may be a predetermined temperature value of
approximately 108.degree. F. or any other temperature value,
depending on the particular implementation of refrigeration system
10.
[0052] If the result of the determination in step 216 reveals that
the temperature of the reheat heat exchange fluid is greater than
the second threshold temperature (e.g., T.sub.x>T.sub.2),
controller 70 may revert to operating refrigeration system 10 in
the first stage heat reclaim mode (step 206). Returning to the
first stage heat reclaim mode may include closing heat reclaim
valve 156 to stop refrigerant flow through second stage heat
reclaim heat exchanger 152. Valve 157 may also be closed to prevent
the flow of the separate reheat heat exchange fluid through heat
exchanger 152. Returning to the first stage heat reclaim mode may
further include opening valves 41-42 to allow the refrigerant to
flow through condenser sections 34 and 36. Controller 70 may start
and stop operation of the second stage heat reclaim mode as needed
to supplement the first stage heat reclaim mode in meeting the
heating demand from the heat loads 54.
[0053] When the system is operated in the second stage heat reclaim
mode, refrigeration system 10 may attempt to remove all heat from
the refrigerant using heat reclaim branch 50. System 10 may be
operated in the second stage heat reclaim mode, for example, in
response to a determination (e.g., in step 212) that the
temperature of the reheat heat exchange fluid is less than the
first threshold temperature value (e.g., T.sub.x<T.sub.I) or
when ambient temperature conditions cause ambient temperature
module 104 to close all of valves 40-42 (e.g., when the ambient
temperature is less than 30.degree. F.-35.degree. F.).
[0054] If the heating devices of heat loads 54 cannot remove
sufficient heat from the refrigeration loop to maintain the
refrigerant pressure at the discharge of compressors 26 (i.e. in
line 28) at a predetermined level (e.g. a pressure corresponding to
approximately 95.degree. F. saturated discharge temperature),
bypass valve 46 may be opened to allow the refrigerant to bypass
closed valve 42 and flow through condenser section 34. Bypass valve
46 may receive a signal directly from sensor 80 indicating a
temperature and/or pressure of the refrigerant in line 28.
Advantageously, bypassing the refrigerant through bypass valve 46
may allow condensing branch 30 to remove any excess heat that heat
reclaim branch 50 cannot dissipate through the heat loads 54.
[0055] Bypass valve 46 may be configured to maintain a closed
position when the pressure in line 28 is below a predetermined
value. The predetermined value may be representative of a safe
operating pressure necessary to provide a maximum amount of heat to
heat reclaim branch 50. When the pressure of the compressed hot gas
refrigerant in line 28 exceeds the predetermined value, bypass
valve 46 may open to allow the refrigerant to bypass valve 42 and
enter condenser section 34. Advantageously, using bypass valve 46
in this manner may avoid excessive cycling of valve 42 as would
otherwise be necessary to remove any excess heat which cannot be
removed via heat reclaim branch 50. Additionally, bypass valve 46
may reduce frequency with which controller 70 is required to switch
between operating modes by providing an additional mechanism (e.g.,
independent of controller 70) to remove heat from the
refrigerant.
[0056] According to any exemplary embodiment, pressure regulation
device 60 operates during the combined mode of operation (e.g.,
when refrigerant is flowing through both condensing branch 30 and
heat reclaim condensing branch 50) to maintain the pressure in the
reheat discharge line (i.e., fluid conduit 58) at a level that is
substantially equal to the pressure in the condensing discharge
line (i.e., fluid conduit 44). Advantageously, pressure regulation
device may prevent check valves 47-49 from closing due to back
pressure and flooding one or more of the condenser portions 34, 36
and/or 38.
[0057] According to any exemplary embodiment, the various
temperature-controlled storage devices of the present disclosure
may have different storage temperature requirements (e.g. "low
temperature," such as approximately -20.degree. F., or "medium
temperature," such as approximately 25.degree. F.). Storage devices
may have a variety of applications. One example of a storage device
is a refrigerated display case in a supermarket for use in
displaying refrigerated or frozen food products. Such
temperature-controlled storage devices may have one or more glass
doors that provide access to a temperature controlled space, or may
have an open front with an air curtain. All such variations are
intended to be within the scope of this disclosure.
