Abstract:
The present invention provides a low power consumption desorption apparatus, which utilizes a pair of electrodes coupled to an absorbing material to provide an electric current flowing through the absorbing material so as to desorb the substances absorbed within the absorbing material. By means of the desorption apparatus of the present invention, the absorbing material is able to enhance the desorbing efficiency and reducing power consumption during desorption. The present invention further provides a dehumidifier using the low power consumption desorption apparatus for providing a continuous dry air flow to desorb and regenerate the moisture from the absorbing material so that the dehumidifier is capable of removing moisture in the air repeatedly to reduce the humidity.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to an environmental control technology and, more particularly, a low power consuming desorption apparatus and dehumidifier using the same wherein a voltage is applied across electrodes on both ends of a conductive material for desorption. 
     BACKGROUND OF THE INVENTION 
     Conventionally, the household dehumidifier uses a refrigerant compressor to condense the moisture in the air to achieve dehumidification. However, the use of refrigerant results in problems such as ozone layer depletion. Therefore, there is the need in developing a novel dehumidification technique without using refrigerant. 
     In rotary desiccant dehumidification, the refrigerant compressor is not required; instead, an absorbing material is used to absorb the moisture in the air and then electrical-thermal heater is used to heat up the gas flow through a regenerating area of the absorbing material to desorb the moisture. The high-temperature and high-moisture gas through the regenerating channels is introduced into a heat exchanger for condensation. The condensed moisture is then collected by a water collector to achieve household dehumidification. Since dehumidificaton achieved by the rotary dehumidifier using an absorbing material is temperature and humidity independent and refrigerant free, it is advantageous in low noise and low cost without using the compressor. 
     In the rotary desiccant dehumidifier  1 , as shown in  FIG. 1 , a moist gas flow  90  flows through a heat exchanger  10  into an absorbing material  11  so that the absorbing material  11  is capable of absorbing the moisture in the gas flow  90 . The dehumidified gas flow  92  is released by a dehumidifying blower  12  to achieve dehumidification. On the other hand, an electric heater  13  heats up the temperature of a circulating gas flow  91 . The water molecules in the absorbing material  11  is vaporized and desorbed by the temperature difference between the high-temperature circulating gas flow  91  and the water molecules in the absorbing material  11 . Then, the high-temperature high-moisture circulating gas flow  91  enters the heat exchanger  10  to perform heat transfer with the low-temperature moist gas flow  90  at the entrance of the dehumidifier  1 . The high-temperature high-moisture gas in the heat exchanger  10  can be condensed into liquid-phase water  93 , which is then collected and exhausted. The circulating gas flow  91  returns to the electric heater  13  to repeat the aforesaid processes to complete moisture desorption. The absorbing material  11 , the electric heater  13  and the heat exchanger  10  are integrated to achieve the dehumidification as a dehumidifier  1 . 
     The absorbing material in a rotary dehumidifier is mostly porous. For example, the porous structure can be honeycomb type or corrugate type. Dehumidification uses physical absorption to absorb water molecules in the air by micro pores of absorbent to produce dried air. The absorbing capability of the rotary dehumidifier depends on, for example, the type and the amount of the absorbent, the temperature and humidity of the incoming air, the thickness of the rotary dehumidifier, the surface area of the honeycomb, the speed of the gas flow through the rotary dehumidifier, and the rotational speed of the rotary dehumidifier. A regenerating circulating flow channel is required to desorb the absorbed moisture from the dehumidifier. Therefore, dehumidification-regeneration is achieved by continuous absorption and desorption. The referred regenerating flow channel starts from the interface between the electric heater  13  and the absorbing material  11  (rotary dehumidifier) through the heat exchanger  10  and ends at the inlet where the gas flow enters the electric heater  13 . For the absorbing material  11  (rotary dehumidifier), the gas flow inlet is a regeneration area of the rotary dehumidifier and the gas flow outlet is on the regeneration area wheel before the high-temperature and high-humidity gas enters the heat exchanger. In a rotary dehumidifier system, after the high-temperature and high-humidity gas on the regeneration side enters the condenser, heat exchange takes place between the high-temperature and high-humidity gas and the low-temperature gas outside the pipeline. Therefore, the high-temperature high-moisture gas in the condenser can be condensed into liquid-phase water. 
