JP2010175131A - Heat exchange device, refrigerating air conditioner and method of manufacturing heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein a heat exchanger of a conventional refrigerating cycle device mainly requires processing of a fin, such as application of hydrophilic nature and change in the fin shape to improve water draining performance. <P>SOLUTION: By providing pores on a fin surface, water draining performance is improved. When condensed droplets are generated on the fin surface, to improve condensation heat transfer, -OH group on the fin surface is controlled so that the fin includes both a hydrophilic portion and a water repellent portion, or to improve heat transfer performance, irregularities are provided on the fin surface so as to increase the surface area. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

This invention is a heat exchanger that is installed in air conditioners, low-temperature equipment, hot-water supply equipment, etc., that exchanges heat with air, and promotes drainage of defrost water by improving drainage of the heat exchanger. It is.

In the conventional refrigeration cycle system, when the surface temperature of the fin used for the heat transfer surface is cooled below the air dew point temperature, water vapor in the air is condensed on the fin surface and water droplets are generated on the surface. In particular, when the fin temperature is 0 ° C. or lower, a frosting phenomenon occurs in which water vapor in the air becomes frost on the fin surface.

As frost formation on the fin surface progresses, the thermal resistance of the fin surface increases. As a result, the amount of heat exchange with air decreases, leading to a reduction in the performance of the apparatus. Furthermore, frost adheres, the gap between the fins is blocked, the air path resistance is increased, and the performance of the apparatus is greatly deteriorated.

In order to avoid such performance degradation, an apparatus using a refrigeration cycle or the like such as a refrigerator periodically performs a defrost (defrost) operation.

Defrost operation includes, for example, a hot gas system that heats the target heat exchanger from the inside by switching the refrigerant flow in the refrigeration cycle, and a heater system that heats from the outside with a heater provided near the heat exchanger. During the defrosting in the defrost operation, the role as an apparatus, for example, the comfort in air conditioning is reduced, and the efficiency of the equipment is also reduced. Therefore, it is necessary to shorten the defrost operation time as much as possible.

However, when the defrost time is easily shortened and the cooling operation of the heat exchanger is restarted with the defrost water remaining on the fins, the remaining defrost water is the starting point, and frost is generated quickly. As a result, the defrost interval is shortened, for example, the defrost water bridges between the fins, and the energy consumption is increased.

For this reason, a heat exchanger with high drainage performance shortens the defrosting operation time and leads to energy saving of the equipment.

With respect to the drainability of this heat exchanger, in the prior art, for example, a hydrophobic part and a hydrophilic paint film are provided on the fin surface, for example, a hydrophilic part is provided on the film to improve water drainage, or The shape of the fins is changed to facilitate drainage as a shape that facilitates water flow (see, for example, Patent Documents 1 and 2). Further, for example, there is an example in which at least a position through which a cooling pipe passes is made hydrophilic with respect to a cooling plate of a refrigerator to make it difficult for water droplets to adhere (see, for example, Patent Document 3).

In addition, in order to obtain a surface having low liquid wettability with respect to droplets colliding with the steam turbine blade, a fine hole is provided on the surface, and the ratio b / a between the median diameter a and the median interval b of the fine hole is 10 at the maximum. In addition, a technique in which the fine hole size is set to a maximum of 10 micrometers is known. (For example, Patent Document 4)

JP-A-1-014596 (pages 3, 4 etc.) JP 2000-193389 A (Claim 1 etc.) Japanese Patent Laying-Open No. 2005-164199 (FIG. 1 etc.) JP 2007-130747 A (Claims 1 and 4 etc.)

In the heat exchanger of the conventional refrigeration cycle equipment, the processing to fins is mainly done by making it hydrophilic with paint or changing the fin shape to improve drainage performance, and it is irrelevant to the improvement of heat transfer performance. There was a problem that it caused a decrease in performance. In addition, in order to obtain wettability for droplets that collide by fine hole processing, it is known to obtain back pressure by the size and distribution of fine holes, but there are conditions for selecting holes that are not related to heat transfer performance. It was difficult and difficult to manufacture and limited to large holes, so it was difficult and practical to apply to refrigeration cycles.

Further, in the cooling plate of the conventional refrigeration cycle apparatus, it has been mainly to improve the hydrophilicity in order to enhance the cleanliness rather than to improve the amount of heat exchange.

In the present invention, fin drainage performance is improved by providing pores on the heat transfer surface of the heat exchanger, and heat transfer performance is improved. Alternatively, by increasing the area having —OH groups on the heat transfer surface, or adjusting the abundance of —OH groups on the heat transfer surface to make the heat transfer surface hydrophilic, improving drainage performance, and Improve heat transfer performance.

The heat exchange device according to the present invention is formed on the heat transfer surface of the heat exchanger provided in the vertical direction for heat exchange between the refrigerant in the heat exchanger that cools the air to be blown and air, and the heat transfer surface. The diameter of the droplet is such that the equilibrium vapor pressure including the surface energy of the droplet adhering to the heat transfer surface is larger than the equilibrium vapor pressure of the macro droplet adhering to the flat surface without the hole by a predetermined value or more. A plurality of pores distributed on the heat transfer surface having the following diameters to promote drainage on the heat transfer surface.

