U.S. patent application number 11/412137 was filed with the patent office on 2006-11-02 for cogeneration system.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Se Dong Chang, Eun Jun Cho, Baik Young Chung, Sim Bok Ha, Cheol Min Kim.
Application Number | 20060242977 11/412137 |
Document ID | / |
Family ID | 36860097 |
Filed Date | 2006-11-02 |
United States Patent
Application |
20060242977 |
Kind Code |
A1 |
Cho; Eun Jun ; et
al. |
November 2, 2006 |
Cogeneration system
Abstract
A cogeneration system according to the present invention
includes a waste heat supply heat exchanger that supplies waste
heat, which is recovered from an engine, to a suction unit side of
a compressor. Accordingly, the present invention is advantageous in
that it can maximize the use efficiency of the waste heat.
Furthermore, a low compression inverter type compressor having a
compression ratio of 1.5 to 2.5, which is lower than that of the
related art, is used. Therefore, the present invention is
advantageous in that it can maximize the efficiency of the system
since the waste heat supplied from the waste heat supply heat
exchanger can be utilized to a greater extent. The present
invention is also advantageous in that it can prevent damage to the
compressor and can save consumption power since a difference in
pressure between the suction and discharge units of the compressor
becomes small.
Inventors: |
Cho; Eun Jun; (Buchun-si,
KR) ; Ha; Sim Bok; (Kwangmyung-si, KR) ;
Chung; Baik Young; (Inchun-si, KR) ; Kim; Cheol
Min; (Seoul, KR) ; Chang; Se Dong;
(Kwangmyung-si, KR) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN, P.L.C.
1950 ROLAND CLARKE PLACE
RESTON
VA
20191
US
|
Assignee: |
LG Electronics Inc.
|
Family ID: |
36860097 |
Appl. No.: |
11/412137 |
Filed: |
April 27, 2006 |
Current U.S.
Class: |
62/238.7 ;
62/323.1; 62/324.1 |
Current CPC
Class: |
Y02P 80/15 20151101;
F25B 27/00 20130101; F25B 13/00 20130101; F25B 2600/021 20130101;
F25B 2313/0253 20130101; Y02E 20/14 20130101; Y02B 30/70
20130101 |
Class at
Publication: |
062/238.7 ;
062/323.1; 062/324.1 |
International
Class: |
F25B 27/00 20060101
F25B027/00; F25B 13/00 20060101 F25B013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2005 |
KR |
2005-35511 |
Claims
1. A cogeneration system comprising: a generator that generates
electric power; a driving source that drives the generator and
generates heat; waste heat recovery means that recovers waste heat
of the driving source; an air conditioner including a compressor, a
4-way valve, indoor heat exchangers, expansion valves and an
outdoor heat exchanger; and a waste heat supply heat exchanger for
supplying the heat, which is recovered from the waste heat recovery
means, to a suction unit side of the compressor, wherein the
compressor has a compression ratio of 1.5 to 2.5.
2. The cogeneration system as claimed in claim 1, wherein the
compressor is a low compression inverter type compressor having a
variable compression ratio.
3. The cogeneration system as claimed in claim 1, wherein the air
conditioner further comprises a high compression constant speed
type compressor having a compression ratio of 3, 4 or 5.
4. The cogeneration system as claimed in claim 1, wherein the air
conditioner further comprises a high compression inverter type
compressor having a compression ratio having a compression ratio of
3 to 5.
5. The cogeneration system as claimed in claim 1, wherein the
cogeneration system further comprises a bypass flow path along
which the refrigerants, which have passed the expansion valves,
bypass the outdoor heat exchangers during the heating operation of
the air conditioner.
6. The cogeneration system as claimed in claim 5, wherein the
outdoor expansion valve for expanding the refrigerants introduced
from an indoor unit side is disposed on the suction unit side of
the bypass flow path, and a third check valve for preventing the
refrigerants, which are sucked into the outdoor heat exchanger,
from flowing backward into the bypass flow path during the air
cooling operation is disposed on the discharge unit side of the
bypass flow path.
7. The cogeneration system as claimed in claim 1, wherein the waste
heat recovery means comprises: exhaust gas heat exchangers for
recovering the heat of an exhaust gas discharged from the driving
source; and a coolant heat exchanger for recovering the heat of the
coolant that has cooled the driving source.
