U.S. patent application number 11/619493 was filed with the patent office on 2007-09-13 for thermal superconductor refrigeration system.
Invention is credited to John Graham, Lynn Mueller.
Application Number | 20070209380 11/619493 |
Document ID | / |
Family ID | 38227867 |
Filed Date | 2007-09-13 |
United States Patent
Application |
20070209380 |
Kind Code |
A1 |
Mueller; Lynn ; et
al. |
September 13, 2007 |
THERMAL SUPERCONDUCTOR REFRIGERATION SYSTEM
Abstract
A superconductor refrigeration system incorporates thermal
superconducting heat transfer. The system includes an intensifying
heat exchanger, a refrigerating heat exchange coil formed from
thermal superconductor material, and a dissipating heat exchange
coil formed from thermal superconductor material. The system can
also include a switch connected to condenser and evaporator heat
exchange segments, a refrigeration switch segment and a dissipating
switch segment such that in a first switch position a refrigerating
mode is provided and in a second switch position a defrost mode is
provided. Additional embodiments include thermostat controllers and
blowers for enhanced control. Heat exchange and reuse is described
for multiple heat exchangers coupled by thermal superconductors. A
defrosting element is described for refrigeration heat
exchangers.
Inventors: |
Mueller; Lynn; (Richmond,
CA) ; Graham; John; (Vancouver, CA) |
Correspondence
Address: |
MCANDREWS HELD & MALLOY, LTD
500 WEST MADISON STREET
SUITE 3400
CHICAGO
IL
60661
US
|
Family ID: |
38227867 |
Appl. No.: |
11/619493 |
Filed: |
January 3, 2007 |
Current U.S.
Class: |
62/260 ;
62/324.1 |
Current CPC
Class: |
F25B 2700/11 20130101;
F28F 2013/008 20130101; F25B 47/025 20130101; F28F 13/00 20130101;
F28F 2013/001 20130101; F25B 25/005 20130101; F25D 21/06
20130101 |
Class at
Publication: |
062/260 ;
062/324.1 |
International
Class: |
F25D 23/12 20060101
F25D023/12; F25B 13/00 20060101 F25B013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 3, 2006 |
CA |
2,530,621 |
Claims
1. A superconductor refrigeration system having thermal
superconducting heat transfer, the system comprising: (a) a
reversible intensifying heat exchanger, having i. a compressor; ii.
a first heat exchanger and a second heat exchanger, each of said
heat exchangers adapted to function interchangeably as an
evaporator and a condenser, wherein said first heat exchanger is
operable as an evaporator and said second heat exchanger is
operable as a condenser when said system is operating in cooling
mode, and wherein said first heat exchanger is operable as a
condenser and said second heat exchanger is operable as an
evaporator when said system is operating in heating mode; iii. at
least one first conduit in communication with said compressor and
each of said heat exchangers and adapted for carrying refrigerant
through said system to each of said heat exchangers, said at least
one conduit including a return conduit for carrying refrigerant gas
back to said compressor; iv. a reversing valve in communication
with said at least one conduit and configured to reverse the flow
of refrigerant from said compressor to said heat exchangers
depending upon whether said system is operating in said cooling
mode or said heating mode; whereby when said intensifier heat
exchanger is operating in heating mode, said valve is activated to
direct refrigerant pumped from said compressor through said at
least one conduit to said first heat exchanger where said
refrigerant gas is condensed into liquid, through said return
conduit to said second heat exchanger where said liquid is
vaporized into gas and heat is transferred from earth source
through said thermal superconductor, and back to said compressor
via said return conduit; and whereby when said intensifier heat
exchanger is operating in cooling mode, said valve is activated to
direct refrigerant pumped from said compressor through said at
least one conduit to said second heat exchanger where said
refrigerant gas is condensed into liquid and heat is transferred to
earth source through said thermal superconductor, through said
return conduit to said first heat exchanger wherein said liquid is
vaporized into gas, and back to said compressor via said return
conduit; (b) a refrigerating heat exchange coil formed from thermal
superconductor material, having a transfer segment terminating at
opposing ends at a refrigerating heat exchange segment and a
refrigerating heat exchange segment coupled to one of said first or
second heat exchangers; and (c) a dissipating heat exchange coil
formed from thermal superconductor material, having a transfer
segment terminating at opposing ends at a dissipating heat exchange
segment and a dissipating heat exchange segment coupled to the
other one of said first or second heat exchangers, wherein said
reversing valve can be configured to provide corresponding
refrigerating or defrosting modes of said superconductor
refrigeration system.
2. The superconductor refrigeration system of claim 1, further
comprising a thermostat controller associated with a location
proximal to said refrigerating heat exchange segment, programmed
with a desired temperature set point and for measuring temperature
of said space and further connected to said reversing valve and
said compressor, wherein both said compressor is operated and said
reversing valve position controlled in response to one of the
difference between said temperature set-point and said measured
temperature and a preset timer.
3. The superconductor refrigeration system of claim 2, further
comprising a blower positioned to circulate air over said
refrigerating heat exchange segment, and connected to said
controller, wherein said blower is operated in response to one of
the difference between said temperature setpoint and said measured
temperature and a preset timing.
4. The superconductor refrigerating system of claim 3, further
comprising a second blower positioned to circulate air over said
dissipating heat exchange segment, and wherein said thermostat
controller is connected to said blower to operate said blower in
response to difference between said measured temperature and said
setpoint for the purpose of dissipating heat.
5. The superconductor refrigerating system of claim 1, wherein said
thermal superconductor material is an inorganic high heat transfer
medium
6. The superconductor refrigerating system of claim 5, wherein said
high heat transfer medium is applied in a sealed heat transfer
pipe.
7. The superconductor refrigerating system of claim 6, wherein said
thermal superconductors are heat transfer pipes containing said
high heat transfer medium, and insulated along at least a portion
of heat transfer segment, said heat transfer pipes having thermal
conductivity greater than 100 times the thermal conductivity of
silver and approximately negligible heat loss along said heat
transfer segment.
8. The superconductor refrigerating system of claim 4, wherein said
refrigerating and dissipating heat exchange segments are arranged
as condenser arrays having area approximately corresponding to said
blower area for increased air heat exchange.
9. The superconductor refrigerating system of claim 1, wherein at
least a portion of said thermal superconductors are formed in
discrete segments joined by approximately short thermally
conducting joiners.
10. The superconductor refrigerating system of claim 2, further
comprising a plurality of refrigerating heat exchange segments
coupled to a to said condenser heat exchange segments.
11. The superconductor refrigerating system of claim 10, further
comprising a plurality of blowers positioned proximal to each of
said refrigerating heat exchange segments and said dissipating heat
exchange segments and connected to said thermostat controller.
12. The superconductor refrigerating system of claim 10, further
comprising a plurality of temperature sensors associated with said
plurality of heat exchange coils providing independent temperature
measurement, and said plurality of heat exchange switches are
switchable in response to respective differences between said
individual temperature measurements and corresponding associated
temperature set points.
13. The superconductor refrigerating system of claim 1, further
comprising an auxiliary fluid loop coupled to said dissipating
exchange segment and having a fluid pump, for the purpose of
exchanging heat from or to said superconductor refrigerating
system.
14. The superconductor refrigerating system of claim 13, wherein
said fluid is water.
15. The superconductor refrigerating system of claim 14, wherein
said auxiliary water loop is for the heating of water.
16. The superconductor refrigerating system of claim 14, wherein
said auxiliary water loop uses heat from waste water.
17. The superconductor refrigerating system of claim 13 wherein
said fluid is refrigerant and said fluid pump is a compressor.
18. The superconductor refrigerating system of claim 17 wherein
heat is exchanged between the refrigerant loop and the
superconductor heat exchange segments though direct thermal
contact.
19. The superconductor refrigerating system of claim 17 wherein
heat is exchanged between the refrigerant and the superconductor
heat exchange segment through an intermediating fluid.
20. The superconductor refrigerating system of claim 19 wherein
said intermediating fluid acts as a thermal storage mass.
21. The superconductor refrigerating system of claim 1, further
comprising a receiver connected to said thermostat controller and a
remote control in communications with said receiver such that
thermostat setpoints and operations can be controlled
wirelessly.
22. The superconductor refrigerating system of claim 1 further
comprising a programmable timer connected to said thermostat
controller such that defrost cycles can be activated at
time-controlled intervals.
23. The superconductor refrigerating system of claim 11, further
comprising thermostat controller to vary the operating speed of
said blowers separately, such that the cooling or heating
characteristics of said refrigerating and heat dissipating heat
exchangers can be individually controlled.
24. The superconductor refrigerating system of claim 1, further
comprising an ice buildup sensor located approximately at said
refrigerating heat exchange segment and connected to said
controller, wherein said switch position is selected for defrosting
mode upon said sensor reaching a programmed setpoint
25. The superconductor refrigerating system of claim 24, further
comprising an optical sensor to detect ice build up on heat
exchangers.
26. The superconductor refrigerating system of claim 24, further
comprising an air pressure sensor to detect ice build up on heat
exchangers.
