Note: Descriptions are shown in the official language in which they were submitted.
CA 02530560 2005-11-14
GEOTHERMAL COOLING DEVICE
TECHNICAL FIELD
The present invention relates generally to geothermal cooling systems,
and more particularly to a geothermal cooling device coupled with a
superconducting
heat transfer element for use as an air conditioner.
BACKGROUND OF THE INVENTION
Limitations of current art
Ground source heat pump systems, also known as geothermal or
geoexchange systems, have been used for cooling and heating homes for more
than
half a century. In 1993, the Environmental Protection Agency evaluated all
commercially available technologies and concluded that ground source heat
pumps
were the most energy efficient systems available to the consumer.
Conventional ground source heat pump systems operate on a simple
principle. In the cooling mode, heat from the building is collected at a heat
exchanger
and transferred to the heat pump, which concentrates the heat and transfers it
to a
ground source loop, which transfers the heat to the ground. In the heating
mode, heat
energy is absorbed from the ground and transferred to a heat pump which
concentrates
the heat and transfers it to the building's heat distribution system which in
turn heats the
building. In both modes, only a small amount of the heat energy comes from the
electricity that runs the compressor; most of the energy comes from the air
(in the
cooling mode) and the ground (in the heating mode). This allows ground source
heat
pump systems to achieve more than 100% efficiency: every unit of energy
consumed by
the heat pump produces more than a unit of useful energy in the form of heat.
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Even though ground source heat pump systems achieve efficiencies of up
to 350% compared to less than 100% for most conventional systems, they have
achieved a very low level of adoption in the commercial marketplace because
their
capital costs and installation costs have always been much higher than
conventional
systems.
These high capital and installation costs have largely been due to
fundamental inefficiencies in the ground loop subsystem. In a typical
installation, the
ground loop consists of hundreds or thousands of feet of looped plastic piping
buried in
deep trenches or deep holes drilled into the ground. An antifreeze solution
such as
glycol is pumped through this loop to transfer heat energy to the ground (in
the cooling
mode) or to absorb heat energy from the ground (in the heating mode). Few
installations have sufficient available land for trenching so loops are most
commonly
installed in deep holes and this makes them relatively expensive for several
reasons.
First, each loop consists of a supply and return line, which must fit down
the same hole. With an outer diameter of an inch or more for each pipe and a
tendency
for these pipes to bow away from each other due to the plastic material's
memory of
being coiled for shipment, the hole typically needs to have a diameter of 4 to
6 inches to
allow the loop to be installed. Holes of this size are relatively expensive to
drill and
require heavy equipment that disrupts landscaping, making it expensive to
retrofit
existing homes. Holes of this size also leave large voids around the loop that
must be
filled with materials such as bentonite clay in order for heat to transfer
from the ground
to the loop, which adds significantly to the cost of installation.
Second, having both supply and return lines in the same hole results in
thermal "short circuiting" which reduces the efficiency of the loop. In the
cooling mode,
for example, heat absorbed by the building's cooling system is transferred to
the fluid in
the ground loop system and pumped down a supply line into a bore hole. As it
goes
down the hole it loses heat to the cool ground, causing the ground to warm up -
more at
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the top of the hole because the fluid in the pipe is hottest as it enters the
top of the hole.
As the fluid goes down the tube it cools. When the cooled fluid comes back up
the hole
in the return line, it passes through the ground that was just heated, so the
fluid in the
pipe reabsorbs some of the heat it lost on the way down. This lowers the
efficiency of
the loop so the loop must be made longer to compensate, adding to the cost of
drilling
and piping.
Third, for the ground loop to function, the antifreeze solution must be
pumped through hundreds or thousands of feet of small diameter piping. This
consumes
a significant amount of electric energy, lowering the overall efficiency of
the system.
