U.S. patent application number 12/921848 was filed with the patent office on 2011-02-03 for refrigerating cycle device.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. Invention is credited to Yusuke Shimazu.
Application Number | 20110023533 12/921848 |
Document ID | / |
Family ID | 41340006 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110023533 |
Kind Code |
A1 |
Shimazu; Yusuke |
February 3, 2011 |
REFRIGERATING CYCLE DEVICE
Abstract
Provided is a refrigerating cycle apparatus in which, even if
large power is required to start up an expander, the expander may
be started up by activating a compressor. An air conditioner
including a first compressor for compressing a refrigerant, an
outdoor heat exchanger for radiating heat of the refrigerant
compressed by the first compressor, an expander for decompressing
the refrigerant that has passed through the outdoor heat exchanger,
an indoor heat exchanger in which the refrigerant decompressed by
the expander is evaporated, and a drive shaft for recovering power
that is generated when the refrigerant is decompressed by the
expander includes an on-off valve which is provided between the
expander and the indoor heat exchanger and controls movement of the
refrigerant from the expander to the indoor heat exchanger. After
the first compressor is started up to increase a pressure of the
refrigerant in the expander to a critical pressure or higher, the
on-off valve is opened and the expander is started up by a dynamic
pressure of the refrigerant.
Inventors: |
Shimazu; Yusuke; (Tokyo,
JP) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
Tokyo
JP
|
Family ID: |
41340006 |
Appl. No.: |
12/921848 |
Filed: |
March 31, 2009 |
PCT Filed: |
March 31, 2009 |
PCT NO: |
PCT/JP2009/056662 |
371 Date: |
September 10, 2010 |
Current U.S.
Class: |
62/498 ;
62/317 |
Current CPC
Class: |
F25B 2500/26 20130101;
F25B 1/10 20130101; F25B 9/008 20130101; F25B 2400/0401 20130101;
F25B 2313/02541 20130101; F25B 2400/14 20130101; F25B 2313/02742
20130101; F25B 13/00 20130101; F25B 2309/061 20130101; F25B
2313/02533 20130101; F25B 9/06 20130101; F25B 2400/072
20130101 |
Class at
Publication: |
62/498 ;
62/317 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F25D 23/00 20060101 F25D023/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 22, 2008 |
JP |
2008-134298 |
Claims
1. A refrigerating cycle apparatus including: a first compressor
for compressing a refrigerant; a radiator for radiating heat of the
refrigerant compressed by the first compressor; an expander for
decompressing the refrigerant that has passed through the radiator;
an evaporator in which the refrigerant decompressed by the expander
is evaporated; and a power recovery device which is connected to
the expander and recovers power that is generated when the
refrigerant is decompressed by the expander, the refrigerating
cycle apparatus comprising refrigerant movement control means which
is provided in a channel of the refrigerant from the expander to
the evaporator and controls a flow rate of the refrigerant moving
from the expander to the evaporator, wherein, after the first
compressor is started up to increase a pressure of the refrigerant
in the expander, the refrigerant movement control means controls
the flow rate of the refrigerant to start up the expander by a
dynamic pressure of the refrigerant in the expander.
2. A refrigerating cycle apparatus according to claim 1, wherein
the refrigerant movement control means controls the flow rate of
the refrigerant when the pressure of the refrigerant at an inlet of
the refrigerant of the expander is equal to or higher than a
critical pressure.
3. A refrigerating cycle apparatus according to claim 1, wherein
the refrigerant movement control means controls the flow rate of
the refrigerant when a difference between the pressure of the
refrigerant at an inlet of the refrigerant of the refrigerant
movement control means and the pressure of the refrigerant at an
outlet thereof is equal to or larger than 2.5 MPa.
4. A refrigerating cycle apparatus according to claim 1, further
comprising: judging means for judging, after the refrigerant
movement control means controls the flow rate of the refrigerant,
whether or not the expander is started up; storage means for
storing a number of times the judging means judges that the
expander is not started up; and display means for displaying, when
the number of times stored in the storage means has reached a
predetermined number of times, a notification that the expander has
failed.
5. A refrigerating cycle apparatus according to claim 4, further
comprising, in a channel of the refrigerant between the radiator
and the evaporator, a bypass circuit connected in parallel to the
expander and the refrigerant movement control means that are
connected in series, and a bypass valve for adjusting the flow rate
of the refrigerant passing through the bypass circuit, wherein the
refrigerant is allowed to pass through the bypass circuit when the
number of times stored in the storage means has reached the
predetermined number of times.
6. A refrigerating cycle apparatus according to claim 1, wherein
the refrigerant movement control means comprises an on-off valve
that is fully closed to restrict movement of the refrigerant from
the expander to the evaporator and is fully opened to control the
flow rate of the refrigerant moving from the expander to the
evaporator.
7. A refrigerating cycle apparatus according to claim 1, wherein
the refrigerant movement control means comprises a flow regulating
valve that is totally closed or nearly totally closed to restrict
movement of the refrigerant from the expander to the evaporator and
is adjusted in degree of opening to control the flow rate of the
refrigerant moving from the expander to the evaporator.
8. A refrigerating cycle apparatus according to claim 1, wherein
the power recovery device comprises a power generator.
9. A refrigerating cycle apparatus according to claim 1, further
comprising, in a channel of the refrigerant between the first
compressor and the radiator, a second compressor for compressing
the refrigerant, wherein the power recovery device comprises one
drive shaft which is connected between the expander and the second
compressor and transfers the power from the expander to the second
compressor.
10. A refrigerating cycle apparatus according to claim 1, further
comprising, in a channel of the refrigerant between the first
compressor and the evaporator, a second compressor for compressing
the refrigerant, wherein the power recovery device comprises one
drive shaft which is connected between the expander and the second
compressor and transfers the power from the expander to the second
compressor.
11. A refrigerating cycle apparatus according to claim 1, further
comprising a first foreign particle trap for trapping foreign
particles entering the expander at an inlet of the refrigerant of
the expander, wherein a size of a smallest one of the foreign
particles to be trapped by the first foreign particle trap is
smaller than a largest gap in an expansion chamber of the
expander.
12. A refrigerating cycle apparatus according to claim 9, further
comprising a second foreign particle trap for trapping foreign
particles entering the second compressor at an inlet of the
refrigerant of the second compressor, wherein a size of a smallest
one of the foreign particles to be trapped by the second foreign
particle trap is smaller than a largest gap in a compression
chamber of the second compressor.
13. A refrigerating cycle apparatus according to claim 1, wherein
the refrigerant comprises carbon dioxide.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigerating cycle
apparatus including a power recovery device for recovering power
that is generated when a refrigerant is decompressed by an
expander.
BACKGROUND ART
[0002] Conventionally, there is known a refrigerating cycle
apparatus including a first compressor for compressing a
refrigerant, a radiator for radiating heat of the refrigerant
compressed by the first compressor, an expander for decompressing
the refrigerant that has passed through the radiator, an evaporator
in which the refrigerant decompressed by the expander is
evaporated, and a power generator which is connected to the
expander, recovers power that is generated when the refrigerant is
decompressed by the expander, and converts the power into
electricity (see, for example, Patent Document 1).
[0003] There is also known a refrigerating cycle apparatus further
including a second compressor which is provided to the expander and
utilizes the power recovered from the expander.
[0004] Patent Document 1: JP 2006-132818 A
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0005] However, in the above-mentioned cases, when the
refrigerating cycle apparatus has been in an inactive state for a
longtime, for example, refrigerator oil in the expander is
increased in viscosity due to low temperature so that large power
is required to start up the expander. Therefore, there has been a
problem in that, even when the first compressor is started up, the
expander may not be able to be started up.
