SOLAR AUGMENTED HEAT PUMP SYSTEM WITH AUTOMATIC STAGING RECIPROCATING COMPRESSOR

THERMOPOMPE A COMPRESSEUR ALTERNATIF A REPRISE EN CHARGE AUTOMATIQUE ASSISTEE D'UN HELIOCAPTEUR

English Abstract

ABSTRACT
A multi-cylinder reciprocating compressor is
automatically staged at low ambient temperature to improve
refrigerant volume flow while facilitating subcooler operation
and return of vaporized refrigerant from the subcooler to the
inlet of the second stage cylinders of the compressor in the
two stage mode. A solar evaporator substitutes for the
outdoor coil when the solar heated storage tank temperature
exceeds that of ambient. During staging mode, the wrist pins
of the low side cylinders and the high side cylinder undergo
proper load reversals, since intermediate suction pressure
is applied to the wrist pin of the high side cylinders.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. An air source heat pump system comprising:
a first indoor heat exchange coil 12,
a second outdoor heat exchange coil 14,
a multi-cylinder reciprocating compressor 10,
first conduit means carrying refrigerant,
said first conduit means including a reversing valve 24 and
connecting said coils 12, 14 and said compressor 10 in a
primary closed series loop, said reversing valve 24
functioning to cause said indoor 12 and outdoor 14 coils to
operate alternately as evaporator and condenser,
Characterized by:
a third heat exchange coil 16,
said first conduit means further
including means for connecting said third heat exchange
coil 16 across said outdoor coil 14,
first control valve means 107, 108 within
said conduit means for selectively controlling refrigerant
flow through said primary closed loop to said second 14 and
third 16 heat exchange coils,
solar energy heat supply means 18, 120
for supplying thermal energy to said third heat exchange
coil 16,
means 136 for sensing the temperature of
the ambient air passing over said outdoor coil 14, and
control means 126 for operating said
first control valve means 107-108 in response to said
temperature sensing means;
whereby, thermal energy input to said
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heat pump system during heating mode may be supplied
selectively by said second heat exchange coil acting as an
air source evaporator or said third heat exchanger coil via
said solar energy supply means.
2. The heat pump system as claimed in claim 1,
wherein said solar energy heat supply means comprises a
storage tank 18, a heat sink fluid 22 being within said
storage tank, means for selectively circulating said stored
heat sink fluid to said third heat exchange coil 16 for
thermal absorption by the primary loop refrigerant with
said third heat exchange coil 16 acting as solar evaporator,
and means 20, 116 for supplying solar energy supplied heat
to said storage tank 18 for heating said heat sink fluid 22
to increase the temperature of the same.
3. The heat pump system as claimed in claim 2,
wherein said solar energy heat supply means for heating of
said heat sink fluid comprises a solar collector 20, a fourth
heat exchange coil 118 within said storage tank, and in
thermal contact with said heat sink fluid 22, and second
conduit means 116 for connecting said storage tank 22 and
carrying a circulating heat exchange fluid therein such that
solar energy impinging on said collector 20 is transmitted to
said storage tank coil 118 for heating said heat sink fluid 22.
4. The heat pump system as claimed in claim 2,
wherein said heat sink fluid 22 comprises glycol and said
means for circulating said glycol between said storage tank
and said third heat exchange coil 16 comprises third conduit
means 120 for communicating said storage tank 18 to said
third heat exchange coil 16, a solenoid operated control valve
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124 within said third conduit means 120 and pump means 122
within said third conduit means 120 and intermediate of said
storage tank 18 and said third heat exchange coil 16 for
circulating said glycol therebetween.
5. The heat pump system as claimed in claim 3,
wherein said heat sink fluid 22 comprises glycol and said
means for circulating said glycol between said storage tank
18 and said third heat exchange coil 16 comprises third
conduit means 120 for communicating said storage tank 18 to
said third heat exchange coil 16, a solenoid operated control
valve 124 within said third conduit means 120 and pump means
122 within said third conduit means 120 and intermediate of
said storage tank 18 and said third heat exchange coil 16 for
circulating said glycol therebetween.
6. The heat pump system as claimed in claim 1,
wherein said reciprocating compressor comprises a plurality
of cylinders 34, 36, 42, 44, and said system control means
comprises means 126, 86 responsive to said ambient air
temperature sensing means 136 for automatically staging said
compressor cylinders at low ambient temperature to increase
refrigerant flow rate through said compressor.
7. The heat pump system as claimed in claim 4,
wherein said reciprocating compressor comprises a plurality
of cylinders, 34, 36, 42, 44, and said system control means
comprises means 126, 86 responsive to said ambient air
temperature sensing means 136 for automatically staging said
compressor cylinders at low ambient temperature to increase
refrigerant flow rate through said compressor.
8, The heat pump system as claimed in claim 5,
wherein said reciprocating compressor comprises a plurality of
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cylinders, 34, 36, 42, 44, and said system control means
comprises means 126, 86 responsive to said ambient air
temperature sensing means 136 for automatically staging said
compressor cylinders at low ambient temperature to increase
refrigerant flow rate through said compressor.
