U.S. patent application number 12/572434 was filed with the patent office on 2011-04-07 for thermal storage device with ice thickness detection and control methods.
This patent application is currently assigned to THERMO KING CORPORATION. Invention is credited to Bernard Wayne Benson, William F. Mohs.
Application Number | 20110079025 12/572434 |
Document ID | / |
Family ID | 43822124 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110079025 |
Kind Code |
A1 |
Mohs; William F. ; et
al. |
April 7, 2011 |
THERMAL STORAGE DEVICE WITH ICE THICKNESS DETECTION AND CONTROL
METHODS
Abstract
A thermal storage device for generating a thermal storage medium
from a fluid and including a storage tank for containing the fluid,
a refrigeration system having a heat exchanger positioned in the
storage tank, a pump for pumping the fluid through the storage
tank, a storage medium detection device, and a controller. The
storage medium detection device generates a signal corresponding to
at least one parameter of the pump. The controller controls the
refrigeration system in one of a first mode and a second mode based
on the signal. The at least one heat exchanger removes heat from
the fluid to generate the thermal storage medium thereon when the
refrigeration system operates in the first mode, and the at least
one heat exchanger does not remove heat from the fluid thereby
terminating generation of the thermal storage medium when the
refrigeration system operates in the second mode.
Inventors: |
Mohs; William F.;
(Minneapolis, MN) ; Benson; Bernard Wayne; (Eden
Prairie, MN) |
Assignee: |
THERMO KING CORPORATION
Minneapolis
MN
|
Family ID: |
43822124 |
Appl. No.: |
12/572434 |
Filed: |
October 2, 2009 |
Current U.S.
Class: |
62/59 ; 62/113;
62/434 |
Current CPC
Class: |
F25D 16/00 20130101;
F25D 17/02 20130101; F25D 11/006 20130101 |
Class at
Publication: |
62/59 ; 62/113;
62/434 |
International
Class: |
F25D 3/02 20060101
F25D003/02; F25B 41/00 20060101 F25B041/00; F25D 17/02 20060101
F25D017/02 |
Claims
1. A method of controlling the generation of a thermal storage
medium from a fluid, the method comprising: positioning at least
one heat exchanger of a refrigeration system within a storage tank
containing the fluid; pumping the fluid with a pump along a flow
path in the storage tank; sensing at least one parameter of the
pump; generating a signal corresponding to the at least one
parameter of the pump; controlling the refrigeration system in one
of a first mode and a second mode based on the signal; operating
the refrigeration system in the first mode to remove heat from the
fluid with the at least one heat exchanger to generate the thermal
storage medium on the at least one heat exchanger; and operating
the refrigeration system in the second mode in which heat is not
removed from the fluid with the at least one heat exchanger, the
second mode for terminating generation of the thermal storage
medium on the at least one heat exchanger.
2. The method of claim 1, further comprising: directing a cooling
fluid of the refrigeration system through one of an evaporator and
a chilling device in the first mode to cool the fluid in the
storage tank.
3. The method of claim 1, wherein generating a signal includes
generating a signal corresponding to a pressure difference across
the pump.
4. The method of claim 1, wherein generating a signal includes
generating a signal corresponding to power consumed by the pump
while pumping the fluid along the flow path.
5. The method of claim 1, further comprising correlating the at
least one parameter to a particular size of the thermal storage
medium.
6. The method of claim 1, wherein positioning at least one heat
exchanger of a refrigeration system within a storage tank includes
staggering a plurality of plates in an alternating fashion within
the storage tank such that the plurality of plates define a
serpentine-shaped path within the storage tank, and wherein pumping
the fluid with a pump along a flow path includes pumping the fluid
with the pump along the serpentine-shaped path.
7. The method of claim 6, wherein staggering a plurality of plates
in an alternating fashion within the storage tank includes
arranging every other of the plurality of plates on a first wall of
the storage tank, and arranging the remaining of the plurality of
plates on a second wall of the storage tank opposite the first
wall.
8. The method of claim 1, wherein operating the refrigeration
system in the second mode includes operating the refrigeration
system in the second mode to prevent the thermal storage medium
from closing the flow path.
9. The method of claim 1, wherein pumping the fluid in the flow
path occurs during the first mode to improve formation of the
thermal storage medium.