[0006] There has been another problem in that, when foreign
particles enter from an inlet of the refrigerant of the expander or
the second compressor and caught up in a rotating part therein, the
operation continues under inertia of the rotating part in a steady
operating state, but the expander stops in a start-up operating
state because there is no inertia of the rotating part.
[0007] The present invention has been made to solve the
above-mentioned problems, and an object of the present invention is
therefore to provide a refrigerating cycle apparatus in which, even
if large power is required to start up an expander, the expander
may be started up by activating a first compressor.
Means for Solving the Problems
[0008] The present invention provides a refrigerating cycle
apparatus including: a first compressor for compressing a
refrigerant; a radiator for radiating heat of the refrigerant
compressed by the first compressor; an expander for decompressing
the refrigerant that has passed through the radiator; an evaporator
in which the refrigerant decompressed by the expander is
evaporated; and a power recovery device which is connected to the
expander and recovers power that is generated when the refrigerant
is decompressed by the expander, the refrigerating cycle apparatus
including refrigerant movement control means which is provided in a
channel of the refrigerant from the expander to the evaporator and
controls a flow rate of the refrigerant moving from the expander to
the evaporator, in which, after the first compressor is started up
to increase a pressure of the refrigerant in the expander, the
refrigerant movement control means controls the flow rate of the
refrigerant to start up the expander by a dynamic pressure of the
refrigerant.
EFFECTS OF THE INVENTION
[0009] According to the refrigerating cycle apparatus of the
present invention, even if large power is required to start up the
expander, the first compressor is started up to increase the
pressure of the refrigerant in the expander, and then the
refrigerant movement control means controls the flow rate of the
refrigerant so that the expander may be started up by the dynamic
pressure of the refrigerant.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] [FIG. 1] A refrigerant circuit diagram in cooling operation
of an air conditioner according to a first embodiment of the
present invention.
[0011] [FIG. 2] A refrigerant circuit diagram in heating operation
of the air conditioner of FIG. 1.
[0012] [FIG. 3] FIG. 3(a) is a schematic diagram illustrating a
breakdown of power transferred from an expander to a second
compressor in a steady state, and FIG. 3(b) is a schematic diagram
illustrating a breakdown of the power transferred from the expander
to the second compressor during activation.
[0013] [FIG. 4] FIG. 4(a) is a diagram illustrating a pressure of a
refrigerant, a volume of the refrigerant, and a mass of the
refrigerant in the steady state of the expander, and FIG. 4(b) is a
diagram illustrating the pressure of the refrigerant, the volume of
the refrigerant, and the mass of the refrigerant during the
activation of the expander.
[0014] [FIG. 5] A flow chart illustrating start-up operation of the
air conditioner of FIGS. 1 and 2.
[0015] [FIG. 6] A refrigerant circuit diagram of the air
conditioner in a second start-up mode.
[0016] [FIG. 7] A refrigerant circuit diagram of a water heater
according to a second embodiment of the present invention.
[0017] [FIG. 8] A flow chart illustrating start-up operation of the
water heater of FIG. 7.
[0018] [FIG. 9] A refrigerant circuit diagram of a water heater
according to a third embodiment of the present invention.
BEST MODES FOR CARRYING OUT THE INVENTION
[0019] Hereinafter, embodiments of the present invention are
described with reference to drawings. Throughout the drawings, the
same reference symbols are assigned to the same or like members and
parts for description.
First Embodiment
[0020] FIG. 1 is a refrigerant circuit diagram in cooling operation
of an air conditioner according to a first embodiment of the
present invention, and FIG. 2 is a refrigerant circuit diagram in
heating operation of the air conditioner of FIG. 1.
[0021] The air conditioner, which is a refrigerating cycle
apparatus according to this embodiment, includes a first compressor
1 for compressing a refrigerant, an outdoor heat exchanger 2 which
serves as a radiator in which the refrigerant radiates heat in the
cooling operation and as an evaporator in which the refrigerant is
evaporated in the heating operation, an expander 3 for
decompressing the refrigerant passing therethrough, an indoor heat
exchanger 4 which serves as an evaporator in which the refrigerant
is evaporated in the cooling operation and as a radiator in which
the refrigerant radiates heat in the heating operation, and a drive
shaft 5 which is connected to the expander 3 and serves as a power
recovery device for recovering power that is generated when the
refrigerant is decompressed by the expander 3.
[0022] The air conditioner also includes an on-off valve 6 which is
provided downstream of the expander 3 and serves as refrigerant
movement control means that is fully closed to restrict movement of
the refrigerant from the expander 3 to the downstream side and is
fully opened to control a flow rate of the refrigerant moving from
the expander 3 to the downstream side.
[0023] Further, the air conditioner uses carbon dioxide as the
refrigerant. The carbon dioxide refrigerant has an ozone depletion
potential of zero and a smaller global warming potential compared
to the conventional fluorocarbon refrigerant.
[0024] The outdoor heat exchanger 2 includes a first outdoor heat
exchanger portion 2a and a second outdoor heat exchanger portion
2b. In a channel of the refrigerant between the first outdoor heat
exchanger portion 2a and the second outdoor heat exchanger portion
2b, there are provided a switch 7a and a switch 7b which are closed
in the cooling operation to block the refrigerant and opened in the
heating operation to allow the refrigerant to pass
therethrough.
[0025] Therefore, the first outdoor heat exchanger portion 2a and
the second outdoor heat exchanger portion 2b are configured so that
the first outdoor heat exchanger portion 2a and the second outdoor
heat exchanger portion 2b are connected in series in the cooling
operation and the first outdoor heat exchanger portion 2a and the
second outdoor heat exchanger portion 2b are connected in parallel
in the heating operation.
[0026] The indoor heat exchanger 4 includes a first indoor heat
exchanger portion 4a and a second indoor heat exchanger portion 4b,
and the first indoor heat exchanger portion 4a and the second
indoor heat exchanger portion 4b are connected in parallel.
[0027] The first indoor heat exchanger portion 4a is connected to
an indoor expansion valve 8a, and the second indoor heat exchanger
portion 4b is connected to an indoor expansion valve 8b.
[0028] Therefore, the refrigerant is decompressed in the cooling
operation so that the refrigerant may be evaporated in the first
indoor heat exchanger portion 4a and the second indoor heat
exchanger portion 4b, and the refrigerant is decompressed in the
heating operation so that the refrigerant, which has radiated heat
in the first indoor heat exchanger portion 4a and the second indoor
heat exchanger portion 4b, may be evaporated in the first outdoor
heat exchanger portion 2a and the second outdoor heat exchanger
portion 2b.
[0029] In the channel of the refrigerant between the first outdoor
heat exchanger portion 2a and the second outdoor heat exchanger
portion 2b, there is provided a second compressor 9 for compressing
the refrigerant that has passed through the first outdoor heat
exchanger portion 2a in the cooling operation.
[0030] The second compressor 9 is connected to the expander 3
through the drive shaft 5, and hence the power generated in the
expander 3 is recovered by the drive shaft 5 and transferred to the
second compressor 9.
[0031] In the channel of the refrigerant between the first
compressor 1 and the first outdoor heat exchanger portion 2a and
the channel of the refrigerant between the first outdoor heat
exchanger portion 2a and the second compressor 9, there are
provided a switch 10a and a switch 10b which are opened in the
cooling operation to allow the refrigerant to pass therethrough and
closed in the heating operation to block the refrigerant,
respectively.