27. The superconductor refrigerating system of claim 3, further
comprising: (a) a plant enclosure which houses said compressor,
said controller, said intensifying heat exchanger and said
reversing valve; and (b) a heat exchange enclosure which houses
said refrigerating heat exchange segment and blower and thermal
sensor, and having venting near said blower suitable for
circulation of air through an inlet and outlet, wherein said plant
enclosure and said heat exchange enclosures are at least connected
by one end of said refrigerating heat exchange segment and
communications control to said blower and said thermal sensor.
28. The superconductor refrigerating system of claim 27, wherein
said heat exchange enclosure is configured to be suspended in a
space to be refrigerated.
29. The superconductor refrigerating system of claim 11, further
comprising (a) a plant enclosure which houses said compressor, said
controller, said intensifying heat exchanger and said thermal
switches; and (b) a plurality of heat exchange enclosures, each of
which houses one of corresponding said refrigerating heat exchange
segment, blower and thermal sensor, said enclosure having venting
near said blower, wherein said plant enclosure and said plurality
of heat exchange enclosures are connected by at least said
corresponding refrigerating switch segments and communications
controls to said blowers.
30. A superconductor defrosting system having thermal
superconducting heat transfer, the system comprising: (a) an
intensifying heat exchanger, having i. a refrigerant coil which
receives refrigerant in the heating and cooling cycle; ii. a first
condenser heat exchange segment of said coil; iii. a first
evaporator heat exchange segment of said coil; iv. an evaporator to
expand liquid refrigerant to partial liquid and located between
said exchange segments; and v. a compressor for compressing and
circulating a refrigerant in said refrigerant coil; (b) a
defrosting heat exchange coil formed from thermal superconductor
material, having a transfer segment terminating at opposing ends at
a defrosting heat exchange segment and a second condenser heat
exchange segment; (c) an absorbing heat exchange coil formed from
thermal superconductor material, having a transfer segment
terminating at opposing ends at an absorbing heat exchange segment
and a second evaporator heat exchange segment; and (d) a controller
programmable to a desired set point and further having a thermostat
controller connected to said thermal switch and said
compressor.
31. The superconductor defrosting system of claim 30, further
comprising a blower positioned to circulate air over said
defrosting heat exchange segment, and connected to said
controller.
32. The superconductor refrigerating system of claim 31, further
comprising a second blower positioned to circulate air over said
absorbing heat exchange segment.
33. The superconductor defrosting system of claim 30, wherein said
thermal superconductor material is an inorganic high heat transfer
medium.
34. The superconductor defrosting system of claim 33, wherein said
high heat transfer medium is applied in a sealed heat transfer
pipe.
35. The superconductor defrosting system of claim 34, wherein said
thermal superconductors are heat transfer pipes containing said
high heat transfer medium, and insulated along at least a portion
of heat transfer segment, said heat transfer pipes having thermal
conductivity greater than 100 times the thermal conductivity of
silver and approximately negligible heat loss along said heat
transfer segment.
36. The superconductor defrosting system of claim 32, wherein said
defrosting and absorbing segments are arranged as condenser arrays
having area approximately corresponding to the areas of said
blowers for increased air heat exchange.
37. The superconductor defrosting system of claim 30, wherein at
least a portion of said thermal superconductors are formed in
discrete segments joined by approximately short thermally
conducting joiners.
38. The superconductor defrosting system of claim 30, wherein said
defrosting heat exchange segment is arranged as a thermal conductor
bus extending to a plurality of said defrosting heat exchange
coils, and said absorbing heat exchanger segment is arranged as a
thermal conductor bus extending to a plurality of said absorbing
heat exchanger coils, to provide a corresponding heat transfer
capacity.
39. The superconductor defrosting system of claim 38, further
comprising a plurality of blowers positioned proximal to each of
said defrosting heat exchange segments and said absorbing heat
exchange segments and couplable to said thermostat controller.
40. The superconductor defrosting system of claim 30, further
comprising a receiver connected to said thermostat controller and a
remote control in communications with said receiver such that
controller setpoints and operations can be controlled
wirelessly.
41. The superconductor defrosting system of claim 30, further
comprising a programmable timer connected to said controller such
that defrost cycles can be activated at time-controlled
intervals.
42. The superconductor defrosting system of claim 39, further
comprising a thermostat controller to vary the operating speed of
said blowers separately, such that the cooling or heating
characteristics of said defrosting and heat absorbing heat
exchangers can be individually controlled.
43. The superconductor defrosting system of claim 30, further
comprising an ice buildup sensor located approximately at said
defrosting heat exchange segment and connected to said controller,
wherein said switch position is selected for defrosting mode upon
said sensor reaching a programmed setpoint
44. The superconductor refrigerating system of claim 43, further
comprising an optical sensor to detect ice build up on said
refrigerating heat exchange coils.
45. The superconductor refrigerating system of claim 43, further
comprising an air pressure sensor to detect ice build up on heat
exchanger coils.
46. The superconductor refrigerating system of claim 32, further
comprising: (a) a plant enclosure which houses said compressor,
said controller, said intensifying heat exchanger and said thermal
switch; and (b) a defrosting heat exchange enclosure which houses
said defrosting heat exchange segment and and thermal sensor and
said blower (c) a absorbing heat exchange enclosure which houses
said heat absorbing heat exchange segment and and thermal sensor
and said blower wherein said plant enclosure is connected to said
defrosting heat exchanger enclosure and said heat absorbing heat
exchange enclosure by at least said condenser heat exchange segment
and said evaporator heat exchange segment and communications
control to said blowers.
47. The superconductor refrigerating system of claim 44, wherein
said heat exchange enclosure is configured to be suspended in a
space to be refrigerated.
48. The superconductor refrigerating system of claim 39, further
comprising (a) a plant enclosure which houses said compressor, said
controller, said intensifying heat exchanger; and (b) a plurality
of heat exchange enclosures, each of which houses one of
corresponding said defrosting heat exchange segment and said
blower, said enclosure having venting near said blower, wherein
said plant enclosure and said plurality of heat exchange enclosures
are connected by at least said corresponding condenser heat
exchange segments and communications controls to said blowers.
49. A superconductor refrigeration exchange element for use in an
air flow path, comprising: (a) a plurality of evaporator
refrigerant conduits suitable for receiving refrigerant; (b) an
evaporator coupled to ends of each of said plurality of refrigerant
coils; (c) a condenser conduit coupled to opposing ends of each of
said plurality of refrigerant coils; (d) a plurality of cooling
plates formed of a thermally conductive material arranged in a
approximately co-planar stack, and having at least one conduit
opening through each of said plates corresponding to each
refrigerant conduits such that said conduits are seated in thermal
contact within said cooling plate stack for the purpose of
exchanging heat with air; (e) a thermal superconductor heat
transfer pipe arranged such that a coupling portion is coupled on
at least one side of said cooling plates stacks such that thermal
contact is created between said cooling plates and said heat
transfer pipe, the location of said coupling portion relative to
said seated conduits is arranged to increase available air flow
through said plates, and a transfer portion extends away from said
stack of plates; and (f) insulation surrounding at least part of
said extended portion to reduce heat transfer loss; wherein heat is
transferred from said cooling plates by said refrigerant conduits
for the purposes of cooling said air flow and heat is transferred
to cooling plates by said thermal superconductor heat transfer pipe
for defrosting ice build up on said cooling plates such that said
air flow is approximately maintained.
50. The superconductor defrosting element of claim 49, further
comprising a blower positioned to circulate air over said
defrosting heat exchange segment.
51. The superconductor defrosting element of claim 49, wherein said
thermal superconductor material is an inorganic high heat transfer
medium.
52. The superconductor defrosting element of claim 49, wherein said
high heat transfer medium is applied in a sealed heat transfer
pipe.
53. The superconductor defrosting element of claim 52, wherein said
thermal superconductors are heat transfer pipes containing said
high heat transfer medium, and insulated along at least a portion
of heat transfer segment, said heat transfer pipes having thermal
conductivity greater than 100 times the thermal conductivity of
silver and approximately negligible heat loss along said heat
transfer segment.
54. The superconductor defrosting element of claim 50, wherein said
defrosting heat exchange segment is arranged as a condenser array
approximately conforming to the area of the blower.
55. The superconductor defrosting element of claim 49, wherein at
least a portion of said thermal superconductors are formed in
discrete segments joined by approximately short thermally
conducting joiners.
56. The superconductor defrosting element of claim 49, further
comprising a tray located below said defrosting element and a
drainage line coupled to said tray for the collection and transfer
of water produced by the defrosting of ice built up on said
superconductor defrosting element.
57. The superconductor defrosting element of claim 49, further
comprising an ice buildup sensor located approximately at said
refrigerating heat exchange segment and connected to said
controller, wherein a defrost cycle is selected upon said sensor
reaching a programmed setpoint
58. The superconductor defrosting element of claim 57, further
comprising an optical sensor to detect ice build up on heat
exchangers.
59. The superconductor defrosting element of claim 57, further
comprising an air pressure sensor to detect ice build up on heat
exchangers.
60. The superconductor defrosting element of claim 57, further
comprising thermal sensor to determine the rate of heat transfer to
or from said element through said superconductor heat transfer
pipe.
61. The superconductor refrigerating system of claim 50, further
comprising an enclosure which houses said defrosting heat exchanger
and said blower.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to refrigeration
systems, and more particularly to a refrigeration heat exchanger
having a superconducting heat transfer element.
