Heat exchange system and application apparatus equipped with same

Abstract

A heat exchange system includes: a heat exchanger that exchanges heat between air and a heat transfer medium that flows inside the heat exchanger to cool the air; and a feeding member that holds an additive that reduces, when water in the air adheres to a surface of the heat exchanger, a contact angle of the water with respect to the surface. The additive contains a non-ionic surfactant. The feeding member feeds the additive to the surface. A concentration of the non-ionic surfactant in a liquid mixture is a value greater than or equal to a critical micelle concentration at 25°C, the liquid mixture being a mixture of the water adhering to the surface and the additive that has been fed to the surface.

Description

Technical Field

[0001] The present disclosure relates to a heat exchange system and applied equipment including the same, and particularly relates to a technique to prevent corrosion of a heat exchange system and to obtain excellent heat exchange efficiency.Background Art

[0002] A heat exchange system includes, for example, a heat exchanger that exchanges heat between air and a heat transfer medium. In a case where such a heat exchange system is used in a refrigeration apparatus or the like, when the heat exchanger is cooled as a result of the heat exchange, water in the air adheres to the surface of the heat exchanger. There are cases where the water is cooled and turns into frost or ice. Hereinafter, all of these may be simply referred to as "water".

[0003] When the water adheres to the surface of the heat exchanger, the heat exchange efficiency of the heat exchange system is reduced due to the influence of, for example, specific heat, thermal conductivity, latent heat, or sensible heat of the water. Also, when the water adheres to a plurality of fins of the heat exchanger, the gaps between the fins are sealed by the water. This hinders a flow of air between the fins, and consequently, the heat exchange efficiency of the heat exchange system is reduced.

[0004] Further, when the water adheres to the metal surface of the heat exchanger, it will cause corrosion of the surface of the heat exchanger. To address this problem, for example, Patent Literature 1 discloses a technique including: forming a resin film on the surface of a heat exchange mechanism to suppress deterioration of the heat exchange mechanism, the deterioration being due to the heat exchange mechanism coming into contact with, for example, condensation water in which corrosive gas in the atmosphere is dissolved; and mixing aluminum flakes in the resin film to suppress a reduction in heat exchange efficiency. Patent Literature 2 discloses a corrosion suppressing method in which an anti-corrosive agent is added to a water system, such as cooling water that comes into contact with copper-based members.Citation List Patent Literature

[0005] PTL 1: Japanese Laid-Open Patent Application Publication No. 2004-360069 PTL 2: Japanese Laid-Open Patent Application Publication No. 2015-193876 Summary of Invention Technical Problem

[0006] However, in the case of the technique of Patent Literature 1, it is necessary to select chemical components of the resin film in accordance with the type of the corrosive gas. There is also a case where the resin film deteriorates over time, which results in reduced heat exchange efficiency. In the case of the technique disclosed by Patent Literature 2, it is necessary to preselect a suitable corrosion inhibitor in accordance with an object for which corrosion is to be prevented.

[0007] In view of the above, an objective of the present disclosure is to make it possible to: even when water adheres to the surface of a heat exchanger in a heat exchange system, prevent corrosion of the heat exchanger with a relatively small workload; and obtain excellent heat exchange efficiency for a long term by facilitating water drainage from the heat exchanger.Solution to Problem

[0008] A heat exchange system according to one aspect of the present disclosure includes: a heat exchanger that exchanges heat between air and a heat transfer medium that flows inside the heat exchanger to cool the air; and a feeding member that holds an additive that reduces, when water in the air adheres to a surface of the heat exchanger, a contact angle of the water with respect to the surface. The additive contains a non-ionic surfactant. The feeding member feeds the additive to the surface. A concentration of the non-ionic surfactant in a liquid mixture is a value greater than or equal to a critical micelle concentration at 25°C, the liquid mixture being a mixture of the water adhering to the surface and the additive that has been fed to the surface.

[0009] According to the above configuration, the contact angle of the water adhering to the surface of the heat exchanger with respect to the surface is reduced by the additive fed from the feeding member, and thereby the surface of the heat exchanger is hydrophilized. Since the concentration of the non-ionic surfactant in the liquid mixture is a value greater than or equal to the critical micelle concentration at 25°C, the surface tension of the liquid mixture on the surface of the heat exchanger is reduced, and thereby the surface of the heat exchanger is highly hydrophilized. Consequently, the wettability of the surface of the heat exchanger is increased, and the surface area of a water film formed on the surface of the heat exchanger is increased. This makes it possible to increase the drying rate and to quickly drain the water from the surface of the heat exchanger. As a result, corrosion of the heat exchange system and a reduction in the heat exchange efficiency of the heat exchange system, both due to the water adhering to the surface of the heat exchanger, can be prevented.

[0010] Since the surface tension of the liquid mixture on the surface of the heat exchanger is reduced and the surface of the heat exchanger is highly hydrophilized, the liquid removal performance of the surface of the heat exchanger can be improved, and the amount of water to be dried can be reduced from the initial stage of drying. This makes it possible to prevent a situation where water adheres to the surface of the heat exchanger for a long period of time, and consequently, for example, corrosion of the surface of the heat exchanger progresses due to oxygen diffusion in the water film.

[0011] These advantageous effects are obtained by modifying, with use of the additive, the properties of the water adhering to the surface of the heat exchanger without direct surface treatment on the surface of the heat exchanger. Therefore, for example, it is not necessary to: form a resin film on the surface of the heat exchanger; replace the resin film before it deteriorates; and preselect an anti-corrosive agent for each object for which corrosion is to be prevented. Consequently, in the heat exchange system, even if water adheres to the surface of the heat exchanger, corrosion of the heat exchanger is prevented with a relatively small workload, and water drainage from the heat exchanger is facilitated, which makes it possible to obtain excellent heat exchange efficiency for a long term.

[0012] The concentration of the non-ionic surfactant in the liquid mixture may be a value within a range greater than or equal to 100 ppm. This makes it possible to readily set the concentration of the non-ionic surfactant to a value greater than or equal to the critical micelle concentration.

[0013] The heat exchanger may further include: a plurality of fins; and a flow tube that is in contact with the plurality of fins and through which the heat transfer medium flows. Surface positions, on the heat exchanger, to which the additive is fed may include a lower end of at least one of the plurality of fins and / or a gap of at least one of the plurality of fins, the gap being formed between the flow tube and a fin collar of the at least one fin, the fin collar being a contact portion where the at least one fin is in contact with the flow tube. The heat exchange system may further include: a fixing member that fixes the feeding member to the heat exchanger; and a drain pan that receives water that falls from the surface. Surface positions, on the heat exchanger, to which the additive is fed may include a contact position where the heat exchanger is in contact with the fixing member and / or a facing position where the heat exchanger faces the drain pan. This consequently makes it possible to, for example, favorably prevent corrosion at positions, on the surface of the heat exchanger, where corrosion tends to relatively easily occur.

[0014] The feeding member may contain: a plurality of carriers, each of which carries the additive; and a support that supports the plurality of carriers in a dispersed state, such that the additive is releasable from the carriers to outside of the feeding member.

[0015] According to the above configuration, since the additive is carried by the plurality of dispersed carriers, the additive can be readily fed from the carriers to the water adhering to the surface of the heat exchanger over a wide area. The support supports the plurality of carriers in such a manner that the additive is releasable from the plurality of carriers to the outside of the feeding member. This makes it possible to stably feed the additive from the feeding member to the surface of the heat exchanger while supporting the carriers.

[0016] Each of the carriers may be a porous granular material. Accordingly, the additive in an ample amount is loaded into the pores of the carriers, and the additive is gradually released from the feeding member to the surface of the heat exchanger. This makes it possible to feed the additive to the water adhering to the surface of the heat exchanger for a long term from the initial stage of driving of the heat exchange system.

[0017] The additive may dissolve, disperse, or diffuse in the water adhering to the surface. Accordingly, the additive from the feeding member can be quickly spread within the water adhering to the surface of the heat exchanger.

