U.S. patent number 3,797,270 [Application Number 05/373,851] was granted by the patent office on 1974-03-19 for heat pump with two fluid circuits.
This patent grant is currently assigned to Physikalisch-Technisches Entwicklungsburo Laing. Invention is credited to Nikolaus Laing, Ludwig Ludin.
United States Patent |
3,797,270 |
Laing , et al. |
March 19, 1974 |
HEAT PUMP WITH TWO FLUID CIRCUITS
Abstract
A reversible heat pump, to be used for cooling or heating a
space bounded by a wall, has two rotary heat exchangers coaxially
mounted on opposite sides of that wall and interconnected by a hub
traversing same. The hub includes a highly heat-conductive
partition between the fluid-circulation systems of the two heat
exchangers. A rotary compressor, forming part of the exterior
circulation system, has a housing rigid with the external heat
exchanger and an impeller freely rotatable on a shaft of that heat
exchanger, this impeller being secured to an armature of a
squirrel-cage motor whose field windings are fixedly mounted on the
supporting wall structure. The motor armature and the compressor
are enshrouded by a magnetically permeable cowl forming a rotary
chamber which is filled with a primary heat-carrying fluid, such as
Freon, as well as lubricating oil and which communicates with a
radiator drum on the periphery of the external heat exchanger. A
similar radiator drum on the periphery of the internal heat
exchanger is permeated by a secondary heat-carrying fluid, such as
a low-boiling alcohol, circulating along the thermally conductive
partition in heat-transfer relationship with the primary fluid.
Inventors: |
Laing; Nikolaus (Aldingen near
Stuttgart, DT), Ludin; Ludwig (Anglikon-Wohlen,
CH) |
Assignee: |
Physikalisch-Technisches
Entwicklungsburo Laing (Aldingen bei Stuttgart,
DT)
|
Family
ID: |
4338533 |
Appl.
No.: |
05/373,851 |
Filed: |
June 26, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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198721 |
Nov 15, 1971 |
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Foreign Application Priority Data
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May 30, 1969 [CH] |
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8321/69 |
Nov 14, 1970 [IT] |
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915728/70 |
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Current U.S.
Class: |
62/333; 62/499;
165/86; 165/104.25 |
Current CPC
Class: |
F25B
13/00 (20130101); F25B 3/00 (20130101); F25B
31/002 (20130101) |
Current International
Class: |
F25B
13/00 (20060101); F25B 3/00 (20060101); F25B
31/00 (20060101); F25b 003/00 () |
Field of
Search: |
;62/333,499 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Perlin; Meyer
Attorney, Agent or Firm: Ross; Karl F. Dubno; Herbert
Parent Case Text
This is a continuation of application Ser. No. 198,721, filed Nov.
15, 1971 .
Claims
We claim:
1. A heat pump divided into two portions emplaceable on opposite
sides of a wall for maintaining a temperature differential
thereacross, comprising:
wall-engaging support means;
a first rotary heat exchanger including a hollow first hub
journaled in said support means and a first radiator drum on said
first hub provided with a first set of channels for conducting a
first heat-carrying fluid in heat-exchanging relationship with
ambient air;
a second rotary heat exchanger including a hollow second hub
journaled in said support means coaxially with said first hub and a
second radiator drum on said second hub provided with a second set
of channels for conducting a second heat-carrying fluid in
heat-exchanging relationship with ambient air, said hubs being
coupled for joint rotation and contacting each other along a
thermally conductive partition;
first conduit means in said first heat exchanger for circulating
said first fluid in a closed first flow path between said first set
of channels and said partition;
second conduit means in said second heat exchanger for circulating
said second fluid in a closed second flow path between said second
set of channels and said partition in heat-transferring
relationship with said first fluid by way of said partition;
thermodynamically effective means in said first heat exchanger for
changing the temperature of said first fluid traversing said first
flow path; and
drive means for rotating said heat exchangers with reference to
said support means.
2. A heat pump as defined in claim 1 wherein said first and second
hubs have telescopically interfitted tubular wall portions centered
on the hub axis and together constituting said partition.
