[0001] The present invention relates to an air conditioning system, more particularly to
an air conditioning system capable of converting waste heat into electricity.
[0002] Referring to Figure 1, a conventional air conditioning system 100 includes an expansion
valve 101, an evaporator 102 coupled to the expansion valve 101, a compressor 103
coupled to the evaporator 102, a condenser 104 coupled between the expansion valve
101 and the compressor 103, two fans 105 respectively disposed adjacent to the evaporator
102 and the condenser 104, and a reservoir 106 disposed between the expansion valve
101 and the condenser 104. The expansion valve 101, the evaporator 102, the compressor
103 and the condenser 104 cooperate to form a coolant circulating loop for circulation
of a coolant. The evaporator 102 is configured to absorb the heat energy from the
air within an interior space, and the coolant flowing therethrough may take the heat
energy from the evaporator 102 to the condenser 104. Then, the condenser 104 is configured
to radiate the heat energy from the coolant to an exterior of the interior space through
a corresponding one of the fans 105.
[0003] However, the heat energy radiated to the exterior will result in the greenhouse effect.
The conventional air conditioning system 100 generates a relatively large amount of
waste heat and radiates the waste heat into the exterior, which is detrimental to
efforts to combat global warming.
[0004] Therefore, an object of the present invention is to provide an air conditioning system
capable of converting waste heat into electricity.
[0005] Accordingly, an air conditioning system of the present invention comprises an air
conditioning unit and an electricity generating unit.
[0006] The air conditioning unit includes an expansion valve, an evaporator coupled to the
expansion valve, a compressor coupled to the evaporator, and a condenser coupled between
the compressor and the expansion valve. The expansion valve, the evaporator, the compressor
and the condenser cooperate to form a first coolant circulating loop for circulation
of a first coolant.
[0007] The electricity generating unit includes a heat radiator disposed adjacent to the
evaporator, a heat absorber coupled to the heat radiator and disposed adjacent to
the condenser, a turbine coupled between the heat radiator and the heat absorber,
and an electricity generator coupled to the turbine. The heat radiator, the heat absorber
and the turbine cooperate to form a second coolant circulating loop for circulation
of a second coolant. The turbine generates mechanical energy from flow of the second
coolant through the turbine. The electricity generator converts the mechanical energy
from the turbine into electricity.
[0008] Other features and advantages of the present invention will become apparent in the
following detailed description of the preferred embodiments with reference to the
accompanying drawings, of which:
Figure 1 is a schematic diagram illustrating a conventional air conditioning system;
Figure 2 is a schematic diagram of a first preferred embodiment of an air conditioning
system capable of converting waste heat into electricity according to this invention;
Figure 3 is a schematic diagram of a second preferred embodiment of an air conditioning
system capable of converting waste heat into electricity according to this invention;
and
Figure 4 illustrates a Stirling engine of the air conditioning system of the second
preferred embodiment.
[0009] Before the present invention is described in greater detail, it should be noted that
like elements are denoted by the same reference numerals throughout the disclosure.
[0010] Referring to Figure 2, the first preferred embodiment of an air conditioning system
of this invention includes an air conditioning unit 1, an electricity generating unit
2, a controller 3, and a battery unit 31.
[0011] The air conditioning unit 1 includes an expansion valve 11, an evaporator 12 coupled
to the expansion valve 11, a compressor 13 coupled to the evaporator 12, and a condenser
14 coupled between the compressor 13 and the expansion valve 11. The expansion valve
11, the evaporator 12, the compressor 13 and the condenser 14 cooperate to form a
first coolant circulating loop for circulation of a first coolant having a relatively
lower boiling point. As an example, the first coolant is carbon dioxide. The air conditioning
unit 1 further includes a fan 15 disposed adjacent to the evaporator 12, and a reservoir
16 disposed between the condenser 14 and the expansion valve 11. The evaporator 12
and the fan 15 are disposed at an air vent of the air conditioning system.
