US20200025464A1

US20200025464A1 - Fin-type heat exchanger

Info

Publication number: US20200025464A1
Application number: US16/484,111
Authority: US
Inventors: Wenhsin CHIANG
Original assignee: Nine-Tops Materials Co Ltd; Nine Tors Materials Co Ltd
Current assignee: Nine-Tops Materials Co Ltd; Nine Tors Materials Co Ltd
Priority date: 2017-02-07
Filing date: 2017-02-07
Publication date: 2020-01-23
Also published as: WO2018145253A1; CN109041577A; CN109041577B

Abstract

A fin-type heat exchanger is provided, including fins and refrigerant pipes. Air is heat-exchanged in an air passage between the refrigerant pipes and the fins by introducing a refrigerant into the refrigerant pipes. A surface of each of the fins includes a heat dissipation layer, which includes first heat dissipating powders with a first particle size and second heat dissipating powders with a second particle size. Material of the heat dissipation layer includes nano-graphite, carbon nano-tube, boron nitride, or nano-diamond. By forming the heat dissipation layer, a heat exchange area of the fins is increased, heat radiation and conductivity of the fins are enhanced, the fins are controlled to be hydrophobic or hydrophilic, and a surface friction coefficient can be reduced to improve efficiency of thermal convection, so the heat dissipation layer exhibits excellent ultraviolet and corrosion resistance.

Description

FIELD OF DISCLOSURE

The present disclosure relates to a fin-type heat exchanger, and more particularly to a fin-type heat exchanger for use in a refrigeration or air conditioning system.

BACKGROUND

In a refrigeration or air conditioning system, in order to improve a heat dissipation performance of units, a fin-type heat exchanger having a large heat exchange area is usually used. In order to enhance a heat exchange performance and lifespan of the fin-type heat exchanger, various improvement methods have been proposed as follow.
First, a heat dissipation fin is made of aluminum, and a blue film is formed on the heat dissipation fin by an epoxy-coated treatment. An outer layer of the blue film is coated with an acrylic resin having rust prevention performance to effectively prevent acid rain and salt erosion. Moreover, a hydrophilic film is coated on its outermost layer. Therefore, water droplets can be evenly distributed on the heat dissipation fin, which can avoid rust and corrosion, thereby effectively extending a lifespan and resisting a hot, humid, and high salt environment. In general, aluminum combines with oxygen in air to form an aluminum oxide. This oxide layer contributes to corrosion protection. However, if there are other corrosive substances in the environment, such as chloride ions, the oxide layer will be destroyed and corroded continually. An isolating film composed of a epoxy resin can be formed on the heat dissipation fin by epoxy-coated treatment. In theory, chlorine ions can be prevented from contacting the aluminum fin to prevent corrosion. However, in practice, since the epoxy-coated treatment is a pre-treatment, a coating operation must be completed in a factory that supplies aluminum. When the epoxy-coated treated aluminum is sent to a heat exchanger manufacturer, a machined surface forms many cuts and breaks. These cuts and breaks cause corrosion factors to enter the heat dissipation fin, causing the heat dissipation fin to corrode. Also, the oxide layer on the surface of the aluminum fin does not prevent corrosion from continuing, especially in a humid environment. Thus, once corrosion occurs, it will continue. Furthermore, respective aluminum alloys have different corrosion resistances, and corrosion results vary depending on crystal phase. In a case of a commonly used 1100 aluminum alloy, local deep corrosion is easily exhibited in a salt spray test. Moreover, when tested in an 8006 aluminum alloy, it exhibited a uniform shallow corrosion. Hence, in terms of structural damage, the 1100 aluminum alloy will be more serious. On the other hand, the isolating film composed of the epoxy resin exhibits poor thermal conductivity, and although it has considerable protective ability, it does not have an ability to resist ultraviolet (UV) degradation.
Second, by increasing a diameter and loop of the units or improving an angle and number of threads of an internal thread, a heat dissipation area of the fin-type heat exchanger is increased and the heat dissipation performance is improved. However, this method has disadvantages of large size, heavy weight, and high manufacturing cost.
Accordingly, it is necessary to provide a fin-type heat exchanger to solve the technical problem in the prior art.

