Patent application title: AIR CONDITIONING APPARATUS
Inventors:
Been-Wei Liaw (Taichung City, TW)
Hau-Chieh Lin (Kaohsiung City, TW)
IPC8 Class: AF24H302FI
USPC Class:
392347
Class name: Electric resistance heating devices heating devices (class 219 subclass 200) convection space heater
Publication date: 2015-12-10
Patent application number: 20150354852
Abstract:
An air conditioning apparatus includes a casing having an inlet and an
outlet, an airflow import device, a nozzle, two valves disposed at two
ends of the nozzle, a vacuum pump connected through the nozzle, a
connecting device, a heater, a humidifier, and an airflow export device.
The airflow import and export devices are disposed at positions near the
inlet and the outlet inside the casing. The nozzle includes an intake
portion, a throat, and an exhaust portion connected sequentially and
coaxially. A cross-sectional area of the intake portion decreases
gradually from one end away from the throat to the other end close to the
throat. A cross-sectional area of the throat is smaller than that of the
exhaust portion. The connecting device is connected to the intake portion
and the exhaust portion. The heater and the humidifier are disposed
between the nozzle and the outlet.Claims:
1. An air conditioning apparatus, comprising: a casing comprising an
inlet and an outlet; an airflow import device disposed in the casing at a
position near the inlet; a supersonic nozzle disposed between the airflow
import device and the outlet and comprising an intake portion, a throat,
and an exhaust portion disposed sequentially and coaxially, wherein a
cross-sectional area of the intake portion decreases gradually from an
end away from the throat to the other end close to the throat, and a
cross-sectional area of the throat is smaller than a cross-sectional area
of the exhaust portion; two valves respectively disposed at an inlet port
of the intake portion and an outlet port of the exhaust portion; a vacuum
pump connected to communicate with the supersonic nozzle; a connecting
device connected with a side wall of the intake portion of the supersonic
nozzle and a side wall of the exhaust portion, wherein the connecting
device and the supersonic nozzle are non-coaxial; a heater and a
humidifier disposed between the supersonic nozzle and the outlet; and an
airflow export device disposed after the heater and the humidifier and in
the casing at a position near the outlet.
2. The air conditioning apparatus according to claim 1, wherein a sequence of the heater and the humidifier comprises one of the following: the heater being disposed before the humidifier and the humidifier being disposed before the heater.
3. The air conditioning apparatus according to claim 2, further comprising: a water collection tank disposed below the exhaust portion in a gravity direction and connected to communicate with the exhaust portion, wherein a pressure in the water collection tank is substantially equal to a pressure in the exhaust portion.
4. The air conditioning apparatus according to claim 3, further comprising: a filter module disposed between the water collection tank and the humidifier, wherein water in the water collection tank is adapted to flow to the humidifier after flowing through the filter module.
5. The air conditioning apparatus according to claim 2, further comprising: a power generation device disposed after the supersonic nozzle and before the heater and the humidifier to generate electricity when air flows by, wherein the power generation device is electrically connected with the heater.
6. The air conditioning apparatus according to claim 2, wherein an inner diameter of the throat is adjustable.
7. The air conditioning apparatus according to claim 2, further comprising: a silencer tube disposed at an end of the exhaust portion of the supersonic nozzle.
8. The air conditioning apparatus according to claim 2, wherein the connecting device comprises: a connecting pipe comprising two parts, wherein an end of one of the two parts is connected to communicate with a side wall of the intake portion and an end of the other one of the two parts is connected to communicate with a side wall of the exhaust portion; and a pump connected with the other ends of the two parts of the connecting pipe.
9. The air conditioning apparatus according to claim 2, further comprising: a first filter sieve disposed at a position near the inlet.
10. The air conditioning apparatus according to claim 2, further comprising: a second filter sieve disposed after the heater and the humidifier and before the airflow export device.
11. The air conditioning apparatus according to claim 1, further comprising: a water collection tank disposed below the exhaust portion in a gravity direction and connected to communicate with the exhaust portion, wherein a pressure in the water collection tank is substantially equal to a pressure in the exhaust portion.
12. The air conditioning apparatus according to claim 11, further comprising: a filter module disposed between the water collection tank and the humidifier, wherein water in the water collection tank is adapted to flow to the humidifier after flowing through the filter module.
