U.S. patent application number 11/837356 was filed with the patent office on 2008-02-14 for thermal energy storage and cooling system with isolated external melt cooling.
This patent application is currently assigned to ICE ENERGY, INC.. Invention is credited to Ramachandran Narayanamurthy, Mark W. Stewart, Robert R. Willis.
Application Number | 20080034760 11/837356 |
Document ID | / |
Family ID | 38669885 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080034760 |
Kind Code |
A1 |
Narayanamurthy; Ramachandran ;
et al. |
February 14, 2008 |
THERMAL ENERGY STORAGE AND COOLING SYSTEM WITH ISOLATED EXTERNAL
MELT COOLING
Abstract
Disclosed are a method and device for a refrigerant-based
thermal energy storage and cooling system with isolated external
melt cooling. The disclosed embodiments provide a refrigerant-based
ice storage system with increased reliability, lower cost
components, and reduced power consumption compared to a single
phase system such as a glycol system.
Inventors: |
Narayanamurthy; Ramachandran;
(Loveland, CO) ; Stewart; Mark W.; (Whitehouse,
NJ) ; Willis; Robert R.; (Fort Collins, CO) |
Correspondence
Address: |
COCHRAN FREUND & YOUNG LLC
2026 CARIBOU DR, SUITE 201
FORT COLLINS
CO
80525
US
|
Assignee: |
ICE ENERGY, INC.
Windsor
CO
|
Family ID: |
38669885 |
Appl. No.: |
11/837356 |
Filed: |
August 10, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60822034 |
Aug 10, 2006 |
|
|
|
Current U.S.
Class: |
62/59 ;
62/434 |
Current CPC
Class: |
Y02E 60/147 20130101;
Y02E 60/14 20130101; F24F 5/0017 20130101 |
Class at
Publication: |
62/59 ;
62/434 |
International
Class: |
F25D 3/02 20060101
F25D003/02; F25D 17/02 20060101 F25D017/02 |
Claims
1. A refrigerant-based thermal energy storage and cooling system
comprising: a refrigerant loop containing a refrigerant comprising:
a condensing unit, said condensing unit comprising a compressor and
a condenser; an expansion device connected downstream of said
condensing unit; and, a primary heat exchanger that acts as an
evaporator and is located within a tank filled with a fluid capable
of a phase change between liquid and solid, said primary heat
exchanger that facilitates heat transfer from said refrigerant from
said condenser to cool said fluid and to freeze at least a portion
of said fluid within said tank; a cooling loop containing said
fluid from said tank comprising: a load heat exchanger connected to
said tank that transfers cooling capacity of said fluid to a heat
load; and, a pump that distributes said fluid from said tank to
said load heat exchanger and returns said fluid to said tank.
2. The system of claim 1 further comprising: a refrigerant
management vessel in fluid communication with, and located between
said condensing unit and said primary heat exchanger comprising: an
inlet connection that receives refrigerant from said condensing
unit and said primary heat exchanger; a first outlet connection
that supplies refrigerant to said primary heat exchanger; and, a
second outlet connection that supplies refrigerant to said
condensing unit.
3. The system of claim 1 wherein said expansion device is a thermal
expansion valve.
4. The system of claim 1 wherein said expansion device is a
mixed-phase regulator.
5. The system of claim 1 wherein said fluid is a eutectic
material.
6. The system of claim 1 wherein said fluid is water.
7. The system of claim 1 wherein said first refrigerant is a
different material from said second refrigerant.
8. The system of claim 1 wherein said load heat exchanger is at
least one mini-split evaporator.
9. A refrigerant-based thermal energy storage and cooling system
comprising: a first refrigerant loop containing a first refrigerant
comprising: a condensing unit, said condensing unit comprising a
compressor and a first condenser; an expansion device connected
downstream of said condensing unit; and, a first evaporator on a
primary side of an isolating heat exchanger located downstream of
said expansion device; a second refrigerant loop containing a
second refrigerant comprising: a second condenser on a secondary
side of said isolating heat exchanger; a tank filled with a fluid
capable of a phase change between liquid and solid and containing a
primary heat exchanger therein, said primary heat exchanger in
fluid communication with said second condenser and that utilizes
said second refrigerant from said second condenser to cool said
fluid and to freeze at least a portion of said fluid within said
tank; a load heat exchanger connected in fluid communication with
said fluid in said tank that transfers cooling capacity of said
fluid to a heat load; and, a pump for distributing said fluid from
said tank to said to said load heat exchanger.