3. A heat pump as defined in claim 2 wherein at least one of said
wall portions has a contact surface in engagement with the other
wall portion provided with a lower-melting metallic coating
fusion-bonded onto said other wall portion.
4. A heat pump as defined in claim 2 wherein said wall portions are
substantially frustoconical.
5. A heat pump as defined in claim 2 wherein said support means
comprises a pair of spaced-apart mounting plates perpendicular to
the hub axis, said wall portions being located in the space between
said mounting plates.
6. A heat pump as defined in claim 1 wherein said first radiator
drum is provided with a peripheral channel for accumulation of a
liquid phase of said first fluid, said first conduit means
including a capillary extending from said channel to the interior
of said first hub.
7. A heat pump as defined in claim 1 wherein said first means
includes at least one nozzle within said first hub trained upon
said partition for discharging said first fluid onto same.
8. A heat pump as defined in claim 1, further comprising a
collector for condensed ambient moisture underneath said second
heat exchanger on said second support and drain means for said
condensed moisture passing alongside said hubs from said collector
to said first support for discharge into the atmosphere.
9. A heat pump as defined in claim 8 wherein said drain means
terminates in the vicinity of said second radiator drum for
directing said condensed moisture unto same.
10. A heat pump as defined in claim 1 wherein said drive means
comprises an electric motor with a stator on said first support and
with a rotatable armature inside said first hub electromagnetically
entrainable by said stator, said thermodynamically effective means
including a compressor with two relatively rotatable sections
centered on the hub axis, one of said sections being coupled with
said armature for joint rotation, the other of said sections being
rigid with said first heat exchanger.
11. A heat pump as defined in claim 10 wherein said one of said
sections is an impeller provided with vane means, said other of
said sections being a housing entrainable by said impeller at a
reduced rotary speed.
12. A heat pump as defined in claim 10 wherein said first hub
comprises a magnetically permeable cowl separating said stator from
said armature and enshrouding part of said first flow path.
13. A heat pump as defined in claim 12 wherein said cowl is
spherically curved.
14. A heat pump divided into two portions emplaceable on opposite
sides of a wall for maintaining a temperature differential
thereacross, comprising:
wall-engaging support means;
a hub structure journaled in said support means;
a first and a second rotary heat exchanger including a radiator
drum provided with a set of channels for conducting a respective
heat-carrying fluid in heat-exchanging relationship with ambient
air;
first and second conduit means in said first and second heat
exchangers, respectively, for circulating those fluids through the
channels of their radiator drums in closed first and second flow
paths approaching each other in said hub structure closely enough
to enable effective heat transfer between said fluids;
a compressor in said first heat exchanger for densifying the fluid
thereof traversing said first flow path in one direction while
being bypassed by said first conduit means for passage in the
opposite direction, said compressor having two relatively rotatable
sections located in said hub structure and centered on the axis
thereof; and
drive means for rotating one of said sections with reference to
said support means, the other of said sections being rigid with
said first heat exchanger for laggingly rotating same about said
axis by fluidic entrainment.
15. A heat pump as defined in claim 14 wherein said drive means
comprises an electric motor with a stator on said support means and
with a rotatable armature inside said hub structure
electromagnetically entrainable by said stator, said one of said
sections being coupled with said armature for joint rotation.
16. A heat pump as defined in claim 15 wherein said hub structure
forms a chamber about said compressor included in said first flow
path, said chamber being bounded by a magnetically permeable cowl
separating said armature from said stator.
17. A heat pump as defined in claim 16 wherein said cowl is
substantially spherically curved about said axis, said armature
comprising a squirrel-cage rotor with conductors closely spaced
from said cowl and curved along the inner surface thereof.
