Patent Publication Number: US-2010107681-A1

Title: Heat exchanger and refrigeration cycle apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a heat exchanger for adsorbing water content in the air, and a refrigeration cycle apparatus having the same. 
     BACKGROUND ART 
     In a refrigeration cycle apparatus using a refrigeration cycle such as an air conditioning system and a refrigeration system, a compressor, a condenser (heat exchanger), an expansion valve, and an evaporator (heat exchanger) are basically connected with the pipe to form a refrigerant circuit for circulating a refrigerant such as a geotropic refrigerant mixture, a pseudo azeotropic refrigerant mixture, and a single refrigerant. Utilizing that the refrigerant absorbs and radiates heat against air subjected to the heat exchange upon evaporation and condensation, the air-conditioning and cooling operations are performed while changing the pressure of the refrigerant passing through a pipe. 
     The heat exchanger functioning as the evaporator and the condenser allows the refrigerant to pass through the pipe therein to perform heat exchange. Since in the heat exchanger serving as the evaporator, the low temperature refrigerant passes through the pipe to absorb the heat in the air, the water content (vapor) in the air is condensed on the surface of the pipe to be deposited thereon as frost. When the frost is deposited (formed), the frost exists between the refrigerant and air. The deposited frost narrows a gap through which air passes, thus interfering with the air flow. Heat exchange between the refrigerant and air cannot be appropriately performed, thus deteriorating operation efficiency. Therefore, defrosting for removing the frost adhered to the evaporator is performed on a regular basis, or when it is judged that efficiency is deteriorated. 
     The defrosting may remove the frost adhered to the evaporator, but consumes an extra energy, thus failing to improve the efficiency of the air conditioning system. Immediately after finishing the defrosting, the temperature in the freezer and refrigerator is increased although it is required to maintain a predetermined temperature range. In such a case, the load for cooling up to a required temperature range is increased, thus further consuming electric power, resulting in efficiency deterioration. 
     Meanwhile, in the case of such as an air conditioning system for cooling/heating, in the in-between period of cooling (rainy season, autumn) for example, a cooling load tends to be small. In such a case, an operation frequency of the compressor is usually controlled to decrease the flow rate of the refrigerant (per unit time) circulated in the refrigerant circuit. At this time, the evaporating temperature in the evaporator increases to remove a sensible heat. However, a latent heat (water content in the air (vapor)) may not be removed. If the latent heat in the room cannot be removed, the relative humidity in the air in the room will be increased, which cause discomfort of the person in the room to increase. 
     A device for removing the water content in the air has been disclosed to solve the aforementioned problem (for example, see Patent Document 1). The dehumidifying device uses zeolite which is a porous inorganic oxide, as a water adsorbing material (hereinafter referred to as an adsorbing material) for example, to make the fin for performing heat exchange between the air and refrigerant support it. 
     [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-353887 (FIG. 1) 
     DISCLOSURE OF INVENTION 
     Problems to be Solved by the Invention 
     In the aforementioned device, the thermal expansion may cause distortion between the fan and the adsorbing material, so that the adsorbing material may peel off to be contained in the air and dispersed. In the case where such device is employed in the freezer and refrigerator for storing foods, it is required to prevent the adsorbing material from being peeled off for quality control of foods. The aforementioned requirement may be applied to the heat exchanger for air conditioning in the living space. It is therefore difficult to control the heat exchanger using the adsorbing material. The loss in thermal conduction may lower the energy efficiency. 
     If the zeolite is employed as the adsorbing material on the surface of the desiccant rotor for removing a water content in the air which flows into the heat exchanger, the temperature required for desorption is high. Therefore, it is difficult to desorb the adsorbed water using the temperature of the refrigerant flowing through the refrigerant circuit and to re-use the water. 
     The present invention is made to solve the aforementioned problem, and an object of the present invention is to provide a heat exchanger and a refrigeration cycle apparatus such as an air conditioning device and refrigerator capable of more efficiently adsorbing water performing the heat exchange. 
     Means for Solving the Problems 
     A heat exchanger according to the present invention includes fins for heat transfer in the heat exchanger for exchanging heat between a refrigerant and air. The fin has fin pores on the surface for adsorbing the water in the air by capillary condensation. Each of the fine pores has a different diameter depending on the position on the surface of the fins. 
     Preferably the fine pores are in the range from 1 to 20 nm. The fin is made of a material which contains aluminum, titanium, zirconium, niobium, or tantalum. The fine pores are formed by an anodic oxidation method. After forming recess portions at predetermined intervals on the material to be the fin, fin pores can be formed by the anodic oxidation method. 
     Advantages 
     The fine pores are formed on the surface of the fin of the heat exchanger such that the fin itself functions as the water adsorbing unit using the capillary condensation phenomenon. The heat exchanger capable of making the fins adsorb water contained in air in the subject space may be provided without requiring special means and materials. The peeling-off of the supported adsorbing member never occurs, thus it is safe from the viewpoint of sanitation and easy to manage. No pressure loss of air caused by the adsorbing material occurs, so that efficient heat exchange can be performed in view of the energy consumption. Since it is not necessary to provide adsorbing material, the apparatus can be made compact. By making each diameter of the fine pores different depending on the position on the fin surface, it is possible to obtain the heat exchanger appropriately performing adsorption/desorption while being suitably adapted to the environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration view showing an essential portion of the structure of a heat exchanger according to Example 1. 
         FIG. 2   a  is a view showing a relationship between the fine pore diameter of the fin which forms the heat exchanger and the relative humidity. 
         FIG. 2   b  is a view schematically showing how the water being adsorbed in the fine pore. 
         FIG. 3  is a view showing characteristics of the fine pore diameter and adsorption. 
         FIG. 4  is a view showing an example of the water adsorbing characteristics of the fine pores on the surface of a fin  45 . 
         FIG. 5  is an enlarged view of the surface of the fin  45 . 
         FIG. 6  is a structural view showing the heat exchanger having a fine-pores distribution of along an air flow direction (column direction). 
         FIG. 7   a  is a view showing the relationship between the air flow direction (column direction) and the relative humidity. 
         FIG. 7   b  is a view showing the relationship between the air flow direction and the adsorption amount. 
         FIG. 8   a  is a view showing the relationship between the air flow direction (column direction) and the relative humidity. 
         FIG. 8   b  is a view showing the relationship between the air flow direction and the desorption amount. 
         FIG. 9   a  is a view showing the method for manufacturing the fin having fine pores with the same diameter. 
         FIG. 9   b  is a view showing the method for manufacturing the fin having fine pores with a different diameter. 
         FIG. 10  shows operation points on the psychrometric diagram. 
         FIG. 11  schematically shows an exemplary structure of a refrigeration cycle apparatus according to Embodiment 4. 
         FIG. 12  is a relationship view showing a relationship between the evaporating temperature and COP. 
         FIG. 13  is a schematic view showing an exemplary structure of the refrigeration cycle apparatus according to Embodiment 5. 
         FIG. 14  is a schematic view three-dimensionally showing a humidifying unit of the refrigeration cycle apparatus. 
         FIG. 15  is an illustrative view showing the state where an air passage in an indoor unit is switched. 
         FIG. 16  is a P-h diagram showing the state of the refrigerant in the refrigeration cycle. 
         FIG. 17  is a psychrometric diagram for explaining the operation of the refrigeration cycle apparatus. 
         FIG. 18  is a schematic view showing an exemplary structure of the refrigeration cycle apparatus according to Embodiment 6. 
         FIG. 19  is a schematic view showing the structure of the indoor unit having a built-in evaporator. 
         FIG. 20  is an illustrative view showing the state where the air passage in the indoor unit is switched. 
         FIG. 21  is a P-h diagram showing the state of the refrigerant in the refrigeration cycle. 
         FIG. 22  is a psychrometric diagram for explaining the operation of the refrigeration cycle apparatus. 
         FIG. 23  is a schematic view showing an exemplary structure of the refrigeration cycle apparatus according to Embodiment 7. 
     
    
    
     REFERENCE NUMERALS 
     
         
         
           
               1 ,  1   a ,  1   b ,  1   c ,  1   d  refrigerant pipe 
               2 ,  2   a ,  3 ,  3   a  bypass pipe 
               10  compressor 
               20  condenser 
               30 ,  31 ,  32 ,  33 ,  34 ,  35 ,  36 ,  37  on-off valve 
               38 ,  39  three-way valve 
               40  heat exchanger 
               40   a  heat exchanger with distributed fine pores 
               41 ,  41   a ,  41   b ,  41   c ,  41   d ,  41   e ,  41   f  heat exchanger for dehumidification/humidification 
               45  fin 
               45   a  fine pores 
               45   b  porous layer 
               45   c  barrier layer 
               45   aa  fin at the first column 
               45   ab  fin at the second column 
               45   ac  fin at the third column 
               46  heat transfer pipe 
               50 , 51  back-flow prevention member 
               60 ,  61 ,  62 ,  63 ,  64 ,  85  throttle device 
               70  evaporator 
               80 ,  80   a ,  80   b  control unit 
               81  temperature/humidity detection unit 
               90 , 91  blower 
               100 ,  100   a ,  100   b ,  100   c  refrigeration cycle apparatus 
               300 , 300   a  indoor unit 
               301   a ,  301   b ,  302   a ,  302   b ,  303   a ,  303   b ,  304   a ,  304   b ,  311   a ,  311   b ,  312   a ,  312   b ,  313   a ,  313   b ,  314   a ,  314   b  air passage switching unit 
               305   a ,  305   b ,  315   a ,  315   b  air passage switching unit 
               400  refrigerated warehouse 
               401  interior 
               500  external air 
               610  dc power source 
               620  electrolyte 
               630  electrolyte vessel 
               640  carbon electrode 
               650  fin 
           
         
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Embodiment 1 
       FIG. 1  shows an essential portion of a heat exchanger  40  according to Embodiment 1 of the present invention. The structure of the heat exchanger  40  as the featuring part of the present invention will be described referring to  FIG. 1 . The heat exchanger of a fin tube type which has been widely used for the refrigerator and air conditioning system will be explained as an example. 
     The heat exchanger  40  is mainly composed of plural fins  45  for heat exchanger (hereinafter referred to as a fin  45 ), and plural heat transfer pipes  46 . The fin  45  of the present embodiment is a flat plate made of the material with a high thermal conductivity (thermal conductivity: approximately 230 W/mK) such as aluminum. The fin  45  has fine pores on the surface as described later. The plural fins  45  are laminated at a predetermined interval. The heat transfer pipes  46  are provided, for example, at a predetermined interval so as to penetrate through holes formed in each fin  45 . Each heat transfer pipe  46  becomes part of a refrigerant circuit, allowing the refrigerant to flow therethrough. The heat of the refrigerant flowing through the heat transfer pipe  46  and the heat of the air flowing outside are transferred via the fins  45  to expand the heat transfer area, thus the heat exchange between the refrigerant and the air is efficiently performed. The path of the heat transfer pipes  46  in the heat exchanger  40  is not especially limited. For example, the flow path may be formed to be branched to allow the refrigerant to flow into the plural heat transfer pipes  46  which penetrate the fins  45 , and then to be joined. The refrigerant flow path may also be formed to make the laminated fins  45  bent at the end of the heat exchanger  40  or connected by the bent pipe reciprocated. Referring to  FIG. 1 , the heat transfer pipes  46  penetrate the fins  45  at 6 points, however, the number of the heat transfer pipes  46  is not limited thereto. 
     The fin  45  is made of materials containing aluminum, titanium, zirconium, niobium, or tantalum, and includes a plurality of fine pores having diameters ranging from 1 to 20 nm. The fine pores of the fin  45  may be formed by the anodic oxidation method. The fine pores may be formed by the anodic oxidation method after forming recesses at a predetermined interval in the material for forming the fin  45  in advance. 
       FIG. 2   a  is a view showing the relationship between the diameter (hereinafter referred to as fine pore diameter) of the fine pores of the fin  45  and the relative humidity at which the capillary condensation occurs. The horizontal axis represents the fine pore diameter [nm (nanometer)], and the vertical axis represents the relative humidity [%] of the air in the subject space (assuming that current humidity is P, and saturated humidity at the current humidity being PO, the relative humidity may be expressed as P/PO).  FIG. 2   a  shows a graph calculated based on the formula of Kelvin. 
     