[0018] Applied equipment according to one aspect of the present disclosure includes any of the above-described heat exchange systems. The applied equipment may be a refrigeration apparatus that refrigerates or freezes an object to be refrigerated or frozen. The applied equipment may be an air conditioner including an outdoor unit, and the heat exchanger and the feeding member may be disposed in the outdoor unit.Advantageous Effects of Invention

[0019] According to each of the above-described aspects of the present disclosure, in the heat exchange system, even if water adheres to the surface of the heat exchanger, corrosion of the heat exchanger is prevented with a relatively small workload, and water drainage from the heat exchanger is facilitated, which makes it possible to obtain excellent heat exchange efficiency for a long term.Brief Description of Drawings

[0020] FIG. 1 is a front view of applied equipment according to Embodiment 1. FIG. 2 is a schematic diagram showing a state where a feeding member of FIG. 1 feeds an additive to water adhering to the surface of a heat exchanger. FIG. 3 is an enlarged view showing an internal structure of the feeding member of FIG. 1. Each of FIGS. 4A to 4C schematically shows the state of the surface of a conventional heat exchanger and the vicinity of the surface before and after water removal from the surface, FIG. 4A showing the state where water adheres to the surface of the heat exchanger, FIG. 4B showing the state where a thick water film is formed by the water adhering to the surface of the heat exchanger and the state where the water remains on a fin, FIG. 4C showing the state where frost is deposited on the surface of the heat exchanger. Each of FIGS. 5A to 5C schematically shows the state of the surface of the heat exchanger and the vicinity of the surface before and after water removal from the surface according to Embodiment 1, FIG. 5A showing the state where water adheres to the surface of the heat exchanger, FIG. 5B showing the state where a thin water film is formed on the surface of the heat exchanger and the water falls (slides down) from the surface, FIG. 5C showing the surface of the heat exchanger, from which the water has been drained. FIG. 6 is a schematic diagram showing applied equipment according to Embodiment 2. FIG. 7 is a graph showing a relationship between a surfactant concentration (ppm) and the contact angle (°) of water (liquid mixture) in Test 1. FIG. 8 is a photograph showing the state of a sample of Example 1 when a corrosion solution for Example was sprayed on the sample in Test 2. FIG. 9 is a photograph showing the state of a sample of Comparative Example 1 when a corrosion solution for Comparative Example was sprayed on the sample in Test 2. FIG. 10 is a photograph showing the state of corrosion of the sample of Example 1 in Test 2, in which the maximum erosion depth is 93 µm. FIG. 11 is a photograph showing the state of corrosion of the sample of Comparative Example 1 in Test 2, in which the maximum erosion depth is 373 µm. Description of Embodiments

[0021] Hereinafter, embodiments are described with reference to the drawings.(Embodiment 1)[Applied Equipment and Heat Exchange System]

[0022] FIG. 1 is a front view of applied equipment 1 according to Embodiment 1. FIG. 2 is a schematic diagram showing a state where a feeding member 6 of FIG. 1 feeds an additive to water adhering to the surface of a heat exchanger 3. The applied equipment 1 shown in FIG. 1 is, as one example, a refrigeration apparatus that refrigerates or freezes an object to be refrigerated or frozen. The applied equipment 1 includes a heat exchange system 2 and a casing 7. The casing 7 includes therein a plurality of interior spaces S1 to S4. Examples of the interior spaces S1 to S4 include refrigerating compartments, freezing compartments, and vegetable compartments. The heat exchange system 2 includes the heat exchanger (evaporator) 3, a defrosting mechanism 4, and a controller 5. The heat exchange system 2 further includes a compressor 11, a condenser 12, and a fan 14.

[0023] The heat exchange system 2 exchanges heat between air in the interior spaces S1 to S4 and a heat transfer medium to generate cool air. The heat exchanger 3 comes into contact with the water-containing air in the interior spaces S1 to S4, and exchanges heat between the air and the heat transfer medium that flows within the heat exchanger 3, thereby cooling the air. The heat exchanger 3 includes: a plurality of fins 31; and a flow tube 30, which is in contact with the plurality of fins 31 and through which the heat transfer medium flows. The plurality of fins 31 cause the heat transfer medium in the flow tube 30 to exchange heat with the air. As one example, the plurality of fins 31 extend in the vertical direction, and are arranged to be spaced apart from each other in a crossing direction that crosses the vertical direction (the crossing direction in this example is the horizontal direction). Each fin 31 contains, as one example, a metal material that has excellent thermal conductivity (e.g., aluminum). However, the material of the fins 31 is not limited to this example. The plurality of fins 31 are fixed to the flow tube 30 by a fixing technique, such as brazing or tube expansion. The flow tube 30 allows the heat transfer medium to flow therethrough. The plurality of fins 31 are thermally coupled to the flow tube 30. As one example, fins 31 adjacent to each other have surfaces parallel to each other. Each fin 31 includes fin collars 31c, each fin collar 31c being a contact portion where the fin 31 is in contact with the flow tube 30. The fin collars 31c improve adhesion between the flow tube 30 and the fin 31. As one example, each fin collar 31c is formed by bending a part of the fin 31 along the outer peripheral surface of the flow tube 30. Accordingly, each fin collar 31c is in surface contact with the outer peripheral surface of the flow tube 30.

[0024] The heat exchange system 2 further includes: fixing members 16, which fix the feeding member 6 to the heat exchanger 3; and a drain pan 17, which receives water that falls from the surface of the heat exchanger 3. As one example, the fixing members 16 include fastening members. With the fixing members 16, the feeding member 6 is detachably fixed to the heat exchanger 3. The fixing members 16 are not limited to this example. As another example, the fixing members 16 may include adhesive members. The drain pan 17 is disposed below the heat exchanger 3. As one example, the drain pan 17 is disposed in a manner to cover the bottom of all the fins 31 so that the drain pan 17 will properly receive water that falls from each fin 31. However, this is a non-limiting example.

[0025] The compressor 11 compresses the heat transfer medium that has passed though the heat exchanger 3 and that is in a liquid state. The condenser 12 cools the heat transfer medium that is fed from the compressor 11 and that is in a gaseous state to liquefy the heat transfer medium, and causes the liquefied heat transfer medium to flow to the heat exchanger 3. The fan 14 causes the air in the interior spaces S1 to S4 and the air in the vicinity of the heat exchanger 3 to circulate.

[0026] The defrosting mechanism 4 melts frost adhering to the surface of the heat exchanger 3, thereby defrosting the frost. Examples of what is to be defrosted by the defrosting mechanism 4 include not only frost and ice that adhere to the surface of the heat exchanger 3 while the heat exchange system 2 is being driven, but also frost, snow, and ice that have entered the inside of the applied equipment 1 from the outside, for example, in a use environment of the applied equipment 1 in a cold region. Hereinafter, all of these may be simply referred to as "frost".

[0027] As one example, the defrosting mechanism 4 is of a heater type, and includes a defrosting heater 13. During defrosting operation of the applied equipment 1, air around the heat exchanger 3 is warmed up by the defrosting heater 13 to turn into warm air, and the warm air flows by convection. As a result of the warm air coming into contact with the surface of the heat exchanger 3, the frost is defrosted. The frost on the surface of the heat exchanger 3 is defrosted also by, for example, radiant heat from the defrosting heater 13. When performing the defrosting, the defrosting mechanism 4 of the present embodiment adjusts the temperature of the surface of the heat exchanger 3 to a temperature not lower than the melting point of the water adhering to the surface of the heat exchanger 3. The defrosting mechanism 4 is not limited to the heater type, but may be any other known type, for example, a hot gas type, water-spraying type, or off-cycle type.

[0028] The heat exchange system 2 further includes a defrosting temperature detector 15. The defrosting temperature detector 15 detects whether or not a tube temperature of the heat exchange system 2 (e.g., the temperature of the flow tube 30) has reached a predetermined temperature at which the defrosting operation of the defrosting mechanism 4 is to be ended. As one example, the defrosting temperature detector 15 includes a known temperature sensor.