10. A thermal storage device for generating a thermal storage
medium from a fluid, the thermal storage device comprising: a
storage tank including first and second ports in fluid
communication with one another defining a flow path through the
storage tank between the first and second ports, the storage tank
configured to contain the fluid; a refrigeration system including
at least one heat exchanger positioned within the fluid in the
storage tank; a pump fluidly coupled to the first and second ports
and operable to pump the fluid through the flow path; a storage
medium detection device operable to generate a signal corresponding
to at least one parameter of the pump; and a controller in
electrical communication with the storage medium detection device
and the refrigeration system, the controller operable to control
the refrigeration system in one of a first mode and a second mode
based on the signal, wherein the at least one heat exchanger
removes heat from the fluid to generate the thermal storage medium
thereon when the refrigeration system operates in the first mode,
and wherein the at least one heat exchanger does not remove heat
from the fluid thereby terminating generation of the thermal
storage medium when the refrigeration system operates in the second
mode.
11. The thermal storage device of claim 10, wherein the at least
one parameter is indicative of a characteristic of the thermal
storage medium.
12. The thermal storage device of claim 11, wherein the
characteristic includes a size of the thermal storage medium.
13. The thermal storage device of claim 10, wherein the at least
one parameter includes a pressure difference across the pump.
14. The thermal storage device of claim 10, wherein the at least
one parameter includes power consumed by the pump while pumping the
fluid through the flow path.
15. The thermal storage device of claim 10, wherein the at least
one heat exchanger includes a plate heat exchanger.
16. The thermal storage device of claim 10, wherein the fluid
includes water and the thermal storage medium includes ice.
17. The thermal storage device of claim 10, wherein the flow path
includes a serpentine-shape.
18. The thermal storage device of claim 10, wherein the
refrigeration system includes a cooling fluid, and wherein the at
least one heat exchanger receives a flow of cooling fluid
therethrough in the first mode to cool the at least one heat
exchanger.
19. The thermal storage device of claim 10, wherein the storage
tank includes a first wall and a second wall opposite the first
wall, wherein the at least one heat exchanger includes a first
plate heat exchanger and a second plate heat exchanger, and wherein
the first plate heat exchanger extends from the first wall and the
second plate heat exchanger extends from the second wall and is
spaced from the first plate heat exchanger such that a
serpentine-shaped path is defined within the storage tank by the
first and second plate heat exchangers, wherein the flow path
includes the serpentine-shaped path.
20. The thermal storage device of claim 10, wherein the storage
medium detection device includes a static pressure switch that
generates the signal corresponding to a rise in pressure across the
pump.
21. The thermal storage device of claim 20, wherein the rise in
pressure across the pump is indicative of a maximum thermal storage
medium thickness.
22. The thermal storage device of claim 10, wherein the pump is
operable to improve formation of the storage medium during the
first mode.
23. A method of controlling the generation of a thermal storage
medium from a fluid, the method comprising: staggering a plurality
of heat exchanger plates in an alternating fashion within a storage
tank containing the fluid such that the plurality of heat exchanger
plates define a serpentine-shaped path within the storage tank;
pumping the fluid with a pump along the serpentine-shaped path in
the storage tank; sensing at least one parameter of the pump,
wherein the at least one parameter of the pump includes at least
one of a pressure difference across the pump and power consumed by
the pump while pumping the fluid along the flow path; generating a
signal corresponding to the at least one parameter of the pump;
correlating the at least one parameter of the pump to a particular
size of the thermal storage medium; controlling the refrigeration
system in one of a first mode and a second mode based on the
signal; operating the refrigeration system in the first mode to
remove heat from the fluid with the at least one heat exchanger to
generate the thermal storage medium on the at least one heat
exchanger; and operating the refrigeration system in the second
mode in which heat is not removed from the fluid with the at least
one heat exchanger, the second mode for terminating generation of
the thermal storage medium on the at least one heat exchanger.
Description
BACKGROUND
[0001] The present invention relates to a thermal storage device,
and in particular to a thermal storage device that utilizes ice as
the storage medium and includes detection methods for determining
ice thickness.
SUMMARY
[0002] In one embodiment the invention provides a method of
controlling the generation of a thermal storage medium from a
fluid. The method includes positioning at least one heat exchanger
of a refrigeration system within a storage tank containing the
fluid, pumping the fluid with a pump along a flow path in the
storage tank, sensing at least one parameter of the pump,
generating a signal corresponding to the at least one parameter of
the pump, controlling the refrigeration system in one of a first
mode and a second mode based on the signal, operating the
refrigeration system in a first mode to remove heat from the fluid
with the at least one heat exchanger to generate the thermal
storage medium on the at least one heat exchanger, and operating
the refrigeration system in a second mode in which heat is not
removed from the fluid with the at least one heat exchanger, the
second mode for terminating generation of the thermal storage
medium on the at least one heat exchanger.