10. The system of claim of claim 9 further comprising: a
refrigerant management vessel connected to receive said second
refrigerant from said isolating heat exchanger and supply said
second refrigerant to said primary heat exchanger, and to receive
said second refrigerant from said primary heat exchanger and supply
said second refrigerant to said isolating heat exchanger.
11. The system of claim 9 wherein said expansion device is a
thermal expansion valve.
12. The system of claim 9 wherein said expansion device is a
mixed-phase regulator.
13. The system of claim 9 wherein said fluid is a eutectic
material.
14. The system of claim 9 wherein said fluid is water.
15. The system of claim 9 wherein said first refrigerant is a
different material from said second refrigerant.
16. The system of claim 9 wherein said load heat exchanger is at
least one mini-split evaporator.
17. The system of claim 9 further comprising: a by-pass refrigerant
loop that allows said first refrigerant to by-pass said primary
heat exchanger and provide cooling directly to said fluid
downstream of said tank and transfer cooling to said heat load.
18. A refrigerant-based thermal energy storage and cooling system
comprising: a first refrigerant loop containing a first refrigerant
comprising: a condensing unit, said condensing unit comprising a
compressor and a condenser; an expansion device connected
downstream of said condensing unit; and, a primary heat exchanger
that acts as an evaporator and is located within a tank filled with
a fluid capable of a phase change between liquid and solid, said
primary heat exchanger that facilitates heat transfer from said
first refrigerant from said condenser to cool said fluid and to
freeze at least a portion of said fluid within said tank; a cooling
loop containing said fluid from said tank comprising: an
intermediate heat exchanger connected to said tank that transfers
cooling capacity of said fluid to a primary side of said
intermediate heat exchanger; a pump that distributes said fluid
from said tank to said intermediate (load) heat exchanger and
returns said fluid to said tank; a second refrigerant loop
containing a second refrigerant comprising: a load heat exchanger
connected in fluid communication with a secondary side of said
intermediate heat exchanger that transfers cooling capacity of said
second refrigerant to a heat load; and, a refrigerant pump for
distributing said second refrigerant from said intermediate heat
exchanger to said load heat exchanger and back to said intermediate
heat exchanger.
19. The system of claim 18 wherein said expansion device is a
thermal expansion valve.
20. The system of claim 18 wherein said expansion device is a
mixed-phase regulator.
21. The system of claim 18 wherein said fluid is a eutectic
material.
22. The system of claim 18 wherein said fluid is water.
23. The system of claim 18 wherein said first refrigerant is a
different material from said second refrigerant.
24. The system of claim 18 wherein said load heat exchanger is at
least one mini-split evaporator.
25. The system of claim 18 wherein said second refrigerant remains
liquid.
26. The system of claim 18 further comprising: a refrigerant
management vessel connected to receive said second refrigerant from
said isolating heat exchanger and supply said second refrigerant to
said primary heat exchanger, and to receive said second refrigerant
from said primary heat exchanger and supply said second refrigerant
to said isolating heat exchanger:
27. The system of claim 18 further comprising: a by-pass
refrigerant loop that allows said first refrigerant to by-pass said
primary heat exchanger and provide cooling directly to said fluid
downstream of said tank and transfer cooling to said intermediate
heat exchanger.
28. A method of providing cooling with a refrigerant-based thermal
energy storage and cooling system comprising the steps of:
providing cooling to a primary heat exchanger by evaporating a
high-pressure refrigerant in said primary heat exchanger that is
constrained within a tank containing a fluid capable of a phase
change between liquid and solid; freezing a portion of said fluid
and form ice within said tank; delivering a liquid portion of said
fluid to a load heat exchanger; transferring cooling from said
liquid portion of said fluid to said load heat exchanger to provide
load cooling; returning said liquid portion of said fluid to said
tank; and, cooling said liquid portion of said fluid with said ice
within said tank.
29. The method of claim 28 further comprising the step of: managing
volumes and phase of said first refrigerant with a refrigerant
management vessel, said refrigerant management vessel in fluid
communication with said primary heat exchanger and said
condenser.
30. A method of providing cooling with a refrigerant-based thermal
energy storage and cooling system comprising the steps of:
providing cooling to a first evaporator on a primary side of an
isolating heat exchanger by evaporating a high-pressure refrigerant
in said first evaporator; transferring cooling from said primary
side of said isolating heat exchanger to a second refrigerant loop
containing a second refrigerant through a secondary side of said
isolating heat exchanger; providing cooling with said second
refrigerant loop to a primary heat exchanger that is constrained
within a tank containing a fluid capable of a phase change between
liquid and solid; freezing a portion of said fluid and form ice
within said tank; delivering a liquid portion of said fluid to a
load heat exchanger; transferring cooling from said liquid portion
of said fluid to said load heat exchanger to provide load cooling;
returning said liquid portion of said fluid to said tank; and,
cooling said liquid portion of said fluid with said ice within said
tank.