       
         
           
             
               
                 
                   
                     Relative 
                      
                     
                         
                     
                      
                     
                       humidit 
                        
                       y 
                     
                      
                     
                       : 
                     
                      
                     
                         
                     
                      
                     
                       P 
                       
                         P 
                         0 
                       
                     
                   
                   = 
                   
                     exp 
                      
                     
                       ( 
                       
                         - 
                         
                           
                             2 
                              
                             
                               v 
                               1 
                             
                              
                             γcos 
                              
                             
                                 
                             
                              
                             θ 
                           
                           rRT 
                         
                       
                       ) 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Formula 
                      
                     
                         
                     
                      
                     1 
                   
                   ] 
                 
               
             
           
         
       
     
     Here, v 1  denotes a condensed molecule volume, γ a surface tension, θ an angle when in contact with capillary, R a gas constant (8.31[J/mol° K]), T the absolute temperature, and r the radius of the fine pore. The relationship may hold in the case of water vapor. So, the radius r of the fine pore required for water vapor to cause capillary condensation may be theoretically obtained for a certain relative humidity P/PO. 
     As shown in  FIG. 2   a , capillary condensation (a phenomenon in which the vapor (water content) inside the fine pore is liquefied) occurs at the relative humidity corresponding to the fine pore diameter. In  FIG. 2   a , water molecules may be maintained in the fine pore in the zone A, while water molecules cannot be maintained in the fine pore in the zone B. That is, the water content in the air may be adsorbed in the zone A. On the contrary, the water content can be removed from the fine pore by making the air conditions of the zone B. 
       FIG. 2   b  shows the image of adsorption of water into the fine pore. As shown in  FIG. 2   b , water is gradually adsorbed into the fine pore. The equilibrium adsorption amount may be sharply increased (changed) at the boundary of the predetermined narrow range in the vicinity of the relative humidity when a number of fine pores having the diameter in accordance with the relative humidity uniformly are formed. 
     The relationship between the fine pore diameter and the adsorption isothermal may be obtained in reference to  FIG. 2   a .  FIG. 3  is a characteristic view showing the relationship between the water content (adsorbing characteristics) of the fine pore diameter of the fin  45  according to Embodiment 1 of the present invention and the relative humidity showing a sharp change (hereinafter referred to as rising edge). As shown in  FIG. 3 , the relative humidity at the rising edge becomes relatively low by making the fine pore diameter of the fin  45  relatively small (line (a) in  FIG. 3 ). On the other hand, the relative humidity at the rising edge becomes relatively high by making the fine pore diameter large (line (b) in  FIG. 3 ). 
     For example, the adsorbing material may demonstrate the rising edge feature at the relative humidity of approximately 30% as shown by the line (c) in  FIG. 3  by setting the fine pore diameter d at 2.0 nm. The adsorbing material may demonstrate the sharp rising edge feature at the relative humidity of approximately 90% by setting the fine pore diameter of 20 nm. Adsorbing characteristics of the fin  45  may be freely controlled using  FIG. 3 . 
     Since the adsorbing material is used for the fin  45  for the purpose of dehumidification, an upper limit of the relative humidity is less than 100%. The line (b) shown in  FIG. 3  indicating a sharp rising edge at the relative humidity of approximately 90% is an upper limit value of the adsorbing characteristics, and the fine pore diameter is approximately 20 nm. Therefore, when used for the air-conditioning device (including the refrigerator), the upper limit of the fine pore diameter of the fin  45  is set at 20 nm. 
     In the manufacturing, selection of the fine pore diameter in accordance with the usage may reduce the production volume to increase the cost of the adsorbing material. Since the fine pore of nano scale is invisible to human eyes, it is not possible to identify the fin with a different fine pore diameter. As a result, there may be a risk of mounting the adsorbing material with improper fine pore diameter on the product, resulting in a poor quality. Therefore, it is preferable to consolidate the fine pore diameter of the adsorbing material to one kind in view of the cost and quality. However, in order to be effective as the fin  45  for dehumidification, the fine pore diameter have to be consolidated into a fine pore diameter capable of dehumidification in the most usages (most humidity conditions). 
     Table 1 shows an example of the fine pore diameters (relative humidity) required for the respective usages. Table 1 shows the relative humidity in the subject space and the fine pore diameter of the fin  45  required for the relative humidity. Table 1 is quoted from the collection of papers of “Latest humidity control technology” in the lecture meeting of Japan Society of Refrigerating and Air conditioning Engineers (pp. 5-6, published on May 25, 2005). 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Fine pore 
                 Relative humidity 
               
               
                   
                 Field 
                 diameter [nm] 
                 condition [%] 
               
               
                   
                   
               
             
            
               
                   
                 Fruits and vegetables 
                  6-20 
                 70-95 
               
               
                   
                 Stock farm products 
                  4-20 
                 65-95 
               
               
                   
                 Pharmaceutical factory 
                 2-4 
                 40-50 
               
               
                   
                 Library 
                 2-4 
                 40-50 
               
               
                   
                 Art museum/museum 
                 2-5 
                 40-55 
               
               
                   
                 Photographic plant 
                 1-6 
                 24-70 
               
               
                   
                 Human 
                 1-2 
                 20-30 
               
               
                   
                   
               
            
           
         
       