[0029] The controller 5 controls the compressor 11, the defrosting heater 13, the fan 14, and a valve that adjusts the flow rate of the flow tube 30, separately from each other. As one example, the controller 5 has a timer function. With the timer function, the controller 5 automatically drives the defrosting mechanism 4 each time cooling operation of the applied equipment 1 has continued for a predetermined period of time (e.g., 13 hours). The controller 5 receives an input of a detection signal from the defrosting temperature detector 15. As one example, based on the detection signal from the defrosting temperature detector 15, the controller 5 automatically stops driving the defrosting mechanism 4. The controller 5 of the present embodiment is realized by a computer that includes: processors, such as a CPU; and storage media, such as a ROM and RAM. The storage media store therein a plurality of control programs including: a heat exchanger control program for the CPU to control the valve, the compressor 11, the fan 14, and so forth; and a defrosting control program for controlling the defrosting mechanism 4 when performing defrosting operation. In a case where the applied equipment 1 includes a pump to cause the heat transfer medium to flow through the flow tube 30 of the heat exchanger 3, the controller 5 may control the pump.

[0030] The heat exchange system 2 includes at least one feeding member 6. The feeding member 6 holds an additive that reduces the contact angle of water adhering to the surface of the heat exchanger 3 with respect to the surface. The additive facilitates spreading of a water film formed on the surface of the heat exchanger 3, thereby making the water film thin. The feeding member 6, for example, comes into contact with water contained in the atmosphere, thereby releasing the additive to the outside in such a manner that the additive is dispersed into the water. In this manner, the additive is fed from the feeding member 6 to the surface of the heat exchanger 3. As one example of the additive feeding manner, the additive is fed, by free fall, to the water adhering to the surface of the heat exchanger 3. The feeding of the additive may be performed at any timing. In the heat exchange system 2, the additive is gradually released from the feeding member 6 so that the additive will be fed to the water adhering to the surface of the heat exchanger 3 over a predetermined period (e.g., for several years).

[0031] As one example, the feeding member 6 has an elongated shape, and is disposed in contact with the surface of the heat exchanger 3 (e.g., the end surface of each fin 31). In the present embodiment, the feeding member 6 is strip-shaped, and is disposed such that the longitudinal direction of the feeding member 6 extends along the arrangement direction of the plurality of fins 31. Since the feeding member 6 is detachably fixed to the heat exchange system 2 by the fixing members 16, the feeding member 6 can be replaced at a predetermined timing. The heat exchange system 2 of the present embodiment includes a plurality of feeding members 6 that are arranged in such a manner that they are spaced apart from each other. Each feeding member 6, extending in the thickness direction of the plurality of fins 31 of the heat exchanger 3, is in contact with the end surface of each fin 31.

[0032] The applied equipment 1 herein is a refrigeration apparatus. Therefore, while the applied equipment 1 (the heat exchange system 2) is being driven, the surface of the heat exchanger 3 is cooled to a temperature below the freezing point as a result of exchanging heat with the heat transfer medium. However, in the applied equipment 1, the defrosting mechanism 4 is driven at the time of performing defrosting operation, and consequently, the atmosphere of the feeding member 6 is warmed up. As a result of the atmosphere of the feeding member 6 turning into a high-temperature and high-humidity state or as a result of water adhering to the feeding member 6, the additive in the feeding member 6 comes into contact with water. Consequently, in the heat exchange system 2, the additive can be fed from the feeding member 6 to the surface of the heat exchanger 3.

[0033] It should be noted that, during the applied equipment 1 being driven, there is a case where the feeding member 6 freezes while containing water from the air. In this case, in the applied equipment 1, at the time of performing defrosting operation, the defrosting mechanism 4 is driven, and thereby the atmosphere of the feeding member 6 turns into a high-temperature and high-humidity state. Consequently, the ice of water contained in the feeding member 6 melts. Thus, even in a case where the feeding member 6 freezes during the applied equipment 1 being driven, the additive can be fed from the feeding member 6 to the surface of the heat exchanger 3.[Specific Example of Feeding member]

[0034] FIG. 3 is an enlarged view showing an internal structure of the feeding member 6 of FIG. 1. As shown in FIG. 3, the feeding member 6 contains: a plurality of carriers 60, each of which carries the additive; and a support 61, which supports the plurality of carriers 60 in a dispersed state, such that the additive is releasable from the carriers 60 to the outside of the feeding member 6.

[0035] In the present embodiment, each of the carriers 60 is a porous granular material. The external diameter of the granular material can be suitably set to, for example, a value of several µm. Further, as one example, the pore volume of the granular material can be set to a value of several mL / g; the pore diameter of the granular material can be set to a value of about a dozen of nm; and the specific surface area of the granular material can be set to a value of several hundreds of m 2< / g. The grain diameter, specific surface area, and pore diameter of the granular material are set to respective values that are suitable for, for example, achieving the graduality in releasing the additive, which the feeding member 6 is required to have. As one example, each carrier 60 is made of the porous granular material, which makes it possible to load the additive in an ample amount into the carrier 60. In the present embodiment, the carrier 60 contains an inorganic component. As one example, the carrier 60 is made of porous glass containing glass such as amorphous silica. For example, the material of the carrier 60 may be at least one of the following: porous glass, activated carbon, zeolite, and porous concrete.

[0036] The support 61 of the present embodiment contains a water-insoluble component. As one example, the water-insoluble component is a water-insoluble resin. For example, the water-insoluble resin may be at least one of the following: polyethylene, polypropylene, polyamide, polyethylene terephthalate, polybutylene terephthalate, and acrylic-modified polyethylene (e.g., "Acryft" available from Sumitomo Chemical Company, Limited.).

[0037] In the feeding member 6, the gaps between the plurality of carriers 60 are filled with the support 61. Accordingly, the plurality of carriers 60 are supported by the support 61 in a state where they are in contact with or spaced apart from each other. When the feeding member 6 comes into contact with water, for example, the additive is fed from the carriers 60 positioned in a surface layer of the feeding member 6, and dissolves into the water. As a result, the concentration of the additive in the carriers 60 in the surface layer decreases. Thereafter, the additive shifts from the carriers 60 positioned at the inner side of the feeding member 6 toward the carriers 60 positioned in the surface layer of the feeding member 6, and consequently, the concentration of the additive in the carriers 60 in the surface layer increases. Then, the additive in the carriers 60 in the surface layer dissolves into the water again. This phenomenon repeats, and thereby the additive is fed from the feeding member 6 to the water outside. As the additive, any additive that can reduce the contact angle of water adhering to the surface of the heat exchanger 3 with respect to the surface of the heat exchanger 3 can be suitably selected. As one example, the additive contains a surfactant. The surfactant herein is a nonionic surfactant. This surfactant includes a hydrophilic group and a hydrophobic group in its molecular structure.

[0038] Examples of the nonionic surfactant include oxyalkylene alkyl ether-based surfactants, such as fatty acid glycerin ester, fatty acid sorbitan ester, fatty acid sucrose ester, alkyl polyglucoside, polyoxyethylene propylene alkyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene polyoxypropylene glycol. The surfactant is not limited to these examples. Any suitable surfactant can be selected in accordance with, for example, the object in which the surfactant is used, the environment in which the surfactant is used, etc.

[0039] As one example, the feeding member 6 contains: 20% by weight or more and 50% by weight or less of the support 61; 10% by weight or more and 30% by weight or less of the carriers 60; and a composition formed from the remainder. The additive is contained in the remainder. The composition ratio of the feeding member 6 is not limited to this example.

[0040] When the additive is fed to water adhering to the surface of a plurality of heat exchangers 3, the additive can favorably reduce the aforementioned contact angle, and the additive can diffuse over a wide area of the surface of each heat exchanger 3. These advantageous effects are further enhanced by containing the non-ionic surfactant in the additive. The additive can contain not only the surfactant, but also, for example, a water-soluble organic solvent. Examples of the organic solvent include alcohols, ketones, esters, and ethers. Among these, for example, a lower alcohol is preferable. Examples of the lower alcohol include ethanol, propanol, isopropyl alcohol, and butanol.

[0041] The additive of the present embodiment dissolves, disperses, or diffuses in the water adhering to the surface of the heat exchanger 3. Accordingly, for example, even in a direction crossing the vertical direction, the additive from the feeding member 6 can be quickly spread within the water adhering to the surface of the heat exchanger 3. As one example, the additive of the present embodiment contains only the surfactant.