BACKGROUND OF THE INVENTION
[0002] Commercial refrigeration systems typically use a
phase-change refrigerant to absorb heat from an interior space and
move it to an exterior space where it can be rejected. The
refrigerant in these typical systems is circulated in a refrigerant
loop connecting a refrigerating heat exchanger (or "evaporator")
which absorbs heat from a space to be cooled, a compressor which
intensifies this heat, and a heat dissipating heat exchanger (or
"condenser") which dissipates the heat either into the outside
environment or into a building mechanical system that requires
heat, such as a domestic hot water system.
[0003] In a typical application such as a walk-in freezer with a
roof-top heat dissipating heat exchanger, the refrigeration process
works in the following manner. Liquid refrigerant flows through the
refrigerant loop and into the evaporator where it rapidly drops in
temperature as it expands to fill the larger volume of the
evaporator, becoming a supercooled partial liquid. As the droplets
in the partial liquid contact the inner surfaces of the evaporator
coil they absorb heat and rapidly evaporate, cooling the surfaces
of the evaporator to a temperature lower than the air in the
freezer. The cooled surfaces then absorb heat from the air as it is
drawn across the surfaces by a fan. The cooled air then returns to
the space, cooling the space. The evaporated refrigerant then flows
out of the evaporator, through the refrigerant loop, and into the
compressor where it is compressed, causing the heat contained in
the vapor to be intensified. The hot vapor then flows through the
loop to the roof-top condenser which becomes hot. Air drawn across
the outer surfaces of the condenser absorbs this heat and carries
it off into the atmosphere. This loss of heat causes the
refrigerant vapor to condense into a liquid. The liquid refrigerant
then flows back to the evaporator to begin the heat removal process
again.
[0004] Many variants of this process have been developed to serve
different refrigeration requirements, but the process remains
similar. In some systems, the roof-top heat dissipating heat
exchanger is replaced with a heat exchanger inside the building,
with air ducts coming into and going out of the building for the
purpose of rejecting heat into the outside atmosphere. In other
systems, the roof-top heat exchanger is replaced with a
refrigerant-to-water heat exchanger inside the building, which
transfers heat from the refrigerant loop to a water loop, such that
heat can be rejected into an outdoor evaporation pond or employed
by a building mechanical system to provide hot water for space
heating or domestic hot water purposes. Similarly, the
refrigerating heat exchanger can absorb heat from a liquid such as
water in an ice making machine instead of from the air in a space.
In these variations, the method of heat exchange at the
refrigerating and dissipating heat exchangers varies, but the
refrigeration circuit remains the same. Typically, the
characteristic rating of the refrigerant is matched to the
application.
[0005] In large refrigeration systems, this process has a number of
inherent problems and inefficiencies.
[0006] Commercial refrigerators are often large and far away from
the refrigeration plants that serve them, so the loops are often
very long and have large volumes of refrigerant and large numbers
of connections and valves, which makes them vulnerable to leaks and
causes them to require frequent maintenance of components.
[0007] The complexity of large circulating refrigerant systems
makes it difficult for the heat absorbed in one refrigerator to be
employed to defrost the heat exchanger in another or to supplement
other building mechanical systems requiring heat. This results in
low energy efficiency.
[0008] The movement of refrigerant over long distances requires
significant pumping energy, which decreases system energy
efficiency.
[0009] In the refrigeration cycle, cold refrigerant passes through
loops in the evaporator, absorbing heat from the evaporator as it
passes through. As a result, each loop naturally has a temperature
gradient--colder at the refrigerant inlet and warmer at the
refrigerant outlet. This means that parts of the evaporator are
warmer than others, making them less able to absorb heat from the
air, resulting in lower evaporator efficiency, and requiring an
increase in heat exchanger size to compensate.
[0010] In air-to-refrigerant heat exchangers operated in the
refrigeration mode, the cooling process causes moisture from the
air to condense and freeze on the surfaces of the closely packed
fins and tubes that make up the evaporator. Eventually this ice
build-up blocks air-flow through the evaporator, reducing
efficiency. When efficiency drops below an acceptable level, the
ice is removed through a defrost cycle, most commonly achieved by
reversing the refrigeration system to provide heating instead of
cooling to the refrigerating heat exchanger.
[0011] Defrosting results in three problems. First, the reversing
valves employed to reverse the flow of refrigerant in the system
are inefficient and prone to failure. Second, the reversal of the
system from refrigeration to defrost causes refrigerant to behave
differently from it's prior phase at a location in the loop,
condensing where it previously evaporated, evaporating where it
previously condensed; compensating for these changes in behavior
requires additional system complexity, cost and maintenance.
Second, frequent cycling from cold to hot causes stress on
connections which causes leaks. Third, the defrost cycle requires
the whole refrigeration system to be stopped, gradually reversed to
decrease heat stress, operated in reverse long enough to defrost
the refrigerating heat exchanger, stopped, and then gradually
reversed to decrease heat stress before returning to the
refrigerating mode; this creates a transition time, and during this
time the space is not being refrigerated, leading to a rise in
space temperature that can be compensated for with high levels of
refrigeration energy when the refrigeration mode becomes
operational again, causing the whole refrigeration system to
require higher refrigerating capacity. Other systems have been
developed to achieve shorter defrost times but each has inherent
problems. Electrical resistance strip heaters for example, have
been mounted to the face of evaporator coils, allowing the primary
refrigeration system to simply stop while the secondary electrical
system provides defrost energy. These strip heaters are prone to
burning out, requiring frequent replacement which can be done if
the strips are mounted to the accessible face of the evaporator
unit. This causes them to be inefficient because they are far away
from the ice mass, which at the core of the evaporator.
[0012] There is a need for a refrigeration system that operates
without a refrigerant transfer loop, utilizes much less power than
conventional refrigerators, has smaller heat exchangers, has an
extended lifetime due to fewer parts, uses less refrigerant, has a
shorter and more efficient defrost cycle and provides enhanced
refrigeration efficiency per unit power. There is further a need
for a non-refrigerant based defrosting element for use in
combination with a conventional refrigeration system.
SUMMARY OF THE INVENTION
[0013] A refrigeration system incorporates thermal superconducting
heat transfer. The system includes an intensifying heat exchanger,
a refrigerating heat exchange coil formed from thermal
superconductor material, and a dissipating heat exchange coil
formed from thermal superconductor material. The system can include
a switch connected to condenser and evaporator heat exchange
segments, a refrigeration switch segment and a dissipating switch
segment such that in a first switch position a refrigerating mode
is provided and in a second switch position a defrost mode is
provided. Additional embodiments include thermostat controllers and
blowers for enhanced control. Heat exchange and reuse is described
for multiple heat exchangers coupled by thermal superconductors. A
defrosting element is described for refrigeration heat
exchangers.
[0014] In one embodiment, a refrigeration system having thermal
superconducting heat transfer includes a reversible intensifying
heat exchanger, having a compressor, a refrigerating heat exchange
coil formed from thermal superconductor material, and a dissipating
heat exchange coil formed from thermal superconductor. The
refrigeration system also has a reversing valve that can be
configured to provide corresponding refrigerating or defrosting
modes of the superconductor refrigeration system. The refrigerating
or defrosting modes can be selected by a thermostat controller for
the purpose of operating in a refrigerating or defrosting mode to
refrigerate a space.
[0015] In a further embodiment, a defrosting system having thermal
superconducting heat transfer includes an intensifying heat
exchanger, a defrosting heat exchange coil formed from thermal
superconductor material, an absorbing heat exchange coil formed
from thermal superconductor material, and a controller programmable
to a desired set point and further having a thermostat controller
connected to the thermal switch and compressor.
[0016] In a further embodiment, a superconductor refrigeration
exchange element includes a plurality of evaporator refrigerant
conduits suitable for receiving refrigerant; an evaporator coupled
to ends of each of the plurality of refrigerant coils, a condenser
conduit coupled to opposing ends of each of the plurality of
refrigerant coils; a plurality of cooling plates formed of a
thermally conductive material arranged in a approximately co-planar
stack, and having at least one conduit opening through each of the
plates corresponding to each refrigerant conduit such that the
conduits are seated in thermal contact within the cooling plate
stack for the purpose of exchanging heat with air; a thermal
superconductor heat transfer pipe arranged such that a coupling
portion is coupled on at least one side of the cooling plate stacks
such that thermal contact is created between the cooling plates and
the heat transfer pipe. The location of the coupling portion
relative to the seated conduits is arranged to increase available
air flow through the plates, and a transfer portion extends away
from the stack of plates. In addition, insulation surrounds at
least part of the extended transfer portion to reduce heat transfer
loss. Heat is transferred from the cooling plates by the
refrigerant conduits for the purposes of cooling the air flow and
heat is transferred to cooling plates by the thermal superconductor
heat transfer pipe for defrosting ice build up on the cooling
plates such that the air flow is approximately maintained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1a is a schematic diagram of a refrigeration system
with thermal superconductor heat exchangers and a reversible
superconductor transfer switch enabling the system to switch from
refrigeration to defrost. FIG. 1b is an enlarged view of the
intensifier heat circuit.
[0018] FIG. 2 is a schematic diagram of a refrigeration and defrost
system with thermal superconductor transfer segments coupled to a
heat intensification circuit by independent thermal transfer
switches.