9. The heat pump system as claimed in claim 6,
wherein said compressor 10 comprises a first 26 and a second
28 cylinder head, each cylinder head comprising two cylinders
34, 36-42, 44 said first cylinder head 26 including first
manifold means 23, 25 separating said cylinders 34, 36 and
defining low 30, 31 and high 32, 33 pressure sides for
respective cylinders 34, 36 said second cylinder head 28
comprising second manifold means 45 defining commonly, low 40
and high 38 pressure sides for both cylinders 42, 44 said
first cylinder head 26 including a first inlet 46 to the low
pressure side 30 of one cylinder 34 and a second inlet 48 to
the low pressure side 31 of the other cylinder 36, and said
second cylinder head 28 comprising a third inlet 52 common
to the low pressure 40 side of both cylinders 42, 44, said
first cylinder head 26 comprising first and second outlets
58, 56 respectively for the individual cylinders, said second
cylinder head 23 comprising a third outlet 54 common to both
cylinders 42, 44, a fourth inlet 50 for the other 36 of the
cylinders of said first cylinder head 26 and wherein said
first conduit means comprising means defining an outlet
manifold 72 connected to the outlet 5,8 of said first cylinder
head cylinder 34 having a single inlet 46, and to the
outlet 54 of said second cylinder head common to both
cylinders, conduit means 74 for connecting said outlet
manifold 72 to said reversing valve 24 and parallel with the
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outlet 56 of said first cylinder head cylinder 36 having dual
low side inlets, means for connecting said outlet manifold 72
to said fourth inlet 50 for said other cylinder 36 of said
first cylinder head 26, second control valve means 86 within
said conduit means 84 connecting said outlet manifold to said
fourth inlet 50 of said other 36 cylinder of said first
cylinder head 26, a first check valve 76 within said conduit
74 leading from said outlet manifold 72 to said reversing
valve 24 to permit direct flow from said outlet manifold
to said reversing valve but not vice versa and a second check
valve 88 within said conduit means 70 leading from said
reversing valve 24 to said second inlet 48 to said other
cylinder 36 of said first cylinder head 26 to permit direct
flow from said reversing valve to said second inlet but not
vice versa, such that upon energization of said second control
valve means 86, said one 34 cylinder of said first cylinder
head and both cylinders 42, 44 of said second cylinder head
28 operate in first stage compression and said other cylinder
36 of said first cylinder head 26 operates in second stage
with said first check valve 76 isolating said compressor first
and second stages.
10. The heat pump system as claimed in claim 7,
wherein said compressor 10 comprises a first 26 and a second
28 cylinder head, each cylinder head comprising two cylinders
34, 36-42, 44 said first cylinder head 26 including first
manifold means 23, 25 separating said cylinders 34, 36 and
defining low 30, 31 and high 32, 33 pressure sides for respective
cylinders 34, 36 said second cylinder head 28 comprising second
manifold means 45 defining commonly, low 40 and high 38
pressure sides for both cylinders 42, 44 said first cylinder
head 26 including a first inlet 46 to the low pressure side
30 of one cylinder 34 and a second inlet 48 to the low pressure
side 31 of the other cylinder 36, and said second cylinder head
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28 comprising a third inlet 52 common to the low pressure 40
side of both cylinders 42, 44 said first cylinder head 26
comprising first and second outlets 58, 56 respectively for
the individual cylinders, said second cylinder head 28
comprising a third outlet 54 common to both cylinders 42, 44,
a fourth inlet 50 for the other 36 of the cylinders of said
first cylinder head 26 and wherein said first conduit means
comprising means defining an outlet manifold 72 connected to
the outlet 58 of said first cylinder head cylinder 34 having
a single inlet 46, and to the outlet 54 of said second cylinder
head common to both cylinders, conduit means 74 for connecting
said outlet manifold 72 to said reversing valve 24 and parallel
with the outlet 56 of said first cylinder head cylinder 36
having dual low side inlets, means for connecting said outlet
manifold 72 to said fourth inlet 50 for said other cylinder 36
of said cylinder head 26, second control valve means 86 within
said conduit means 84 connecting said outlet manifold to said
fourth inlet 50 of said other 36 cylinder of said first cylinder
head 26, a first cheek valve 76 within said conduit 74 leading
from said outlet manifold 72 to said reversing valve 24 to
permit direct flow from said outlet manifold to said reversing
valve but not vice versa and a second check valve 88 within
said conduit means 70 leading from said reversing valve 24
to said second inlet 48 to said other cylinder 36 of said
first cylinder head 26 to permit direct flow from said reversing
valve to said second inlet but not vice versa, such that upon
energization of said second control valve means 86, said one
34 cylinder of said first cylinder head and both cylinders
42, 44 of said second cylinder head 28 operate in first
stage compression and said other cylinder 36 of said first
cylinder head 26 operates in second stage with said first
check valve 76 isolating said compressor first and second stages.
