U.S. patent application number 10/138310 was filed with the patent office on 2002-11-07 for high performance thermoelectric systems.
Invention is credited to Brown, Jeffrey Russell, Harrison, Howard R..
Application Number | 20020162339 10/138310 |
Document ID | / |
Family ID | 26836082 |
Filed Date | 2002-11-07 |
United States Patent
Application |
20020162339 |
Kind Code |
A1 |
Harrison, Howard R. ; et
al. |
November 7, 2002 |
High performance thermoelectric systems
Abstract
A high performance thermoelectric system is taught which is
capable of rapidly cooling a thermal load with a thermoelectric
module. A thermal ballast is in simultaneous thermal communication
with both the thermoelectric module and the thermal load, and
compensates for the difference between the characteristics of the
thermoelectric module and the demands of the thermal load, allowing
a thermoelectric module to handle significantly larger thermal
loads than would normally be possible, albeit for a reduced period
of time. Also taught is a means to implement a demand cooler for
drinking water. Also taught is a means to implement a high
performance cooler for removable fluid containers, adaptable to the
rapid cooling of wine bottles and the like.
Inventors: |
Harrison, Howard R.;
(Mississauga, CA) ; Brown, Jeffrey Russell;
(Toronto, CA) |
Correspondence
Address: |
HB INNOVATION LTD.
2085 HURONTARIO STREET, SUITE 300
MISSISSAUGA
ON
L5A 4G1
CA
|
Family ID: |
26836082 |
Appl. No.: |
10/138310 |
Filed: |
May 6, 2002 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60288418 |
May 4, 2001 |
|
|
|
Current U.S.
Class: |
62/3.7 ;
62/3.2 |
Current CPC
Class: |
F25B 21/02 20130101;
F25B 2400/24 20130101; F25D 2400/28 20130101; B67D 1/0869 20130101;
F25D 31/002 20130101; H01L 35/30 20130101; F25D 16/00 20130101;
F25D 31/007 20130101; F25D 2331/803 20130101 |
Class at
Publication: |
62/3.7 ;
62/3.2 |
International
Class: |
F25B 021/02 |
Claims
We claim:
1. A high performance thermoelectric system comprising: a. A
thermoelectric module, b. A heat sink, c. A thermal ballast, d. A
thermal load, and e. A thermal conduit. Said thermoelectric module,
said thermal ballast, and said thermal load being in simultaneous
thermal communication through said thermal conduit, said thermal
ballast configured to rapidly absorb heat from said load through
said thermal conduit, said thermoelectric module configured to
simultaneously pump additional heat from said thermal load through
said thermal conduit, said thermoelectric module further configured
to pump said heat from said thermal ballast through said thermal
conduit at a slower rate over time, said thermoelectric module in
thermal communication with said heat sink to disperse said heat and
said additional heat into the ambient air.
2. The high performance thermoelectric system as claimed in claim 1
wherein said thermal conduit may be extended around a cavity to
form a fluid reservoir.
3. The high performance thermoelectric system as claimed in claim 1
further comprising a thermally conductive spacer block between said
thermal conduit and said thermoelectric module, said spacer block
extending through said thermal ballast to be in direct thermal
communication with said thermal conduit.
4. The high performance thermoelectric system as claimed in claim 1
wherein said thermal ballast may be a Phase Change Material with a
characteristic freezing point slightly below the desired
temperature of said thermal load.
5. The high performance thermoelectric system as claimed in claim 1
wherein said thermal ballast may be a Phase Change Material in
liquid or powder format, said Phase Change Material in liquid or
powder format being further contained in a confined space in
thermal communication with said thermal conduit through a thermal
interface, said confined space being configured to position any air
gaps that might form due to the settling of, downward flow of, or
volumetric changes in said Phase Change Material in liquid or
powder format away from said thermal interface.
6. The high performance thermoelectric system as claimed in claim 1
wherein said thermal conduit has thermally conductive protrusions
extending into said thermal ballast.
7. The high performance thermoelectric system as claimed in claim 1
further comprising a second thermal ballast in thermal
communication with said heat sink through a second thermal
conduit.
8. The high performance thermoelectric system as claimed in claim 1
further comprising an auxiliary spacer block, an auxiliary heat
sink, an auxiliary fan, and an auxiliary thermal load, wherein said
auxiliary spacer is in thermal communication with said thermal
conduit, said auxiliary heat sink is in thermal communication with
said auxiliary spacer block, and wherein said auxiliary fan is
adapted to control the flow of heat from said auxiliary load to
said auxiliary heat sink.
9. A flow through demand cooler for fluids comprising: a. A
thermoelectric module, b. A heat sink, c. A thermal ballast, d. A
fluid heat exchanger, and e. A thermal conduit. Said thermoelectric
module, said thermal ballast, and said fluid heat exchanger being
in simultaneous thermal communication through said thermal conduit,
said thermal ballast configured to rapidly absorb heat from said
fluid heat exchanger through said thermal conduit, said
thermoelectric module configured to simultaneously pump additional
heat from said fluid heat exchanger through said thermal conduit,
said thermoelectric module further configured to pump said heat
from said thermal ballast through said thermal conduit at a slower
rate over time, said thermoelectric module in thermal communication
with said heat sink to disperse said heat and said additional heat
into the ambient air.
10. The flow through demand cooler for fluids as claimed in claim 9
wherein said fluid heat exchanger may also be said thermal
conduit.
11. The flow through demand cooler for fluids as claimed in claim 9
further comprising a thermally conductive spacer block between said
thermal conduit and said thermoelectric module, said spacer block
extending through said thermal ballast to be in direct thermal
communication with said thermal conduit.
12. The flow through demand cooler for fluids as claimed in claim 9
wherein said thermal ballast may be a Phase Change Material with a
characteristic freezing point slightly below the desired
temperature of the fluid within said fluid heat exchanger.
13. The flow through demand cooler for fluids as claimed in claim 9
wherein said thermal ballast may be a Phase Change Material in
liquid or powder format, said Phase Change Material in liquid or
powder format being further contained in a confined space in
thermal communication with said thermal conduit through a thermal
interface, said confined space being configured to position any air
gaps that might form due to the settling of, downward flow of, or
volumetric changes in said Phase Change Material in liquid or
powder format away from said thermal interface.
14. The flow through demand cooler for fluids as claimed in claim 9
wherein said thermal conduit has thermally conductive protrusions
extending into said thermal ballast.
15. The flow through demand cooler for fluids as claimed in claim 9
further comprising a second thermal ballast in thermal
communication with said heat sink through a second thermal
conduit.
16. The flow through demand cooler for fluids as claimed in claim 9
wherein said fluid heat exchanger is comprised of a cavity with
vertical or longitudinal partitions, and wherein the fluid within
said fluid heat exchanger must travel around said vertical or
longitudinal partitions in a zigzag pattern.
17. The flow through demand cooler for fluids as claimed in claim 9
wherein said fluid heat exchanger is comprised of an extruded
cavity with sliding longitudinal partitions, said sliding
longitudinal partitions inserted into pre-formed slots within said
extruded cavity, said sliding longitudinal partitions held in place
with a bonding agent, said longitudinal partitions also held in
place by the crimped sides of said pre-formed slots, and wherein
the fluid within said fluid heat exchanger must travel around said
sliding longitudinal partitions in a zigzag pattern.
18. The flow through demand cooler for fluids as claimed in claim 9
further comprising an auxiliary spacer block, an auxiliary heat
sink, an auxiliary fan, and an auxiliary thermal load, wherein said
auxiliary spacer block is in thermal communication with said fluid
heat exchanger, said auxiliary heat sink is in thermal
communication with said auxiliary spacer block, and wherein said
auxiliary fan is adapted to control the flow of heat from said
auxiliary load to said auxiliary heat sink.
