Abstract:
A method and an apparatus for desorption and a dehumidifier are provided in the present invention, in which an electrical potential is applied to electrodes disposed on both ends of an absorbing material so as to desorb the substances absorbed within the absorbing material whereby the absorbing material is capable of being maintained for cycling the absorbing operation. By means of the method and the apparatus of the present invention, the desorbing efficiency can be enhanced and the energy consumption can be reduced during desorption.

Description:
1. FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a dehumidifying technology and, more particularly, to a method and an apparatus for desorption and a dehumidifier using the method and the apparatus wherein a voltage is applied across electrodes on both ends of an absorbing material for desorption. 
       2. BACKGROUND OF THE INVENTION 
       [0002]    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 need in developing a novel dehumidification technique without using refrigerant. 
         [0003]    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 heating is used to heat up the gas flow through a regenerating side of the absorbing material to desorb the moisture. The high-temperature and high-moisture gas on the regenerating side is introduced into a heat exchanger to be condensed and the condensed moisture is then collected by a water collector to achieve household dehumidification. Since dehumidification 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. 
         [0004]    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 . In conventional rotary desiccant dehumidification, an electric heater is used to heat up the gas flow on the regenerating side 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 to desorb from the dehumidifying structure in the absorbing material by the energy generated during heat exchange. However, this approach costs high power consumption to achieve dehumidification 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. 
         [0005]    To overcome this drawback, please refer to  FIG. 2 , which is a schematic diagram of a conventional plasma dehumidifier/humidifier disclosed in Japanese Patent Laid-Open Publication No. 2001-179037. In  FIG. 2 , two electrodes  15  and  16  disposed on both sides of a dehumidifying unit  17  are used to generate plasma to desorb the moisture absorbed by the dehumidifying unit  17 . Even though, in this pant, a plasma-enhanced moisture desorption technique is disclosed to reduce power consumption, both a dehumidifier and a humidifier are required in the chambers  18  and  19  because it is based on an open gas flow design. Therefore, this technique is used in a large-size open gas flow system. Moreover, the electrodes  15  and  16  are thermally activated, wherein a low voltage (5 to 10 volts) is used to activate the electrodes to generate plasma. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a dehumidifier using charged particles to perform water desorption to enhance water desorption efficiency of a rotator, reduce power dissipation of a heater and improve dehumidification efficiency of a rotary dehumidifier. Since the power dissipation is reduced, the dehumidifier of the present invention can be used to replace the conventional high power-consumption electrical-thermal dehumidification system for water desorption. 
         [0007]    The first present invention provides an apparatus for a dehumidifier, using a high voltage to discharge the electrodes and ionize the gas flow through the regenerator to generate charged particles, which enable water molecules to be easily desorbed so that the desiccative in the dehumidifier exhibits sufficient desorptivity at a low temperature or without heating up the gas. 
         [0008]    The second present invention provides a low power consumption desorption method, conducting a current flowing through an absorbing material to desorb a substance absorbed by the absorbing material to reduce power consumption for desorption and enhance desorption efficiency. 
         [0009]    The present invention provides a low power consumption desorption apparatus using electrodes disposed on both ends of an absorbing material so as to conduct a current flowing through the absorbing material to desorb a substance absorbed by the absorbing material. Moreover, a gas flow channel 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. 
         [0010]    The present invention provides a dehumidifier with minimum waste of energy in heating up water molecules and an absorbing material to significantly reduce power consumption and, hence, thermal loss. Moreover, the absorbing material is less heated so that the dehumidification efficiency of the dehumidifier is improved. 
         [0011]    In one embodiment, the present invention provides dehumidifier, comprising: 
         [0012]    a condenser, capable of containing a circulating gas flow therein; 
         [0013]    a absorbing material, capable of allowing a gas flow to pass through to absorb moisture in the gas flow; and 
         [0014]    a regenerating portion, being dispose on one side of the absorbing material and being connected to the condenser, wherein the circulating gas flow is ionized by plasma in the regenerating portion so that the ionized circulating gas flow desorbs the moisture in the absorbing material. 
         [0015]    In another embodiment, the present invention further provides a regenerator for a dehumidifier, comprising: 
         [0016]    a pair of electrodes disposed a distance apart, each of the electrodes comprising a plurality of gas channels; and 
         [0017]    a pair of insulators, being respectively connected to the pair of electrodes, each of the insulators comprising a plurality of insulating structures, each of the insulating structures corresponding to one of the gas channels respectively. 