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11. The heat pump system as claimed in claim 9,
wherein said system further comprises a subcooler 21 operatively
connected within said first conduit means between said indoor
and outdoor coils and said subcooler includes a return line
connecting to said first conduit means between said outlet
manifold 72 and said fourth inlet 50 for said other cylinder
36 of said first cylinder head 26 downstream of said second
control valve means 86 such that during multi-stage compression
the refrigerant vapor from said subcooler 21 at intermediate
pressure is directed commonly with the first stage discharge
to the fourth inlet 50 at the low side of said other cylinder
36 constituting the second stage of said reciprocating compressor.
12. The heat pump system as claimed in claim 10,
wherein said system further comprises a subcooler 21 operatively
connected within said first conduit means between said indoor
and outdoor coils and said subcooler includes a return line
connecting to said first conduit means between said outlet
manifold 72 and said fourth inlet 50 for said other cylinder 36
of said first cylinder head 26 downstream of said second control
valve means 86 such that during multi-stage compression the
refrigerant vapor from said subcooler 21 at intermediate pressure
is directed commonly with the first stage discharge to the
fourth inlet 50 at the low side of said other cylinder 36
constituting the second stage of said reciprocating compressor.
13. A refrigeration system comprising:
a first heat exchange coil 12,
a second heat exchange coil 14,
a multi-cylinder reciprocating compressor 10,
first conduit means carrying refrigerant for
connecting said coils and said compressor in a closed series
refrigeration loop,
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the improvement wherein:
said compressor 10 comprises a first 26 and a second
28 cylinder head, each cylinder head 26, 28 comprising two
cylinders, said first cylinder head 26 including first
means 23, 25 separating said cylinders 34, 36 and defining low
pressure 30, 31 and high pressure 32, 33 sides for respective
cylinders, said second cylinder head 28 comprising second
manifold means 48 defining commonly, low 40 and high 38 pressure
sides for both cylinders, said first cylinder head 26 including
a first inlet 46 to the low pressure side 30 of one cylinder
34 and a second inlet 48 to the low pressure side 31 of the
other cylinder 36, said second cylinder head 28 comprising a third
inlet 52, common to the low pressure side 40 of both cylinders
42, 44, said first cylinder head 26 comprising first 58 and
second 56 outlets, respectively, for the individual cylinders,
said second cylinder head 28 comprising a third outlet 54 common
to both cylinders 42, 44 a fourth inlet 50 for the other cylinder
36 of said first cylinder head 26,
said first conduit means comprising means defining an
outlet manifold 72 connected to the outlet 58 of said first
cylinder head cylinder 34 having a single inlet and to the
outlet 54 of the second cylinder head common to both cylinders,
said first conduit means including means 74 for connecting said
outlet manifold 72 in parallel with the outlet 56 of the first
cylinder head cylinder 36 having the dual low side inlets to
said first heat exchange coil 12,
conduit means for connecting said outlet manifold 72
to said fourth inlet 50 for said other cylinder 36 of said
first cylinder head 26,
a control valve 86 within said conduit means 84
connecting said outlet manifold to said fourth inlet 50 of said
other cylinder 36 of said first cylinder head 26,
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a first check valve 76 within said conduit means 74
leading from said outlet manifold 72 to said first. coil 12
for permitting direct flow from said outlet manifold to said
first coil but not vice versa, and
a second check valve 88 within said conduit means 70
leading to said second inlet 48 to said other cylinder 36 of
said first cylinder head 26 for permitting direct flow from said
second coil to said second inlet but not vice versa,
said system further comprising a subcooler 21 operatively
connected between said first coil 12 and said second coil 14
and including a return line from said subcooler 21 to said first
conduit means between said outlet manifold 72 and said fourth
inlet 50 for said other cylinder 36 of said first cylinder head
26 downstream of said control valve 86 such that, by operation
of said control valve 86 and check valves 76 and 88, during
multi-stage compression, the refrigerant vapor from the subcooler
21 at intermediate pressure is directed commonly with the first
stage discharge from said discharge manifold 72 to said fourth
inlet 50 at the low side of said other cylinder 36 constituting
the second stage of said reciprocating compressor.
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Description

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~07~s68
SOLAR AUGMEMTED HEAT PUMP SYSTEM
WITH AUTOMATIC STAGING RECIPROCATING COMPRESSOR
This invention relates to air source heat pumps,
and more particularly to solar augmented air source heat
pump systems employing a multi-cylinder reciprocating
compressor.