     
     For example, in the warehouse for storing fruits and vegetables, the relative humidity is required to be in the range from approximately 70 to 95%, therefore, the fine pore diameter may be set so that the relative humidity sharply rises at approximately 70 to 95% in the adsorbing characteristics shown in  FIG. 2   a . That is, the fine pore diameter of the adsorbing material may be designed to be 6 to 20 nm in reference to  FIG. 2   a  (showing the relationship between the fine pore diameter and capillary phenomenon). In an air conditioned space (living space for the human), the relative humidity is generally said to be kept in the range from 20 to 30% or higher. 
     Generally, the lower limit value of the relative humidity is considered to be in the range from approximately 20 to 30% except for a special usage. Accordingly, the use of the fin  45  with the adsorbing characteristics (the fine pore diameter is in the range from approximately 1.0 nm to 3.5 nm) which sharply rises at the relative humidity around 20% to 50% as shown in  FIG. 3  may cover almost all the usage (wide range). Increase of the use of the fin  45  having the same specification (the same fine pore diameter) may produce a mass production effect to reduce the cost of the fin  45 , thus improving the manufacturing quality. 
     The refrigeration cycle of the refrigerator is designed to have the condensation pressure corresponding to the condensation temperature of approximately 65° C. Because of the restriction, in the condenser, the air of an external air side  100   a  is heated up to about 65° C. So that, it is realistic to think that a lower limit value of the relative humidity produced by the exhaust heat of the condenser of the refrigeration cycle be approximately 10% (an external air of 32° C. and the relative humidity 60% is heated up to 65° C. and the relative humidity 10%). The fine pore diameter at that time is approximately 1 nm by  FIG. 2   a . Accordingly, the lower limit of the fine pore diameter of the fin  45  for dehumidification is made to be 1 nm. 
       FIG. 4  is a view showing an example of the water adsorbing characteristics of the fine pore formed on the surface of the fin  45 . Next, the fine pore formed on the surface of the fin  45  will be described.  FIG. 4  shows the adsorption isothermal of the fine pore with the diameter of approximately 2 nm. The horizontal axis represents the relative humidity [%] of the air in the space to be cooled, and vertical axis represents the water content (adsorbed water amount/weight of fin  45 , which is proportional to the equilibrium adsorption amount). 
     As shown in  FIG. 4 , the fin  45  capable of adsorbing water at the relative humidity of approximately 30% or higher no longer keeps adsorbing the water when the relative humidity is decreased to approximately 30% or lower. Therefore, the adsorbed water may be desorbed by lowering the relative humidity to approximately 30% or smaller. 
       FIG. 5  is an enlarged view of the surface of the fin  45 . In the present embodiment, as described above, the fine pores  45   a  for adsorbing/desorbing the water are formed on both surfaces of the fin  45  simultaneously using the anodic oxidation (anodization). When performing a direct current electrolysis under the environment of in the acidic solution such as sulfuric acid, oxalic acid, phosphoric acid, chromic acid, and alkaline solution such as sodium phosphate with the fin (aluminum) being an anode, the aluminum ion (Al 3+ ) dissolved from the fin (aluminum) reacts with the water (H 2 O) to generate an aluminum oxide (alumina) film (hereinafter, referred to as the anodic oxide film) on the aluminum, which is a substrate metal. Here, the fine pore  45   a  may be formed by a through hole, because an effect remains unchanged that the fine pore  45   a  can adsorb/desorb water even if it is a through hole. 
     The anodic oxide film is formed of a porous layer  45   b  where the vertical fine pore  45   a  is formed and a barrier layer  45   c  at the bottom wall portion in contact with the substrate metal, having a so-called hexagonal cell structure. When forming the fine pore  45   a , since the thickness of the barrier layer  45   c  is basically kept constant, the depth of the fine pore  45   a  may be controlled by substantially controlling the film thickness. Since the film forming rate and film thickness depend on the current or potential to be supplied between the both electrodes and the anodic oxidation period, the current or potential to be supplied between the both electrodes and the anodic oxidation period are controlled when forming the fine pore  45   a  with a predetermined depth. Since the number of fine pores per unit area (density) and the fine pore diameter depend on the potential between the both electrodes, the potential therebetween is controlled so as to form a predetermined number and diameter of the fine pores. A mold (metal mold) having protrusions formed at an interval corresponding to that of the fine pores  45   a  is pressed against an aluminum surface, which is to be a fin  45 , to form regular recess portions on the surface. Thereafter, when the anodic oxidation is conducted, the fine pores  45   a  are formed centering around the recess portion, so that the fine pores  45   a  are regularly arranged and it is possible to perform high accuracy control on a surface with a constant density. In order to prevent the fine pore  45   a  formed by the anodic oxidation from reacting with the water contained in air to be blocked, the fin  45  is heated by hot air at the temperature 100 to 200° C. immediately after the formation of the fine pores to remove the water contained in the film to perform an operation of changing into a stable oxide. The heat transfer pipes  46  are inserted into the thus formed plural through holes of the fins  45  to make the heat exchanger  40 . 
     In Embodiment 1, the fine pores are formed on the surface of the fin  45  of the heat exchanger  40  and the fin  45  is made to function as water adsorbing member, so that it is possible to make the water in the air in the subject space adsorb without requiring the special member and materials. Thus, the adsorbing material can be prevented from peeling off due to the distortion caused by the temperature swing between adsorbing materials having different heat expansion coefficients. Since no thermal resistance exists between the fin  45  and the adsorbing material such as silica gel, the heat transfer efficiency may be improved. The thermal conductivity of the silica gel is small, such as approximately in the range from 0.05 to 0.17 W/mK, so that the heat transfer efficiency may be deteriorated. However, since direct heat exchange can be performed between the fin  45  with good thermal conductivity and the air, the heat exchange between the air and the refrigerant can be more efficiently conducted. 
     The fin  45  does not have to be thick to accommodate the adsorbing material so that the interval between the fins  45  of the heat exchanger  40  may be increased. As a result, the pressure loss of the flowing air is reduced, so that the input of the fan for making the air flow into the heat exchanger  40  can be decreased. Even if the interval is not changed, the heat exchanger  40  may be made compact by the amount corresponding to the thickness of the adsorbing material. Since the fine pores with a fine pore diameter within the range from approximately 1 to 20 nm in accordance with the relative humidity are arranged to be formed on the surface of the fin  45 , the adsorbed water may be desorbed and reproduced (making the water adsorbed again) using the heat (exhaust heat) of the refrigerant flowing in a common refrigeration cycle apparatus. 
     The fine pores having a regular pattern are formed by the anodic oxidation method vertically to the surface of the fin  45 . Therefore, unlike the adsorbing material with the fine pores arranged in no regular pattern, for example, the flow directionality of the adsorbed water may be aligned to efficiently transfer the heat of the fin  45 . 
     Example 2 
       FIG. 6  is a configuration view showing an essential portion of a heat exchanger  40   a  according to Embodiment 2 of the present invention. In  FIG. 6 , fins  45   aa ,  45   ab ,  45   ac  are made to have fine pores with different diameters for each column along the air flow direction. That is, against the air flow direction upon the adsorption, the fine pore diameter at an upwind side is made large, and that at a downwind side is made small. Therefore, in the case of  FIG. 6 , the fine pores are distributed in such an aspect that fine pore diameter on the first column  45   aa &gt;fine pore diameter on the second column  45   ab &gt;fine pore diameter on the third column  45   ac.    
       FIG. 7   a  shows a simulated result of the relative humidity distribution of the air flow direction (column direction of the heat transfer pipe) of the heat exchanger using fins having the same fine pore diameter. The water content of the fin  45  has a feature to rise up at the relative humidity of approximately 30%. From the heat transfer pipe at the upwind side upon the adsorption, it is referred to as the first and the second, and the third columns. As can be understood from  FIG. 7   a , as the air flows from the upwind side to the downwind side, the water is adsorbed by the fin  45 , so that the relative humidity around the fin is decreased. 
     Meanwhile, the embodiment according to the present invention employs the fin which has the fine pore distribution with different fine pore diameters along the flow direction. That is, viewing from the upwind side, the fine pore diameter on the second column is smaller than that on the first column, and the fine pore diameter on the third column is smaller than that on the second column. The fine pore diameters of the fin  45  is changed for each column. The number of the columns is not especially limited, though, as the number of the columns is increased, the diameter of the fine pores distributed on the fin may be gradually changed. 
     For example, the fin  45   aa  on the first column has the fine pores diameter for which the water content rises at the relative humidity of approximately 50% (3.5 nm), the fin  45   ab  on the second column at the relative humidity of approximately 40% (2.5 nm), and the fin  45   ac  on the third column at the relative humidity of approximately 30% (2 nm). The change in the adsorption amount with respect to the air flow direction (column direction) is shown in  FIG. 7   b . As can be understood from  FIG. 7   b , the total adsorption amount of the fin with the fine pores made to have a distribution along the column direction is larger than that of the fin having the same fine pores diameter. So that the fin may be effectively used. 
     In the case of the fin having the same fine pores diameter, the more downstream side the fin is located, the smaller the difference becomes between the relative humidity of air around the fin and the relative humidity 30%, where the water content of the fin rises. So that the adsorbing speed of the fin is reduced, and resultantly, the adsorption amount decreases toward the downstream side. 
     The fin having the fine pores of relatively larger diameter may be employed, so that it is possible to reduce the total cost of the fin. (the larger the fine pore diameter becomes, the less manufacturing period, and accordingly, the production cost may be reduced). 
       FIG. 8   a  shows the relative humidity to the air flow direction upon desorption when using the fin with fine pores having the same diameter. The air flow direction is reversed to that upon adsorption. While on desorption, the fin at the third column is at the upwind side, on adsorption it is at the downwind side. From  FIG. 8   a , it is found that the relative humidity around the fin becomes larger toward the downwind side. 
     The embodiment according to the present invention employs the fins having a fine pore distribution making the fine pore diameter changed along the flow direction. For example, the fin  45   aa  on the first column has the fine pore diameter for which the water content rises at the relative humidity of approximately 50% (about 3.5 nm), the fin  45   ab  on the second column the relative humidity of approximately 40% (about 2.5 nm), and the fin  45   ac  on the third column the relative humidity of approximately 30% (about 2 nm), respectively. As shown in  FIG. 8   b , the fine pore distribution in the column direction provides a larger desorption amount in total compared with the use of the fin having the fine pores of the same diameter, resulting in the effective use of the fin. In the case of the fins having the fine pores of the same diameter, the difference between the relative humidity of air around the fin and the relative humidity 30%, where the water content around the fin  45  rises, becomes smaller toward the downstream side to decelerate adsorbing rate of the fin, an desorption amount is decreased toward the downwind side. 
     The distribution of the fine pores diameter of the fin  45  formed along the column direction allows effective use of the fin  45  to improve the adsorption/desorption performance. Resultantly, it is possible to make the heat exchanger compact. 
     When the fin includes two columns ( FIG. 1  shows two columns, however, three or more columns may be possible) as shown in  FIG. 1 , the relative humidity is lowered at the downwind side, it is preferable to set the fine pore diameter to be relatively smaller. As shown in  FIG. 7   a , the relative humidity around the fin adjacent to the outlet is approximately 35%. The fine pore diameter may be set to approximately 1 to 3.5 nm because the fin is required to have characteristics in which the water content abruptly rises at the relative humidity of about 20 to 40%. 
     In the description, the fine pore diameter of the fin at the downwind side with respect to the air flow direction in the water absorption is smaller than the fine pore diameter of the fin at the upwind side. However, the fine pore diameter of the fin at the downwind side with respect to the air flow direction in the water absorption may be larger than that of the fin at the more downwind side than that so far as the fine pore diameters are different for each column and in the range approximately from 1 to 3.5 nm. For example, when the fine pore diameter of the fin outside the heat exchanger may be set to be larger than the fine pore diameter of the fin inside the heat exchanger, it is possible to perform efficient dehumidification by making the air in contact with the heat exchanger flow from two directions rather than a single direction. 
     A method for manufacturing the heat exchanger having a fine pore distribution using an anodic oxidation method will be briefly described. As shown in  FIG. 9   a , a three-column fin  650  is collectively submerged in an electrolysis vessel  630  to form a fin having homogeneous fine pores. Meanwhile, each column of the fin  650  is submerged to form predetermined fine pores as shown in  FIG. 9   b  when manufacturing the heat exchanger having fine pore distribution along the column direction. The anodic oxidation is conducted three times under the different conditions to produce three fins having different fine pores. Thereafter, the heat transfer pipes  43  are inserted for each column to be finally combined together by connecting a U-type pipe for providing the three-column heat exchanger. In  FIGS. 9(   a ) and  9 ( b ), reference numerals  610 ,  620  and  640  denote a direct current power supply, an electrolyte, and a cathode, respectively. 
     The effect derived from operating the heat exchangers  40 ,  40   a  using the fins with fine pores while being cooled with the refrigerant supplied thereto will be described.  FIG. 10  shows operations on the psychrometric diagram when the refrigerant is supplied to the heat exchanger and when the refrigerant is not supplied. At the inlet of the heat exchangers  40  and  40   a , the dry-bulb temperature, the relative humidity, the absolute humidity, and the dew point of air are 25° C., 60%, 0.0119[kg/kg], and 16.7° C., respectively. In the case where the refrigerant is not supplied, the relative humidity is lowered while the air temperature is increased by the adsorbing heat to finally become the air of the state (b)(dry-bulb temperature: 32.2° C., relative humidity: 30%, absolute humidity: 0.0119 kg/kg, and dew point: 12.44° C.). Meanwhile, in the case where the heat exchanger  40  is operated while cooling with the refrigerant supplied thereto, the refrigerant removes the adsorbing heat to substantially realize isothermal adsorption to finally become the state (c) (dry-bulb temperature: 25° C., relative humidity: 30%, absolute humidity: 0.0058 kg/kg, and dew point: 6.24° C.) 