8. The cogeneration system as claimed in claim 7, wherein the
cogeneration system further comprises heat dissipation means for
dissipating the heat, which is recovered from the coolant heat
exchanger and the exhaust gas heat exchangers to the outside during
the air cooling operation of the air conditioner.
9. The cogeneration system as claimed in claim 1, wherein the waste
heat supply heat exchanger is disposed parallel to the outdoor heat
exchanger on a refrigerant circulation flow path along which the
refrigerants that are circulated through the air conditioner are
guided.
10. The cogeneration system as claimed in claim 9, wherein an air
cooling flow path for causing the refrigerants discharged from the
first and second compressors to bypass the waste heat supply heat
exchanger during the air cooling operation is disposed between the
flow paths of inlet and outlet sides of the waste heat supply heat
exchanger.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The present invention relates to a cogeneration system. More
particularly, the present invention relates to a cogeneration
system including a waste heat supply heat exchanger for supplying
waste heat recovered from an engine to a suction unit of a
compressor, wherein the compressor is a low compression inverter
type compressor with a compression ratio of 1.5 to 2.5 whereby the
waste heat supplied from the waste heat supply heat exchanger can
be utilized to a greater extent and the system efficiency can be
maximized accordingly.
[0003] 2. Discussion of Related Art
[0004] In general, a combined heat power plant is also called a
cogeneration system and is a system that produces electric power
and heat at the same time using one energy source.
[0005] FIG. 1 is a view schematically showing the construction of a
cogeneration system in the related art.
[0006] The related art cogeneration system includes a generator 2
that generates electric power, a driving source (hereinafter,
referred to as an "engine") that drives the generator 2 and
generates heat, such as an engine 10, a waste heat recovery
apparatus 20 that recovers waste heat generated from the engine 10,
a heat demand place 30 such as a heat storage tank that utilizes
the waste heat of the waste heat recovery apparatus 20, and so on,
as shown in FIG. 1.
[0007] The electric power generated from the generator 2 is
supplied to a variety of lighting apparatuses, electronic
appliances such as a heat pump type air conditioner 4 and the
like.
[0008] The generator 2 and the engine 10 are disposed within an
engine room, which is separated from the heat demand place 30.
[0009] The heat pump type air conditioner 4 includes a compressor
5, a 4-way valve 6, an indoor heat exchanger 7, an expansion valve
8 and an outdoor heat exchanger 9.
[0010] In the heat pump type air conditioner 4, during the air
cooling operation, the refrigerants compressed in the compressor 5
are circulated through the 4-way valve 6, the outdoor heat
exchanger 9, the expansion valve 8, the indoor heat exchanger 7 and
the 4-way valve 6, sequentially, and then reach the compressor 5.
Therefore, the outdoor heat exchanger 9 serves as a condenser and
the indoor heat exchanger 7 serves as an evaporator, thereby
depriving heat of the indoor air.
[0011] On the other hand, during the heating operation, the
refrigerants compressed in the compressor 5 are circulated through
the 4-way valve 6, the indoor heat exchanger 7, the expansion valve
8, the outdoor heat exchanger 9 and the 4-way valve 6 sequentially,
and then reach the compressor 5. Therefore, the outdoor heat
exchanger 9 serves as the evaporator and the indoor heat exchanger
7 serves as the condenser, thereby heating the indoor air.
[0012] The waste heat recovery apparatus 20 includes an exhaust gas
heat exchanger 22 that deprives heat of an exhaust gas discharged
from the engine 10, and a coolant heat exchanger 24 that deprives
heat of the coolant that has cooled the engine 10.
[0013] The exhaust gas heat exchanger 22 is connected to the heat
demand place 30 through a first heat supply line 23. The exhaust
gas heat exchanger 22 transfers the waste heat, which has been
deprived of the exhaust gas of the engine 10, to the heat demand
place 30 through the first heat supply line 23.
[0014] The coolant heat exchanger 24 is connected to the heat
demand place 30 through a second heat supply line 25. The coolant
heat exchanger 24 transfers heat, which has been deprived of the
coolant that had cooled the engine 10, to the heat demand place 30
through the second heat supply line 25.