[0003] In another embodiment, the invention provides a thermal
storage device for generating a thermal storage medium from a
fluid. The thermal storage device includes a storage tank, a
refrigeration system, a pump, a storage medium detection device,
and a controller. The storage tank has first and second ports in
fluid communication with one another defining a flow path through
the storage tank between the first and second ports, and is
configured to contain the fluid. The refrigeration system includes
at least one heat exchanger positioned within the fluid in the
storage tank. The pump is fluidly coupled to the first and second
ports and operable to pump the fluid through the flow path. The
storage medium detection device is operable to generate a signal
corresponding to at least one parameter of the pump. The controller
is in electrical communication with the storage medium detection
device and the refrigeration system, and is operable to control the
refrigeration system in one of a first mode and a second mode based
on the signal. The at least one heat exchanger removes heat from
the fluid to generate the thermal storage medium thereon when the
refrigeration system operates in the first mode, and the at least
one heat exchanger does not remove heat from the fluid thereby
terminating generation of the thermal storage medium when the
refrigeration system operates in the second mode.
[0004] Other aspects of the invention will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a schematic cross-sectional view of a thermal
storage device in accordance with the present invention.
[0006] FIG. 2 is a schematic cross-sectional view of the thermal
storage device of FIG. 1 having a buildup of thermal storage
medium.
DETAILED DESCRIPTION
[0007] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways.
[0008] FIGS. 1-2 illustrate a thermal storage device 10 for
generating a thermal storage medium 14 from a fluid 18, such as ice
from water, respectively. The thermal storage device 10 includes a
storage tank 22, a refrigeration system 26, a pump 30, first and
second storage medium detection devices 34a, 34b, and a controller
38. In the illustrated construction, the thermal storage device 10
is used to provide extra cooling capacity during pre-cooling of a
perishable product near a harvesting area to immediately begin
preserving the shelf life of the perishable product. The thermal
storage device 10 is fluidly connected to an appropriately sized
hydrocooler 40, such as an immersion hydrocooler or a spray
hydrocooler. The thermal storage medium 14 is built up during a
non-harvest period, such as overnight. The fluid 18 is cooled by
the thermal storage medium 14 during a use period to cool the
perishable product. The thermal storage device 10 and hydrocooler
40 constitute a modular system that can be transported to various
locations and quickly assembled. In other constructions, other
fluids and thermal storage media may be employed, and the thermal
storage device 10 may be fluidly connected to other devices for
other applications.
[0009] The refrigeration system 26 includes a cooling fluid and a
plurality of plate heat exchangers 50a, 50b receiving a flow of the
cooling fluid therethrough in a first cool mode to cool the heat
exchangers 50a, 50b. It is to be understood that the refrigeration
system 26 includes any suitable type of refrigeration system, such
as, but not limited to, a direct expansion system having an
evaporator or a chilled glycol system having a chilling device.
[0010] The heat exchangers 50a, 50b are positioned within the fluid
18 in the storage tank 22. The storage tank 22 includes a first
wall 54 and a second wall 58 opposite the first wall 54. A first
set of the heat exchangers 50a extends from the first wall 54
substantially perpendicular to the first wall 54 in a cantilevered
fashion such that a gap is left between the first set of heat
exchangers 50a and the second wall 58. A second set of the heat
exchangers 50b extends from the second wall 58 substantially
perpendicular to the second wall 58 in a cantilevered fashion such
that a gap is left between the second set of heat exchangers 50b
and the first wall 54. The tank also includes front and rear walls
(not shown), and the first and second sets of heat exchangers 50a,
50b may extend from the front and rear walls in other
constructions.
[0011] The second set of heat exchangers 50b are spaced from the
first set of heat exchangers 50a in an alternating fashion such
that the gaps alternate and a serpentine-shaped flow path (see
arrows in FIG. 1) is defined within the storage tank 22. In other
constructions, other types of heat exchangers may be employed such
that the thermal storage medium 14 may be built up on surfaces of
the heat exchangers. In yet other constructions, the heat
exchangers 50a, 50b may be arranged in other ways that define other
shapes of flow paths.