     In conventional rotary desiccant dehumidification, an electric heater is used to heat up the gas flow on the regenerating area to increase the temperature of the regenerating air. The thermal desorption mechanism comprises two approaches. One is vaporization by heat exchange of the gas flow, wherein a temperature gradient occurs as the circulating gas flow is heated up and the moisture is vaporized and desorbed from the absorbing material by the energy generated during heat exchange. However, this approach costs high power consumption to achieve dehumidifying because it takes a long time for vaporization to generate high-temperature gas required during moisture desorption. The other approach is vaporization by thermal radiation, wherein high-temperature gas is obtained by conducting a current flowing through a heating wire in the heater. Thermal radiation enables the water molecules in the absorbing material to receive the heat to be vaporized to desorb from the absorbing material. Since the radiated heat is proportional to the surface temperature to the power of four and the surface temperature of the electric heater is higher than 400° C., the radiated heat is very high. Therefore, the moisture desorption effect is much more important than vaporization by heat exchange of the gas flow. Accordingly, in the aforesaid two approaches, conventional desorption approaches by heating up the circulating gas flow or thermally radiating the water molecules to achieve desorption inevitably lead to high power consumption since the radiated heat is mostly absorbed by the absorbing material. Moreover, the radiated heat increases the surface temperature of the absorbing material, which adversely affects the absorption of water molecules by the desiccative to reduce the dehumidifying performance. Therefore, in a rotary dehumidifier, the power consumption is high and dehumidification efficiency is reduced. 
     SUMMARY OF THE INVENTION 
     The present invention provides a low power consumption desorption apparatus using electrodes disposed on both ends of an absorbing material so as to conduct an electric current flowing through the absorbing material to raise the temperature and desorb a substance absorbed by the absorbing material since the attractive force between the absorbed molecules and the absorbing material may change under some circumstances. Moreover, a regenerating gas path can be provided in a region corresponding to the electrodes so that the gas flow passes through the absorbing material to enhance the desorption rate. 
     The present invention provides a dehumidifier, by applying an electric current through the absorbing material between two electrodes to absorb the moisture in the air to reduce the humidity. Since the dehumidifier produces a regenerating circulating gas flow that carries the desorbed moisture, the absorbing material is capable of performing desorption without heating up the gas so as to reduce power consumption. 
     In one embodiment, the present invention provides a low power consumption desorption apparatus, comprising: an absorbing material capable of absorbing at least a substance; a pair of electrodes coupled to both ends of the absorbing material, each of the electrodes comprising a plurality of sub-electrodes being insulated from one another; and a voltage supply coupled to the pair of electrodes and providing the pair of electrodes with a voltage so that the absorbing material is conductive to perform desorption. 
     In another embodiment, the present invention further provides a dehumidifier, comprising: a condenser capable of providing a circulating gas flow; an absorbing material capable of allowing a gas flow to pass through to absorb at least a substance in the gas flow; a regenerating portion coupled to the condenser and the absorbing material, the regenerating portion guiding the circulating gas flow to pass through the absorbing material and further comprising a pair of electrodes coupled to both ends of the absorbing material, each of the electrodes comprising a plurality of sub-electrodes being insulated from one another; a voltage supply coupled to the pair of electrodes and providing the pair of electrodes with a voltage so that the absorbing material is conductive to perform desorption. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects, spirits and advantages of the embodiments of the present invention will be readily understood by the accompanying drawings and detailed descriptions, wherein: 
         FIG. 1  is a 3-D exploded view of a conventional rotary dehumidifier; 
         FIG. 2  is a schematic diagram of a low power consumption desorption apparatus according to one embodiment of the present invention; 
         FIG. 3A  is a front view of an electrode according to one embodiment of the present invention; 
         FIG. 3B  is a cross-sectional view of the electrode in  FIG. 3A  and the absorbing material according to one embodiment of the present invention; 
         FIG. 4  is a schematic diagram showing the operation of electrodes according to one embodiment of the present invention; 
         FIG. 5A  and  FIG. 5B  are schematic diagrams of an electrode according to other embodiments of the present invention; 
         FIG. 6  is a schematic diagram showing the operation of electrodes connected to a regenerating gas path according to one embodiment of the present invention; 
         FIG. 7  is a front view of an electrode according to another embodiment of the present invention; 
         FIG. 8A to 8C  are schematic diagrams of a rotating regenerating gas path according to the present invention; 
         FIG. 9  shows the testing result of a dehumidifier using the electrodes and the absorbing material of the present invention; and 
         FIG. 10  is a schematic diagram of a dehumidifier according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention can be exemplified but not limited by the preferred embodiments as described hereinafter. 