31. The method of claim 30 further comprising the step of: managing
volumes and phase of said second refrigerant with a refrigerant
management vessel, said refrigerant management vessel in fluid
communication with said isolating heat exchanger and said primary
heat exchanger.
32. The method of claim 30 further comprising the step of:
by-passing said primary heat exchanger with said primary
refrigerant; delivering said primary refrigerant to said to said
fluid downstream of said tank; and, transferring cooling to said
intermediate heat exchanger.
33. A method of providing cooling with a refrigerant-based thermal
energy storage and cooling system comprising the steps of:
providing cooling to a primary heat exchanger by evaporating a
high-pressure refrigerant in said primary heat exchanger that is
constrained within a tank containing a fluid capable of a phase
change between liquid and solid; freezing a portion of said fluid
and form ice within said tank; delivering a liquid portion of said
fluid to a primary side of an intermediate heat exchanger;
transferring cooling from said primary side of said intermediate
heat exchanger to a second refrigerant loop containing a second
refrigerant through a secondary side of said intermediate heat
exchanger; returning said liquid portion of said fluid to said
tank; cooling said liquid portion of said fluid with said ice
within said tank; delivering said second refrigerant to a load heat
exchanger; transferring cooling from said second refrigerant to a
load heat exchanger to provide load cooling; returning said second
refrigerant to said secondary side of said intermediate heat
exchanger; and, cooling said second refrigerant with said primary
side of said intermediate heat exchanger.
34. The method of claim 33 further comprising the step of: managing
volumes and phase of said first refrigerant with a refrigerant
management vessel, said refrigerant management vessel in fluid
communication with said primary heat exchanger and said
condenser.
35. The method of claim 33 further comprising the step of:
isolating said primary heat exchanger from said condensing unit
with an isolating heat exchanger that transfers heat to and from
said primary heat exchanger and said condensing unit.
36. The method of claim 33 further comprising the step of:
maintaining said second refrigerant in liquid phase throughout said
second refrigerant loop.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
U.S. provisional application No. 60/822,034, entitled "Thermal
Energy Storage and Cooling System with Isolated External Melt
Cooling", filed Aug. 10, 2006, the entire disclosure of which is
hereby specifically incorporated by reference for all that it
discloses and teaches.
BACKGROUND OF THE INVENTION
[0002] With the increasing demands on peak demand power
consumption, ice storage has been utilized to shift air
conditioning power loads to off-peak times and rates. A need exists
not only for load shifting from peak to off-peak periods, but also
for increases in air conditioning unit capacity and efficiency.
Current air conditioning units having energy storage systems have
had limited success due to several deficiencies including reliance
on water chillers that are practical only in large commercial
buildings and have difficulty achieving high-efficiency. In order
to commercialize advantages of thermal energy storage in large and
small commercial buildings, thermal energy storage systems must
have minimal manufacturing costs, maintain maximum efficiency under
varying operating conditions, emanate simplicity in the refrigerant
management design, and maintain flexibility in multiple
refrigeration or air conditioning applications.
[0003] Systems for providing thermal stored energy have been
previously contemplated in U.S. Pat. No. 4,735,064, U.S. Pat. No.
5,225,526, both issued to Harry Fischer, U.S. Pat. No. 5,647,225
issued to Fischer et al., U.S. Pat. No. 7,162,878 issued Jan. 16,
2007 by Narayanamurthy et al., U.S. patent application Ser. No.
11/112,861 filled Apr. 22, 2005 by Narayanamurthy et al., U.S.
patent application Ser. No. 11/138,762 filed May 25, 2005 by
Narayanamurthy et al., U.S. patent application Ser. No. 11/208,074
filed Aug. 18, 2005 by Narayanamurthy et al. and U.S. patent
application Ser. No. 11/284,533 filed Nov. 21, 2005 by
Narayanamurthy et al. All of these patents utilize ice storage to
shift air conditioning loads from peak to off-peak electric rates
to provide economic justification, and are hereby specifically
incorporated by reference herein for all they teach and
disclose.