[0019] FIG. 3 is a schematic diagram of a refrigeration and defrost
system with multiple thermal superconductor heat exchangers coupled
with independent thermal transfer switches to a single heat
intensification circuit.
[0020] FIG. 4 is a schematic diagram of a refrigeration and defrost
system using a liquid heat exchanger as a heat source or heat
sink.
[0021] FIG. 5 is a schematic diagram of a refrigeration and defrost
system using superconductor heat exchangers with blowers and a
reversing valve to switch the system from refrigeration to
defrost.
[0022] FIG. 6 is a schematic diagram of a refrigeration and defrost
system using multiple superconductor heat exchangers with blowers
and a reversing valve to switch the system from refrigeration to
defrost.
[0023] FIG. 7 is a schematic diagram of a defrost system using
superconductor heat exchangers.
[0024] FIG. 8a is a schematic diagram of a defrost system using a
heat intensification circuit and a superconductor heat exchanger to
draw waste heat from the hot vapor line of a conventional
refrigeration system.
[0025] FIG. 8b is a schematic diagram of a defrost system using
waste heat indirectly from the hot vapor line of a conventional
refrigeration system through a liquid heat exchange fluid.
[0026] FIG. 8c is a schematic diagram of a defrost system using
waste heat from a circulating fluid from another heat generating
system.
[0027] FIG. 9a is a schematic diagram of a defrost system using a
superconductor heat exchanger to draw waste heat directly from the
hot refrigerant line of a conventional refrigeration system without
the assistance of a heat intensification circuit.
[0028] FIG. 9b is a schematic diagram of a defrost system using
waste heat indirectly from the hot vapor line of a conventional
refrigeration system through a liquid heat exchange fluid, without
the assistance of a heat intensification circuit.
[0029] FIG. 10 is a schematic diagram of a defrost system using a
superconductor heat exchanger to draw waste heat directly from the
hot refrigerant line of a conventional refrigeration system without
the assistance of a heat intensification circuit.
[0030] FIG. 11 is a schematic diagram of a heat exchanger with
superconductor heat exchange segments.
[0031] FIG. 12a is a cut-away view of a conventional refrigerating
heat exchanger showing the fluid flow path. FIG. 12b is a schematic
diagram of a modified refrigerating heat exchanger with couplable
superconductor defrost heat exchange elements. FIG. 12c is a
schematic diagram of a modified refrigerating heat exchanger with
integrated superconductor defrost heat exchange elements.
[0032] FIG. 13 shows superconductor defrost heat exchange elements
applied to the face of a conventional heat exchanger.
[0033] FIG. 14 shows an elevation of a refrigeration and defrost
system installed in a building where the refrigerated space, the
refrigeration plant and the dissipating heat exchangers are
separated from each other.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
[0034] With reference to the drawings, new devices and systems for
improved refrigeration and defrosting will be described, embodying
the principles and concepts of the present technology.
[0035] Recent advances in thermal superconducting materials can now
be considered for use in novel energy transfer applications. For
example, U.S. Pat. Nos. 6,132,823, 6,916,430 and 6,911,231 and
continuations thereof, disclose a examples of a heat transfer
medium with extremely high thermal conductivity and methods of
manufacture, and are 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, and when suitably configured for refrigeration,
its application results in many significant advantages. The
available product sold by Qu Energy International Corporation is an
inorganic heat transfer medium provided in a vacuum sealed heat
conducting tube. The term superconductor can interchangeably mean
thermal superconductor. For illustrative purposes, this
superconductor can 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 can have
various forms and cross sections such as flexible conduits, thin
laminate, thin film coated metal etc. Optionally, the
superconducting transfer segments can be formed from discontinuous
discrete sections of superconducting material separated by small
gaps of a non-superconducting material.
[0036] An embodiment of the present technology is a refrigeration
system comprised of two subsystems. The first subsystem is a
refrigeration loop which serves to intensify heat energy so it can
be moved. The second subsystem is a heat distribution system that
uses thermal superconductor elements to absorb and dissipate heat
and to move heat through the system without moving parts. These
subsystems can include: [0037] a) two heat exchangers, one hot and
one cold, which can be for example, located in the refrigeration
plant area, to transfer heat energy between the phase change
refrigeration subsystem and the superconductor distribution
subsystem; [0038] b) two or more blowers to draw air across the
heat exchangers to achieve the transfer of heat energy to or from
the heat exchangers; [0039] c) one or more thermal superconductor
switches to allow heat to be directed to or from an individual heat
exchange component or to allow individual heat exchange components
to be isolated from the system; [0040] d) superconductor
distribution components to transfer heating and cooling energy
between the switches and the individual heat exchange components;
[0041] e) superconductor heat exchangers to absorb heat from spaces
to be cooled [0042] f) superconductor heat exchangers to dissipate
excess heat into the atmosphere or transfer excess heat to other
building systems which can use this heat; and [0043] g) thermostats
and programmable controllers to enable the system to sense and
respond to conditions in the refrigeration system.
[0044] The embodiment of the refrigeration system operates in the
following general manner. The phase-change refrigerant subsystem
operates as a local heat intensification circuit, with a "cold"
heat exchanger or "evaporator" which absorbs heat from the heat
distribution subsystem, a compressor which intensifies this heat,
and a "hot" heat exchanger or "condenser" which transfers this heat
back into the distribution subsystem. In a refrigeration mode, the
"cold" heat exchanger is connected by a superconducting heat
transfer element to a superconducting heat exchanger in a space
selected to be cooled (the "refrigeration space"), while the "hot"
heat exchanger is connected by superconducting heat transfer
elements to a superconducting heat exchanger located or coupled for
external heat transfer such as outside a building, by thermal
routing using a superconducting thermal switch in a refrigeration
mode setting. Air from the refrigeration space is drawn by a blower
across the superconducting heat exchanger where heat from the air
is absorbed by the heat exchanger's cold surfaces. The air returns
to the space colder, cooling the space. The heat absorbed from the
air is transferred by the superconducting transfer elements to the
"cold" heat exchanger, then transferred to the refrigerant loop,
intensified and transferred to the "hot" heat exchanger and back to
the thermal switch. The heat is then transferred by superconducting
thermal transfer elements to the dissipating superconducting heat
exchanger. A fan blows air across the heated surfaces of the
superconducting heat exchanger, causing the heat to be absorbed by
the air and dissipated into the atmosphere.
[0045] In a defrost mode, the thermal switch is reversed,
connecting the "hot" heat exchanger to the superconducting heat
exchanger in the refrigeration space, and the "cold" heat exchanger
to the external superconducting heat exchanger outside the
refrigeration space. Heat is absorbed from the external or outside
air by the outside heat exchanger, transferred to the "cold" heat
exchanger, absorbed by the refrigerant loop, intensified,
transferred to the "hot" heat exchanger and then transferred to the
superconducting heat exchanger in the cooled space, heating it up
and melting the ice that has built up on its surfaces.
[0046] Replacing the circulating fluid components of conventional
heat distribution systems with thermal superconductor components
has a number of advantages that overcome the limitations described
in the background. First, thermal superconductors as described
herein have no moving parts, except as configured as thermal
switches for routing heat. Second, thermal superconductors have the
capacity to transfer heat over relatively long distances with
limited energy loss and without the assistance of mechanical
pumping. Third, the superconductors transfer heat bi-directionally
so the system can be changed quickly from refrigeration to defrost
with limited stress on system components and without changing the
direction of the circulation of the conventional refrigeration
loop. Fourth, they can be arranged to allow heat to be transferred
more uniformly across heat exchangers, making these heat exchangers
more efficient and therefore potentially smaller than conventional
circulating phase change heat exchangers.
[0047] Limiting the function of the conventional phase change
refrigeration loop to the intensification of heat has several
advantages. First, it allows the phase change refrigeration
subsystem to be contained within the refrigeration plant area of a
building, making it smaller and less complicated than in a
conventional refrigeration system because large volumes of
refrigerant are not required to be circulated over long distances.
Second, in the preferred embodiment, it allows the phase change
refrigeration subsystem to operate in the same direction in both
refrigeration and defrost cycles, eliminating reversing valves,
many of the thermostatic expansion metering valves, most of the
circulating refrigerant in the system and most of the reservoirs
required in a reversing system to handle excess liquid refrigerant.
Third, it eliminates refrigerant leaks outside the central
refrigeration plant area and makes the system easier to service.
Fourth, the elimination of unreliable components, extends system
lifetime and reduces system maintenance.
[0048] In addition to the foregoing technical advantages, this
refrigeration system (in its various embodiments) shows significant
operational advantages over conventional refrigeration systems.
First, it allows heat energy to be moved from one heat exchanger to
another in the system so that waste heat produced by a
refrigeration unit can be employed to defrost the heat exchanger in
another refrigeration unit. Second, it allows waste heat to be
moved to and from other building mechanical systems such as air
heat, floor heat, snow melt, domestic hot water and grey water. And
third, with correct switching, this system allows refrigeration
units to provide space cooling without the use of mechanical
compression whenever outdoor temperatures are low enough to be
practicable.
[0049] FIG. 1a illustrates an embodiment of refrigeration system
110 in which heat is transferred bi-directionally using a thermal
superconducting medium in the manner described generally above.