19. A high performance cooler for removable fluid containers
comprising; a. A thermoelectric module, b. A heat sink, c. A
thermal ballast, d. A removable fluid container, and e. A thermal
conduit. Said thermoelectric module, said thermal ballast, and said
removable fluid container being in simultaneous thermal
communication through said thermal conduit, said thermal ballast
configured to rapidly absorb heat from said removable fluid
container through said thermal conduit, said thermoelectric module
configured to simultaneously pump additional heat from said
removable fluid container through said thermal conduit, said
thermoelectric module further configured to pump said heat from
said thermal ballast through said thermal conduit at a slower rate
over time, said thermoelectric module in thermal communication with
said heat sink to disperse said heat and said additional heat into
the ambient air.
20. The high performance cooler for removable fluid containers as
claimed in claim 19 wherein said thermal conduit may be in intimate
thermal contact with said removable fluid container, and wherein
said thermal conduit may form a support for said removable fluid
container.
21. The high performance cooler for removable fluid containers as
claimed in claim 19 further comprising a thermally conductive
spacer block between said thermal conduit and said thermoelectric
module, said spacer block extending through said thermal ballast to
be in direct thermal communication with said thermal conduit.
22. The high performance cooler for removable fluid containers as
claimed in claim 19 wherein said thermal ballast may be a Phase
Change Material with a characteristic freezing point slightly below
the desired temperature of fluid within said removable fluid
container.
23. The high performance cooler for removable fluid containers as
claimed in claim 19 wherein said thermal ballast may be a Phase
Change Material in liquid or powder format, said Phase Change
Material in liquid or powder format being further contained in a
confined space in thermal communication with said thermal conduit
through a thermal interface, said confined space being configured
to position any air gaps that might form due to the settling of,
downward flow of, or volumetric changes in said Phase Change
Material in liquid or powder format away from said thermal
interface.
24. The high performance cooler for removable fluid containers as
claimed in claim 19 wherein said thermal conduit has thermally
conductive protrusions extending into said thermal ballast.
25. The high performance cooler for removable fluid containers as
claimed in claim 19 further comprising a second thermal ballast in
thermal communication with said heat sink through a second thermal
conduit.
26. The high performance cooler for removable fluid containers as
claimed in claim 19 wherein said removable fluid container further
contains a fluid and a wine bottle, said wine bottle being immersed
in said fluid, said wine bottle in thermal communication with said
fluid, and said fluid in thermal communication with said thermal
conduit through said removable fluid container.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. patent
application serial No. 60/288,418 filed May 4, 2001, which
application is pending.
FIELD OF THE INVENTION
[0002] This invention relates to an optimized configuration for
high performance thermoelectric systems. A thermal ballast
functions as an auxiliary thermal storage device that is in
simultaneous thermal communication with both the thermoelectric
module and the load, and compensates for the different thermal
characteristics of the thermoelectric module and the load. A
thermal ballast configured in this manner allows a single
thermoelectric module to handle significantly larger thermal loads
than would normally be possible, albeit for a reduced period of
time.
BACKGROUND OF THE INVENTION
[0003] Thermoelectric modules have been around for a number of
years and offer several advantages over compressor based cooling
systems including small size, portability, durability, and
environmental safety. However one significant drawback of these
devices is their relatively low cooling (or heating) rates.
[0004] There have been several attempts to improve the cooling
rates through various thermoelectric module configurations (e.g.
parallel and/or serial configurations), and improved thermoelectric
module technical designs to provide higher heat pumping rates and
higher temperature differentials across the module. Also, designers
have attempted to improve the thermal interfaces between the
thermoelectric module, heat sink, and load to improve the overall
performance of the system. More recent developments include the use
of a thermal battery to store the cold (or lack of heat) or heat
produced by a thermoelectric module, or some other type of cooling
or heating device, for later use.
[0005] U.S. Pat. No. 6,370,884 issued Apr. 16, 2002 to Kelada
teaches a form of high performance thermoelectric system, however
the performance is obtained by deploying a multiple of
thermoelectric devices with one illustration showing a quantity of
eight such devices so deployed. It is doubtful that the large
quantity of heat produced by such a configuration could be
dissipated rapidly enough to maintain the water flowing through the
system at the stated 40F for any length of time. Further, this is
an extremely expensive way to build a high performance
thermoelectric system.
[0006] U.S. Pat. No. 6,247,522 issued Jun. 19, 2001, to Kaplan, et
al, teaches a thermal storage unit designed for the storage and
later use of thermal energy on a larger scale, for example the
later use of energy purchased during low cost off-peak hours.
Energy is transferred to and from the thermal storage unit using a
heat transfer fluid. While this patent suggests the use of phase
change material in the thermal storage unit, it does not address
the use of this material in, nor is it adaptable to, high
performance thermoelectric systems.
[0007] U.S. Pat. No. 6,105,659 issued Aug. 22, 2000 to Pocol, et al
teaches a device for the storage and transfer of thermal energy
with the storage or recharge function being accomplished through
one thermal interface and the further transfer of the stored
thermal energy being accomplished through a second thermal
interface, the configuration being optimized for the transfer of
energy between the device and a gas. This patent focuses on the two
thermal interfaces (e.g. the use of metallic powders that may be
attractively positioned on membrane walls) but does not address
such practical matters as the removal of heat produced by the
thermoelectric heat pump(s) used to recharge the system. The design
is inherently inefficient because it does require two separate
thermal interfaces rather than one, and it does not seem to address
the issues of thermal conductivity within the phase change material
used for energy storage. Further, it does not lend itself to such
common and practical applications as rapidly chilling a quantity of
fluid with a single thermoelectric module.
[0008] U.S. Pat. No. 4,951,481 issued Aug. 28, 1990, to Negishi
(assigned to Sanden Corporation, Japan) teaches a cold preserving
container including a cold accumulator enclosing a cold
regenerative material. The cold regenerative material is cooled by
circulating a cooling medium through an evaporating tube located
between the cold accumulator and the container. This is not
adaptable to high performance thermoelectric systems since it
requires a circulating medium, and the configuration is optimized
for the rapidly cooling the cold accumulator rather than the
container. It is a well-known fact that a thermoelectric module
provides a much slower rate of cooling than a compressor/evaporator
system. The Negishi patent will not provide rapid cooling with a
single thermoelectric module given these constraints.
[0009] The inventors of the subject invention are also the
inventors of U.S. Pat. No. 5,469,708, issued Nov. 28, 1995, and
U.S. Ser. No. 09/522,929, to be issued on or about May 1, 2002, the
disclosures of which are incorporated herein by reference. These
patents describe a water cooler and a combination ice maker and
cooler, respectively, both based on thermoelectric technology.
[0010] It is an objective of the present invention to produce rapid
cooling with a single thermoelectric module, making possible such
devices as a demand cooler for drinking water, a high performance
cooler for removable fluid containers, a rapid chiller for wine
bottles, and several other embodiments not possible given the prior
art. These and other objectives and advantages of the present
invention will become apparent from the reading of the attached
specification and appended claims.
SUMMARY OF THE INVENTION
[0011] The present inventors have optimized the performance of
thermoelectric systems by configuring a thermal ballast as an
auxiliary thermal storage device in order to accommodate the
difference in thermal characteristics between the thermoelectric
module and the load, and to maximize the combined thermal transfer
rates of both the thermal ballast and the thermoelectric module
when a load is present. The thermal ballast, thermoelectric module,
and the load are in simultaneous thermal communication through a
thermal conduit that links the three components together. (The
singular term "thermoelectric module" is understood to represent
one or more thermoelectric modules, as may be required by a
particular application, unless otherwise stated throughout this
document.)
