U.S. patent application number 11/630077 was filed with the patent office on 2008-08-21 for refrigerant system with water heating.
This patent application is currently assigned to CARRIER CORPORATION. Invention is credited to Roberto G. Fernandez, Toshio Murakami, Carlos A. Tesche.
Application Number | 20080197206 11/630077 |
Document ID | / |
Family ID | 37481166 |
Filed Date | 2008-08-21 |
United States Patent
Application |
20080197206 |
Kind Code |
A1 |
Murakami; Toshio ; et
al. |
August 21, 2008 |
Refrigerant System With Water Heating
Abstract
A heat pump system (10) includes a compressor (20), a reversing
valve (30), an outdoor heat exchanger (40) and an indoor heat
exchanger (50) coupled via refrigerant lines (35, 45) in a
conventional refrigeration circuit, and a refrigerant-to-water heat
exchanger (60). In the air cooling with water heating mode, the air
heating with water heating mode and the water heating only mode,
water from a water reservoir (64), such as a storage tank or
swimming pool, is passed through heat exchanger (60) in heat
exchange relationship with refrigerant passing through an
additional refrigerant line (27) that establishes a fluid flow path
through the heat exchanger (60) into the refrigerant circuit
intermediate the outdoor heat exchanger (40) and indoor heat
exchanger (50). A refrigerant reservoir (70) may be provided for
use in refrigerant charge control.
Inventors: |
Murakami; Toshio; (Sao
Paulo, BR) ; Tesche; Carlos A.; (Canoas, BR) ;
Fernandez; Roberto G.; (Canoas, BR) |
Correspondence
Address: |
MARJAMA MULDOON BLASIAK & SULLIVAN LLP
250 SOUTH CLINTON STREET, SUITE 300
SYRACUSE
NY
13202
US
|
Assignee: |
CARRIER CORPORATION
Farmington
CT
|
Family ID: |
37481166 |
Appl. No.: |
11/630077 |
Filed: |
June 3, 2005 |
PCT Filed: |
June 3, 2005 |
PCT NO: |
PCT/BR2005/000099 |
371 Date: |
December 10, 2007 |
Current U.S.
Class: |
237/2B |
Current CPC
Class: |
F25B 2313/0315 20130101;
F25B 2700/1933 20130101; F25B 13/00 20130101; F25B 2700/21152
20130101; F25B 40/04 20130101; F25B 2700/1931 20130101; F25B
2313/004 20130101; F25B 2313/0314 20130101; F25B 45/00 20130101;
F25B 2700/21151 20130101 |
Class at
Publication: |
237/2.B |
International
Class: |
F25B 29/00 20060101
F25B029/00 |
Claims
1. A refrigerant system operable in at least an air cooling mode
and having liquid heating capability comprising: a refrigerant
compressor having a suction port and a discharge port; a
selectively positionable reversing valve having a first port, a
second port, a third port and a fourth port, said reversing valve
being positionable in a first position for coupling the first port
and the second port in fluid flow communication and the third port
and the fourth port in fluid flow communication, said reversing
valve being positionable in a second position for coupling the
first port and the fourth port in fluid flow communication and the
second port and the third port in fluid flow communication; a
refrigerant circuit providing a closed loop refrigerant circulation
flow path, said refrigerant circuit having a first refrigerant line
establishing a flow path between the discharge port of said
compressor and the first port of said reversing valve and a second
refrigerant line establishing a flow path between the second port
of said reversing valve and the suction port of said compressor; an
outdoor heat exchanger operatively associated with the second
refrigerant line and adapted for passing refrigerant passing
through the second refrigerant line in heat exchange relationship
with ambient air; an indoor heat exchanger operatively associated
with the second refrigerant line and adapted for passing
refrigerant passing through the second refrigerant line in heat
exchange relationship with the air from the comfort zone, said
indoor heat exchanger disposed downstream of said outdoor exchanger
with respect to refrigerant flow in the air cooling mode; a third
refrigerant line establishing a flow path between the fourth port
of said reversing valve and the second refrigerant line at a
location intermediate said outdoor heat exchanger and said indoor
heat exchanger; a refrigerant to liquid heat exchanger operatively
associated with the third refrigerant line and adapted for passing
refrigerant passing through the third refrigerant line in heat
exchange relationship with a liquid; a first flow control valve
disposed in the second refrigerant line intermediate said outdoor
heat exchanger and the location of the intersection of the third
refrigerant line with the second refrigerant line, said first
control valve having an open position and a closed position; a
second flow control valve disposed in the second refrigerant line
intermediate said indoor heat exchanger and the location the
intersection of the third refrigerant line with said second
refrigerant line, said second control valve having an open position
and a closed position; a controller operatively associated with
said first and second flow control valves, said controller
operative to selectively control the respective positioning of said
first and second flow control valves between their respective open
and closed positions so as to selectively control refrigerant flow
through the second refrigerant line; and a refrigerant reservoir
having an inlet coupled in fluid flow communication to said second
refrigerant line at a location intermediate said outdoor heat
exchanger and said indoor heat exchanger and an outlet coupled in
fluid flow communication to the second refrigerant line at a
location intermediate the indoor heat exchanger and the suction
port of said compressor.
2. A system as recited in claim 1 further comprising a flow check
valve disposed in the third refrigerant line so as to permit
refrigerant flow therethrough in a direction from said reversing
valve into the second refrigerant line and to block flow from the
second refrigerant line to said reversing valve.
3. A system as recited in claim 2 further comprising a fourth
refrigerant line establishing a flow path between a refrigerant
flow path between the third port of said reversing valve and the
suction port of said compressor.
4. A system as recited in claim 1 further comprising: a first flow
control valve operatively associated with said refrigerant
reservoir for controlling the flow refrigerant from the second
refrigerant line to the inlet of said refrigerant reservoir, said
first control valve having an open position and a closed position;
a second flow control valve operatively associated with said
refrigerant reservoir for controlling the flow refrigerant between
the outlet of said refrigerant reservoir and the second refrigerant
line at a location intermediate the indoor heat exchanger and the
suction port of said compressor, said second control valve having
an open position and a closed position; and a controller
operatively associated with said first and second flow control
valves, said controller operative to selectively control the
respective positioning of said first and second flow control valves
between their respective open and closed positions so as to
selectively control the refrigerant charge within the refrigerant
circuit.
5. A system as recited in claim 4 wherein said first and second
flow control valves operatively associated with said refrigerant
reservoir comprise valves having at least one partially open
position between their respective open and closed positions; and
said controller is further operative to selectively modulate the
respective positioning of said first and second flow control valves
operatively associated with said refrigerant reservoir between
their open, at one partially open and closed positions.
6. A system as recited in claim 5 wherein said first and second
flow control valves operatively associated with said refrigerant
reservoir comprise pulse width modulated solenoid valves.
7. A system as recited in claim 4 further comprising a liquid level
sensor operatively associated with said refrigerant reservoir, said
liquid level sensor operative to sense the level of liquid
refrigerant in said refrigerant reservoir and provide a signal
indicative of the liquid level within said refrigerant reservoir to
said controller.
8. A system as recited in claim 7 wherein said controller is
operative to selectively control the respective positioning of said
first and second flow control valves operatively associated with
said refrigerant reservoir between their respective open and closed
positions so as to selectively control the refrigerant charge
within the refrigerant circuit in response to the liquid level
signal received from said liquid level sensor.