A reciprocating compressor has long been employed
to compress refrigerant vapor in an air source heat pump
system with the compressor in series with and between the
outdoor and lndoor coils which coils trade functions; the
outdoor coil constituting the air source evaporator under
heating mode and the indoor coil, the condenser; while
during cooling mode the indoor coil becomes the system
evaporator and the outdoor coil becomes the air source
condenser. When the heat pump is operating under heating
mode, the system compression ratio increases as the air ,~
source heat pump system operates under colder and colder
ambient. For instance, assuming that the reciprocating
compressor comprises four cylinders and assuming 100%
volumetric efficiency under single stage operation would -
equal four flow units, at 50~ volumetric efficiency the -~
single stage operation results is equivalent to two flow
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units. In higher system compression ratios, the
reciprocating compres~or volumetric efficiency drops to very
low value and 25~ volumetric efficiency under max heating '
conditions are common. For a single stage four cylinder
operation, the result is one flow unit ,at the higher
compressor ratios.
Further, it is conventional to improve system
efficiency by incorporating a subcooler between the :indoor
and outdoor coils which functions to subcool the liquid
refrigerant aownstream of the coil constituting the
condenser and prior to feeding the same to the coil acting
as an evaporator of the system. A portion of the high
pressure liquid refrigerant is bled from the system and
vaporized to further reduce the temperature of that portion
of the refrigerant delivered to the coil functioning as the
evaporator for the system under that particular modeO The
vapor generated in the subcooler is at a pressure which is
well above the suction pressure to the reciprocating
compressor. The expansion of that refrigerant to the
pressure of the refrigerant vapor passing from the
downstream side of the coil functioning as the evaporator in
the system and entering the inlet or suction side of the
compressor, constitutes a system-loss reducing the
efficiency of the heat pump system.
Solar collectors have been employed as a source of
thermal energy to supplement thermal energy input to
refrigeration systems, particularly heat pumps.
The invention is directed to an air source heat
pump system of the type including a first heat exchanger
forming an indoor coil, a second heat exchanger forming an
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outdoor coil, and a multi-cylinder reciprocating compressor.
Conduit means carrying refrigerant includes a reversing -
valve which connects -the first and second heat exchangers
and the compressor in a closed series primary re~rigeration
loop to permit the outdoor and indoor coils to operate
alternatively as the evaporator and condenser for the system,
depending upon heating or cooling mode. The improvement
comprises a third heat exchanger with -the conduit means
connecting the third heat exchanger across the outdoor coil.
Selectively operable valve means within said conduit means
causes refrigerant to flow through said third heat
exchanger while isolating the outdoor coil from the closed
primary loop. A storage tank containing a mass of heat sink
fluid is connected in a secondary closed loop including
the third heat exchanger, and a solar collector is
operatively connected to the storage tank for normally
supplying heat to the heat sink fluid. Means are provided
for sensing the temperature of the ambient air passing over
~he outdoor coil and the temperature of the stored heat
sink fluid, and means are provided for comparing said
temperatures and for operating said selectively operable
control valve means.
The heat sink fluid of the storage tank may
comprise glycol or other fluids, and the system may be
pro~ided with a pump and solenoid valve means within the
closed loop conne~ting the storage tank to the solar assist
e~aporator coil for controlling circulation of the glycol
therebetween.
Preferably, the reciprocating compressor comprises
a plurality o~ cylinders and the system further comprises

~.076)9G8
means for automatically controlling primary loop reErigerant
circulation to and from the compressor for operating the
compressor in single stage with all cylinders in parallel
or for placing, in response to ambient temperature drop
below a predetermined value under system heating mode, at
least one cylinder under high side multi-stage compressor
operation. The system may further include means for
jointly or alternatively operating the outdoor coil and the
solar evaporator coil as ev~porators for the heat pump system
under heating mode. The system preferably includes a
subcooler for subcooling condensed refrigerant within the
primary loop under at least system heating mode and means
for selectively returning vaporized refrigerant to the low
stage or high stage cylinders of the compressor.
Figure 1 is a hydraulic schematic circuit diagram
o the improved solar augmented air source heat pump system
with automatic staging reciprocating compressor. ~;
Figure 2 is the schematic diagram of Figure 1 with
the heat pump system of Figure 1 in single stage compressor, `
solar evaporator heating mode.
Figure 3 is the schematic diagram of Figure 1 with
the heat pump system in high ambient air source evaporator
heating mode~
Figure 4 is the schematic diagram of Figure 1
with the heat pump system in low ambient air source
evaporator, staged compressor and subcooling operation, i
heating mode.
Figure 5 is the schematic diagram of Figure 1 with
the heat pump system in air source condenser, cooling mode.
The presen~ invention is illustrated in schematic
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107096B
diagram form in Figure l as a preferred e~odiment of the
invention. ~he principal components co;mprise a four cylinder
multi-stage reciprocating compressor indicated generally at
lO/ a first heat exchanger 12 conctitutiny the indoor coil,
a second heat exchanger 14 constituting the outdoor coll,
a third heat exchanger 16 constituting the solar augmcnted
evaporator or chiller, a heat sink storage tank 18, a solar
collector 20 for supplying thermal energy to the heat sin~
fluid 22 such as glycoi within the storage tank, a four way
reversing valve 24 and a primary 1GOP subcooler 21. Conduit
means connects the four way reversing valve 24, the
reciprocating compressor 10, the indoor coil 12, and the
outdoor coil 14 in a series, closed primary loop
refrigeration circuit.