     Please refer to  FIG. 2 , which is a schematic diagram of a low power consumption desorption apparatus according to one embodiment of the present invention. In the present embodiment, the desorption apparatus  3  comprises an absorbing material  30 , a pair of electrodes  31  and  32  and a voltage supply  33 . The absorbing material  30  is capable of absorbing volatile organic substances in the air, exemplified by, but not limited to, nitrogen or water moisture. Generally, the absorbing material is usually used in household dehumidifiers, such as rotary dehumidifier, but not limited thereto. The absorbing material can be made of porous materials such as zeolite, silicone, silica gel, active carbon, carbon nano tubes, metal organic frameworks. Moreover, the absorbing material may also be formed of non-porous materials such as dehydrogenated metal. 
     The pair of electrodes  31  and  32  are connected to the both ends of the absorbing material  30 . The voltage supply  33  is coupled to the electrodes  31  and  32  to provide the electrodes  31  and  32  with a voltage. The voltage supply  33  provides an AC voltage or a DC voltage. Since the electrodes  31  and  32  are disposed on the two ends of the absorbing material  30 , the temporary high potential dissolves the absorbed substance or combines the absorbed substance and specific metal ions to cause ion conduction. Therefore, the conduction between the absorbed substance and the absorbing material may change so that the absorbed substance is desorbed from the absorbing material. The electric current is induced due to ion hopping in the absorbing material, ion/proton transport in the ionized substance or both. As a result, the heat loss is reduced and the power consumption is reduced because there is no need to heat up the atmosphere. 
     In order to perform desorption only in some specific region in the absorbing material while remaining absorption in other region when the absorbing material is rotating, the electrodes are further provided with insulators to divide the electrodes into a plurality of regions. Each of the regions is isolated from one another so that only some region of the electrodes is conductive when a voltage is applied to enable the corresponding absorbing material to perform desorption while remaining absorption in other regions. 
     Please refer to  FIG. 3A , which is a front view of an electrode according to one embodiment of the present invention. In the present embodiment, taking the electrode  31  for example, the electrode  31  comprises a plurality of sub-electrodes  310 . Since the absorbing material of the present invention is cylindrical, each of the sub-electrodes  310  is fan-shaped. Each of the sub-electrodes  310  comprises an insulating frame  311  and a conductor  312 . In the present embodiment, the insulating frame  311  is disposed on both sides of the sub-electrode  310  so that the adjacent sub-electrodes  310  are insulated from one another. The insulating frame  311  may comprise semi-friable fused alumina, ceramic, quartz, polymer, Teflon, peek, epoxy resin or combination thereof. In the present embodiment, the thickness of the insulator is within a range from 1 mm to 5 mm. The conductor  312  is disposed on the boundary of the sub-electrode  310 . In the present embodiment, the conductor  312  is a metal rod or a metal wire. 
     In order to enhance the conductivity of the conductor  312 , the conductor  312  further comprises a metal net  313  with regular or irregular pores on the surface to allow gas to flow into the absorbing material  30 . The material for making the metal net  313  is not limited, as long as it comprises conductive metal. Please refer to  FIG. 3B , which is a cross-sectional view of the electrode in  FIG. 3A  and the absorbing material according to one embodiment of the present invention. The cross-sectional view is taken along the FF direction in  FIG. 3A  to show the electrodes, the insulating frame  311  and the absorbing material in  FIG. 3B . A conductive layer  314  is further provided between the metal net  313  and the absorbing material  30  to reduce the contact resistance and uniformize the electric current. In the present embodiment, the conductive layer  314  comprises an anti-oxidation conductive material to strengthen and stabilize the circuitry between each of the sub-electrodes  310  and the absorbing material  30  to prevent abnormal discharge that may destroy the absorbing material. The conductive layer  314  may comprise a metal material such as gold (Au) and platinum (Pt), an alloy such as stainless steel or any conductive metal oxide or non-metal oxide such as indium tin oxide (ITO, In 2 O 3 +SnO 2 ) or a kind of carbon material such as graphite, active carbon, which can be formed by conventional techniques such as sputtering, evaporation, spray, painting or dipping. The metal net is provided so as to protect the conductive layer from being damaged. 