[0012] The electricity generating unit 2 includes a heat radiator 22 disposed adjacent to
the evaporator 12, a coolant pump 23 coupled to the heat radiator 22, a heat absorber
24 coupled to the coolant pump 23 and disposed adjacent to the condenser 14, a turbine
25 coupled between the heat radiator 22 and the heat absorber 24, and an electricity
generator 26 coupled to the turbine 25. The heat radiator 22, the coolant pump 23,
the heat absorber 24 and the turbine 25 cooperate to form a second coolant circulating
loop for circulation of a second coolant having a boiling point higher than the boiling
point of the first coolant. As an example, the second coolant is water or ammonia.
The coolant pump 23 is operable to increase pressure of the second coolant flowing
in the second coolant circulating loop. The turbine 25 is operable to generate mechanical
energy from flow of the second coolant through the turbine 25, and the electricity
generator 26 is operable to convert the mechanical energy from the turbine 25 into
electricity.
[0013] Moreover, the turbine 25 has a turbine shaft and the compressor 13 has a compressor
shaft coupled to the turbine shaft using a first clutch 27, which may be an overrunning
or freewheeling device, such that rotation of the turbine 25 assists in rotation of
the compressor 13 and the electricity generator 26. In this embodiment, the turbine
25 and the electricity generator 26 have a common rotting shaft, so that the turbine
25 rotates to drive the electricity generator 26 to generate electricity. In other
embodiments, the coolant pump 23 may coupled to the electricity generator 26 through
another clutch mechanism.
[0014] In this embodiment, the electricity generating unit 2 further includes a thermoelectric
generator 21 having a cold side 211 disposed for thermal exchange with the first coolant
circulating loop between the evaporator 12 and the compressor 13, and a hot side 212
disposed for thermal exchange with the second coolant circulating loop between the
heat radiator 22 and the turbine 25. The thermoelectric generator 21 is configured
to generate electricity using a temperature difference between the cold side 211 and
the hot side 212.
[0015] The controller 3 is coupled to the battery unit 31, and the thermoelectric generator
21 and the electricity generator 26 of the electricity generating unit 2, and is further
coupled to the compressor 13 and the coolant pump 23. The controller 3 is operable
to control supply of electricity from one of the battery unit 31, the thermoelectric
generator 21 and the electricity generator 26 to the compressor 13 and the coolant
pump 23. In particular, the controller 3 is operable to provide the electricity from
the battery unit 31 to the compressor 13 and the coolant pump 23 during initial operation
of the air conditioning system. Then, the controller 3 is operable to provide the
electricity generated by the electricity generator 26 to the compressor 13 and the
coolant pump 23 when the electricity generator 26 starts to generate the electricity.
[0016] During operation of the air conditioning system of this embodiment, the first coolant
flowing in the first coolant circulating loop of the air conditioning unit 1 is in
a high-pressure liquid state and a temperature thereof is 35°C before the first coolant
flows through the expansion valve 11. The first coolant changes to a low-pressure
spray state and the temperature thereof drops to -10°C after the first coolant flows
through the expansion valve 11. Then, the evaporator 12 is configured for thermal
exchange between the first coolant flowing therethrough and the air through the fan
15 so as to absorb heat energy of the air, such that the first coolant evaporates
to a low-pressure gaseous state and the temperature thereof rises to -5°C. The temperature
of the first coolant rises to 5°C after the first coolant flows along the cold side
211 of the thermoelectric generator 21, and then the compressor 13 is operable to
increase pressure of the first coolant such that the first coolant becomes to a high-pressure
state and the temperature thereof rises to 125°C. Subsequently, the heat energy radiates
from the first coolant through the condenser 14. Thus, the first coolant condenses
into the high-pressure liquid state flowing to the expansion valve 11, and the temperature
thereof drops to 35°C.
[0017] Regarding the second coolant circulating loop of the electricity generating unit
2, the second coolant is in a medium-pressure spray state and a temperature thereof
is 60°C before flowing along the hot side 212 of the thermoelectric generator 21.
Then, the second coolant flows along the hot side 212 resulting in the temperature
difference between the cold side 211 and the hot side 212 of the thermoelectric generator
21 for generating electricity, and the temperature of the second coolant drops to
50°C. The heat radiator 22 is configured for thermal exchange with the evaporator
12 and for radiation of heat energy from the second coolant flowing through the heat
radiator 22 to the first coolant flowing through the evaporator 12, such that the
second coolant condenses to a medium-pressure liquid state and the temperature thereof
drops to 30°C.