In recent years, a new ground source heat pump technology has evolved
to overcome some of the inefficiencies of conventional systems. This
technology,
called "direct geoexchange," replaces the conventional plastic ground loop
with a small-
diameter copper loop. Instead of an antifreeze solution, direct geoexchange
systems
pump a refrigerant through the loop to pick up heat from the ground or give
off heat to
the ground in the same way that conventional ground loops function.
Direct geoexchange has some significant advantages over conventional
systems. First, the direct geoexchange loop runs directly to and from the heat
pump's
compressor, eliminating the heat exchanger that is required by conventional
systems to
transfer heat from the loop to the heat pump. Second, the small diameter of
the direct
exchange loop makes it possible for loops to be installed in smaller diameter
holes in
the ground; this reduces the cost of drilling and backfilling the holes and
reduces the
size of the drill rig required to drill the holes, decreasing damage to
landscaping in
retrofit applications. Third, the copper pipes used in direct geoexchange
transfer heat
more efficiently to and from the ground so the total length of loop required
is typically
less than conventional systems. Because of these improvements, direct
geoexchange
systems can be cheaper to install than conventional ground source systems and
more
energy efficient.
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In spite of these inherent advantages, direct geoexchange also has some
significant disadvantages. First, both supply and return pipes run in the same
hole, so
the thermal short circuit problems of conventional systems remain. Second, the
loop
system pumps much more refrigerant through many more feet of piping past many
more
connections than conventional systems, so the potential for refrigerant leaks
is
increased.
Both direct geoexchange and conventional ground source heat pump
systems have additional limitations that affect their usefulness. First, they
are designed
to heat and cool whole buildings, so neither can efficiently be installed on
the
incremental room-by-room basis on which most of the world - particularly the
developing world - installs air conditioning. Second, they require significant
amounts of
electrical energy to operate pumps and compressors; this power is not often
available or
reliable in many parts of the world.
Most of the world either does without air conditioning (where money and
electricity are in short supply), or uses refrigerant-based room air
conditioners to cool
individual rooms. Like geothermal systems (in the cooling mode), room air
conditioners
use a refrigeration circuit to absorb heat from room air and intensify it so
it can be
dissipated outside the building. Unlike geothermal systems, room air
conditioners
dissipate this heat into the outside air instead of the ground. Because air
conditioning is
usually used when the outside air is hot - often more than 40 degrees
Farenheit hotter
than the ground in a geothermal installation -- the process of dissipating
heat to the air
requires air conditioners to work much harder and use much more energy than
geothermal heat pumps to produce the same amount of cooling.
In spite of their high electrical power consumption, room air conditioners
have dominated world markets because they are inexpensive to buy and simple to
install. Rising demand for energy, however, is changing these markets. Rising
demand
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is causing the cost of electricity to rise, making inefficient systems such as
room air
conditioners much less attractive to consumers. Rising demand is also causing
shortages of power. Metropolitan areas such as Shanghai are finding that room
air
conditioners are consuming as much as two thirds of the capacity of the entire
electrical
grid on hot summer days, destabilizing the grid and leaving too little power
for the
manufacturing sector to operate during the day.
There is a need for a cooling device that consumes significantly less
power than conventional air conditioners and is cheaper to buy, easier to
install and has
fewer moving parts than ground source heat pump systems.
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SUMMARY OF THE INVENTION
Cooling devices are provided that use a thermal superconducting transfer
medium to absorb heat from a room and transfer that heat to the ground where
it can be
dissipated. The thermal superconducting transfer medium in these devices
allows heat
to move between building and ground without the assistance of a compressor or
refrigeration circuit, and without the assistance of a ground loop and
associated pumps,
valves and circulating fluids. This reduces the power required to operate
these cooling
systems, and also eliminates refrigerant leaks and reduces cost and system
complexity.
According to one aspect of the present invention, there is provided a
cooling device suitable for coupling to a thermal superconductor geothermal
ground coil
extending below a ground level allowing passive thermal conduction to an earth
source.