18. A thermogenic device comprising:
stationary support means;
a rotatable body provided with a shaft journaled in said support
means, said body forming a hermetically sealed enclosure about a
closed flow path for a heat-carrying fluid;
fluid-circulating means in said body including a compressor with
two relatively rotatable sections in said flow path centered on
said shaft, one of said sections being freely rotatable on said
shaft, the other of said sections being rigid with said body;
and
an electric motor with a stator on said support means and with a
rotor in said enclosure electromagnetically entrainable by said
stator, said one of said sections being mechanically coupled with
said rotor for joint rotation at a relatively high speed whereby
said other of said sections is fluidically driven together with
said body at a relatively low speed, said enclosure including a
magnetically permeable shell separating said stator from said
rotor.
19. A thermogenic device as defined in claim 18 wherein said one of
said sections is an impeller provided with vane means exerting a
reaction torque upon said other of said sections.
20. A thermogenic device as defined in claim 18, further comprising
brake means on said support means for controlling the rotary speed
of said body.
21. A thermogenic device as defined in claim 20 wherein said brake
means comprises an eddy-current generator.
22. A thermogenic device as defined in claim 18 wherein said shell
is spherically curved.
Description
This application is related to copending application Ser. No.
42,018 filed June 1, 1970, now U.S. Pat. No. 3,696,634.
Our present invention relates to a thermogenic device such as a
heat pump, of the general type disclosed in that copending
application, wherein a pair of rotary heat exchangers are coaxially
mounted for joint rotation on opposite sides of a wall across which
a temperature differential is to be maintained. Two heat-carrying
fluids, circulating along closed flow paths in the two heat
exchangers, are in heat-transferring relationship inside a common
hub structure rotatably supported in an opening of the wall. With
the aid of a thermodynamically effective device such as a
compressor in one of the flow paths, serving for the substantially
adiabatic changing of the temperature of the fluid traversing that
path, one of the two heat exchangers operates as a heat source
while the other one acts as a heat sink; the latter extracts heat
from its surroundings and transfers it to the former for
transmission to the ambient atmosphere. Thus, depending on the
direction of flow in the path containing the compressor, the
opposite portion of such a dual unit may serve to cool or to heat a
space bounded by the wall in which it is mounted; the bulkier and
frequently noisier compressor-equipped portion may then be located
externally of a building or room whose temperature is to be
controlled. Instead of a compressor, a Peltier-type electronic
current generator may be used to transfer heat from one fluid
stream to the other.
In the system disclosed in U.S. Pat. No. 3,696,634, heat transfer
between the two pump portions is effected by passing the primary
heat-carrying fluid through a coil within the hub structure and
letting the secondary heat-carrying fluid circulate about the coil.
Prior to assembly of the two portions into a rotary unit, through a
joinder of their respective hubs within the wall aperture, the
conduits on the side of the external heat exchanger must be sealed
to prevent the escape of primary fluid since the coil is located in
the hub of the internal heat exchanger; this can be carried out in
conventional manner with the aid of frangible diaphragms which are
pierced upon the establishment of the junctions between the coil
ends and the conduits. An object of our present invention is to
provide an improved system of this nature in which the need for
such temporary seals is obviated, with simplification of assembly
and with increased safety against leakage.
This object is realized, pursuant to our present invention, by
providing the two rotary heat exchangers with hollow hubs which,
after assembly, are coaxially coupled for joint rotation and
contact each other along a thermally conductive partition; the flow
paths for the primary and secondary fluids extend from respective
drum radiators, mounted on these hubs, to opposite sides of the
partition so that heat may pass from one fluid to the other
directly through that partition. In an advantageous embodiment, the
hubs have tubular wall portions of preferably frustoconical
configuration which are telescopically interfitted to provide an
extended area of contact; the thermal conductivity of the partition
constituted by these wall portions may be enhanced by coating at
least one contact surface with a layer of a relatively low-melting
metal or alloy which after assembly can be heated above its melting
point to fill any existing voids between the surfaces and to bond
the two hubs to each other by fusion.
The primary fluid may be a fluorochlorinated hydrocarbon, such as
Freon 22, as usually employed in air-conditioning equipment. The
secondary fluid, which generally will be in a partly liquid state,
should have a freezing point below the lowest operating temperature
and may be a low-boiling (e.g., methyl or ethyl) alcohol.