     Please refer to  FIG. 4 , which is a schematic diagram showing the operation of electrodes according to one embodiment of the present invention. Since the absorbing material of the present embodiment is capable of performing a rotational movement, the voltage supply  33  is further coupled to a brush  330  so that each of the sub-electrodes  310  can conduct an electric current independently. When the absorbing material  30  is rotating, the brush  330  is capable of being electrically connected to different sub-electrodes  310  in order. In  FIG. 4 , when the absorbing material  30  is rotating, the metal frame  312  that contacts the brush  330  is capable of conducting an electric current throughout all the sub-electrodes  310 . Since the electrodes  31  and  32  correspond to each other, a region  300  of the absorbing material corresponding to a portion between the sub-electrodes  310  and  320  that contact the brush  330  is conductive due to an electric field between the sub-electrodes  310  and  320 . Since the electrodes  31  and  32  of the present invention are provided with the insulating frames  311  and  321 , desorption is only performed in the desorption region where electric conduction takes place because only the desorption region corresponds to the contact when the brush  330  contacts the metal frame  312  and  322  of the electrodes  31  and  32 . On the other hand, other regions of the absorbing material  30  remain absorption. In this manner, the absorbing material  30  is capable of performing absorption and desorption at the same time. 
     Please refer to  FIG. 5A  and  FIG. 5B  for the schematic diagrams of an electrode according to other embodiments of the present invention. In  FIG. 5A , the electrode  31  may comprise an anti-oxidation conductive layer  314   a  capable of being coated on the surface of the absorbing material  30 . With the gap  314 b as an insulating portion, the electrode  31  comprises a plurality of sub-electrodes. In  FIG. 5A , in addition to the gap, an insulating frame can be further disposed in the gap  314   b  to enhance insulation. In  FIG. 5B , to enhance electric contact, a conductor  314   c  is further provided on the boundary of each of the sub-electrodes. The conductor  314   c  may be a metal rod, a metal wire or a metal net. Even though  FIG. 5A  and  FIG. 5B  show embodiments for the electrode  31 , the electrode  32  may also be implemented by the same embodiments. 
     Referring to  FIG. 6 , a regenerating gas path  34  is provided on both ends of the desorption region corresponding to the brush  330 . The regenerating gas path  34  is capable of introducing the gas flow  90  into the corresponding conductive desorption region and exhausting the desorbed substance to enhance the desorption rate. To further improve the desorption rate, the gas flow  90  can be heated up to a higher temperature to speed up desorption. 
     In the previous embodiment, the absorbing material is capable of rotating. In another embodiment, however, the absorbing material is electrically connected to the brush without rotating. Instead, each of the sub-electrodes is conducted with an electric current by power distribution control. Please refer to  FIG. 7 , which is a front view of an electrode according to another embodiment of the present invention. Taking the electrode  31  for example, the electrode  31  can be divided into a plurality of sub-electrodes being insulated from one another  315  and  315   a  to  315   g , each of which comprising an external metal frame  316  and an internal metal frame  317 . Insulating frames  318  and  319  are provided between the external metal frame  316  and the internal metal frame  317 . A conducting wire  332  is independently introduced from each of the sub-electrodes  315  and  315   a  to  315   g . Each of the sub-electrodes  315  and  315   a  to  315   g  can be connected to the conducting wire  332  at the external metal frame  316  or the inner metal frame  317 . The conducting wire  332  corresponding to each of the sub-electrodes  315  and  315   a  to  315   g  is connected to a power distribution unit  331 . The power distribution unit  331  is electrically connected to the voltage supply  33 . The power distribution unit  331  is capable of receiving a positioning signal so as to provide specific sub-electrodes with power in order. For example, electricity is firstly supplied to the sub-electrode  315  on the absorbing material and then to the sub-electrode  315   a  to  315   g  in order. Such a power supplying order is equivalent to that of a rotating absorbing material. Since there are insulating frames between the sub-electrodes, it is ensured that only the specific region is conductive when the electrodes are applied with an electric current to perform desorption on the regions corresponding to the sub-electrodes, while absorption remains in the regions where the sub-electrodes are not applied with an electric current. The power distribution unit  331  comprises an arithmetic logic unit, a timer, and a power switch. The power switch can be a mechanical relay, a power distribution panel or a solid-state switch made of semiconductor. The power distribution unit of the present embodiment is conventionally known and description thereof is not repeated herein. 