[0012] In most cases thermal loads are intermittent and require a
high rate of heat transfer for a relatively short period of time. A
thermoelectric module, on the other hand, has a substantially
different characteristic since it performs best with a steady
thermal load that requires a relatively low rate of heat transfer.
This relatively low rate of heat transfer determines the maximum
cooling rate in almost all thermoelectric applications. The usual
approach is to leave the thermoelectric module on for an extended
period of time such that the required amount of heat is eventually
removed from the load. This does work, however it takes much longer
than desirable from a user's perspective.
[0013] The present inventors have addressed this problem by
devising a way to configure a thermal ballast, or auxiliary thermal
storage device, such that it is in simultaneous thermal
communication with both the thermoelectric module and the load.
This facilitates the interflow of heat between the thermal ballast,
thermoelectric module, and the load, and allows the thermoelectric
module to be located where it can be configured with an appropriate
heat sink to dissipate heat into the ambient air.
[0014] A thermal ballast is generally a passive component capable
storing either "heat" or "cold" (i.e. the lack of heat). Further, a
thermal ballast may absorb or release heat at various transfer
rates. A maximum heat transfer rate may be achieved by increasing
the surface area of the thermal interface between the thermal
ballast and the load, and by keeping the thermal ballast relatively
thin so as to not encounter limitations related to thermal
conductivity within the thermal ballast itself. In a cooling
application the thermoelectric module may pump heat slowly out of
the thermal ballast until it is fully charged. Then the thermal
ballast is ready to absorb heat very rapidly from the load over a
short space of time. The thermal ballast serves as an auxiliary
thermal storage device that ideally matches the basic
characteristics of both the thermoelectric module and the load.
[0015] It follows that a thermal ballast may satisfy the load
requirements while operating under the constraints of the
thermoelectric module. The intermittent characteristic of the load
means that the imbalance in heat transfer rates will only need to
be supported for a short period of time. This will work providing
that the total heat absorbed by the thermoelectric module from the
thermal ballast substantially equals the total heat absorbed by the
thermal ballast from the load over a given period of time.
[0016] The configuration may be further improved by allowing the
thermoelectric module and the thermal ballast to simultaneously
absorb heat from the load. This contrasts sharply with current
configurations which utilize a thermal battery, rather than a
thermal ballast, configured as a passive "flow through"
component--i.e. the thermoelectric module can only remove heat from
the thermal battery which then in turn can only remove heat from
the load.
[0017] The thermal ballast, thermoelectric module, and the load are
in simultaneous thermal communication through a thermal conduit
that links the three components together. This allows the
thermoelectric module and the thermal ballast to simultaneously
absorb heat from the load, effectively increasing the rate at which
heat may be removed from the load and reducing cooling times
substantially. The same thermal conduit may then be used by the
thermoelectric module to remove heat from the thermal ballast in
preparation for the next load cycle. The thermal conduit allows for
this universal flow of heat between the components as determined by
standard thermodynamic principles.
[0018] A suitable analogy in this case might be a simple savings
account that is used to accumulate funds for an annual vacation.
The cost of the vacation (i.e. the load) is high and intermittent.
On the other hand the savings rate (i.e. the thermoelectric module)
will be slow and steady. The ATM network (i.e. the thermal conduit)
allows the user to maximize vacation spending by accessing the
saved amount (i.e. the thermal ballast) plus any further savings
that might be automatically deposited during this time (additive
effect of thermoelectric module while load is present) Similar to
the thermal system described above, the imbalance in cash transfer
rates only needs to be supported for a short period of time, and
the effect may be to reduce the savings account balance to zero by
the end of the vacation. Then, regular savings will resume to
increase the account balance in time for the next annual
vacation.
[0019] Just as in the case of the savings account, which must be
"sized" to fund the annual vacation, the thermal ballast must be
sized to match the characteristics of the load. Similar to the
savings rate, the heat transfer rate provided by the thermoelectric
module must be sufficient to ensure that the thermal ballast is
prepared for the next load cycle. Whereas the savings account
operates on a cash balance basis, the thermal ballast will operate
on a heat energy balance basis.
[0020] There are several benefits to using a thermal ballast within
a thermoelectric system, including the requirement for a smaller
thermoelectric module, a smaller heat sink, and a smaller (and
quieter) fan. These are significant benefits since one of the major
challenges in thermoelectric design is to quickly and quietly
dissipate the heat produced by the thermoelectric module into the
ambient air. Since a thermoelectric module is a heat pump, the heat
that must be dissipated equals the electrical energy input plus the
heat removed from the load. In other words the heat must be
dissipated at a greater rate than the thermoelectric module's
cooling rate. Thus, a reduction in the cooling requirement by "x"
watts will reduce the heat dissipation requirements by
substantially more than "x" watts.
[0021] The thermal ballast itself may be made of any material that
can store thermal energy, and release it at varying rates. This may
be a solid, a liquid, or some combination thereof. A purely solid
or liquid thermal ballast will store sensible heat, meaning that
the temperature will rise as heat is absorbed or conversely drop as
the heat is removed.
[0022] A combined solid/liquid thermal ballast will also store
thermal energy, however in this case it is stored as latent heat as
the material changes state. This type of thermal ballast may be
made from a specialized Phase Change Material (PCM) that is
designed to change state a very specific temperature.
[0023] A PCM thermal ballast has two important benefits: (1) the
latent heat stored during the change of state is substantially
greater than the sensible heat that may be stored by changing the
temperature within a given state and (2) the change of state occurs
at a constant temperature. The first benefit means that a PCM
thermal ballast may be much smaller and compact than a solid or
liquid thermal ballast. However the second benefit is of particular
importance since thermoelectric systems do not have a great deal of
inherent thermal stability--i.e. the temperatures within the system
tend to fluctuate widely. The addition of a PCM thermal ballast may
stabilize the load temperature at a steady level, and the
thermoelectric module will simply act as a heat pump to transfer
energy out of the PCM thermal ballast at that steady
temperature.
[0024] While not as effective or compact as a PCM thermal ballast,
a solid or liquid thermal ballast may be less expensive in certain
applications. This type of thermal ballast may be implemented by
simply adding thermal gel, water, or a metal such as copper or
aluminium to the existing thermal conduit between the
thermoelectric module and the load. A solid or liquid thermal
ballast may not function at a steady temperature, but it will add
to the thermal stability of the system since a greater amount of
heat transfer will be required to effect a given temperature
change.
[0025] A thermal ballast may also be used on the hot side of a
thermoelectric module to increase the stability of the thermal
system. Thermoelectric modules generally operate with a fixed
temperature differential between the thermal interfaces, and
therefore any change in the hot side temperature also tends to
affect the cold side temperature. Given that hot side temperature
changes are most often caused by changes in the ambient
temperature, it follows that thermoelectric module cold side
temperatures are also affected by ambient conditions. This
sensitivity can be reduced by placing a PCM thermal ballast in
thermal communication with the hot side of the thermoelectric
module and the heat sink in order to keep the hot side temperature
relatively constant as the ambient temperature fluctuates. The
ability to accommodate changes in heat dissipation rates caused by
the now fluctuating differential between hot side and ambient
temperatures is an inherent function of the PCM thermal ballast as
described above.