13. The air conditioning apparatus according to claim 1, further comprising: a power generation device disposed after the supersonic nozzle and before the heater and the humidifier to generate electricity when air flows by, wherein the power generation device is electrically connected with the heater.
14. The air conditioning apparatus according to claim 1, wherein an inner diameter of the throat is adjustable.
15. The air conditioning apparatus according to claim 1, further comprising: a silencer tube disposed at an end of the exhaust portion of the supersonic nozzle.
16. The air conditioning apparatus according to claim 1, wherein the connecting device comprises: a connecting pipe comprising two parts, wherein an end of one of the two parts is connected to communicate with a side wall of the intake portion and an end of the other one of the two parts is connected to communicate with a side wall of the exhaust portion; and a pump connected with the other ends of the two parts of the connecting pipe.
17. The air conditioning apparatus according to claim 1, further comprising: a first filter sieve disposed at a position near the inlet.
18. The air conditioning apparatus according to claim 1, further comprising: a second filter sieve disposed after the heater and the humidifier and before the airflow export device.
Description:
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to an air conditioning apparatus and more particularly relates to an air conditioning apparatus that is energy-saving and meets the demand for large airflow.
[0003] 2. Description of Related Art
[0004] Air conditioning equipment is mainly used for controlling ambient air temperature, humidity, air cleanliness, and air circulation. The current air conditioning equipment achieves the above purposes by a freezing or piezoelectric method.
[0005] The freezing method is to evaporate or condense a refrigerant through operation of a compressor, so as to evaporate or condense the ambient air to change the temperature or humidity. However, the freezing method consumes a great deal of electricity and requires refrigerant circulation. In the eco-friendly era, research on the energy-saving procedure has reached its bottleneck. The piezoelectric method is to create a temperature difference above and below the material through conversion of potential difference, so as to achieve the purpose of cooling. Although the piezoelectric method requires much less electrical energy, the generated airflow is insufficient for industries that require large airflow.
SUMMARY OF THE INVENTION
[0006] The invention provides an air conditioning apparatus that is energy-saving and meets the demand for large airflow.
[0007] An air conditioning apparatus of the invention includes a casing, an airflow import device, a supersonic nozzle, two valves, a vacuum pump, a connecting device, a heater, a humidifier, and an airflow export device. The casing has an inlet and an outlet. The airflow import device is disposed at a position near the inlet in the casing. The supersonic nozzle is disposed between the airflow import device and the outlet, and includes an intake portion, a throat, and an exhaust portion that are connected sequentially and coaxially. A cross-sectional area of the intake portion decreases gradually from one end away from the throat to the other end close to the throat. A cross-sectional area of the throat is smaller than a cross-sectional area of the exhaust portion. The two valves are disposed respectively at an inlet port of the intake portion and an outlet port of the exhaust portion. The vacuum pump is connected to communicate with the supersonic nozzle. The connecting device is connected with a side wall of the intake portion of the supersonic nozzle and a side wall of the exhaust portion, wherein the connecting device and the supersonic nozzle are non-coaxial. The heater and the humidifier are disposed between the supersonic nozzle and the outlet, wherein a sequence of the heater and the humidifier is not particularly limited. The airflow export device is disposed after the heater and the humidifier and at a position near the outlet in the casing.
[0008] In an embodiment of the invention, a sequence of the heater and the humidifier is one of the following: the heater being disposed before the humidifier and the humidifier being disposed before the heater.
[0009] In an embodiment of the invention, the air conditioning apparatus further includes a water collection tank disposed below the exhaust portion in a gravity direction and connected to communicate with the exhaust portion, wherein a pressure in the water collection tank is substantially equal to a pressure in the exhaust portion.
[0010] In an embodiment of the invention, the air conditioning apparatus further includes a filter module disposed between the water collection tank and the humidifier, wherein water in the water collection tank is adapted to flow to the humidifier after flowing through the filter module.
[0011] In an embodiment of the invention, the air conditioning apparatus further includes a power generation device disposed after the supersonic nozzle and before the heater and the humidifier to generate electricity when air flows by, wherein the power generation device is electrically connected with the heater.
[0012] In an embodiment of the invention, the air conditioning apparatus further includes a silencer tube disposed at an end of the exhaust portion of the supersonic nozzle.