The heat exchange device according to the present invention includes a heat transfer surface of a heat exchanger formed of aluminum and provided in the vertical direction for heat exchange between the refrigerant in the heat exchanger that cools the blown air and the air, And a hydrophilic surface formed by adjusting the abundance of -OH groups in a part of the heat transfer surface during the surface oxidation treatment of the heat transfer surface. Promotes drainage from hot surfaces.

Moreover, the heat exchanger manufacturing method according to the present invention is a step of generating an oxide film having a plurality of fine holes on the surface by anodizing after washing the heat transfer surface of the heat exchanger formed of aluminum, And a step of performing a heat treatment to stabilize the fine holes without sealing after the oxidation treatment, and the heat treatment time is set to a short time for leaving —OH groups on the heat transfer surface.

According to the present invention, drainage of the heat exchanger is improved, drainage of defrost water generated in the heat exchanger can be promoted, and defrosting operation time can be shortened. In particular, energy saving can be reduced by shortening the defrost time by providing this effect in a low-temperature device such as a refrigerator cooler. In order to improve drainage, unevenness is provided on the surface of the heat exchanger to increase the area having —OH groups on the fin surface, thereby improving hydrophilicity. In addition, by adjusting the amount of —OH groups present on the surface of the heat exchanger, it is possible to impart a hydrophilic portion to the surface of the heat exchanger, thereby improving the heat transfer performance. With the above, it leads to energy saving of equipment and devices and is useful for environmental protection.

It is a refrigerant circuit figure of the freezing apparatus which shows Embodiment 1 of this invention. It is detail drawing of the evaporator heat exchanger which shows Embodiment 1 of this invention. It is explanatory drawing at the time of frost formation of the evaporator heat exchanger which shows Embodiment 1 of this invention. It is an operation | movement flowchart at the time of frost formation of the refrigerating cycle which shows Embodiment 1 of this invention. It is structure explanatory drawing of the refrigerator which shows Embodiment 1 of this invention. It is characteristic explanatory drawing of Embodiment 1 of this invention. It is a model explanatory drawing of the heat exchanger with the pore which shows Embodiment 1 of this invention. It is explanatory drawing explaining the content of the anodizing process which shows Embodiment 1 of this invention. It is the schematic of the fin with a slit which shows Embodiment 2 of this invention. It is detail drawing of the evaporator heat exchanger which shows Embodiment 3 of this invention. It is a schematic explanatory drawing of the surface state which shows Embodiment 3 of this invention.

Embodiment 1.
The configuration of the first embodiment of the present invention will be described using a refrigeration apparatus as an example with reference to the drawings. FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus. This refrigeration apparatus is an apparatus that performs vapor compression refrigeration cycle operation. In the figure, a compressor 11, a condenser 12, and a condenser fan 13 are provided, and an expansion means 14, an evaporator 15, and an evaporator heat exchanger fan 16 are provided. The apparatus is filled with a refrigerant. By using the condenser 12 and the evaporator 15, an air conditioner such as an air conditioner or a dehumidifier, a low-temperature device such as a freezer or a refrigerator, a hot water supply device, or the like can be operated with high efficiency.

The refrigerant in the apparatus is compressed by the compressor 11 and flows into the condenser 12 at a high temperature and a high pressure. The refrigerant dissipates heat in the condenser 12 to become a liquid refrigerant, and then expands by the expansion means 14 to become a gas-liquid two-phase refrigerant. In the evaporator 15, the refrigerant absorbs heat from the ambient air and returns to the compressor 11 as a gas. In the case of chlorofluorocarbon refrigerants and HC refrigerants, condensation occurs and gas and liquid refrigerants are present, so the condenser 12 is used to condense the gases into liquids. However, in the case of supercritical pressure refrigerants such as CO2, heat is dissipated. It becomes the heat radiator 12.

FIG. 2 shows details of the evaporator 15 shown in FIG. Here, the fin tube type heat exchanger widely used for the refrigeration apparatus and the air conditioner is shown. The condenser 15 is mainly composed of a plurality of heat exchange fins 21 and a plurality of heat transfer tubes 22. A plurality of fins 21 are laminated at a predetermined interval, and a heat transfer tube 22 is provided so as to penetrate through holes provided in each fin. The liquid refrigerant flowing through the heat transfer tube 22 is vaporized to absorb heat and exchange heat with the external air via the fins 21. As the fin material, an aluminum plate that is easy to process and has good thermal conductivity is often used. In order to efficiently perform the heat exchange process with air, the evaporator 15 is fed with air by an evaporator fan 16 provided in parallel toward the fins 21. Although the parallel plate-like fins will be described here, the same operation and effect can be obtained even with a corrugated fin, for example.

For example, in a refrigerator, the temperature of the air flowing into the evaporator 15 is about −15 ° C., and the evaporation temperature of the liquid refrigerant in the evaporator 15 is about −20 ° C. The fin surface is 0 ° C. or less, and frost formation occurs on the fins 21 due to water vapor flowing in the air. Due to the frost formation, the space between the fins 21 is blocked by the frost layer 31 as shown in FIG. 3, the air volume is reduced, the amount of heat exchange with the air is reduced, and the cooling performance is deteriorated. 3 is a view of the main part of the heat exchanger as seen from an angle, and FIG. FIG. 4 shows an operation process of a general refrigeration cycle apparatus when frost forms on the fin surface.