SUMMARY OF THE INVENTION
[0004] An embodiment of the present invention may therefore
comprise a refrigerant-based thermal energy storage and cooling
system comprising: a refrigerant loop containing a refrigerant
comprising: a condensing unit, the condensing unit comprising a
compressor and a condenser; an expansion device connected
downstream of the condensing unit; and, a primary heat exchanger
that acts as an evaporator and is located within a tank filled with
a fluid capable of a phase change between liquid and solid, the
primary heat exchanger that facilitates heat transfer from the
refrigerant from the condenser to cool the fluid and to freeze at
least a portion of the fluid within the tank; a cooling loop
containing the fluid from the tank comprising: a load heat
exchanger connected to the tank that transfers cooling capacity of
the fluid to a heat load; and, a pump that distributes the fluid
from the tank to the load heat exchanger and returns the fluid to
the tank.
[0005] An embodiment of the present invention may also comprise a
refrigerant-based thermal energy storage and cooling system
comprising: a first refrigerant loop containing a first refrigerant
comprising: a condensing unit, the condensing unit comprising a
compressor and a first condenser; an expansion device connected
downstream of the condensing unit; and, a first evaporator on a
primary side of an isolating heat exchanger located downstream of
the expansion device; a second refrigerant loop containing a second
refrigerant comprising: a second condenser on a secondary side of
the isolating heat exchanger; a tank filled with a fluid capable of
a phase change between liquid and solid and containing a primary
heat exchanger therein, the primary heat exchanger in fluid
communication with the second condenser and that utilizes the
second refrigerant from the second condenser to cool the fluid and
to freeze at least a portion of the fluid within the tank; a load
heat exchanger connected in fluid communication with the fluid in
the tank that transfers cooling capacity of the fluid to a heat
load; and, a pump for distributing the fluid from the tank to the
to the load heat exchanger.
[0006] An embodiment of the present invention may also comprise a
method of providing cooling with a refrigerant-based thermal energy
storage and cooling system comprising the steps of: providing
cooling to a primary heat exchanger by evaporating a high-pressure
refrigerant in the primary heat exchanger that is constrained
within a tank containing a fluid capable of a phase change between
liquid and solid; freezing a portion of the fluid and form ice
within the tank; delivering a liquid portion of the fluid to a load
heat exchanger; transferring cooling from the liquid portion of the
fluid to the load heat exchanger to provide load cooling; returning
the liquid portion of the fluid to the tank; cooling the liquid
portion of the fluid with the ice within the tank.
[0007] An embodiment of the present invention may also comprise a
method of providing cooling with a refrigerant-based thermal energy
storage and cooling system comprising the steps of: providing
cooling to a primary heat exchanger by evaporating a high-pressure
refrigerant in the primary heat exchanger that is constrained
within a tank containing a fluid capable of a phase change between
liquid and solid; freezing a portion of the fluid and form ice
within the tank; delivering a liquid portion of the fluid to a
primary side of an intermediate heat exchanger; transferring
cooling from the primary side of the intermediate heat exchanger to
a second refrigerant loop containing a second refrigerant through a
secondary side of the intermediate heat exchanger; returning the
liquid portion of the fluid to the tank; cooling the liquid portion
of the fluid with the ice within the tank; delivering the second
refrigerant to a load heat exchanger; transferring cooling from the
second refrigerant to a load heat exchanger to provide load
cooling; returning the second refrigerant to the secondary side of
the intermediate heat exchanger; cooling the second refrigerant
with the primary side of the intermediate heat exchanger.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] In the drawings,
[0009] FIG. 1 illustrates an embodiment of a refrigerant-based
thermal energy storage and cooling system with isolated external
melt cooling.
[0010] FIG. 2 illustrates an embodiment of a refrigerant-based
thermal energy storage and cooling system with isolated external
melt cooling that utilizes a universal refrigerant management
vessel.
[0011] FIG. 3 illustrates a configuration of an embodiment of a
refrigerant-based thermal energy storage and cooling system with
secondary refrigerant isolation and isolated external melt
cooling.
[0012] FIG. 4 illustrates a configuration of an embodiment of a
refrigerant-based thermal energy storage and cooling system with
secondary refrigerant isolation and direct cooling (bypass)
capability.
[0013] FIG. 5 illustrates a configuration of an embodiment of a
refrigerant-based thermal energy storage and cooling system with
secondary refrigerant isolation and a secondary refrigerant
loop.
DETAILED DESCRIPTION OF THE INVENTION
[0014] While this invention is susceptible to embodiment in many
different forms, there is shown in the drawings and will be
described herein in detail specific embodiments thereof with the
understanding that the present disclosure is to be considered as an
exemplification of the principles of the invention and is not to be
limited to the specific embodiments described.
