Note: Descriptions are shown in the official language in which they were submitted.
9D-RA-14586
BACKGROUND OF THE INVENTION
The reverse air cycle tyEe of heat pump utilizes unidirection
refrigerant flow wherein the condenser and evaporator retain their
functions, but the air directed across them is redirected for different
operations. While -the heat pump is operating in the cooling mode,
outdoor air is passed in heat exchange relationship with the condenser
for liquifying the refrigerant and outside againi and indoor air is
passed in heat exchange relationship with the evaporator for cooling the
air circulated again. Conversely, in the heating mode, outdoor air
passes in heat exchange relationship with the evaporator for vaporizing
the refrigerant, then outside againi and indoor air is passed in heat
exchange relationship with the evaporator for vaporizing the refrig-
erant, then outside again; and indoor air is passed in heat exchange
relationship with the condenser for heating the air and circulated
again.
In U.S. Patent No. 2,878,657-Atchison, assigned to General
Electric Company, the assignee of the present invention, discloses a
heat pump wherein the air conditioning unit includes a plurality of air
controlling valves each of which is associated with an opposed inlet and
outlet opening of the unit that permit selective control of the air
flowing into and discharging from the unit in order to direct air either
from the outside or from within the enclosure over either of the heat
exchangers disposed within separate compartments of the unit.
Under certain operating conditions in the heating cycle,
evaporator may operate at such low outdoor ambient temperatures as to
cause the accumulation of a coating or layer of frost on its surface.
Since frost when it accumulates operates as a barrier to heat transfer
between the evaporator and the air being circulated thereover, the
efficiency of the unit is markedly reduced. Further, unless means are
provided for interrupting the accumulation of frost, the evaporator can
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9D-RA-14586
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become complete]y filled with a layer of frost that may effectively
block air passage therethrough. This blockage of air results in the
loss of heat exchange and if allowed to continue can cause refrigeration
system components to fail and can also result in compressor burn-out
unless compressor operation is terminated.
The shutting down of compressor operation each time frost
accumulates severely curtails the operation of the unit in the heating
cycle and accordingly the efficiency of the unit as a heating means at
temperatures below the evaporator frosting level.
In U.S. Pat. No. 3,555,842-Bodcher, a defrost line connects
the upper inlet of the condenser to the upper inlet of the evaporator
and includes a defrost valve which is closed during operation of the
compressor but opens when compressor operation terminates. A return
line connects the evaporator collector with the lower part of the
condenser and includes a valve which operates in the same manner as the
defrost valve.
In U.S. Pat. 4,158,950-~cCarty, assigned to the General Electric
Company, assignee of the present invention, there is disclosed a defrost
arrangement for refrigeration system of the reverse cycle. A secondary
defrost circuit is provided which permits refrigerant flow to by-pass
the compressor when compressor operation terminates.
SUMMARY OF T~E INVENTION
The present invention provides an air conditioning apparatus
for conditioning air in an enclosure having a wall opening, and more
particularly to an air conditioner including a housing adapted to be
positioned in the wall opening with one side of said housing facing the
outdoors and the opposite side of the housing facing said enclosure. A
central chamber is defined by spaced partitions dividing the housing
into an evaporator compartment and a condenser compartment.
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9D-RA-14586-McCarty
A refrigerator system of the type having a refrigerant capable
of boiling under relatively low pressure to absorb heat and condensing
under relatively high pressure to expel heat, a compressor for com-
pressing a refrigerant fluid in gaseous phase having a high pressure
outlet port and a low pressure inlet port, a condenser in said condenser
compartment having a high pressure inlet port and a high pressure liquid
refrigerant outlet port, means connecting said inlet port to said com-
pressor outlet, an evaporator in said evaporator compartment having a
low pressure liquid inlet port in fluid communication with said high
pressure liquid refrigerant outlet port of said condenser by a fluid
line, and having a low pressure outlet port at its upper portion, means
connecting said outlet port with said inlet port of said compressor, and
a flow control means in said fluid line.