[0032] In the channel of the refrigerant between the first
compressor 1 and the second compressor 9, there is provided a
switch 7c which is closed in the cooling operation to block the
refrigerant and allows the refrigerant to pass therethrough in the
heating operation.
[0033] At an inlet of the refrigerant of the expander 3, there is
provided a first foreign particle trap 11 for trapping foreign
particles contained in the refrigerant that flows into the expander
3.
[0034] At an inlet of the refrigerant of the second compressor 9,
there is provided a second foreign particle trap 12 for trapping
foreign particles contained in the refrigerant that flows into the
second compressor 9.
[0035] Each of the first foreign particle trap 11 and the second
foreign particle trap 12 includes a strainer made of a coarse metal
mesh. The coarseness of the metal mesh determines the size of the
smallest foreign particles to be trapped.
[0036] The size of the smallest foreign particles to be trapped by
the first foreign particle trap 11 is set to be smaller than the
largest gap in an expansion chamber of the expander 3.
[0037] The size of the smallest foreign particles to be trapped by
the second foreign particle trap 12 is set to be smaller than the
largest gap in a compression chamber of the second compressor
9.
[0038] The size of the smallest foreign particles to be trapped by
each of the first foreign particle trap 11 and the second foreign
particle trap 12 is 0.5 mm. Therefore, a pressure loss caused by
each of the first foreign particle trap 11 and the second foreign
particle trap 12 is decreased, to thereby suppress a reduction of
power to be recovered.
[0039] At an inlet of the refrigerant of the first compressor 1,
there is provided an accumulator 13 for accumulating the
refrigerant before flowing into the first compressor 1.
[0040] In the channel of the refrigerant among the outdoor heat
exchanger 2, the second compressor 9, the indoor heat exchanger 4,
and the accumulator 13, there is provided a first four-way valve
14. Valves in the first four-way valve 14 are switched so that the
refrigerant is allowed to flow from the second compressor 9 to the
second outdoor heat exchanger portion 2b and the refrigerant is
allowed to flow from the indoor heat exchanger 4 to the accumulator
13 in the cooling operation, and the refrigerant is allowed to flow
from the second compressor 9 and a check valve 15 bypassing the
second compressor 9 and the second foreign particle trap 12 to the
indoor heat exchanger 4 and the refrigerant is allowed to flow from
the outdoor heat exchanger 2 to the accumulator 13 in the heating
operation. It should be noted that the check valve 15 may be
included in the second compressor 9.
[0041] In the channel of the refrigerant among the outdoor heat
exchanger 2, the expander 3, and the indoor heat exchanger 4, there
is provided a second four-way valve 16. Valves in the second
four-way valve 16 are switched so that the refrigerant is allowed
to flow from the second outdoor heat exchanger portion 2b through
the expander 3 to the indoor heat exchanger 4 in the cooling
operation, and the refrigerant is allowed to flow from the indoor
heat exchanger 4 through the expander 3 to the outdoor heat
exchanger 2 in the heating operation.
[0042] The first four-way valve 14 and the second four-way valve 16
serve to allow the refrigerant to pass through the expander 3 and
the second compressor 9 in the same direction regardless of the
cooling operation or the heating operation.
[0043] In the channel of the refrigerant between the outdoor heat
exchanger 2 and the indoor heat exchanger 4, there are provided a
bypass circuit 17 for bypassing the second four-way valve 16, the
expander 3, and the on-off valve 6, and a bypass valve 18 for
adjusting the flow rate of the refrigerant passing through the
bypass circuit 17.
[0044] In the channel of the refrigerant between the second
four-way valve 16 and the first foreign particle trap 11, there is
provided a pre-expansion valve 19 for adjusting the flow rate of
the refrigerant moving from the second four-way valve 16 to the
first foreign particle trap 11.
[0045] The bypass valve 18 and the pre-expansion valve 19 are
adjusted so that the flow rate of the refrigerant passing through
the second compressor 9 and the sum of the flow rates of the
refrigerant passing through the expander 3 and the bypass circuit
17 are equal.
[0046] This way, a pressure on the high-pressure side may be
increased to a desirable pressure to be adjusted, and further the
power generated in the expander 3 may be recovered. Therefore, the
refrigerating cycle may be maintained in a highly efficient
state.
[0047] It should be noted that, without limiting to adjusting the
bypass valve 18 and the pre-expansion valve 19, any other method
may be used to adjust the flow rate of the refrigerant passing
through the second compressor 9 and the flow rates of the
refrigerant passing through the expander 3 and the bypass circuit
17 to be equal.
[0048] At an outlet of the refrigerant of the first compressor 1,
there is provided a pressure sensor 20a for measuring a pressure of
the refrigerant that flows out of the first compressor 1. At the
inlet of the refrigerant of the expander 3, there is provided a
pressure sensor 20b for measuring the pressure of the refrigerant
that flows into the expander 3. At an outlet of the refrigerant of
the on-off valve 6, there is provided a pressure sensor 20c for
measuring the pressure of the refrigerant that flows out of the
on-off valve 6.
[0049] It should be noted that, without limiting to those
positions, the pressure sensor 20a, the pressure sensor 20b, and
the pressure sensor 20c may be located at any positions as long as
the pressure of the refrigerant that flows out of the first
compressor 1, the pressure of the refrigerant that flows into the
expander 3, and the pressure of the refrigerant that flows out of
the on-off valve 6 may be measured, respectively.
[0050] Further, each of the pressure sensor 20a, the pressure
sensor 20b, and the pressure sensor 20c may be a temperature sensor
for measuring a temperature of the refrigerant as long as the
pressure may be estimated.
[0051] The pressure sensor 20a, the pressure sensor 20b, and the
pressure sensor 20c are connected to a controller 21. The
controller 21 controls the opening and closing of the on-off valve
6, the bypass valve 18, and the pre-expansion valve 19 based on
values of the pressure of the refrigerant measured by the pressure
sensor 20a, the pressure sensor 20b, and the pressure sensor
20c.
[0052] The controller 21 includes judging means (not shown) for
judging, after the on-off valve 6 is fully opened, whether or not
the expander 3 is started up, storage means (not shown) for storing
the number of times it is judged that the expander 3 is not started
up, and display means (not shown) for displaying, when the number
of times stored in the storage means has reached a predetermined
number of times, a notification that the expander 3 has failed.
[0053] The first compressor 1, the outdoor heat exchanger 2, the
expander 3, the drive shaft 5, the on-off valve 6, the switch 7a,
the switch 7b, the switch 7c, the second compressor 9, the switch
10a, the switch 10b, the first foreign particle trap 11, the second
foreign particle trap 12, the accumulator 13, the first four-way
valve 14, the check valve 15, the second four-way valve 16, the
bypass circuit 17, the bypass valve 18, the pre-expansion valve 19,
the pressure sensor 20a, the pressure sensor 20b, the pressure
sensor 20c, and the controller 21 constitute an outdoor unit
22.
[0054] The first indoor heat exchanger portion 4a and the indoor
expansion valve 8a constitute an indoor unit 23a, and the second
indoor heat exchanger portion 4b and the indoor expansion valve 8b
constitute an indoor unit 23b.
[0055] The outdoor unit 22 is connected to one end of each of a
liquid main pipe 24 and a gas main pipe 25, the other end of the
liquid main pipe 24 is connected to one end of each of a liquid
branch pipe 26a and a liquid branch pipe 26b, and the other end of
the gas main pipe 25 is connected to one end of each of a gas
branch pipe 27a and a gas branch pipe 27b.