[0050] Specifically, an intensifier heat circuit forms a
refrigerant transfer path which includes a compressor 24 having
outlet connected by refrigerant conduit 19 to a condenser heat
exchanger 21 connected to an evaporator conduit 23 connected to a
expander 26 connected via conduit 27 to an evaporator heat
exchanger 28 connected to a return conduit 29 and an optional
accumulator 30 connected by a return conduit 31 to the inlet of the
compressor 24. The compressor is controllable through control line
22 connected to controller 16. As is well known in the art, the
condenser heat exchanger gives up heat and the evaporator heat
exchanger absorbs heat, referred to, respectively, as hot and cold
intensifier exchangers, for the purpose of delivering higher grade
heat. The compressor 24 compresses a gaseous refrigerant to
intensify its heat content, circulates it through conduit 19 to the
condenser heat exchanger 21 where it gives up heat and condenses to
a liquid or partial liquid, and then passes through conduit 23 to
expander 26 which rapidly expands the liquid in a pressure drop
causing the refrigerant to become a supercooled partial liquid
which absorbs heat and evaporates in the evaporator heat exchanger
28 before passing through return conduit 29 to optional accumulator
30 (where excess remaining liquid is trapped and evaporated) and
remaining refrigerant passes through conduit 31 to complete the
loop at the compressor inlet. This heat intensifier circuit is for
the purpose of converting low grade heat to high quality heat such
that heat is transferred at a faster rate. An apparatus for
intensifying heat can equivalently substitute for the refrigerant
based heat intensifier circuit illustrated. When the refrigerant
loop as described is filled with a suitable amount of refrigerant,
the intensifier circuit is operated by turning the compressor on.
This creates a temperature differential between condenser heat
exchanger 21 and evaporator heat exchanger 28. In the preferred
case, the intensifier heat exchangers are isolated by insulation
25. Superconductor segment 32 is coupled to condenser heat
exchanger 21 and superconductor segment 34 is coupled to evaporator
heat exchanger 28, and both superconductor segments terminate on an
input side of 2.times.2 thermal switch 36 connected to control line
20.
[0051] The thermal switch functions to selectively couple the
intensifier heat exchangers to refrigeration space heat exchanger
42 (associated with a partially or fully closed space to be
refrigerated) and external heat exchanger 42a (in an environment
external to the refrigerated space.) A high efficiency thermal
switch design is described in a related United States Patent
Application "Geothermal Exchange System Using a Thermally
Superconducting Medium," filed Sep. 14, 2006, incorporated herein
for reference. Alternately, the thermal switch can be made of other
thermally conductive material such as copper or silver alloys with
resulting higher losses. For short transfer distances, segments 32
and 34 can equivalently be a non-superconducting heat transfer
medium with a resulting small loss in overall efficiency. In the
preferred embodiment the thermal superconductor pipes 32 and 34 are
coupled to heat exchangers 21 and 28 respectively by direct contact
including spot welding the two components side by side along a
suitable "transfer length" or forming both such that a substantial
contact areas of the two components can be clamped or joined. The
heat intensifier circuit is for the purpose of converting low grade
heat to high quality heat such that heat is transferred at a faster
rate. An apparatus for intensifying heat can equivalently
substitute for the refrigerant based heat intensifier circuit
illustrated.
[0052] The first of two remaining inputs of the thermal switch 36
is connected to thermal superconductor transfer segment 38, which
is connected to refrigeration space heat exchange coil 42 within a
space to be cooled. A thermal sensor 18 is associated with the air
to be conditioned by refrigeration space heat exchange coil 42. A
controller 16 is powered by power line 14 and provides power to
compressor 24 and thermal switch 36, as well as control data to and
from thermal switch 36, blowers 55 and 55a and thermal sensors 18
and 18a through respective control lines 52 and 52a. As will be
appreciated, variations of this example can include independently
connected compressor or blower power or multiple control systems
without changing functionality. Refrigerating heat exchange coil 42
can be configured in a geometric arrangement to improve heat
transfer to a specific medium. Insulation 25 preferably covers
superconductor transfer segments outside of coupling connections
and heat exchange sections, to reduce thermal transfer losses. The
last remaining input of the thermal switch 36 is connected to
thermal superconductor transfer segment 40 which is connected to
external heat exchanger 42a. A thermal sensor 18a is associated
with the air to which external heat exchanger 42a transfers heat.
Controller 16 provides control data to and from thermal sensor 18.
External heat exchange coil 42a can be configured in a geometric
arrangement to improve heat transfer to the air.
[0053] The refrigeration heat exchange system 110 is operated in
either a refrigeration or a defrost mode. The refrigeration mode
operation can be determined in proportion to the difference between
a refrigeration set point and the measured temperature from sensor
18. Defrost mode can be programmed for periodic maintenance based
on empirical understanding of ice buildup, or an additional ice
buildup sensor (not shown) can be added with a set point that
triggers defrost mode, for example an optical displacement sensor
or air pressure sensor common in the industry. In refrigeration
mode, thermal switch 36 is controlled to couple superconductor 38
to cool segment 34 and to couple superconductor 40 to hot segment
32. Controller 16 operates compressor 24 which comprises part of a
heat intensification circuit. Blower 55 draws air across the cold
surfaces of refrigeration space exchanger 42 causing heat to be
absorbed from the air. Thermal superconductor transfer segment 38
then transfers this heat to the intensifier circuit where it is
intensified and then transferred by superconductor transfer segment
40 to external superconductor heat exchange coil 42a. Blower 55a
then draws air across the heated surfaces of heat exchange coil 42a
causing heat to be absorbed into the air and dissipated into the
atmosphere outside the space to be cooled. The blower can be local
and dedicated to the refrigeration system shown, or can
alternatively be shared or provided as a separate room circulating
system having the refrigeration space heat exchanger positioned
suitably in the flow path, for example fans embedded in a wall
pushing air past suspended heat exchangers.
[0054] In defrost mode, thermal switch 36 is controlled to reverse
the thermal couplings and heat transfer such that refrigeration
space heat exchanger becomes heated and external heat exchanger
absorbs heat, i.e. they reverse functions compared to refrigeration
mode. Superconductor 38 is coupled to hot segment 32 and
superconductor 40 is coupled to cold segment 34, and controller 16
operates compressor 24,which comprises part of a heat
intensification circuit. Heat is then absorbed from air drawn by
blower 55a across the cooled surfaces of external heat exchange
coil 42a and then transferred through superconductor transfer
segment 40 to the intensifier circuit and intensified, then
transferred through superconductor transfer segment 38 to
refrigeration space exchange coil 42, causing it to heat up and
melt ice that has built up on its surfaces. Melted water is then
collected in drip tray 56 and drained away through condensate drain
line 58 to a suitable location. Sensor 18 can be located for
effective monitoring of degree of melted ice on the heat exchanger,
or an additional defrost sensor (not shown) can be included and
connected to controller 16. The modes can simply switch on/off or
alternatively oscillate between refrigerating and defrosting based
on programming of controller 16, however as is evident from FIG. 1,
the modes are mutually exclusive as relates to a system with a
single refrigeration space heat exchanger and a single external
heat exchanger.
[0055] The intensifier circuit can have additional components as
required to scale for larger energy applications, for example where
the refrigeration space is very large and partially open for
storage access. As shown in FIG. 1b for an expanded alternate
arrangement of a large scale intensifier circuit, such larger
systems can have receivers 33, suction accumulators 30, bulb
sensors 17, thermostatic expansion metering valves 15 and the like
to manage refrigerant flow through the heat intensification
circuit, as known in the art of conventional heat pump systems.
[0056] Using the preferred thermal superconducting tubes, it is
preferred to have insulation 25 along the length of superconductor
segments except heat exchanger coil segments or thermal transfer
couplings to other components, to limit heat loss and condensation
buildup. However alternate thermal superconductor embodiments can
have integrated insulating layers or have acceptable transfer loss
such that the refrigerating heat exchange system 110 is operable
with less or no external insulation.
[0057] The refrigerating heat exchange system 110 can be enclosed a
number of ways, depending on application. The components can be
housed inside one enclosure to comprise a unit refrigerator.
Alternatively, as shown in FIG. 1, the heat intensifier circuit,
switch and controller can be housed in a housing 12 (such as a room
in a building), and superconductor heat exchange coils 42 and 42a
can be housed in separate enclosures 60 and 60a respectively, as
would typically be found in a large industrial refrigeration
application where the refrigeration plant, the space to be cooled
and the outdoor location for the dissipation of heat are at a
significant distance from each other. In another alternative
embodiment, the heat intensifier circuit can be enclosed in either
enclosure 60 or 60a with superconductor heat exchange coils 42 or
42a respectively, such as is found in conventional "split" systems.
As is well known in the art of controlling mechanical systems,
controller 16 and sensors 18 and 18a can be equally enclosed within
enclosures 12, 60 or 60a, or located outside these enclosures and
connected either wirelessly or by wires to other associated
components in refrigerating heat exchange system 110. Similarly
controller 16 can be remotely programmed through wired or wireless
communications.