[0018] The second coolant changes to a high-pressure liquid state after flowing through
the coolant pump 23, and flows to the heat absorber 24 for absorbing the heat energy
from the first coolant flowing through the condenser 14 such that the second coolant
evaporates to a high-pressure gaseous state and the temperature thereof rises to 120°C.
In this embodiment, since the condenser 14 and the heat absorber 24 are disposed closely
adjacent to each other, the first coolant flowing in the condenser 14 directly exchanges
the heat energy with the second coolant flowing in the heat absorber 24 without additional
medium. Thus, the efficiency of the thermal exchange therebetween is relatively greater.
[0019] The second coolant at the high-pressure gaseous state flows through the turbine 25
such that the turbine 25 generates the mechanical energy from flow of the high-pressure
second coolant, and the temperature of the second coolant drops to 60°C after flowing
through the turbine 25. Accordingly, the electricity generator 26 operates to convert
the mechanical energy from the turbine 25 into electricity provided to the compressor
13 through the controller 3. Further, the rotation of the turbine 25 also assists
in the rotation of the compressor 13 through the first clutch 27 when a rotation speed
of the turbine shaft of the turbine 25 is faster than a rotation speed of the compressor
shaft of the compressor 13.
[0020] In this embodiment, a coefficient of performance (COP) of the air conditioning unit
1 is relatively greater when ambient temperature is relatively higher. By virtue of
the heat radiator 22 of the electricity generating unit 2 disposed adjacent to the
evaporator 12 of the air conditioning unit 1, the COP of the air conditioning unit
1 is certainly increased to 4.5, that is to say, the air conditioning unit 1 can generate
45 kilowatts of heat energy when 10 kilowatts of electricity is provided to the compressor
13. The heat absorber 24, the turbine 25 and the electricity generator 26 of the electricity
generating unit 2 cooperate to convert 20% to 30% of waste heat into electricity,
i.e., approximately 9 to 13.5 kilowatts of electricity. Moreover, the thermoelectric
generator 21 can generate approximately 1 to 2 kilowatts of electricity.
[0021] Referring to Figures 3 and 4, the second preferred embodiment of an air conditioning
system of this invention is shown to be similar to the first preferred embodiment.
In the second preferred embodiment, the electricity generating unit 2 includes a heat
engine 28 and an auxiliary electricity generator 29 that replace the thermoelectric
generator 26 of the first preferred embodiment. The heat engine 28 is capable of converting
heat energy to mechanical work, and the auxiliary electricity generator 29 is coupled
to the heat engine 28 for converting the mechanical work from the heat engine 28 into
electricity. In this embodiment, the heat engine 28 is a Stirling engine, and has
a cold side 281 disposed for thermal exchange with the first coolant circulating loop
between the evaporator 12 and the compressor 13, and a hot side 282 disposed for thermal
exchange with the second coolant circulating loop between the heat radiator 22 and
the turbine 25. The first coolant circulating loop has a first meandering segment
10 disposed for thermal exchange with the cold side 281 of the heat engine 28, and
the second coolant circulating loop has a second meandering segment 20 disposed for
thermal exchange with the hot side 282 of the heat engine 28.
[0022] In summary, the second coolant circulating loop of the electricity generating unit
2 is configured for thermal exchange with the first coolant circulating loop of the
air conditioning unit 1 between the cold side 211 and the hot side 212 of the thermoelectric
generator 21, between the cold side 281 and the hot side 282 of the heat engine 28,
between the heat radiator 22 and the evaporator 12, and between the heat absorber
24 and the condenser 14. The thermoelectric generator 21 and the heat engine 28 generate
electricity via the temperature difference. The heat radiator 22 and the heat absorber
24 cooperate to absorb the waste heat from the air conditioning unit 1, and the waste
heat is converted into electricity through the turbine 25 and the electricity generator
26. Thus, the electricity generating unit 2 is operable to effectively convert the
waste heat from the air conditioning unit 1 into electricity.