9. A refrigerant circuit heat pump system operable in at least an
air cooling mode and an air heating air mode and having liquid
heating capability comprising: a refrigerant compressor having a
suction port and a discharge port; a first selectively positionable
reversing valve having a first port, a second port, a third port
and a fourth port, said reversing valve being positionable in a
first position for coupling the first port and the second port in
fluid flow communication and the third port and the fourth port in
fluid flow communication, said reversing valve being positionable
in a second position for coupling the first port and the fourth
port in fluid flow communication and the second port and the third
port in fluid flow communication; a refrigerant circuit providing a
closed loop refrigerant circulation flow path, said refrigerant
circuit having a first refrigerant line establishing a flow path
between the discharge port of said compressor and the first port of
said first reversing valve and a second refrigerant line
establishing a flow path between the second port of said first
reversing valve and the suction port of said compressor; an outdoor
heat exchanger operatively associated with the second refrigerant
line and adapted for passing refrigerant passing through the second
refrigerant line in heat exchange relationship with ambient air; an
indoor heat exchanger operatively associated with the second
refrigerant line and adapted for passing refrigerant passing
through the second refrigerant line in heat exchange relationship
with the air from the comfort zone, said indoor heat exchanger
disposed downstream of said outdoor exchanger with respect to
refrigerant flow in the air cooling mode; a second selectively
positionable valve having a first port, a second port, a third port
and a fourth port, said second selectively positionable valve being
positionable in a first position for coupling the first port and
the second port in fluid flow communication and the third port and
the fourth port in fluid flow communication, said second
selectively positionable valve being positionable in a second
position for coupling the first port and the third port in fluid
flow communication and the second port and the fourth port in fluid
flow communication; a third refrigerant line establishing a flow
path between the fourth port of said first reversing valve and the
first port of said second reversing valve; a fourth refrigerant
line establishing a flow path between the third port of said second
reversing valve and the second refrigerant line at a location
intermediate said outdoor heat exchanger and said indoor heat
exchanger; a fifth refrigerant line establishing a flow path
between the second port of said reversing valve and the second
refrigerant line at a location intermediate said indoor heat
exchanger and the suction inlet to said compressor; a refrigerant
to liquid heat exchanger operatively associated with the fourth
refrigerant line and adapted for passing refrigerant passing
through the fourth refrigerant line in heat exchange relationship
with a liquid; a first flow control valve disposed in the second
refrigerant line intermediate said outdoor heat exchanger and the
location the intersection of the third refrigerant line with the
second refrigerant line, said first flow control valve having an
open position and a closed position; a second flow control valve
disposed in the second refrigerant line intermediate said indoor
heat exchanger and the location the intersection of the third
refrigerant line with said second refrigerant line, said second
flow control valve having an open position and a closed position; a
third flow control valve disposed in the second refrigerant line
intermediate the location of the intersection of the fifth
refrigerant line with the second refrigerant line and the suction
inlet to said compressor, said third flow control valve having an
open position and a closed position; and a controller operatively
associated with said first, second and third flow control valves,
said controller operative to selectively control the respective
positioning of said first, second and third flow control valves
between their respective open and closed positions so as to
selectively control refrigerant flow through the second refrigerant
line.
10. A heat pump system as recited in claim 9 further comprising a
flow check valve disposed in the fourth refrigerant line so as to
permit refrigerant flow therethrough in a direction from said
second reversing valve into the second refrigerant line and to
block flow from the second refrigerant line to said second
reversing valve.
11. A heat pump system as recited in claim 9 further comprising: a
sixth refrigerant line establishing a refrigerant flow path between
the third port of said first reversing valve and the suction port
of said compressor; and a seventh refrigerant line establishing a
refrigerant flow path between the fourth port of said second
reversing valve and the suction port of said compressor.
12. A heat pump system as recited in claim 9 further comprising a
refrigerant reservoir having an inlet coupled in fluid flow
communication to the second refrigerant line at a location
intermediate said outdoor heat exchanger and said indoor heat
exchanger and an outlet coupled in fluid flow communication to the
second refrigerant line at a location intermediate the indoor heat
exchanger and the suction port of said compressor.
13. A heat pump system as recited in claim 12 further comprising: a
first flow control valve operatively associated with said
refrigerant reservoir for controlling the flow refrigerant from the
second refrigerant line to the inlet of said refrigerant reservoir,
said first control valve having an open position and a closed
position; a second flow control valve operatively associated with
said refrigerant reservoir for controlling the flow refrigerant
between the outlet of said refrigerant reservoir and the second
refrigerant line at a location intermediate the third flow control
valve associated with the second refrigerant line and the suction
port of said compressor, said second flow control valve having an
open position and a closed position; and a controller operatively
associated with said first and second flow control valves
operatively associated with said refrigerant reservoir, said
controller operative to selectively control the respective
positioning of said first and second flow control valves
operatively associated with said refrigerant reservoir between
their respective open and closed positions so as to selectively
control the refrigerant charge within the refrigerant circuit.
14. A heat pump system as recited in claim 12 further comprising a
liquid level sensor operatively associated with said refrigerant
reservoir, said liquid level sensor operative to sense the level of
liquid refrigerant in said refrigerant reservoir and provide a
signal indicative of the liquid level within said refrigerant
reservoir to said controller.
15. A heat pump system as recited in claim 14 wherein said
controller is operative to selectively control the respective
positioning of said first and second flow control valves
operatively associated with said refrigerant reservoir between
their respective open and closed positions so as to selectively
control the refrigerant charge within the refrigerant circuit in
response to the liquid level signal received from said liquid level
sensor.
16. A heat pump system as recited in claim 9 wherein said
controller is operative to cycle between the indoor air heating
mode and the water heating mode whereby the system may effectively
heat water while also heating air.
17. A heat pump system as recited in claim 9 further comprising: a
first expansion valve disposed in the second refrigerant line
intermediate said outdoor heat exchanger and the first flow control
valve in the first refrigerant line; and a second expansion valve
disposed in the second refrigerant line intermediate said indoor
heat exchanger and the second flow control valve in the second
refrigerant line; said first expansion valve being operative
associated with said outdoor heat exchanger and said second
expansion valve being operatively associated with said indoor heat
exchanger.
18. A heat pump system as recited in claim 17 further comprising: a
first expansion valve bypass line operatively associated with the
second refrigerant line for bypassing refrigerant passing through
the second refrigerant line in a direction from said outdoor heat
exchanger to said indoor heat exchanger around said first expansion
valve and through said second expansion valve.
19. A heat pump system as recited in claim 17 further comprising: a
second expansion valve bypass line operatively associated with the
second refrigerant line for bypassing refrigerant passing through
the second refrigerant line in a direction from said indoor heat
exchanger to said outdoor heat exchanger around said second
expansion valve and through said first expansion valve.
Description
TECHNICAL FIELD
[0001] This invention relates generally to refrigerant systems for
cooling or cooling/heating indoor air and, more particularly, to
such refrigerant systems including auxiliary liquid heating,
including for example heating water for swimming pools, household
water systems and the like.
BACKGROUND ART
[0002] Refrigerant systems, such as air conditioners and reversible
heat pumps are well known in the art and commonly used for cooling
and cooling/heating, respectively, a climate controlled comfort
zone within a residence or a building. A conventional air
conditioner or heat pump refrigerant system includes a compressor,
a suction accumulator, an outdoor heat exchanger with an associated
fan, an indoor heat exchanger 50 with an associated fan, and an
expansion valve operatively associated with the indoor heat
exchanger. A heat pump system further includes a reversing valve
and an additional expansion valve operatively associated with the
outdoor heat exchanger. The aforementioned components are typically
arranged in a closed refrigerant circuit employing the well known
Carnot vapor compression cycle. When operating in the cooling mode,
excess heat absorbed by the refrigerant in passing through the
indoor heat exchanger is rejected to the environment as the
refrigerant passes through the outdoor heat exchanger.
[0003] It is well known in the art that an additional
refrigerant-to-water heat exchanger may be added to a heat pump
system to absorb this excess heat for the purpose of heating water,
rather than simply rejecting the excess heat to the environment.
Further, heat pumps often have non-utilized heating capacity when
operating in the heating mode for heating the climate controlled
zone. For example, each of U.S. Pat. Nos. 3,188,829; 4,098,092;
4,492,092 and 5,184,472 discloses a heat pump system including an
auxiliary hot water heat exchanger. U.S. Pat. No. 5,802,864
discloses an air conditioning system for use in cooling and
dehumidifying air for an interior space while rejecting heat to
several alternative heat sinks, such as the atmosphere, domestic
hot water heating and pool water heating. However, these systems do
not include any device for controlling the refrigerant charge
within the refrigerant circuit. Therefore, while functional, these
systems would not be optimally efficient in all modes of
operation.
[0004] In heat pump systems, the outdoor heat exchanger and the
indoor heat exchanger each operate as evaporator, condenser or
subcooler, depending on the mode and point of operation. As such,
condensing may occur in either heat exchangers, and the suction
line may be filled with refrigerant in a gaseous or liquid state.
As a consequence, the amount of system refrigerant charge required
in each mode of operation in order to ensure operation within an
acceptable efficiency envelope will be different for each mode.
[0005] U.S. Pat. No. 4,528,822 discloses a heat pump system
including an additional refrigerant-to-liquid heat exchanger for
heating liquid utilizing the heat that would otherwise be rejected
to the environment. The system is operable in four independent
modes of operation: space heating, space cooling, liquid heating
and simultaneous space cooling with liquid heating. In the liquid
heating only mode, the indoor heat exchanger fan is turned off,
while in the space cooling and liquid heating mode, the outdoor
heat exchanger fan is turned off. A refrigerant charge reservoir is
provided into which liquid refrigerant drains by gravity from the
refrigerant to liquid heat exchanger during the liquid heating only
mode and the simultaneous space cooling and liquid heating mode.