[0026] While the primary function of a thermal ballast is to act as
an auxiliary thermal storage device, it can also be designed to aid
in the heat transfer process by accommodating differences in the
surface area of components that must be in thermal communication
and/or by accommodating the impact of a variable heat flux over
these surfaces. Thermoelectric modules are generally quite small
with a high but constant heat flux across the thermal
interfaces--i.e. they are capable of pumping a tremendous amount of
heat through a relatively small surface area. Quiet often the
challenge is to collect this heat from a much larger surface area
and "funnel" it through the thermoelectric module. In some
applications this larger surface area has a variable heat
flux--i.e. the heat transferred through the surface varies from
point to point across the surface, and these different heat
transfer rates can fluctuate independently over time. This is, in
fact, one of the major concerns when designing a cooling system for
electronic components such as Intel's Pentium IV processor.
[0027] A thermal ballast is capable of transferring heat at
different rates across its surface, and therefore it is effective
when used in these variable heat flux applications. Further, a PCM
thermal ballast may be used to effectively hold the temperature of
the device constant across the surface regardless of the variations
in heat flux. Finally, a thermal ballast may be designed to
"collect" the heat from a large surface at varying rates, and to
"funnel" the heat into the much smaller thermoelectric module at a
slow but steady rate. The efficiency of this "funnelling" process
may be increased by utilizing a high heat transfer rate dispersion
plate as a thermal conduit between the thermal ballast and the
thermoelectric module, effectively increasing the surface area of
the thermoelectric module.
[0028] A dispersion plate may be used to accommodate for
differences in surface area on both the cold side and the hot side
of a thermoelectric module. Further, the dispersion plate may be
made from a solid piece of material, one or more phase change heat
pipes, a self contained circulation of heat conducting fluid, or
some combination of thereof. On the hot side of the thermoelectric
module, it is possible that the combination of a dispersion plate,
a thermal ballast, and a heat sink with sufficient surface area and
sufficient natural convection characteristics, as might be possible
with some ceramic materials, may be sufficient to preclude the
requirement for a forced convection cooling system. In an efficient
design this type of heat sink could be built into the exterior
surface of the cabinet surrounding the thermoelectric system to
reduce the overall size of the device.
BRIEF DESCRITION OF THE DRAWINGS
[0029] Embodiments of the invention are described by way of example
with reference to the following diagrams in which;
[0030] FIG. 1 provides an overview of a high performance
thermoelectric system with a thermal ballast and a thermal
conduit,
[0031] FIG. 2 is a side section view of a high performance
thermoelectric system designed to rapidly chill a fluid,
[0032] FIG. 3 is a side section view of a demand fluid cooler
utilizing vertical partitions,
[0033] FIG. 4 is a bottom section view of a demand fluid cooler
utilizing longitudinal partitions,
[0034] FIG. 5 is an exploded view of demand fluid cooler heat
exchanger,
[0035] FIG. 6 is a side section view of reservoir fluid cooler with
an auxiliary chilled cabinet,
[0036] FIG. 7 is a partial section view of fluid cooler for
removable fluid bottles,
[0037] FIG. 8 is a partial section view of a rapid chiller for wine
bottles, and
[0038] FIG. 9 is a side section view of a high performance
thermoelectric system with a hot side thermal ballast and a hot
side thermal conduit.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0039] FIG. 1 illustrates a high performance thermoelectric system
1 with thermoelectric module 2, thermal load 6, and thermal ballast
14. The purpose of this system is to remove heat from, or cool,
thermal load 6 and disperse this heat into the ambient air through
heat sink 4. All components except heat sink 4, and the hot side of
thermoelectric module 2, are surrounded by insulation 12 to
substantially prevent the ingress of heat from the warmer ambient
air.
[0040] Thermal conduit 10 facilitates the simultaneous interflow of
heat between thermoelectric module 2, thermal load 6, and thermal
ballast 14. Thermal conduit 10 allows heat from thermal load 6 to
be absorbed rapidly by thermal ballast 14 through a large surface
area of thermal load 6, and then later pumped out of thermal
ballast 14 by thermoelectric module 2 through a much smaller
surface area of spacer block 8. Thermal ballast 14 and thermal
conduit 10 will remain at substantially the same temperature since
they are in direct thermal communication.
[0041] Spacer block 8 allows for the installation of sufficient
insulation 12 between heat sink 4 and thermal conduit 10, such that
heat does not flow directly back from heat sink 4 to thermal
conduit 10. In this application spacer block 8 and thermal conduit
10 may be further integrated to form one composite part in order to
avoid any possible thermal losses in the interface between the two
underlying components.
[0042] Thermoelectric module 2 may initially pump heat from thermal
ballast 14 through thermal conduit 10 and spacer block 8. In a
cooling application thermal ballast 14 acts as an auxiliary thermal
storage device by retaining this absence of heat.
[0043] When thermal ballast 14 is constructed of a solid or liquid
material, the temperature of thermal ballast 14 and thermal conduit
10 will fall as sensible heat is removed from the combined
assembly. The rate at which the temperature of thermal conduit 10
falls will be reduced by the presence of thermal ballast 14 since
more heat must be removed for each degree of temperature change due
to the increased mass of the combined assembly.
[0044] When thermal ballast 14 is made of Phase Change Materials
(PCM), then the temperature of PCM thermal ballast 14 and thermal
conduit 10 will fall to the freezing temperature of the PCM and
remain at that temperature until PCM thermal ballast 14 completely
changes state. The latent heat that must be removed to change the
state of the PCM is substantially greater than the sensible heat
that must be removed to change the temperature of the PCM while it
remains in a single state. Therefore PCM thermal ballast 14 is
capable of storing the absence of a much greater amount of heat
than a solid or liquid thermal ballast 14.
[0045] The freezing point of PCM thermal ballast 14 may be selected
to be somewhat below the desired temperature of thermal load 6 such
that a thermal gradient will exist between thermal load 6 and
thermal ballast 14, encouraging the natural flow of heat from the
former to the latter through thermal conduit 10. Note that the
freezing point of PCM thermal ballast 14 may be any temperature
within a very wide range, and does not necessarily mean the
freezing point of water or the temperature at which ice forms. The
freezing point of PCM thermal ballast 14 is the temperature at
which the material within PCM thermal ballast 14 changes state from
liquid to solid.
[0046] During normal operation thermoelectric module 2 may be
turned on before thermal load 6 is applied to the system, and will
continue to operate until the temperature of thermal ballast 14 and
thermal conduit 10 reaches a preset value. In the case of a PCM
thermal ballast 14, this preset value may be set at a temperature
somewhat below the PCM freezing point, ensuring that the PCM has
completely changed state and that a maximum amount of heat has been
removed from PCM thermal ballast 14 before thermoelectric module 2
is turned off again.
[0047] Thermal load 6, when introduced to the system, may be at a
much higher temperature than thermal ballast 14 and thermal conduit
10. Thermal ballast 14 will immediately begin to absorb heat from
thermal load 6, through thermal conduit 10. The temperature of
thermal load 6 will drop more rapidly than possible with only
thermoelectric module 6 because thermal ballast 14 is able to
absorb heat much more rapidly than possible with a thermoelectric
heat pump.
[0048] In the case of PCM thermal ballast, the temperature of PCM
thermal ballast 14 will remain at the PCM freezing point as heat is
being rapidly absorbed from thermal load 6 unless the net amount of
heat absorbed by PCM thermal ballast 14 exceeds the latent heat
required to melt the PCM contained within PCM thermal ballast 14.
This is an extremely important feature of a PCM thermal ballast
since it means that an optimum temperature gradient will always
exist between thermal load 6 and thermal ballast 14, ensuring that
heat from thermal load 6 will be absorbed by thermal ballast 14 at
a maximum rate.