[0015] In the related art cogeneration system, however, the waste
heat recovered from the exhaust gas heat exchanger 22 and the
coolant heat exchanger 24 is used only for hot water, etc. such as
in the heat demand place. Therefore, a problem arises because the
system efficiency cannot be maximized.
SUMMARY OF THE INVENTION
[0016] The present invention has been developed in an effort to
provide a cogeneration system in which waste heat recovered from a
driving source is supplied to a compressor suction unit side of an
air conditioner and a compressor with the lowest compression ratio
is used, thus improving the efficiency of the system.
[0017] A cogeneration system according to an embodiment of the
present invention includes a generator that generates electric
power, a driving source that drives the generator and generates
heat, waste heat recovery means that recovers waste heat of the
driving source, an air conditioner including a compressor, a 4-way
valve, indoor heat exchangers, expansion valves and an outdoor heat
exchanger, and a waste heat supply heat exchanger for supplying the
heat, which is recovered from the waste heat recovery means, to a
suction unit side of the compressor. The compressor may have a
compression ratio of 1.5 to 2.5.
[0018] The compressor may be a low compression inverter type
compressor having a variable compression ratio.
[0019] The air conditioner may further include a high compression
constant speed type compressor having a compression ratio of 3, 4
or 5.
[0020] The air conditioner may further include a high compression
inverter type compressor having a compression ratio having a
compression ratio of 3 to 5.
[0021] The cogeneration system may further include a bypass flow
path along which the refrigerants, which have passed the expansion
valves, bypass the outdoor heat exchangers during the heating
operation of the air conditioner.
[0022] The outdoor expansion valve for expanding the refrigerants
introduced from an indoor unit side is disposed on the suction unit
side of the bypass flow path. A third check valve for preventing
the refrigerants, which are sucked into the outdoor heat exchanger,
from flowing backward into the bypass flow path during the air
cooling operation is disposed on the discharge unit side of the
bypass flow path.
[0023] The waste heat recovery means may include exhaust gas heat
exchangers for recovering the heat of an exhaust gas discharged
from the driving source, and a coolant heat exchanger for
recovering the heat of the coolant that has cooled the driving
source.
[0024] The cogeneration system may further include heat dissipation
means for dissipating the heat, which is recovered from the coolant
heat exchanger and the exhaust gas heat exchangers to the outside
during the air cooling operation of the air conditioner.
[0025] The waste heat supply heat exchanger may be disposed
parallel to the outdoor heat exchanger on a refrigerant circulation
flow path along which the refrigerants that are circulated through
the air conditioner are guided.
[0026] An air cooling flow path for causing the refrigerants
discharged from the first and second compressors to bypass the
waste heat supply heat exchanger during the air cooling operation
may be disposed between the flow paths of inlet and outlet sides of
the waste heat supply heat exchanger.
[0027] The cogeneration system according to the present invention
includes a waste heat supply heat exchanger that supplies waste
heat, which is recovered from the engine, to a suction unit side of
a compressor. Accordingly, the present invention is advantageous in
that it can maximize the use efficiency of waste heat.
[0028] Furthermore, the cogeneration system includes a low
compression inverter type compressor having a compression ratio of
1.5 to 2.5, which is lower than that of the related art. Therefore,
the present invention is advantageous in that it can maximize the
efficiency of the cogeneration system since waste heat supplied
from a waste heat supply heat exchanger can be utilized to a
greater extent. The present invention is also advantageous in that
it can prevent damage to the compressor and can save consumption
power since a difference in pressure between suction and discharge
units of the compressor becomes small.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] A more compete appreciation of the invention, and many of
the attendant advantages thereof, will be readily apparent as the
same becomes better understood by reference to the following
detailed description when considered in conjunction with the
accompanying drawings in which like reference symbols indicate the
same or similar components, wherein:
[0030] FIG. 1 is a view schematically showing the construction of a
cogeneration system in the related art;
[0031] FIG. 2 is a view schematically showing a construction when
an air conditioner of a cogeneration system according to the
present invention is in a heating operation;
[0032] FIG. 3 shows a P-h line graph of the air conditioner
according to the present invention; and
[0033] FIG. 4 is a view schematically showing a construction when
an air conditioner of a cogeneration system according to the
present invention is in an air cooling operation.