[0012] The storage tank 22 contains the fluid 18 and has first and
second ports 42, 46 in fluid communication with one another. The
serpentine-shaped flow path (see arrows in FIG. 1) through the
storage tank 22 extends between the first and second ports 42, 46
from the first port 42 to the second port 46. The pump 30 is
fluidly connected to the first and second ports 42, 46 and operable
to pump the fluid 18 through the flow path to improve formation of
the thermal storage medium 14 during the non-harvest period when
the thermal storage medium 14 is built. During the non-harvest
period, the pump 30 operates to circulate the fluid 18 in a first
circuit, which includes the first port 42, the serpentine-shaped
flow path, and the second port 46. After exiting the second port
46, the pump recirculates the cooling fluid 18 back to the first
port 42. During the use period, the hydrocooler 40 operates to
circulate the fluid 18 in a second circuit, which includes the
first port 42, the serpentine-shaped flow path, the second port 46,
and the hydrocooler 40, which includes an additional pump 66 that
returns the fluid 18 to the first port 42 for recirculation through
the storage tank 22. The second circuit also includes valves 62 for
closing off the second circuit in a closed position and opening the
second circuit in an open position. The valves 62 are closed during
the non-harvesting period and open during the use period.
[0013] The storage medium detection devices 34a, 34b are operable
to generate a signal corresponding to at least one parameter of the
pump 30. In some constructions, only one storage medium detection
device 34a or 34b is employed in the thermal storage device 10.
Both storage medium detection devices 34a, 34b are shown together
in the figures for ease of illustration.
[0014] The first storage medium detection device 34a includes a
pair of pressure sensors positioned upstream and downstream of the
pump 30 to measure a pressure differential across the pump 30. The
pressure differential is indicative of a size of the thermal
storage medium 14, e.g., a thickness of the thermal storage medium
14. The thicker the thermal storage medium 14, the smaller a flow
area in the serpentine-shaped flow path. As the thermal storage
medium 14 increases in thickness, the pressure differential across
the pump 30 increases. When the pressure differential reaches a
predetermined differential, the controller 38 ceases formation of
the thermal storage medium 14.
[0015] The second storage medium detection device 34b includes a
power consumption meter, such as a watt meter, to measure the power
consumption of the pump 30. As the flow area in the
serpentine-shaped flow path decreases, the power consumption of the
pump 30 increases. Thus, an increase in power consumption of the
pump 30 is indicative of increasing thickness of the thermal
storage medium 14. When the power consumption of the pump 30
reaches a predetermined amount, the controller 38 will cease
formation of the thermal storage medium 14.
[0016] The controller 38 is in electrical communication with the
storage medium detection devices 34a, 34b and the refrigeration
system 26, and is operable to control the refrigeration system 26
in one of a first mode and a second mode based on the signal. The
heat exchangers 50a, 50b remove heat from the fluid 18 to generate
the thermal storage medium thereon 14 when the refrigeration system
26 operates in the first mode, and the heat exchangers 50a, 50b do
not remove heat from the fluid 18, thereby terminating generation
of the thermal storage medium 14 when the refrigeration system 26
operates in the second mode. For example, the controller 38 may
cease operation of the refrigeration system 26 and/or operation of
the pump 30.
[0017] In operation, the thermal storage medium 14 is built up
during the non-harvest period, such as overnight, during which
period the refrigeration system 26 operates in the first mode. The
heat exchangers 50a, 50b are cooled by the refrigeration system 26
and the fluid 18 is pumped by the pump 30 along the first circuit
(i.e., the valves 62 are closed) to increase formation of the
thermal storage medium 14 on surfaces of the heat exchangers 50a,
50b in the serpentine-shaped flow path. This stores cooling
potential for future use during high load or peak demand to
minimize the peak demand. Furthermore, this allows a smaller
refrigeration system to be utilized at a high utilization rate
(e.g., all day). If the signal generated by one of the storage
medium detection devices 34a, 34b and received by the controller 38
is indicative of a predetermined thermal storage medium thickness,
the controller 38 ceases formation of the thermal storage medium 18
to prevent the flow path from being completely blocked.
[0018] During the use period, the valves 62 are set to the open
position and the fluid 18 is directed to the thermal storage device
10 where the fluid 18 is cooled by the thermal storage medium 14.
The fluid 18 is then directed to the hydrocooler 40 where the
perishable product is cooled, for example, by immersion or
spraying. The fluid 18 is then collected and redirected back to the
thermal storage device 10 to be re-cooled and re-used for
additional perishable product cooling.
[0019] Thus, the invention provides, among other things, a thermal
storage device for generating a thermal storage medium from a fluid
and a method of controlling the generation of a thermal storage
medium from a fluid. Various features and advantages of the
invention are set forth in the following claims.
* * * * *