     Please refer to  FIG. 8A  and  FIG. 8B , wherein  FIG. 8A  is a side view of a rotational regenerating gas path of the present invention,  FIG. 8B  is a 3-D view of an inlet of the rotational regenerating gas path. In the present embodiment, the absorbing material  30  is still, while the regenerating gas path  35  and the gas collecting path  36  are rotating. The positions of the regenerating gas path  35  and the gas collecting path  36  are detected by a positioning sensing module. In the present embodiment, the regenerating gas path  35  and gas collecting path  36  correspond to each other and are capable of synchronously performing a rotational movement. The regenerating gas path  35  comprises a housing  350  capable of allowing a gas flow  355  to enter. The housing  350  is connected to a shaft  351 , which is capable of receiving rotating power from a rotating power provider such as a motor to drive the housing  350  of the regenerating gas path to rotate. The shaft  351  further comprises a flow channel  352  capable of allowing a gas flow  355  to enter. Since the gas collecting path  36  is driven by the shaft  351  and the regenerating gas path  35  to rotate synchronously, the gas flow  355  passing through the absorbing material  30  is carried out through the gas collecting path  36 . The positioning sensing module is a mechanical structure, an optical detection device, a magnetic detection device or a sonic detection device that provides replacement detection, for example, a micro switch, a photo-sensitive switch, a reed switch or a ultra-sonic sensor. In the present embodiment, the optical module comprises a light emitting device  354  disposed on the regenerating gas path  35 . Another light receiving device  353  is disposed on each of the sub-electrodes. When the regenerating gas path completely covers the sub-electrodes, a positioning control signal is issued in real time to the power distribution unit. The power distribution unit stops the regenerating gas path from rotating and outputs power to the sub-electrodes that are covered for regeneration processes. The gas collecting path is not only limited as described but also can be designed as shown in  FIG. 8C , where the gas collecting path  37  is not rotating and is disposed on the other side of the absorbing material  30  to collect the gas flow  355  flowing through the absorbing material. 
     The aforementioned desorption method can be used with any conductive absorbing material and absorbed substances in applications such as fixed-bed dehumidifiers, tower dehumidifiers and rotary dehumidifiers.  FIG. 9  shows the testing result of a dehumidifier using the electrodes and the absorbing material of the present invention. In  FIG. 90 , the desorption capability is 6.6 liter/day (20° C., 60% RH), desorption is achieved with convection heating with power consumption of 600 watts (as shown in  FIG. 9 ). In other words, it takes 7854 J of energy to desorb 1 gram of water. When the dehumidification wheel is not rotating and a voltage is applied across the electrodes without convection heating, the power consumption is only 4200˜4700 J/g. In  FIG. 9 , the longitudinal axis represents the weight reduction of the dehumidification wheel, indicating the amount of desorbed water, while the traversal axis represents time. Different curves represent the results of different experiments each with different time. Each experiment is conducted at a constant voltage of 90 V. The absorbing material comprises zeolite and silicone with a diameter of 77 mm. Different desorption times result in different outcomes. In  FIG. 9 , ▴ denotes that the desorption time is 3 seconds; ▪ denotes that the desorption time is 6 seconds; ♦ denotes that the desorption time is 10 seconds; and ● denotes that the desorption time is 15 seconds. The values shown in  FIG. 9  are measured power consumption values divided by the amount of desorbed water. In  FIG. 9 , it is observed that optimum desorption is achieved with less power consumption when the absorbing material is applied with an electric current for 6 seconds. In other words, with the electrodes being applied with an electric current, the power consumption is 45% reduced (dropping from 7854 J/g to 4200 J/g). Even though the values in  FIG. 9  are obtained when the dehumidification wheel is not rotating, this method can be used in various applications such as tower dehumidifiers and rotary dehumidifiers with different electrode designs. 