Positioned in each of the compartments is a fan shroud that
substantially divides the evaporator and condenser compartments into
inlet and outlet sections, each of the sections having an opening in
both the indoor and outdoor facing side of the housing. A fan is
positioned in each of the shrouds for circulating air through the
evaporator and condenser compartments in a direction from the inlet
section to the outlet section. Movable air valve means are provided for
controlling the flow of air through the evaporator and condenser com-
partments for heating or cooling the enclosure. The air valve means
include a first damper slidably arranged in the indoor facing side of
the housing that is associated with the indoor facing openings of the
compartments and a second damper slidably arranged in the outdoor facing
side of the housing that is associated with the outdoor facing opening
of the compartments. The dampers are selectively positioned to a first
cooling position wherein the indoor facing openings of the evaporator
compartment communicate with the enclosure and the outdoor facing
openings of the condenser compartment communicate with the outdoors for
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cooling the enclosure air, and to a second heating position wherein the
indoor facing openings in the condenser compartment communicate with the
enclosure for heating the air.
The refrigerator system includes defrost means including a
first defrost flow passage connected between the low pressure outlet
port of the evaporator and the high pressure inlet of said condenser,
and a second defrost flow passage connected between the high pressure
outlet of the condenser and the low pressure inlet of said evaporator,
each of the defrost flow passages are provided with a valve.
The valve means are operable for holding the valves in their
closed position when a refrigerant pressure differential is present in
the system and being operable to an open position when the pressure
differential is bled down through the flow control means after the
compressor operation terminates, so that a non-restrictive refrigerant
defrost flow path circuit is established through the first defrost flow
passage between the upper portions of the condenser and evaporator and
through the second defrost flow passage between the lower portior of
condenser and evaporator, thereby allowing liquid refrigerant when
present in the lower portion of the evaporator to flow through the
second defrost flow passage into the lower portion of the condenser,
while the warmer gaseous refrigerant when present in the condenser will
flow through the first defrost flow passage into the upper portion of
the evaporator to raise the temperature of the evaporator and melt frost
when present.
DESCRIPTION OF THE DRAWIN6S~
Figure l is a side elevational view in section of the
self-contained air conditioning unit incorporating the present invention;
Figure 2 is a front elevational view partially in section of
the self-contained air conditioning unit incorporating the present
invention;
Figure 3 is a schematic view of the refrigeration system
according to this invention~
9D-R~-14586
~7~75
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings and more particularly to Figure
1, there is shown an air conditioner unit 10 including a housing 12 that
is adapted to be arranged in an opening 14 in the wall 16 of an enclosure
to be conditioned. The housing 12 is generally rectangular in shape
tFigure 2) and includes bottom and top walls 18 and 20 respectively
interconnected by longer side walls 22 and 24. The housing walls
(Figure 1) define generally a front opening 26 disposed in the enclosure
side of wall 16 and a rear opening 28 disposed in the outdoor side of
wall 16. Arranged over the front opening 26 of housing 12 is a front
grille or appearance member 25 which includes appropriate air deflecting
vanes 27, while a grille 29 is positioned over the rear opening 28.
Mounted within the housing 12 is a removably arranged chassis
30 on which is mounted an air conditioner regrigeration
system including an evaporator 32 and a condenser 34 connected in
refrigerant flow relationship with a compressor 36. Referring to
Figures 1-2, it will be seen that the chassis 30 includes a plurality of
parallel spaced partitions that divide the housing 12 in a manner to be
explained hereinafter to include a central or machine compartment 38,
which houses the compressor 36 and a control box 39, an upper or
evaporator compartment 40 and a lower or condenser compartment 42. The
partitions of chassis 30 include two spaced substantially parallel
central partitions 44 and 46 which define the central compartment 38.