[0058] The various temperatures of the storage devices and the
refrigerants illustrated or described in the various embodiments,
are shown by way of example only. A wide variety of other
temperatures and temperature ranges may be used to suit any
particular application and are intended to be within the scope of
this disclosure. Also, the various flow rates, capacity and
balancing of refrigerants are described by way of example and may
be modified to suit a wide variety of applications depending on the
number of storage devices, the temperature requirements of the
storage devices, the heating demands from the heat loads, the
pressure drops through the one or more sections of the condenser
and the heat reclaim heat exchanger(s), etc.
[0059] It should also be noted that any references to "upstream,"
and "downstream" in this description are merely used to identify
the various elements as they are oriented in the FIGURES, being
relative to a specific direction. These terms are not meant to
limit the element which they describe, as the various elements may
be oriented differently in various applications.
[0060] As utilized herein, the terms "approximately," "about,"
"substantially," and similar terms are intended to have a broad
meaning in harmony with the common and accepted usage by those of
ordinary skill in the art to which the subject matter of this
disclosure pertains. It should be understood by those of skill in
the art who review this disclosure that these terms are intended to
allow a description of certain features described and claimed
without restricting the scope of these features to the precise
numerical ranges provided. Accordingly, these terms should be
interpreted as indicating that insubstantial or inconsequential
modifications or alterations of the subject matter described and
claimed are considered to be within the scope of the invention as
recited in the appended claims.
[0061] It should be noted that the term "exemplary" as used herein
to describe various embodiments is intended to indicate that such
embodiments are possible examples, representations, and/or
illustrations of possible embodiments (and such term is not
intended to connote that such embodiments are necessarily
extraordinary or superlative examples).
[0062] The terms "coupled," "connected," and the like as used
herein mean the joining of two members directly or indirectly to
one another. Such joining may be stationary (e.g., permanent) or
moveable (e.g., removable or releasable). Such joining may be
achieved with the two members or the two members and any additional
intermediate members being integrally formed as a single unitary
body with one another or with the two members or the two members
and any additional intermediate members being attached to one
another.
[0063] It should be noted that the orientation of various elements
may differ according to other exemplary embodiments, and that such
variations are intended to be encompassed by the present
disclosure.
[0064] It is also important to note that the construction and
arrangement of the elements of the system with pressure-balanced
heat reclaim as shown in the exemplary embodiments are illustrative
only. Although only a few embodiments of the present disclosure
have been described in detail, those skilled in the art who review
this disclosure will readily appreciate that many modifications are
possible (e.g., variations in sizes, dimensions, structures, shapes
and proportions of the various elements, values of parameters,
mounting arrangements, use of materials, colors, orientations,
etc.) without materially departing from the novel teachings and
advantages of the subject matter recited. For example, elements
shown as integrally formed may be constructed of multiple parts or
elements. It should be noted that the elements and/or assemblies of
the enclosure may be constructed from any of a wide variety of
materials that provide sufficient strength or durability, in any of
a wide variety of colors, textures, and combinations. Additionally,
in the subject description, the word "exemplary" is used to mean
serving as an example, instance or illustration. Any embodiment or
design described herein as "exemplary" is not necessarily to be
construed as preferred or advantageous over other embodiments or
designs. Rather, use of the word exemplary is intended to present
concepts in a concrete manner. Accordingly, all such modifications
are intended to be included within the scope of the present
inventions. Other substitutions, modifications, changes, and
omissions may be made in the design, operating conditions, and
arrangement of the preferred and other exemplary embodiments
without departing from the spirit of the appended claims.
[0065] The order or sequence of any process or method steps may be
varied or re-sequenced according to alternative embodiments. Any
means-plus-function clause is intended to cover the structures
described herein as performing the recited function and not only
structural equivalents but also equivalent structures. Other
substitutions, modifications, changes and omissions may be made in
the design, operating configuration, and arrangement of the
preferred and other exemplary embodiments without departing from
the spirit of the appended claims.
* * * * *