In that respect, the reciprocating compressor 10
comprises a left cylinder head 26 and a right cylinder ~ead
28. The left cylinder head 26 includes manifold ~eans 23
and 25 defining a low side 30 and a high side 32 for the
first cylincler 34 and a low side 31 and a high side 33 for
a second cylinder 36. The right cylinder head 28 comprises
a low side 38 and a high side 40 for the compressorls third
cylinder 42 and fourth cylinder ~4, by way of manifold means
45. Compressor inlets for the left cylinder head 26 are
provided at 46, 48 and 50, while a single inlet is
provided for both cylinders 42 and 44 of the right cylinder
head 28 as at 52. A common outlet 54 for both cylinders
42 and 44 is provided for the right cylinder head 28 on the
high sidc 38t while for the compressor left cylinder head 26,
two high side outlets are provided: at 56 for cylincler 36,
and at 58 for cylinder 34.
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3~7~3~68
The primary refrigeration loop incorporating
compressor 10, indoor coil 12 and outdoor coil 14 includes
conduit 60 between four way reversing valve 24 and the
indoor coil 12, conduit 62 between the lndoor coil 12 and
the outdoor coil 14, and conduit 64 from the outdoor coil
14 to the opposite side of the four way reversing valve 24.
Conduit 66 connects the four way revers:ing valve 24 to lef-t
cylinder head inlets 46 and 48 by way of branch lines or
conduits 68 and 70, and employs conduit 67 which terminates
at inlet 52 for the right cylinder head 28. Outlet manifold
72 acts to interconnect the hi.gh sides 32 and 38 of the left
cyli.nder head cylinder 34 and right cylinder head cylinders
42 and 44 to the four way reversing valve 24 through line or
conduit 7~ which extends between the manifold 72 and the
four way reversin~ valve 2~. Line 74 incorporates a check
valve 76 permitting flow from manifold 72 to the four way
reversing valve 24 but preventing reverse flow. The high . ;~
side o. the right cylinder head 28 is connected to the
manifold by way of line or conduit 78 which connects to the
outlet 54 of the compressor right cylinder 28 on the high
side 38. A conduit 80 connects the manifold 72 to the
outlet 58 on the high side 32 of -the left cylinder head
cylinder 34. In addition, a line or conduit 82 connects
outlet 56 of the left cylinder head for cylinder 36 to the
four way reversing valve 24, by intersecting line 74 at
point 84 downstream of the c~eck valve 76.
A further line or conduit 85 connects the manifold
72 to the low side inlet 50 of the compressor left cylinder
head 26 feeding cylinder 36. This line lncludes a solenold
operated control valve 86. Within conduit or branch line 70,

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there is provided a check valve 88 which permits flo~ from
the four way valve 24 to the inlet ~8 for compressor
cylinder 36 but prevt?rlts reverse flow therein.
The subcooler 21 in the illustra-ted en~odiment is
connected within line 62 intermediate of the indoor and
outdoor coils. ~ branch line or conduit 90 carries a
solenoid operated control valve 92 for controlling the bleed
of high pressure liquid refrigerant irom the primary loop
which vaporizes by expansion through a thermal expansion
valve 94 or its equivalent, also within line 90, to subcool
that por-tion of the liquid refrigerant within that portion of
line 62 within subcooler 26, wi-th the vaporized refrigerant
retur~lin~ to the compressor by way of vapor return line or
conduit 96. Conduit 96 intersects conduit 84 at point 98.
The primary refrigerant loop includes solenoid
operated control valve 108 within line 62 and solenoid
operated control valve 107 within conduit or line 6~ to
control primary refrigerant flow so as to direct that flow
either through the outdoor coil 14 or the solar evaporator
coil or chiller 16~ The outdoor coil 14 is provided with
a fan or blower 110 driven by fan motor llOa. The indoor
coil is provided with ~an or blower 112 driven by motor 112a.
These are appropria-tely energized for operation to iorce
ambient air and indoor air over the coils respectively in
conventional fashion.
The solar assist air source heat pump system of the
present invention employs the solar collectors 20 as an
alternate source of heat by solar impingement as at 114, the
solar collectors 20 being connected to tne storage tank by
way oi a closed loop conduit 116 including coil 118 immersecl
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within the glycol or heat sink medium 22. In turn, the
glycol circulates between the solar assist chill~r or
evaporator 16 by way of conduit means 120. Flulds, therefore,
perform the heat transfer of heat randomly from the solar
collector to the storage tank heat sink medium 22 and upon
demand from that medium to the chiller 16. Conduit means
120 incornorates solenoid operated control valve 124 and
pump 122 for forced circulation of the glycol 22.
In order to effec-t the automatic control of the ~ ;
solar augmented air source heat pump system of the present ~-:
invention, th~ solenoid operated control valve 124 is ;~
connected to a control panel 126 by line 128, while the pump .