However, no control procedure is disclosed for actively controlling
refrigerant charge in the refrigerant circuit in all modes of
operation. Further, no simultaneous space heating and liquid
heating mode is disclosed.
[0006] Accordingly, it is desirable that the system be provide that
includes active refrigerant charge control in all modes of
operation whereby the heat pump system may operate effectively in
an air cooling only mode, an air cooling and liquid heating mode,
an air heating only mode, an air heating and liquid heating mode,
and a liquid heating only mode.
SUMMARY OF THE INVENTION
[0007] In one aspect, it is an object of the invention to provide
an air conditioner/heat pump system having liquid heating
capability and improved refrigerant charge control.
[0008] In one aspect, it is a object of the invention to provide an
air conditioner/heat pump refrigerant system having liquid heating
capability with refrigerant charge control in all operating
modes.
[0009] In one embodiment of the invention, the system includes a
refrigerant compressor having a suction port and a discharge port;
a selectively positionable four-port reversing valve having a first
position for coupling the first port and the second port in fluid
flow communication and the third port and the fourth port in fluid
flow communication, and a second position for coupling the first
port and the fourth port in fluid flow communication and the second
port and the third port in fluid flow communication; and a
refrigerant circuit providing a closed loop refrigerant circulation
flow path. The refrigerant circuit has a first refrigerant line
establishing a flow path between the discharge port of the
compressor and the first port of the reversing valve, a second
refrigerant line establishing a flow path between the second port
of the reversing valve and the suction port of the compressor. An
outdoor heat exchanger is disposed in operative association with
the second refrigerant line and is adapted for passing refrigerant
passing through the second refrigerant line in heat exchange
relationship with ambient air. An indoor heat exchanger is disposed
inoperative association with the second refrigerant line and is
adapted for passing refrigerant passing through the second
refrigerant line in heat exchange relationship with the air from
the comfort zone. The indoor heat exchanger is disposed downstream
of the outdoor exchanger with respect to refrigerant flow in the
air cooling mode. A third refrigerant line establishes a flow path
between the fourth port of the reversing valve and the second
refrigerant line at a location intermediate the outdoor heat
exchanger and the indoor heat exchanger. A refrigerant to liquid
heat exchanger is disposed in operative association with the third
refrigerant line and is adapted for passing refrigerant passing
through the third refrigerant line in heat exchange relationship
with a liquid. A refrigerant reservoir may be provided having an
inlet coupled in fluid flow communication to the second refrigerant
line at a location intermediate the outdoor heat exchanger and the
indoor heat exchanger and an outlet coupled in fluid flow
communication to the suction inlet of the compressor. A first flow
control valve is disposed in the second refrigerant line
intermediate the outdoor heat exchanger and the location of the
intersection of the third refrigerant line with the second
refrigerant line, and a second flow control valve is disposed in
the second refrigerant line intermediate the indoor heat exchanger
and the location of the intersection of the third refrigerant line
with the second refrigerant line. A controller is provided to
selectively control the respective positioning of the first and
second flow control valves between their respective open and closed
positions so as to selectively control refrigerant flow through the
second refrigerant line. A flow check valve may be disposed in the
third refrigerant line so as to permit refrigerant flow
therethrough in a direction from the reversing valve into the
second refrigerant line and to block flow from the second
refrigerant line to the reversing valve.
[0010] In another embodiment of the invention, a heat pump system
includes a refrigerant compressor having a suction port and a
discharge port; a first selectively positionable four-port valve
having a first position for coupling the first port and the second
port in fluid flow communication and the third port and the fourth
port in fluid flow communication, and a second position for
coupling the first port and the fourth port in fluid flow
communication and the second port and the third port in fluid flow
communication; and a refrigerant circuit providing a closed loop
refrigerant circulation flow path. The refrigerant circuit has a
first refrigerant line establishing a flow path between the
discharge port of the compressor and the first port of the
reversing valve, a second refrigerant line establishing a flow path
between the second port of the reversing valve and the suction port
of the compressor. An outdoor heat exchanger is disposed in
operative association with the second refrigerant line and is
adapted for passing refrigerant passing through the second
refrigerant line in heat exchange relationship with ambient air. An
indoor heat exchanger is disposed inoperative association with the
second refrigerant line and is adapted for passing refrigerant
passing through the second refrigerant line in heat exchange
relationship with the air from the comfort zone. The indoor heat
exchanger is disposed downstream of the outdoor exchanger with
respect to refrigerant flow in the air cooling mode and upstream of
the outdoor heat exchanger with respect to refrigerant flow through
the second refrigerant line in the air heating mode.
[0011] In this embodiment, a second selectively positionable
four-port valve is provided having a first position for coupling
the first port and the second port in fluid flow communication and
the third port and the fourth port in fluid flow communication and
a second position for coupling the first port and the third port in
fluid flow communication and the second port and the fourth port in
fluid flow communication. A third refrigerant line establishes a
flow path between the fourth port of the first reversing valve and
the first port of the second reversing valve. A fourth refrigerant
line establishes a flow path between the third port of the second
reversing valve and the second refrigerant line at a location
intermediate the outdoor heat exchanger and the indoor heat
exchanger. A fifth refrigerant line establishes a flow path between
the second port of the reversing valve and the second refrigerant
line at a location intermediate the indoor heat exchanger and the
suction inlet to the compressor. A refrigerant to liquid heat
exchanger is disposed in operative association with the fourth
refrigerant line and is adapted for passing refrigerant passing
through the fourth refrigerant line in heat exchange relationship
with a liquid. A first flow control valve is disposed in the second
refrigerant line intermediate the outdoor heat exchanger and the
location of the intersection of the third refrigerant line with the
second refrigerant line. A second flow control valve is disposed in
the second refrigerant line intermediate the indoor heat exchanger
and the location of the intersection of the third refrigerant line
with the second refrigerant line. A third flow control valve is
disposed in the second refrigerant line intermediate the location
of the intersection of the fifth refrigerant line with the second
refrigerant line and the suction inlet to the compressor. A
controller is provided to selectively control the respective
positioning of the first, second and third flow control valves
between their respective open and closed positions so as to
selectively control refrigerant flow through the second refrigerant
line. A flow check valve may be disposed in the third refrigerant
line so as to permit refrigerant flow therethrough in a direction
from the reversing valve into the second refrigerant line and to
block flow from the second refrigerant line to the reversing
valve.
[0012] In the heat pump embodiment, as in the air conditioning
embodiment of the system, a refrigerant reservoir may be provided
having an inlet coupled in fluid flow communication to the second
refrigerant line at a location intermediate the outdoor heat
exchanger and the indoor heat exchanger and an outlet coupled in
fluid flow communication to the suction inlet of the compressor.
Advantageously, a first flow control valve may be provided in
operative association with the refrigerant reservoir for
controlling the flow of refrigerant from the second refrigerant
line to the inlet of the refrigerant reservoir; and a second flow
control valve may be provided in operative association with the
refrigerant reservoir for controlling the flow refrigerant between
the outlet of refrigerant reservoir and the suction inlet of the
compressor. The controller selectively controls the respective
positioning of these flow control valves between their respective
open and closed positions so as to selectively control the
refrigerant charge within the refrigerant circuit. These flow
control valves may also have at least one partially open position
and may comprise pulse width modulated solenoid valves. The
controller may be further operative to selectively modulate the
respective positioning of these flow control valves between their
open, partially open and closed positions.
[0013] In a further embodiment, a liquid level sensor may be
provided for sensing the level of liquid refrigerant in the
refrigerant reservoir and for providing a signal to the controller
indicative of the liquid level within the refrigerant reservoir. In
response to the liquid level signal, the controller will
selectively control the respective positioning of the first and
second flow control valves operatively associated with the
refrigerant reservoir so as to selectively control the refrigerant
charge within the refrigerant circuit.