[0023] By virtue of the heat radiator 22 disposed adjacent to the evaporator 12, the COP
of the air conditioning unit 1 is certainly increased and is relatively greater with
the relatively higher ambient temperature. Further, by virtue of the controller 3,
the electricity generated by the thermoelectric generator 21, the electricity generator
26 and the heat engine 28 is provided to the compressor 13 and the coolant pump 23.
Accordingly, the electricity consumption of the air conditioning system of this invention
is relatively lower. Additionally, the remainder of the electricity can be outputted
for other use.
1. An air conditioning system
characterized by:
an air conditioning unit (1) including an expansion valve (11), an evaporator (12)
coupled to said expansion valve (11), a compressor (13) coupled to said evaporator
(12), and a condenser (14) coupled between said compressor (13) and said expansion
valve (11), wherein said expansion valve (11), said evaporator (12), said compressor
(13) and said condenser (14) cooperate to form a first coolant circulating loop for
circulation of a first coolant; and
an electricity generating unit (2) including a heat radiator (22) disposed adjacent
to said evaporator (12), a heat absorber (24) coupled to said heat radiator (22) and
disposed adjacent to said condenser (14), a turbine (25) coupled between said heat
radiator (22) and said heat absorber (24), and an electricity generator (26) coupled
to said turbine (25), wherein said heat radiator (22), said heat absorber (24) and
said turbine (25) cooperate to form a second coolant circulating loop for circulation
of a second coolant, said turbine (25) generating mechanical energy from flow of the
second coolant through said turbine (25), said electricity generator (26) converting
the mechanical energy from said turbine (25) into electricity.
2. The air conditioning system as claimed in Claim 1, characterized in that said electricity generating unit (2) further includes a thermoelectric generator
(21) having a cold side (211) disposed for thermal exchange with said first coolant
circulating loop between said evaporator (12) and said compressor (13), and a hot
side (212) disposed for thermal exchange with said second coolant circulating loop
between saidheat radiator (22) and said turbine (25).
3. The air conditioning system as claimed in Claim 2, characterized in that said electricity generating unit (2) further includes a coolant pump (23) disposed
on said second coolant circulating loop between said heat radiator (22) and said heat
absorber (24) for increasing pressure of the second coolant flowing in said second
coolant circulating loop.
4. The air conditioning system as claimed in Claim 3, further characterized by a battery unit (31), and a controller (3) that is coupled to said battery unit (31)
and said electricity generating unit (2), and that is further coupled to at least
one of said compressor (13) and said coolant pump (23), said controller (3) controlling
supply of electricity from one of said battery unit (31) and said electricity generating
unit (2) to said at least one of said compressor (13) and said coolant pump (23).
5. The air conditioning system as claimed in any one of Claims 1 to 4, further characterized by a clutch (27), saidturbine (25) having a turbine shaft, saidcompressor (13) having
a compressor shaft coupled to said turbine shaft using said clutch (27).
6. The air conditioning system as claimed in any one of Claims 1 to 5, characterized in that a boiling point of the first coolant is lower than a boiling point of the second
coolant.
7. The air conditioning system as claimed in any one of Claims 1 to 6, characterized in that the first coolant is carbon dioxide, and the second coolant is water or ammonia.
8. The air conditioning system as claimed in any one of Claims 1 to 7, characterized in that said electricity generating unit (2) further includes a heat engine (28) capable
of converting heat energy to mechanical work and an auxiliary electricity generator
(29) coupled to said heat engine (28) for converting the mechanical work from said
heat engine (28) into electricity, said heat engine (28) having a cold side (281)
disposed for thermal exchange with said first coolant circulating loop between said
evaporator (12) and said compressor (13), and a hot side (282) disposed for thermal
exchange with said second coolant circulating loop between said heat radiator (22)
and said turbine (25).
9. The air conditioning system as claimed in Claim 8, characterized in that said first coolant circulating loop has a first meandering segment (10) disposed
for thermal exchange with said cold side (281) of said heat engine (28), and said
second coolant circulating loop has a second meandering segment (20) disposed for
thermal exchange with said hot side (282) of said heat engine (28).
10. The air conditioning system as claimed in Claim 8, characterized in that said heat engine (28) is a Stirling engine.