122 is connected by line 130 to the same control panel. The
control panel 126 is energized through lines 132 from an
electrical source (not shown). Providing input signals to
the control panel 126 to effect control of the four way :~
reversing valve 24 and solenoid control valves86, 9?~ 107,
108 and 122 and pump 124 are: thermobulb or temperature
sensor 134 mounted within the storage tank 18 and immersed .
within the heat sink fluid 22, thermobulb or temperature
sensor 136 within the air stream of ambient air passing over :
the surface of the second heat exchanger or outdoor coil 14 .:
and thermobulb or temperature sensor 138 positioned in the ~`
path of the indoor air which moves over the indoor coil ].2. -
Alternatively, thermobulb 138 may be placed in the room or ~ :
other environment being treated by indoor coil 12. The
control or power signals emanate from control panel 126 and
pass to the various valves including four way reversing
valve 24.
Thermobulb 134 is connected to the control panel
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7~6~3 ~
126 by line 140, thermobulb 136 to the control panel 12G
by line 14~ and thermobulb 138 to -the control panel 126 by
line 1~4.
Further, line 150 connec-ts -the solenoid operated
control valve 108 to the same control panel and companion
valve 107 is connected thereto by line 147. Line 1~8 connects
the solenoid operated con-trol valve 86 to tha-t panel,
and line 152 connects the solenoid operated control valve
92 to said control panel. Fan motor llOa is connected to
the source via control panel 126 by line 156, and the
electric motor 112a, driving fan 112, is connected to the
control panel 126 by way of line 158.
Since the system comprises a reversible
refrigeration system, the indoor coil 12 and the outdoor
coil 14 must operate as evaporator and condenser coils
alternately and respectively when the sys-tem is under
cooliny and heating modes. Expansion means must be
provided on the inlet sides of those coils when acting as
evaporators, as well as chiller 16, to effect expansion o~
the high pressure liquid refrigerant within the coils for the
purpose of absorbing heat. For simplicity, the expansion
devices are not shown, and likewise, while the subcooler 21 is
illustrated as being associated with the indoor coil and
functioning only when the indoor coil acts as a condenser,
appropriately the subcooler may be incorporated within the
system such that it will function to subcool liquid
refrigerant delivered to the indoor coil 12 under cooling
mode with tha-t coil functioning as an evaporator rather than
a con,-lenser. In that respect, further reference may be had
to United States Patent No. ~,086,072, dated
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~C~7~9f~3
A~ril 25, 1~7S,entitled "~I~ SOURC~ AT PUMP WIT~I
l`~lULl'IPLE SLIDE RO'rARY SCRE:W COM:P:RESSOR/EXPANDER" by the same
inventor and assigned ~o the common assignee. The control
panel 126 is of conventional design and functions to compare
the temperature of the li~uid medium 22 stored within the
storage tank 18 and the temperature of the ambient air as
provided by signals from temperature sensors 134 and 136
respectively for in turn controlling the condition of
solenoid operated control valves 107 and 108 for controlling
the flow of primary loop refrigerant through outdoor coil 14
and solar assist chiller or evaporator 16. In the illustrated
en~odiment of the invention, the con-trol panel 126 comprises
conventional circuitry including relays and the like for
actua-tiny selectively the reversing valve 24 and the solenoid
operated control valves 86, 92, 107 and 108 in response to
signals emanating from the temperature sensors 134, 136 and
138 and transmitted to that panel.
The operation of the improved air source heat pump
system of the present invention may be seen under various
modes by reference to Figures 2-5.
Turning first to Fiaure 2, the system is shown
under a heating mode, wherein the indoor coil 12 is
functioning as a condenser, the outdoor coil 14 is not in
operation, fan 110 is turned off, solar evaporator or chiller
16 is functioning as the evaporator coil absorbing heat ~rom
the heat sink storage medium 22 as received from the solar
collectors 20 and the compressor 10 is acting as a single
stage compressor. The operation is autcmatically controlled.f
Thermobulb 13S associated with the room or other controlled
environment, senses the temperature of the air passing over

~L~)7~68
the indoor coil 12, denotes the necessity to heat that
environment and initiates a control signal from the control
panel 12~ to the four way reversing val~e 24 by way of control
line 154 to keep the control valve in position such that
conduits or ].ines 64 and 66 are connected together, such that
lo~ pressure refrigerant vapor discharg:ing from the solar
assist evaporator 16 is directed to inlets 46 and 48 of the
left cylinder head 26 cylinders 34 and 36, and by way of
inlet 52 at the low side of the right cylinder head 28 for
both cylinders 42 and 44. The four way reversing valve 24
further makes a connection between lines 60 and 74 such that
compressed refrigerant vapor or gas under single stage
compression is provided to the indoox coil 12 acting as the
condenser for the primary loop, the refrigerant being
compressed by the individual cylinders 34, 36, 42 and 44
and discharging in parallel by way of out-lets 54, 56 and 58
and passing by way of manifold 72 for outlets 54 and 58
through line 74 with outlet 52 dischargin~ compressed
refrigerant vapor into line 82 leading to line 74 downstream
of the check valve 76. 9
Further, the control panel senses the temperature of -
the ambient air adjacent the outdoor coil 14 by way of .