[0049] The heat absorbed by thermal ballast 14 will cause its
temperature to rise, further causing the power to be applied to
thermoelectric module 2 by a control circuit. In the case of a PCM
thermal ballast 14 the temperature will initially rise to the
freezing point of the PCM material, and then remain at that point
as the PCM material absorbs heat and begins to melt. The control
circuit will sense this initial rise in temperature, and cause
power to be applied to thermoelectric module 2, since the preset
value for turning off thermoelectric module 2 may be set at a
temperature just below the PCM freezing point as described in a
previous paragraph.
[0050] Thermoelectric module 2 will then be turned on again to
simultaneously pump additional heat from thermal load 6, through
thermal conduit 10 and spacer block 8, and out through heat sink 4
to be dispersed into the ambient air using natural and/or forced
convection. This will further increase the rate of cooling of
thermal load 6 beyond that possible with only thermal ballast 14.
This combined cooling effect is possible since thermal load 6,
thermoelectric module 2, and thermal ballast 14 are in simultaneous
thermal communication through thermal conduit 10.
[0051] Thermoelectric module 2 will continue to pump heat from
thermal load 6 until such time as thermal load 6 and thermal
ballast 14 are in thermal equilibrium. Then, thermoelectric module
2 will remain on to continue to pump heat from thermal load 6 and
thermal ballast 14 until a set point is reached, indicating that
thermal load 6 has reached its target temperature and that a
maximum amount of heat has been removed from thermal ballast
14--i.e. that the system is completely prepared for a next thermal
load 6. In the case of a solid or liquid thermal ballast, this set
point may be determined by sensing the temperature of thermal
ballast 14 and thermal conduit 10 at a value somewhat below the
desired temperature of thermal load 6. In the case of a PCM thermal
ballast 14, the steady state temperature of thermal load 6 will be
closely linked to the fixed PCM freezing point, and the set-point
may be determined by sensing a temperature of PCM thermal ballast
14 that is somewhat below the PCM freezing point.
[0052] A variable temperature control may be more easily
implemented with a solid or liquid thermal ballast 14 because of
the direct relationship between sensible heat and temperature,
however performance will not match that of a PCM thermal ballast
14. It is possible to implement a variable temperature control with
a PCM thermal ballast 14, however this is best suited to a variance
of set points at or below the inherent set point based on the PCM
freezing point. This is because a PCM thermal ballast 14 will act
as a PCM thermal ballast 14 until frozen, and then it will act as a
solid thermal ballast 14 and be responsive to sensible heat. A set
point which is above the inherent set point (based on the PCM
freezing point) would not allow the system to take advantage of the
large latent heat absorption capabilities of the PCM material at
its freezing point. Alternate strategies for variable set points
may include the use of multiple PCM thermal ballasts having various
freezing points within the required range of set-point
temperatures. In this case the multiple PCM thermal ballasts would
also be capable of storing a greater total amount of latent heat,
contributing to the overall performance of the system.
[0053] FIG. 2 is a side view of a high performance thermoelectric
system designed to rapidly chill a fluid flowing through fluid
chamber 20 having inlet 22 and outlet 24. Thermal conduit 10 may be
in thermal communication with thermal ballast 14, and with
thermoelectric module 2 through spacer block 8. In this case spacer
block 8 has been extended to create a greater space between
thermoelectric module 2 and thermal conduit 10, allowing thermal
ballast 14 to be located in this area. Thermal ballast 14, spacer
block 8, and thermal conduit 10, containing fluid chamber 20, may
be surrounded by insulation 12 to substantially prevent the
absorption of heat from the surrounding air.
[0054] The thermal communication between thermal conduit 10 and
thermal ballast 14 may be improved through the use of thermal fins
11. Ultimately, thermal fins 11 improve the rate at which thermal
ballast 14 may absorb heat from the load, in this case the fluid
within fluid chamber 20.
[0055] Of note is the fact that thermal ballast 14 may be comprised
of a PCM in a powder or liquid format. These types of PCM will
naturally tend to flow or settle down against thermal barrier 10
and thermal fins 11 when the high performance thermoelectric
cooling system is in the illustrated orientation, and this will
ensure the best possible thermal interface between thermal ballast
14 and thermal conduit 10. Air gap 15 will naturally form at the
top of thermal ballast 14 as a powder based PCM settles down, or as
a liquid based PCM flows down and/or changes volume during a change
of state. This will not affect system performance since air gap 15
forms between thermal ballast 14 and insulation 12 (i.e. not
between thermal ballast 14 and thermal conduit 10).
[0056] It follows that the high performance thermoelectric cooling
system in FIG. 2 will function best in the orientation shown with
thermoelectric module 2 at the top of the system. The system will
also function well with the same component configuration and with
thermoelectric module 2 at any side of the system since air gap 15
would then form at either end of thermal ballast 14, perhaps
exposing a small portion of thermal conduit 10 to air but otherwise
not substantially affecting system performance. However the
thermoelectric system in FIG. 2 will not function well with
thermoelectric module 2 at the bottom of the system since air gap
15 would then form between thermal ballast 14 and thermal conduit
10, substantially reducing thermal communication between these two
components.
[0057] The thermal communication between thermal conduit 10 and the
fluid contained within fluid chamber 20 may be improved by
extending thermal conduit 10 such that it surrounds fluid chamber
20 on all sides, thereby establishing maximum thermal contact
between thermal conduit 10 and the fluid within fluid chamber 20.
This thermal contact may be further improved by pressurizing the
fluid within fluid chamber 20, and ensuring that there are no gas
bubbles trapped within the system that might form a gap between the
fluid within fluid chamber 20 and any part of thermal conduit
10.
[0058] The system may be used to rapidly chill a fluid flowing
through fluid chamber 20 by first using thermoelectric module 2 to
pump as much heat as possible from thermal ballast 14 through
thermal conduit 10 and spacer block 8. In the case of a PCM thermal
ballast 14, thermoelectric module 2 must pump all of the latent
heat from the PCM material in order to ensure that it is completely
frozen. This process may take place over an extended period of time
based on the relatively slow heat pumping capacity of
thermoelectric module 2.
[0059] Once thermal ballast 14 is prepared in this manner, fluid
may be allowed to flow into fluid chamber 20. Thermal ballast 14
rapidly absorbs heat from the fluid through thermal conduit 10,
extended to form the walls of fluid chamber 20. Thermoelectric
module 2 may also absorb heat from the fluid through thermal
conduit 10, albeit at a much slower rate. As a result the
temperature of the fluid within fluid chamber 20 will drop more
rapidly than possible with only thermoelectric module 2 or thermal
ballast 14.
[0060] The freezing point of the PCM material contained in thermal
ballast 14 may be selected to be substantially below the desired
temperature of the fluid leaving fluid chamber 20 in order to
establish a wide temperature differential between the two, thus
encouraging the rapid flow of heat between the two. However the PCM
freezing point must be above the freezing point of the fluid so
that any fluid remaining in fluid chamber 20 will not become frozen
and block the further flow of fluid through fluid chamber 20. If
the fluid is water, then the PCM freezing point must be above 0 C.
(32 F.) to prevent the formation of ice within fluid chamber
20.
[0061] In the case of a PCM thermal ballast, the temperature of PCM
ballast 14 will remain constant unless the net amount of heat
absorbed by thermal ballast 14 (i.e. the heat absorbed from the
fluid in fluid chamber 20 minus the heat pumped out by
thermoelectric module 2) exceeds the latent heat required to melt
the PCM contained within PCM thermal ballast 14. The latent thermal
capacity of PCM thermal ballast 14 and the heat pumping capacity of
thermoelectric module 2 may be designed to ensure that the
temperature of PCM thermal ballast 14 does remain constant for a
given total fluid flow through fluid chamber 20. Further, the heat
pumping capacity of thermoelectric module 2 may be designed to
ensure that all of the latent heat within PCM thermal ballast 14 is
removed prior to the next requirement for chilled fluid.