[0015] FIG. 1 illustrates an embodiment of a refrigerant-based
thermal energy storage and cooling system with isolated external
melt cooling. This embodiment may function with or without an
accumulator vessel or URMV (universal refrigerant management
vessel), and is depicted in FIG. 1 without the vessel. FIG. 2
depicts the system with a URMV. This embodiment incorporates an air
conditioner unit 102 utilizing a compressor 110 to compress cold,
low pressure refrigerant gas to hot, high-pressure gas. Next, a
condenser 111 removes much of the heat in the gas and discharges
the heat to the atmosphere. The refrigerant comes out of the
condenser as a warm, high-pressure liquid refrigerant delivered
through a high-pressure liquid supply line 112 to an expansion
device 130 and to a thermal energy storage unit 106 via feed tube
192. This expansion device 130 may be a conventional or
non-conventional thermal expansion valve, a mixed-phase regulator
and surge vessel (reservoir) or the like. Cooling is transferred to
the thermal energy storage unit 106 by the primary heat exchanger
160 as expanding refrigerant is fed from a lower header assembly
156 through the freezing/discharge coils 142, to the upper header
assembly 154. Low-pressure vapor phase and liquid refrigerant is
then returned to compressor 110 via low pressure return line 118
completing the refrigeration loop.
[0016] The thermal energy storage unit 106 comprises an insulated
tank 140 that houses the primary heat exchanger 160 surrounded by a
thermal reservoir such as a phase change material (typically
fluid/ice depending on the current system mode). The primary heat
exchanger 160 further comprises a lower header assembly 156
connected to an upper header assembly 154 with a series of freezing
and discharge coils 142 to make a fluid/vapor loop within the
insulated tank 140. The upper and lower header assemblies 154 and
156 communicate externally of the thermal energy storage unit 106
with inlet and outlet connections.
[0017] The embodiment illustrated in FIG. 1 utilizes at least one
conventional air conditioner unit 102 as the principal cooling
source. Multiple air conditioner units may be utilized without
departing from the spirit of the invention. The thermal energy
storage unit 106 operates using an independent refrigerant loop
that transfers the cooling between the air conditioner unit 102 and
the thermal energy storage unit 106. The disclosed embodiment
functions in two principal modes of operation, charging (ice-make)
and cooling (ice-melt) mode.
[0018] In charging mode, compressed high-pressure refrigerant
leaves the air conditioner unit 102 through high-pressure liquid
supply line 112 and is fed through an expansion device 130 to cool
the thermal energy storage unit 106 where it enters the primary
heat exchanger 160 through the lower header assembly 156 and is
then distributed through the freezing coils 142 which act as an
evaporator. Cooling is transmitted from the freezing coils 142 to
the surrounding liquid phase change material 152 that is confined
within the insulated tank 140 and freezes at least a portion of the
phase change material 153 (ice) surrounding the freezing coils 142
and storing thermal energy in the process. Warm liquid and vapor
phase refrigerant leaves the freezing coils 142 through the upper
header assembly 154 and exits the thermal energy storage unit 106
returning to the air conditioner unit 102 through the low pressure
return line 118 and is fed to the compressor 110 and re-condensed
into liquid.
[0019] In cooling mode, cool liquid phase change material leaves
the lower portion of the insulated tank 140 and is propelled by a
pump 120 to a load heat exchanger 122 where cooling is transferred
to a load with the aid of an air handler 150. This load heat
exchanger 122 may be a single or multiple evaporators such as might
be used to provide multi-zone cooling, mini-split evaporators or
the like. Warm liquid leaves load heat exchanger 122 where the
liquid is returned to header 154 of the thermal energy storage unit
106 and draws cooling from the solid phase change material 153
surrounding the coils.
[0020] Because the system isolates the primary refrigerant from a
secondary phase change material loop, the system additionally
allows the use of a variety of refrigerants to be used within the
device. For example, one type of highly efficient refrigerant that
may have properties that would discourage use within a dwelling
(such as propane) may be utilized within the primary refrigerant
loop, while a more suitable material (such as water, ammonia,
slurry ice, brine, ethylene glycol, propylene glycol, various
alcohols (Isobutyl, ethanol), sugar, other eutectic materials or
the like) can be used for the secondary loop that may enter the
dwelling. This allows greater versatility and efficiency of the
system while maintaining safety, environmental and application
issues to be addressed.