[0014] In a further aspect of the invention, in the heat pump
embodiment, the system may be used to heat both indoor air and
water by cycling between the indoor air heating mode and the water
heating mode. To do so, the system controller will switch between
the air heating only mode and the water heating only mode every few
minutes until the water temperature set point or the air indoor
temperature set point has been reached.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] For a further understanding of these and objects of the
invention, reference will be made to the following detailed
description of the invention which is to be read in connection with
the accompanying drawing, where:
[0016] FIG. 1 is a schematic diagram illustrating a first
embodiment of the system of the invention illustrating operation in
the indoor air cooling only mode;
[0017] FIG. 2 is a schematic diagram illustrating a first
embodiment of the system of the invention illustrating operation in
the indoor air cooling with water heating mode;
[0018] FIG. 3 is a schematic diagram illustrating a first
embodiment of the system of the invention illustrating operation in
the water heating only mode;
[0019] FIG. 4 is a schematic diagram illustrating a second
embodiment of the heat pump system of the invention illustrating
operation in an air cooling only mode;
[0020] FIG. 5 is a schematic diagram illustrating a second
embodiment of the system of the invention illustrating operation in
the indoor air cooling with water heating mode;
[0021] FIG. 6 is a schematic diagram illustrating a second
embodiment of the heat pump system of the invention illustrating
operation in an air heating mode;
[0022] FIG. 7 is a schematic diagram illustrating a second
embodiment of the heat pump system of the invention illustrating
operation in a water heating mode;
[0023] FIG. 8 is a schematic diagram illustrating an embodiment of
a control system arrangement for the system of the invention;
[0024] FIG. 9 is block diagram illustrating a first embodiment of a
refrigerant charge adjustment procedure at start-up in a new mode
of operation;
[0025] FIG. 10 is a block diagram illustrating a second embodiment
of a refrigerant charge adjustment procedure at start-up in a new
mode of operation;
[0026] FIG. 11 is a block diagram illustrating a third embodiment
of a refrigerant charge adjustment procedure at start-up in a new
mode of operation;
[0027] FIG. 12 is a block diagram illustrating a discharge
temperature limit control procedure for adjusting refrigerant
charge post start-up; and
[0028] FIG. 13 is a block diagram illustrating a charge control
procedure for adjusting refrigerant charge post start-up.
DETAILED DESCRIPTION OF THE INVENTION
[0029] The refrigerant heat pump system 10, depicted in a first
embodiment in FIGS. 1-3 and a second embodiment in FIGS. 4-7,
provides in the first embodiment cooling of air to a comfort region
and in the second embodiment cooling and heating of air to a
comfort region, for example an indoor zone located on the inside of
a building (not shown), and also auxiliary water heating in each
embodiment when desired. The system includes a compressor 20, a
suction accumulator 22, a reversing valve 30, an outdoor heat
exchanger 40 and associated fan 42 located on the outside of the
building in heat transfer relation with the surrounding ambient, an
indoor heat exchanger 50 and associated fan 52 situated in the
comfort zone, a first expansion valve 44 operatively associated
with the outdoor heat exchanger 40 and a second expansion valve 54
operatively associated with the indoor heat exchanger 50. A
refrigerant circuit including refrigerant lines 35, 45 and 55
provide a closed loop refrigerant flow path coupling these
components in a conventional manner for a heat pump system
employing the well known Carnot vapor compression cycle.
Additionally, the system 10 includes a refrigerant-to-water heat
exchanger 60 wherein refrigerant is passed in heat exchange
relationship with water to be heated. The water to be heated is
pumped by a circulating pump 62 via water circulation line 65 from
a water reservoir 64, for example a hot water storage tank or a
swimming pool, through the heat exchanger 60 and back to the
reservoir 64.
[0030] The compressor 20, which may comprise a rotary compressor, a
scroll compressor, a reciprocating compressor, a screw compressor
or any other type of compressor, has a suction inlet for receiving
refrigerant from the suction accumulator 22 and an outlet for
discharging compressed refrigerant. The reversing valve 30 may
comprise a selectively positionable, two-position, four-port valve
having a first port 30-1, a second port 30-2, a third port 30-3 and
a fourth port 30-4. The reversing valve 30 is positionable in a
first position for coupling the first port and the second port in
fluid flow communication and for simultaneously coupling the third
port and the fourth port in fluid flow communication. The reversing
valve 30 is positionable in a second position for coupling the
first port and the fourth port in fluid flow communication and for
simultaneously coupling the second port and the third port in fluid
flow communication. Advantageously, the respective port-to-port
couplings established in the first and second positions are
accomplished internally within the reversing valve 30. The outlet
28 of the compressor 20 is connected in fluid flow communication
via refrigerant line 35 to the first port 30-1 of the reversing
valve 30. The second port 30-2 of the reversing valve 30 is
connected in fluid flow communication to refrigerant line 45A. The
third port 30-3 of the reversing valve 30 is connected in fluid
flow with refrigerant line 47. The refrigerant-to-water heat
exchanger 60 is operatively associated with the refrigerant line 25
whereby refrigerant flowing through the refrigerant line 25 passes
in heat exchange relationship with water passing through water
circulation line 65.
[0031] The outdoor heat exchanger 40 and the indoor heat exchanger
50 are operatively disposed in the refrigerant line 45. The outdoor
heat exchanger 50 is connected in fluid flow communication via
section 45A of the refrigerant line 45 with the second port 30-2 of
the reversing valve 30. The indoor heat exchanger 50 is connected
in fluid flow communication to the third port 30-3 of the reversing
valve 30 via section 45C of the refrigerant line 45. Section 45B of
the refrigerant line 45 couples the outdoor heat exchanger 40 and
the indoor heat exchanger 50 in refrigerant flow communication. A
suction accumulator 22 may be disposed in refrigerant line 55 on
the suction side of the compressor 20, having its inlet connected
in refrigerant flow communication to refrigerant line 45C via
section 45C of refrigerant line 55 and having its outlet connected
in refrigerant flow communication to the suction inlet of the
compressor 20 via refrigerant line 55. Therefore, refrigerant lines
35, 45 and 55 together couple the compressor 20, the outdoor heat
exchanger 40 and the indoor heat exchanger 50 in refrigerant flow
communication, thereby creating a closed loop for refrigerant flow
circulation through the heat pump system 10.
[0032] A first flow control valve 48 and a second flow control
valve 58 are disposed in section 45B of refrigerant line 45 between
the outdoor heat exchanger 40 and the indoor heat exchanger 50.
After traversing the refrigerant-to-water heat exchanger 60,
refrigerant line 25 connects in fluid flow communication into
refrigerant line 45 at a point intermediate the two flow control
valves 48 and 58. A check valve 26 disposed in refrigerant line 25
permits flow through line 25 into refrigerant line 45, but closes
line 25 to flow in the reverse direction. Advantageously, both of
the flow control valves 48 and 58 are solenoid valves selectively
positionable by controller 100 in either the open position or the
closed position.
[0033] In the both embodiments, an expansion valve 54 is disposed
in section 45B of the refrigerant line 45 in operative association
with the indoor heat exchanger. In the heat pump embodiment,
illustrated in FIGS. 4-7, an expansion valve 44 is also provided in
operative association with the outdoor heat exchanger. Each of the
expansion valves 44 and 54 is provided with a bypass line equipped
with a check valve permitting flow in only one direction. Check
valve 46 in bypass line 43 associated with the outdoor heat
exchanger expansion valve 44 passes refrigerant flowing from the
outdoor heat exchanger 40 to the indoor heat exchanger 50, thereby
bypassing the outdoor heat exchanger expansion valve 44 and passing
the refrigerant to the indoor heat exchanger expansion valve 54.
Conversely, check valve 56 in bypass line 53 associated with the
indoor heat exchanger expansion valve 54 passes refrigerant flowing
from the indoor heat exchanger 50 to the outdoor heat exchanger 40,
thereby bypassing the indoor heat exchanger expansion valve 54 and
passing the refrigerant to the outdoor heat exchanger expansion
valve 44.
[0034] In the embodiment of the system depicted in FIGS. 4-7, the
system includes, in addition to the previously mentioned
components, a second reversing valve 130 and an additional flow
control valve 68. The second reversing valve 130 may comprise a
selectively positionable, two-position, four-port valve having a
first port 130-1, a second port 130-2, a third port 130-3 and a
fourth port 130-4. The second reversing valve 130 is positionable
in a first position for coupling the first port and the second port
in fluid flow communication and for simultaneously coupling the
third port and the fourth port in fluid flow communication. The
reversing valve 130 is positionable in a second position for
coupling the first port and the third port in fluid flow
communication and for simultaneously coupling the second port and
the fourth port in fluid flow communication. Advantageously, the
respective port-to-port couplings established in the first and
second positions are accomplished internally within the reversing
valve 30. The first port 130-1 of the reversing valve 130 is
connected in refrigerant flow communication via refrigerant line 23
to the fourth port 30-1 of the reversing valve 30. The second port
130-2 of the reversing valve 130 is connected in refrigerant flow
communication via refrigerant line 27 into refrigerant line 45C.