The cooling device includes a thermal superconductor having a first end
couplable to
said thermal superconductor geothermal ground coil and a second opposing end
configured as a thermal superconductor exchange segment, and a blower
positioned in
the region of said thermal superconducting exchange segment, and a thermostat
controller associated with an indoor space, programmable to a desired
temperature set
point and for measuring temperature of said indoor space and further having
control
means connected to said blower. The control means operate the blower in
response to
the difference between the set point and the measured temperature, for the
purpose of
operating in a cooling mode to efficiently cool an indoor space.
According to another aspect of the present invention, there is provided a
cooling device operable without a thermostat and suitable for coupling to a
thermal
superconductor geothermal ground coil extending below a ground level allowing
passive
thermal conduction to an earth source. The cooling device includes a thermal
superconductor having a first end couplable to said thermal superconductor
geothermal
ground coil and a second opposing end configured as a thermal superconductor
exchange segment, and a blower positioned in the region of said thermal
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superconducting exchange segment, and a power connection for providing
operating
power to said blower when connected, and a switch connected to the power
connection
and the blower for controlling the blower. The blower may be manually
controlled for the
purpose of operating in a cooling mode to efficiently cool an indoor space.
According to another aspect of the present invention, there is provided a
simple cooling device without thermostat or switch that is suitable for
coupling to a
thermal superconductor geothermal ground coil extending below a ground level
allowing
passive thermal conduction to an earth source and for connecting to a power
source.
The cooling device includes a thermal superconductor having a first end
couplable to
said thermal superconductor geothermal ground coil and a second opposing end
configured as a thermal superconductor exchange segment, and a blower
positioned in
the region of said thermal superconducting exchange segment, and a power
connection for providing operating power to said blower when connected. The
blower
may be powered by connecting the external power connector to the power source,
for
the purpose of operating in a cooling mode to efficiently cool an indoor
space.
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BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1: A GEOTHERMAL COOLING DEVICE: This figure shows a
schematic of an efficient geothermal cooling device couplable to a ground
source.
Figure 1a shows an alternate embodiment with multiple ground source loops.
FIGURE 2: COOLING DEVICE POWERED BY ALTERNATIVE ENERGY
SOURCE: This figure shows a schematic of an embodiment of an efficient
geothermal
cooling device powered by an alternative energy source and having a power
conditioner.
FIGURE 3A,B: GEOTHERMAL COOLING SYSTEM INTEGRATED INTO
AN INTERIOR SPACE: This figure shows a a) perspective and b) sectional view of
an
embodiment of an efficient geothermal cooling device formed of a thermal
superconductor extending to the ground source.
FIGURE 4: A GEOTHERMAL COOLING SYSTEM WITH A PLURALITY
OF AIR EXCHANGE SEGMENTS: This figure shows a schematic of multiplexed cooling
segments couplable to a single ground loop and connected to a power and sensor
control box.
FIGURE 5: A GEOTHERMAL COOLING DEVICE WITH BLOWER
POWER SWITCH: This figure shows a schematic of a geothermal cooling device
with a
power switch for operating the blower for additional air heat transfer.
FIGURE 6: A GEOTHERMAL COOLING DEVICE: This figure shows a
schematic of a geothermal cooling device with a power connector for manually
powering
the blower for additional air heat transfer.
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DETAILED DESCRIPTION OF THE INVENTION
With reference to the drawings, new and improved cooling devices and
systems for improved cooling embodying the principles and concepts of the
present
invention will be described. In particular, the devices and systems are
operable in the
conditions where an earth source temperature is lower than an above ground
temperature associated with an interior space to be cooled. The earth source
may
alternatively be a ground source or a body of water effectively below ground
level.
Recent advances in thermal superconducting materials can now be
considered for use in novel energy transfer applications. For example, US
patent
6132823 and continuations thereof, discloses an example of a heat transfer
medium
with extremely high thermal conductivity, and is included herein by reference.