In order to remove the frost layer 31 generated on the fin, the apparatus performs a defrosting operation. For example, in a refrigerator, a heater is placed around the evaporator 15 and the frost layer 31 is melted by heating the heater. FIG. 5 shows a structure explanatory diagram of the refrigerator. A refrigerant circuit such as a compressor (not shown) is provided on the rear side of the refrigerator compartment of the refrigerator body, and the cool air cooled by passing through a cooler 51 which is an evaporator 15 connected to the refrigerator circuit is blown into the refrigerator body by the blower. In this structure, the air that has been circulated and stored in each of the storage rooms, the freezing room, the refrigeration room, the vegetable room, etc. and cooled to a high temperature is returned to the cooler 15 and cooled.

The melted frost becomes defrosted water, falls through the fins in the direction of gravity, is collected from the cooler 51, which is the evaporator 15, to the drain pan installed in the lower part through the drainage channel 52, is evaporated to the outside, and flows out.

For example, a refrigerator has a drainage structure having a drainage channel 52 in the direction of gravity as shown in FIG. 5, and a drain pan 53 is installed below the cooler 51.

At this time, when the operation of the refrigeration apparatus is started again as shown in FIG. 4 while leaving the defrost water on the fins 21, frost is generated starting from the defrost water remaining on the fins 21. Therefore, it is important to reliably remove the defrost water from the surface of the fin 21. That is, in the case of a refrigerator, for example, as shown in FIG. 4, when the refrigerator is turned on or the compressor is operated, the cooling operation starts (S01), and moisture generated from the vegetable compartment of the refrigerator is cooled by the cooler. If it touches 51, it will become frost and will adhere to a heat-transfer surface (S02). When the frost is formed on the cooler, the original cooling performance of hindering the circulation of cold air or cooling the refrigerator by lowering the heat transfer rate is lowered (S03). If this is detected by temperature or the like, defrosting (S04) is performed by heating the heater or the like.

In the following, in order to shorten the defrosting time shown in FIG. 4, a technique for improving the drainability of the heat exchanger by providing pores on the fin surface will be described. First, the influence of the surface energy of the droplet is considered.

The equilibrium vapor pressure p of the water droplet when the surface energy is added to the water droplet of radius r is given by the following equation.

Where k is the Boltzmann constant, T is the temperature, p _e is the equilibrium vapor pressure of a macroscopic water droplet with a flat plane, v is the volume of one molecule, and γ is the surface energy density.

Figure 6 is a characteristic diagram, the y is a view showing a p / p _e when the T = 0 [℃] as a function of the radius r of the water droplets. However, γ = 76 [erg / cm ² ] and v = 3 * 10 ⁻²³ [cm ³ ] (physical property values of water at 0 ° C.) were used. Note also water droplet radius r dependency of p / p _e shown in FIG. 6 changes the T (e.g. T = -10,10 even [° C.]), the value does not change significantly.

FIG. 6B is a diagram for explaining the equilibrium vapor pressure of water droplets at the water droplet outer peripheral portion 73 when the water droplet diameter is large. As shown in (a) of FIG. 6, p / p _e is asymptotic to 1 as the radius r increases. FIG. 6 shows only up to r = 1000 [nm], but p / _pe is almost 1 at r> 1000 [nm]. This means that a water droplet with a radius r> 1000 [nm] attached to a surface with a fine hole is equal to the equilibrium vapor pressure of a macro water droplet attached to a flat surface without a fine hole, as shown in FIG. Means.

On the other hand, FIG. 6C is a diagram for explaining the equilibrium vapor pressure of water droplets at the water droplet outer peripheral portion 73 when the water droplet diameter is small. When the water droplet radius is r <1000 nm, p / _pe is 1 or more. Since the p> p _e, the equilibrium vapor pressure of the water droplets is greater than the equilibrium vapor pressure of macroscopic droplets given in the plane. This is because the ratio of the surface area to the volume increases as the droplets become smaller, and the surface energy is disadvantageous, so that water molecules in the droplets become unstable.

As shown in the schematic diagram 6 above, for example, when water droplets exist in air having an air temperature of 2 ° C. and a relative humidity of 80%, water vapor flows from the air at the surface of the water droplets at p _e = 564 Pa. Yes. On the other hand when the water droplets are present stable at radius r _0, the water is evaporated at p _e from water droplets, inflow and outflow are balanced.

On the other hand due to the influence of the surface energy in the diameter is small water droplets, water vapor or moisture flowing in p _e flows out from the water droplets, water droplets diameter r ₀ is increasingly smaller.

That is, in order to produce a small radius of the droplet stability, it is necessary to give the equilibrium vapor pressure p _e or more vapor pressure obtained when the liquid droplet is a macro water drops with plane.

FIG. 7 schematically shows the situation when there are many pores 72 having a diameter of 100 nm on the surface. Water droplet size that can be present in the pores of diameters of 100 nm is below 100 nm, this time, from FIG. 6 p> and 1.01 p _e.