And upper fan shroud partition member 48 substantially divides the upper
evaporator compartment 40 into an inlet area 50 defined by member 48 and
partition 46 and an outlet area 52 defined by member 48 and the upper
wall 20 of housing 12. The evaporator 32 is securely held between the
partitions 46 and 48 in the inlet area 50. A lower fan shroud partition
54 substantially divides the lower condenser compartment 42 into an
outlet area 56 defined by the member 54 and partition 44 and an inlet
9D-RD-14586
975
area 58 defined by member 54 and sump pan 60 arranged in the lower wall
18 of housing 12. The condenser 34 is securely held between the parti-
tions 44 and 54 in the inlet area 58. The partitions are supported in
their spaced relationship by a plurality of support members or rods 62.
Air is circulated by a fan 72 arranged in shroud 48 from the
evaporator inlet section 50 to evaporator outlet section 52 and similarly
air is circulated by a fan 73 arranged in shroud 54 from the condenser
inlet 58 to condenser outlet section 56. Fan 72 is mounted on the shaft
74 of a motor 76 while fan 73 is mounted on the shaft 78 of a motor 80.
Referring to Figure 1, it can be seen that the inlet and
outlet sections of the evaporator and eondenser compartments are arranged
within the rectangular housing 12 with each section having a pair of
openings therein, one communicating with opening 28 facing the outdoors,
and a second opening communicating with opening 26 facing the enclosure
whereby air can be both introduced and discharged from the evaporator
and condenser compartments in two different directions. More specifically,
the evaporator compartment inlet section 50 contains openings 100 and
102 and the outlet section 52 contains openings 104 and 106 in the
indoor and outdoor side respectively of housing 12. Similarly condesner
compartment inlet section 58 is provided with openings 108 and 110, and
the outlet section 56 is provided with opening 112 and 114 in the indoor
and outdoor side respectively of housing 12. As will be hereinafter
explained, the inlet and outlet openings of each compartment on the
indoor and outdoor side of housing 12 is provided with means for selec-
tively controlling the air flow through the condenser and evaporator
compartments.
It should be noted that the evaporator 32 and the condenser 34
are of the spine fin type consisting of one continuous tube member wound
spirally so that each heat exchanger is arranged in circular fashion
within their respective compartment inlet sections. This configuration
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9D-RA-14586
~7~75
is desirable because the inlet openings 100, 102 and 108, 110 leading to
their respective sections 50 and 58 are arranged opposite sides thereof
and accordingly, the air flows into the sections from opposite directions.
That is, by this heat exchanger configuration, it is possible to more
efficiently take advantage of all of the space within each of the inlet
sections and to utilize the capacity of the heat exchangers to their
fullest extent regardless of the direction of air flow.
As may be seen in Figure 1, the front openings 26 and 28 of
housing 12 are provided with channel or track portions 116 that extend
completely around the openings. Each opening 26 and 28 is provided with
means for controlling air flow through the evaporator and condenser
compartments. In the present embodiment, air flow is controlled by a
pair of air valves or dampers 118 and 120 that are fitted for vertical
movement in the track portions 116 on the openings 26 and 28 respec-
tively.
In the illustrated embodiment of the invention, the dampers
are interconnected to insure proper location of one damper over a com-
partment inlet and outlet opening one side of the housing by movement of
the other damper arranged on the other side of the housing. To this end
(Figure 2), there is provided a first set of four rollers 124 rotatably
mounted on the side wall 24 of housing 12 and a similar set of four
rollers 126 rotatably mounted on the side wall 22 of housing 12. With
reference to Figure 1, it will be seen that the rollers are mounted near
the corner portions of the side walls to, in effect, outline a rectangle
on each side wall. Arranged on rollers 124 is an endless cable 128,
while an endless cable 130 is arranged on the rollers 126. The front
damper 118 is secured to each vertical pass of the cables 12B, 130 at a
point where they communicate with the front opening 26, while the back
damper 120 is secured to the cables 128, 130 at a point where they
communicate with the rear opening 28. To this end, the dampers are
provided with fastening portions 132 located on the vertical edges
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9D-RA-14586
7~7S
thereof that is crimped to the cables. Accordingly~ vertical movement
of the front damper 118 positioned in the enclosure side of housing 12
by the user of the air conditioner will cause an opposite vertical
movement of the back damper 120 positioned in the outdoor side of the
housing 12.