[0042] In the present embodiment, the concentration of the non-ionic surfactant in a liquid mixture of the water adhering to the surface of the heat exchanger 3 and the additive fed to the surface of the heat exchanger 3 is a value greater than or equal to the critical micelle concentration (CMC) at 25°C. The critical micelle concentration herein refers to the concentration at which an initial micelle is formed in a solution. As one example, the concentration of the non-ionic surfactant in the liquid mixture is set to a value within a range greater than or equal to 100 ppm. With this setting, the concentration of the non-ionic surfactant in the liquid mixture is adjusted to modify the properties of the liquid mixture so that, on the surface of the heat exchanger 3, a very thin water film suitable for water drainage and drying can be formed.

[0043] Further, in the present embodiment, the feeding of the additive to the surface of the heat exchanger 3 is facilitated toward positions where water tends to accumulate for the structural reasons and where the surface of the heat exchanger 3 tends to be corroded by the water. As a specific example, in the present embodiment, the heat exchanger 3 includes the plurality of fins 31 and the flow tube 30. Each fin 31 includes the fin collars 31c. Accordingly, surface positions, on the heat exchanger 3, to which the additive is fed include a lower end 31a of at least one of the plurality of fins 31 and / or a gap G of at least one of the plurality of fins 31, the gap G being formed between the flow tube 30 and each fin collar 31c.

[0044] The heat exchange system 2 of the present embodiment further includes the fixing members 16 and the drain pan 17. Accordingly, the surface positions, on the heat exchanger 3, to which the additive is fed include any or all of contact positions where the heat exchanger 3 is in contact with the fixing members 16 and / or any or all of facing positions 3 1b where the heat exchanger 3 faces the drain pan 17. In the present embodiment, the lower ends 31a partly overlap the respective facing positions 31b.

[0045] Next, an example of a method of manufacturing the feeding member 6 is described. As one example, the carriers 60, the support 61, and the additive are heat-kneaded to form a strand. The strand is cut into predetermined dimensions, and then the cut piece is subjected to injection molding to obtain the feeding member 6 in a desired shape. In a case where the feeding member 6 is manufactured by injection molding, the shape and size of the feeding member 6 can be readily set in accordance with, for example, the shape of the heat exchanger 3 and the internal space of the heat exchange system 2. In a case where the feeding member 6 is thus manufactured by heat-kneading and injection-molding the materials, the material of the carriers 60 preferably has sufficient strength to withstand the kneading, and preferably has thermal resistance within a temperature range for the injection molding. The material of the support 61 and the material of the additive are also preferably those having thermal resistance within the temperature range for the injection molding.

[0046] The shape of the feeding member 6 is not limited to an elongated shape, but may be, for example, a spherical shape such as an elliptical spherical shape or a rectangular parallelepiped shape. For example, the additive can be efficiently diffused over a wide area of the surface of each heat exchanger 3 by disposing the cylindrical feeding member 6 on top of the heat exchanger 3 such that the longitudinal direction of the feeding member 6 extends along the arrangement direction of the plurality of fins 31.

[0047] The feeding member 6 may contain other component(s). For example, the other component(s) may be at least one of the following: surfactants different from the surfactant of the above-described additive, esters, salts, defoaming agents, viscosity modifiers, fragrances, colorants, pH control agents, antioxidants, and inorganic substances such as talc and silica. However, these are non-limiting examples. Further, the number of feeding members 6 included in the heat exchange system 2 is not particularly limited.[Driving Heat Exchange System and Applied Equipment]

[0048] When the applied equipment 1 performs cooling operation, the heat transfer medium that is discharged from the heat exchanger 3 and that is in a gaseous state is compressed by the compressor 11 into a high-temperature and high-pressure state, and is then fed to the condenser 12. As a result of being cooled by the condenser 12, the gaseous heat transfer medium turns into a liquid heat transfer medium. The liquid heat transfer medium flows through a capillary tube that is separately included in the applied equipment 1 to turn into a low-temperature and low-pressure state, and is then fed to the heat exchanger 3.

[0049] By driving the fan 14, the air in the interior spaces S1 to S4 is fed to the vicinity of the heat exchanger 3 to come into contact with the plurality of fins 31. Consequently, the air around the heat exchanger 3 exchanges heat, via the plurality of fins 31, with the heat transfer medium flowing inside the heat exchanger 3, thereby turning into cool air. By driving the fan 14, the cool air is fed to the interior spaces S1 to S4 and used to cool an object to be cooled. After flowing through the flow tube 30, the heat transfer medium that has been used for the heat exchange is fed to the compressor 11 again.

[0050] The air in the interior spaces S1 to S4 contains water. The surface of the heat exchanger 3, which has been cooled by the heat exchange between the air and the heat transfer medium, comes into contact with the water-containing air, and as a result, water adheres to the surface of the heat exchanger 3. This water condenses into water droplets. When these water droplets are further cooled by the heat exchanger 3, they freeze into ice. The water droplets that have frozen into ice cumulatively adhere to the surface of the heat exchanger 3, and as a result, frost adheres to the surface of the heat exchanger 3.

[0051] In conventional art, when water adheres to the surface of the heat exchanger, the surface of the heat exchanger corrodes, and also, the heat exchange efficiency of the heat exchanger is reduced due to the influence of, for example, specific heat, thermal conductivity, latent heat, or sensible heat of the water. Further, when the gaps between the fins 31 are sealed by the water, a flow of air inside the heat exchanger is hindered, and consequently, the heat exchange efficiency of the heat exchanger is reduced.

[0052] In the heat exchange system 2 of the present embodiment, as a result of the atmosphere of the feeding member 6 turning into a high-temperature and high-humidity state or as a result of water adhering to the feeding member 6, the additive of the feeding member 6 comes into contact with the water. Consequently, the additive is fed from the feeding member 6 to the surface of the heat exchanger 3. With use of the additive, the contact angle of the water with respect to the surface of the heat exchanger 3 is reduced. In the heat exchange system 2, the additive contains a non-ionic surfactant, and the concentration of the non-ionic surfactant in the liquid mixture is set to a value greater than or equal to the critical micelle concentration at 25°C. As a result, surface tension (in other words, surface energy) of the liquid mixture is reduced, and the surface of the heat exchanger 3 is highly hydrophilized. Consequently, the wettability of the heat exchanger 3 is increased, and the surface area of the water film is increased, which increases the drying rate of the water. Moreover, since the liquid removal performance of the surface of the heat exchanger 3 is improved, even in a case where the water droplets are significantly small, the water droplets easily fall from the surface of the heat exchanger 3. Therefore, for example, even when the water droplets adhere to a fin 31, the water droplets can be caused to easily fall from the lower end 31a of the fin 31. Consequently, the water is drained from the surface of the heat exchanger 3 at an early stage.

[0053] Since the wettability of the surface of the heat exchanger 3 is increased, a very thin water film of the liquid mixture is formed on the surface of the heat exchanger 3. Consequently, the amount of water adhering to the surface of the heat exchanger 3 is reduced from the drying process. This makes it possible to prevent a situation where the water adheres to the surface of the heat exchanger 3 for a long period of time, and consequently, corrosion of the surface of the heat exchanger 3 occurs and the heat exchanger effectiveness of the heat exchange system 2 is reduced.

[0054] Generally speaking, in a case where a thin water film is formed on a metal surface, it is conceivable that the oxygen component in the atmosphere is diffused into the water film, so that the amount of diffused oxygen in the water film increases, which allows corrosion of the metal surface to progress easily. However, in the present embodiment, even if a thin water film is formed on the surface of the heat exchanger 3, since the water is drained from the surface of the heat exchanger 3 at an early stage, the wet state of the surface of the heat exchanger 3 is less likely to continue, and for this reason, the aforementioned corrosion progress can be avoided. In other words, a wetting time that is a time during which the corrosion of the surface of the heat exchanger 3 progresses can be shortened. This consequently makes it possible to favorably prevent corrosion of the surface of the heat exchanger 3.