When such pores 72 Joshimosui 71 at the top came, pore 72 top Joshimosui 71 (macro water drop) is generated stably, its equilibrium vapor pressure is p _e. However, to droplets in the pores 72 are generated requires 1.01 times more vapor pressure p _e. That is, since water droplets cannot exist stably in the pores 72, the defrost water 71 cannot enter the pores 72 and is filled with an air layer.

As a result, when a large number of pores 72 having an air layer are present on the surface as shown in FIG. 7, the defrosted water outer peripheral portion 73 comes into contact with the pores 72 having the air layer inside.

When the outer peripheral portion 73 of the defrost water 71 and the pore 72 having the air layer are in contact with each other, since the surface tension of water is large, the defrost water 71 cannot stay on the pore 72 and from the air layer. Try to leave. Due to this effect, as long as the defrosted water outer peripheral portion 73 is in contact with the pore 71 having an air layer, it does not stay on the pore 71 but flows down from the surface of the fin 21 in the direction of gravity.

In order to remove the defrosted water 71 more efficiently, it is important to keep the pores 72 filled with the air layer in the direction of gravity to the lowest part of the fins 21 as shown in FIG. 7A is an explanatory diagram in which the defrost water 71 is attached to the surface of the fin 21, FIG. 7B is an explanatory diagram in which the narrow hole 72 is viewed from the side, and FIG. 7C is a diagram in which the defrost water flows downward by gravity. It is a figure explaining the easy structure.

In order to shorten the exclusion time, a heat exchanger having short fins in the gravity direction and long in the vertical direction is effective rather than a heat exchanger having long fins in the gravity direction, as shown in FIG. . An example of such a heat exchanger is a cooler used in a refrigerator. Therefore, for example, in a refrigerator or the like, it is preferable to provide fins substantially parallel to the direction of gravity as a cooler and to make a heat exchanger whose lateral width is larger than the height direction width. Furthermore, since the pores exist up to the lower end of the heat transfer surface, the defrost water flowing due to gravity is smoothly drained from the heat transfer surface without stopping due to frost.

From the above, by providing a large number of small-diameter pores on the fin surface where the disadvantage of surface energy is significant, the discharge of defrost water can be promoted, and the draining performance of the fin can be improved. As a result, the defrost time can be shortened and energy saving of the apparatus can be achieved. Since such pores require a larger vapor pressure as the diameter is smaller as shown in FIG. 6, an air layer can be obtained in the pores 72 more stably.

Although the number of pores on the fin surface is not limited in the above, it can be said that the effect of draining is higher as the number of pores is larger as described above. There is no problem even if the pore penetrates the fin, but considering the strength of the fin, it can be said that the effect is sufficiently obtained if the pore is sealed at one end from the through hole and the depth is several nm or more.

For example, an anodic oxidation method can be cited as a method for forming nano-order holes on the surface of the heat exchanger. In the anodic oxidation method, direct current electrolysis is performed in an electrolyte solution using a metal to be treated as an anode and an insoluble electrode as a cathode. An explanatory diagram relating to the anodizing treatment is shown in FIG. FIG. 8A is a schematic diagram of an anodizing apparatus, and FIG. 8B shows a general anodizing process. In the apparatus, an object to be processed as an anode 82, for example, an aluminum plate such as a fin plate, is installed between cathodes 81 in a liquid tank filled with an electrolytic solution 83, and a voltage is supplied from a voltage variable DC power source such as a chopper power source. It is good to control so that it may become a preset electric current, and to energize for the preset time. Prior to the anodizing process (S16), first, as a surface cleaning of the object to be processed such as a fin plate, generally, degreasing (S10), washing with water (S11), and a natural oxide film formed on the surface of the fin plate are removed. Alkali etching (S12), washing with water (S13), desmutting treatment (S14) for removing reactants as impurities generated on the surface by wet etching, and washing with water (S15) are performed. Thereafter, the object to be treated of the present invention is immersed in, for example, a 0.5M-H 2 SO 4 electrolytic solution controlled at 20 ° C., anodized by constant current control for about 30 minutes, and then rinsed with ion-exchanged water ( The blower is drained with S17), immediately put into an oven heated to 150 ° C., and subjected to a heat treatment (S18) for 60 minutes, followed by slow cooling. Thereby, the fine hole formed in the surface can be stabilized. If heat treatment such as the example described above is not performed, the narrow hole will collapse in a short period of time, and in the case of alumite treatment, heat treatment such as boiling water or steam that closes the narrow hole is performed. The heat treatment is for maintaining a fine hole that is stable for a long period of use.