Specifically the following disclosure indicates the orders of magnitude
improvement in
thermal conduction; "Experimentation has shown that a steel conduit 4 with
medium 6
properly disposed therein has a thermal conductivity that is generally 20,000
times
higher than the thermal conductivity of silver, and can reach under laboratory
conditions
a thermal conductivity that is 30,000 times higher that the thermal
conductivity of silver."
Such a medium is thermally superconducting. Throughout the disclosure, the
term
superconductor shall interchangeably mean thermal superconductor or thermal
superconductor heat pipe. The available product sold by Qu Energy
International
Corporation is an inorganic heat transfer medium provided in a vacuum sealed
heat
conducting tube.
Alternate thermal superconductors may be equivalently substituted, such
as thermally superconducting heat pipes. Heat pipes typically include a sealed
container(pipe),working fluid and a wicking or capillary structure inside the
container.
Heat is transported by an evaporation-condensation cycle when a thermal
differential is
present between opposing ends. Working fluids can be selected with high
surface
tension to generate a high capillary driving force such that the condensate
can migrate
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CA 02530560 2005-11-14
back to the evaporator portion, even against gravity. Some working fluids
useful for the
geothermal operating temperature range include ammonia, acetone, methanol and
ethanol. Inside the tube, the liquid enters and wets the internal surfaces of
the capillary
structure. Applying heat at one segment of the pipe, causes the liquid at that
point to
vaporize picking up latent heat of vaporization. The gas moves to a colder
location
where it condenses, giving up latent heat of vaporization. The heat transfer
capacity of a
heat pipe is proportional to the axial power rating, the energy moving axially
along the
pipe. For maximum energy transfer the heat pipe diameter must be increased and
the
length shortened, making it operable but less preferred than a non-liquid
superconductor such as the Qu product. In particular with respect to the
ground loop,
scaled up heat pipe designs have been disclosed for geothermal heating
applications
such as for PCT publication WO 86/00124, "Improvements in earth heat recovery
systems", these designs partially overcome the length to diameter ratio
problem but
preferably require a recirculation pump for the fluid. A two way heat pipe
design for
ventilation heat-exchanger is disclosed in US patent 4896716, and could be
used for
non-ground loop transfer as a two way thermal superconductor.
When suitably configured for geothermal cooling, thermal superconductors
of this kind result in many significant advantages. In particular, because
they transfer
heat at a very high rate, they are able to absorb heat in a building, transfer
it quickly and
efficiently out of the building over relatively long distances of hundreds of
feet with little
loss of energy, and then dissipate this energy into the cool ground, without
the
mechanical pumping of circulating fluids required to move heat in conventional
geothermal systems.
Figure 1 illustrates an embodiment of the invention. Geothermal cooling
device 110 is positioned above ground level 30 and couplable to a geothermal
heat
exchange element 32 formed from thermal superconductor and positioned in a
ground
loop hole 34. The thermal superconductor extends above ground level where it
is
covered by insulation 25 and terminated in a coupler 28. For illustrative
purposes, this
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superconductor may be in the form of a sealed metal tube as currently
available from
Qu Corporation and will be considered to be in tube form. Alternatively other
available
thermal superconductors could be similarly substituted that may have various
forms and
cross sections such as flexible conduits, thin laminate, thinfilm coated metal
etc.
Optionally, the superconducting transfer segments maybe formed from
discontinuous
discrete sections of superconducting material separated by small gaps of a non-
superconducting material.
In the preferred case, the depth of hole 34 is selected in combination with
the transfer properties of geothermal heat exchange element 32, the heat
absorbing
properties of the ground at the hole and the quantity of heat required by the
system to
be dissipated into the ground. As per conventional geoexchange systems, the
depth of
hole 34 may be greater than is practicable for a single hole, so a plurality
of holes may
be substituted to receive a plurality of geothermal heat exchange elements
with an
aggregate depth equal to or greater than the required depth of a single hole.