The third port 130-3 of the reversing valve 130 is connected in
refrigerant flow communication via refrigerant line 25 into
refrigerant line 45B. The fourth port 130-4 of the reversing valve
130 is connected in refrigeration flow communication via
refrigerant line 29 into refrigerant line 47.
[0035] Like the first and second flow control valves 48 and 58, the
third flow control valve 68 may advantageously be a solenoid valve
selectively positionable by controller 100 in either the open
position or the closed position. When flow control valve 68 is in
its open position, refrigerant can flow through refrigerant line
45C to the suction accumulator through line 45C. When flow control
valve 68 is in its closed position, however, refrigerant can not
flow through refrigerant line 45C back to the suction accumulator
through line 45C.
[0036] In the embodiment of the system of the invention depicted in
FIGS. 1-3, the system functions to cool air to a comfort region,
and also to heat water on demand. Therefore, in this embodiment,
the system must operate effectively in an air cooling only mode, an
air cooling and water heating mode, and a water heating only mode.
In the embodiment of the system depicted in FIGS. 4-7, the system
functions to cool and to heat air to a comfort region, and to also
heat water on demand except when in the air heating mode.
Therefore, in this embodiment, the system must operate effectively
in an air cooling only mode, an air cooling and water heating mode,
an air heating only mode, and a water heating only mode. As each of
the outdoor heat exchanger 40, the indoor heat exchanger 50 and the
refrigerant-to-water heat exchanger 60 will operate one as a
condenser, another as an evaporator and another bled of refrigerant
depending on the mode, the refrigerant charge required in each mode
in order to ensure operation within an acceptable efficiency
envelope will be different, the optimal refrigerant charge will
also depend on the operation temperatures within each mode and the
amount of refrigerant within the working and bleed lines for each
mode.
[0037] Accordingly, the system 10 further includes a refrigerant
storage reservoir 70, termed a charge tank, having an inlet
connected in fluid flow communication with the refrigerant line 45
via refrigerant line 71 and an outlet connected in fluid flow
communication with the refrigerant line 45C via refrigerant line
73, a first flow control valve 72 disposed in the refrigerant line
71, and a second flow control valve 74 disposed in the refrigerant
line 73. Each of the first and second flow control valves 72 and 74
has an open position and a closed position so that flow
therethrough may be selectively controlled whereby the refrigerant
charge within the refrigerant circuit may be actively controlled.
Advantageously, each of the first and second flow control valves 72
and 74 may also have at least one partially open position and may
be a pulse width modulated solenoid valve. Additionally, a liquid
level meter 80, such as for example a transducer, may be disposed
in the charge tank 70 for monitoring the refrigerant level within
the charge tank.
[0038] Referring now to FIG. 8, a system controller 100,
advantageously a microprocessor, controls the operation of the
water pump 62, the compressor 20, the reversing valve 30 and other
heat pump components, such as the outdoor heat exchanger fan 42 and
the indoor heat exchanger fan 52, in response to the cooling or
heating demand of the comfort region in a conventional manner
and/or the demand for water heating. In the embodiment depicted in
FIGS. 4-7, the system controller 100 also controls operation of the
second reversing valve 130 and the additional flow control valve
68. In addition, the system controller 100 controls the opening and
closing of the flow control valves 72 and 74 to adjust the
refrigerant charge to coordinate with system requirements for the
various modes of operation. The system controller 100 receives
input signals indicative of various system operational parameters
from a plurality of sensors, including, without limitation, a
suction temperature sensor 81, a suction pressure sensor 83, a
discharge temperature sensor 85, a discharge pressure sensor 87, a
water temperature sensor 89, an outdoor heat exchanger refrigerant
temperature sensor 82, an indoor heat exchanger refrigerant
temperature sensor 84, and a refrigerant temperature sensor 86
disposed in operative association with section 45B of refrigerant
line 45 at a location between the expansion valves 44 and 54.
[0039] The suction temperature sensor 81 and the suction pressure
sensor 83 are disposed in operative association with refrigerant
line 55 near the suction inlet to the compressor 20 as in
conventional practice for sensing the refrigerant temperature and
pressure, respectively, at the compressor suction inlet and for
passing respective signals indicative thereof to the system
controller 100. The discharge temperature sensor 85 and the
discharge pressure sensor 87 are disposed in operative association
with refrigerant line 35 near the discharge outlet to the
compressor 20 as in conventional practice for sensing the
refrigerant temperature and pressure, respectively, at the
compressor discharge outlet and for passing respective signals
indicative thereof to the system controller 100. The water
temperature sensor 89 is disposed in operative association with the
water reservoir 64 for sensing the temperature of the water therein
and for passing a signal indicative of the sensed water temperature
to the system controller 100. The temperature sensor 82 is disposed
in operative association with the outdoor heat exchanger 40 at a
location appropriate for measuring the refrigerant phase change
temperature of refrigerant passing therethrough when the indoor
heat exchanger is operating and for sending a signal indicative of
that sensed temperature to the system controller 100 for
controlling operation of the expansion valve 44. Similarly, the
temperature sensor 84 is disposed in operative association with the
indoor heat exchanger 50 at a location for measuring the
refrigerant phase change temperature of refrigerant passing
therethrough when the outdoor heat exchanger is operating and for
sending a signal indicative of that sensed temperature to the
system controller 100 for controlling operation of the expansion
valve 54. The system controller 100 determines the degree of
superheat from the refrigerant temperature sensed by whichever of
sensors 82 and 84 is associated with the heat exchanger that is
acting as an evaporator in the current operating mode. The
refrigerant temperature sensor 86 operatively associated with
refrigerant line 45 senses the temperature of the refrigerant at a
location between the expansion valves 44 and 54 and passes a signal
indicative of the sensed temperature to the system controller 100.
The system controller determines the degree of subcooling present
from the sensed temperature received from temperature sensor
86.
[0040] Referring now to FIG. 1, in the indoor air cooling only
mode, in response to a demand for cooling, the system controller
100 activates the compressor 20, the outdoor heat exchanger fan 42
and the indoor heat exchanger fan 52 and opens both of the flow
control valves 48 and 58. High pressure, superheated refrigerant
from the compressor 20 passes through refrigerant line 35 to the
reversing valve 30 wherein the refrigerant is directed to and
through section 45A of refrigerant line 45 to the outdoor heat
exchanger 40, which in the air cooling mode functions as a
condenser. With the outdoor heat exchanger fan 42 operating,
ambient air flows through the outdoor heat exchanger 40 in heat
exchange relationship with the refrigerant passing therethrough,
whereby the high pressure refrigerant is condensed to a liquid and
subcooled. With the flow control valves 48 and 58 open, high
pressure liquid refrigerant passes from the outdoor heat exchanger
40 through section 45B of refrigerant line 45 to the indoor heat
exchanger 50, which in the air cooling mode functions as an
evaporator. In passing through section 45B of refrigerant line 45,
the high pressure liquid refrigerant bypass the expansion valve 44
through bypass line 43 and check valve 46 and thence passes through
the expansion valve 54 wherein the high pressure liquid refrigerant
expands to a lower pressure, thereby further cooling the
refrigerant prior to the refrigerant entering the indoor heat
exchanger 50. As the refrigerant traverses the indoor heat
exchanger, the refrigerant evaporates. With the indoor heat
exchanger fan 52 operating, indoor air passes through the indoor
heat exchanger 50 in heat exchange relationship with the
refrigerant thereby evaporating the refrigerant and cooling the
indoor air. The refrigerant passes from the indoor heat exchanger
through section 45C of refrigerant line 45 to the suction
accumulator 22 before returning to the compressor 20 through
refrigerant line 55 connecting to the suction inlet of the
compressor 20. In this air cooling only mode, the check 26 in
refrigerant line 25 is closed and any refrigerant that may be in
line 25, for example refrigerant remaining in the
refrigerant-to-water heat exchanger 60 from a prior water heating
mode, is bleed back to the suction accumulator 22 through line 57
to line 45C.
[0041] Referring now to FIG. 2, when there is a demand for water
heating while the system is in the indoor air cooling mode, the
system controller 100 repositions the reversing valve 30, closes
the flow control valve 48, keeps the flow control valve 58 open,
deactivates the outdoor heat exchanger fan 42, and activates the
water pump 60. With the water pump activated, water is pumped via
water line 65 from water reservoir 64 through heat exchanger 60 in
heat exchange relationship with the high pressure superheated
refrigerant flowing through refrigerant line 25 to heat the water.