[0055] There may be a case where a thin water film is formed on the surface of the heat exchanger 3, which causes impurities in the air to adhere to the surface of the heat exchanger 3. Even in this case, the impurities are quickly drained out together with the water film, and thus the surface of the heat exchanger 3 can be kept in a clean condition. Further, since water drainage from around the heat exchanger 3 is facilitated, an unnecessary increase in the humidity inside the heat exchange system 2 can be suppressed. This makes it possible to suppress the formation of an internal environment of the heat exchange system 2 where corrosion tends to occur.

[0056] If the controller 5 determines that the cooling operation of the applied equipment 1 has continued for the predetermined period of time, the controller 5 controls the defrosting mechanism 4 to start defrosting operation. As one example, the defrosting mechanism 4 heats the air around the heat exchanger 3 by the defrosting heater 13, and causes a flow of the heated air by convection inside the casing 7. As a result, the frost on the surface of the heat exchanger 3 comes into contact with the heated air and melts. Further, as one example, the defrosting mechanism 4 melts the frost on the surface of the heat exchanger 3 by radiant heat from the defrosting heater 13. In the present embodiment, as described above, since a very thin water film is formed on the surface of the heat exchanger 3, the amount of water adhering to the surface of the heat exchanger 3 can be reduced. Therefore, even in a case where the water film freezes on the surface of the heat exchanger 3, when the defrosting mechanism 4 is driven, the water film melts, and the water is drained from the surface of the heat exchanger 3 at an early stage.

[0057] After the defrosting operation by the defrosting mechanism 4 has continued, when the controller 5 determines based on a detection signal from the defrosting temperature detector 15 that the tube temperature of the heat exchange system 2 has reached the predetermined temperature, the controller 5 stops the defrosting mechanism 4. Thereafter, the controller 5 controls the valve, the compressor 11, the fan 14, etc. to start re-cooling operation.(Details on Effects of Additive)

[0058] Each of FIGS. 4A to 4C schematically shows the state of the surface of a conventional heat exchanger (in this example, the surface of a fin) and the vicinity of the surface before and after water removal from the surface. As shown in FIGS. 4A to 4C, in a conventional refrigeration apparatus, when the surface of the heat exchanger is cooled by heat exchange between air and a heat transfer medium, water (condensation water) adheres to the surface (FIG. 4A). There is a case where the water freezes into frost due to factors such as a decrease in the temperature of the atmosphere and a decrease in the temperature of the surface of the heat exchanger.

[0059] As a result of the water adhering to the surface of the heat exchanger, a large number of water droplets and a thick water film are formed on the surface. Also, the water droplets accumulate on the lower end of the surface of the heat exchanger, such as the lower end of the fin (FIG. 4B). In a state where the water thus adheres to the fin, if the refrigeration apparatus performs re-cooling operation to re-cool the interior of the refrigeration apparatus to a preset temperature after defrosting operation, then the water re-freezes and remains as ice. In this case, frost further adheres on top of the ice, and thus the frost is cumulatively deposited (FIG. 4C). This consequently hinders normal heat exchange by the heat exchanger, and causes a reduction in the heat exchanger effectiveness of the refrigeration apparatus. In addition, due to the adhesion of the water, corrosion of the surface of the heat exchanger occurs.

[0060] Each of FIGS. 5A to 5C schematically shows the state of the surface of the heat exchanger 3 (in this example, the surface of a fin 31) and the vicinity of the surface before and after water removal from the surface according to Embodiment 1. As shown in FIGS. 5A to 5C, in the applied equipment 1, when water adheres to the surface of the heat exchanger 3 (FIG. 5A), a liquid mixture containing the water and the additive is produced on the surface of the heat exchanger 3. The properties of the water in the liquid mixture are modified by the additive fed from the feeding member 6. Water droplets that are adjacent to each other are easily combined together due to hydrophilicity, and fall (slide down) from the surface of the fin 31 due to their own weight. Even if these water droplets are minute droplets, since the surface tension of the water is reduced by the additive, these droplets easily fall from the surface of the fin 31. This realizes efficient water drainage from the surface of the fin 31 (FIG. 5B). Further, the properties of the water on the surface of the fin 31 are modified by the additive, and thereby the surface is hydrophilized. Consequently, the water widely spreads over the surface of the fin 31, and thereby a very thin water film is formed on the surface. Heat from the air in the atmosphere and heat from the fin 31 are easily transferred to the water film. As a result, the water drainage effect is further enhanced, and therefore, the water is quickly and almost entirely drained from the fin 31 (FIG. 5C).

[0061] According to the above-described applied equipment 1, excellent heat exchanger effectiveness of the applied equipment 1 can be obtained for a long term while preventing corrosion of the surface of the heat exchanger 3. This makes it possible to improve the power saving performance of the overall applied equipment 1. Further, since the cumulative frost deposition on the surface of the heat exchanger 3 is prevented, the amount of frost to be defrosted by performing the defrosting operation once can be reduced. This makes it possible to shorten the defrosting time. Since the amount of heat necessary for the defrosting is reduced, an increase in the temperature of the interior of the applied equipment 1 during the defrosting operation can be relatively suppressed. This makes it possible to suppress an increase in the temperature of an object to be refrigerated or frozen in the interior of the applied equipment 1. Further, the frequency of the defrosting operation can be reduced.

[0062] As described above, according to the heat exchange system 2 and the applied equipment 1, the contact angle of the water adhering to the surface of the heat exchanger 3 with respect to the surface is reduced by the additive fed from the feeding member 6, and thereby the surface of the heat exchanger 3 is hydrophilized. Since the concentration of the non-ionic surfactant in the liquid mixture is a value greater than or equal to the critical micelle concentration at 25°C, the surface tension of the liquid mixture on the surface of the heat exchanger 3 is reduced, and thereby the surface of the heat exchanger 3 is highly hydrophilized. Consequently, the wettability of the surface of the heat exchanger 3 is increased, and the surface area of a water film formed on the surface of the heat exchanger 3 is increased. This makes it possible to increase the drying rate and to quickly drain the water from the surface of the heat exchanger 3. As a result, corrosion of the heat exchange system 2 and a reduction in the heat exchange efficiency of the heat exchange system 2, both due to the water adhering to the surface of the heat exchanger 3, can be prevented.

[0063] Sine the surface tension of the liquid mixture on the surface of the heat exchanger 3 is reduced and the surface of the heat exchanger 3 is highly hydrophilized, the liquid removal performance of the surface of the heat exchanger 3 can be improved, and the amount of water to be dried can be reduced from the initial stage of drying. This makes it possible to prevent a situation where water adheres to the surface of the heat exchanger 3 for a long period of time, and consequently, for example, corrosion of the surface of the heat exchanger 3 progresses due to oxygen diffusion in the water film.

[0064] These advantageous effects are obtained by modifying, with use of the additive, the properties of the water adhering to the surface of the heat exchanger 3 without direct surface treatment on the surface of the heat exchanger 3. Therefore, for example, it is not necessary to: form a resin film on the surface of the heat exchanger 3; replace the resin film before it deteriorates; and preselect an anti-corrosive agent for each object for which corrosion is to be prevented. Consequently, in the heat exchange system 2, even if water adheres to the surface of the heat exchanger 3, corrosion of the heat exchanger 3 is prevented with a relatively small workload, and water drainage from the heat exchanger 3 is facilitated, which makes it possible to obtain excellent heat exchange efficiency for a long term.

[0065] In the present embodiment, the concentration of the non-ionic surfactant in the liquid mixture is a value within a range greater than or equal to 100 ppm. This makes it possible to readily set the concentration of the non-ionic surfactant to a value greater than or equal to the critical micelle concentration.

[0066] As one example, in the heat exchange system 2, the surface positions, on the heat exchanger 3, to which the additive is fed include the lower end 31a of at least one of the plurality of fins 31 and / or the gap G of at least one of the plurality of fins 31, the gap G being formed between the flow tube 30 and each fin collar 31c. In the heat exchange system 2, the surface positions, on the heat exchanger 3, to which the additive is fed may also include any or all of the contact positions where the heat exchanger 3 is in contact with the fixing members 16 and / or any or all of the facing positions 31b where the heat exchanger 3 faces the drain pan 17. This consequently makes it possible to, for example, favorably prevent corrosion at positions, on the surface of the heat exchanger 3, where corrosion tends to relatively easily occur.