     The difference in the absolute humidity for the case where the refrigerant is supplied and the case where the refrigerant is not supplied shows that the absolute humidity difference in the case where the refrigerant is supplied is twice higher than the absolute humidity difference in the case where the refrigerant is not supplied (absolute humidity difference when the refrigerant is not supplied: 0.0029[kg/kg], absolute humidity difference when the refrigerant is supplied: 0.00601[kg/kg]). That is, adsorption conducted while supplying the refrigerant to the heat exchangers  40 , 40   a  may largely improve the absorbing performance. The isothermal adsorption allows the dew point to be decreased from 12.44° C. to 6.24° C., thus applicable for use at the low dew point. 
     By preparing the fine pores which cause the capillary condensation on the fin of the heat exchanger, and supplying the refrigerant to the heat transfer pipes  46 , it is possible to provide a latent heat exchanger having the largely improved adsorbing performance. 
     Embodiment 3 
     In the above Embodiment 1, the fin  45  is made of aluminum, however, the material is not limited to the aluminum. For example, the so-called valve metal may be used as the material of the fin  45  to form fine pores on the surface through the anodic oxidation. The valve metal refers to a generic name of a metal which forms an oxide film showing an electrolytic rectifying operation through the anodic oxidation such as aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth and antimony. Among them, metals such as aluminum, titanium, zirconium, niobium, and tantalum may be practically used as the fin  45 . The use of those metals may provide the same effect as aluminum. 
     Embodiment 4 
       FIG. 11  shows an exemplary structure of a refrigeration cycle apparatus  100  according to Embodiment 4 of the present invention. The basic structure of the refrigerant circuit composed by the refrigeration cycle apparatus  100  will be described based on  FIG. 11 . The refrigeration cycle apparatus  100  is operated for cooling, refrigerating, and air conditioning by circulating the refrigerant. 
     The refrigeration cycle apparatus  100  is formed by sequentially connecting the compressor  10 , the condenser  20 , the first throttle device  60 , the heat exchanger  41  for dehumidification/humidification, the second throttle device  61 , and the evaporator  70  with a refrigerant pipe  1 . Here, the explanation will be given on the assumption that the compressor  10  and the condenser  20  are built into an outdoor unit (unit at the heat source side) which is disposed outside the space to be cooled/air-conditioned, and the first throttle device  60 , the heat exchanger  41  for dehumidification/humidification, the second throttle device  61 , and the evaporator  70  are built into the indoor unit (unit at the load side) disposed inside the subject space. Here, the condenser  20  is disposed at the outdoor unit, and the evaporator  70  is disposed at the indoor unit for explaining such operations for cooling and air-conditioning, however, these roles will be switched in the case of the heating operation. The switching is performed by the control unit for controlling a four-way valve (not shown). 
     The refrigerant pipe  1  includes a refrigeration pipe at the gas side which allows communication of a gaseous refrigerant, and the refrigeration pipe at the liquid side which allows communication of the liquid refrigerant. The refrigeration pipe at the liquid side communicates the refrigerant which has been condensed and liquefied, and the refrigeration pipe at the gas side communicates the refrigerant which has been evaporated and gasified. A blower (not shown) such as the fan for feeding air outside the subject space (hereinafter, referred to an external air) into the condenser  20  to promote heat exchange is disposed around the condenser  20 . A blower (not shown) such as the fan is also disposed around the evaporator  70 . The refrigerant to be enclosed into the refrigerant pipe  1  will be described later. 
     The compressor  10  sucks and compresses the refrigerant into a gaseous state of high temperature/pressure to supply to the refrigerant pipe  1 . The condenser  20  is a heat exchanger to perform heat exchange between the refrigerant and external air to condensate/liquefy the refrigerant. The first throttle device  60  is generally composed of a decompression valve and an expansion valve such as an electronic expansion valve for decompressing and expanding the refrigerant. 
     The heat exchanger  41  for dehumidification/humidification is composed of the heat exchangers  40 ,  40   a  (hereinafter represented by the heat exchanger  40 ) as described in Embodiments 1 to 3, having fine pores on the surface of the fin  45 . The description will be given, not limited to, on the assumption hereinafter that the heat exchanger  41  for dehumidification/humidification includes the fine pores with diameters for increasing the adsorption amount at the relative humidity of approximately 30% to desorbe the adsorbed water. The heat exchanger  41  for dehumidification/humidification mainly as an apparatus to remove the latent heat so as to supply air within the dehumidified subject space (hereinafter referred to simply the air) to the evaporator  70  by adsorbing the water. It is not limited to the usage, however, humidification unit may be disposed in the refrigeration cycle apparatus  100  to humidify the subject space using the heat exchanger  41  for dehumidification/humidification. 
     The second throttle device  61  is generally composed of the decompression valve and the expansion valve such as the electronic expansion valve to decompress and expand the refrigerant. The evaporator  70  evaporates and gasifies the refrigerant through the heat exchange between the refrigerant and the air. The blower disposed adjacent to the evaporator  70  sucks the air and supplies the cooled air through the heat exchange in the evaporator  70  to a region to be cooled (interior space, in the refrigerator, and refrigerated warehouse). For example, the control unit  80  composed of such as microcomputers controls the drive frequency of the compressor  10 , and opening of the first throttle device  60  and the second throttle device  61 . In the embodiment, description is given as a single control unit  80 , however, the control units may be provided for both the outdoor unit and the indoor unit, respectively and each controller controls the apparatus (unit) that each unit possesses. Thereby, an associated control is possible by enabling signal communication. 
     The refrigerant used for the refrigeration cycle apparatus  100  will be described. As for the refrigerant used for the refrigeration cycle apparatus  100 , there are the zeotropic refrigerant mixture, the quasi-azeotropic refrigerant mixture, and the single refrigerant. Regarding the zeotropic refrigerant mixture, there is such as R407C (R32/R125/R134a), which is an HFC (hydrofluoro carbon) refrigerant. Since the zeotropic refrigerant mixture is a mixture of refrigerants having different boiling points, it has characteristics that composition ratios of the liquid-phase refrigerant and gas-phase refrigerant are different. For the quasi-azeotropic mixture refrigerant, there are such as R410A (R32/R125), R404A(R125/R143a/R134a), that are HFC refrigerants. 
     The single refrigerant has the type R22 as the HCFC (hydro chlorofluorocarbon) refrigerant, and R134a as the HFC refrigerant. The single refrigerant has characteristics that it is not a mixture, so that it may be easily handled. Such natural refrigerants as carbon dioxide, propane, isobutene, and ammonia may also be employed. The R22, R32, R125, R134a, and R143a denote chlorodifluoromethane, difluoromethane, pentafluoroethane, 1,1,1,2-tetrafluoroethane, and 1,1,1-trifluoroethane, respectively. Accordingly, the refrigerant suitable for the usage and object of the refrigeration cycle apparatus  100  may be employed. 
     The operation of the refrigeration cycle apparatus  100  will be described. The heat exchanger  41  for dehumidification/humidification will be described with respect to the operation for adsorbing the water in the air. The refrigerant of high temperature/pressure compressed by the compressor  10  is condensed/liquefied to be the liquid refrigerant while releasing heat through the heat exchange with the external air in the condenser  20 . The liquid refrigerant flows into the first throttle device  60  and decompressed therein to become the low pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant having the temperature lower than the air flowed into the heat exchanger  41  for dehumidification/humidification is made to cool the fin  45  and air passing therearound through the heat exchange, and part of the air is evaporated and discharged. At this time, the fin  45  adsorbs the water of the passing air. The gas-liquid two-phase refrigerant discharged from the heat exchanger  41  for dehumidification/humidification passes through the fully opened second throttle device  61  to flow into the evaporator  70 . All the gas-liquid two-phase refrigerant is evaporated/gasified through the heat exchange in the evaporator  70  to be a gaseous refrigerator, and sucked by the compressor  10  again and discharged. 
     The operation of the heat exchanger  41  for dehumidification/humidification to desorb the adsorbed water will be described. The refrigerant of high temperature/pressure compressed by the compressor  10  becomes the gas-liquid two-phase refrigerant while releasing the heat to the external air in the condenser  20 . The gas-liquid two-phase refrigerant under the high pressure state passes through the fully opened first throttle device  60  and flows into the heat exchanger  41  for dehumidification/humidification. The gas-liquid two-phase refrigerant having the higher temperature than the air flowed into the heat exchanger  41  for dehumidification/humidification heats to liquefy the fin  45  and the ambient air. The liquefied refrigerant is decompressed by the second throttle device  61  to become the low pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant flows into the evaporator  70 , evaporated and gasified entirely into the gaseous refrigerant, and arranged to be sucked by the compressor  10  again. 
       FIG. 12  is a view showing the relationship between the evaporating temperature and COP (Coefficient of Performance: energy consumption efficiency).  FIG. 12  shows the proportional relation between the evaporating temperature and the COP. For example, when the evaporating temperature is 11[° C.], the COP is approximately 3.1 (shown by (A)). When the evaporating temperature is increased to 20[° C.], the COP increases up to approximately 3.9 (shown by (B)). The increase in the evaporating temperature may improve the COP accordingly. 
     In the refrigeration cycle apparatus  100  according to the present embodiment, the latent heat of the water contained in the air and the sensible heat may be processed by the heat exchanger  41  for dehumidification/humidification and the evaporator  70  respectively, so that the division of roles is achieved. Unlike the case where the evaporator  70  processes the latent heat and the sensible heat, the evaporating temperature of the refrigerant can be set higher. Thus, the air conditioning system can prevent deposition of the frost and needs no defrosting operation even when conventionally the evaporating temperature has to set to be the value lower than the dew point in the evaporator  70  and the frost deposited. 
     The use of the condensed exhaust heat in the condenser  20  may desorb the water adsorbed in the heat exchanger  41  for dehumidification/humidification (fin  45 ). The desorbed water may be disposed, or used for humidification. The heating device such as the heater for desorbing the water is no longer necessary, thus requiring no power for the heating device. This makes it possible to largely reduce the power consumption. 
     When the refrigeration cycle apparatus  100  according to the present embodiment is applied to the refrigerated warehouse under the conditions where external air is maintained at the dry-bulb temperature of 30[° C.], the relative humidity of 60[%], and absolute humidity of 16.04[g/kg], the control unit  80  may control each apparatus so that the refrigeration cycle apparatus is operated for the refrigerated room (air-conditioned space) in the refrigerated warehouse to be maintained and continued under the conditions of the dry-bulb temperature 10[° C.], the relative humidity 60[%], and the absolute humidity 4.56[g/kg]. 
     In the refrigeration cycle apparatus according to Embodiment 4, by making the water adsorbed by the fin  45  using the heat exchanger  41  for dehumidification/humidification as described in Embodiments 1 to 3 as the dehumidifying/humidifying device, the evaporating temperature of the refrigerant in the heat exchange with the air in the evaporator  70  does not have to be set in consideration of the latent heat caused by the water, so that the refrigerant may be controlled to the temperature in consideration of the sensible heat. This makes it possible to make the compression ratio in the compressor of the refrigeration cycle apparatus small, thus improving the energy performance represented by the COP in the refrigeration cycle apparatus as an index. 
     Embodiment 5 
       FIG. 13  shows an exemplary structure of the refrigeration cycle apparatus  100   a  according to Embodiment 3 of the present invention. The refrigeration cycle apparatus  100   a  of the present embodiment is formed, but is not limited to, as an air conditioning system for heating/cooling operations. The apparatuses shown in  FIG. 13  with the same reference numerals as those described in Embodiment 4 perform the same functions, so that explanations will be omitted. 
     The refrigeration cycle apparatus  100   a  is formed by the compressor  10 , the condenser  20 , the first on-off valve  30  and the second on-off valve  31  which are provided in parallel, the heat exchangers  41   a  and  41   b  for dehumidification/humidification which are provided in parallel, back-flow prevention members  50  and  51  which are provided in parallel, the throttle device  62 , and the evaporator  70 , being sequentially connected with the refrigerant pipe  1 . As described in Embodiments 1 to 3, the refrigeration cycle apparatus  100   a  includes heat exchangers  41   a  (a first heat exchanger) and  41   b  (a second heat exchanger) for dehumidification/humidification that are the heat exchangers  40  having the fin  45  with fine pores formed on the surface. These two heat exchangers  41   a  and  41   b  for dehumidification/humidification are independently built into the indoor unit independently. 
     The refrigerant pipe  1  is branched into refrigerant pipes  1   a  and  1   b . After the on-off valve  30 , the heat exchanger  41   a  for dehumidification/humidification, and the back-flow prevention member  50  are connected by refrigerant pipe  1   a , and the on-off valve  31 , the heat exchanger  41   b  for dehumidification/humidification and the back-flow prevention member  51  being connected by refrigerant pipe  1   b  respectively, these are joined together again. The refrigerant flowing in the refrigerant pipe  1  may employ the one described in Embodiment 2. The refrigeration cycle apparatus  100   a  is provided with a temperature/humidity detection unit  81  (a first temperature/humidity detection unit) at the inlet of the air passage of the evaporator  70  for detecting the temperature and humidity of air flowing into the evaporator  70 . 
     The temperature/humidity detection unit  81  may be of any type so far as the temperature and the humidity are detected and types are not limited in particular. For example, the temperature sensor such as the thermistor, thermometer, humidity sensor, and hygrometer may be employed. 