Advantageously, the conduit system of the primary flow path
includes one or more nozzles trained upon the thermally conductive
partition to distribute the expanding cooling fluid over a wide
area thereof if the system is operated as an air conditioner. The
nozzle may be the terminal of a capillary tube which bypasses the
compressor as it draws the liquified coolant from the periphery of
the corresponding drum radiator into the hub whence it is returned
to the compressor for recirculation to the radiator at an elevated
temperature. For room-heating operation, the compressor feeds the
nozzle with hot, compressed primary fluid which condenses inside
the hub, giving up its latent heat to the secondary fluid beyond
the partition, and is then drawn by the capillary to the radiator
for revaporization before returning to the compressor.
Another problem arising in the operation of such a unit, equipped
with a compressor, is the provision of simple means for driving
that compressor inside the hermetically sealed primary flow path of
one (usually the external) heat exchanger, itself rotatably mounted
in its wall-engaging support. The use of a sealed-in compressor
motor for this purpose is not convenient since it requires the
feeding thereof through mobile contacts such as slip rings. Thus, a
further object of our invention is to provide efficient means for
driving both the dual heat-exchange unit and the inaccessible
compressor with the aid of a single prime mover, such as an
electric motor, having a fixedly mounted stator or torque
generator.
The system of U.S. Pat. No. 3,696,321 comprises, as a common prime
mover for the heat-exchanger unit and the compressor, an electric
induction motor with a sealed-in stator and armature, the latter
being rigid with both the compressor rotor and a ring magnet inside
the hub structure coacting with a fixed annular magnet surrounding
that structure to generate eddy currents in a magnetically
permeable sleeve forming part of that structure whereby the same is
entrained at a speed lower than that of the compressor rotor to
create relative motion between that rotor and the compressor
housing secured to the hub. In accordance with a feature of our
present invention, only the motor armature is disposed inside the
sealed flow path of the primary fluid, being coupled with one of
the two relatively rotatable compressor sections (i.e., the
impeller) while the other compressor section (the housing) is
driven, together with the surrounding hub and radiator, by fluidic
entrainment, i.e., by the reaction torque generated in the
compressor itself. This reaction torque is proportional to the
degree of compression of the coolant vapors between the impeller
and the housing wall, the pressure in turn being a function of
vapor temperature. Such a fluidic coupling, therefore, has a
self-regulating effect in the case of an air-conditioning unit
since sluggish heat dissipation at the external radiator, due to
insufficient rotary speed, accelerates the rotation of the unit,
thereby increasing the throughput of ambient air until the drag
balances the increased reaction torque. The speed of the rotary
unit may also be controlled, if desired, by an eddy-current
generator aiding or opposing the fluidic entrainment; in the first
instance, such a generator may comprise a rotary magnet coupled
with the motor armature as in the system of the prior application,
whereas in the second instance it may include one or more
stationary magnets whose spacing from a coacting conductor is
preferably adjustable to vary the braking effect.
Such a fluidic coupling, though more fully described hereinafter in
conjunction with a dual heat pump of the specific type discussed
above, has also more general application in other thermogenic
devices such as, for example, steam engines with rotary boilers and
rotary condensers.
The secondary fluid may also be carried to or from the
corresponding radiator, in its liquid state, by capillary action;
thus, the internal heat exchanger may form a multiplicity of
narrow, generally radial channels extending, as in the system of
the copending application, between the radiator and the associated
hub. Instead of capillary tubing or channels, wicks may be used to
carry the liquid.
The above and other features of our invention will now be described
in detail with reference to the accompanying drawing in which:
FIGS. 1a and 1b, to be positioned side by side, show elevational
views (partly in section) of the two disassembled halves of a
two-circuit heat pump embodying our invention;
FIG. 2 is a perspective view showing the unit of FIGS. 1a and 1b
installed in a building wall; and
FIG. 3 is an enlarged axial sectional view of the region designated
III in FIG. 1a.