8A and 8B, when the cathode 81 and the anode 82 are energized, the metal surface of the anode is oxidized, and a part of the metal is ionized and dissolved in the electrolyte solution 83. In particular, aluminum, niobium, tantalum and the like have an oxide film by an anodic oxidation method. Since this oxide film has poor electrical conductivity, a metal oxide is formed on the substrate as the anodizing treatment proceeds, and a regularly grown pore structure is formed. The depth of the pores is determined by the time during which the voltage is applied, but it can be said that the degree of not penetrating is good in terms of strength as described above. In the apparatus configuration shown in FIG. 8A, the fins are schematically described. However, the entire heat exchanger may be anodized. For example, the central axis of the heat exchanger is provided in the direction that the wind passes through the fins of the heat exchanger, and carbon plates on a flat plate are installed as a plurality of negative electrodes on both sides of the position where the air is blocked with respect to the center line of the central axis. Anodizing is performed. The narrow hole of the present invention formed in the aluminum part of the entire outer periphery of the fin and heat exchanger prevents water from forming mist and frosting by touching the evaporator heat exchanger cooled to 0 ° C. or less. In order to immediately drop the adhered water droplets by gravity, the fin drainage performance is improved by providing pores on the fin surface or the like. For this reason, it is only necessary to provide a fine hole with a diameter of 100 nm or less. In the anodizing treatment, if a long time is taken, the hole collapses and the diameter becomes large. Therefore, by setting the time of this treatment and limiting the time, the diameter of 100 nm or less The narrow hole can be easily formed. Moreover, even if the cathode position is set so as to make fine holes as evenly as possible in the entire heat exchanger as much as possible, due to structural problems such as laminated fins, even if the variation occurs and is 100 nm or less, it is about 10 nm or more In this way, there is a possibility that the hole diameters vary and are generated, and fine holes distributed at a pitch several or several tens of times larger than the hole diameter may be obtained, but the fine holes can be easily formed without a special jig. The pores of the present invention can be drained if there is an air layer in the hole and the distribution of holes is such that water droplets are applied to a plurality of holes. In particular, the holes can be deepened or the diameter of the holes can be made smaller. This is easy to manufacture because the anodization conditions can be set by simple trials.

In addition, since the oxide film has poor thermal conductivity, it is not always good to make a deep hole in order to deteriorate the heat exchange between the surface and air. However, the above-described effect does not change even for a hole that penetrates essentially. For heat exchangers with extremely thin fins smaller than 1 mm, a through hole may be made. In addition, since the holes in the fins are nano-sized, the holes will not be filled with dust or dust over time.

Coolers such as refrigerators are all made of aluminum, including heat transfer tubes. Therefore, when anodizing, the entire heat exchanger is anodized so that nano-sized fine particles can be found all over the surface of the heat exchanger. A hole can be provided, and the drainage performance of the entire heat exchanger is expected to be improved. A part that is not intentionally oxidized, such as the inside of the heat transfer tube 22, may be masked and anodized.

Embodiment 2.
The configuration of the second embodiment of the present invention will be described below. As described in the first embodiment, the improvement of fin drainage improves the performance of the heat exchanger such as heat transfer and blockage between fins. However, the improvement of drainage can be obtained by making the surface hydrophilic. Generally known. The configuration and operation described in FIGS. 1 to 7 in the first embodiment are the same as those in the second embodiment.

The hydrophilicity of the metal surface is obtained by the hydrophilic group on the surface. Specific examples of the hydrophilic group include —OH group and —O group. In particular, the —OH group has high hydrophilicity, and when the —OH group is present on the surface, the water droplets on the surface improve the wettability. Therefore, the —OH group is widely used for the purpose of reducing the contact angle of the water droplets. Further, as the number of —OH groups on the surface increases, the hydrophilicity of the surface is further improved.

As a method for oxidizing the surface of aluminum used in an ordinary evaporator to obtain —OH groups, there is a chemical conversion treatment, for example, a boehmite treatment or an anodization treatment such as an alumite treatment. By these oxidation treatments, the surface of the aluminum plate becomes —OH groups, and even if heat treatment is applied to become —O groups, the hydrophilicity is maintained.

Although the alumite treatment is described in the first embodiment, the boehmite treatment is a chemical treatment in which aluminum is treated in high-temperature water or pressurized steam to generate —OH groups on the surface, and an oxide film is formed on the aluminum surface.

In order to add more -OH groups to the surface in both treatments, it is effective to increase the surface area by the unevenness provided on the surface of the fin plate while maintaining the vertical and horizontal dimensions of the fin limited by the size of the heat exchanger It is. Further, by utilizing the holes provided in the fins or the like, the area having —OH groups on the fin surface is increased, the hydrophilicity of the fin surface or the like is further improved, and the drainage property of the fins or the like is enhanced. The irregularities and holes described here may be various such as fine hole machining by anodizing, machining using a jig, drilling by laser, deformation processing by press, etc. The deeper the heat exchanger, the more effective the surface area of the heat transfer surface can be touched even if the heat exchanger size remains the same.

An example of a method for increasing the surface area of the fin is an anodizing method. As described in Embodiment Mode 1, when aluminum is anodized, a large number of fine or large-sized holes can be distributed and provided. The —OH group is also generated on the surface of the generated hole by the anodizing treatment, and the amount of —OH group on the surface can be increased.

If the surface oxide film is stabilized by heat treatment or the like for this —OH group, a heat exchanger with improved hydrophilicity can be produced, and the drainage of the heat exchanger can be improved.