     The aforesaid desorption apparatus can be used in a dehumidifier provided in the present invention. Please refer to  FIG. 10 , which is a schematic diagram of a dehumidifier according to one embodiment of the present invention. The dehumidifier  4  comprises a condenser  40 , an absorbing material  41  and a regenerating portion  42 . The condenser  40  comprises a condenser plate  401  and a circulating pipeline  402 . The condenser plate  401  comprises an inlet  4010  and an outlet  4012 . In the present embodiment, the condenser plate  401  comprises a plurality of condenser pipelines  4011  comprising a flowing path for a circulating gas flow  91  to flow therein. Since the condenser plate  401  is provided to enable a gas flow  90  to be dehumidified to pass through so that a heat exchange process is performed between the gas flow  90  and the circulating gas flow  91  in the condenser plate  401 , so that the moisture in the circulating gas flow in the condenser plate  401  is condensed into water to be collected in a water collector  46 . There are interstices between the condenser pipelines  4011  to enable the gas flow  90  to pass through. The condenser plate  401  is well-known to those with ordinary skills in the art, and thus the description thereof is not presented. The regenerating portion  42  is coupled to the absorbing material  41 . The regenerating portion  42  comprises a pair of electrodes  421  and  422 , a regenerating gas path  423  and a regenerating blower  424 . The pair of electrodes  421  and  422  are coupled similarly to the foresaid electrode  31  and  32 , and thus description thereof is not repeated. The regenerating gas path  423  comprises a housing  4230  as a gas flow channel. On one side of the housing  4230  is provided an outlet  4231  channeled with the inlet  4010  of the condenser plate  401 . On the other side of the housing  4231  is provided an inlet  4232  channeled with the regenerating blower  424 . The regenerating blower  424  is capable of increasing the pressure of the circulating gas flow  91  to accelerate the circulating gas flow  91 . 
     The absorbing material  41  is capable of allowing the gas flow  90  to pass through. The absorbing material  41  comprises micro-structures  410  therein to absorb moisture in the gas flow  90 . In the present embodiment, the absorbing material  41  is a roller capable of rotating. Certainly, the absorbing material  41  is not restricted to a roller in the present invention. The absorbing material  41  is well-known to those with ordinary skills in the art, and thus the description thereof is not presented. 
     As the absorbing material  41  rotates to a fixed position, the sub-electrodes  4210  and  4220  corresponding to the regenerating gas path  42  can be coupled to the voltage supply  45 . Therefore, the electric current helps to desorb the substance absorbed in the absorbing material  411  corresponding to the sub-electrodes  4210  and  4220 . In the present embodiment, the regenerating portion  22  comprises a housing  4230  capable of allowing the circulating gas flow  91  to pass through. The housing  4230  covers part of the absorbing material  41 , so that the circulating gas flow  91  in the housing  4230  passes through the absorbing material  41  to carry out the desorbed substance in the absorbing material  21  after an electric current is applied. 
     In order to accelerate the dehumidified gas flow  90  to better control dehumidification, the present embodiment further provides a dehumidifying blower  44  capable of exhausting the dehumidified gas flow  92  passing through the absorbing material  41  out of the dehumidifier  4 . Moreover, the dehumidifier  4  further comprises a heating unit  43 . In the present embodiment, the heating unit  43  is disposed between the inlet  4232  of the regenerating portion  42  and the regenerating blower  424 . The heating unit  43  is capable of providing the circulating gas flow  91  with thermal energy to increase the temperature of the circulating gas flow  91  to further enhance condensation of the desorbed moisture. 
     Accordingly, the present invention discloses a low power consumption desorption apparatus and a dehumidifier using the method, wherein a voltage is applied across electrodes on both ends of a conductive material for desorption. Therefore, the present invention is useful, novel and non-obvious. 
     Although this invention has been disclosed and illustrated with reference to particular embodiments, the principles involved are susceptible for use in numerous other embodiments that will be apparent to persons skilled in the art. This invention is, therefore, to be limited only as indicated by the scope of the appended claims.