     The on-off valves  30  and  31  function as flow passage selecting units for selecting the refrigerant circuit that are not limited to the particular type. The back-flow prevention members  50  and  51  prevent back-flow of the refrigerant flowing through the refrigerant pipes  1   a  and  1   b . Such as a check valve may be employed, but is not limited to the particular type. The throttle device  62  is generally composed of a decompression valve and expansion valve for decompressing the refrigerant to expand. The electronic expansion valve may be employed, for example. The control unit  80  according to the present embodiment controls the respective apparatuses including the on-off valves  30 ,  31  in addition to the controlling operations described above. The control unit further performs the air passage control by switching the air passage switching units  301   a  to  304   a , and  301   b  to  304   b  described later, and calculates the relative humidity of the air in the evaporator  70  based on the information from the temperature/humidity detection unit  81  to convert the relative humidity into the dew point (dew-point temperature). 
       FIG. 14  shows a structure of an indoor unit  300  where the evaporator  70  and the like are built-in. The indoor unit  300  shown in  FIG. 14  is partially disposed in the refrigerated warehouse (air-conditioned space)  400  and the rest portion is disposed at the external air side  500 . In the indoor unit  300 , the heat exchangers  41   a  and  41   b  for dehumidification/humidification and the evaporator  70  as shown in  FIG. 13  are built-in. Blowers  90  and  91  such as a centrifugal fan and axial flow fan are disposed adjacent to the heat exchangers  41   a  and  41   b  for dehumidification/humidification. The indoor unit  300  is provided with a duct  310  which not only feeds air from the evaporator  70  to the refrigerated warehouse  400  but also sucks the air. 
     The indoor unit  300  is structured to disconnect the air passage (air flow) between the heat exchangers  41   a  and  41   b  for dehumidification/humidification. The indoor unit  300  is capable of switching the air passage. By switching the air passage the heat exchangers  41   a  and  41   b  for dehumidification/humidification can be communicated with the inside of the refrigerated warehouse  400  and the external air  500 . The operation for switching the air passage is performed by the air passage switching units  301   a  and  301   b ,  302   a  and  302   b ,  303   a  and  303   b , and  304   a  and  304   b , respectively. The air passage may be finely adjusted by the air passage adjustment units  305   a  and  305   b.    
     The air flow in the indoor unit  300  will be described. Referring to  FIG. 14 , the air passage switching units  301   a ,  302   b ,  303   b , and  304   a  are opened, and the air passage switching units  301   b ,  302   a ,  303   a , and  304   b  are closed. When the respective air passage switching units are in the aforementioned state, the built-in space of the heat exchanger  41   a  for dehumidification/humidification is communicated with the external air  500  to allow the air to flow from outside (arrow A). The built-in space of the heat exchanger  41   b  for dehumidification/humidification is communicated with the inside of the refrigerated warehouse  400  via the duct  310  to allow the air (for example, the temperature 10[° C.] and relative humidity 60[%])(arrow B) to flow in. 
     In the above structured air passages, the heat exchanger  41   a  for dehumidification/humidification performs desorption, and the heat exchanger  41   b  for dehumidification/humidification performs adsorption. Thereby, the latent heat may be processed by the heat exchanger  41   b  for dehumidification/humidification and the sensible heat may be processed by the evaporator  70  individually. Meanwhile, when the open/closed states of each air passage switching unit are inverted, the air flows into the built-in space of the heat exchanger  41   a  for dehumidification/humidification, and the expanded air flows into the built-in space of the heat exchanger  41   b  for dehumidification/humidification. The heat exchanger  41   a  for dehumidification/humidification performs adsorption, and the heat exchanger  41   b  for dehumidification/humidification performs desorption, respectively. 
       FIG. 15  is an explanatory view showing the state where the air passages in the indoor unit  300  is switched. Referring to  FIG. 15(   a ), the air passage switching units  301   a ,  302   b ,  303   b  and  304   a  are closed, and the air passage switching units  301   b ,  302   a ,  303   a  and  304   b  are opened. 
     As shown in  FIG. 15(   a ), the built-in space of the heat exchanger  41   b  for dehumidification/humidification is communicated with the external air  500  to allow the external air to flow in (arrow C). The built-in space of the heat exchanger  41   a  for dehumidification/humidification is communicated with the inside of the refrigerated warehouse  400  via the duct  310  to allow the air to flow in (arrow D). At this time, the heat exchanger  41   b  for dehumidification/humidification desorbs the water, and the heat exchanger  41   a  for dehumidification/humidification adsorbs the water.  FIG. 15(   b ) shows the same as what is shown in  FIG. 14 , so that the explanation will be omitted. 
       FIG. 16  is a P-h diagram (Mollier diagram) which represents the refrigerant state in the refrigeration cycle. The refrigerant state in the refrigeration cycle will be described based on  FIG. 16 . The vertical axis of the diagram denotes an absolute pressure (P), and the horizontal axis denotes enthalpy (h). Referring to  FIG. 16 , the region surrounded by the saturated liquid line and the saturated vapor line represents the refrigerant in the gas-liquid two-phase state. The region to the left of the saturated liquid line represents the liquefied refrigerant, and the region to the right of the saturated vapor line represents the gaseous refrigerant. That is, in the states ( 1 ) and ( 5 ), the refrigerant is gaseous, and in the states ( 2 ) and ( 4 ), the refrigerant is in the gas-liquid two-phase state. In the state ( 3 ), the refrigerant is liquefied. 
     The operation of the refrigeration cycle apparatus  100   a  will be described based on  FIGS. 13 and 16 . Descriptions will be given to when the on-off valve  30  is opened, the on-off valve  31  is closed, the heat exchanger  41   a  for dehumidification/humidification is operated for desorbing the water, and the heat exchanger  41   b  for dehumidification/humidification is operated for adsorbing the water. Since the on-off valve  31  is closed, the refrigerant does not flow into the heat exchanger  41   b  for dehumidification/humidification. 
     The refrigerant in the gaseous state of high temperature/pressure state compressed by the compressor  10  (in the state ( 1 ) shown in  FIG. 16 ) flows into the condenser  20 . The refrigerant in the aforementioned state turns into the gas-liquid two-phase state while partially releasing heat to the external air in the condenser  20  (the state ( 2 ) shown in  FIG. 16 ). The gas-liquid two-phase refrigerant of high pressure state flows into the heat exchanger  41   a  for dehumidification/humidification, and passes through the heat transfer pipe  46 . At this time, a heat exchange between the refrigerant and the air is conducted to increase temperature of the fin  45  and the ambient air to reduce the relative humidity. As a result, the water adsorbed on the fin  45  is desorbed. The gas-liquid two-phase refrigerant turns into the liquefied refrigerant (the state ( 3 ) shown in  FIG. 16 ). 
     The refrigerant flows in the back-flow prevention member  50  to be decompressed in the throttle device  62 . The decompressed refrigerant becomes a low pressure gas-liquid two-phase refrigerant (the state ( 4 ) shown in  FIG. 16 ). The gas-liquid two-phase refrigerant flows into the evaporator  70  and is evaporated by removing heat from the air to become a low pressure gaseous refrigerant (the state ( 5 ) shown in  FIG. 16 ). The air here adsorbs the water by the heat exchanger  41   b  for dehumidification/humidification as described later. The air is cooled to flow out into the refrigerated warehouse  400 . Then, the gaseous refrigerant is sucked by the compressor  10  again to circulate in the refrigerant circuit. The cooling/refrigerating operations are conducted by circulating the refrigerant in the refrigerant circuit while changing the states of the refrigerant by repeating the heat absorbing/releasing operations. 
       FIG. 17  is a psychrometric diagram for explaining the operation of the heat exchanger  41   b  for dehumidification/humidification in the refrigeration cycle apparatus  100   a . The operation of the above refrigeration cycle apparatus  100   a  will be described using the psychrometric diagram and the structural view of  FIG. 14 . In  FIGS. 14 and 17 , for the air passing through the heat exchanger  41   b  for dehumidification/humidification made to be communicated with the inside of the refrigerated warehouse  400 , descriptions are given to the state ( 1 ) shown in  FIG. 17  representing the state of the air before passing through the heat exchanger  41   b  for dehumidification/humidification, the state ( 2 ) shown in  FIG. 17  representing the state of the air immediately after passing through the heat exchanger  41   b  for dehumidification/humidification, and the state ( 3 ) shown in  FIG. 17  representing the state of the air immediately after the heat exchange with the evaporator  70 . 
     Descriptions will be given to when the heat exchanger  41   b  for dehumidification/humidification adsorbs the water content of the air inside the refrigerated warehouse  400 . The air in the state ( 1 ) is the dry-bulb temperature 10[° C.], the relative humidity 60[%], and the absolute humidity 4.56[g/kg]. When the air in the aforementioned state flows into the heat exchanger  41   b  for dehumidification/humidification, the air is brought into the state ( 2 ) along an equi-enthalpy line to be fed to the evaporator  70 , where the relative humidity being reduced from 60[%] to 30[%], the absolute humidity being reduced from 4.56[g/kg] to 2.96[g/kg], and the dry-bulb temperature being increased from 10[° C.] to 14[° C.]. 
     Since the amount of the water adsorbed by the heat exchanger  41   b  for dehumidification/humidification becomes large in the region where the relative humidity is equal to or higher than approximately 30%, it is possible to dehumidify the air in the state ( 1 ). The air in the state ( 2 ) is cooled by the removal of the sensible heat through the heat exchange of the evaporator  70  in the state of constant absolute humidity to turn into the air of the state ( 3 ) where the relative humidity is lower than 100[%] and the dry-bulb temperature is −2[° C.]. 
     In most cases, the inside of the refrigerated warehouse  400  is generally kept at the temperature range lower than 10[° C.], and the evaporating temperature is required to set lower than 0[° C.]. However, the refrigeration cycle apparatus  100   a  is capable of setting the evaporating temperature of the evaporator  70  (14[° C.] of the state ( 2 )) to be higher than the dew-point temperature (for example, the dew-point temperature −2.9[° C.] of the state ( 2 )) so as not to allow the refrigeration cycle to execute a defrosting operation for removing the frost formed on the evaporator  70 . 
     The control unit  80  may be configured to adjust the evaporating temperature of the evaporator  70  to increase by controlling the opening of the throttle device  62 , the drive frequency of the compressor  10 , the rotating speed of the blower  91  and the like. As described in  FIG. 12 , if the evaporating temperature is set high, the COP may be improved by that amount. Since the evaporating temperature of the evaporator  70  may be higher than the dew point, no drain occurs. That is, no drain pipe is required, thus reducing the manufacturing cost. 
     The control unit  80  calculates the relative humidity of the air in the evaporator  70  based on the information from the temperature/humidity detection unit  81 . The calculated relative humidity is then converted into the dew point. The dew point may be detected based on the converted result. Air in the state ( 3 ) is diffused into the refrigerated warehouse  400  to maintain the dry-bulb temperature at 10[° C.] or lower. The amount of the water content which can be adsorbed by the heat exchanger  41   b  for dehumidification/humidification is limited. When it is determined that the relative humidity of the heat exchanger  41   g  for dehumidification/humidification at the outlet of the air passage becomes equal to or larger than a predetermined threshold value based on the detection information from the temperature/humidity detection unit  81 , the control unit  80  switches the on-off valve  30  from the open to the closed state, and the on-off valve  31  from the closed to the open state to switch the refrigerant flow. The gaseous refrigerant of high temperature/pressure is made to flow into the heat exchanger  41   b  for dehumidification/humidification to increase temperatures of the fin  45  and the ambient air. 
     That is, the operation of the heat exchanger  41   b  for dehumidification/humidification which has been adsorbing the water is switched to desorb the water. When temperatures of the fin  45  of the heat exchanger  41   b  for dehumidification/humidification and the ambient air are increased, the relative humidity is decreased to release the adsorbed water for reproduction. Meanwhile, the refrigerant flow passage is switched, so that the heat exchanger  41   a  for dehumidification/humidification comes to adsorb the water in the air. The heat exchanger  41   a  for dehumidification/humidification is structured to adsorb the water in the air such that the air inside the warehouse  400  is dehumidified from the state ( 1 ) to ( 2 ) as shown in  FIG. 17 . 
     The amount of the water which can be adsorbed by the heat exchanger  41   a  for dehumidification/humidification is limited. When it is determined that the relative humidity of the heat exchanger  41   a  for dehumidification/humidification at the outlet side of the air passage becomes equal to or higher than a predetermined threshold value based on the detection information from the temperature/humidity detection unit  81 , the control unit  80  switches the on-off valve  30  from the closed to the open state, and the on-off valve  31  from the open to the closed state to switch the refrigerant flow. The gaseous refrigerant of high temperature/pressure is fed into the heat exchanger  41   a  for dehumidification/humidification to increase temperatures of the fin  45  and the ambient air such that the relative humidity is lowered to desorb the water. 
     As mentioned above, when one of the heat exchangers for dehumidification/humidification (heat exchanger  41   b  for dehumidification/humidification) adsorbs the water, the refrigeration cycle apparatus  100   a  is structured to allow the other heat exchanger for dehumidification/humidification (heat exchanger  41   a  for dehumidification/humidification) to desorb the water. The operations of the heat exchangers are alternately switched depending on the amount of the adsorbed water. Switching of the air passage to select the refrigerant flow passage allows the humidity (latent heat) of the air in the refrigerated warehouse  400  to be removed continuously. 
     Table 2 collectively shows control states of the on-off valves  30  and  31  (flow passage switching unit) and air passage switching units  301   a  to  304   b , and functions of the heat exchangers  41   a  and  41   b  for dehumidification/humidification. In Table 2, pattern 1 represents that the heat exchanger  41   a  for dehumidification/humidification adsorbs water, and the heat exchanger  41   b  for dehumidification/humidification desorbs the adsorbed water as shown in  FIG. 15(   a ). Pattern 2 represents that the heat exchanger  41   a  for dehumidification/humidification desorbs the adsorbed water, and the heat exchanger  41   b  for dehumidification/humidification adsorbs the water as shown in  FIG. 15(   b ). The continuous operation may be performed by switching the patterns 1 and 2. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
             