[0067] The feeding member 6 contains: the plurality of carriers 60, each of which carries the additive; and the support 61, which supports the plurality of carriers 60 in a dispersed state, such that the additive is releasable from the carriers 60 to the outside of the feeding member 6.

[0068] According to the above configuration, since the additive is carried by the plurality of dispersed carriers 60, the additive can be readily fed from the carriers 60 to the water adhering to the surface of the heat exchanger 3 over a wide area. The support 61 supports the plurality of carriers 60 in such a manner that the additive is releasable from the plurality of carriers 60 to the outside of the feeding member 6. This makes it possible to stably feed the additive from the feeding member 6 to the surface of the heat exchanger 3 while supporting the carriers 60.

[0069] As one example, each carrier 60 is a porous granular material. Accordingly, the additive in an ample amount is loaded into the pores of the carriers 60, and the additive is gradually released from the feeding member 6 to the surface of the heat exchanger 3. This makes it possible to feed the additive to the water adhering to the surface of the heat exchanger 3 for a long term from the initial stage of driving of the heat exchange system 2.

[0070] The additive of the present embodiment dissolves, disperses, or diffuses in the water adhering to the surface of the heat exchanger 3. Accordingly, the additive from the feeding member 6 can be quickly spread within the water adhering to the surface of the heat exchanger 3.

[0071] It should be noted that in a case where the heat exchanger 3 is configured by using a copper pipe containing phosphorus, when a stress is applied to the heat exchanger 3, it may cause cracking on a corroded surface of the heat exchanger 3 (i.e., stress corrosion cracking). Also, in a case where the heat exchanger 3 is configured by using a stainless steel pipe, if chloride gas comes into contact with the surface of the heat exchanger 3, it may cause corrosion and cracking on the surface of the heat exchanger 3 (i.e., stress corrosion cracking). Further, in a case where the heat exchanger 3 is disposed inside the heat exchange system 2 at a location where an air flow tends to occur, chloride gas or other corrosive gas may come into contact with the surface of the heat exchanger 3. In these respects, according to the present embodiment, corrosion of the surface of the heat exchanger 3 is prevented as described above, which makes it possible to prevent such cracking. Hereinafter, Embodiment 2 is described focusing on differences from Embodiment 1.(Embodiment 2)

[0072] FIG. 6 is a schematic diagram showing applied equipment 101 according to Embodiment 2. The applied equipment 101 according to the present embodiment shown in FIG. 6 is an air conditioner, and includes a heat exchange system 102. The applied equipment 101 further includes an indoor unit 120 and an outdoor unit 121. The heat exchange system 102 includes: an indoor-side heat exchanger 103, which exchanges heat between indoor air and a heat transfer medium; an outdoor-side heat exchanger 106, which exchanges heat between outdoor air and the heat transfer medium; feeding members 6, each of which holds the above-described additive to be added to the outdoor-side heat exchanger 106; a defrosting mechanism 104, which defrosts the outdoor-side heat exchanger 106; and a controller 105. The indoor unit 120 includes the indoor-side heat exchanger 103. The outdoor unit 121 includes the outdoor-side heat exchanger 106, the feeding members 6, the defrosting mechanism 104, and the controller 105.

[0073] The heat exchange system 102 further includes a defrosting temperature detector 115, which detects whether or not a surface temperature of the outdoor-side heat exchanger 106 has reached a start temperature at which the defrosting mechanism 104 starts defrosting operation. The heat exchange system 102 further includes: a decompressor 107, which reduces the pressure of the heat transfer medium that is discharged from the indoor-side heat exchanger 103; and a compressor 111, which pressurizes the heat transfer medium that is discharged from the outdoor-side heat exchanger 106. The heat exchangers 103 and 106 are connected to each other by pipes R1 and R2. The heat transfer medium circulates through the heat exchangers 103 and 106 by flowing through the pipes R1 and R2. The controller 105 controls the defrosting mechanism 104. In the heat exchange system 102, the additive is fed from the feeding members 6 to the surface of the outdoor-side heat exchanger 106. As one example, the defrosting mechanism 104 is formed by the compressor 111 and the pipes R1 and R2. The controller 105 warms up the heat exchanger 106 by causing the applied equipment 101 to temporarily perform cooling operation.

[0074] As one example, the applied equipment 101 is heating equipment to heat indoors. During heating operation of the applied equipment 101, for example, in the indoor-side heat exchanger 103, the heat transfer medium that is flowing inside the indoor-side heat exchanger 103 and that is in a high-temperature and high-pressure gaseous state exchanges heat with low-temperature indoor air. As a result, the indoor air is warmed up. The heat transfer medium is discharged in a liquid state from the indoor-side heat exchanger 103, and is fed to the outdoor unit 121 through the pipe R2. The pressure of the heat transfer medium is reduced by the decompressor 107 in the outdoor unit 121, and fed to the outdoor-side heat exchanger 106. In the outdoor-side heat exchanger 106, the heat transfer medium turns into a gaseous state as a result of exchanging heat with outdoor air. This heat exchange causes a reduction in the surface temperature of the outdoor-side heat exchanger 106. The gaseous heat transfer medium is, after being discharged from the outdoor-side heat exchanger 106, compressed by the compressor 111 to turn into a high-temperature and high-pressure state, and is fed to the indoor unit 120 through the pipe R1. Thereafter, the heat transfer medium is used for heating the indoors again.

[0075] Here, the surface of the outdoor-side heat exchanger 106 that has been cooled by the heat transfer medium comes into contact with outdoor air containing water, and as a result, the water adheres to the surface of the outdoor-side heat exchanger 106. During heating operation of the applied equipment 101, the outdoor-side heat exchanger 106 exchanges heat between the outdoor air and the heat transfer medium, and is thereby cooled. Consequently, the water adhering to the surface of the heat exchanger 106 freezes into ice. The water that has frozen into ice cumulatively adheres to the surface of the heat exchanger 106, and as a result, frost adheres to the surface of the heat exchanger 106.

[0076] During heating operation of the applied equipment 101 of the present embodiment, when the amount of frost adhering to the surface of the heat exchanger 106 increases and the controller 105 determines based on a detection signal from the defrosting temperature detector 115 that the temperature detected by the defrosting temperature detector 115 has exceeded a threshold, the controller 105 controls the defrosting mechanism 104 to start defrosting operation, similar to the controller 5. As a result of the applied equipment 101 temporarily performing cooling operation, the defrosting mechanism 104 warms up the heat exchanger 106. Consequently, the frost adhering to the heat exchanger 106 melts. Also, the frost adhering to the feeding members 6 melts.

[0077] The heat exchange system 102 and applied equipment 101 configured as described above also provide the same advantageous effects as those provided by the heat exchange system 2 and applied equipment 1. That is, in a state where water adheres to the surface of the outdoor-side heat exchanger 106, the additive is fed from the feeding members 6 to the surface of the outdoor-side heat exchanger 106. As a result, on the surface of the outdoor-side heat exchanger 106, the contact angle of the water with respect to the surface of the outdoor-side heat exchanger 106 is reduced, and thereby wettability of the surface of the outdoor-side heat exchanger 106 is increased. Consequently, drainage of the water from the surface of the outdoor-side heat exchanger 106 is facilitated, and thus the water drainage effect is enhanced. Therefore, corrosion of the surface of the outdoor-side heat exchanger 106 and a reduction in the heat exchange efficiency of the heat exchange system 102, both due to the water, can be prevented. Since the additive is released gradually from the feeding members 6 to the surface of the outdoor-side heat exchanger 106, the additive in a sufficient amount can be kept held by the feeding members 6 for a long term. Consequently, in the heat exchange system 102 and applied equipment 101, corrosion of the surface of the outdoor-side heat exchanger 106 can be prevented, and also, excellent heat exchange efficiency can be obtained for a long term.