[0021] The embodiment illustrated in FIG. 2 shows the system of
FIG. 1 further utilizing an accumulator vessel or URMV. As
described in the previous embodiment, the thermal energy storage
unit 106 operates using an independent refrigerant loop that
transfers the cooling between the air conditioner unit 102 and the
thermal energy storage unit 106. In this example, acting as a
collector and phase separator of multi-phase refrigerant, the
accumulator or universal refrigerant management vessel (URMV) 146
is in fluid communication with both the thermal energy storage unit
106 and the air conditioner unit 102.
[0022] The disclosed embodiment also functions in two principal
modes of operation, charging (ice-make) and cooling (ice-melt)
mode. Cooling mode is identical to that of FIG. 1 and ice-make
includes the additional function of the URMV. In charging mode, the
URMV 146 accumulates liquid refrigerant leaving the expansion
device 130 and separates vapor phase refrigerant from the liquid
phase refrigerant. Condensed refrigerant leaves the lower portion
of the URMV 146 through a first outlet and is expanded in the coils
of the thermal energy storage unit 106 where cooling is transferred
to the phase change material within the insulated tank 140.
Expanded refrigerant leaves the thermal energy storage unit 106 and
returns to the upper portion of the URMV where remaining liquid
phase refrigerant is accumulated in the URMV and vapor phase
refrigerant is returned to the air conditioner unit through a
second outlet for compression, condensation and heat
extraction.
[0023] FIG. 3 illustrates an embodiment of a refrigerant-based
thermal energy storage and cooling system with secondary
refrigerant isolation and isolated external melt cooling. As with
the embodiment of FIG. 1, the disclosed system functions with or
without an accumulator vessel or URMV. FIG. 3 depicts the system
without the vessel and FIG. 4 depicts the system with a URMV. The
present embodiment utilizes a primary refrigeration loop 101 that
includes at least one air conditioner unit 102 with a compressor
110 and condenser 111 creating high-pressure liquid refrigerant
that is delivered through a high-pressure liquid supply line 112 to
an isolating heat exchanger 162 through an expansion device 130.
Low-pressure refrigerant is returned to compressor 110 via low
pressure return line 118. An additional benefit of incorporating a
URMV within the system is that it allows additional application
flexibility with the geometry of the refrigerant lines. This
additional refrigerant reservoir facilitates longer line lengths of
the refrigerant lines, and thus, greater distance tolerances for
locating components.
[0024] Cooling is transferred through the isolating heat exchanger
162 to a thermal energy storage unit 106 within a secondary
refrigeration loop 103. This thermal energy storage unit 106 is
comparable to that depicted in FIG. 1, and acts as an evaporator
during an ice-make cycle. A load heat exchanger 122 in conjunction
with an air handler 150 is connected within an external melt
cooling loop 105 to transmit cooling from thermal energy storage
unit 106 and provide isolated cooling in one mode.
[0025] Valves may be placed in various places within the secondary
refrigerant loop 103 and external melt cooling loop 105 to allow
multi-mode conditions with minimal complexity and plumbing. A pump
120 is placed in the external melt cooling loop 105 to pump cold
liquid phase change material from the insulated tank 140 to the
load heat exchanger 122 and back to the thermal energy storage unit
106 in cooling mode. This load heat exchanger 122 may be a single
or multiple evaporators such as might be used to provide multi-zone
cooling, mini-split evaporators or the like.
[0026] The present embodiment may function in two principal modes
of operation, ice-make and ice-melt. In ice-make or charge mode,
the primary refrigerant loop 102 is used to cool the primary side
of the isolating heat exchanger 162 that transfers heat to the
secondary refrigerant loop 103. The secondary refrigerant loop 103
can be either pump driven by adding a refrigerant pump within the
loop, typically between the isolating heat exchanger 162 and the
lower header assembly 156 (not shown), or gravity feed (as shown
and described). The gravity feed system of FIG. 3 is self
equalizing when in charging mode with respect to the effectiveness
of the freezing/discharge coils 142.
[0027] This self equalization that occurs during the ice build mode
can be beneficial. Large stresses can be applied to the ice storage
heat exchanger during uneven ice builds which can ultimately result
in mechanical failure or rupture of the heat exchanger. Pump feed
systems cannot self equalize because refrigerant is forced into
each coil regardless of the amount of ice already surrounding the
coil. Another advantage to a gravity feed system is the absence of
a pump which requires a power source and also adds additional
potential failure modes to the system.