As shown
in Figure 1 a, this plurality of geothermal heat exchange units can be joined
at or below
coupler 28 in such a manner that they are equally able to transfer heat to the
ground.
Due to the superior thermal transfer properties of the thermal superconductor
element
and the fact that the element is not looped so thermal "shortcircuiting" is
avoided, the
hole size and depth can be considerably less than conventional geoexchange
loops,
saving installation costs and enabling installation in places where the large
holes
required by conventional geoexchange are not practical. In the example of a
body of
water being the earth source, the superconducting ground coil can be either
suspended
in the body of water, or in indirect thermal contact with the body of water.
The latter
example is specifically useful for marine applications.
The coupler 28 couples between the ground loop superconductor 32 and
a cooling device superconductor segment 26, providing for ease of installation
and
conduit routing into an interior location prior to connection. The cooling
device
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superconductor segment 26 extends inside a housing 10. As obvious to one
skilled in
the art, the coupler 28 could equivalently be alternatively positioned under
the ground,
above ground outside a building, inside the building but outside the housing
10, or even
inside the housing 10, as selected for best ease of installation. Housing 10
includes two
vented regions (not shown), an inlet region to draw hot air in, and an outlet
region to
push cool air out. Positioned within housing 10 and between the two vented
regions is a
thermally superconducting air exchanger 20 connected to or integral with the
cooling
device superconductor segment 26, which is further insulated by insulation 25
up to the
air exchanger 20. A blower 18 is positioned in proximity to the
superconducting air
exchanger to pull or push air through the exchanger for cooling, the preferred
position
being near the outlet vent region such that air is pulled over the air
exchanger 20. Due
to the superior heat transfer properties of the exchanger, the fan can be a
low power,
low throughput fan to conserve energy, or alternatively a variable speed fan.
The
preferred fan has operating noise less than 45 dB and can be DC powered by an
alternative energy source (not shown). Superconducting air exchanger 20 may be
configured in many possible designs provided sufficient net surface area is
exposed to
the air flow through cooling device 110, the illustrated design of an array of
bars
substantially corresponding to the fan diameter is a preferred example. Blower
18 is
connected to controller 14 and power line 12 for control of fan operation. In
some
atmospheric conditions, condensate will form on the superconductor heat
exchanger 20,
and an optional drip tray 22 is shown positioned below to catch condensate and
an
optional water drain line 24 is shown connected to drip tray for runoff
disposal.
The controlled operation of the geothermal cooling device 110 is essential
for user comfort and control of cooling. Controller 14 may be programmed as a
thermostat controller responding to a temperature sensor 16 (such as a
thermocouple)
associated with the space to be cooled, or as a cooling device controller that
receives
input from a remote thermostat and sensor associated with the space (not
shown). The
controller is shown within the housing 10, but may alternatively be in any
location
provided it is in communication with the blower and temperature sensor. While
the
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simplest implementation is one temperature measurement, to one skilled in the
art,
multiple temperature measurements could be weighted or averaged for the
purpose of
feedback set points in the controller 14. In the case of a multi-speed fan,
alternatively a
second temperature sensor could be positioned on or near the air exchanger 20
to
determine the initial fan speed for faster cooling. Unlike conventional
central geothermal
heat pumps, which are large, noisy and require greater power than available
from a
standard household outlet, the geothermal cooling device 110 can be operated
from a
standard outlet, anywhere in the house, very quietly and in a small form
factor housing.
The housing 10 for geothermal cooling device 110, may be positioned anywhere
within
the interior room to be cooled; it does not have to be near or in a window
region.
Preferably the housing is positioned to provide optimum air mixing and cooling
for the
room.