[0058] FIG. 2 illustrates an embodiment of the present technology
in which discrete two state superconducting thermal switches 64 and
64a replace the function of reversing switch 36 of FIG. 1, shown as
refrigeration system 120. Each thermal switch 64 and 64a can couple
to both of the hot or cold intensifier heat exchangers 21 and 28,
dependent on control signals sent via control lines 20 and 20a from
the controller. In refrigerating mode, thermal switch 64 is set so
that one of the two illustrated branches of cold superconductor
transfer segment 34 is coupled with superconductor transfer segment
38 such that heat absorbed from a space by refrigeration space
exchanger 42 is transferred to cold heat exchanger 28, and thermal
switch 64a is set so that one of the two illustrated branches of
hot superconductor transfer segment 32 is coupled with
superconductor transfer segment 40 such that heat absorbed from hot
heat exchanger 21 by superconductor transfer segment can be
transferred to external heat exchanger 42a and dissipated into the
atmosphere. In defrost mode, thermal switches 64 and 64a are set in
reverse position such that heat absorbed by dissipating heat
exchanger 42a can be transferred through the system to
refrigeration space exchanger 42 for the purpose of melting
built-up ice. For system 120 to operate, switches 64 and 64a can be
set oppositely, so that one couples to hot heat exchanger 21 and
one couples to cold heat exchanger 28, as controlled by controller
16. Refrigeration system 120 can be similarly housed and programmed
for response to the associated thermal sensors, as system 110, with
the additional modification of the switching arrangement.
[0059] Typical industrial refrigeration applications require
distributed cooling and shared dissipation configurations, which
are easily enabled by the teachings of the superconductor
refrigeration system 130 shown in FIG. 3. FIG. 3 illustrates an
embodiment of the present technology in which a plurality of
refrigeration space exchangers 42, 42a, are coupled to a plurality
of thermal switches 64, 64a respectively, and external heat
exchanger 90 is coupled to additional thermal switch 64b. In this
embodiment, switches 64, 64a and 64b can be independently
configured so that each of heat exchangers 42, 42a and 90 operate
as either heat absorbing or heat dissipating, subject to at least
one of the heat exchangers being coupled to hot heat exchanger 21
and at least one being coupled to cold heat exchanger 28 to provide
a limited thermal balance. Thermal switches are controlled through
control lines 20,20a and 20b as shown, to couple heat to and from
the superconductor transfer segments 38, 38a and 62 respectively.
External heat exchanger 90 includes blower 88 and thermal sensor 84
connected to control line 82 and enclosed in housing 86. In this
embodiment for a refrigerating mode, refrigeration system 130 can
be set so that heat exchangers 42 and 42a operate as refrigeration
space exchangers and heat exchanger 90 operates as a external heat
exchanger. Alternatively, heat exchanger 42 can be set to operate
as a refrigeration space exchanger with heat exchangers 42a and 90
set to operate as dissipating heat exchangers such that heat
exchanger 42 refrigerates while heat exchanger 42a defrosts. Note
that in this previous case the terminology external has dropped and
the term dissipating heat exchanger is used, since within this
context heat can be exchanged with another refrigeration space heat
exchanger operating in defrost mode rather than an external heat
dissipation in ambient atmosphere. In this mode of operation, heat
absorbed by heat exchanger 42 is transferred to the heat
intensification circuit and then to heat exchanger 42a for the
purpose of defrosting build up of ice. This enables refrigeration
system 130 to reuse waste heat produced by at least one
refrigeration space exchanger. In another mode of operation, one of
heat exchangers 42, 42a can be disconnected from the heat
intensification circuit by positioning corresponding switch 64 or
64a in an off position, allowing the disconnected heat exchanger to
be serviced or inoperable while the connected heat exchanger
continues to refrigerate or defrost. The modes of operation can, as
before, be programmed to respond to periodic timing, or in response
to environmental temperature changes in the associated thermal
sensors, or by external controls or stimulus as required to improve
the refrigeration and defrost cycles, and overall system
efficiency. The flexibility of this system configuration represents
a significant advance over conventional systems, by reducing mode
switching response times through elimination of refrigerant
reversal and reusing transferred energy not recovered otherwise,
and permitting simultaneous concurrent defrost and refrigeration
using the same intensifier circuit.
[0060] As shown in refrigeration system 140 in FIG. 4, the
integrated multiple heat exchangers illustrated in system 130 can
have extended functionality by adding a thermal storage or ballast
with heat exchange functionality. A plurality of
air-to-superconductor heat exchangers are independently coupled
through thermal switches 64, 64a and 64b to a heat intensification
circuit, and fluid-to-superconductor heat exchanger 104 is also
coupled to the circuit by thermal switch 64c through superconductor
transfer segment 106 such that the heat exchangers can
independently operate to absorb or dissipate heat, subject to at
least two of the heat exchangers being coupled to the heat
intensification circuit, and at least one of the coupled heat
exchangers being set in heat absorption mode and at least one of
the coupled heat exchangers being set in heat dissipation mode.
Fluid to superconductor heat exchanger 104 is configured within a
liquid storage tank 98 filled with liquid 94 such as water or a
solution with high heat capacity, and having associated temperature
sensor 96 connected to controller 16 by line 108, to provide
feedback on the temperature of the stored liquid. In the preferred
embodiment, one of the heat exchangers, for example heat exchanger
90, is external to the refrigeration space. In a heat storage mode
selected by controller 16 in response to programming and/or
temperature measurements, excess heat absorbed by one or more
air-to-superconductor heat exchangers 42, 42a and 90 can be
transferred to fluid-to-superconductor heat exchanger 104 for
transfer to fluid 94, either for storage in tank 98 or for use by a
separate mechanical system (not shown) which circulates fluid 94
into tank 98 through fluid inlet 100 and out of tank 98 through
fluid outlet 102. In a heat recovery mode, thermal switches of
refrigeration system 140 can be set so that heat in fluid 94 can be
absorbed by fluid-to-superconductor heat exchanger 104 and
transferred to the heat intensification circuit and then
transferred to one or more of the air-to-superconductor heat
exchangers for the purpose of defrosting or alternatively for space
heating. The refrigeration system with heat storage functionality
is well-suited for time varying non-uniform utilization of one or
more refrigeration spaces, and is enabled by bi-directional heat
transfer using thermal superconductors.
[0061] The embodiments shown in FIGS. 1 to 4 are preferred
implementations for systems that both refrigerate and defrost.
However, there is a key substitution that could be made that would
still be improved over existing refrigeration systems but have
fewer operating modes with the tradeoff of using a less reliable
component--a reversing valve. The refrigeration systems in FIGS. 1
to 4 can be modified by adding reversing valve 77 in the
intensifier circuit and eliminating thermal switches as shown in
the refrigerating heat exchange system 150 of FIG. 5, to create a
reversible heat intensifying loop as is well known in the art. In
this embodiment, refrigerant vapor is compressed by compressor 24
and then flows through conduit 19 to reversing valve 77. The
reversing valve, controlled by controller 16 through control line
20, then directs this vapor to either of heat exchanger 70 or 74,
according to whether heating or cooling is required.
[0062] If refrigeration is required for refrigerating heat
exchanger 42, controller 16 sends an instruction to reversing valve
77 to actuate to a position such that heated refrigerant vapor is
transferred from conduit 19 to conduit 75. The refrigerant then
flows to heat exchanger 74, which functions as a condensing heat
exchanger. Heat exchanger 74 gives up heat to superconducting heat
transfer segment 40 which transfers it to external heat exchanger
42a in heat dissipating mode, located outside the space to be
cooled. The refrigerant gas flowing through heat exchanger 74
condenses in the process of giving up heat, forming a liquid or
partial liquid which is transferred through conduit 73 to
bidirectional expansion element 72 which causes liquid refrigerant
to become a supercooled partial liquid before flowing through
conduit 71 to heat exchanger 70, where it absorbs heat from
superconducting transfer segment 38 which transfers heat from
refrigeration space heat exchanger 42. The design of expansion
element 72 for use in both circulation directions is well-known.
The warmed refrigerant gas then passes through conduit 76 and then
through reversing valve 77 which, in the selected position for this
mode, transfers it through conduit 29 to optional accumulator 30
which traps and then allows to evaporate excess remaining liquid
refrigerant before the refrigerant vapor returns through conduit 31
to compressor 24 to begin the heat intensification cycle again. As
described previously controller 16, controls operation of
refrigeration mode through feedback from temperature sensor 18
and/or 18a, or associated external stimulus, by operating the
compressor and reversing valve.
[0063] If defrost is required, controller 16 sends an instruction
to reversing valve 77 to actuate to a position such that heated
refrigerant vapor is transferred from conduit 19 to conduit 76. The
refrigerant is then transferred to heat exchanger 70 which then
functions as the condensing heat exchanger. Heat exchanger 70 gives
up heat to superconductor heat transfer segment 38 which transfers
heat to refrigeration space heat exchanger 42 where this heat melts
ice built up on the surfaces of the heat exchanger. The refrigerant
gas flowing through heat exchanger 70 condenses in the process of
giving up heat, forming a liquid or partial liquid which is
transferred through conduit 71 to bidirectional expansion element
72 which causes liquid refrigerant to become a supercooled partial
liquid before flowing through conduit 73 to heat exchanger 74,
where it absorbs heat from superconducting transfer segment 40
connected to external heat exchanger 42a which absorbs heat from
the air drawn across it by blower 55a. The heated refrigerant vapor
then passes through conduit 75 and then through reversing valve 77
which, in the selected position for this mode, transfers it through
conduit 29 to optional accumulator 30 which traps and then allows
to vaporize excess remaining liquid refrigerant before the
refrigerant vapor returns through conduit 31 to compressor 24 to
begin the heat intensification cycle again. This system has the
advantages of using well known components for switching modes in
the intensification circuit; however it is noted that for larger
intensification circuits designed for large scale heat capacity,
the volume of refrigerant inhibits reversal and creates a delay
time during which the system is inoperable or inefficient. This
effect is reduced relative to a full conventional circulation.