In use with the dampers 118, 120 arranged in the heating
position shown in Figure 1, the air flow through the conditioner 10 is
such as to heat the air circulated from the enclosure. That is in the
heating mode with the damper 118 closing the enclosure side inlet
opening 100 and outlet opening 104 of evaporator compartment 40, air
from the enclosure is drawn into the condenser compartment 42 through
inlet 108 where it is passed through the condenser 34 heated and then
back into the enclosure through outlet 112. In the heating mode, damper
120 closes the outside inlet openings 110 and outlet opening 114 of the
condenser compartment 42 and air from the outdoors is drawn into the
evaporator compartment through inlet 102 where it is passed through the
evaporator 32 and back into the outdoors through outlet 106.
In the cooling mode, the indoor damper 118 would be positioned
by the user of the air conditioner over the enclosure side condenser
inlet 108 and outlet 112 section openings so that enclosure air is drawn
into the evaporator compartment through uncovered inlet 100 where it is
passed through the evaporator and cooled and then back into the
enclosure through outlet 104. In this mode the outdoor damper 120 would
be positioned over the outdoor evaporator inlet 102 and outlet 106
openings so that outdoor air is drawn into the uncovered condenser
compartment 42 through inlet 110 where it is passed through the
condenser and then back into the outdoors through outlet 114. To
facilitate movement of the indoor damper 118 by the user, there is
provided a pair of handles 115, one on each vertical edge.
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9D-RA-14586-McCarty
Control means are provided that prevent operation of the unit
in the event the damper doors or air valves are not positioned properly
relative to the selected inlet and outlet openings. To this end, there
is mounted in the control box 39 a pair of switches 136 and 138. The
switch 138 is a heater control switch through which a resistance heater
140 is energized. The switch 138 is moved to its closed position when
the damper 118 is in its up position (as shown) and enclosure air is
accordingly circulating through the condenser compartment 42. The
switch 138 also orients the thermostat 142 so that it functions during
l the heating cycle between a lower ambient and a higher set temperature.
The switch 136 is effective when the damper is in its down or cooling
position and enclosure air is accordingly circulating through the
evaporator compartment 40. The switch 138 orients the thermostat 142 so
that it functions during the cooling cycle between a higher ambient and
lower set temperature. Another féature of the switch arrangement is to
prevent operation of the air conditioner if both switches are closed.
In effect, the switches are so arranged that the damper 118 must be
either in its fully up heating position which means damper 120 is in its
fully lowered position or in its down position, or cooling position
which means damper 120 is in its fully up position.
In the course of this unit operating in the heating mode,
water vapor under certain ambient conditions condenses on the evaporator
through which as explained hereinbefore outdoor air passes. In some
instances, the amount of water vapor available in the outdoor ambient is
great enough to solidify and form a layer of ice which blocks air flow
through the heat exchcnger. This layer of ice must be removed when it
has a thickness which opposes the desirable transfer of heat from the
heat exchanger. Accordingly, by the present invention, means are
provided that perm~t defrosting and elimination of frost when present in
the evaporator each time operator of the system compressor terminates.
9D-RA-14586
S
In its preferred application, the present embodiment of the defrost
system is intended to be used in defrosting the evaporator in a manner
that will not completely interrupt the heating process of the enclosure
air.
The means for effecting the defrosting of the evaporator as
shown in Figure 3 of the drawing includes a by-pass line or conduit 29
which is connected between the lower portions of evaporator 32 and
condenser 34. In effect, the by-pass 29 is arranged in parallel flow
relationship with the system expansion device 27 in the system liquid
line 25. A second by-pass line or conduit 31 connected between the
upper portion of -~he evaporator 32 or adjacent suction line 33 and the
upper portion of the condenser 34 or adjacent the discharge line 35. In
effect, a circuit through line 31 will by-pass the compressor 36. The
defrost circuit provided by the present invention is through a closed
loop provided by conduits 29, 31 and heat exchangers 32 and 34 with the
compressor 36 and expansion device being by-passed. Means are provided
to prevent refrigerant flow through either conduit 29 or 31 when the
compressor 36 is circulating refrigerant during normal operation of the
refrigerating system. To this end, valves 37 and 39 are provided
respectively in the conduits 29 and 31.