As a method of using the hydrophilic treatment method, as shown in FIG. 9, it is also effective for a heat exchanger having a slit 91 in the fin 92 so as to efficiently exchange heat with air, for example. The slit fin 92 has a slit 91 on the fin 92 in order to actively exchange heat with air. At this time, the relationship between how the slit stands, the direction of air flow, and the direction of gravity are as shown in FIGS.

Although the slit 91 produces the effect described above, the amount of condensed droplets is large because the amount of heat exchange is large in the slit 91 portion. For this reason, in the slit fin, condensed water droplets often stagnate in the slit portion and block the air path.

In order to continuously obtain the effect of the slit 91, as shown in FIG. 9C, by making a hole 93 in the slit 91 portion to increase the surface area, the hydrophilicity is increased and the drainage is expected to be improved. Sometimes it works effectively. As shown in FIG. 8, after making a fine hole by anodizing treatment in the entire fin, the slit may be formed by press working, or the fine hole may be formed in the slit portion by masking except for the position around the slit. .

Further, by making the hole diameter to be sufficiently smaller than the diameter of dust, dust or the like normally assumed indoors or outdoors, the hole is not blocked and the effect can be maintained over time. A heat exchanger with good drainage can be obtained by processing large holes or increasing the hydrophilic surface area by unevenness.

The type of the heat exchanger of the present invention is not limited to the above description, and can be applied to, for example, a corrugated fin of an air conditioner used in an automobile. Further, the present invention can be applied to many devices such as a refrigeration warehouse using a refrigeration cycle using the evaporator of the present invention, a hot water supply device, or an air conditioner such as a dehumidifier.

Embodiment 3.
The configuration of the third embodiment of the present invention will be described with reference to the drawings. FIG. 10 shows a part of the fins 21 and the heat transfer tubes 22 of the evaporator 15 of FIGS. 1 and 2 shown in the first embodiment.

When the fin 21 is cooled below the air dew point temperature, water vapor in the air condenses on the fin surface to form water droplets. At this time, if the fin surface is hydrophilic, the contact angle becomes small, so that film condensation occurs, and a water film 101 is formed on the fin 21 surface.

On the other hand, on a metal surface that is not hydrophilic and is not water repellent or hydrophilic, the contact angle is large, so droplet condensation occurs on the surface, and water droplets 102 are generated on the surface of the fin 21.

Generally, condensation heat transfer is larger in the case of droplet condensation than in film condensation (about 10 times), and when the condensation is realized by a heat exchanger, an increase in the amount of heat exchange is expected. For example, when the evaporator 15 is operated as a dehumidifier, the amount of heat exchange due to condensation becomes dominant, so that it can be said that droplet condensation is important for efficient operation.

However, this effect also depends on the spacing between the fins. For heat exchangers with extremely narrow fin pitches, the presence of droplets of condensed water droplets on the surface results in air path resistance between the fins, which increases the input to the evaporator fan 16 and causes fan noise problems. appear.

For this reason, the amount of heat exchange is increased by encouraging drainage in addition to droplet condensation. That is, a heat exchanger with high condensation heat transfer can be realized by giving an optimum hydrophilicity to the fins. If it is difficult to capture the degree of hydrophilicity, perform a heat treatment that adds hot water to the fins during the final heat treatment so that the hydrophilic portion and the water-repellent portion are mixed, and limit the range of this heat treatment. Ho Li River is possible.

For example, in a refrigerator cooler, the fin pitch is different for each row, so it can be expected that there is an optimal hydrophilicity at each position.

A method for adjusting the hydrophilicity of the fin surface will be described below.

FIG. 11 schematically shows the molecular state of the hydrophilic aluminum fin surface. As described in the second embodiment, when an —OH group is present on the surface, the surface becomes hydrophilic, and water droplets on the surface improve wettability. When sufficient heat treatment is applied, the —OH group changes to the —O group, but this —O group is also hydrophilic, although not as much as the —OH group.

As a method for imparting —OH groups to the surface, for example, boehmite treatment achieves extremely high hydrophilicity by generating a stable hydrated oxide on the surface.

In the anodic oxidation treatment described in the first embodiment, as shown in FIG. 10, the surface hydroxyl group-OH group on the surface of the aluminum fin is heat-treated to remove the —OH group as water H 2 O, and the surface has the —O group. It has been stabilized.

In FIG. 11, —OH groups on the entire surface are converted to —O groups by heat treatment, but an appropriate amount of —OH groups can be left on the surface by adjusting the heat treatment time. For example, by shortening the heat treatment time, a part of the surface —OH groups can be converted into —O groups, and part of the hydrophilicity of the fin can be maintained.

Further, FIG. 10 shows a state where a hydrophilic water film and water-repellent water droplets are mixed, but these can be easily manufactured by masking at the time of oxidation treatment. There is also a method of adjusting the heat treatment time (adjusting the -OH group) on the upwind side and downwind side of this fin. Or you may classify by the size of fin pitch. Generally, the heat transfer rate is high on the leeward side, so the decrease in the heat exchange amount is small even if film-like condensation occurs, but the heat exchange amount of the fins can be further increased by using droplet condensation on the leeward side. It becomes possible. As a result, drainage can be improved and heat transfer performance can be improved.