[0062] The temperature of any fluid remaining in fluid chamber 20
between uses will eventually approach that of thermal ballast 14.
This temperature will be below the required chilled fluid
temperature because the fluid is not flowing through fluid chamber
20. In some cases this may be undesirable since the first fluid
leaving the system at outlet 24 will be much colder than
normal.
[0063] The initial "plug" of colder than normal fluid in fluid
chamber 20 may be mixed with warmer fluid flowing through fluid
bypass 26 to achieve the desired fluid temperature at outlet 24 as
controlled by fluid mixing valve 28. Besides preventing a
potentially undesirable situation, this process actually improves
the efficiency of the system by taking advantage of the excess
sensible heat that has been removed from the fluid remaining in
fluid chamber 20 between uses. Fluid mixing valve 28 may also be
used to facilitate temperature control by providing a range of
warmer than normal fluid temperatures at outlet 24.
[0064] The contact surface area between fluid chamber 20 and
thermal conduit 10 may be designed to achieve the required heat
transfer rate between the fluid flowing through fluid chamber 20
and the combined heat absorption capabilities of thermal ballast 14
and thermoelectric module 2. The required heat transfer rate is
dependent upon (1) the temperature of fluid entering fluid chamber
20, (2) the required temperature drop as the fluid flows through
fluid chamber 20, (3) the fluid flow rate through fluid chamber 20,
(4) the contact area between the fluid and thermal conduit 10, (5)
the steady state temperature of thermal ballast 14 (i.e. the PCM
freezing temperature), (6) the specific heat of the fluid, and
other design parameters. Once established, the heat transfer rate
between the fluid in fluid chamber 20 and thermal conduit 10 will
remain relatively the same for as long as the underlying
parameters, including the temperature of thermal ballast 14, remain
constant.
[0065] FIG. 3 depicts a configuration that substantially increases
the contact area between the fluid within fluid chamber 20 and
thermal conduit 10, thereby allowing for a greater flow of fluid
through fluid chamber 10, providing that the combined capacity of
thermal ballast 14 and thermoelectric module meets the increased
heat absorption requirements. If designed correctly, this
configuration may be used to chill a fluid to a desired temperature
as it flows through the system, i.e. it may be used to chill a
fluid on demand.
[0066] Flow through chamber 21 may be comprised of down flow
channels 23 and up flow channels 25. Fluid flowing into inlet 22
must first flow along down flow channel 23, and then along up flow
channel 25, and so on before exiting at outlet 24. The fluid
flowing along this extended path is in greater thermal contact with
thermal conduit 10, now extended through vertical thermal
partitions 27, allowing thermal conduit 10 to absorb a
substantially greater amount of heat from the fluid flowing in this
manner. Fluid remaining in flow through channel 21 after flow has
stopped will eventually reach the set-point temperature of thermal
ballast 14, as previously described, and may be mixed with warmer
water flowing through fluid bypass 26 to achieve the desired fluid
temperature at outlet 24 as controlled by fluid mixing valve 28,
again as previously described.
[0067] FIG. 4 provides a bottom cross sectional view of a demand
fluid chiller that may be used to chill a quantity of fluid to a
required temperature as it flows through longitudinal flow chamber
29. Fluid enters the system through inlet 22, then flows in a first
direction as indicated by forward flow arrow 35, then flows in a
second direction as indicated by backward flow arrow 33, then
repeats this process until it exist through outlet 24. Longitudinal
flow chamber 29 may be defined as having a length equal to the
total length of all longitudinal sections as separated by
longitudinal thermal partitions 31.
[0068] As this is a bottom cross sectional view, thermal conduit 10
extends up and over the top of longitudinal thermal partitions 31.
Thermal conduit 10 is in direct thermal communication with
longitudinal thermal partitions 31, and is ideally formed of the
same material as longitudinal thermal partitions 31 as indicated in
FIG. 4. Spacer block 8, thermoelectric module 2, and heat sink 4
are all located above thermal conduit 10 and therefore appear as
hidden lines in FIG. 4. The chilled components are surrounded by
insulation 12 as in previous examples.
[0069] Thermal ballast 14 (reference FIG. 3) is not shown in FIG. 4
for clarity, however it is a necessary system component and must be
present for the system to function properly. It should be noted,
however, that the system will not function efficiently in the
upside down position depicted in FIG. 4 since this orientation may
cause air gap 15 to form between thermal ballast 14 and thermal
conduit 10 (reference FIG. 3).
[0070] This configuration substantially increases the contact area
between the fluid flowing through longitudinal flow chamber 29 and
thermal conduit 10 as well as the duration of time that the fluid
spends in longitudinal flow chamber 29 as it flows through
longitudinal flow chamber 29, thereby allowing for a greater
reduction in the temperature of the fluid as it flows through the
system--providing that the combined capacity of thermal ballast 14
and thermoelectric module 2 meets the increased heat absorption
requirements. This configuration may be used to build a demand
water cooler for drinking water using a single thermoelectric
module 2 and a sufficient quantity of thermal ballast 14 (reference
FIG. 3).
[0071] This configuration further enhances thermal communication
between the fluid flowing through longitudinal flow chamber 29 and
the large top and bottom sections of thermal conduit 10 since the
fluid is in constant contact with the large top and bottom sections
of thermal conduit 10. In particular, the fluid is in constant
contact with the main body of thermal conduit 10, i.e. the large
top part of thermal conduit 10 that lies closest to thermal ballast
14 and thermoelectric module 2 (reference FIG. 3). For these
reasons longitudinal thermal partitions 31 may be made of
substantially thinner material than the large top and bottom
portions and sides of thermal conduit 10 since their primary
function is the containment of fluid flow rather than thermal
conductivity.
[0072] A plurality of longitudinal thermal partitions 31, of thin
format as described above, may be used to maximize the total length
of longitudinal flow channel 29, therefore optimizing the thermal
contact, including surface area and duration, between the fluid
flowing through longitudinal flow channel 29 and thermal conduit
10. Ultimately this will maximize the amount of heat that may be
absorbed by thermal conduit 10 from the fluid, further reducing the
temperature of the fluid and increasing the effectiveness of the
demand chiller.
[0073] FIG. 5 illustrates a method whereby longitudinal flow
channel 29 (reference FIG. 4) may be constructed from extruded
thermal conduit 41, inserted thermal partitions 43, and end caps
45. Extruded thermal conduit 41 is first formed as a hollow
extrusion with longitudinal grooves 47a, 47b, 47c, and 47d using
standard extruding techniques.
[0074] Thermal partitions 43a, 43b, 43c, and 43d are independently
formed having a length less than the length of extruded thermal
conduit 41 so as to allow the flow of fluid past one end or the
other after being inserted into extruded thermal conduit 41.
Thermal partitions 43a, 43b, 43c, and 43d are ideally made from
thermally conductive material.
[0075] A first thermal partition 43a may be inserted into
longitudinal groove 47a as indicated by insertion arrow 49 until
the rear edge of thermal partition 43a is flush with the rear edge
of extruded thermal conduit 41. Then, a second thermal partition
43b may be inserted into longitudinal groove 47b, however in this
case it must be inserted until the front edge of thermal partition
43b is flush with the front edge of extruded thermal conduit 41. It
follows that thermal partition 47c must be inserted until the rear
edge is flush, and that thermal partition 47d must be inserted
until the front edge is flush in an alternating pattern so as to
create the required longitudinal flow chamber 29 as depicted in
FIG. 4.