Having traversed the heat exchanger 60, the heated water returns to
the reservoir 64. The high pressure superheated refrigerant from
the compressor 20 is directed in the reversing valve 30 from port
30-1 to port 30-4 into the refrigerant line 25. As the refrigerant
passes through the heat exchanger 60, the refrigerant is condensed
and subcooled as it gives up heat to heat the water flowing through
the heat exchanger 60 in heat exchange relationship with the
refrigerant. Having already condensed and subcooled, the
refrigerant pass directly into the refrigerant line 45B through the
check valve 26 in line 25, thereby bypassing the outdoor heat
exchanger 40. With valve 48 closed and valve 58 open, the
refrigerant continues on through the expansion valve 54 and
traverses the indoor heat exchanger 50 wherein the refrigerant is
evaporated as it passes in heat exchange relationship with and
cools the indoor air being circulated through the indoor heat
exchanger 50 via fan 52. The refrigerant vapor leaving the indoor
heat exchanger thence passes through line 45C to line 45C to the
suction accumulator 22 and returns to the compressor 20 through
line 55B. With the reversing valve 30 in this position, ports 30-2
and 30-3 are connected in flow communication thereby coupling line
45A in refrigerant flow communication with refrigerant line 57,
whereby any refrigerant remaining within the outdoor heat exchanger
40 from a prior operating mode will bleed back through lines 45A
and 57 back to the line 45C to the suction accumulator 22.
[0042] Referring now to FIG. 3, when there is a demand for water
heating while the system is off, that is not in the indoor air
cooling mode, the system controller 100 activates the water pump
60, the compressor 20, and the outdoor heat exchanger fan 42, but
not the indoor heat exchanger fan 52, opens flow control valve 48
and closes flow control valve 58. With the pump 60 turned on, water
is pumped via water line 65 from storage tank 64 through heat
exchanger 60 in heat exchange relationship with the high pressure
superheated vapor refrigerant flowing through refrigerant line 25.
Having traversed the heat exchanger 60, the heated water returns to
the reservoir 64. The high pressure superheated refrigerant from
the compressor 20 is directed in the reversing valve 30 from port
30-1 to port 30-4 into the refrigerant line 25. Having already
condensed and subcooled, the refrigerant pass directly into the
refrigerant 45 through the check valve 26 in line 25. With valve 48
open and valve 58 closed, the refrigerant continues on through the
expansion valve 44 and traverses the outdoor heat exchanger 40
wherein the refrigerant is evaporated as it passes in heat exchange
relationship with and cools the ambient air being circulated
through the outdoor heat exchanger 40 via fan 42. With the
reversing valve 30 in this position, ports 30-2 and 30-3 are
connected in flow communication thereby coupling line 45A in
refrigerant flow communication with refrigerant line 45D.
Therefore, the refrigerant vapor leaving the outdoor heat exchanger
passes through line 45A, thence via the reversing valve 30 to line
57, thence to line 45C to the suction accumulator 22 and returns to
the compressor 20 through line 55. With valve 58 closed, any
refrigerant remaining within the indoor heat exchanger 50 from a
prior operating mode will bleed back through line 45C back to the
suction accumulator 22.
[0043] As noted previously, the embodiment of the refrigerant
system 10 depicted in FIGS. 4-7 provides for not only cooling air
to a comfort region, for example an indoor zone located on the
inside of a building (not shown), but also for heating air to the
comfort zone and also auxiliary water heating when desired.
Referring now to FIG. 4, in the indoor air cooling only mode, in
response to a demand for cooling, the system controller 100
activates the compressor 20, the outdoor heat exchanger fan 42 and
the indoor heat exchanger fan 52 and opens both of the flow control
valves 48 and 58. High pressure, superheated refrigerant from the
compressor 20 passes through refrigerant line 35 to the reversing
valve 30 wherein the refrigerant is directed to and through section
45A of refrigerant line 45 to the outdoor heat exchanger 40, which
in the air cooling mode functions as a condenser. With the outdoor
heat exchanger fan 42 operating, ambient air flows through the
outdoor heat exchanger 40 in heat exchange relationship with the
refrigerant passing therethrough, whereby the high pressure
refrigerant is condensed to a liquid and subcooled. With the flow
control valves 48 and 58 open, high pressure liquid refrigerant
passes from the outdoor heat exchanger 40 through section 45B of
refrigerant line 45 to the indoor heat exchanger 50, which in the
air cooling mode functions as an evaporator. In passing through
section 45B of refrigerant line 45, the high pressure liquid
refrigerant bypass the expansion valve 44 through bypass line 43
and check valve 46 and thence passes through the expansion valve 54
wherein the high pressure liquid refrigerant expands to a lower
pressure, thereby further cooling the refrigerant prior to the
refrigerant entering the indoor heat exchanger 50. As the
refrigerant traverses the indoor heat exchanger, the refrigerant
evaporates. With the indoor heat exchanger fan 52 operating, indoor
air passes through the indoor heat exchanger 50 in heat exchange
relationship with the refrigerant thereby evaporating the
refrigerant and cooling the indoor air. With the flow control valve
68 open, the refrigerant passes from the indoor heat exchanger
through section 45C of refrigerant line 45 to the suction
accumulator 22 before returning to the compressor 20 through
refrigerant line 55 connecting to the suction inlet of the
compressor 20. In the air cooling only mode, as the check valve 26
in refrigerant line 25 is closed to flow from line 45B, any
refrigerant that may be in line 25, for example refrigerant
remaining in the refrigerant-to-water heat exchanger 60 from a
prior water heating mode, is bleed back through reversing valve 130
and reversing valve 130 to the suction accumulator 22 through line
57 to line 45C.
[0044] Referring now to FIG. 5, when there is a demand for water
heating while the system is in the indoor air cooling mode, the
system controller 100 repositions the reversing valve 30, closes
the flow control valve 48, keeps the flow control valve 58 open,
deactivates the outdoor heat exchanger fan 42, and activates the
water pump 60. With the water pump activated, water is pumped via
water line 65 from water reservoir 64 through heat exchanger 60 in
heat exchange relationship with the high pressure superheated
refrigerant flowing through refrigerant line 25 to heat the water.
Having traversed the heat exchanger 60, the heated water returns to
the reservoir 64. The high pressure superheated refrigerant from
the compressor 20 is directed in the reversing valve 30 from port
30-1 to port 30-4 into the refrigerant line 23 to port 130-1 of the
reversing valve 130 and through the reversing valve 130 to line 25
which connects to port 130-3 of the reversing valve 130. As the
refrigerant passes through the heat exchanger 60, the refrigerant
is condensed and subcooled as it gives up heat to heat the water
flowing through the heat exchanger 60 in heat exchange relationship
with the refrigerant. Having already condensed and subcooled, the
refrigerant pass directly into the refrigerant line 45B through the
check valve 26 in line 25, thereby bypassing the outdoor heat
exchanger 40. With valve 48 closed and valve 58 open, the
refrigerant continues on through the expansion valve 54 and
traverses the indoor heat exchanger 50 wherein the refrigerant is
evaporated as it passes in heat exchange relationship with and
cools the indoor air being circulated through the indoor heat
exchanger 50 via fan 52. With flow control valve 68 open, the
refrigerant vapor leaving the indoor heat exchanger thence passes
through line 45C to the suction accumulator 22 and returns to the
compressor 20 through line 55. With the reversing valves 30 and 130
in this position, ports 30-2 and 30-3 are connected in flow
communication and ports 130-2 and 130-4 are also connected in flow
communication thereby coupling line 45A in refrigerant flow
communication with refrigerant line 57, whereby any refrigerant
remaining within the outdoor heat exchanger 40 from a prior
operating mode will bleed back through lines 45A and 57 back to the
line 45C to the suction accumulator 22.
[0045] Referring now to FIG. 6, in the indoor air heating only
mode, in response to a demand for cooling, the system controller
100 activates the compressor 20, the outdoor heat exchanger fan 42
and the indoor heat exchanger fan 52, closes flow control valve 68,
and opens both of the flow control valves 48 and 58. Further, the
system controller 100 positions the reversing valve 30 such that
port 30-1 communicates with port 30-4 and port 30-2 communicates
with 30-3, and also positions the reversing valve 130 such that
port 130-1 communicates with port 130-2 and port 130-3 communicates
with port 130-4. High pressure, superheated refrigerant from the
compressor 20 passes through refrigerant line 35 to port 30-1 of
the reversing valve 30 wherein the refrigerant is directed to port
30-4 thereof and through refrigerant line 23 to port 130-1 of the
reversing valve 130. From the reversing valve 130, the high
pressure, superheated refrigerant passes from port 130-2 through
refrigerant line 27 and refrigerant line 45C to the indoor heat
exchanger 50, which in the air heating mode functions as a
condenser. With the indoor heat exchanger fan 52 operating, indoor
air flows through the indoor heat exchanger 50 in heat exchange
relationship with the refrigerant passing therethrough, whereby the
high pressure refrigerant is condensed to a liquid and subcooled.