[0056] The other end of the liquid branch pipe 26a is connected to
the indoor expansion valve 8a, and the other end of the liquid
branch pipe 26b is connected to the indoor expansion valve 8b.
[0057] The other end of the gas branch pipe 27a is connected to the
first indoor heat exchanger portion 4a, and the other end of the
gas branch pipe 27b is connected to the second indoor heat
exchanger portion 4b.
[0058] The first compressor 1 is connected to a motor (not shown).
The first compressor 1 is driven by the motor to operate.
[0059] The expander 3 and the second compressor 9 are of a positive
displacement type, specifically, a scroll type.
[0060] It should be noted that, without limiting to the scroll
type, the expander 3 and the second compressor 9 may be of any
other positive displacement type.
[0061] The expander 3 and the second compressor 9 do not have a
motor that generates heat.
[0062] Further, the expander 3 and the second compressor 9 have
substantially equal bearing loads, and hence the expander 3 and the
second compressor 9 cause small loss.
[0063] Therefore, there is no need to use the refrigerant to cool
inside the expander 3 and the second compressor 9, and hence
decrease of refrigerator oil that occurs when the refrigerant cools
the expander 3 and the second compressor 9 may be suppressed.
[0064] As a result, reliability of the expander 3 and the second
compressor 9 may be increased.
[0065] Further, reduction in heat transfer performance of the heat
exchanger due to the decrease of the refrigerator oil may be
suppressed.
[0066] The first outdoor heat exchanger portion 2a and the second
outdoor heat exchanger portion 2b may be connected via the channel
of the refrigerant in series in the cooling operation to improve
the heat transfer performance for radiating heat, and in parallel
in the heating operation to reduce the pressure loss.
[0067] Next, operation of the air conditioner according to this
embodiment is described.
[0068] In the cooling operation, the refrigerant of low pressure
first flows into the first compressor 1 and is compressed to become
high in temperature and medium in pressure.
[0069] After flowing out of the first compressor 1, the refrigerant
passes through the switch 10a and flows into the first outdoor heat
exchanger portion 2a of the outdoor heat exchanger 2.
[0070] After radiating heat to transfer the heat to outdoor air in
the first outdoor heat exchanger portion 2a, the refrigerant
becomes low in temperature and medium in pressure.
[0071] After flowing out of the first outdoor heat exchanger
portion 2a, the refrigerant flows into the second compressor 9 and
is compressed to become high in temperature and high in
pressure.
[0072] After flowing out of the second compressor 9, the
refrigerant passes through the first four-way valve 14 and flows
into the second outdoor heat exchanger portion 2b, in which the
refrigerant radiates heat to transfer the heat to outdoor air and
become low in temperature and high in pressure.
[0073] After flowing out of the second outdoor heat exchanger
portion 2b, the refrigerant is branched to a path that leads to the
second four-way valve 16 and a path that leads to the bypass valve
18.
[0074] The refrigerant that has passed through the second four-way
valve 16 passes through the pre-expansion valve 19 and the first
foreign particle trap 11, flows into the expander 3, and is
decompressed to become low in pressure and take on a state of low
dryness.
[0075] At this time, power is generated in the expander 3 upon the
decompression of the refrigerant. The power is recovered by the
drive shaft 5 and transferred to the second compressor 9 to be used
by the second compressor 9 to compress the refrigerant.
[0076] After flowing out of the expander 3, the refrigerant passes
through the on-off valve 6 and the second four-way valve 16, and
then joins the refrigerant that has been directed to the bypass
valve 18 and has passed through the bypass circuit 17. The
refrigerant flows out of the outdoor unit 22, passes through the
liquid main pipe 24 and then the liquid branch pipe 26a and the
liquid branch pipe 26b, and flows into the indoor unit 23a and the
indoor unit 23b, in which the refrigerant flows into the indoor
expansion valve 8a and the indoor expansion valve 8b.
[0077] In the indoor expansion valve 8a and the indoor expansion
valve 8b, the refrigerant is further decompressed.
[0078] After flowing out of the indoor expansion valve 8a and the
indoor expansion valve 8b, the refrigerant absorbs heat from indoor
air and is evaporated in the first indoor heat exchanger portion 4a
and the second indoor heat exchanger portion 4b to take on a state
of high dryness while maintaining low pressure.
[0079] This way, indoor air is cooled.
[0080] After flowing out of the first indoor heat exchanger portion
4a and the second indoor heat exchanger portion 4b, the refrigerant
flows out of the indoor unit 23a and the indoor unit 23b, passes
through the gas branch pipe 27a and the gas branch pipe 27b and
then the gas main pipe 25, and flows into the outdoor unit 22, in
which the refrigerant passes through the first four-way valve 14
and flows into the accumulator 13 and again into the first
compressor 1.
[0081] The above-mentioned operation is repeated to transfer heat
of indoor air to outdoor air and thereby cool the room.
[0082] In the heating operation, the refrigerant of low pressure
first flows into the first compressor 1 and is compressed to become
high in temperature and high in pressure.
[0083] After flowing out of the first compressor 1, the refrigerant
passes through the switch 7c, the check valve 15, and the first
four-way valve 14.
[0084] At this time, part of the refrigerant, which has passed
through the switch 7c, passes through the second compressor 9 and
then joins the refrigerant that has passed through the check valve
15 to flow into the first four-way valve 14.
[0085] After passing through the first four-way valve 14, the
refrigerant flows out of the outdoor unit 22, passes through the
gas main pipe 25 and then the gas branch pipe 27a and the gas
branch pipe 27b, and flows into the indoor unit 23a and the indoor
unit 23b, in which the refrigerant flows into the first indoor heat
exchanger portion 4a and the second indoor heat exchanger portion
4b of the indoor heat exchanger 4. In the first indoor heat
exchanger portion 4a and the second indoor heat exchanger portion
4b, the refrigerant radiates heat to transfer the heat to indoor
air to become low in temperature and high in pressure.
[0086] After flowing out of the first indoor heat exchanger portion
4a and the second indoor heat exchanger portion 4b, the refrigerant
is decompressed in the indoor expansion valve 8a and the indoor
expansion valve 8b.
[0087] After flowing out of the indoor expansion valve 8a and the
indoor expansion valve 8b, the refrigerant flows out of the indoor
unit 23a and the indoor unit 23b, passes through the liquid branch
pipe 26a and the liquid branch pipe 26b and then the liquid main
pipe 24, flows into the outdoor unit 22, and is branched to a path
that leads to the second four-way valve 16 and a path that leads to
the bypass valve 18.
[0088] The refrigerant that has passed through the second four-way
valve 16 passes through the pre-expansion valve 19 and the first
foreign particle trap 11, flows into the expander 3, and is
decompressed to become low in pressure and take on the state of low
dryness.
[0089] At this time, power is generated in the expander 3 upon the
decompression of the refrigerant. The power is recovered by the
drive shaft 5, transferred to the second compressor 9, and used by
the second compressor 9 to compress the refrigerant.
[0090] After flowing out of the expander 3, the refrigerant passes
through the on-off valve 6 and the second four-way valve 16, and
then joins the refrigerant that has been directed to the bypass
valve 18 and has passed the bypass circuit 17. The refrigerant is
branched again to flow into the first outdoor heat exchanger
portion 2a and the second outdoor heat exchanger portion 2b.
[0091] In the first outdoor heat exchanger portion 2a and the
second outdoor heat exchanger portion 2b, the refrigerant absorbs
heat from outdoor air and is evaporated to take on a state of high
dryness while maintaining low pressure.