[0076] Thermal partitions may be press fit, bonded in place with an
adhesive, or crimped in place by forcing the sides of each
longitudinal grooves 47a, 47b, 47c, and 47d against the respective
thermal partitions, once inserted. The crimping process may be
conveniently completed by forcing a slightly oversized tool between
the thermal partitions such that the sides of the longitudinal
grooves are forced outward against the partitions, thereby holding
the partitions in place.
[0077] End caps 45a and 45b may be affixed with using machine
screws or some other convenient method, and sealed with gaskets 51a
and 52b respectively, to complete the construction process and form
longitudinal flow chamber 29 (reference FIG. 4). Alternatively end
caps 45a and 45b may be welded in place. Finally, fixtures for
inlet 22 and outlet 24 may be added at either end of longitudinal
flow chamber 29 (reference FIG. 4).
[0078] Thermal interface area 53 may be lapped on the top surface
of extruded thermal conduit 41 to facilitate the thermal interface
between extruded thermal conduit 41 and spacer block 8 (reference
FIG. 2). Thermal ballast 14 (reference FIG. 2) may also be added to
the top surface of extruded thermal conduit 41 as previously
described.
[0079] FIG. 6 is a side view of a high performance thermoelectric
cooling system with two loads. This system is designed to improve
the performance of a chilled water reservoir, and to provide the
supplementary capability to further chill an area proximal to the
chilled water reservoir.
[0080] Chilled reservoir 30 is typical of many water coolers where
a small amount of water is allowed to drain into, or is pumped
into, a reservoir, which is then chilled by a thermoelectric or
compressor based cooling system. The chilled water is then
dispensed, allowing additional warm water to enter the reservoir.
One of the characteristic problems with this configuration,
especially when a thermoelectric cooler is used, is the amount of
time taken to chill the next "batch" of water, particularly after
the entire reservoir has been drained of chilled water.
[0081] The performance of chilled water reservoir 30 may be
improved with the addition of thermal conduit 10 and thermal
ballast 14. Thermal ballast 14, the first load, i.e. the water
within chilled reservoir 30, and thermoelectric module 2 are in
thermal communication through thermal conduit 10. Thermoelectric
module 2 may simultaneously pump heat from the fluid contained
within chilled reservoir 30 and thermal ballast 14 through thermal
conduit 10 and spacer block 8. In the case of a PCM thermal ballast
14, thermoelectric module 2 will pump all of the latent heat from
PCM thermal ballast 14 such that the material contained therein
becomes completely frozen. The freezing point of a PCM thermal
ballast 14 may be selected to be slightly below that of the desired
fluid temperature within chilled reservoir 30, but not to the
extent that this fluid could itself become frozen.
[0082] Warm fluid will enter chilled reservoir 30 through inlet 32
in response to the dispensing of chilled fluid through outlet 34.
Heat from this warm fluid is immediately absorbed by thermal
ballast 14, which acts as an intermediate heat sink to reduce the
temperature of the fluid much more rapidly than would normally be
possible with only thermoelectric module 2. The heat absorbed by
thermal ballast 14 is then pumped out by thermoelectric module 2
and dissipated through heat sink 4 over time. In the case of a PCM
thermal ballast 14, the temperature of reservoir 30 will remain
much more constant as governed by the characteristic freezing
temperature of the PCM material. Also, a much smaller PCM thermal
ballast may be used since the latent heat absorbed per unit volume
is substantially greater than the sensible heat that could be
absorbed by a solid or liquid thermal ballast having the same unit
volume of material.
[0083] In some cooler designs it may be desirable to simultaneously
cool a food storage area 38 and chilled reservoir 30 with a single
thermoelectric module 2. Auxiliary heat sink 42 may also be in
thermal communication with thermal conduit 10 through auxiliary
spacer block 44. Alternatively, auxiliary heat sink 42 may be in
thermal communication with thermal conduit 10 through a heat pipe
or any other means as may be required to provide the desired
thermal characteristics over the required distance.
[0084] In this case thermal ballast 14, a first load, i.e. the
water within chilled reservoir 30, a second auxiliary load,
represented by auxiliary heat sink 42, and thermoelectric module 2
are in thermal communication through thermal conduit 10.
[0085] Auxiliary heat sink 42 may absorb heat from food storage
area 38 slowly through natural convection or more quickly through
forced convection by turning on auxiliary fan 40. The rate of heat
absorption may be further controlled by controlling the speed of
auxiliary fan 40. In this manner auxiliary heat sink 42 presents a
steady state auxiliary load on thermoelectric module 2 when
auxiliary fan 40 is off (i.e. natural convection) and an increased
controllable load on thermoelectric module 2 and thermal ballast 14
when auxiliary fan 40 is on (i.e. forced convection).
Thermoelectric module 2 must be specified to manage at least this
incremental auxiliary load in addition to the thermal loads
presented by reservoir 30.
[0086] Auxiliary fan 40 may be left off at all times except when
the controller has determined that the fluid within reservoir 30 is
at the correct chilled temperature and that all of the sensible and
latent heat has been removed from thermal ballast 14. This
condition indicates that the reservoir is ready to dispense chilled
fluid and that thermal ballast 14 is conditioned to absorb a
maximum amount of heat when warm fluid enters chilled reservoir 30
to replace the dispensed chilled fluid. At that time auxiliary fan
40 may be turned on to allow auxiliary heat sink 42 to absorb heat
at a greater rate from food storage area 38 such that this heat may
be further absorbed by thermal ballast 14. This will cause the
controller to again turn on thermoelectric module 2 so that this
incremental heat, originally from food storage area 38, may be
pumped from thermal ballast 14 and dispersed into the ambient air
through heat sink 4. This process will continue until such time as
auxiliary fan 40 is turned off, i.e. when food storage area 38 has
reached its target temperature or when additional cooling is
required in reservoir 30 as a result of chilled fluid being
dispensed through outlet 34.
[0087] FIG. 7 is a side view of high performance thermoelectric
cooler with a cold saddle 48 in intimate thermal contact with a
removable fluid container 46. Cold saddle 48 is a specialized type
of thermal conduit that has been formed to mate with removable
fluid container 46 over a large surface area in order to provide
intimate thermal contact with removable fluid container 46, and
also to support removable fluid container 46. Cold saddle 48 may be
constructed of any rigid material of suitable thermal conductivity,
or any flexible material of suitable thermal conductivity in order
to adapt to different removable container 46 geometries. The load,
represented by removable fluid container 46, thermal ballast 14,
and thermoelectric module 2 are in thermal communication through
the thermal conduit which is, in this case, cold saddle 48.
[0088] Removable fluid container 46, as shown in FIG. 7, is a
partial view of an inverted standard 3.0 or 5.0 gallon removable
fluid container. It should be noted that the principles taught here
may be universally applied to any removable fluid container 46
whether in an upright, sideways, inverted or any other physical
orientation.
[0089] Thermoelectric module 2 pumps heat from the fluid contained
in removable fluid container 46, through cold saddle 48 and spacer
block 8, and into heat sink 4 where it may be dispersed into the
ambient air. Removable fluid container 46 is typically housed
within an insulated container such that the entire bottle of fluid
may be efficiently chilled.
[0090] Thermoelectric module 2 may simultaneously pump heat from
thermal ballast 14 through cold saddle 48. In the case of a PCM
thermal ballast 14, a large amount of latent heat may be pumped
from PCM thermal ballast 14 at the characteristic freezing point of
the phase change material. This freezing point should be selected
to be slightly below the desired water temperature, but not to the
extent that it would cause the fluid to freeze. Thermoelectric
module 2 may be turned off when the water has reached the desired
temperature and all of the latent heat has been removed from PCM
thermal ballast 14.