With the flow control valves 48 and 58 open, high pressure liquid
refrigerant passes from the indoor heat exchanger 50 through
section 45B of refrigerant line 45 to the outdoor heat exchanger
40, which in the air heating mode functions as an evaporator. In
passing through section 45B of refrigerant line 45, the high
pressure liquid refrigerant bypass the expansion valve 54 through
bypass line 53 and check valve 56 and thence passes through the
expansion valve 44 wherein the high pressure liquid refrigerant
expands to a lower pressure, thereby further cooling the
refrigerant prior to the refrigerant entering the outdoor heat
exchanger 40. As the refrigerant traverses the outdoor heat
exchanger, the refrigerant evaporates. With the outdoor heat
exchanger fan 42 operating, ambient air passes through the outdoor
heat exchanger 50 in heat exchange relationship with the
refrigerant thereby evaporating the refrigerant and cooling the
ambient air. With the flow control valve 68 closed, the refrigerant
passes from the outdoor heat exchanger 40 through section 45A of
refrigerant line 45 to port 30-2 of the reversing valve 30, thence
from port 30-3 of the reversing valve 30 through line 57 and
refrigerant line 45C to the suction accumulator 22 before returning
to the compressor 20 through refrigerant line 55 connecting to the
suction inlet of the compressor 20. In the air heating only mode,
as the check valve 26 in refrigerant line 25 is closed to flow from
line 45B, any refrigerant that may be in line 25, for example
refrigerant remaining in the refrigerant-to-water heat exchanger 60
from a prior water heating mode, is bleed back through reversing
valve 130 to the suction accumulator 22 through refrigerant line
29, refrigerant line 57 and refrigerant line 45C.
[0046] Referring now to FIG. 7, when there is a demand for water
heating while the system is off, that is not in the indoor air
cooling or indoor heating mode, the system controller 100 activates
the water pump 60, the compressor 20, and the outdoor heat
exchanger fan 42, but not the indoor heat exchanger fan 52, opens
flow control valve 48 and flow control valve 68 and closes flow
control valve 58. With the pump 60 turned on, water is pumped via
water line 65 from storage tank 64 through heat exchanger 60 in
heat exchange relationship with the high pressure superheated vapor
refrigerant flowing through refrigerant line 25. Having traversed
the heat exchanger 60, the heated water returns to the reservoir
64. The high pressure superheated refrigerant from the compressor
20 is directed in the reversing valve 30 from port 30-1 to port
30-4, thence through line 23 to port 130-1 of the reversing valve
130-1 and through port 130-3 into the refrigerant line 25. Having
traversed the refrigerant-to-water heat exchanger 60, the already
condensed and subcooled refrigerant pass directly into refrigerant
line 45 through the check valve 26 in line 25. With valve 48 open
and valve 58 closed, the refrigerant continues on through the
expansion valve 44 and traverses the outdoor heat exchanger 40
wherein the refrigerant is evaporated as it passes in heat exchange
relationship with and cools the ambient air being circulated
through the outdoor heat exchanger 40 via fan 42. With the
reversing valve 30 in this position, ports 30-2 and 30-3 are
connected in flow communication thereby coupling line 45A in
refrigerant flow communication with refrigerant line 45D.
Therefore, the refrigerant vapor leaving the outdoor heat exchanger
passes through line 45A, thence via the reversing valve 30 to line
57, thence to line 45C to the suction accumulator 22 and returns to
the compressor 20 through line 55. With valve 58 closed and valve
68 open, any refrigerant remaining within the indoor heat exchanger
50 from a prior operating mode will bleed back through line 45C to
the suction accumulator 22.
[0047] As noted hereinbefore, in the embodiment of the system of
the invention depicted in FIGS. 1-3, the system must operate
effectively in an air cooling only mode, an air cooling and water
heating mode, and a water heating only mode. In the embodiment of
the system of the invention depicted in FIGS. 4-7, the system must
additionally operate effectively in an air heating mode. As each of
the outdoor heat exchanger 40, the indoor heat exchanger 50 and the
refrigerant-to-water heat exchanger 60 will operate one as a
condenser, another as an evaporator and another bled of refrigerant
depending on the mode, the refrigerant charge required in each mode
in order to ensure operation within an acceptable efficiency
envelope will be different, the optimal refrigerant charge will
also depend on the operation temperatures within each mode and the
amount of refrigerant within the working and bleed lines for each
mode. Accordingly, the system controller system 100 controls the
amount of refrigerant flowing through the refrigerant circuit at
any time, i.e. the refrigerant charge, by monitoring and adjusting
the level of refrigerant in the charge tank 70 by selectively
opening and closing the first flow control valve 72 disposed in the
refrigerant line 71 and a second flow control valve 74 disposed in
the refrigerant line 73.
[0048] In a most advantageous embodiment, the charge tank 70 is
provided with a liquid level meter 80 that generates and transmits
a signal indicative of the refrigerant level within the charge tank
70 to the system controller 100. The liquid level meter 80 may be
configured to transmit a liquid level signal to the system
controller 100 continuously, on a periodic basis at specified
intervals, or only when prompted by the controller. Referring now
to FIG. 9, in operation, when the controller switches from one mode
of operation to a new mode of operation, the controller 100 turns
on the compressor 20 at block 101, and then, at block 102, the
controller 100 compares the then current liquid level in the charge
tank 70 with the liquid level last experienced the last time the
system was operated in a mode equivalent to the new mode of
operation, the liquid level last experienced having been stored in
the controller's memory. If the current level is the same as the
last experienced level for this particular mode of operation, the
controller at block 105 activates the normal charge control
procedure and/or discharge temperature control procedure.
[0049] However, if the current liquid level is not the same as the
last experienced level for this particular mode of operation, the
controller 100 will selectively modulate the solenoid valves 72 and
74 to open and close as necessary to adjust the current liquid
level to equal the last experienced level for this particular mode
of operation. If the current level is below the last experienced
level, at block 103 the controller 100 will close the solenoid
valve 74 and modulate the solenoid valve 72 open to drain
refrigerant from the refrigerant circuit into the charge tank 70
until the current reaches the last experience level. Conversely, if
the current level is above the last experienced level, the
controller 100 at block 104 will close the solenoid valve 72 and
modulate the solenoid valve 74 open to drain refrigerant from the
charge tank 70 into the refrigerant circuit until the current
liquid level reaches the last experienced level. For example, the
controller will open the appropriate valve for a short period of
time, for example 2 seconds, close the valve, recheck the level and
repeat this sequence until the current liquid level equalizes to
the last experience level. Once the current level has been
equalized to the last experienced level, the controller at block
105 activates the normal charge control procedure and/or discharge
temperature control procedure.
[0050] The system controller 100 may also employ the control
procedure discussed herein in embodiments of the heat pump system
of the invention that do not include a liquid level sensor in
association with the charge tank 70. However, when the heat pump
system switches to a new operation mode, the system controller 100
first fills the charge tank either with refrigerant in the liquid
state or with refrigerant in the gas state depending upon the
volume of refrigerant charge required for efficient operation of
the refrigerant to water heat exchanger 60 vis-a-vis the volume of
refrigerant charge required for efficient operation of either the
outdoor air-to-refrigerant heat exchanger 40 or the indoor heat
air-to-refrigerant exchanger 50 depending upon the particular mode
of operation being entered.
[0051] If the new mode of operation involves air cooling, whether
air cooling only or air cooling with water heating, the system
controller will proceed either to fill the refrigerant tank 70 with
liquid refrigerant according to the procedure illustrated by the
block diagram in FIG. 10 if the volume of refrigerant charge
required for efficient operation of the refrigerant to water heat
exchanger 60 is significantly greater than the volume of
refrigerant charge required for efficient operation of either the
outdoor air-to-refrigerant heat exchanger 40, or to fill the
refrigerant tank 70 with gaseous refrigerant according to the
procedure illustrated by the block diagram in FIG. 11 if the volume
of refrigerant charge required for efficient operation of the
refrigerant to water heat exchanger 60 is significantly less than
the volume of refrigerant charge required for efficient operation
of either the outdoor air-to-refrigerant heat exchanger 40. If the
new mode of operation involves indoor air heating or water heating
only, the system controller will proceed either to fill the
refrigerant tank 70 with liquid refrigerant according to the
procedure illustrated by the block diagram in FIG. 10 if the volume
of refrigerant charge required for efficient operation of the
refrigerant to water heat exchanger 60 is significantly greater
than the volume of refrigerant charge required for efficient
operation of either the indoor air-to-refrigerant heat exchanger
50, or to fill the refrigerant tank 70 with gaseous refrigerant
according to the procedure illustrated by the block diagram in FIG.