FIG. 1a, which illustrates the external portion A of a
heat-exchanger unit according to our invention, shows a mounting
plate 1 bearing upon the outside of a building wall E, e.g.,
underneath a window as seen in FIG. 2. Plate 1 has a peripheral
flange 2, serving as a mudguard, and a sleeve 49 provided with
bearings 50 for a central tubular shaft 3. This shaft supports a
spherically curved shell or cowl 4 of magnetically permeable
material enclosing, together with an end wall 5, a hermetically
sealed chamber 6 included in a closed path for the circulation of a
coolant such as Freon 22. Freely rotatable on horizontal shaft 3 is
another tubular shaft 7 supporting a squirrel-cage rotor 8 which
constitutes the armature of an induction motor having a laminated
stator 23 surrounded by field windings 25; stator 23 is fixedly
mounted on plate 1 and is externally supplied with alternating
(e.g., three-phase) current from a source not shown. Armature 8
comprises an array of short-circuited conductor bars which move
close to the inner surface of cowl 4 and follow its curvature.
A compressor in chamber 6 comprises two relatively rotatable
coaxial sections, i.e., an impeller 9 keyed to rotor shaft 7 and a
housing 10 integral with end wall 5. Housing 10 has an eccentric
inner peripheral surface brushed by a pair of diametrically
opposite impeller blades or vanes 51 which are radially movable in
section 9 and are maintained in contact with the housing surface by
centrifugal force as is well known per se. The periodically
expanding and contracting space between the vanes 51 (only one
shown) communicates intermittently with chamber 6 through an inlet
port 52 and with an outlet tube 18; though the inlet and the outlet
are shown in the same plane in FIG. 1a, they are of course
peripherally offset from each other. The reaction torque exerted by
the impeller 9 upon the housing 10 entrains the wall 5 along with
shaft 3 and cowl 4 in the direction of rotation of shaft 7 but at
considerably reduced rate compared with that of shaft 7; the latter
may turn, for example, at a speed of 2,900 RPM, with reference to
stator 23, upon energization of the windings 25.
End wall 5, covered by an end cap 11', is integral with a disk 11
which carries on its outer periphery a drum-type radiator
consisting of a multiplicity of horizontal tubes 13 which are
provided with annular or helical ribs 14, preferably of very thin
aluminum foil, in highly thermally conductive contact therewith. As
best seen in FIG. 3, tubes 13 are closed at their exposed ends and
open at their supported ends into an annular space 12 within the
disk 11. This space communicates with conduit 18 to receive
compressed cooling fluid therefrom. Another conduit 22, also
traversing the wall 5, leads from the bearing gap between shafts 3
and 7 to a peripheral channel 19 forming an enlarged extension of
space 12. Conduit 22 is a capillary tube serving to return
lubricating oil, driven centrifugally outwardly along with the
compressed vapors, to the chamber 6; tube 22 extends only far
enough into channel 19 to dip into an oil layer 47 floating on a
film of liquid coolant 46 condensed in radiator 13, 14 after giving
up its excess heat to the outer atmosphere, as illustrated at 45. A
further capillary tube 20 reaches into the film 46 to draw the
liquid into a hollow hub 16 of frustoconical configuration joined
in fluidtight fashion to the shaft 3 by means of a cup-shaped end
member 15; tube 20 passes through the bore of shaft 3 and through
an axial duct 17 in hub 16, terminating in one or more nozzles 21
trained upon the inner peripheral surface of the frustoconical hub
wall. Duct 17 has an opening 53, surrounding the nozzle 21 with
clearance, permitting the return of the expanded and vaporized
fluid to the shaft bore after it has cooled the frustoconical
surface 24 of the hub 16 which is made of highly thermally
conductive material. From the interior of shaft 3 the fluid returns
to chamber 6 through lateral apertures 54, 54' in shafts 3 and 7,
thereby completing the circuit.