Such a method for adjusting the —OH group makes it possible to produce a heat exchanger having the desired hydrophilicity, and to impart a distribution of hydrophilicity on the fin surface, leading to improved performance of the heat exchanger. As a method of adjusting this -OH group to a part of -O group, the heat treatment time after anodizing treatment is adjusted, or the heat treatment temperature condition or the heat treatment environment of only a part of the object is changed, that is, the object. For some heat treatment measures such as anodizing, such as masking a part of the product, separating the hot water from the non-heated, etc., depending on the shape and size of the object and the structure of the device to be applied, A structure in which a portion and a water-repellent portion are mixed and provided.

The heat exchanger according to the present invention is provided with pores having a diameter equal to or less than the droplet diameter on which the surface energy affects the heat transfer surface that exchanges heat with the air in the heat exchanger in the apparatus that performs the refrigeration cycle. By filling the hole with an air layer, facilitating drainage of defrost water on the fin surface, and providing a narrow hole in the entire heat exchanger, it is possible to touch the cooler when using this heat exchanger as a cooler. A device that can easily drain the condensed water droplets and improve the heat exchange performance is obtained.

The heat exchanger of the present invention adjusts the hydrophilicity of this surface by adjusting the number of —OH groups on the surface that exchanges heat with the air in the heat exchanger in the apparatus that performs the refrigeration cycle. Give to the surface. Also, by adjusting the -OH group on the leeward side or on the upwind side of the air flow, water droplets condensed by touching the cooler when this heat exchanger is used in a cooler can be easily drained, and heat A device that improves the exchange performance is obtained.

The heat exchanger of the present invention is provided with many holes on the surface of the heat exchanger in order to improve hydrophilicity on the surface that exchanges heat with the air in the heat exchanger in the apparatus that performs the refrigeration cycle. Increase the surface area of the heat exchanger and increase the —OH groups present on the heat exchanger surface. Moreover, the apparatus which improves a heat exchange performance is provided by providing the slit fin with a slit in a heat-transfer fin, and giving many holes for the hydrophilicity improvement in the said slit part vicinity.

If this invention is utilized, the draining property of the heat exchanger which heat-exchanges with air will improve, and it will lead to the drainage improvement of the defrost water produced on the surface. In particular, in the refrigeration cycle system, energy can be saved by shortening the defrosting time. In addition, by setting the heat exchanger surface to a desired hydrophilicity, a heat exchanger with high condensation heat transfer can be realized, and the heat exchange amount of the equipment can be improved. Furthermore, increasing the surface area of the heat exchanger surface further improves hydrophilicity, leading to energy saving for refrigeration equipment such as commercial freezers and household refrigerators, and refrigeration and air conditioning equipment such as air conditioners and dehumidifiers.

A refrigeration cycle apparatus having a heat exchanger according to the present invention includes a refrigerant cycle in which a compressor, a condenser, an expansion unit, and an evaporator are connected to circulate a refrigerant, a blowing unit that blows air to the evaporator, and an evaporator Provided with pores on the surface of the heat exchanger that makes up the pores, the pore size should be less than the droplet size that the surface energy affects, fill the pores with an air layer, and promote drainage of defrost water on the fin surface As a result, it is possible to improve the drainage performance and to obtain a device with good heat transfer efficiency.

Further, the refrigeration cycle apparatus having the heat exchanger according to the present invention includes a refrigerant cycle in which a compressor, a condenser, an expansion unit, and an evaporator are connected to circulate the refrigerant, a blowing unit that blows air to the evaporator, and evaporation Since the surface of the heat exchanger is increased by providing holes in the surface of the heat exchanger in order to improve the hydrophilicity of the surface of the heat exchanger constituting the heat exchanger, a device with good performance can be obtained.

Further, the refrigeration cycle apparatus having the heat exchanger according to the present invention includes a refrigerant cycle in which a compressor, a condenser, an expansion unit, and an evaporator are connected to circulate the refrigerant, a blowing unit that blows air to the evaporator, and evaporation By adjusting the number of —OH groups on the surface of the heat exchanger constituting the vessel, hydrophilicity can be imparted to the surface of the heat exchanger, and drainage performance can be improved.

This invention aims at improving the drainage performance of fins by providing pores on the fin surface with respect to the evaporator heat exchanger fins cooled to 0 ° C. or lower. Further, by utilizing the holes provided in the fin, the area having the —OH group on the fin surface is increased, the hydrophilicity of the fin surface is further improved, and the drainage property of the fin is enhanced. In addition, when the evaporator heat exchanger fins are cooled below the air dew point temperature, condensed water droplets are generated on the fin surface.In order to improve condensation heat transfer, the amount of --OH groups present on the fin surface is controlled. By optimizing the hydrophilic state of the fin surface, the fin can be made to have an arbitrary hydrophilicity to improve the heat transfer of condensation.

According to the present invention, the drainability of the heat exchanger is improved, drainage of defrost water generated in the heat exchanger can be promoted, and defrost time can be shortened. In particular, energy saving can be achieved by shortening the defrost time by providing this effect in a low-temperature device such as a refrigerator cooler. In order to further improve drainage, a hole is provided on the surface of the heat exchanger to increase the area having —OH groups on the fin surface, thereby increasing hydrophilicity. In addition, by adjusting the -OH group on the surface of the heat exchanger, the desired hydrophilicity can be imparted to the surface of the heat exchanger, and condensation heat transfer can be improved. The above effects lead to energy saving of equipment.