temperature sensor 136 and senses the temperature of the heat
sink media 22 within the storage tank 18 by means of
temperature sensor 134, and signals are sent via lines 142
and 140 respectively to the comparator of control panel 126. :
Under the mode of Figure 2, the temperature of the
heat sink media such as glycol 22 within the storage tank 18
is warmer than the ambient passing over the outdoor coil 14
by ~ predetermined amount, and a control signal is sent via
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line 147 from control panel 126 to the solenoid operated
control valve 107 within line 65. The solenoid operated
control valves of the illustrated embodiment are of the
normally closed type and open when energized, therefore,
valve 107 is energized while valve 108 is not. The
refrigerant within the primary loop is prevented from
flowing through line 64 and the outdoor coil 14 and is
bypassed to the solar evaporator or chiller 16. At the
same time, pump 126 and solenoid operated valve 124 are
energi2ed so that the glycol is circulated in a closed loop
including tank 18 and solar evaporator 16; current emanating
from the control panel 126 and passing to elements 122 and
124 via lines 130 and 128 respectively. Further, since the
ambient temperature is relatively high, there is no
necessity for operating the reciprocating compressor lO in
multi-stage mode, and therefore, the control panel 126 does
not energize solenoid operated control valves 86 and 9~,
and the system subcooler is not operated. rrhe heat load of
indoor coil 12 is ade~uately supplied in this mode by chiller
16.
Turning ~ext to Figure 3, the heat pump system is
still operating under the heating mode, and at relatively
high ambient temperature. However, the temperature of the
glycol 22 within storage tank 18 has dropped below the
predetermined differential between that temperature and the
temperature of the ambient air passing over the outdoor coil
14 as sensed by temperature sensor 136. Temperature sensor
l38 associated with the indoor coil 12 is still calling for
heat, and therefore the indoor coil must function as a
condenser, thus the four way reversing valve 24 remains under
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~:D7~
under the same condition of the operation as in Figure 2.
The con-trol panel 126 terminates the energization of the
solenoid operated control valve 107 which then au-tomatically
closes and the control panel energizes the solenoid operated
control valve 108 placing the ou-tdoor coil 14 in the primary
loop in place of -the solar evaporator 16. At the same time,
current passes via line 156 from panel 126 to the fan motor
ll~a energizing that motor,causing forced air circulation
over outdoor coil 14. At the same time, pump 122 and
solenoid operated valve 12~ are de-energized, terminating
circulation of glycol from the storage tank 18 to the solar
evaporator 16. Heat, however, is continuously absorbed by
the solar collectors 20 as shown by radiation 114, assuming
proper solar conditions, and the tempexature of the glycol
is raised. Thus, even though there is no sol.ar energy
applied to the heat pump system, solar energy is being stored :within tank 18 and the temperature of the glycol is
increasing. I~hile not shown, the system can be operated
such that the solar evaporator may act in addition to and in
parallel with the air source evaporator 14. Both solenoid
operated control valves 107 and 108 are energized to permit
primary loop refrigerant to flow through lines 64 and 65
simultaneously, picking up heat both from the storage tank
18 and from the ambient air passing over the outdoor coil 14.
As the ambient temperature drops~ and assuming
that there is no solar energy augment because of the low
temperatu-re of the glycol 22 within the storage tank 18, and
further assuming that the environment being conditi.oned is
calling for additional heat by way of temperatur~ sensor 138,
the automatically controlled air source heat pump system of
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~ ~0~68 ~
the present invention reaches a predetermined but typica~
volumetric efficiency switchover point which may be 25~,
as mentioned previously. At~that pointt the system
automatically shifts to the mode of operation illustrated in ~:
Figure 4. The control panel 126 energizes the solenoid
operated control valves 86, 92 and 108 upon energization of
control valve 86, line 84 opens from manifold 72 to the
inlet 50 on the low side of the lef-t cylinder head 26 for
cylinder 36 of compressor 10. Further, the control panel
126 acts to energize the solenoid operated control valve 92 .
with the subcooler in operation, the vaporized refrigeran~
from the return line 96 passes to line 84 leadin~ from the
manifold 72 to inlet 50 on the low side of cylinder 36 o~ -the
left cylinder head 26 of compressor 10. ~nder this mode of
operation, cylinders 34, 42 and 44 are operating to provide
the first stage of compression for the refrigera~t, while
cylinder 36 acts to compress the first stage of refrigerant
vapor discharge in a second stage of compression. Assuming
25~ volumetric efficiency, with the compressor staged there
will be three low side cylinders operating at a volumetric
efficiency of approximately 75~ resulting in 2.25 flow units
in comparison ~o one flow unit~ Thus, the compressor
operates at 2.25 times the volume of flow that it would have
with all ylinders operating single stage at a 12 to 1
compression ratio, greatly lmprovi~g system efficiency in
this mode under such low ambient conditions.