[0091] At such time as a new removable fluid container 46 is placed
in the system, thermal ballast 14 will immediately absorb heat from
the fluid contained therein at a rate that is faster than would
normally be possible with only thermoelectric module 2. As a
result, the temperature of the water will drop faster than would
normally be possible with only thermoelectric module 2. This
addresses one of the characteristic problems of a thermoelectric
water cooler, that being the cool down rate of a new removable
fluid container 46, and effectively increases the performance of
the overall system.
[0092] FIG. 8 illustrates a high performance thermoelectric cooler
that may be adapted to rapidly chill various sizes of wine bottles,
water bottles, and the like. In this case fluid container 46 may be
an open container, containing water or some other liquid that may
further surround and provide intimate thermal contact with wine
bottle 49, and sized to accommodate the largest anticipated wine
bottle 49. Fluid container 46 may be designed to provide intimate
thermal contact with cold saddle 48 as in the previous example, and
may be removed for serving and for cleaning purposes. Further,
fluid container 46 may be constructed of thermally conductive
material to facilitate the rapid transfer of heat through its
walls. Insulation 12 may be extended to provide an insulated area
above cold saddle 48 such that multiple bottles may be stored above
cold saddle 48, with or without fluid container 46 in place.
[0093] Thermoelectric module 2 pumps heat from the fluid contained
within removable fluid container 46, through cold saddle 48 and
spacer block 8, and into heat sink 4 where it may be dispersed into
the ambient air. Thermoelectric module 2 may simultaneously pump
heat from thermal ballast 14 through cold saddle 48. In the case of
a PCM thermal ballast 14, a large amount of latent heat may be
pumped from PCM thermal ballast 14 at the characteristic freezing
point of the phase change material. This freezing point should be
selected to be slightly below the desired water temperature, but
not to the extent that it would cause the fluid to freeze.
Thermoelectric module 2 may be turned off when the water has
reached the desired temperature and all of the latent heat has been
removed from PCM thermal ballast 14.
[0094] At such time as wine bottle 49 is introduced to the system,
the fluid in removable fluid container 46 will immediately begin to
absorb heat from wine bottle 49, and the temperature of the fluid
will begin to rise. Thermal ballast 14 will then absorb heat from
the fluid at a rate that is faster than would normally be possible
with only thermoelectric module 2, keeping the temperature of the
fluid at a low level where it may continue to absorb heat from wine
bottle 49. As a combined result, the temperature of wine bottle 49
will drop faster than would normally be possible with only
thermoelectric module 2. It should be noted that in this case the
fluid contained within removable fluid container 46 acts as a type
of intermediate thermal ballast to directly absorb heat from wine
bottle 49 and add to the temperature stability of the system.
[0095] Thermal ballast 14 has the ability to absorb heat at
different rates across its surface. This will contribute to the
performance of the system since the temperature of removable fluid
container 46 will be varied in this application. The temperature of
wine bottle 49 will be warmer than that of the fluid contained
within removable fluid container 46 when wine bottle 49 is first
introduced to the system, and this will cause the temperature of
removable fluid container 46 to rise in the area where it contacts
wine bottle 49. This will cause thermal ballast 14 to more rapidly
absorb heat through cold saddle 48 in this area of direct contact.
Thermal ballast 14 may be of thicker depth under the bottom of cold
saddle 48 to take advantage of this characteristic and contribute
to the overall performance of the system.
[0096] FIG. 9 illustrates the use of a hot side thermal ballast 92
to improve the capabilities of the high performance thermoelectric
system first presented in FIG. 2. Thermoelectric module 2 operates
on a fixed temperature differential between cold and hot sides, as
is characteristic of all thermoelectric modules. As a consequence,
any increase in the hot side temperature will also increase the
cold side temperature, negatively impacting the thermoelectric
modules ability to pump heat from the load. The temperature of heat
sink 4 is closely related to the hot side temperature of
thermoelectric module 2. It follows that a stable heat sink 4
temperature will contribute to the overall stability of the high
performance thermoelectric system.
[0097] Heat sink 4 has been extended to form hot side thermal
conduit 90. This may be accomplished using standard extruding
techniques, or by affixing hot side thermal conduit 90 such that it
is in thermal communication with heat sink 4.
[0098] Hot side thermal ballast 92 may be in hot side thermal
conduit 90 as shown. Should hot side thermal ballast 92 include a
PCM, the PCM may be selected to have a characteristic melt point
that equals the desired stable temperature for heat sink 4. PCM hot
side thermal ballast 92 will then be able to absorb a maximum
amount of latent heat at this temperature, and contribute to the
overall temperature stability of the system. Hot side air gap 94
may form as PCM hot side thermal ballast 92 settles downwards in
the case of a powder, or flows downwards in the case of a liquid.
Hot side air gap 94 will have a minimal affect on the thermal
communication between PCM hot side thermal ballast 92 and hot side
thermal conduit 90 since it is formed on the top rather than the
bottom surface of PCM hot side thermal ballast 92.
[0099] Thermoelectric module 2 is in simultaneous thermal
communication with heat sink 4 and hot side thermal ballast 92
through hot side thermal conduit 90. A sudden increase in the
amount of heat pumped by thermoelectric module 2, perhaps due to
the introduction of a load within fluid chamber 20, would normally
cause the temperature of heat sink 4 to rise. However in this
configuration the sudden increase in the amount of heat pumped by
thermoelectric module 2 may be first absorbed by hot side thermal
ballast 92. Then, this heat may be dispersed through heat sink 4
and into the ambient air, at a slower rate over time and without
substantially affecting the temperature of heat sink 4. Normal
operation of thermoelectric module 2 may continue throughout this
process since heat sink 4 may simultaneously disperse heat from
thermoelectric module 2 and hot side thermal ballast 92 as
delivered to heat sink 4 through hot side thermal conduit 90.
[0100] Cooling fan 96 may be added to the high performance
thermoelectric system to increase the rate at which heat may be
dispersed from heat sink 4 and into the ambient air. This will be
particularly important for systems using hot side thermal ballast
92 since the heat contained therein must also be dispersed into the
ambient air. Cooling fan 96 may be left on during a thermoelectric
module 2 "off" cycle to ensure that this heat is fully dissipated
prior to the next thermoelectric module 2 "on" cycle.
[0101] It should also be noted that the performance of all high
performance thermoelectric systems may be further improved by
implementing thermal persist technology as first introduced by the
present inventors as part of U.S. utility patent application Ser.
No. 09/522,929. This teaches that a small forward voltage may be
left on the thermoelectric module during what would normally be the
"off" cycle to prevent the reverse flow of heat back through the
thermoelectric module during this time. Thermal persist will be
particularly important in high performance thermoelectric systems
utilizing hot side thermal ballast 92 since net amount of heat
stored in heat sink 4 and hot side thermal ballast 92 is
substantial, to the extent that it increase the temperature of and
possibly damage the load being cooled should this heat be allowed
to flow in a reverse direction.
[0102] The high performance thermoelectric systems with thermal
ballast of the present invention allow for many applications, and
may be implemented in various applications to cool fluids, gasses,
and many other types of thermal loads. Although reference is made
to the embodiments listed above, it should be understood that these
are only by way of example and to identify the preferred use of the
device known to the inventors at this time. It is believed that the
high performance thermoelectric systems of the present invention
have many additional uses and implementations which will become
obvious once one is familiar with the fundamental principles of the
invention.
* * * * *