DESCRIPTION OF SYMBOLS 11 Compressor, 12 Condenser, 13 Condenser fan, 14 Expansion means, 15 Evaporator, 16 Evaporator fan, 21 Heat transfer fin, 22 Heat transfer pipe, 31 Frost layer, 51 Cooler, 52 Drain channel, 53 Drain pan, 71 defrosted water, 72 pores filled with air, 73 outer periphery of defrosted water, 81 cathode, 82 anode, 83 electrolytic solution, 91 slit, 92 slit fin, 93 hole, 101 water film, 102 water droplets.

Claims (16)

There are a heat transfer surface of the heat exchanger provided in the vertical direction for heat exchange between the refrigerant in the heat exchanger for cooling the air to be blown and the air, and a narrow hole formed in the heat transfer surface. And the equilibrium vapor pressure including the surface energy of the droplets adhering to the heat transfer surface has a diameter equal to or smaller than a droplet diameter that is larger than the equilibrium vapor pressure of the droplets adhering to a flat surface without a fine hole by a predetermined value or more. A heat exchange device comprising: a plurality of pores distributed on a hot surface, and promoting drainage on the heat transfer surface. The predetermined value for making the equilibrium vapor pressure including the surface energy of the droplets adhering to the heat transfer surface larger than the equilibrium vapor pressure of the macro droplets adhering to a flat surface without a fine hole is 1.03 times. The heat exchange device according to claim 1. The equilibrium vapor pressure including the surface energy of the droplets adhering to the heat transfer surface is larger than the equilibrium vapor pressure of the macro droplets adhering to the flat surface without fine holes by a predetermined value or more. The heat exchange device according to claim 1, wherein the heat exchange device has a diameter. The heat exchange device according to claim 1, wherein the plurality of narrow holes formed on the upper and lower sides of the heat transfer surface are formed to at least the vicinity of the lower end of the heat transfer surface. The heat transfer surface of the heat exchanger formed of aluminum provided in the vertical direction for heat exchange between the refrigerant in the heat exchanger that cools the air to be blown and the air, and surface oxidation of the heat transfer surface A hydrophilic surface formed by adjusting the abundance of -OH groups in a part of the heat transfer surface during the treatment, and mixing the hydrophilic surface with the heat transfer surface from the heat transfer surface A heat exchange device that promotes drainage of water. The hydrophilic surface formed by adjusting the abundance of —OH groups in a part of the heat transfer surface is provided on the leeward side of the air flowing through the heat exchanger. Heat exchange device. Provided in a distributed manner on the heat transfer surface of the heat exchanger provided in the vertical direction for exchanging heat between the refrigerant in the heat exchanger that cools the air to be blown and the air. A heat exchange device comprising: a plurality of irregularities, wherein the irregularities increase a surface area that can come into contact with the air having —OH groups of the heat exchanger. The hydrophilic surface formed on the heat transfer surface is characterized in that after the heat transfer surface oxidation treatment, a heat treatment condition of a part of the heat transfer surface is changed to adjust the abundance of -OH groups. The heat exchange apparatus according to 5 or 7. The heat exchange apparatus according to claim 1, wherein the fin forming the heat transfer surface has a plurality of slits on a surface thereof and a plurality of holes in the vicinity of the slits. The heat exchanging apparatus according to claim 1 or 7, wherein the plurality of fine holes or irregularities formed above and below the heat transfer surface are formed on the windward side of the air flowing through the heat transfer surface. . The heat exchange device according to claim 1, wherein the fins forming the heat transfer surface have a vertical width shorter than a horizontal width. The heat exchange apparatus according to claim 1, wherein the narrow hole or the unevenness is formed in the entire heat exchanger. A refrigeration cycle in which the heat exchange device according to any one of claims 1 to 12 is connected as an evaporator, and frost adhering to a heat transfer surface of the heat exchanger that operates the refrigeration cycle and exchanges heat with air is intermittently removed. A refrigeration / air-conditioning apparatus comprising: a defrosting device that is heated and removed, and drainage collecting means that collects wastewater removed by the defrosting device at a lower portion of the heat exchanger. After cleaning the heat transfer surface of the heat exchanger made of aluminum, anodizing is performed to form an oxide film having a plurality of fine holes on the surface, and after the oxidation treatment, the fine holes are sealed. And a step of performing heat treatment that stabilizes without forming holes, and the heat treatment time is a short time for leaving -OH groups on the heat transfer surface. The fin or heat exchanger as a heat transfer surface is used as an anode, and a part of the fin or the entire heat exchanger is masked when manufactured by anodizing treatment in an electrolytic solution. The heat exchanger manufacturing method according to claim 14. After cleaning the heat transfer surface of the heat exchanger formed of aluminum, performing a chemical conversion treatment to generate an oxide film on the surface, and performing a heat treatment to stabilize the heat transfer surface after cleaning after the oxidation treatment; The heat treatment time is a short time for leaving -OH groups on the heat transfer surface.

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