[0028] In either gravity or pump fed systems, the secondary
refrigerant loop 103 carries cooled condensed refrigerant to the
thermal energy storage unit 106 where it enters the primary heat
exchanger 160 through the lower header assembly 156 and is then
distributed through the freezing coils 142 which act as an
evaporator. Cooling is transmitted from the freezing coils 142 to
the surrounding liquid phase change material 152 that is confined
within the insulated tank 140 and freezes at least a portion of the
phase change material 153 (ice) surrounding the freezing coils 142
and storing thermal energy in the process. Within the insulated
tank 140, a portion of the phase change material remains liquid and
typically will surround the solid material (although a slurry may
also be used). This cold liquid phase change material 152 is drawn
from the lower portion of the insulated tank 140 within the thermal
energy storage unit 106 with a pump 120 and circulated through the
load heat exchanger 122 and used to cool a heat load utilizing an
air handler 150. Warm liquid phase change material 152 leaves the
load heat exchanger 122 and is returned to the insulated tank 140
where it is cooled by melting the solid phase change material 153
(ice) surrounding the freezing coils 142.
[0029] In charging mode, the thermal energy storage unit 106 acts
as an evaporator and cooling is transmitted to fluid that is
confined within the thermal energy storage unit 106 thus storing
thermal energy. Warm liquid and vapor phase refrigerant leaves the
freezing coils 142 through the upper header assembly 154 and exits
the thermal energy storage unit 106 returning to the isolating heat
exchanger 162 and re-condensed into liquid.
[0030] In ice-melt or cooling mode, the primary refrigerant loop
102 can continue to cool, can be shut down, or can be disengaged.
Cool liquid refrigerant is drawn from the thermal energy storage
unit 106 and is pumped by a pump 120 to the load heat exchanger 122
where cooling is transferred to a load with the aid of an air
handler 150. The warm mixture of liquid and vapor phase refrigerant
leaves the load heat exchanger 122 where the mixture is returned to
the thermal energy storage unit 106 now acting as a condenser.
Vapor phase refrigerant is cooled and condensed by drawing cooling
from the cold fluid or ice. As with the embodiment of FIG. 1, the
principal modes of operation, ice-make, ice-melt and direct cooling
can be performed with the use of a series of valves (not shown)
that control the flow of refrigerant.
[0031] FIG. 4 illustrates an embodiment of a refrigerant-based
thermal energy storage and cooling system with secondary
refrigerant isolation and isolated external melt cooling. As
described in the previous embodiment, the primary refrigerant loop
transfers cooling between the air conditioner unit 102 and the
isolating heat exchanger 162. The thermal energy storage unit 106
operates using the secondary refrigerant loop 103 by receiving
cooled refrigerant from the isolating heat exchanger 162 via the
URMV 146 that acts as a collector and phase separator of the
multi-phase refrigerant. An additional benefit of incorporating a
URMV within the system is that it allows additional application
flexibility with the geometry of the refrigerant lines. This
additional refrigerant reservoir facilitates longer line lengths of
the refrigerant lines, and thus, greater distance tolerances for
locating components.
[0032] The disclosed embodiment also functions in the two modes of
operation, charging and cooling with the addition of a direct
cooling mode. Cooling mode is identical to that of FIG. 3 and
ice-make includes the additional function of the URMV. In charging
mode, the URMV 146 accumulates liquid refrigerant and separates any
vapor phase refrigerant leaving the isolating heat exchanger 162.
Condensed refrigerant leaves the lower portion of the URMV 146 and
is expanded in the primary heat exchanger 160, and cooling is
transferred to the phase change material within the insulated tank
140. Expanded refrigerant leaves the thermal energy storage unit
106 and returns to the upper portion of the URMV where remaining
liquid phase refrigerant is accumulated in the URMV and vapor phase
refrigerant is returned to the isolating heat exchanger 162 for
cooling.
[0033] In direct cooling mode the thermal energy storage unit 106
is bypassed and a by-pass refrigeration loop 107 delivers condensed
refrigerant leaving the air conditioner unit 102 directly to a
primary side of a bypass heat exchanger 198 and is then returned to
the air conditioner unit 102. The secondary side of the bypass heat
exchanger 198 is in communication with the load heat exchanger 122
with the external melt cooling loop 105. Valves 194 and 196 can be
used isolate this loop from the thermal energy storage unit 106,
while additional valves 188 and 189 can be used to remove the
isolating heat exchanger 162 from the primary refrigerant loop 101
and facilitate the by-pass refrigeration loop 107. As with previous
embodiments, a pump 120 is placed in the external melt cooling loop
105 to pump cold liquid phase change material that from secondary
side of the bypass heat exchanger 198 to the load heat exchanger
122 and back. An air handler 150 is utilized in conjunction with
the load heat exchanger 122 to provide cooling to a heat load. This
load heat exchanger 122 may be a single or multiple evaporators
such as might be used to provide multi-zone cooling, mini-split
evaporators or the like.