[0092] After flowing out of the first outdoor heat exchanger
portion 2a and the second outdoor heat exchanger portion 2b, the
refrigerant joins again, passes through the first four-way valve
14, and flows into the accumulator 13 and again into the first
compressor 1.
[0093] The above-mentioned operation is repeated to transfer heat
of outdoor air to indoor air and thereby heat the room.
[0094] The air conditioner is used as a multi-system air
conditioner for a building and adapted to increase an operation
efficiency in a mild cooling season in which a cooling load is not
large in order to increase an annual operation efficiency.
[0095] Therefore, the expander 3, the second compressor 9, the
outdoor heat exchanger 2, and the indoor heat exchanger 4 are
designed to be best for the mild cooling season. In the heating
operation, it is more advantageous in control for the refrigerant
not to pass through the expander 3 and the second compressor 9.
[0096] However, when the refrigerant does not pass through the
expander 3 and the second compressor 9 in the heating operation,
the refrigerant dwells in the expander 3 and the second compressor
9. As a result, when the expander 3 and the second compressor 9 are
started up, the expander 3 and the second compressor 9 may be
damaged due to poor lubrication.
[0097] Therefore, the refrigerant is allowed to pass through the
expander 3 and the second compressor 9 also in the heating
operation.
[0098] It should be noted that the second compressor 9 operates to
such an extent as not to compress the refrigerant.
[0099] Next, power to be transferred from the expander 3 to the
second compressor 9 of the air conditioner according to this
embodiment is described.
[0100] FIG. 3(a) is a schematic diagram illustrating a breakdown of
the power transferred from the expander 3 to the second compressor
9 in a steady state, and FIG. 3(b) is a schematic diagram
illustrating a breakdown of the power transferred from the expander
3 to the second compressor 9 during activation.
[0101] Both in the steady state and during the activation, the
power to be ultimately recovered is power obtained by subtracting
the loss caused by the expander 3 and the loss caused by the second
compressor 9 from the power received by the expander 3 from the
dynamic pressure of the refrigerant.
[0102] However, in comparison to the steady state, the loss
generated by the expander 3 and the loss generated by the second
compressor 9 become larger during the activation, and hence less
power is ultimately recovered.
[0103] This is because, soon after the activation of the expander 3
when the number of rotations is equal to or less than a
predetermined number of rotations, a friction coefficient of the
bearing is increased to increase the friction loss.
[0104] Further, when the expander 3 is in an inactive state, static
friction larger than dynamic friction occurs in bearings of the
expander 3 and the second compressor 9 to further increase the loss
caused by the expander 3 and the loss caused by the second
compressor 9.
[0105] Further, when the air conditioner has been in an inactive
state for a long time, the refrigerator oil in the expander 3 and
the second compressor 9 is increased in viscosity due to low
temperature. When the air conditioner is to be started up to start
up the expander 3 from this state, the loss caused by the expander
3 and the loss caused by the second compressor 9 are further
increased.
[0106] Further, soon after the air conditioner is manufactured and
shipped, the operation time is too short for slide members of the
expander 3 and the second compressor 9 to fit well, to thereby
cause large friction and further increase the loss caused by the
expander 3 and the loss caused by the second compressor 9.
[0107] Next, operation of the expander 3 during the activation,
that is, soon after the on-off valve 6 is fully opened from a fully
closed state, is described.
[0108] FIG. 4(a) is a diagram illustrating the pressure of the
refrigerant, a volume of the refrigerant, and a mass of the
refrigerant in the steady state of the expander 3, and FIG. 4(b) is
a diagram illustrating the pressure of the refrigerant, the volume
of the refrigerant, and the mass of the refrigerant during the
activation of the expander 3.
[0109] In the steady state, the pressure of the refrigerant in the
expansion chamber of the expander 3 is equal to an inlet pressure
that is the pressure at the inlet of the refrigerant of the
expander 3 at a start point of an expansion process, decreases in
the course of the expansion process from the start point to an end
point of the expansion process, and becomes equal to an outlet
pressure that is the pressure at an outlet of the refrigerant of
the expander 3 at the end point of the expansion process.
[0110] The volume of the refrigerant in the expansion chamber of
the expander 3 increases from the start point to the end point of
the expansion process.
[0111] The mass of the refrigerant in the expansion chamber of the
expander 3 does not change between the start point and the end
point of the expansion process.
[0112] In contrast, during the activation, that is, soon after the
on-off valve 6 is fully opened from the fully closed state, the
pressure of the refrigerant in the expansion chamber of the
expander 3 does not change between the start point and the end
point of the expansion process. On the downstream side of the end
point, the pressure changes discontinuously to be decreased and
become equal to the pressure of the refrigerant measured by the
pressure sensor 20c.
[0113] The volume of the refrigerant in the expansion chamber of
the expander 3 increases as in the steady state from the start
point to the end point of the expansion process.
[0114] The mass of the refrigerant in the expansion chamber of the
expander 3 increases from the start point to the end point of the
expansion process.
[0115] Therefore, the circulating volume of the refrigerant during
the period in which the expander 3 is started up and the expander 3
is rotated once is larger than the circulating volume of the
refrigerant in the steady state to give larger rotation power.
[0116] Further, the interface area between the expansion chamber
and space after the expansion process is large before and after the
endpoint of the expansion process, and a pressure difference
between before and after the end point of the expansion process is
larger than the pressure difference in the steady state soon after
the on-off valve 6 is fully opened from the fully closed state, to
thereby give large recovered power that is determined by the area
and the pressure.
[0117] As described above, soon after the on-off valve 6 is fully
opened from the fully closed state, the expander 3 may obtain the
large recovered power.
[0118] Therefore, even when the loss caused by the expander 3 and
the loss caused by the second compressor 9 are large, the expander
3 may be started up.
[0119] Further, the on-off valve 6 is fully closed from when the
first compressor 1 is started up until when the pressure of the
refrigerant in the expander 3 becomes a critical pressure or
higher, and hence the high-pressure refrigerant reduces the
viscosity of the refrigerator oil in the expander 3 and the second
compressor 9.
[0120] This way, the loss caused by the expander 3 and the loss
caused by the second compressor 9 soon after the on-off valve 6 is
fully opened may be decreased, and hence the expander 3 may obtain
the large recovered power.
[0121] Next, start-up operation of the air conditioner according to
this embodiment is described.
[0122] FIG. 5 is a flow chart illustrating the start-up operation
of the air conditioner of FIGS. 1 and 2.
[0123] When the air conditioner is started up (Step S1), it is
judged which of cooling operation and heating operation the
requested operation is (Step S2).
[0124] When it is judged in Step S2 that the heating operation is
requested, the heating operation is started (Step S3).
[0125] On the other hand, when it is judged in Step S2 that the
cooling operation is requested, the cooling operation is started
(Step S4).
[0126] When the cooling operation is started, a first cooling
circuit is set, in which the switch 7a, the switch 7b, and the
switch 7c are closed, the switch 10a and the switch 10b are opened,
valves in the first four-way valve 14 are switched so that the
refrigerant is allowed to flow from the second compressor 9 to the
second outdoor heat exchanger portion 2b and the refrigerant is
allowed to flow from the indoor heat exchanger 4 to the accumulator
13, and valves in the second four-way valve 16 are switched so that
the refrigerant is allowed to flow from the second outdoor heat
exchanger portion 2b through the expander 3 to the indoor heat
exchanger 4 (Step S5).
[0127] Then, the on-off valve 6 is fully closed and the
pre-expansion valve 19 is fully opened (Step S6), and other devices
are put into a first initial cooling setting that is an initial
state of the cooling operation (Step S7) so that the air
conditioner enters a first start-up mode (Step S8).