DETAILED DESCRIPTION OF THE INVENTION
[0034] In the following detailed description, only certain
exemplary embodiments of the present invention have been shown and
described simply by way of illustration. As those skilled in the
art will realize, the described embodiment may be modified in
various different ways, all without departing from the spirit or
scope of the present invention. Accordingly, the drawings and
description are to be regarded as illustrative in nature and not
restrictive. Like reference numerals designate like elements
throughout.
[0035] FIG. 2 is a view schematically showing a construction when
an air conditioner of a cogeneration system according to the
present invention is in a heating operation. FIG. 3 shows a P-h
line graph of the air conditioner according to the present
invention. FIG. 4 is a view schematically showing a construction
when an air conditioner of a cogeneration system according to the
present invention is in an air cooling operation.
[0036] The cogeneration system according to the present invention
includes a generator 51 that generates electric power, a driving
source that drives the generator 51 and generates heat, waste heat
recovery means 60 that recovers waste heat of the driving source,
an air conditioner and a waste heat supply heat exchanger 80, as
shown in FIGS. 2 to 4.
[0037] The air conditioner includes a compressor 70, a 4-way valve
73, indoor heat exchangers 74, expansion valves 77 and outdoor heat
exchangers 75. The waste heat supply heat exchanger 80 is disposed
parallel to the outdoor heat exchangers 75. The waste heat supply
heat exchanger 80 supplies heat, which is recovered from the waste
heat recovery means 60, to a suction unit side of the compressor 70
during the heating operation of the air conditioner.
[0038] The generator 51 may be either an AC generator or a DC
generator. The generator 51 has a rotator connected to an output
shaft of the driving source. Accordingly, when the output shaft of
the driving source is rotated, the generator 51 generates electric
power.
[0039] The driving source may be an engine 52, a fuel cell or the
like. In the present context, it is assumed that the driving source
is the engine 52.
[0040] The engine 52 has a combustion chamber therein. The engine
52 is connected to a fuel pipe 53 that puts a fuel, such as
Liquefied Natural Gas (LNG) or Liquefied Petroleum Gas (LPG), into
the combustion chamber, and an exhaust pipe 54 along which the
exhaust gas discharged from the combustion chamber is guided.
[0041] The waste heat recovery means 60 includes an exhaust gas
heat exchanger that recovers the heat of the exhaust gas discharged
from the engine 52, and a coolant heat exchanger 63 that recovers
the heat of the coolant that has cooled the engine 52.
[0042] In this case, the exhaust gas heat exchanger may have two
first and second exhaust gas heat exchangers 61, 62. The first and
second exhaust gas heat exchangers 61, 62 are connected to the
exhaust pipe 54 of the engine 52.
[0043] A thermal medium circulation flow path 64 along which heat
from any one of the first and second exhaust gas heat exchangers
61, 62 and the coolant heat exchanger 63 is transferred to the
waste heat supply heat exchanger 80 is disposed between the first
and second exhaust gas heat exchangers 61, 62 and the coolant heat
exchanger 63, and the waste heat supply heat exchanger 80.
[0044] That is, the thermal medium circulation flow path 64 causes
a thermal medium, which is heated while it is sequentially
circulated through the coolant heat exchanger 63, the first exhaust
gas heat exchanger 61 and the second exhaust gas heat exchanger 62,
to be introduced into the waste heat supply heat exchanger 80 and
then to be transferred to the coolant heat exchanger 63.
[0045] The thermal medium circulation flow path 64 includes a
thermal medium circulation pump 65 that circulates and pumps the
thermal medium that is circulated through the thermal medium
circulation flow path 64.
[0046] The coolant heat exchanger 63 is connected to the engine 52
by a coolant circulation flow path 66 along which the coolant,
which is heated while cooling the engine 52, is circulated. A
coolant pump 67 that pumps the coolant is disposed on the coolant
circulation flow path 66.
[0047] Meanwhile, the air conditioner includes an outdoor unit (O)
including the compressor 70, the 4-way valve 73 and the outdoor
heat exchangers 75, and an indoor unit (I) including the indoor
heat exchangers 74. The expansion valve includes an indoor
expansion valve 76 disposed in the indoor unit (I), and an outdoor
expansion valve 77 that is disposed in the outdoor unit (O) and is
used only during the heating operation.