[0013] In an embodiment of the invention, an inner diameter of the throat is adjustable.
[0014] In an embodiment of the invention, the connecting device includes a connecting pipe and a pump. The connecting pipe has two parts, wherein an end of one of the two parts is connected to communicate with a side wall of the intake portion and an end of the other one of the two parts is connected to communicate with a side wall of the exhaust portion. The pump is connected with the other ends of the two parts of the connecting pipe.
[0015] In an embodiment of the invention, the air conditioning apparatus further includes a first filter sieve disposed at a position near the inlet.
[0016] In an embodiment of the invention, the air conditioning apparatus further includes a second filter sieve disposed after the heater and the humidifier and before the airflow export device.
[0017] Based on the above, the air conditioning apparatus of the invention utilizes the airflow import device to lower the pressure at a front region of the casing (between the inlet and the intake portion of the supersonic nozzle) so as to cause air to flow from outside into the casing. By temporarily sealing the two valves at two ends of the supersonic nozzle and using the vacuum pump to create a vacuum in the supersonic nozzle, when the two valves are opened, the pressure in the supersonic nozzle, which is lower than the pressure at the front region of the casing, causes air to flow to the supersonic nozzle. According to the principles of aerodynamics and mass conservation, because the cross-sectional area of the intake portion decreases gradually from the end away from the throat toward the other end close to the throat, the air is accelerated to supersonic as flowing through the intake portion, and at the same time, the air is turned to a low-pressure and low-temperature state and causes a portion of moisture to be condensed. The air that leaves the supersonic nozzle is in the low-pressure and low-humidity state and can be adjusted to the required temperature and humidity through the heater and the humidifier, so as to meet the actual requirements. Moreover, in order to prevent a shock that occurs due to pressure compression when the air flows through a latter region of the casing (from the exhaust portion to the outlet), the air conditioning apparatus of the invention first uses the connecting device to draw a portion of the air in the exhaust portion back to the intake portion to increase the air flow rate in the intake portion and increase the outlet pressure of the exhaust portion, so as to reduce the pressure difference between the inside and the outside of exhaust portion when the air flows out of the exhaust portion. Further, the airflow export device disposed near the outlet maintains the pressure at the latter region of the casing in the low-pressure state so as to prevent the air from causing a shock when flowing through the heater and the humidifier, such that the airflow from the air conditioning apparatus is smooth.
[0018] To make the aforementioned and other features and advantages of the invention more comprehensible, several embodiments accompanied with drawings are described in detail as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention.
[0020] FIG. 1 is a schematic view of an air conditioning apparatus according to an embodiment of the invention.
[0021] FIG. 2 is a schematic view of a heater of the air conditioning apparatus shown in FIG. 1.
[0022] FIG. 3 is a schematic view of a power generation device of the air conditioning apparatus shown in FIG. 1.
[0023] FIG. 4 is a schematic view of a humidifier of the air conditioning apparatus shown in FIG. 1.
DESCRIPTION OF THE EMBODIMENTS
[0024] FIG. 1 is a schematic view of an air conditioning apparatus according to an embodiment of the invention. With reference to FIG. 1, an air conditioning apparatus 100 of this embodiment includes a casing 110, an airflow import device 120, a supersonic nozzle 130, two valves 140, a vacuum pump 145, a connecting device 150, a heater 160, a humidifier 165, and an airflow export device 125.
[0025] The casing 110 has an inlet 112 and an outlet 114. In this embodiment, the inlet 112 and the outlet 114 are respectively located near two sides of the casing 110 and on top of the casing 110, as shown in FIG. 1. However, it is noted that the positions of the inlet 112 and the outlet 114 may be varied according to the actual requirements. For example, the inlet 112 and the outlet 114 may be disposed on the left and the right sides of the casing 110 in FIG. 1. Nevertheless, the invention is not limited to the above.
[0026] The airflow import device 120 is disposed at a position near the inlet 112 in the casing 110. The airflow import device 120 is configured to generate a pressure difference to cause airflow. In this embodiment, the airflow import device 120 is a low-pressure blower, which is capable of reducing the pressure at a front region (between the inlet 112 and supersonic nozzle 130) of the casing 110 to allow air to flow from outside into the casing 110. For example, an external pressure is one atmosphere. The airflow import device 120 is capable of reducing the pressure at the front region of the casing 110 to 0.2 atm, such that the pressure difference therebetween causes the external air to flow into the casing 110.