[0128] When the air conditioner enters the first start-up mode,
first, the first compressor 1 is started up (Step S9), the pressure
sensor 20b measures the pressure of the refrigerant at the inlet of
the expander 3, the pressure sensor 20c measures the pressure of
the refrigerant at the outlet of the on-off valve 6, and the
controller 21 calculates a difference between the pressure of the
refrigerant at the inlet of the expander 3 and the pressure of the
refrigerant at the outlet of the on-off valve 6 (Step S10).
[0129] Then, the controller 21 judges whether a predetermined
period Ta has elapsed since the first compressor 1 is started up
(Step S11).
[0130] The predetermined period Ta is preset in a range of from 10
seconds to 60 seconds.
[0131] It should be noted that the predetermined period Ta is not
limited to the time range.
[0132] When the controller 21 judges in Step S11 that the
predetermined period Ta has not elapsed since the first compressor
1 is started up, the process returns to Step S10.
[0133] On the other hand, when the controller 21 judges in Step S11
that the predetermined period Ta has elapsed, it is judged whether
the pressure of the refrigerant at the inlet of the expander 3 is
equal to or higher than the critical pressure and the difference
between the pressure of the refrigerant at the inlet of the
expander 3 and the pressure of the refrigerant at the outlet of the
on-off valve 6 is equal to or larger than a predetermined pressure
Pa (Step S12).
[0134] The predetermined pressure Pa is preset in a range of from
2.5 MPa to 5 MPa.
[0135] When the controller 21 judges in Step S12 that the pressure
of the refrigerant at the inlet of the expander 3 is not equal to
or higher than the critical pressure or that the difference between
the pressure of the refrigerant at the inlet of the expander 3 and
the pressure of the refrigerant at the outlet of the on-off valve 6
is not equal to or larger than the predetermined pressure Pa, a
degree of opening of the bypass valve 18 is reduced (Step S13) and
the process returns to Step S10.
[0136] On the other hand, when the controller 21 judges in Step S12
that the pressure of the refrigerant at the inlet of the expander 3
is equal to or higher than the critical pressure and that the
difference between the pressure of the refrigerant at the inlet of
the expander 3 and the pressure of the refrigerant at the outlet of
the on-off valve 6 is equal to or larger than the predetermined
pressure Pa, the on-off valve 6 is fully opened (Step S14).
[0137] Then, the controller 21 judges whether a predetermined
period Tb has elapsed since the on-off valve 6 is fully opened
(Step S15).
[0138] The predetermined period Tb is shorter than the
predetermined period Ta of Step S11 and preset in a range of from 5
seconds to 30 seconds.
[0139] It should be noted that the predetermined period Tb is not
limited to the time range.
[0140] When the controller 21 judges in Step S15 that the
predetermined period Tb has not elapsed since the on-off valve 6 is
fully opened, Step S15 is repeated.
[0141] On the other hand, when the controller 21 judges in Step S15
that the predetermined period Tb has elapsed, the pressure sensor
20a measures the pressure of the refrigerant at the outlet of the
first compressor 1, the pressure sensor 20b measures the pressure
of the refrigerant at the inlet of the expander 3, and the
controller 21 calculates a difference between the pressure of the
refrigerant at the inlet of the expander 3 and the pressure of the
refrigerant at the outlet of the first compressor 1 (Step S16).
[0142] Then, the controller 21 judges whether the difference
between the pressure of the refrigerant at the inlet of the
expander 3 and the pressure of the refrigerant at the outlet of the
first compressor 1 is equal to or larger than a predetermined
pressure Pb (Step S17).
[0143] The predetermined pressure Pb is preset in a range of from 0
MPa to 0.5 MPa.
[0144] It should be noted that the predetermined pressure Pb is not
limited to the pressure range.
[0145] When the controller 21 judges in Step S17 that the
difference between the pressure of the refrigerant at the inlet of
the expander 3 and the pressure of the refrigerant at the outlet of
the first compressor 1 is equal to or larger than the predetermined
pressure Pb, the judging means judges that the expander 3 has
successfully started up, the air conditioner exits the first
start-up mode, and first steady control in a steady state is
performed (Step S18).
[0146] On the other hand, when the controller 21 judges in Step S17
that the difference between the pressure of the refrigerant at the
inlet of the expander 3 and the pressure of the refrigerant at the
outlet of the first compressor 1 is not equal to or larger than the
predetermined pressure Pb, the judging means judges that the
activation of the expander 3 has failed, and the air conditioner
enters a backup mode (Step S19).
[0147] When the air conditioner enters the backup mode, the storage
means adds one to the number of times the activation failed stored
therein (Step S20), and further judges whether the number of times
the activation failed is the predetermined number of times (Step
S21).
[0148] The predetermined number of times is preset in a range of
from 5 to 10.
[0149] It should be noted that the predetermined number of times is
not limited to the number range.
[0150] When the controller 21 judges in Step S21 that the number of
times the activation failed is less than the predetermined number
of times, the process returns to Step S5.
[0151] On the other hand, when the controller 21 judges in Step S21
that the number of times the activation failed has reached the
predetermined number of times, the expander 3 or the second
compressor 9 is regarded as having failed, and the air conditioner
starts backup control (Step S22).
[0152] In the backup control, first, the first compressor 1 is
stopped (Step S23), the display means of the controller 21 displays
a notification that the expander 3 or the second compressor 9 has
failed (Step S24) to notify the manager or the user of the
failure.
[0153] Then, a second cooling circuit is set so that the
refrigerant does not flow into the expander 3 and the second
compressor 9 (Step S25), in which the on-off valve 6 is fully
closed, the pre-expansion valve 19 is closed, and the bypass valve
18 is opened so that the refrigerant does not pass through the
expander 3 and the second compressor 9, and other actuators are put
into a second initial cooling setting that is a state before
cooling is started (Step S26).
[0154] The air conditioner enters a second start-up mode in which
the expander 3 is not started up (Step S27), and the first
compressor 1 is started up without operating the expander 3 to
perform steady operation in the steady state (Step S28), so that
the cooling operation in which the refrigerant is circulated
continues as illustrated in a refrigerant circuit diagram of FIG.
6.
[0155] In this case, if, for example, the expander 3 or the second
compressor 9 has failed, the refrigerant does not pass through the
expander 3 and the second compressor 9 so as to prevent the first
compressor 1, the indoor expansion valve 8a, the indoor expansion
valve 8b, and the like from being damaged.
[0156] Further, if, for example, the expander 3 or the second
compressor 9 has failed, the cooling operation may be
continued.
[0157] As described above, according to the air conditioner of this
embodiment, even if large power is required to start up the
expander 3, the on-off valve 6 is fully opened after the first
compressor 1 is started up and the pressure of the refrigerant in
the expander 3 is increased, to thereby increase the refrigerant
that passes through the on-off valve 6. As a result, the expander 3
may be started up by the dynamic pressure of the refrigerant.
[0158] Further, even if the refrigerator oil in the expander 3 and
the second compressor 9 is increased in viscosity due to low
temperature, when the pressure of the refrigerant at the inlet of
the expander 3 is equal to or higher than the critical pressure,
the on-off valve 6 is fully opened to allow the refrigerant to pass
through the on-off valve 6. The refrigerant of the critical
pressure or higher acts on the refrigerator oil to decrease the
viscosity of the refrigerator oil. Therefore, the losses caused by
the expander 3 and the second compressor 9 may be decreased.