The rotation of disk 11 causes ambient air to be axially aspirated
(arrow 26) and radially discharged (arrow 27) by centrifugal action
so as to sweep the surfaces of radiator 13, 14. with the compressed
vapors from conduit 18 (which may be duplicated at peripherally
spaced locations) heated to a temperature higher than ambient,
subunit A acts as a heat sink. If the connections of the conduits
are altered so that compressor 9, 10 delivers the hot fluid to
nozzle or nozzles 21 for condensation at the peripheral surface of
hub 16, with return of the condensate to channel 19 by capillary
action and recirculation of the vapors to chamber 6, this subunit
operates as a heat source.
The other half B of the rotatable unit, shown in FIG. 1b, comprises
a hollow hub 55 with a frustoconical sleeve 33 of highly
heat-conductive material fitting closely around the contact surface
24 of hub 16 when the two hub portions are coaxially nested within
an opening 37 of building wall E. Sleeve 33 advantageously consists
of elastically deformable material, such as a thin sheet of alloy
steel, and is shown internally coated with a layer 56 of
low-melting alloy or metal designed to promote heat transfer
between sleeves 33 and 16. Coating 56, when heated to a
sufficiently high temperature, flows over the surface 24 and bonds
the two hubs together after they have been mechanically
interconnected by bolts 57, 58 (FIG. 1a) and nuts 35, F (FIG. 1b).
Bolts 57 (only one shown), integral with mounting plate 1, pass
through bores 59 in a ring 34 which rests against a mounting plate
36 bearing upon the internal surface of housing wall E as part of a
fixed supporting structure D. Central bolt 58 is a solid extension
of the horizontal duct 17.
Subunit B further comprises a radiator drum consisting of finned
tubes 28, similar to those shown at 13, 14 in FIGS. 1a and 3, which
open at their supported ends 31 into an array of peripherally
spaced channels 29 in a disk 30 mounted on hub 55. These channels
are narrow enough to exert a capillary effect upon the liquid phase
of a secondary heat carrier, such as alcohol or Freon 11,
precipitating at 39 onto the frustoconical surface of sleeve 33
which is chilled by the vapors expanding along the opposite surface
of the partition 24, 33, 56 separating the primary and secondary
fluid circuits from each other. The secondary circuit includes a
tapering annular chamber 32 communicating with channels 30. The
condensate, assisted by centrifugal forces in its outward travel as
indicated by an arrow 40, is revaporized in tubes 28 and returns in
gaseous form to chamber 32. (When the unit is operated as a space
heater, capillary action draws the liquefied secondary fluid from
the tubes 28 into chamber 32 for volatilization along the sleeve 33
heated by the condensing primary fluid on the opposite side of the
partition.)
Subunit B is enclosed by a protective casing C having a filter
screen 38 and a corrugated peripheral wall 42 which may be
perforated with tiny holes to facilitate the circulation of ambient
air but which retains precipitated moisture inside the casing. This
moisture collects in an arcuate trough 43, hugging the lower
periphery of the rotary heat exchanger B over an arc of about
90.degree., and is swept up by a peripheral flange 44 of disc 30 to
the zenith of its orbit whence it is discharged from the casing by
a flexible drain pipe 48 extending along mounting plate 36 onto
which the casing C is fitted. Pipe 48, traversing the ring 34 and
the wall opening 37 as well as the opposite mounting plate 1, opens
onto a frustoconical recess of disk 11 which is provided with an
annular array of short transverse tubes 60 (only one shown) guiding
the accumulating water onto the ribs 14 of the external radiator
drum, thereby further assisting in the cooling of the primary
fluid.
The rotary speed of the unit A, B may be controlled by an
eddy-current brake illustrated as comprising an annular array of
permanent magnets 61 (only one shown) confronting the electrically
conductive annular flange 44 (FIG. 1b), these magnets being
threaded into the nonmagnetic plate 36 so that their distance from
flange 44 may be varied to adjust the braking effect.
The separation of two fluid circuits by a thermally conductive
partition 24, 33 may be also be utilized in a system wherein the
compressor 9, 10 is replaced by one or more Peltier-type current
generators or thermopiles inserted between the outgoing branch and
the return branch of the primary and/or the secondary flow path, or
between the two flow paths, to transfer heat substantially
adiabatically within a circuit or from one circuit to the
other.
* * * * *