Check valve 76 closes to prevent the high pressure
second stage discharge flow from line 82 to reverse in line
74 towards manifold 72 from point 84 where line 82 mee~s
line 74 upstream of the four way reversing valve 24~ The four
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~C~7~
way reversing valve 24 remains in the condition of E'igures 2
and 3 as the system is still under heating mode. The
second stage discharge by way o outlet 56 through line 82
passes to the four way reversing valve 2~ and thence to
line 60 leading to the indoor coil 12 which is still acting
as the system condenser.
Further, the subcooler efficiently discharges its
refrigerant vapor which is at a higher pressure than the
pressure of the return vapor from the air source evaporator
or outdoor coil 14 to compressor inlets 46, 48 and 52. The
present invention advantageously meets the necessity of
maintaining load reversal on the wrist pins of the
recipxocating compressor pistons and connecting rod assembly,
since cylinder 36 vents the crank case. The co~pressor crank
case and resulting wrist pins are subjected to low side
pressure, which is no problem under single staged operation, - -
but when the compressor 10 is automatically s-tage, the crank
case on the low side for cylinder 36 will be subjected to
intermediate pressure (first stage discharge pressure from
line 85) and the wrist pins and cylinders 34, 42 and 4~
will still undergo proper reversals of loading. The cylinder
36 will also operate with proper wrist pin loading reversal
in that cylinder 36 suction pressure will be applied at the
wrist pin of cylinder 36. This permits the compressor 10 to
be manufactured without expensive, complex and unreliab]e
needle type wrist pin bearings.
It should be noted additionally, that under this
mode of oper~tion, the branch line 70 no longer feeds the low
pressure refrigerant vapor from the discharge side of the
ou-tdoor coil 14 to -the low side of cylinder 36, since vapor
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enters the low si~e of cylinder 36 by way of inlet 50 and is
at a hiyher pressure than the vapor within line 70. The
check valve 88 preven-ts reverse flow from the low side
(first stage discharge) of cylinder 36 into ~he line 66.
The single, reliable and efficient heat pump
system as illustrated, with automatic staging, provides a
fundamental advantage over prior art heat pump systems.
Automatic staging allows the subcooling loop to be
incorporated automat;cally when it is most needed, and the
subcooler automatically feeds the return vaporized
refrigerant to the second stage low side of cylinder 36
by way of inlet S0.
Turning next to Figure 5, the heat pump system is
illustrated under a cooling mode where the outdoor coil 14
functions as an air source condenser. The room or other
envoronment being conditioned by indoor coil 12 now calls
for cooling of that environment and upon receipt of that
signal by the control panel 126 through line 144 from
temperature sensor 138, the control panel 126 directs the
four way reversing valve 24 to shift to the condition shown
in Figure 5 by current application to line 154. Typically,
the four way reversing valve 24 may be a spring biased
solenoid operated valve such that de-energization of the
valve causes lines 64 and 66 to be connected and lines 74
and 60, while upon energization, Figure 5, lines 74 and 64
are in fluid communication and lines 56 and 60 are in fluid
communication, as shown. This functions to direct the high
pressure refrigerant at the discharge side of the compressor
to the outdoor coil 14 which functions as an air souxce
condenser/ the vapor condensing to a liquid for passage to
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the indoor coil 12 which functions as an evaporator coil ~or
the environment or area to be conditioned. As shown, the
compressor 10 is operating with all four cylinders in parallel
in single stage similar to the operation of Figure 3 except
in that case -the system was operating under high ambient
heating mode with heat exchanger 14 forming the air source
evaporator. Under cooling mode conditions, solenoid valves
107, 86, 92 and 12~ are off and solenoid valve 108 is on.
However, in an alternate circuit arrangement, the subcooler
21 may be employed for subcooling the liquid refrigerant
emanating from outdoor coil 14 and feeding indoor coil 12
for absorbing heat from the environment being conditioned.
From the above, it may be seen that the solar
augmented heat pump system of the present invention involves
a control system which permits the reciprocating compressor
to automatically stage itself on demand.
While the reciprocating compressor 10 is illustrated
as having four cylinders which operate in parallel in single
stage and when double staged only one of the four cylinders
acts to compress the vapor in the second stage, it is obvious
that more than four cylinders may be employed, or where four
cylinders are employed, two may operate as ~irst stage
cylinders and the other two as second stage cylinders.
Further, under the staged mode of compressor
operation, it is possible that the solar assist evaporator 16
may have its discharge along with that of the subcooler 21 fed
into the intermediate pressure point of the staged compressor,
that is, the inta~e of the second stage cylinders. I-t is to
be noted that the terms high and low side denote hi~h and low
pressure conditions for the vapor at the compressor.
.