[0159] Further, when the difference between the pressure of the
refrigerant at the inlet of the refrigerant of the expander 3 and
the pressure of the refrigerant at the outlet thereof is equal to
or larger than the predetermined pressure, the on-off valve 6 is
fully opened to allow the refrigerant to pass through the on-off
valve 6. Therefore, the expander 3 may be started up by the high
dynamic pressure of the refrigerant.
[0160] Further, the air conditioner of this embodiment includes the
judging means for judging whether or not the expander 3 is started
up after the on-off valve 6 is fully opened, the storage means for
storing the number of times the judging means judges that the
expander 3 is not started up, and a display device for displaying a
notification that the expander 3 and the second compressor 9 have
failed when the number of times stored in the storage means has
reached the predetermined number of times. Therefore, the manager
or the user may easily notice that the expander 3 and the second
compressor 9 have failed.
[0161] In the channel of the refrigerant between the outdoor heat
exchanger 2 and the indoor heat exchanger 4, there are provided the
bypass circuit 17 connected in parallel to the expander 3 and the
on-off valve 6 that are connected in series, and the bypass valve
18 for adjusting the flow rate of the refrigerant passing through
the bypass circuit 17. When the number of times stored in the
storage means has reached the predetermined number of times, the
refrigerant passes through the bypass circuit 17. Therefore, when
the expander 3 or the second compressor 9 fails and hence the
expander 3 and the second compressor 9 do not work, the refrigerant
may circulate through the channel of the refrigerant between the
outdoor heat exchanger 2 and the indoor heat exchanger 4.
[0162] Further, the refrigerant movement control means is the
on-off valve 6 that is fully closed to restrict the movement of the
refrigerant from the expander 3 to the indoor heat exchanger 4 in
the cooling operation and is fully opened to control the flow rate
of the refrigerant that moves from the expander 3 to the indoor
heat exchanger 4 in the cooling operation. Therefore, the movement
of the refrigerant from the expander 3 to the indoor heat exchanger
4 may be controlled with a simple configuration.
[0163] Further, in the channel of the refrigerant between the first
compressor 1 and the outdoor heat exchanger 2, there is provided
the second compressor 9, and power is transferred from the expander
3 via the drive shaft 5 to the second compressor 9 in the cooling
operation. Therefore, the power that is generated when the
refrigerant is decompressed by the expander 3 may be used by the
second compressor 9, so that the air conditioner may be increased
in efficiency.
[0164] Further, at the inlet of the refrigerant of the expander 3,
there is provided the first foreign particle trap 11 for trapping
the foreign particles entering the expander 3. The size of the
smallest foreign particles to be trapped by the first foreign
particle trap 11 is smaller than the largest gap in the expansion
chamber of the expander 3. Therefore, the foreign particles may be
prevented from entering the expander 3 and causing the expander 3
to fail.
[0165] Further, at the inlet of the refrigerant of the second
compressor 9, there is provided the second foreign particle trap 12
for trapping the foreign particles entering the second compressor
9. The size of the smallest foreign particles to be trapped by the
second foreign particle trap 12 is smaller than the largest gap in
the compression chamber of the second compressor 9. Therefore, the
foreign particles may be prevented from entering the second
compressor 9 and causing the second compressor 9 to fail.
[0166] The refrigerant is carbon dioxide and hence may reduce ozone
depletion and global warming compared to the conventional
fluorocarbon refrigerant.
[0167] It should be noted that, in this embodiment, the indoor heat
exchanger 4 has been described to include the first indoor heat
exchanger portion 4a and the second indoor heat exchanger portion
4b. However, it should be understood that the present invention is
not limited thereto, and the indoor heat exchanger 4 may include
one indoor heat exchanger portion, or the indoor heat exchanger 4
may include three or more indoor heat exchanger portions.
[0168] Further, the air conditioner has been described to have the
configuration in which the indoor expansion valve 8a is connected
to the first indoor heat exchanger portion 4a and the indoor
expansion valve 8b is connected to the second indoor heat exchanger
portion 4b. However, the air conditioner may have a configuration
in which a single indoor expansion valve is connected to the first
indoor heat exchanger portion 4a and the second indoor heat
exchanger portion 4b, or alternatively, the air conditioner may
have a configuration in which an outdoor expansion valve is
provided to the outdoor unit 22.
[0169] Further, the on-off valve 6 has been described to restrict
the movement of the refrigerant from the expander 3 to the
downstream side when fully closed and to control the flow rate of
the refrigerant moving from the expander 3 to the downstream side
when fully opened. However, it should be understood that the
present invention is not limited thereto, and a flow regulating
valve that is fully closed or nearly fully closed to restrict the
movement of the refrigerant from the expander 3 to the downstream
side and is adjusted in degree of opening to control the flow rate
of the refrigerant moving from the expander 3 to the downstream
side may be used.
[0170] Further, the second compressor 9 has been described to
operate only on the rotation power transferred from the expander 3.
However, it should be understood that the present invention is not
limited thereto, and the second compressor 9 may operate, for
example, on the rotation power transferred from the expander 3 as
well as the rotation power from a motor.
[0171] Further, whether or not to start up the expander 3 has been
judged based on the difference between the pressure of the
refrigerant at the inlet of the refrigerant of the expander 3 and
the pressure of the refrigerant at the outlet of the refrigerant of
the on-off valve 6. However, it should be understood that the
present invention is not limited thereto, and whether or not to
start up the expander 3 may be judged by installing a tachometer or
a vibrometer to the expander 3 and the second compressor 9 or by
measuring the temperature of the refrigerant at the outlet of the
refrigerant of or inside the second compressor 9.
Second Embodiment
[0172] FIG. 7 is a refrigerant circuit diagram of a water heater
according to a second embodiment of the present invention.
[0173] The water heater, which is a refrigerating cycle apparatus
according to this embodiment, includes a compressor 28 for
compressing a refrigerant, a radiator 29 for radiating heat of the
refrigerant compressed by the compressor 28 to heat water, an
expander 30 for decompressing the refrigerant that has passed
through the radiator 29, an evaporator 31 in which the refrigerant
that has passed through the expander 30 absorbs heat and is
evaporated, and a power generator 32 which is connected to the
expander 30 and serves as a power recovery device for recovering
power that is generated when the refrigerant is decompressed by the
expander 30.
[0174] In a channel of the refrigerant between the expander 30 and
the evaporator 31, there is provided an opening regulating valve 33
which serves as refrigerant movement control means that is fully
closed or nearly fully closed to restrict the movement of the
refrigerant from the expander 30 to the evaporator 31 and is
adjusted in degree of opening to control the flow rate of the
refrigerant moving from the expander 30 to the evaporator 31.
[0175] At an inlet of the refrigerant of the compressor 28, there
is provided a pressure sensor 34a for measuring a pressure of the
refrigerant that flows into the compressor 28. At an outlet of the
refrigerant of the compressor 28, there is provided a pressure
sensor 34b for measuring the pressure of the refrigerant that flows
out of the compressor 28.
[0176] The pressure sensor 34a and the pressure sensor 34b are
connected to a controller 35. The controller 35 adjusts the degree
of opening of the opening regulating valve 33 based on values of
the pressure of the refrigerant measured by the pressure sensor 34a
and the pressure sensor 34b.
[0177] The controller 35 includes judging means (not shown) for
judging, after the degree of opening of the opening regulating
valve 33 is increased, whether or not the expander 30 is started
up, and storage means (not shown) for storing the number of times
it is judged that the expander 30 is not started up.
[0178] The refrigerant is made of carbon dioxide.