[0027] The two valves 140 are respectively disposed at two ends of the supersonic nozzle 130. In this embodiment, the two valves 140 are two linked solenoid valves for simultaneously opening or closing the supersonic nozzle 130. In other embodiments, the valves 140 may also be opened or closed manually or by other means as long as the two ends of the supersonic nozzle 130 can be sealed. The invention is not intended to limit the types of the valves 140.
[0028] The vacuum pump 145 is connected to communicate with the supersonic nozzle 130. In this embodiment, when the air conditioning apparatus 100 is operating, the two valves 140 are closed first for the vacuum pump 145 to extract air inside the supersonic nozzle 130 to create a vacuum, which is a basic condition for forming a supersonic flow in the supersonic nozzle 130. When vacuum is formed in the supersonic nozzle 130, the two valves 140 are opened, and due to the pressure difference, air enters the supersonic nozzle 130.
[0029] The supersonic nozzle 130 includes an intake portion 132, a throat 134, and an exhaust portion 136 that are connected sequentially and coaxially. The intake portion 132 is in a convergent trumpet-like shape and has a cross-sectional area decreases gradually from one end away from the throat 134 to the other end close to the throat 134. Moreover, a cross-sectional area of the throat 134 is smaller than a cross-sectional area of the exhaust portion 136, such that a section from the throat 134 to the exhaust portion 136 is in a divergent shape.
[0030] According to the theories of aerodynamics and mass conservation, the shape change of the intake portion 132, the throat 134, and the exhaust portion 136 causes the air passing through the supersonic nozzle 130 to be accelerated to supersonic. The following is a mass conservation equation (1).
{dot over (m)}=ρVA=const (1)
[0031] {dot over (m)} represents a mass flow rate of air, ρ represents a density of air, and V represents a flow rate of air through a cross-sectional area A. That is, in the case that the mass flow rate of the air is a fixed value and the cross-sectional area of the intake portion 132 gradually decreases, the air is continuously accelerated as the air flows through the intake portion 132 and is accelerated to supersonic when the air passes the throat 134. At this moment, the air accelerated to supersonic no longer follows the principle of "the flow rate increases when the air flows through a smaller cross-sectional area; and the flow rate decreases when the air flows through a larger cross-sectional area." On the contrary, when the air accelerated to supersonic is pushed from the smaller cross-sectional area to the larger cross-sectional area, the flow rate continues to increase and remains in the supersonic state. In other words, when flowing through the exhaust portion 136, the air remains in the supersonic state.
[0032] In one of the embodiments, an inner diameter of the throat 134 is 10 cm, an inner diameter of the exhaust portion 136 is 11 cm, and a ratio of the cross-sectional area of the throat 134 to the cross-sectional area of the exhaust portion 136 is about 1:1.2. It is noted that the relationship between the sizes of the throat 134 and the exhaust portion 136 is not limited to the above. In another embodiment, the inner diameter/size of the throat 134 is adjustable. Accordingly, the user may vary the inner diameter of the throat 134 to adjust the airflow from the air conditioning apparatus according to the actual requirement. Of course, in the embodiment where the inner diameter/size of the throat 134 is adjustable, the shape of the intake portion 132, the throat 134, and the exhaust portion 136 remains the convergent and divergent form.
[0033] As the air flows through the supersonic nozzle 130, the air is not only accelerated but also turned into a low-pressure and low-temperature state, such that a portion of the moisture is condensed. In this stage, the temperature and humidity of the air that leaves the supersonic nozzle 130 are lower than what the user requires. Then, the air flows through the heater 160 and the humidifier 165, disposed between the supersonic nozzle 130 and the outlet 114, to be adjusted to the required temperature and humidity, so as to meet the user's requirement. For example, the air temperature outside is 25° C. and the relative humidity is 75%. After flowing through the supersonic nozzle 130, the temperature of the air may drop to 5° C. and the relative humidity may drop to 10% to 20%. After the air passes through the heater 160 and the humidifier 165, the temperature of the air exported from the air conditioning apparatus 100 is adjusted to 18° C. and the relative humidity is adjusted to 55% to meet the requirement.