         [0018]    In one embodiment, the present invention further provides a low power consumption desorption method, comprising steps of: 
         [0019]    providing an absorbing material; 
         [0020]    providing electrodes on both ends of the absorbing material; and 
         [0021]    applying a voltage across the electrodes on the both ends of the absorbing material so that the absorbing material is conductive to perform desorption. 
         [0022]    In another embodiment, the present invention further provides a low power consumption desorption apparatus, comprising: 
         [0023]    an absorbing material capable of absorbing at least a substance; 
         [0024]    a pair of electrodes disposed on both ends of the absorbing material; and 
         [0025]    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. 
         [0026]    In another embodiment, the present invention further provides a low power consumption desorption apparatus, comprising: 
         [0027]    an absorbing material capable of absorbing at least a substance; 
         [0028]    a pair of electrodes disposed on both ends of the absorbing material; 
         [0029]    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; and 
         [0030]    a gas flow channel disposed corresponding to the pair of electrodes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The objects, spirits and advantages of the embodiments of the present invention will be readily understood by the accompanying drawings and detailed descriptions, wherein: 
           [0032]      FIG. 1  is a 3-D exploded view of a conventional dehumidifier using electrical-thermal desorption; 
           [0033]      FIG. 2  is a schematic diagram of a conventional plasma dehumidifier/humidifier; 
           [0034]      FIG. 3  is a schematic diagram of a first embodiment of a dehumidifier according to the present invention; 
           [0035]      FIG. 4A  is a schematic diagram of a regenerating portion according to a first embodiment of the present invention; 
           [0036]      FIG. 4B  is a 3-D view of an electrode and an insulator in  FIG. 4A ; 
           [0037]      FIG. 5  is a flowchart of a low power consumption desorption method according to a second embodiment of the present invention; 
           [0038]      FIG. 6  is a schematic diagram of a second embodiment of a low power consumption desorption apparatus of the present invention; 
           [0039]      FIG. 7A  is a front view of an electrode according to one embodiment of the present invention; 
           [0040]      FIG. 7B  is a cross-sectional view of an electrode and an absorbing material according to one embodiment of the present invention; 
           [0041]      FIG. 8  is a schematic diagram showing the operation of electrodes according to one embodiment of the present invention; 
           [0042]      FIG. 9  is a schematic diagram showing the operation of electrodes connected to a gas flow channel according to one embodiment of the present invention; and 
           [0043]      FIG. 10  shows the testing result of a dehumidifier. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0044]    The present invention can be exemplified but not limited by the preferred embodiments as described hereinafter. 
         [0045]    Please refer to  FIG. 3 , which is a schematic diagram of a first embodiment of a dehumidifier according to the present invention. The dehumidifier  2  comprises a condenser  20 , an absorbing material  21  and a regenerating portion  22 . The condenser  20  comprises a condenser plate  201  and a regenerating blower  202 . An inlet  2010  of the condenser plate  201  is channeled with an inlet  220  of the regenerating portion  22  through a pipeline. To simplify  FIG. 3 , the pipeline is not shown, while those with ordinary skills in the art can understand the present invention. In the present embodiment, the condenser plate  201  comprises a plurality of condenser pipelines  2011 , comprising a flowing path for a circulating gas flow  91  to flow therein. Since the condenser plate  201  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  201 , there are interstices between the condenser pipelines  2011  to enable the gas flow  90  to pass through. The condenser plate  201  is well-known to those with ordinary skills in the art, and thus the description thereof is not presented. The regenerating blower  202  is coupled to the inlet  2012  of the condenser plate  201  and the inlet  221  of the regenerating portion  22 . The regenerating blower  202  is capable of increasing the pressure of the circulating gas flow  91  to accelerate the circulating gas flow  91 . 
         [0046]    The absorbing material  21  is capable of allowing the gas flow  90  to pass through. The absorbing material  21  comprises micro-structures  210  therein to absorb moisture in the gas flow  90 . In the present embodiment, the absorbing material  21  is a roller capable of rotating. Certainly, the absorbing material  21  is not restricted to a roller in the present invention. The absorbing material  21  is well-known to those with ordinary skills in the art, and thus the description thereof is not presented. 