[0179] The radiator 29 includes water transportation means 36 for
pumping water into the radiator 29 and a hot water supply tank 37
for storing water that has been heated by passing through the
radiator 29.
[0180] The evaporator 31 includes a blower (not shown) for blowing
on the evaporator 31.
[0181] Next, operation of the water heater according to this
embodiment is described.
[0182] First, the refrigerant of low temperature and low pressure
flows into the compressor 28 and is compressed to take on a state
of high temperature and high pressure.
[0183] After flowing out of the compressor 28, the refrigerant
radiates heat in the radiator 29 to take on a state of low
temperature and high pressure.
[0184] At this time, the heat of the refrigerant is transferred to
water via the radiator 29 to heat the water.
[0185] After flowing out of the radiator 29, the refrigerant is
decompressed in the expander 30 to take on a state of low
temperature and low pressure.
[0186] At this time, power that is generated when the refrigerant
is decompressed in the expander 30 is recovered by the power
generator 32.
[0187] The power recovered from the power generator 32 is converted
to electrical energy and used by the compressor 28, the water
transportation means 36, and the blower.
[0188] After flowing out of the expander 30, the refrigerant
absorbs heat in the evaporator 31 and is evaporated to become low
in pressure and change from a state of low dryness to a state of
high dryness.
[0189] At this time, the blower blows on the evaporator 31 so that
the refrigerant in the evaporator 31 may absorb the heat
effectively.
[0190] After flowing out of the evaporator 31, the refrigerant
flows into the compressor 28 again.
[0191] Next, start-up operation of the water heater according to
this embodiment is described.
[0192] FIG. 8 is a flow chart illustrating the start-up operation
of the water heater of FIG. 7.
[0193] When the water heater is started up (Step S101), the opening
regulating valve 33 is switched to a state of being fully opened or
nearly fully opened (Step S102).
[0194] Next, other devices are set to an initial operating state
(Step S103), and the water heater enters a start-up mode to start
up the compressor 28 (Step S104).
[0195] Next, the pressure sensor 34a and the pressure sensor 34b
measure the pressure of the refrigerant at the inlet of the
compressor 28 and the pressure of the refrigerant at the outlet
thereof, respectively, and the controller 35 calculates a
difference between the pressure of the refrigerant at the inlet of
the compressor 28 and the pressure of the refrigerant at the outlet
thereof (Step S105).
[0196] Next, the controller 35 judges whether the difference
between the pressure of the refrigerant at the inlet of the
compressor 28 and the pressure of the refrigerant at the outlet
thereof is equal to or larger than the predetermined pressure (Step
S106).
[0197] When the controller 35 judges in Step S106 that the
difference between the pressure of the refrigerant at the inlet of
the compressor 28 and the pressure of the refrigerant at the outlet
thereof is smaller than the predetermined pressure, the process
returns to Step S105.
[0198] On the other hand, when the controller 35 judges in Step
S106 that the difference between the pressure of the refrigerant at
the inlet of the compressor 28 and the pressure of the refrigerant
at the outlet thereof is equal to or larger than the predetermined
pressure, the degree of opening of the opening regulating valve 33
is increased (Step S107).
[0199] Next, the controller 35 judges whether a predetermined
period has elapsed since the degree of opening of the opening
regulating valve 33 is increased (Step S108).
[0200] When the controller 35 judges in Step S108 that the
predetermined period has not elapsed since the degree of opening of
the opening regulating valve 33 is increased, Step S108 is
repeated.
[0201] On the other hand, when the controller 35 judges in Step
S108 that the predetermined period has elapsed, a voltage of the
power generator 32 is measured (Step S109).
[0202] Then, the controller 35 judges whether the voltage of the
power generator 32 is equal to or higher than a predetermined
voltage (Step S110).
[0203] When the controller 35 judges in Step S110 that the voltage
of the power generator 32 is equal to or higher than the
predetermined voltage, the judging means regards the activation of
the expander 30 as a success, the water heater exits the start-up
mode, and steady control in a steady state is performed (Step
S111).
[0204] On the other hand, when the controller 35 judges in Step
S110 that the voltage of the power generator 32 is lower than the
predetermined voltage, the judging means regards the activation of
the expander 30 as a failure, and the water heater enters a backup
mode (Step S112).
[0205] When the water heater enters the backup mode, the storage
means of the controller 35 adds one to the number of times the
activation failed stored therein, and further judges whether the
number of times the activation failed is equal to or more than a
predetermined number of times.
[0206] When the controller 35 judges that the number of times the
activation failed is less than the predetermined number of times,
the process returns to Step S102.
[0207] On the other hand, when the controller 35 judges that the
number of times the activation failed has reached the predetermined
number of times, the expander 30 or the power generator 32 is
regarded as having failed, and the water heater starts backup
control (Step S113).
[0208] In the backup control, the compressor 28 is stopped.
[0209] As described above, according to the water heater of this
embodiment, the power generator 32 serves as the power recovery
device, and the power recovered by the power generator 32 may be
converted to electrical energy and used by the compressor 28, the
water transportation means 36, and the blower.
[0210] Other effects are the same as those of the first
embodiment.
Third Embodiment
[0211] FIG. 9 is a refrigerant circuit diagram of a water heater
according to a third embodiment of the present invention.
[0212] The water heater according to this embodiment includes a
first compressor 38 for compressing a refrigerant, a radiator 29
for radiating heat of the refrigerant compressed by the first
compressor 38, an expander 30 for decompressing the refrigerant
that has passed through the radiator 29, an evaporator 31 in which
the refrigerant that has passed through the expander 30 absorbs
heat and is evaporated, a drive shaft 39 which is connected to the
expander 30 and serves as a power recovery device for recovering
power that is generated when the refrigerant is decompressed by the
expander 30, and a second compressor 40 which is connected to the
drive shaft 39 and compresses the refrigerant that flows from the
evaporator 31 into the first compressor 38.
[0213] Other configurations are the same as those of the second
embodiment.
[0214] Next, operation of the water heater according to this
embodiment is described.
[0215] The refrigerant of low temperature and low pressure first
flows into the second compressor 40 and is compressed to take on a
state of high temperature and medium pressure.
[0216] After flowing out of the second compressor 40, the
refrigerant flows into the first compressor 38 and is compressed to
take on a state of high temperature and high pressure.
[0217] After flowing out of the first compressor 38, the
refrigerant radiates heat in the radiator 29 to take on a state of
low temperature and high pressure.
[0218] At this time, the heat of the refrigerant is transferred to
water via the radiator 29 to heat the water.
[0219] After flowing out of the radiator 29, the refrigerant is
decompressed in the expander 30 to take on a state of low
temperature and low pressure.
[0220] At this time, power that is generated when the refrigerant
is decompressed in the expander 30 is recovered by the drive shaft
39 and used by the second compressor 40.
[0221] After flowing out of the expander 30, the refrigerant
absorbs heat in the evaporator 31 and is evaporated to become low
in pressure and change from a state of low dryness to a state of
high dryness.
[0222] At this time, the blower blows on the evaporator 31 so that
the refrigerant in the evaporator 31 may absorb the heat
effectively.
[0223] After flowing out of the evaporator 31, the refrigerant
flows into the second compressor 40 again.
[0224] As described above, according to the water heater of this
embodiment, the second compressor 40 is provided in a channel of
the refrigerant between the evaporator 31 and the first compressor
38, and the drive shaft 39 is connected between the expander 30 and
the second compressor 40. Therefore, the power that is generated
when the refrigerant is decompressed in the expander 30 may be used
by the second compressor 40.
[0225] Other effects are the same as those of the first
embodiment.
* * * * *