[0034] FIG. 2 is a schematic view of a heater of the air conditioning apparatus shown in FIG. 1. With reference to FIG. 2, in this embodiment, the heater 160 is an electro-thermal net. The air is heated as the air passes a mesh of the heater 160. A power of the heater 160 is 5 kW. Of course, the designer may adjust the heating power and the mesh size of the heater 160, based on conditions such as the temperature required and the air flow rate, to achieve a required outlet temperature.
[0035] As shown in FIG. 1, in order to save energy, in this embodiment, the air conditioning apparatus 100 further includes a power generation device 170 disposed between the supersonic nozzle 130 and the heater 160 for generating electricity after high-speed air passes through. FIG. 3 is a schematic view of the power generation device of the air conditioning apparatus shown in FIG. 1. With reference to FIG. 3, the power generation device 170 is a mesh structure including a plurality of piezoelectric elements 172. When air flows through the power generation device 170, the airflow causes the piezoelectric elements 172 to vibrate and generate electricity. The power generation device 170 is electrically connected to the heater 160 so as to supply the generated electricity to the heater 160.
[0036] It is noted that, in other embodiments, the power generation device 100 may be a wind turbine including a plurality of fan blades, which are rotated by air to achieve the function of generating electricity. Moreover, in another embodiment, the air conditioning apparatus 100 may not be provided with the power generation device 170. In that case, external power is supplied to the heater 160. The heater 160 may also be a hot water pipe, a kerosene heater, or a gas stove, etc. The invention is not intended to limit the type of the heater 160.
[0037] FIG. 4 is a schematic view of the humidifier of the air conditioning apparatus shown in FIG. 1. With reference to FIG. 4, in this embodiment, the humidifier 165 is a mesh structure including a plurality of atomizing nozzles 167, by which liquid water is atomized and sprayed to a path of the air, so as to increase the relative humidity of the air. Similarly, the designer may vary the number and size of the atomizing nozzles 167 according to the required humidity.
[0038] In this embodiment, the air conditioning apparatus 100 further includes a water collection tank 175 and a filter module 177, wherein the water collection tank 175 is connected to communicate with the exhaust portion 136 and is disposed below in a gravity direction. The water collection tank 175 is sealed. That is to say, a pressure in the water collection tank 175 is substantially equal to the pressure in the exhaust portion 136. Thus, water condensed in the supersonic nozzle 130 falls into the water collection tank 175 due to gravity. Further, the filter module 177 is disposed between the water collection tank 175 and the humidifier 165. The water collected in the water collection tank 175 first flows through the filter module 177 for removing impurities and then flows to the humidifier 165 to serve as a moisture source for the humidifier 165. In this embodiment, the filter module 177 is a RO reverse osmosis module. However, it is noted that the invention is not intended to limit the type of the filter module 177.
[0039] It is noted that, in this embodiment, the heater 160 is disposed before the humidifier 165. Because the air conditioning apparatus 100 uses a method of dew point control (that is, applying the moisture content for the required dew point temperature when the air leaves the air conditioning apparatus 100) to control the outlet temperature and humidity of the air conditioning apparatus 100, the actual outlet humidity is not affected no matter the heating is performed before or after the humidification. Therefore, a sequence of the heater 160 and the humidifier 165, through which the air flows, is not particularly limited. In other embodiments, the humidifier 165 may be disposed before the heater 160.
[0040] It is worth mentioning that, in this embodiment, in order to prevent a shock that occurs when the air accelerated to supersonic undergoes pressure compression as flowing through the throat 134 and the exhaust portion 136 or flowing out of the exhaust portion 136 from affecting the air flow rate, the air conditioning apparatus 100 of this embodiment is provided with a connecting device 150 between the intake portion 132 and the exhaust portion 136 of the supersonic nozzle 130.