[0078] It should be noted that the applied equipment 101 driven as heating equipment is not limited to a type that uses a heat transfer medium. The applied equipment 101 may be, for example, a water heater of a heat pump type, hot-water heating equipment of a heat pump type, hot-water heating equipment using hot water supply, or heating equipment of a heat pump type dedicated for an electric vehicle (EV).(Confirmation Tests)

[0079] Next, confirmation tests on the present disclosure and results thereof are described. It should be noted that the present disclosure is not limited to configurations in Examples described below.[Test 1]

[0080] Based on a method described below, a relationship between the concentration of the non-ionic surfactant and the contact angle was looked into. First, as the non-ionic surfactant, "EMULGEN LS-106" available from Kao Corporation was used. An aqueous solution containing the surfactant was prepared as the above-described liquid mixture. The concentration of the surfactant in the aqueous solution was varied within the range of greater than or equal to 0 ppm and less than or equal to 1000 ppm. A droplet (5 µL) of the above aqueous solution was dropped on the surface of a pure aluminum plate, and the contact angle (°) was measured based on a tangent method. Measurement results are shown in Table 1. FIG. 7 is a graph showing a relationship between the surfactant concentration (ppm) and the contact angle (°) of the water (liquid mixture) in Test 1. [Table 1]Concentration (ppm)01020501002505001000Contact angle (°)95.585.279.557.64745.238.334.8

[0081] As shown in Table 1 and FIG. 7, the contact angle decreases rapidly in accordance with increase in the surfactant concentration from 0 ppm. It has been confirmed that, thereafter, when the surfactant concentration reaches a value within a range that is approximately greater than or equal to 100 ppm, the degree of decrease in the water contact angle is reduced. From this, it has been confirmed that in the case of this surfactant, when the surfactant concentration is within the range that is approximately greater than or equal to 100 ppm, the hydrophilizing effect of the aqueous solution (liquid mixture) is saturated.

[0082] Normally, the surface tension of the droplet is correlated with the contact angle of the droplet. It is considered that in a state where the contact angle of the droplet is saturated, the surface tension is also saturated. In a case where the surface tension of the solution containing the surfactant is saturated due to the concentration of the surfactant, it is considered that the surfactant concentration is greater than or equal to the critical micelle concentration. In the case of the surfactant used in this test, the critical micelle concentration at 25°C is considered to be approximately 100 ppm.[Test 2]

[0083] Next, with a method described below, the corrosion prevention effect provided by each of the above-described embodiments in a case where the heat exchanger is placed under conditions where corrosion due to water adhesion is facilitated was confirmed. As each of Example 1 and Comparative Example 1, a sample that is a partial cut out from the heat exchanger of the refrigerator "NR-F606WPX", which is applied equipment, available from Panasonic Corporation was used. Each sample includes a plurality of flow tubes 30 and a plurality of fins 31. The flow tubes 30 and the fins 31 are made of aluminum. Next, a corrosion solution for Comparative Example containing H 2 SO 4 -< (5 ppm), HCl (5 ppm), HNO 3 (5 ppm), and CH 3 COOH (50 ppm) was prepared. Also, a corrosion solution for Example was prepared by further containing a non-ionic surfactant (20000 ppm) in the corrosion solution for Comparative Example. As the non-ionic surfactant, "EMULGEN LS-106" available from Kao Corporation was used.

[0084] The corrosion solution for Example was sprayed on the sample of Example 1, and after the spraying, the sample was kept in a thermostatic chamber at 50°C for 20 minutes. This cycle of spraying the corrosion solution on the sample and then keeping the sample in the thermostatic chamber was repeatedly performed 500 times. Also, the corrosion solution for Comparative Example was sprayed on the sample of Comparative Example 1, and after the spraying, the sample was kept in the thermostatic chamber at 50°C for 20 minutes. This cycle of spraying the corrosion solution on the sample and then keeping the sample in the thermostatic chamber was repeatedly performed 500 times. In this manner, a cycle of condensation on the surface of the heat exchanger and drying of water on the surface of the heat exchanger was simulated, and thereby corrosion of the surface of the heat exchanger was facilitated.

[0085] FIG. 8 is a photograph showing the state of the sample of Example 1 when the corrosion solution for Example was sprayed on the sample in Test 2. FIG. 9 is a photograph showing the state of the sample of Comparative Example 1 when the corrosion solution for Comparative Example was sprayed on the sample in Test 2. As shown in FIG. 8, in the case of the sample of Example 1, it has been confirmed that a very thin smooth water film is formed on the surface of the heat exchanger. On the other hand, as shown in FIG. 9, in the case of the sample of Comparative Example 1, it has been confirmed that a large number of large and thick water droplets adhere to the surface of the heat exchanger.

[0086] After the above test, for each sample of Example 1 and Comparative Example 1, six segments were cut out from six different regions of the sample, respectively. Then, on the surface of each of the segments (No. 1 to 6) of Example 1 and the segments (No. 7 to 12) of Comparative Example 1, the degree of corrosion formed in a manner to erode the surface in the depth direction was checked, and the maximum corrosion depth (µm) was measured. Measurement results are shown in Tables 2 and 3. [Table 2]Segments of Example 1No. 1No. 2No. 3No. 4No. 5No. 6Maximum Corrosion Depth (µm)381174492793 [Table 3] Segments of Comp. Example 1No. 7No. 8No. 9No. 10No. 11No. 12Maximum Corrosion Depth (µm)96263373159179140

[0087] As shown in Table 2, in the case of the sample of Example 1, it has been confirmed that the value of the maximum corrosion depth is suppressed to fall within the range of greater than or equal to 11 µm and less than or equal to 93 µm. On the other hand, as shown in Table 3, in the case of the sample of Comparative Example 1, it has been confirmed that the value of the maximum corrosion depth reaches the range of greater than or equal to 96 µm and less than or equal to 373 µm. FIG. 10 is a photograph showing the state of corrosion of the sample of Example 1 in Test 2, in which the maximum erosion depth is 93 µm. FIG. 11 is a photograph showing the state of corrosion of the sample of Comparative Example 1 in Test 2, in which the maximum erosion depth is 373 µm. As shown in FIG. 10 and FIG. 11, it has been confirmed that in the case of the sample of Example 1, both the depth of the corrosion and the spreading of the corrosion are reduced as compared to the sample of Comparative Example 1. Specifically, it has been confirmed that in the case of the sample of Example 1, the depth of the corrosion is reduced to 1 / 4 or less as compared to the sample of Comparative Example 1.[Test 3]

[0088] Next, with a method described below, the corrosion prevention effect provided based on Embodiment 1 in a case where the applied equipment is a refrigeration apparatus (refrigerator) and the heat exchanger is placed under conditions where corrosion due to water adhesion is facilitated was confirmed by using a corrosion sensor of ACM (Atmospheric Corrosion Monitor) type (which may hereinafter be referred to as "ACM sensor"). As the ACM sensor, "Al-Ag ACM sensor" available from Syrinx Inc. was used.

[0089] As each of Example 2 and Comparative Example 2, the refrigerator "NR-F606WPX", which is applied equipment, available from Panasonic Corporation was used. In Example 2, the feeding member 6 was fixed to the upper part of the heat exchanger of the applied equipment. On the other hand, in Comparative Example 2, no feeding member 6 was mounted to the heat exchanger of the applied equipment. The ACM sensor was mounted to each of the heat exchanger of Example 2 and the heat exchanger of Comparative Example 2, and each of the applied equipment of Example 2 and the applied equipment of Comparative Example 2 was driven for about two weeks. While each applied equipment was being driven, a corrosion current flowing through the heat exchanger of each applied equipment was measured. Measurement results are shown in Table 4.

[0090] In Test 3, the concentration of the non-ionic surfactant in water drained from the heat exchanger, the non-ionic surfactant being derived from the feeding member 6, was within the range of greater than or equal to 200 ppm and less than or equal to 500 ppm, and on average, 340 ppm. From this, it has been confirmed that, in Example 2, the value of the concentration of the non-ionic surfactant in the liquid mixture on the surface of the heat exchanger was greater than or equal to the critical micelle concentration at 25°C. [Table 4]Unit of MeasurementComparative Example 2Example 2Corrosion RatemC / day9.473.79ng / day883354ng / cm 2< day356143µg / cm 2< year13052

[0091] In Table 4, a numerical value expressed in the unit "mC / day" is an actual measurement value of a corrosion electricity amount (unit: mC) flowing per day. A numerical value expressed in the unit "ng / day" is a calculated value of a weight reduction amount (ng) of a pure aluminum base material due to corrosion per day. A numerical value expressed in the unit "ng / cm 2< day" is a calculated value of a weight reduction amount (ng) of the pure aluminum base material per unit area (cm 2< ) thereof due to corrosion per day. A numerical value expressed in the unit "µg / cm 2< year" is a calculated value of a weight reduction amount (µg) of the pure aluminum base material per unit area (cm 2< ) thereof due to corrosion per year. Each of these calculated values was calculated as an AL weight corresponding to 1 / 3 of the electricity amount, based on the AL ion-electron ratio in AL atom ionization.