[0034] Whereas FIGS. 1-3 depict bimodal systems (ice-make and
ice-melt), it is within the scope of the present disclosure that
any of the described embodiments are also adaptable for use of a
direct cooling loop such as described in FIG. 4 with simple
geometric and valve modifications.
[0035] FIG. 5 illustrates a configuration of a refrigerant-based
thermal energy storage and cooling system with secondary
refrigerant isolation and a secondary refrigerant loop 203. As
described in the embodiment of FIG. 1, the primary refrigerant loop
201 transfers cooling between the air conditioner unit 102 and the
thermal energy storage unit 106. During ice-make phase, the thermal
energy storage unit 106 containing the primary heat exchanger 160
acts as a expansion device where expanding refrigerant is fed from
a lower header assembly 156 through the freezing/discharge coils
142, to the upper header assembly 154. Cooling is transmitted from
the freezing coils 142 to the surrounding liquid phase change
material 152 that is confined within the insulated tank 140 and
freezes at least a portion of the phase change material 153 (ice)
surrounding the freezing coils 142 and storing thermal energy in
the process. Warm liquid and vapor phase refrigerant leaves the
freezing coils 142 through the upper header assembly 154 and exits
the thermal energy storage unit 106 returning to the air
conditioner unit 102 through the low pressure return line 118 and
is fed to the compressor 110 and re-condensed into liquid.
[0036] In cooling mode, cool liquid phase change material leaves
the lower portion of the insulated tank 140 and is propelled by a
pump 120 to a primary side of an intermediate heat exchanger 123
where cooling is transferred from the external melt cooling loop
205 to a secondary refrigerant loop 203. Warm liquid leaves the
intermediate heat exchanger 123 and is returned to the upper
portion of the thermal energy storage unit 106 and the warm liquid
draws cooling from the solid phase change material 153 surrounding
the coils. The secondary refrigerant loop 203 flows through the
secondary side of the intermediate heat exchanger 123 drawing
cooling from the fluid on the primary side and warming the liquid
phase change material. This cools and condenses the refrigerant
which is either propelled by a refrigerant pump 121 (as shown) or
driven by a gravity fed thermosiphon (not shown) to a load heat
exchanger 122 where the refrigerant is expanded and cooling is
delivered to a heat load with the aid of an air handler 150. The
warm mixed or vapor phase refrigerant is then returned to the
intermediate heat exchanger 123 to complete the secondary
refrigerant loop 203.
[0037] As with the embodiment of FIG. 2, the embodiment of FIG. 5
may include a URMV, as well as an isolating heat exchanger (as
demonstrated in FIG. 3), a by-pass refrigeration loop and bypass
heat exchanger or any combination thereof as exemplified in FIG.
4.
[0038] By utilizing such an embodiment current dwellings that use
standard air conditioning systems may be readily adapted or
retrofit to a thermal storage system by the addition of a thermal
energy storage unit 106, expansion device 130, Intermediate heat
exchanger 123, pump 120 and refrigerant pump 121. Because the
system isolates the primary refrigerant from a secondary phase
change material loop and a secondary refrigerant, the system
additionally allows the use of a variety of refrigerants to be used
within the device. The disclosed embodiments therefore provide a
refrigerant-based thermal storage system method and device wherein
an isolated external melt cooling loop is utilized to transfer
cooling to a heat load utilizing a phase change material.
[0039] It is also possible to utilize the secondary refrigerant
loop 203 of the embodiment of FIG. 5 as a cooling loop where the
secondary refrigerant is kept in liquid phase throughout its cycle.
This would allow a wide variety of materials to be used to
accomplish the heat transfer between the intermediate heat
exchanger 123 and the load heat exchanger 122. These materials may
include, but are not limited to: water, ammonia, slurry ice, brine,
ethylene glycol, propylene glycol, various alcohols (Isobutyl,
ethanol), sugar, other eutectic materials or the like.
[0040] The foregoing description of the invention has been
presented for purposes of illustration and description. It is not
intended to be exhaustive or to limit the invention to the precise
form disclosed, and other modifications and variations may be
possible in light of the above teachings. The embodiment was chosen
and described in order to best explain the principles of the
invention and its practical application to thereby enable others
skilled in the art to best utilize the invention in various
embodiments and various modifications as are suited to the
particular use contemplated. It is intended that the appended
claims be construed to include other alternative embodiments of the
invention except insofar as limited by the prior art.
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