[0064] Refrigeration system 160 in FIG. 6 expands system 150 to
include a plurality of refrigeration space heat exchangers 42 and
42a. In this embodiment, superconductor transfer segment 38 becomes
a thermal bus which, in the refrigerating mode, transfers heat from
refrigerating heat exchangers 42 and 42a to heat exchanger 70, and
in the defrost mode transfers heat from heat exchanger 70 to
refrigeration space heat exchangers 42 and 42a for the purpose of
melting build up of ice. Superconductor external heat exchanger 90
is directly connected to intensifier heat exchanger 74 by
superconductor thermal transfer pipe 40 and operates in dissipating
or absorbing modes depending on direction of the intensifier
circuit.
[0065] This embodiment provides the basic operational modes of
refrigeration and defrost such that the bussed refrigeration space
heat exchangers 42 and 42a are fixed in identical modes. Therefore,
because refrigerating heat exchanger 42 and heat dissipating heat
exchanger 42a are not separately switched as shown in FIGS. 1 to 4,
no other operating modes described for FIGS. 1 to 4 are
enabled.
[0066] All refrigerating systems shown in FIGS. 1 to 6 operate in
both refrigeration and defrost modes, and in some cases mixed
modes. In some applications a system will not have both
refrigerating and defrost modes. One such application is in the
retrofitting of existing conventional phase-change refrigerant
systems, where complete replacement would be economically
inefficient. In such an application, some of the most difficult
problems of reversing phase change systems could be eliminated by
the addition of a separate system to handle defrost only. FIG. 7
illustrates such a defrost only system 170. Defrost heat exchanger
42a is permanently coupled by superconducting heat transfer segment
32 to hot heat exchanger 21, and heat absorbing heat exchanger 42
is permanently coupled by superconducting heat transfer segment 34
to cold heat exchanger 28. The coupling of the defrost heat
exchanger to the evaporator is further described in FIGS.
11-13.
[0067] When controller 16 receives a signal from defrost sensor 18a
that ice has built up on an associated evaporator coil (not shown)
of a separate refrigerating system (not shown) or determines that a
programmed periodic defrost cycle is due, controller 16 operates
compressor 24 to activate a heat intensification circuit. Heat is
absorbed from the atmosphere by external heat exchanger 42 and
transfers it by superconductor heat transfer segment 34 to the heat
intensification circuit, which intensifies it and transfers heat by
superconducting heat transfer element 32 to defrost heat exchanger
42a for the purpose of melting ice that has built up on the
associated evaporator coil. As will be obvious to one skilled in
the art of conventional refrigeration systems, sensor 18a can be
alternatively an infrared sensor, a sensor that detects changes in
static pressure of the air being drawn across the evaporator coil
by its associated blower (not shown), or another kind of ice
sensor. Alternatively, the defrost cycle can be initiated by a
timer or other programmed control sequence or by manual switching.
The superconductor defrost exchanger system 170 represents an
advance by enabling a conventional refrigerant system to remain in
one operating mode instead of reversing valve position, eliminating
reversing the trouble prone reversing valve and increasing
reliability and overall operating efficiency.
[0068] FIGS. 8a,b,c illustrates several alternate embodiments
showing superconductor defrost system 180. In these embodiments,
the defrost heat source substitutes a fluid loop 80 connected to a
remote thermal system in place of the external heat exchanger using
air exchange. In a preferred embodiment FIG. 8a, the fluid loop is
the hot refrigerant loop of a conventional refrigeration system. In
this embodiment, the remote conventional refrigeration system (not
shown) operates to remove heat from at least one refrigerating heat
exchanger (not shown). This heat is then transferred through heat
exchanger 77 to the defrost intensifier subsystem by thermal
superconductor pipe 78 which is coupled with low thermal losses.
Heat is then intensified and transferred to defrost heat exchange
segment 42 where it is then transferred to the associated
evaporator coil (not shown) of a conventional refrigerating heat
exchanger for the purpose of melting build up of ice. As will be
obvious to one skilled in the art of conventional refrigeration
systems, the evaporator coil (not shown) receiving the heat from
superconductor defrost system 180 can equally be part of the remote
conventional refrigeration system providing the heat, or part of a
second, separate conventional refrigeration system. In this
process, hot refrigerant gas flows into heat exchanger 77 through
refrigerant inlet 81, gives up heat to superconductor heat exchange
element 78 as the refrigerant passes through condenser coil 80,
condensing in the process, and then flows out of heat exchanger 77
through refrigerant outlet 83. The heat absorbed by superconductor
heat exchange element 78 is transferred by superconductor transfer
segment 34 to the heat intensification circuit where it is
intensified and transferred by superconductor transfer segment 32
to defrost heat exchanger 42. Controller 16 initiates the operation
of the defrost cycle in response to defrost sensor 18, or as
programmed by periodic timing, and operates the compressor until
programmed desired sensor setting is reached, or programmed defrost
duration is reached. For the case of large industrial refrigeration
plants with many dissipating heat exchangers in proximity to
refrigeration spaces, this defrost embodiment solves the problem of
reusing dissipated heat near it's source without increasing ambient
temperatures, rather than transporting it and wasting it. This is
of particular value where high external or internal ambient
temperatures make heat dissipation inefficient
[0069] Also included in FIG. 8a is an optional thermal transfer
bypass route, comprised of superconductor thermal transfer segments
44, 46 and thermal switch 35, which enables superconductor transfer
segments 32 and 34 to be directly thermally coupled as shown, such
that heat is not required to pass through the heat intensification
circuit to transfer between the superconductor transfer segments.
When controller 16 determines by way of heat flow sensor 84 that
the heat content of fluid 94 is sufficient without intensification
for the purpose of melting ice at greater than a programmed
threshold de-icing rate determined by the approximate volume of
ice, evaporator configuration and refrigeration space temperature,
at the refrigerating heat exchanger (not shown) associated with
superconductor defrost segment 42, the controller causes compressor
24 to be stopped if operating, and switch 35 to be set in an "on"
position, causing superconductor transfer segments 32 and 34 to be
thermally coupled, transferring heat directly from superconductor
heat exchange segment 107 to defrost heat exchange segment 42.
[0070] FIG. 8b shows a variant of the defrost system 180 in which a
fluid 94 stores and transfers heat but remains contained within
tank 98. In a preferred embodiment, a separate system (not shown)
causes a heated refrigerant to flow through refrigerant inlet 81
into tank 98, passing through condenser coil 80, giving up heat to
fluid 94 before condensing and flowing out of the tank through
refrigerant outlet 83. Similar to FIG. 4, heat is absorbed by
superconductor heat exchange segment 104 positioned in storage tank
98 and transferred to the heat intensification circuit.
Alternatively, the separate system (not shown) can equally be a
circulating fluid heat transfer system and condenser coil 80 can
equally be a heat exchange coil suited to the purpose of
transferring heat from one fluid to another. A temperature sensor
84 can provide an optional feedback to controller 16 for
information on the heating state and cycle of the fluid 94. A
bypass switch 35 is optionally provided as described
previously.
[0071] FIG. 8c illustrates an alternative embodiment of the defrost
system 180 which uses a directly exchanged fluid such as grey
water, sea water, pond water or the like as the heat source. In
this embodiment, a fluid 94 from a separate system (not shown)
flows into tank 98 through fluid inlet 101 and flows out through
fluid outlet 102. Superconductor heat exchange segment 104 is
located in the storage tank 98 and absorbs heat from the fluid 94
and transfers it by way of superconductor transfer segment 34 to
the heat intensification circuit, where the heat is intensified
before being transferred to defrost heat exchange element 42. A
temperature sensor 96 can provide an optional feedback to
controller 16 for information on the heating state and cycle of the
fluid 94. A bypass switch 35 is optionally provided as described
previously.
[0072] The rapid defrost cycle enabled by the defrost systems shown
in FIGS. 1-8, allows for more frequent defrost cycles for shorter
durations which leads to an increased average air flow path over
the evaporator fins, resulting in improved effective cooling rates
over existing conventional systems which can tradeoff air flow
restriction versus longer defrost downtime.