            
               
                   
                   
               
               
                   
                   
                   
                 Air 
                 Air 
                 Air 
                 Air 
               
               
                   
                   
                   
                 passage 
                 passage 
                 passage 
                 passage 
               
               
                   
                 Heat 
                 On-off 
                 switching 
                 switching 
                 switching 
                 switching 
               
               
                   
                 exchanger 
                 valve 
                 unit 
                 unit 
                 unit 
                 unit 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Pattern 
                 41a 
                 41b 
                 30 
                 31 
                 301a 
                 301b 
                 302a 
                 302b 
                 303a 
                 303b 
                 304a 
                 304b 
               
               
                   
               
               
                 1 
                 Adsorb 
                 Desorb 
                 Close 
                 Open 
                 Close 
                 Open 
                 Open 
                 Close 
                 Open 
                 Close 
                 Close 
                 Open 
               
               
                 2 
                 Desorb 
                 Adsorb 
                 Open 
                 Close 
                 Open 
                 Close 
                 Close 
                 Open 
                 Close 
                 Open 
                 Open 
                 Close 
               
               
                   
               
            
           
         
       
     
     As described above, the refrigeration cycle apparatus  100   a  according to Embodiment 5 is structured to allow the heat exchangers  41   a  and  41   b  for dehumidification/humidification composed of the heat exchanger  40  according to Embodiments 1 to 3 to alternately adsorb the water in air in the refrigerated warehouse  400  continuously. This makes it possible to eliminate the defrosting operation conventionally frequently performed to further reduce the power consumption for the defrosting operation. The evaporating temperature of the evaporator  70  may be set higher than the dew-point temperature to enable an efficient operation of the refrigeration cycle. 
     Since the water adsorbed by the heat exchangers  41   a  and  41   b  for dehumidification/humidification is configured to be desorbed using the heat (exhaust heat which is not required for cooling the inside of the refrigerated warehouse  400 ) of the refrigerant condensed by the condenser  20 , no specific heating device for the desorption is required, and the space for accommodation can be saved, so that no electric power is required for heating by the heating unit. 
     The refrigeration cycle apparatus  100   a  does not require a high pressure in excess of a critical pressure. That is, the compressor  10 , the condenser  20  and the refrigerant pipe  1  (including refrigerant pipes  1   a  and  1   b ) connecting those may be low in pressure-resistant performance, so that manufacturing costs can be reduced. The compression ratio of the refrigerant in the compressor  10  may be suppressed, thus improving the operation efficiency of the compressor  10 . That is, COP can be significantly improved and energy saving can be achieved. 
     Embodiment 6 
       FIG. 18  shows an exemplary structure of a refrigeration cycle apparatus  100   b  according to Embodiment 6 of the present invention. Descriptions will be given, but not limited in particular, to that the refrigeration cycle apparatus  100   b  of the present embodiment is, for example, an air conditioning system for cooling/heating operations. In  FIG. 18 , since the apparatuses designated with the same reference numerals as those described in Embodiments 4 and 5 perform the same functions, explanations will be omitted. 
     The refrigeration cycle apparatus  100   b  is formed by the compressor  10 , the condenser  20 , the first and the second on-off valves  32  and  33  provided in parallel, the heat exchangers  41   c  and  41   d  for dehumidification/humidification provided in parallel, the on-off valves  34  and  35  provided in parallel, the throttle device  85  (third throttle device), and the evaporator  70 , being sequentially connecting with the refrigerant pipe  1 . The refrigeration cycle apparatus  100   b  is also provided with the heat exchangers  41   c  (a first heat exchanger) and  41   d  (a second heat exchanger) for dehumidification/humidification that are the heat exchanger  40  having the fin  45  with the fine pores formed on the surface. Those two heat exchangers  41   c  and  41   d  for dehumidification/humidification are built into the indoor unit separately. 
     The refrigerant pipe  1  is branched into the refrigerant pipes  1   c  and  1   d . After the on-off valve  32 , the heat exchanger  41   c  for dehumidification/humidification, and the on-off valve  34  are connected by the refrigerant pipe  1   c , and the on-off valve  33 , the heat exchanger  41   d  for dehumidification/humidification, and the on-off valve  35  are connected by the refrigerant pipe  1   d , these are then joined again. The refrigerant flowing in the refrigerant pipe  1  may employ the refrigerant described above. The refrigerant pipes  1   c  and  1   d  include a bypass pipe  2  (a first bypass pipe) branched from the refrigerant pipe  1   c  between the on-off valve  32  and the heat exchanger  41   c  for dehumidification/humidification to join with the refrigerant pipe  1   d  between the heat exchanger  41   d  for dehumidification/humidification and the on-off valve  35 , and a bypass pipe  3  (a second bypass pipe) branched from the refrigerant pipe  1   d  between the on-off valve  33  and the heat exchanger  41   d  for dehumidification/humidification to join with the refrigerant pipe  1   c  between the heat exchanger  41   c  for dehumidification/humidification and the on-off valve  34 . 
     The bypass pipe  3  includes a throttle device  63  (a first throttle device) and an on-off valve  36  (a third on-off valve). The bypass pipe  2  includes a throttle device  64  (a second throttle device) and an on-off valve  37  (a fourth on-off valve). The refrigeration cycle apparatus  100   b  includes a temperature/humidity detection unit  81  for detecting the temperature/humidity of the evaporator  70  at the inlet side of the air passage thereof, and a temperature/humidity detection unit  82  (a second temperature/humidity detection unit) for detecting the temperature/humidity of the heat exchangers  41   c  and  41   d  for dehumidification/humidification at the outlet side of the air passage of the heat exchanger  41   c  for dehumidification/humidification, respectively. 
     The temperature/humidity detection units  81  and  82  may be of any type so far as the temperature and the humidity are detected and types are not limited in particular. For example, the temperature sensor such as the thermistor, thermometer, humidity sensor, and hygrometer may be employed. In the example, the apparatus employs a single unit of the temperature/humidity detection units  81  and  82 , respectively, however, plural units may be employed without being limited to the above. The temperature/humidity detection unit  82  may be disposed at the outlet sides of the respective air passages of the heat exchangers  41   c  and  41   d  for dehumidification/humidification. 
     The refrigeration cycle apparatus  100   b  is provided with a control unit  80   a  which controls a drive frequency of the compressor  10 , opening of the on-off valves  32  to  37 , and opening of the throttle devices  63 ,  64  and  85 . The on-off valves  32  to  37  are operated for switching the flow passages, not limited to a specific type. The throttle devices  63 ,  64  and  85  are generally composed of the decompression and expansion valves to decompress and expand the refrigerant, and may be composed of an electronic expansion valve and the like. 
     In addition to controlling each apparatus, the control unit  80   a  calculates the relative humidity of the heat exchanger  41   c  for dehumidification/humidification at the outlet side of the air passage based on the signal which contains data from the temperature/humidity detection unit  82  to convert the calculated relative humidity into the dew point (dew-point temperature). The control unit  80  also controls the relative humidity in the evaporator  70  based on the information from the temperature/humidity detection unit  81  to convert and the calculated relative humidity into the dew point (dew-point temperature). When the desorption/adsorption function is switched between the heat exchangers  41   c  and  41   d  for dehumidification/humidification, the control unit  80   a  calculates the relative humidity of the heat exchanger  41   d  for dehumidification/humidification at the outlet side of the air passage to convert the calculated relative humidity into the dew point (dew-point temperature). 
       FIG. 19  shows a structure of an indoor unit  300   a  where the evaporator  70  and the like are built-in. The basic structure of the indoor unit  300   a  will be described based on  FIG. 19 . Descriptions will be given to differences from the indoor unit  300  shown in  FIG. 14 . In  FIG. 19 , a part of the indoor unit  300   a  is disposed inside (air-conditioned space)  401  of the room, and the rest is disposed at the side of the external air  500 . In the indoor unit  300   a , the heat exchangers  41   c  and  41   d  for dehumidification/humidification and the evaporator  70  shown in  FIG. 18  are built-in. 
     The indoor unit  300   a  is structured to disconnect the air passage between the heat exchangers  41   c  and  41   d  for dehumidification/humidification. The indoor unit  300   a  is allowed to switch the air passage to communicate the heat exchangers  41   c  and  41   d  for dehumidification/humidification with the interior  401  and the external air  500 . The switching of the air passage may be performed by air passage switching units  311   a  and  311   b ,  312   a  and  312   b ,  313   a  and  313   b , and  314   a  and  314   b , respectively. The fine adjustment of the air passage may be performed by the air passage adjustment units  315   a  and  315   b.    
     The air flow in the indoor unit  300   a  will be described.  FIG. 19  shows that the air passage switching units  311   a ,  312   b ,  313   b  and  314   a  are opened, and the air passage switching units  311   b ,  312   a ,  313   a  and  314   b  are closed. In the aforementioned state of the air passage switching units, the built-in space of the heat exchanger  41   c  for dehumidification/humidification is communicated with the external air  500  to allow the air to flow from outside (arrow A). The built-in space of the heat exchanger  41   d  for dehumidification/humidification is communicated with the interior  401  via the duct  310  to allow the air (for example, temperature 26[° C.] and relative humidity 60[%]) to flow in (arrow B). 
     When the air passages are formed as described above, the heat exchanger  41   c  for dehumidification/humidification performs the desorption, and the heat exchanger  41   d  for dehumidification/humidification performs the adsorption. Thereby, the heat exchanger  41   d  for dehumidification/humidification processes latent heat, and the evaporator  70  processes sensible heat separately. Meanwhile, when the open-close states of the respective air passage switching units are inverted, the heat exchanger  41   c  for dehumidification/humidification performs adsorption, and the heat exchanger  41   d  for humidification/humidification performs desorption. 