[0048] In this case, the outdoor unit (O) and the indoor unit (I)
can be disposed one by one or in plural numbers. In the following
description, it is assumed that the number of the outdoor unit (O)
and the indoor unit (I) is one (1).
[0049] The compressor 70 disposed in the outdoor unit (O) may be
one low compression inverter type compressor with a compression
ratio of 1.5 to 2.5 or a plurality of low compression inverter type
compressors. At least one of the plurality of low compression
inverter type compressors may have a compression ratio of 1.5 to
2.5.
[0050] In the following description, it is assumed that each of the
compressors 70 consists of two first and second compressors 71,
72.
[0051] The first compressor 71 may be a low compression inverter
type compressor having a compression ratio of 1.5 to 2.5. The
second compressor 72 may be a high compression constant speed type
compressor with a compression ratio of 3, 4 or 5.
[0052] The suction units of the first and second compressors 71, 72
are connected by a common use accumulator 78.
[0053] Meanwhile, the waste heat supply heat exchanger 80 is
disposed parallel to the outdoor heat exchangers 75 on a
refrigerant circulation flow path 79 along which the refrigerants
that are circulated through the air conditioner are guided.
[0054] A first opening and shutting valve 81 for preventing the
refrigerants from flowing into the waste heat supply heat exchanger
80 during the air cooling operation is placed on the inlet side of
the waste heat supply heat exchanger 80 on the refrigerant
circulation flow path 79. Furthermore, a first check valve 91 for
preventing the refrigerants from flowing backward into the waste
heat supply heat exchanger 80 during the cooling operation is
placed on the outlet side of the waste heat supply heat exchanger
80 on the refrigerant circulation flow path 79.
[0055] Furthermore, an air cooling flow path 84 for causing the
refrigerants, which are discharged from the first and second
compressors 71, 72, to bypass the waste heat supply heat exchanger
80 during the air cooling operation is disposed between the flow
paths of the inlet side and the outlet side of the waste heat
supply heat exchanger 80.
[0056] The refrigerants flow only during the air cooling operation.
A second opening and shutting valve 82 for shutting the flow of the
refrigerants during the heating operation is disposed on the air
cooling flow path 84.
[0057] The cogeneration system further includes a bypass flow path
90 along which the refrigerants, which have passed the indoor
expansion valves 76, bypass the outdoor heat exchangers 75 during
the heating operation of the air conditioner.
[0058] The bypass flow path 90 has one end connected to an outdoor
heat exchanger suction flow path 85 along which the refrigerants,
which have passed the first and second compressors 71, 72, flow
into the outdoor heat exchangers 75 during the during air cooling
operation and has the other end connected to an outdoor heat
exchanger discharge flow path 86 along which the refrigerants are
discharged from the outdoor heat exchangers 75.
[0059] A third opening and shutting valve 83 for shutting the
outdoor heat exchanger suction flow path 85 during the heating
operation is disposed on the outdoor heat exchanger suction flow
path 85. Furthermore, a second check valve 92 for preventing the
refrigerants, which are introduced from the indoor unit (I), to
flowing into the outdoor heat exchangers 75, is disposed on the
outdoor heat exchanger discharge flow path 86.
[0060] Furthermore, the outdoor expansion valve 77 for expanding
the refrigerants introduced from the indoor unit (I) side is
disposed on the suction unit side of the bypass flow path 90. A
third check valve 93 for preventing the refrigerants, which are
introduced into the outdoor heat exchangers 75, from flowing
backward into the bypass flow path 90 during the air cooling
operation is disposed on the discharge unit side of the bypass flow
path 90.
[0061] The cogeneration system further includes heat dissipation
means for radiating heat, which is recovered from the coolant heat
exchanger 63 and the first and second exhaust gas heat exchangers
61, 62, to the outside during the air cooling operation of the air
conditioner.
[0062] The heat dissipation means includes the coolant heat
exchanger 63, a heat dissipation heat exchanger 68 for radiating
heat, which is recovered from the first and second exhaust gas heat
exchangers 61, 62, into the air, and a heat dissipation flow path
69 connected to the thermal medium circulation flow path 64, for
guiding the thermal medium into the heat dissipation heat exchanger
68.