         [0047]    The regenerating portion  22  is dispose on one side of the absorbing material  21 . The regenerating portion  22  uses plasma to ionize the circulating gas flow  91  so that the ionized circulating gas flow  91  desorbs the moisture absorbed by the absorbing material  21 . In the present embodiment, the regenerating portion  22  comprises a housing  222  capable of allowing the circulating gas flow  91  to pass through. The housing  222  covers part of the absorbing material  21  so that the ionized circulating gas flow  91  in the housing  222  passes through the absorbing material  21  to desorb the moisture in the absorbing material  21 . 
         [0048]    In order to accelerate the dehumidified gas flow  90  to better control dehumidification, the dehumidifier  2  of present embodiment further comprises a dehumidifying blower  24  capable of exhausting the dehumidified gas flow passing through the absorbing material  21  out of the dehumidifier  2 . Moreover, the dehumidifier  2  further comprises a heating unit  23 . In the present embodiment, the heating unit  23  is disposed between the inlet  220  of the regenerating portion and the condenser plate  201 . The heating unit  23  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. 
         [0049]    Several embodiments of the regenerating portion of the present invention are described hereinafter. Please refer to  FIG. 4A , which is a schematic diagram of a regenerating portion according to a first embodiment of the present invention. In the present embodiment, the regenerating portion  22  comprises a pair of electrodes  223  and  226  and a pair of insulators  224  and  225 . The pair of electrodes  223  and  226  comprise a conductive material and are disposed respectively on both sides of the absorbing material  21 . Each of the electrodes  223  and  226  comprises a plurality of gas channels to allow the circulating gas flow to pass through. The pair of insulators  224  and  225  are connected respectively to the pair of electrodes  223  and  226  to prevent the pair of electrodes  223  and  226  from being short-circuited during discharge. In  FIG. 4A , a gap  228 / 229  is formed between each of the insulators  224  and  225  and the surface of the absorbing material  21 . In the present embodiment, the gap  228 / 229  (wherein discharge takes place) is smaller than 10 mm, preferably within a range from 0.1 to 5 mm, but not limited thereto. The insulators  224  and  225  are connected to the electrodes  223  and  226 , respectively, by wrapping the electrodes or contacting the electrode surfaces. Moreover, each of the insulators  224  and  225  comprises a plurality of insulating structures  2240 . Each of the insulating structures  2240  corresponds to one of the gas channels respectively. 
         [0050]    Please refer to  FIG. 4B , which is a 3-D view of an electrode and an insulator in  FIG. 4A . In  FIG. 4B , the electrode  223  is circular and has a plurality of holes  2230  as a gas flow channel. The diameter of each of the holes  2230  is within a range from 0.5 mm to 8 mm, but not limited thereto. 
         [0051]    The dehumidifier of the present invention operates as shown in  FIG. 3  and  FIG. 4A . The desorbed moisture is carried away from the absorbing material  21  by the circulating gas flow  91  to enter the condenser plate  210  to be condensed. The condensed moisture is then collected by a water collector  29 . After the condensed moisture is collected by the water collector  20 , the circulating gas flow  91  is driven by the regenerating blower  202  to enter the regenerating portion  22  through the pipeline to repeat the moisture desorption process. In  FIG. 3 , the gas flow  90  to be dehumidified passes through the condenser plate  201  to perform a heat exchange process with the circulating gas flow  91  in the condenser plate  201 . Then the heat-exchanged gas flow  90  is exhausted out of the dehumidifier  2  by the dehumidifying blower  24  after passing through the absorbing material  21 . Since the absorbing material  21  comprises dehumidifying structures  210  and a desiccative therein to absorb gas water molecules in the gas flow  90  to generate a dehumidified gas flow  92 . The absorbing material  21  with saturatedly absorbed moisture has to be regenerated by desorption before it is capable of absorbing moistures to dehumidify the air. 
         [0052]    In the previous embodiment, a current is conducted between the electrodes that do not contact the absorbing material. Alternatively, in the next embodiment, the electrodes are connected with the absorbing material so that a current is conducted between the electrodes to desorb a substance. Please refer to  FIG. 5 , which is a flowchart of a low power consumption desorption method according to second embodiment of the present invention. In the present embodiment, the method  4  comprises steps as described hereinafter. Firstly, in step  40 , an absorbing material is provided. The absorbing material is capable of absorbing organic volatile substances, nitrogen or moistures, but not limited thereto. 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. 