       FIG. 20  is an explanatory view showing the state where the air passage of the indoor unit  300   a  is switched. Referring to  FIG. 20 , a portion of the indoor unit  300   a  is disposed in the interior  401 , and the rest is disposed at the side of the external air  500 .  FIG. 20(   a ) shows that the air passage switching units  311   a ,  312   b ,  313   b  and  314   a  are closed, and the air passage switching units  311   b ,  312   a ,  313   a  and  314   b  are closed. 
     Referring to  FIG. 20(   a ), the built-in space of the heat exchanger  41   d  for dehumidification/humidification is communicated with the external air  500  to allow the external air to flow in (arrow C). The built-in space of the heat exchanger  41   c  for dehumidification/humidification is communicated with the interior  401  via the duct  310  to allow the air to flow in (arrow D). At this time, the heat exchanger  41   d  for dehumidification/humidification desorbs water, and the heat exchanger  41   c  for dehumidification/humidification adsorbs the water, respectively.  FIG. 20(   b ) shows the same as what is shown in  FIG. 19 , so that the explanation will be omitted. 
     In the case where the refrigeration cycle apparatus  100   b  is applied to an air-conditioning apparatus such as the room air-conditioner and all-in-one air conditioning system with the condition of the external air  500  being kept at the dry-bulb temperature 30[° C.], the relative humidity 60[%], and the absolute humidity 16.04[g/kg], the control unit  80   a  should control the respective apparatuses to operate the refrigeration cycle apparatus  100   b  while maintaining and continuing the interior  401  (air-conditioned space) under conditions of the dry-bulb temperature 26[° C.], the relative humidity 60[%], and the absolute humidity 8.74[g/kg]. 
       FIG. 21  is a P-h diagram (Mollier diagram) which represents the refrigerant state in the refrigeration cycle. The refrigerant state in the refrigeration cycle will be described based on  FIG. 21 . Referring to  FIG. 21 , it is configured to be able to understand that the refrigerant is gaseous in the states ( 1 ) and ( 7 ). The refrigerant is in the gas-liquid two-phase state in the states ( 2 ), ( 4 ), ( 5 ) and ( 6 ). The refrigerant is liquefied in the state ( 3 ). 
     The operation of the refrigeration cycle apparatus  100   b  will be described based on  FIGS. 18 and 21 . Descriptions will be given on the operation of the refrigeration cycle apparatus  100   b  when the on-off vales  32 ,  34  and  35  are opened, the on-off valves  33 ,  37  and  36  are closed, the heat exchanger  41   c  for dehumidification/humidification is operated as the heat exchanger for desorption, and the heat exchanger  41   d  for dehumidification/humidification is operated as the heat exchanger for adsorption. 
     The gaseous refrigerant of high temperature/pressure compressed by the compressor  10  (the state ( 1 ) shown in  FIG. 21 ) flows into the condenser  20 . The refrigerant in the aforementioned state turns into the gas-liquid two-phase state (state ( 2 ) shown in  FIG. 21 ) while partially releasing the heat to the external air by the condenser  20 . The high pressure gas-liquid two-phase refrigerant flows into the heat exchanger  41   c  for dehumidification/humidification. The gas-liquid two-phase refrigerant flowing into the heat exchanger  41   c  for dehumidification/humidification increases the temperatures of the fin  45  and the ambient air to reduce the relative humidity. Thereby, the water adsorbed in the fin  45  is desorbed. The gas-liquid two-phase refrigerant turns into the liquefied refrigerant (state ( 3 ) shown in  FIG. 21 ). 
     The aforementioned refrigerant flows through the on-off valve  36  to be decompressed by the throttle device  63 . The decompressed refrigerant turns into the low pressure gas-liquid two-phase state (state ( 4 ) shown in  FIG. 21 , here, the first evaporating temperature). Then the gas-liquid two-phase refrigerant flows into the heat exchanger  41   d  for dehumidification/humidification to lower the temperatures of the fin  45  and the ambient air with the first evaporating temperature lower than the air and enhance the adsorbing performance. The gas-liquid two-phase refrigerant flowing into the heat exchanger  41   d  for dehumidification/humidification partially evaporates to turn into the low pressure gas-liquid two-phase refrigerant (state ( 5 ) shown in  FIG. 21 ). The gas-liquid two-phase refrigerant is further decompressed by the throttle device  85  to be a second evaporating temperature (state ( 6 ) shown in  FIG. 21 ), then flows into the evaporator  70  to turn into a low pressure gaseous refrigerant by absorbing the sensible heat of the air through the heat exchange (state ( 7 ) shown in  FIG. 21 ). The gaseous refrigerant is sucked by the compressor  10  again to circulate in the refrigerant circuit. 
     The refrigeration cycle apparatus  100   b  is structured to allow the refrigerant which has passed through one of the heat exchangers for dehumidification/humidification (heat exchanger  41   c  for dehumidification/humidification) to flow into the other heat exchanger for dehumidification/humidification (heat exchanger  41   d  for dehumidification/humidification) via a bypass pipe (bypass pipe  3 ). As a result, the heat exchanger  41  for dehumidification/humidification efficiently desorbs the water using the heat of the refrigerant related to condensation, and the other heat exchanger  41  for dehumidification/humidification efficiently adsorbs the water using the heat of the refrigerant related to evaporation to enhance adsorption/desorption performance and improve the performance of the refrigeration cycle apparatus. 
       FIG. 22  is a psychrometric diagram for explaining the operation of the heat exchanger  41   d  for dehumidification/humidification of the refrigeration cycle apparatus  100   b . The operation of the above-mentioned refrigeration cycle apparatus  100   b  will be described referring to the psychrometric diagram and the structure shown in  FIG. 19 . Referring to  FIGS. 19 and 22 , for the air passing through the heat exchanger  41   d  for dehumidification/humidification communicating with the interior  401 , the state ( 1 ) shown in  FIG. 22  represents the state of air before passing through the heat exchanger  41   d  for dehumidification/humidification, the point ( 2 ) shown in  FIG. 22  represents the state of air immediately after passing through the heat exchanger  41   d  for dehumidification/humidification, and the point ( 3 ) shown in  FIG. 22  represents the state of air immediately after the heat exchange with the evaporator  70 . 
     The operation of the heat exchanger  41   d  for dehumidification/humidification when adsorbing the water of air in the interior  401  will be described. The air in the state ( 1 ) is the dry-bulb temperature of 26[° C.] and the relative humidity 60[%] when the air in this state flows into the heat exchanger  41   d  for dehumidification/humidification, the air is subjected to isothermal or cooling adsorption in the heat exchanger  41   d  to turn into the state ( 2 ) to flow into the evaporator  70 . Same the amount of water which can be adsorbed by the heat exchanger  41   b  for dehumidification/humidification is increased in the region of the relative humidity of 30% or higher, the air in the state ( 1 ) can be dehumidified. 
     The air in the state ( 2 ) is subjected to heat exchange by the evaporator  70  to turn into the air in the state ( 3 ). The air in the state ( 2 ) is cooled with only the sensible heat being removed at a constant absolute humidity by the evaporator  70  to turn into the state ( 3 ) where the relative humidity is lower than 100[%] and the dry-bulb temperature is 14[° C.]. The air in the state ( 3 ) is supplied to the interior  401 . 
     The control unit  80   a  controls the opening of the throttle devices  63  and  85 , the drive frequency of the compressor  10 , and the rotating speed of the blower  91 , and adjusts the first evaporating temperature to be equal to or higher than the dew point (in the present embodiment, 18[° C.]) of the intake air in the heat exchanger  41   d  for dehumidification/humidification. The control unit controls the second evaporating temperature to be equal to or higher than the dew point (in the present embodiment, 14[° C.]) of air at the outlet of the heat exchanger  41   d  for dehumidification/humidification. The control unit  80   a  converts the data of temperature and humidity detected by the temperature/humidity detection units  81  and  82  into the dew point.  FIG. 22  shows the first evaporating temperature of 18[° C.], and the second evaporating temperature of 14[° C.]. 
     The amount of water is limited which can be adsorbed by the heat exchanger  41   d  for dehumidification/humidification functioning as a heat adsorption exchanger. When it is determined that the relative humidity in the evaporator  70  becomes equal to or higher than a predetermined threshold value based on the data detected by the temperature/humidity detection unit  81 , the control unit  80   a  switches on-off valves  32 ,  36  and  35  from the open to the closed state, and on-off valves  33 ,  37  and  34  from the closed to the open state to change the refrigerant flow. A high temperature/pressure gaseous refrigerant is fed into the heat exchanger  41   d  for dehumidification/humidification to increase the temperatures of the fin  45  and the ambient air for desorption and reproduction. 
     Since the refrigerant flow passage is switched, the heat exchanger  41   c  for dehumidification/humidification is operated as an adsorption heat exchanger. In the heat exchanger  41   c  for dehumidification/humidification, the water contained in the air is adsorbed. The refrigeration cycle apparatus  100   b , alternately switches heat exchangers according to the water adsorption amount such that when one of the heat exchangers for dehumidification/humidification (heat exchanger  41   d  for dehumidification/humidification) is adsorbs the water, the other heat exchanger for dehumidification/humidification (heat exchanger  41   c  for dehumidification/humidification) desorbs the water. The air in the interior  401  may be continuously dehumidified (latent heat may be removed) by switching the air passages. 
     The external air for example, the dry-bulb temperature 32[° C.] and the relative humidity 60[%], is supplied from the external air  500  side to the heat exchanger  41   c  for dehumidification/humidification by the blower  90 . The heat exchanger  41   c  for dehumidification/humidification desorbs the adsorbed water. Then, the absolute humidity is increased through the desorption, and the air is discharged to the external air  500  again. The air is merely discharged here, however, the desorbed water may be used for humidification. In this way, the latent heat may be removed by the heat exchangers  41   c ,  41   d  for dehumidification/humidification, and the sensible heat may be removed by the evaporator  70 . The exhaust heat generated by condensation in the condenser  20  may be used for desorbing the adsorbed water, air-conditioning and refrigerating performance is significantly improved. 
     Table 3 shows control states of the on-off valves  32  to  37  and functions of the heat exchangers  41   c ,  41   d  for dehumidification/humidification. Referring to Table 3, the pattern 1 shows that the heat exchanger  41   d  for dehumidification/humidification adsorbs the water, and the heat exchanger  41   c  for dehumidification/humidification desorbs the adsorbed water as shown in  FIG. 20(   b ). Then, the on-off valves  32 ,  36  and  35  are opened, and the on-off valves  33 ,  37  and  34  are closed. The pattern  2  shows that the heat exchanger  41   d  for dehumidification/humidification desorbs the adsorbed water, and the heat exchanger  41   c  for dehumidification/humidification adsorbs the water as shown in  FIG. 20(   a ). Then, the on-off valves  33 ,  37  and  34  are opened, and the on-off valves  32 ,  36  and  35  are closed. Continuous operations may be performed by alternately switching the patterns 1 and 2. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                   
                   