[0092] As shown in Table 4, it has been confirmed that, in the case of the applied equipment of Example 2, as compared to the applied equipment of Comparative Example 2, the corrosion rate of the corrosion caused by the water adhering to the surface of the heat exchanger can be reduced by half or more (reduced to about 40% or less). It should be noted that the corrosion current measured in Test 3 is the corrosion current due to forced galvanic corrosion between the Ag member used in the ACM sensor and the Al member of the heat exchanger used in the applied equipment. Therefore, an actual corrosion rate of the applied equipment is presumed to be lower than the corrosion rate of the applied equipment in Test 3.(Disclosure Items)

[0093] The following items disclose preferred embodiments of the heat exchange system and the applied equipment of the present disclosure.[Item 1]

[0094] A heat exchange system including: a heat exchanger that exchanges heat between air and a heat transfer medium that flows inside the heat exchanger to cool the air; and a feeding member that holds an additive that reduces, when water in the air adheres to a surface of the heat exchanger, a contact angle of the water with respect to the surface, wherein: the additive contains a non-ionic surfactant; the feeding member feeds the additive to the surface; and a concentration of the non-ionic surfactant in a liquid mixture is a value greater than or equal to a critical micelle concentration at 25°C, the liquid mixture being a mixture of the water adhering to the surface and the additive that has been fed to the surface.[Item 2]

[0095] The heat exchange system according to item 1, wherein the concentration of the non-ionic surfactant in the liquid mixture is a value within a range greater than or equal to 100 ppm.[Item 3]

[0096] The heat exchange system according to item 1 or 2, wherein the heat exchanger further includes: a plurality of fins; and a flow tube that is in contact with the plurality of fins and through which the heat transfer medium flows, and surface positions, on the heat exchanger, to which the additive is fed include a lower end of at least one of the plurality of fins and / or a gap of at least one of the plurality of fins, the gap being formed between the flow tube and a fin collar of the at least one fin, the fin collar being a contact portion where the at least one fin is in contact with the flow tube.[Item 4]

[0097] The heat exchange system according to any one of items 1 to 3, further including: a fixing member that fixes the feeding member to the heat exchanger; and a drain pan that receives water that falls from the surface, wherein surface positions, on the heat exchanger, to which the additive is fed include a contact position where the heat exchanger is in contact with the fixing member and / or a facing position where the heat exchanger faces the drain pan.[Item 5]

[0098] The heat exchange system according to any one of items 1 to 4, wherein the feeding member contains: a plurality of carriers, each of which carries the additive; and a support that supports the plurality of carriers in a dispersed state, such that the additive is releasable from the carriers to outside of the feeding member.[Item 6]

[0099] The heat exchange system according to item 5, wherein each of the carriers is a porous granular material.[Item 7]

[0100] The heat exchange system according to any one of items 1 to 6, wherein the additive dissolves, disperses, or diffuses in the water adhering to the surface.[Item 8]

[0101] Applied equipment including the heat exchange system according to any one of items 1 to 7.[Item 9]

[0102] The applied equipment according to item 8, wherein the applied equipment is a refrigeration apparatus that refrigerates or freezes an object to be refrigerated or frozen.[Item 10]

[0103] The applied equipment according to item 8, wherein the applied equipment is an air conditioner including an outdoor unit, and the heat exchanger and the feeding member are disposed in the outdoor unit.

[0104] The present disclosure is not limited to the above-described embodiments. Modifications, additions, or deletions can be made to the configurations and methods of the above-descried embodiments without departing from the scope of the present disclosure. The additive fed by the feeding member 6 may contain a plurality of chemical components. In a case where the additive contains a plurality of chemical components, for example, the additive may contain: a first component having a function of reducing the contact angle of the water with respect to the surface of the heat exchanger; and a second component that activates the function of the first component to reduce the contact angle.

[0105] The feeding member 6 may be disposed in any manner, so long as the feeding member 6 can feed the additive to the water adhering to the surface of the heat exchanger. Accordingly, for example, the feeding member 6 may be disposed such that it is spaced apart from the surface of the heat exchanger. In this case, the additive from the feeding member 6 may be dropped onto the water adhering to the surface of the heat exchanger, or the additive may be fed via an additional member different from the feeding member 6.

[0106] Each of the applied equipment 1 and 101 is not limited to a configuration to automatically start the defrosting operation. For example, the defrosting operation may be started in accordance with an instruction from a user. In this case, when the user performs, on an inputter included in the applied equipment 1, an input to give a defrosting operation instruction, the controller 5 may control the defrosting mechanism 4 to start the defrosting operation. The heat exchange system 102 may include, in the indoor unit 120, the feeding member 6 holding the additive that reduces the contact angle of water adhering to the surface of the indoor-side heat exchanger 103 with respect to the surface.Reference Signs List

[0107] 1, 101applied equipment 2, 102heat exchange system 3heat exchanger 6feeding member 16fixing member 17drain pan 31cfin collar 60carrier 61support 103indoor-side heat exchanger (heat exchanger) 106outdoor-side heat exchanger (heat exchanger) 121outdoor unit

Claims

1. A heat exchange system comprising: a heat exchanger that exchanges heat between air and a heat transfer medium that flows inside the heat exchanger to cool the air; and a feeding member that holds an additive that reduces, when water in the air adheres to a surface of the heat exchanger, a contact angle of the water with respect to the surface, wherein: the additive contains a non-ionic surfactant; the feeding member feeds the additive to the surface; and a concentration of the non-ionic surfactant in a liquid mixture is a value greater than or equal to a critical micelle concentration at 25°C, the liquid mixture being a mixture of the water adhering to the surface and the additive that has been fed to the surface.

2. The heat exchange system according to claim 1, wherein the concentration of the non-ionic surfactant in the liquid mixture is a value within a range greater than or equal to 100 ppm.

3. The heat exchange system according to claim 1 or 2, wherein the heat exchanger further includes: a plurality of fins; and a flow tube that is in contact with the plurality of fins and through which the heat transfer medium flows, and surface positions, on the heat exchanger, to which the additive is fed include a lower end of at least one of the plurality of fins and / or a gap of at least one of the plurality of fins, the gap being formed between the flow tube and a fin collar of the at least one fin, the fin collar being a contact portion where the at least one fin is in contact with the flow tube.

4. The heat exchange system according to any one of claims 1 to 3, further comprising: a fixing member that fixes the feeding member to the heat exchanger; and a drain pan that receives water that falls from the surface, wherein surface positions, on the heat exchanger, to which the additive is fed include a contact position where the heat exchanger is in contact with the fixing member and / or a facing position where the heat exchanger faces the drain pan.

5. The heat exchange system according to any one of claims 1 to 4, wherein the feeding member contains: a plurality of carriers, each of which carries the additive; and a support that supports the plurality of carriers in a dispersed state, such that the additive is releasable from the carriers to outside of the feeding member.

6. The heat exchange system according to claim 5, wherein each of the carriers is a porous granular material.

7. The heat exchange system according to any one of claims 1 to 6, wherein the additive dissolves, disperses, or diffuses in the water adhering to the surface.

8. Applied equipment comprising the heat exchange system according to any one of claims 1 to 7.

9. The applied equipment according to claim 8, wherein the applied equipment is a refrigeration apparatus that refrigerates or freezes an object to be refrigerated or frozen.

10. The applied equipment according to claim 8, wherein the applied equipment is an air conditioner including an outdoor unit, and the heat exchanger and the feeding member are disposed in the outdoor unit.

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