[0073] FIG. 9a illustrates a simplified alternative embodiment of
the defrost system illustrated in FIGS. 8a, which is operable when
the heat content of the remote hot refrigerant gas flowing through
condenser coil 80 is sufficient, without intensification, for the
purpose of melting ice at the refrigerating heat exchanger (not
shown) associated with superconductor defrost segment 42. During
operation of defrost system 190, heat is absorbed from condenser
coil 80 by superconductor heat exchange segment 78 and transferred
by superconductor transfer segment through thermal switch 35 to
superconductor transfer segment 38 which transfers it to
superconductor defrost segment 42. In operation, controller 16
determines (by timer program or through a signal from ice sensor
18) that defrost heat is required by superconductor defrost segment
42, and closes thermal switch 35, causing heat to flow from heat
exchanger 77 to defrost segment 42. In this embodiment, controller
16 can be located on its own or can be integrated into the
controller of the refrigeration system (not shown) as a separate
function of the refrigeration controller. In an alternate version,
enclosure 12 can be modified to enclose also thermal switch 35, and
have optional fastening features to be mounted to or in the remote
heat exchange module housing 77a. The simplified superconductor
defrost system represents an advance in retrofitting existing
refrigeration systems with limited additional electrical power
required, through operation of a heat exchange system to reuse
available heat, and through very compact installation. Alternate
embodiments of system 190 could of course use the liquid exchange
configurations described in FIGS. 8b, c, including the indirect
liquid heat transfer system shown in FIG. 9b.
[0074] FIG. 10 illustrates an alternative embodiment of the defrost
system, having multiple discrete defrost exchangers. Defrost system
200 shows two defrost exchangers 42 and 42a coupled through
discrete thermal switches 35 and 35a, to the common superconductor
heat exchange pipe 40/40a which terminates in coupling 78 to the
remote heat exchanger 77. In defrost operation, heat absorbed by
superconductor heat exchange segment 78 is transferred by way of
superconductors 40 and 40a to a plurality of thermal switches 35,
35a and then to a plurality of superconductor transfer segments 38,
38a, and finally to a plurality of superconductor defrost segments
42, 42a for the purpose of defrosting ice from evaporator coils
associated with each defrost exchange (not shown). When controller
16 determines by way of heat flow sensor 84 that the heat content
of fluid 94 is sufficient without intensification for the purpose
of melting ice at greater than a programmed threshold de-icing rate
determined by the approximate volume of ice, evaporator
configuration and refrigeration space temperature, at the
refrigerating heat exchanger (not shown) associated with
superconductor defrost segment 42. There can be two thresholds, one
suitable for a single defrost mode operation, and a second higher
heat flow threshold to allow simultaneous heat flow to multiple
defrost exchangers. In an alternate version, enclosure 12 can be
modified to enclose also both thermal switches 35 and pies 40 and
40a, and have optional fastening features to be mounted to or in
the remote heat exchange module housing 77a. In this embodiment,
controller 16 operates switches 35 and 35a independently so that
the defrost segments can be independently coupled to or decoupled
from heat exchanger 77, and the rate and quality of heat exchanged
at heat exchanger is preferably above a threshold for simultaneous
defrosting.
[0075] FIG. 11 illustrates an expanded drawing of one embodiment of
the superconducting heat exchanger 210, as shown in FIGS. 1 to 7.
In this embodiment, refrigeration space heat exchanger 42 is
configured as a superconductor array coupled to optional heat
transfer fins 68 to distribute heat across a larger surface area in
order to transfer heat to the air being drawn across the heat
exchanger by blower 55. In an alternative embodiment, refrigeration
space heat exchanger 42 can be configured with sufficient surface
area such that it can transfer heat as required without the
addition of heat transfer fins. The heat exchanger 42 can be
operated in defrost mode as previously described. An optional drip
tray 56 and drip line 58 is illustrated, including an optional
superconductor branch positioned in the drip tray to defrost the
drip tray. It will be appreciated that the superconductor heat
exchanger can be configured differently from the illustration for
specific installations without changing the functionality. Transfer
segment 38 is shown with thermal insulation 25.
[0076] FIG. 12a-c, illustrate a conventional phase change
refrigeration evaporator with the addition of a superconducting
defrost component, as described previously for FIGS. 8 to 10, to
form refrigerating and defrosting heat exchange unit 220. The
evaporator operates in the conventional manner as part of a
refrigeration system. Liquid refrigerant supply subsystem 66 causes
liquid refrigerant to expand and become a super-cooled partial
liquid as it flows into evaporator loops 69, absorbing heat from
heat transfer fins 67 before flowing out of evaporator loops 69
into refrigerant vapor return subsystem 65 and then back to the
remainder of the refrigeration system (not shown). The heat
transfer fins 67 have additional sleeves 63 enabling superconductor
defrost segment 42 to be inserted for the purpose of delivering
heat to melt ice that has built up on surfaces of the evaporator
assembly. Water produced by the melting of ice is collected in drip
tray 56 (which is also heated by superconductor defrost segment 42)
and is drained away to a suitable location through drain line 58.
FIG. 12a illustrates the conventional evaporator assembly with
other components removed for clarity. FIG. 12b illustrates a
superconducting defrost array 42 couplable and ready for insertion
into sleeves 63 to complete the refrigerating/defrosting heat
exchange unit 220. FIG. 12c illustrates an evaporator unit with
superconducting defrost array 42 permanently installed, or
alternatively, with removable superconducting defrost array 42
inserted for operation. As will be obvious to one skilled in the
art, there are various coupling methods to couple the metal
superconductor pipe to the typically metal fins. The defrost
transfer element 42 represents an increase in the heat transfer
efficiency so that a wide range of couplings and tolerances with
various retrofitted evaporator designs still allows the defrost
system to be enabled. Specifically, the thermal superconductor may
not require bonding, welding or other processes but can simply be
press-fit.
[0077] FIG. 13 illustrates an alternative embodiment of the
modified conventional evaporator system of FIG. 12, configured as
superconductor defrost evaporator system 230. In this embodiment,
superconducting defrost segment 42 is mounted to one side of the
evaporator assembly such that heat from superconducting defrost
segment 42 is transferred to heat transfer fins 67 for the purpose
of melting ice that has built up on the surface of heat transfer
fins 67 and evaporator loops 69. Superconducting defrost segment 42
can alternatively be mounted to both sides of the evaporator
assembly for additional defrost capacity. Superconducting defrost
segment 42 can alternatively be configured to be removable from the
face of the evaporator assembly so as to decrease the wind
resistance to air being blown through the assembly. This example
allows for convenient in-situ installation within the refrigeration
space, without alteration of the conventional refrigeration heat
exchanger.
[0078] FIG. 14 illustrates a typical configuration of refrigeration
system 130 in a building 116. A space to be refrigerated is
enclosed by room 118, having access door 117 such that materials
can be transported in and out. The internal average temperature is
shown as T1. Also within building 130 is a refrigeration plant
enclosed in housing 12, of the type described herein, the internal
temperature outside room 118 is T2. Suspended in refrigerated room
118 are refrigerating heat exchanger housings 60 and 60a which
house refrigerating heat exchange segments, blowers, sensors and
other associated equipment (all not shown) of the superconductor
refrigeration systems. Superconducting heat transfer segments 38
and 38a thermally couple the refrigerating heat exchange segments
with thermal switches 64a and 64b in refrigeration room 12, having
internal temperature T4. Thermal switches are in turn coupled to
both condensing heat exchanger 21 and evaporating heat exchanger
28, which are part of a heat intensification circuit with a phase
change refrigerant fluid (not shown) circulated by compressor 24,
which receives control signals from thermostat controller 16. Heat
absorbed by the refrigerating heat exchange segments (not shown) is
transferred to evaporator heat exchanger 28, intensified by the
heat intensification circuit, transferred by condensing heat
exchanger 21 to thermal switch 64b and then by superconducting
thermal transfer segment 40 to external heat exchanger in housing
86 outside building 116, where this heat is then dissipated into
the atmosphere, having temperature T3. Not shown are additional
refrigeration plants or remote heat exchangers that the illustrated
refrigeration plant can couple to. As previously described,
refrigeration system operates in a refrigerating mode when T1 is
above a programmed thermostat set point. The higher external
temperature T3 is, the blower (not shown) speed can be increased by
controller 16 to adjust the corresponding heat transfer rate to
external air. The external dissipation of heat, maintains internal
temperature T2 at acceptable limits.
[0079] Further, the blower associated with the refrigerating heat
exchanger can be a variable speed controller with speed controlled
by the thermostat controller in response to the difference between
a desired temperature set point and measured temperature of the
refrigeration space. Additionally, the variable speed blower can be
connected to the thermostat controller to enable this control.
[0080] In these examples and embodiments described, insulation has
been shown on superconductor segments designed for low thermal loss
transfer (i.e. not the ends of the superconductor segments), and is
the preferred example, whether or not explicitly stated in figure
descriptions or numbered on drawings. However, as noted previously,
the superconductor geothermal exchange systems described will
operate with no insulation or with some transfer lines insulated or
a combination of insulated or un-insulated portions of the
superconductors thereof.
[0081] In these examples housing has been described as split
housing in a preferred case, however it will be appreciated that
the various embodiments can be integrated into existing structures
or enclosed in a single housing.
[0082] Although particular embodiments of the present technology
have been described by way of example, it will be appreciated that
additions, modifications and alternatives thereto can be envisaged.
The scope of the present disclosure includes a novel feature or
combination of features disclosed therein either explicitly or
implicitly or generalization thereof irrespective of whether or not
it relates to the claimed invention or mitigates one or more of the
problems addressed by the present invention. The applicant hereby
gives notice that new claims can be formulated to such features
during the prosecution of this application or of such further
application derived there from. In particular, with reference to
the appended claims, features from dependent claims can be combined
with those of the independent claims and features from respective
independent claims can be combined in an appropriate manner and not
merely in the specific combinations enumerated in the claims.
* * * * *