                 On-off 
                 On-off 
                 On-off 
               
               
                 Pat- 
                 Heat Exchanger 
                 valve 
                 valve 
                 valve 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 tern 
                 41c 
                 41d 
                 32 
                 33 
                 36 
                 37 
                 34 
                 35 
               
               
                   
               
               
                 1 
                 Desorp- 
                 Adsorption 
                 Open 
                 Close 
                 Open 
                 Close 
                 Close 
                 Open 
               
               
                   
                 tion 
               
               
                 2 
                 Adsorp- 
                 Desorption 
                 Close 
                 Open 
                 Close 
                 Open 
                 Open 
                 Close 
               
               
                   
                 tion 
               
               
                   
               
            
           
         
       
     
     When either of the heat exchangers  41   c  and  41   d  for dehumidification/humidification desorbs the water, the refrigerant is condensed therein. When adsorbing the water, the refrigerant is evaporated. Functions of the heat exchangers  41   c  and  41   d  for dehumidification/humidification may be switched by controlling opening of each on-off valve to switch the refrigerant flow and continuous operation is possible while switching adsorption and desorption alternately. 
     When the air-conditioned space is at the dry-bulb temperature of 26[° C.] and the relative humidity of 60[%], and the external air is at the dry-bulb temperature of 32[° C.] and the relative humidity of 60[%], the conventional refrigeration cycle apparatus is used to adjust the balance of the condenser  20  at the condensation temperature of about 47[° C.] and the evaporator  70  at the evaporating temperature of about 11[° C.] to process both the sensible heat (cooling operation) and the latent heat (dehumidifying operation) of the air-conditioned space simultaneously. Such a refrigeration cycle apparatus requires the evaporating temperature to be set low, so that the operation efficiency is poor. 
     The refrigeration cycle apparatus  100   b  allows the sensible heat processing (cooling operation) and the latent heat processing (dehumidifying operation) in the air-conditioned space to be conducted separately. The evaporator  70  is operated only for processing the sensible heat, so that the evaporating temperature can be set high. The evaporating temperature conventionally set at 11[° C.] may be increased to be as high as approximately 14[° C.]. As a result, the refrigerant cycle efficiency may be largely improved. 
     As shown in  FIG. 12 , the evaporating temperature is proportional to the COP. In Embodiment 4, when the evaporating temperature is 11[° C.], the COP is approximately 3.1 ((A) in the drawing). When the evaporating temperature is increased to 14[° C.], the COP is increased up to approximately 3.3 (shown as the point (B) in the drawing). The increase in the evaporating temperature by 3[° C.] may improve the COP by approximately 14%. 
     Likewise Embodiment 5, the refrigeration cycle apparatus  100   b  according to Embodiment 6 is not required to conduct defrosting, and allows the evaporating temperature of the evaporator  70  to be set high. In the present embodiment, since the refrigerant of the first evaporating temperature lower than the air is made to lower the temperature of the fins  45  of the heat exchanger  41   c  or  41   d  for dehumidification/humidification on the side of adsorbing the water and the ambient air to increase the relative humidity so as to promote the water adsorption, it is possible to realize a higher performance operation. 
     Example 7 
       FIG. 23  shows an exemplary structure of a refrigeration cycle apparatus  100   c  according to Embodiment 7 of the present invention. The refrigeration cycle apparatus  100   c  of the present embodiment is described as, for example, but not limited to, the air conditioning system for cooling/heating operations. Referring to  FIG. 23 , since what is designated with the same reference numerals as those described in Embodiments 4, 5 and 6 have the same functions, explanations will be omitted. 
     The refrigeration cycle apparatus  100   c  is formed by sequentially connecting the compressor  10 , the condenser  20 , the on-off valve  32  as the first on-off valve and the on-off valve  33  as the second on-off valve that are provided in parallel, the heat exchangers  41   e  and  41   f  for dehumidification/humidification provided in parallel, three-way valves  38  and  39  provided in parallel, the on-off valves  34  and  35  provided in parallel, throttle device  85 , and evaporator  70  with the refrigerant pipe  1 . Here, the refrigeration cycle apparatus  100   c  is also provided with the heat exchanger  41   e  (a first heat exchanger) for dehumidification/humidification and the heat exchanger  41   f  (a second heat exchanger) for dehumidification/humidification that are the heat exchanger  40  including the fin  45  which fine pores are formed on the surface. Those two heat exchangers  41   e  and  41   f  for dehumidification/humidification are built into the indoor unit separately. The control unit  80   b  controls the three-way valves  38  and  39  to switch the refrigerant flow passage. 
     Likewise the refrigeration cycle apparatus  100   b  according to the above Embodiment 6, the refrigerant pipe  1  is branched into the refrigerant pipes  1   c  and  1   d , and after connecting the on-off valve  32 , the heat exchanger  41   e  for dehumidification/humidification, and the three-way valve  38  with the refrigerant pipe  1   c  connecting the on-off valve  33 , the heat exchanger  41   f  for dehumidification/humidification, and the three-way valve  39  with the refrigerant pipe  1   b , respectively, they are joined again. The aforementioned refrigerant may be employed as the one flowing through the refrigerant pipe  1 . The refrigerant pipes  1   c  and  1   d  include a bypass pipe  2   a  (a first bypass pipe) which is branched from the refrigerant pipe  1   c  between the on-off valve  32  and the heat exchanger  41   e  for dehumidification/humidification to join with the refrigerant pipe  1   d  between the heat exchanger  41   f  for dehumidification/humidification and the three-way valve  39 , and a bypass pipe  3   a  (a second bypass pipe) which is branched from the refrigerant pipe  1   d  between the on-off valve  33  and the heat exchanger  41   f  for dehumidification/humidification to join with the refrigerant pipe  1   c  between the heat exchanger  41   e  for dehumidification/humidification and the three-way valve  38 . 
     The bypass pipe  3   a  is provided with the throttle device  63 . The bypass pipe  2   a  is provided with the throttle device  64 . The refrigeration cycle apparatus  100   c  is provided with a temperature/humidity detection unit (not shown) for detecting the temperature and humidity of the evaporator  70  at the inlet of the air passage of the evaporator  70 . The temperature/humidity detection unit is not limited to the specific type so far as the temperature and the humidity may be detected. For example, a temperature sensor such as a thermistor, thermometer, humidity sensor, and hygrometer may be employed. 
     The refrigeration cycle apparatus  100   c  is provided with a control unit (not shown) for controlling the drive frequency of the compressor  10 , opening of the on-off valves  32 ,  33 , opening of the throttle devices  63 ,  64  and  85 , and opening of the three-way valves  38 ,  39 . The three-way valves  38  and  39  switch the flow of the refrigerant flowing through the refrigerant pipes  1   a  and  1   b  to switch the functions (adsorption and desorption) of the heat exchangers  41   e  and  41   f  for dehumidification/humidification. 
     The operation of the refrigeration cycle apparatus  100   c  will be described based on  FIG. 23  on the assumption that the on-off valve  32  is opened, the on-off valve  33  is closed, the heat exchanger  41   e  for dehumidification/humidification is operated to desorb the water, and the heat exchanger  41   f  for dehumidification/humidification is operated to adsorb the water. 
     A high temperature/pressure gaseous refrigerant compressed by the compressor  10  flows into the condenser  20 . The refrigerant in the aforementioned state becomes the gas-liquid two-phase refrigerant in the condenser  20  while partially releasing the heat to the external air. The high pressure gas-liquid two-phase refrigerant flows into the heat exchanger  41   e  for dehumidification/humidification. The incoming gas-liquid two-phase refrigerant passes through the heat transfer pipe  46  to allow the heat exchange between the refrigerant and air and then increase the temperature of the fins  45  and the ambient air to lower the relative humidity. Thereby, the water adsorbed in the fin  45  is desorbed. The gas-liquid two-phase refrigerant is liquefied into the liquid refrigerant. 
     The refrigerant flowing from the heat exchanger  41   e  for dehumidification/humidification has a flow direction determined by the three-way valve  38  under the control of the control unit  80   b . If the refrigerant is controlled to flow through the bypass pipe  3   a , the low pressure gas-liquid two-phase refrigerant flows into the heat exchanger  41   f  for dehumidification/humidification to lower the temperatures of the fins  45  and the ambient air like the Embodiment 6. This makes it possible to enhance the adsorbing performance of the heat exchanger  41   f  for dehumidification/humidification. The gas-liquid two-phase refrigerant flowing out from the heat exchanger  41   f  for dehumidification/humidification is decompressed by the throttle device  85  via the three-way valve  38 , on-off valve  35 , and bypass pipe  1   d , flowing into the evaporator  70  to become the low pressure gaseous refrigerant while removing the sensible heat of the air by the heat exchange, then being sucked by the compressor  10  to be circulate in the refrigerant circuit. The operation of the refrigeration cycle apparatus  100   c  is reversed compared with that of the three-way valves  38  and  39  when closing the on-off valve  32 , opening the on-off valve  33 , making the heat exchanger  41   f  for dehumidification/humidification desorb the water, and making the heat exchanger  41   e  for dehumidification/humidification adsorb the water. 
     In Embodiment 7, the apparatus is provided with the three-way valves  38 ,  39  to facilitate water adsorption by lowering the temperatures of the fins  45  of the heat exchanger  41   e  or  41   f  for dehumidification/humidification on the side of the water adsorbtion and the ambient air to increase the relative humidity, so that it is possible to operate the apparatus with higher performance. 
     Embodiment 8 
     In Embodiments 4 to 7, the heat exchanger  40  according to Embodiments 1 to 3 is applied only to the heat exchanger  41  for dehumidification/humidification, however, it is not limited thereto. For example, the condenser  20  and the evaporator  70  which serve as the heat exchangers may be provided with the fin  45  for adsorbing the water. 
     In Embodiments 4 to 7 as described above, two heat exchangers  41   a ,  41   b  for dehumidification/humidification are used for alternate desorption and adsorption, however, the number of the heat exchangers  41  for dehumidification/humidification is not limited. 
     In Embodiments 4 to 7, the compressor  10  is not limited to a specific type. For example, the inverter compressor capable of controlling the capacity, and the constant rate compressor which performs the compression at a constant rate may be employed. In the respective embodiments, a single unit of the compressor  10  is disposed for the refrigeration cycle, however, the number of the compressors is not limited and plural compressor may be provided. In the aforementioned case, the control unit  80  may be configured to execute the multiple control of as many as the provided compressors. 
     Embodiment 9 
     In the respective embodiments, the control units  80  and  80   a  control the opening of the on-off valves, drive frequency of the compressor  10 , the opening of the respective throttle devices and the three-way valves, however, it is not limited thereto. The control unit may be provided for each of the apparatuses. In the respective embodiments, a single temperature/humidity detection unit  81  is disposed at the inlet side of the air passage of the evaporator  70 , however, it is not limited thereto. For example, the temperature detection unit and the humidity detection unit may be separately provided, or plural units may be provided. The pressure detection units for detecting the refrigerant pressure may be provided adjacent to the respective apparatuses. 
     In the embodiments, the refrigeration cycle apparatuses  100  to  100   c  are applied to the refrigerator, room air-conditioner, all-in-one air conditioning system and the like, however, it is not limited thereto. For example, the refrigeration cycle apparatuses  100  to  100   c  may be applied to the refrigerated warehouse, humidifier, humidity control unit and the like. The type of the refrigerant, the air passage and the flow passage in the refrigeration cycle may be determined in accordance with the intended use and application.