[0063] A heat dissipation fan for ventilating the outdoor air
toward the heat dissipation heat exchanger 68 is disposed on the
side of the heat dissipation heat exchanger 68.
[0064] A 3-way valve 94 for switching the flow of the thermal
medium depending on the air cooling or heating operation of the air
conditioner is disposed at a portion where the thermal medium
circulation flow path 64 and the heat dissipation flow path 69 are
connected.
[0065] However, the present invention is not limited to the above
embodiment. For example, the compressor 70 may include a low
compression inverter type compressor having a compression ratio of
1.5 to 2.5 and a high compression inverter type compressor having a
compression ratio of 3 to 5.
[0066] The operation of the cogeneration system constructed above
according to the present invention will be described below.
[0067] If the engine 52 is driven, the generator 51 generates
electric power and the generated electric power is supplied to the
air conditioner, etc.
[0068] At this time, when the engine 52 is driven, the exhaust gas
waste heat and the coolant waste heat of the engine 52 are
recovered by the first and second exhaust gas heat exchangers 61,
62 and the coolant heat exchanger 63.
[0069] During the heating operation of the air conditioner, the
thermal medium circulation pump 65 is driven and the 3-way valve 94
switches the flow path so that the thermal medium can be introduced
into the waste heat supply heat exchanger 80, as shown in FIG.
2.
[0070] The thermal medium on the thermal medium circulation flow
path 64 is pumped by the thermal medium circulation pump 65, passes
through the coolant heat exchanger 63, the first exhaust gas heat
exchanger 61 and the second exhaust gas heat exchanger 62
sequentially, and then introduces into the waste heat supply heat
exchanger 80, thereby heating the waste heat supply heat exchanger
80.
[0071] Furthermore, the 4-way valve 73 of the air conditioner is
switched to a heating mode.
[0072] The refrigerants compressed in the first and second
compressors 71, 72 pass through the 4-way valve 73. The
refrigerants are deprived of heat by the indoor air, while passing
through the indoor heat exchangers 74, and are then expanded in the
indoor expansion valves 76.
[0073] The refrigerants expanded in the indoor expansion valves 76
are introduced into the bypass flow path 90.
[0074] At this time, a second check valve 92 disposed on the part
of the outdoor heat exchanger discharge flow path 86 prevents the
refrigerants from flowing intro the outdoor heat exchanger 75.
[0075] Furthermore, during the heating operation of the air
conditioner, the second and third opening and shutting valves 82,
83 are shut and only the first opening and shutting valve 81 is
opened.
[0076] Therefore, the refrigerants introduced into the bypass flow
path 90 are introduced into the waste heat supply heat exchanger 80
through the outdoor expansion valves 77, the third check valve 93
and the first opening and shutting valve 91.
[0077] The refrigerants introduced into the waste heat supply heat
exchanger 80 are evaporated by the heat of the waste heat supply
heat exchanger 80.
[0078] That is, the outdoor heat exchanger 75 is not used, but] the
waste heat supply heat exchanger 80 serves as the evaporator.
[0079] The refrigerants evaporated in the waste heat supply heat
exchanger 80 pass through the first check valve 91 and the 4-way
valve 73 and are then absorbed by the first and second compressors
71, 72 through the common use accumulator 78.
[0080] Therefore, the heat recovered from the coolant heat
exchanger 63 and the first and second exhaust gas heat exchangers
61, 62 is transferred to the suction unit sides of the first and
second compressors 71, 72 of the waste heat supply heat exchanger
80.
[0081] The refrigerants absorbed by the first and second
compressors 71, 72 heat the room while performing the above
circulation. In this case, the refrigerants are evaporated in the
waste heat supply heat exchanger 80 not in the outdoor heat
exchangers 75. Accordingly, the air conditioner can provide a
constant heating capability regardless of variations in an outdoor
temperature.
[0082] Furthermore, since the waste heat of the engine 52 is
supplied to the suction unit sides of the first and second
compressors 71, 72, the condensation pressure can be increased to
enhance the heating capability. Furthermore, since the pressure at
the suction unit sides of the first and second compressors 71, 72
is increased, the first and second compressors 71, 72 can be
prevented from being damaged.