With the controller 14 set to a desired room temperature T1 via a manual
input (not shown), or a remote control input or a second remote thermostat
(not shown)
in communication with the controller 14, the controller senses existing room
temperature
T2 and if higher than T1, operates the blower 18 to circulate air until the
temperature
reaches T1. Alternatively, as common in the art, various thresholding or
smoothing
processes can be programmed to avoid jitter and to determine when to switch
the
blower 18 on or off. In the example of a multi-speed blower, the blower speed
can be
programmed to change proportional to the rate of change of existing
temperature T2, in
addition to on or off. The geothermal cooling device 110 can be programmed to
operate
for any input that acts as a related proxy for associated interior temperature
and has a
known characterized relationship to temperature.
The geothermal cooling device 110 of figure 1 has many advantages that
solve the problems described in the background, due to the substantial
efficiency
increase relative to existing cooling solutions. First, the geothermal earth
source
element is not looped so it is not subject to thermal shortcircuiting, so hole
depth can be
less than conventional ground loop depth, reducing costs and increasing
qualifying
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sites. Second, by eliminating a compressor and heat intensifying circuit or
circulating
pumps, the power requirements of the geothermal cooling device are an order of
magnitude less than conventional geothermal exchange units, whether central or
for a
single room, and permit the installation and operation on low power electrical
systems
such as conventional 15 Ampere residential circuits. Third, the generated
noise is
orders of magnitude better than compressor driven geothermal exchange units.
Fourth,
the lightweight and small size of the geothermal cooling device 110 relative
to existing
solutions, permits easy installation in a wide range of locations and even
installations of
individual geothermal cooling devices 110 in multiple rooms of a residence
interior.
Fifth, eliminating refrigerant and reducing moving parts extends system
lifetimes and
reduces system maintenance.
The geothermal cooling device may operate from an alternative energy
power source for even more economical sustainable operation, as shown in
Figure 2.
This embodiment is similar to Figure 1 with the addition of a power converter
11 inside
the enclosure and connected to power line 12, for the purpose of processing
alternative
energy from power source 9. Power source 9 may be a hydrogen fuel cell, a
solar cell
array, or a wind turbine and the like, resulting in DC power requiring
conditioning by
power converter 11 to supply controller and fan power. Due to the efficient
thermal
transfer of the configuration, low voltage components (12V) can be used in an
embodiment, permitting alternate energy sources to be used without
conditioning.
Preferably the alternative power source would supply continuous power, but
controller
14 may be adapted to use intermittent power operation.
Alternatively, for reducing potential thermal losses through coupler 28
shown in Fig's 1 and 2, a geothermal cooling system can be designed where the
thermal superconductor is formed as one integral loop from earth source
segment 32
through to superconductor air exchanger 20, by eliminating coupler 28. In this
example,
installation is done differently. The housing 10 is installed in position in
the interior
space, and both the above ground insulated thermal superconductor segment 26
and
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uninsulated segment 32 are routed through openings from the interior to the
ground 30,
and uninsulated segment 32 is seated in the ground loop hole. The interior
openings
may be either through a sidewall and out to an uncovered hole, or in the case
of new
building may be positioned in the foundation of the building and fed into
ground loop
holes underneath the building.
Due to the advantages of lightness and compactness, interior mounting
can be considered for geothermal cooling devices that was previously not
feasible. In
Figure 3 and 3a, an example is shown for a wall-integrated geothermal cooling
device
130 mounted on interior wall 52, in perspective view to show air circulation
and in
sectional view to show installation assembly. In Figure 3a, necessary
connections are
shown as coming up from below the interior wall 52 for illustration. Thermal
superconductor earth source loop 32 extends into the ground 30 and terminates
in
coupler 28 above ground. The three connections to the cooling device 130
include a
water drain line 24, a cooling device thermal superconductor segment 26
couplable to
coupler 28, and power line 36 couplable to power supply/mains (not shown); the
three
are shown supported in conduit 38 that serves for protection when exteriorly
mounted,
and fastening through wall opening 55. The conduit 38 is terminated at housing
10 and
delivers the 3 services to the internal components. It will be obvious to one
skilled in
construction that the conduit could be routed or positioned at any point on
the wall or
routed partially on the interior side of the wall, or interior to the wall
within the scope of
the embodiments, or alternatively, that the services contained in the conduit
could be
separately routed within or outside the structure. It will also be obvious
from the
disclosure of this invention that water drain line 24 could be eliminated in
installations
where environmental conditions do not result in condensation sufficient to
require
collection and drainage. Housing 10 is secured to the wall, either by conduit
38 or by
separate fasteners such as wall-anchors not shown, in a manner that meets
building
codes.