11 if the volume of refrigerant charge required for efficient
operation of the refrigerant to water heat exchanger 60 is
significantly less than the volume of refrigerant charge required
for efficient operation of either the indoor air-to-refrigerant
heat exchanger 50. However, in any air cooling operating mode, if
the volume of refrigerant charge required for efficient operation
of the refrigerant to water heat exchanger 60 is relatively equal
to the volume of refrigerant charge required for efficient
operation of the outdoor air-to-refrigerant heat exchanger 40, then
the system controller 100 will enter the new mode of operation
without adjusting the refrigerant level in the refrigerant charge
tank 70. Similarly, in the air heating or water heating modes of
operation, if the volume of refrigerant charge required for
efficient operation of the refrigerant to water heat exchanger 60
is relatively equal to the volume of refrigerant charge required
for efficient operation of the indoor air-to-refrigerant heat
exchanger 50, then the system controller 100 will enter the new
mode of operation without adjusting the refrigerant level in the
refrigerant charge tank 70.
[0052] Referring now to FIG. 10, to fill the refrigerant charge
tank 70 with liquid refrigerant, after turning the compressor 20 on
at block 201, the system controller at block 202 closes solenoid
valve 74 and opens solenoid valve 72 to allow liquid refrigerant to
pass from line 71 into the charge tank 70. After a programmed time
delay at block 203 sufficient to allow the charge tank 70 to fill
with liquid refrigerant, for example about 3 minutes, the system
controller at block 205 proceeds to adjust the refrigerant circuit
charge as need by the discharge temperature control procedure
and/or the charge control procedure as desired. The solenoid valve
72 may be positioned either open or closed at this point.
[0053] Referring now to FIG. 11, to fill the refrigerant charge
tank 70 with gaseous refrigerant, after turning the compressor 20
on at block 211, the system controller at block 212 closes solenoid
valve 72 and modulates solenoid valve 74 on/off for a period of
time, for example open 3 seconds, closed 17 seconds repeatedly for
two minutes, to allow refrigerant in the gas state to pass from
line 73 into the charge tank 70. After a programmed time delay at
block 213 sufficient to allow the charge tank 70 to fill with
gaseous refrigerant, for example about 3 minutes, the system
controller at block 214 proceeds to adjust the refrigerant circuit
charge as need by the discharge temperature control procedure
and/or the charge control procedure as desired. The solenoid valve
74 may be positioned either open or closed at this point. In any
water heating mode, the controller 100 will shut the pump 62 off
when temperature sensor 89 detects that the water temperature in
water reservoir 64 has reached a desired limit value, for example
60 degrees C.
[0054] In accord with the discharge temperature limit control
procedure, illustrated by the block diagram of FIG. 12, after a
brief time delay, for example about 30 seconds, following turning
on the compressor at block 301, the system controller compares at
block 302 the current discharge temperature, TDC, i.e. the
temperature of the refrigerant discharging from the compressor 20,
received from temperature sensor 150 to a discharge temperature
limit, TDL, preprogrammed into the controller 100. A typical
compressor discharge limit might be a desired number of degrees,
for example about 7 degrees C., below the manufacturer's
application guide specification. A typical compressor discharge
temperature limit would be about 128 degrees C. If the current
discharge temperature, TDC, exceeds the discharge temperature
limit, the system controller 100 at block 303 deactivates the
charge control procedure if it is currently active, and then at
block 304 closes the solenoid valve 72 and modulates the solenoid
valve 74 open to drain refrigerant from the charge tank 70 into the
refrigerant circuit through the refrigerant line 73. If the current
discharge temperature received from temperature sensor 150 is equal
to or below the discharge temperature limit, the system controller
100 at block 305 activates the charge control procedure if it is
not currently active and proceeds to follow the charge control
procedure to adjust the refrigerant charge in the refrigerant
circuit as necessary.
[0055] In the charge control procedure, illustrated in FIG. 13,
with the refrigerant charge initially set, the system controller
100 at block 401 closes both solenoid valves 72 and 74. After a
brief time delay, for example about one minute, depending upon the
particular mode of current operation, the system controller will at
block 402 compare either or both of the degree of superheat or the
degree of subcooling currently present in the system to a
permissible range of superheat preprogrammed into the controller
100. For example, in the air cooling only and the air cooling with
water heating modes, the permissible range of superheat may be from
0.5 to 20 degrees C. and the permissible range of subcooling may be
from 2 to 15 degrees C. In the air heating only, the air heating
with water heating and the water heating only modes, the
permissible range of superheat may be from 0.5 to 11 degrees C. and
the permissible range of subcooling may be from 0.5 to 10 degrees
C., for example.
[0056] If operating in a mode with fixed expansion, the system
controller, at block 403, compares the current degree of superheat
against the permissible range of superheat preprogrammed into the
controller 100. If the current degree of superheat is below the
permissible range, at block 404, the system controller 100 will
modulate the solenoid valve 72 open to drain refrigerant from the
refrigerant circuit into the charge tank 70. If the current degree
of superheat is above the permissible range, at block 405, the
system controller 100 will modulate the solenoid valve 74 open to
drain refrigerant from the charge tank 70 into the refrigerant
circuit. If the degree of superheat falls within the permissible
range of superheat, the system controller proceeds to block
406.
[0057] If operating in a mode without fixed expansion, the system
controller, at block 406, compares the current degree of subcooling
against a permissible range of subcooling programmed into the
controller. If the current degree of subcooling is above the
permissible range, at block 404, the system controller 100 will
modulate the solenoid valve 72 open to drain refrigerant from the
refrigerant circuit into the charge tank 70. If the current degree
of subcooling is below the permissible range, at block 405, the
system controller 100 will modulate the solenoid valve 74 open to
drain refrigerant from the charge tank 70 into the refrigerant
circuit. If the degree of subcooling falls within the permissible
range of subcooling, the system controller proceeds to control
refrigerant charge through the charge control procedure and the
discharge temperature limit control procedure as described.
[0058] The various control parameters presented as examples
hereinbefore, such as compressor discharge temperature limit, the
various time delays, the desired superheat ranges, the desired
subcooling ranges, are for a typical 5 ton capacity, split-system
heat pump system having a brazed plate water to refrigerant heat
exchanger 60, a refrigerant reservoir (charge tank) 70 having a
liquid refrigerant storage capacity of 4 kilograms, a system
refrigerant charge of 8 kilograms, and overall refrigerant lines of
7 meters. These parameters are presented for purposes of
illustration and those skilled in the art will understand that
these parameters may vary from the examples presented for different
heat pump configurations and capacities. Those having ordinary
skill in the art will select precise parameters to be used in
implementing the invention to best suit operation of any particular
heat pump system.
[0059] In the embodiment of the heat pump system of the invention
depicted in FIGS. 4-7, the heat pump system may be used to heat
both indoor air and water by cycling between the indoor air heating
mode and the water heating mode. To do so, the system controller
100 will simply operate the system in the indoor air heating mode
for a desired period, such as a few minutes, then switch to water
heating mode for a desired period, such as a few minutes, and the
switch back to the air heating mode. The system controller will
continue switching from one mode to the other every few minutes
until the water temperature set point or the air indoor temperature
set point has been reached. Importantly, the system controller 100
can effectuate this cycling mode of operation without shutting the
compressor 20 down. To switch from the indoor air heating mode to
the water heating mode, the system controller 100 will reposition
the reversing valve 130 to its second position, activate the water
pump 62, close flow control valve 58 and open flow control valve
68. To return to the indoor air heating mode from the water heating
mode, the system controller 100 will reposition the reversing valve
130 to its first position, turn off the water pump 62, close flow
control valve 68 and open flow control valve 58.
[0060] While the present invention has been particularly shown and
described with reference to the preferred mode as illustrated in
the drawing, it will be understood by one skilled in the art that
various changes in detail may be effected therein without departing
from the spirit and scope of the invention as defined by the
claims.
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