[0083] Meanwhile, when the operation capacity of the air
conditioner is small or an indoor or outdoor temperature is high,
only the first compressor 71 having the low compression inverter
type compressor with a low compression ratio is driven.
[0084] If only the first compressor 71 with a low compression ratio
is driven, a suction pressure (P1) sucked by the first compressor
71, i.e., an evaporation pressure (P'eva=P1) of the refrigerants,
which are supplied from the waste heat supply heat exchanger 80
used as the evaporator to the first compressor 71, becomes higher
than an evaporation pressure (Peva) in the related art in which a
compressor with a high compression ratio is used. Accordingly, an
amount of recovered heat (Q') supplied from the waste heat supply
heat exchanger 80 becomes higher than recovered heat (Q) that can
be supplied in the related art, as shown in FIG. 3.
[0085] In other words, if the first compressor 71 with a low
compression ratio is driven, the recovered heat (Q') supplied from
the waste heat supply heat exchanger 80 can be used to a greater
extent in comparison with the related art.
[0086] Therefore, even when the operation capacity of the air
conditioner is small or an indoor or outdoor temperature is high,
the heat of the waste heat supply heat exchanger 80 can be utilized
to the maximum extent without the need to dissipate some of the
heat. Accordingly, the waste heat use efficiency can be
improved.
[0087] Furthermore, since a difference in pressure between the
suction and discharge units of the first compressor 71 is small,
the the first compressor 71 can be prevented from being damaged and
the efficiency can also be enhanced.
[0088] If the operation capacity of the air conditioner is
increased afterward, the second compressor 72 (i.e., the high
compression constant speed type compressor) is also driven.
[0089] Meanwhile, during the air cooling operation of the air
conditioner, the thermal medium of the thermal medium circulation
flow path 64 is pumped by the thermal medium circulation pump 65
and then has its waste heat recovered while sequentially passing
through the coolant heat exchanger 63, the first exhaust gas heat
exchanger 61 and the second exhaust gas heat exchanger 62, as shown
in FIG. 4.
[0090] At this time, the 3-way valve 94 is switched so that the
thermal medium can be moved to the heat dissipation heat exchanger
68. Therefore, the recovered waste heat is transferred to the heat
dissipation heat exchanger 68 through the heat dissipation flow
path 69 and then discharged into the air.
[0091] Therefore, during the air cooling operation, the waste heat
of the engine 52 is not used to heat the waste heat supply heat
exchanger 80, but is discharged into the air.
[0092] The 4-way valve 73 is then switched to an air cooling mode,
the second and third opening and shutting valves 82, 83 are opened
and the first opening and shutting valve 81 is shut.
[0093] Furthermore, the outdoor expansion valves 77 is turned off
to shut the bypass flow path 90.
[0094] Therefore, the refrigerants compressed in the first and
second compressors 71, 72 pass through the 4-way valve 73, the
outdoor heat exchangers 75, the indoor expansion valves 76 and the
indoor heat exchangers 74 sequentially and are then introduced into
the first and second compressors 71, 72 through the 4-way valve
73.
[0095] At this time, the refrigerants compressed in the first and
second compressors 71, 72 are condensed through the heat exchange
with the outdoor air while passing through the outdoor heat
exchangers 75, expanded through the indoor expansion valves 76, and
exchange heat with the indoor air through the indoor heat
exchangers 74, thereby cooling the room.
[0096] The cogeneration system constructed above according to the
present invention has the following advantages.
[0097] The cogeneration system according to the present invention
includes the waste heat supply heat exchanger that supplies waste
heat, which is recovered from the engine, to the suction unit side
of the compressor. Accordingly, the present invention is
advantageous in that it can maximize the use efficiency of the
waste heat.
[0098] Furthermore, the cogeneration system includes the low
compression inverter type compressor having a compression ratio of
1.5 to 2.5, which is lower than that of the related art. Therefore,
the present invention is advantageous in that it can maximize the
efficiency of the system since the waste heat supplied from the
waste heat supply heat exchanger can be utilized to a greater
extent. The present invention is also advantageous in that it can
prevent damage to the compressor and can save consumption power
since a difference in pressure between the suction and discharge
units of the compressor becomes small.
[0099] While the invention has been described in connection with
what is presently considered to be practical exemplary embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments, but, on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
* * * * *