Housing 10 has inlet vents 53 underneath and outlet vents 54 at the room
facing side, such that cooled air is circulated as shown by the arrows in Fig
3a. The fan
CA 02530560 2005-11-14
18 and thermal superconductor air exchanger 20 are positioned preferably at
the outlet
vent 54 and operated to pull the air from the inlet. Any arrangement of inlet
and outlet
can be configured on the exposed sides of the housing, but the preferred
arrangement
is shown. Additionally the controller 14 (not shown) and thermostat (not
shown) can be
enclosed in housing 10 and connected to power line 36 for operation, and as
discussed
previously various user controls may be provided on the housing exterior or by
way of a
remote control. Alternate versions may have the coupler 28 moved inside the
housing
10, or along the conduit path between the ground 30 and housing 10.
Alternatively, for
ease of installation the conduit may have a conduit coupler (not shown) such
that the
geothermal cooling device 130 can be installed in stages. The integrated
cooling device
provides safety in that all wires and supply lines are less accessible and
reduces
installation costs as normal power wiring can be used, and the housing can be
safely
and quickly wall-mounted with common mechanical fasteners, without requiring
reinforced supports or cutaways in the wall.
Figure 4 demonstrates a multiplexed version of the geothermal cooling
device 140. A similar thermal superconductor ground loop 32 is coupled to two
or more
superconductor air exchangers 20 and 20a though two or more cooling device
superconductor segments 26 and 26a with insulation 25 (as shown generally on
above-
grade superconductor transfer segments). Housings 42 and 42a respectively
enclose
the air exchangers 20, 20a, associated blowers 18, 18a and optional drip trays
22, 22a
and optional drain lines 24,24a, and have inlet and outlet vents (not shown in
schematic
view). The controller 14, temperature sensor 16 and power line 12, can be
housed in
one of the housings 42, 42a, and connects to both blowers 18, 18a through
power lines
37, 37a. The configuration as described allows for distributed cooling through
a single
thermostat, for example in a large interior space where one cooling device is
inadequate. The operation would be as described previously. Alternate
embodiments
could have separate thermostat in each enclosure with separate set points for
controlling each blower individually, or separate thermostat controller and
sensor for
each blower integrated into housings 42 and 42a.
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In all the examples of geothermal cooling devices thus far, a thermostat
has been used to control operation. The superconducting air exchanger can be
effectively "cool" with no power and doesn't have to be "disconnected" from
the ground
loop. Therefore, for further parts reduction it may be desired to remove the
thermostat
and provide manual controls only, as shown in Figures 5, 6. In Figure 5, a
geothermal
cooling device 150 consists of enclosure 10, cooling device superconductor
segment 26
with insulation 25, superconductor air exchanger 20, blower 18, power line 12
to exterior
power supply (not shown) and user operable switch 40 in series with power line
12 to
switch fan off or on. When cooling device superconductor segment is coupled to
thermal
superconductor ground loop at coupler 28, heat is transferred from air
exchanger 20 to
earth 30 through the thermal superconductor, at a rate determined by blower
operation
and temperature differential. It will be appreciated in an alternate
arrangement that
blower 18 could be a multi-speed blower and switch 40 could be a variable
control
switch such that the user could control various speed settings.
Figure 6 varies from Figure 5 in that the switch has been removed. Power
line 12 is terminated in an electrical connection such as a plug, so that user
operates
the geothermal cooling device 160 by plugging or unplugging power to the
blower of the
geothermal cooling device 160.
17