The valves 37 and 39 are designed to close when a pressure
differential is present in the system. Since this pressure differential
is created by compressor operation, valves 37 and 39 will remain closed
when the system is operating. Accordingly, the added by-pass conduits
29 and 31 and their respective valves 37 and 39 have no effect on the
system during its normal operation. Further, the valves are designed to
remain closed until after the compressor operation terminates and the
system pressure differential created by the operating compressor is fed
or bled down through the normal system expansion device 27. At this
point, the valves 37 and 39 will open and the by-pass defrost circuit
mentioned above is established.
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9D-RA-14586
~'7975
In operation with the unit in the heating mode and a frost
condition sensed on the evaporator 32 compressor operation will termi-
nate. At this time, as mentioned above, with the compressor 36 not
operating the system pressure differential will bleed down through the
system expansion device 27. Accordinglyr the valves 37 and 39 being no
longer under the influence of the pumped refrigerant flow will move to a
neutral or open position and a non-restricted defrost flow path through
conduit 29 and 31 between the lower and upper portions of the heat
exchangers is established. Hot gaseous phase refrigerant will flow from
the upper portion of the condenser 34 through conduit 31 and into the
upper portion of the frosted evaporator 32. The liquid refrigerant in
the lower portion of the evaporator 32, which is relatively cool, flows
through line 29 into the lower portion of the warmer condenser 34 when
it is heated and returns to gaseous phase.
The liquid refrigerant accumulated in the frost evaporator 32
will drain into the condenser 34 containing gas due to a gravity head
created by the accumulated liquid height and the location of the evapor-
ator above the condenser. The cold liquid at approximately 32F in the
evaporator will absorb heat from the warm condenser and will change to
gas. As liquid drains from the bottom of the evaporator, warm gas will
enter the top through conduit 31. This flow of cold liquid out of the
bottom of evaporator through conduit 29 to the warm condenser and the
flow of warm gas out of the top of the condenser through conduit 31 to
the cold evaporator produces an effective defrosting cycle that will
continue until the temperature of the evaporator temperature approaches
the temperature of the condenser. At this point, gravity flow will
terminate because liquid can accumulate in both heat exchangers.
Heat added to the refrigerant during the defrosting comes from
the warm condenser which is in a relatively warm ambient in the heating
rnode. By the present invention, the auxiliary heater 140 together with
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9D-RA-14586-McCarty
fan 73 can be employed to provide warm air flow through the condenser
34. While the heater 140 and fan 73 ~ay be energized to provide auxi-
liary heat during peak demands, it also provides heat to the enclosure
during the defrosting operation. ~he heater function during the defrosting
or compressor-off period is ef~eotive in maintaining the temperature of
the condenser 34 equal to or above t~e enclosure ambient and, in fact,
elevated enough to ensure that the 3~ liquid refrigerant entering the
bottom portion of the condenser is reburned to the evaporator through
line 31 in gaseous phase.
In summary, the circulation çf relatively warm refrigerant in
gaseous phase from the condenser 34 into the relatively cold frost-laden
evaporator 32 and the simultaneous extraction of the colder refrigerant
in liquid phase from the lower portion of the evaporator produces a heat
transfer which provides for evaporator defrosting. This free flowing
lS circulation of refrigerant past the system expansion device and com-
pressor continues until the pressure an~d temperature in the system
equalize.
It should be apparent to those skilled in the art that the
embodiment described heretofore is ~onsidered to be presently preferred
form of this invention. In accordan~e with the Patent Statutes, changes
may be made in the disclosed apparatus and the manner in which it is
used without actually departing fr~ the true spirit and scope of this
invention.