[0041] More specifically, as shown in FIG. 1, in this embodiment, the connecting device 150 includes a connecting pipe 152 and a pump 154. The connecting pipe 152 has two parts, an end of one of the two parts is connected to communicate with a side wall of the intake portion 132 and an end of the other one of the two parts is connected to communicate with a side wall of the exhaust portion 136. The connecting pipe 152 and the supersonic nozzle 130 are non-coaxial. The pump 154 is connected to the other ends of the two parts of the connecting pipe 152. The pump 154 is adapted to draw a small portion (about 2% to 5%) of the air in the exhaust portion 136 back to the intake portion 132. The connecting device 150 is mainly used to increase the flow rate of the air in the intake portion 132 and increase the outlet pressure of the exhaust portion 136, so as to reduce the pressure difference between the regions inside and outside the exhaust portion 136 when the air flows out of the exhaust portion 136, thereby deferring or eliminating pressure compression.
[0042] In addition, in order to prevent the shock that occurs due to pressure compression when the air flows through a latter region of the casing 110 (from the exhaust portion 136 to the outlet 114), the air conditioning apparatus 100 of this embodiment further includes the airflow export device 125 disposed at a position near the outlet 114 in the casing 110. In this embodiment, the airflow export device 125 is a blower. A ventilation volume of the airflow export device 125 is greater than a ventilation volume of the airflow import device 120, e.g. 1.05 to 1.1 times, such that the pressure at the latter region of the casing 110 is maintained in a low-pressure state at about 0.2 atm to prevent generation of the shock.
[0043] Furthermore, in order to reduce noise that is generated after the air passes the supersonic nozzle 130, in this embodiment, the air conditioning apparatus 100 further includes a silencer tube 180 disposed at the end of the exhaust portion 136 of the supersonic nozzle 130. In an initial stage of the operation, the valve 140 is closed, and when the air starts to flow, the valve 140 is opened to join the silencer tube 180. The silencer tube 180 reduces the noise by changing an overflow discharge method when the air flows by. For example, the silencer tube 180 has a larger expansion chamber for significantly expanding the air to reduce the flow rate, so as to reduce the noise of the air conditioning apparatus 100.
[0044] Moreover, in this embodiment, the air conditioning apparatus 100 further includes a first filter sieve 190 disposed at a position near the inlet 112 to separate dust from the air. In addition, if the air conditioning apparatus 100 is used in a high standard environment, such as a cleanroom, the air conditioning apparatus 100 may further include a second filter sieve 195 disposed at a position near the outlet 114. The second filter sieve 195 is disposed after the heater 160 and the humidifier 165 and before the airflow export device 125. An aperture of the second filter sieve 195 is smaller than an aperture of the first filter sieve 190, so as to filter fine dust particles from the air.
[0045] To sum up, the air conditioning apparatus of the invention utilizes the airflow import device to lower the pressure at the front region of the casing (between the inlet and the intake portion of the supersonic nozzle) so as to cause air to flow from outside into the casing. By temporarily sealing the two valves at two ends of the supersonic nozzle and using the vacuum pump to create a vacuum in the supersonic nozzle, when the two valves are opened, the pressure in the supersonic nozzle, which is lower than the pressure at the front region of the casing, causes air to flow to the supersonic nozzle. According to the principles of aerodynamics and mass conservation, because the cross-sectional area of the intake portion decreases gradually from the end away from the throat toward the other end close to the throat, the air is accelerated to supersonic as flowing through the intake portion, and at the same time, the air is turned to a low-pressure and low-temperature state and causes a portion of moisture to be condensed. The air that leaves the supersonic nozzle is in the low-pressure and low-humidity state and can be adjusted to the required temperature and humidity through the heater and the humidifier, so as to meet the actual requirements. Moreover, in order to prevent a shock that occurs due to pressure compression when the air flows through the latter region of the casing (from the exhaust portion to the outlet), the air conditioning apparatus of the invention first uses the connecting device to draw a portion of the air in the exhaust portion back to the intake portion to increase the air flow rate in the intake portion and increase the outlet pressure of the exhaust portion, so as to reduce the pressure difference between the inside and the outside of exhaust portion when the air flows out of the exhaust portion. Further, the airflow export device disposed near the outlet maintains the pressure at the latter region of the casing in the low-pressure state so as to prevent the air from causing a shock when flowing through the heater and the humidifier, such that the airflow from the air conditioning apparatus is smooth. The air conditioning apparatus of the invention utilizes the strong airflow generated from the supersonic nozzle and recovers energy through the power generation device, so as to achieve energy saving.
[0046] It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention covers modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.
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