         [0053]    After step  40 , step  41  is performed. In step  41 , electrodes are provided on both ends of the absorbing material. In step  42 , a voltage is applied across the electrodes on the both ends of the absorbing material so that the absorbing material is conductive to perform desorption. In the present embodiment, the applied voltage is an AC voltage or a DC voltage. When the current passes through the absorbing material, the temperature rises to weaken the bond between the absorbed substance and the absorbing material. The current is induced due to ion hopping in the absorbing material, ion/proton transport in the ionized substance or both. If the absorbed substance is water, the water molecules help to increase the conductivity of the ions in the absorbing material. As a result, the heat loss is reduced and the power consumption is reduced because there is no need to heat up the atmosphere. Moreover, in step  42 , a gas flow may be applied so that the heat is delivered throughout the desorption region. With the heat delivered by the gas flow, the desorption rate is increased to improve the desorption efficiency of the absorbing material. In one embodiment, the gas flow is heated with higher temperature to improve the desorption efficiency of the absorbing material. 
         [0054]    Please refer to  FIG. 6 , which is a schematic diagram of a second embodiment of a low power consumption desorption apparatus of the present invention. In the present embodiment, the 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 at least a substance. The absorbing material  30  and the absorbed substance are as described previously and will not be repeated herein. 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 , a current can be induced through the absorbing material  30  to perform desorption. 
         [0055]    Taking a dehumidification wheel for example, in order to perform desorption only in some specific region in the absorbing material while remaining absorption in other region when the dehumidification wheel 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. 
         [0056]    Please refer to  FIG. 7A , 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 meshed metal electrode  310  and an insulating frame  311 . The meshed metal electrode  310  is made of a conductive material that is not limited. The meshed metal electrode  310  is provided with a metal frame  312  on the fringe so that the meshed metal electrode  310  can be flat and the metal frame  312  functions as a contact for contacting a brush  330  while rotating. The insulating frame  311  is disposed inside the meshed metal electrode  310  so that the meshed metal electrode  310  is divided into a plurality of desorption regions  313 . The insulating frame  311  does not only divide the meshed metal electrode  310  into a plurality of conductive regions but also strengthens the structure of the meshed metal electrode  310  and keeps the meshed metal electrode  310  flat. The adjacent desorption regions are insulated from one another due to the insulating frame  311 . When the brush  330  contacts the metal frame  312 , electric conduction occurs only in the desorption region where the metal frame  312  contacts while the other regions remain absorption. 
         [0057]    Please refer to  FIG. 7B , which is a cross-sectional view of an electrode and an absorbing material according to one embodiment of the present invention. A conductive layer  314  is provided between the meshed metal electrode  310  and the absorbing material  30  to reduce contact resistance and enable the current to be uniformly distributed. In the present embodiment, the conductive layer  314  comprises a silver paste or other conductive materials. Please refer to  FIG. 8 , which is a schematic diagram showing the operation of electrodes according to one embodiment of the present invention. The electrodes  31  and  32  are provided on both ends of the absorbing material  30 . When the absorbing material  30  rotates and the brush  30  contacts the metal frame  312 , the brush  30  contacts corresponding desorption region to cause electric conduction in the desorption region. 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. Referring to  FIG. 9 , a gas flow channel  34  is provided on both ends of the desorption region corresponding to the brush  330 . The gas flow channel  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. 
         [0058]    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. 
         [0059]      FIG. 10  shows the testing result of a dehumidifier. In  FIG. 10 , 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. 10 ). 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. 10 , 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. The values shown in  FIG. 10  are measured power consumption values divided by the amount of desorbed water. In  FIG. 10 , with the electrodes being applied with a voltage, the power consumption is 45% reduced (dropping from 7854 J/g to 4200 J/g). Even though the values in  FIG. 10  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. 
         [0060]    Accordingly, the present invention discloses a method and an apparatus for desorption and a dehumidifier using the method and the apparatus wherein a voltage is applied across electrodes on both ends of an absorbing material for desorption. Therefore, the present invention is useful, novel and non-obvious. 
         [0061]    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.