SUMMARY OF DISCLOSURE

In order to solve technical problems mentioned above, an object of the present disclosure is to provide a fin-type heat exchanger for use in a refrigeration or air conditioning system. A heat dissipation layer including nanomaterials is formed on a fin of a heat exchanger. Heat dissipating powders of different particle sizes are set to an appropriate ratio, and an adhesive is added. Therefore, a heat exchange area of the fin increases, and heat radiation and conduction of the fin are enhanced. The fin is controlled to be hydrophobic or hydrophilic. Also, a surface friction coefficient is decreased, so as to increase efficiency of thermal convection, such that the heat dissipation layer exhibits excellent UV and corrosion resistance.
In order to achieve the objects described above, the present disclosure provides a fin-type heat exchanger, including: a plurality of fins and a plurality of refrigerant pipes transversely passed through the plurality of fins and disposed between the plurality of fins. Air is heat-exchanged in an air passage between the plurality of refrigerant pipes and the plurality of fins by introducing a refrigerant into the plurality of refrigerant pipes. A surface of each of the fins includes a heat dissipation layer, and the heat dissipation layer includes a plurality of first heat dissipating powders with a first particle size and a plurality of second heat dissipating powders with a second particle size. Material of the heat dissipation layer includes nano-graphite, carbon nano-tube, boron nitride, or nano-diamond.
In one preferable embodiment of the present disclosure, material of each of the first heat dissipating powders is selected from the group consisting of the nano-graphite, the carbon nano-tube, titanium dioxide, the boron nitride, carbon black, carbon fiber, metal powder, silicon carbide, aluminum oxide, aluminum nitride, aluminum oxide, silicon dioxide, and the nano-diamond.
In one preferable embodiment of the present disclosure, material of each of the second heat dissipating powders is selected from the group consisting of the nano-graphite, the carbon nano-tube, the boron nitride, carbon black, carbon fiber, metal powder, silicon carbide, aluminum nitride, and the nano-diamond.
In one preferable embodiment of the present disclosure, the first particle size of each of the first heat dissipating powders ranges between 300 nanometers and 500 nanometers.
In one preferable embodiment of the present disclosure, the second particle size of each of the second heat dissipating powders ranges between 25 nanometers and 35 nanometers.
In one preferable embodiment of the present disclosure, the first heat dissipating powders present more than 0% to 35% of the heat dissipation layer content.
In one preferable embodiment of the present disclosure, the second heat dissipating powders present in a range from 5% to 40% of the heat dissipation layer content.
In one preferable embodiment of the present disclosure, the heat dissipation layer further includes an adhesive covering the first heat dissipating powders and the second heat dissipating powders, and the adhesive is configured to reduce a surface friction coefficient of the heat dissipation layer. Material of the adhesive is selected from the group consisting of polyacrylate, a polyvinyl alcohol resin, and siloxane.
In one preferable embodiment of the present disclosure, in response to the fin-type heat exchanger is disposed in an indoor unit of a refrigeration system, a ratio of the first particle size to the second particle size ranges between 10:1 and 30:1, such that the heat dissipation layer is hydrophobic.
In one preferable embodiment of the present disclosure, in response to the fin-type heat exchanger is disposed in an outdoor unit of a refrigeration system, a ratio of the first particle size to the second particle size is greater than 500:1, such that the heat dissipation layer is hydrophilic.
In comparison to the prior art, the present disclosure discloses that the heat dissipation layer including nano-materials is formed on fins of the heat exchanger. The heat dissipation layer includes heat dissipating powders of different particle sizes, so that a heat exchange area of the fins is increased and heat radiation and conduction of the fins are enhanced. Also, the heat dissipating powders of different particle sizes are set to an appropriate ratio for controlling the fin to be hydrophobic or hydrophilic, such that the fin is formed to have a high moisture content or self-cleaning ability. Furthermore, by adding the adhesive to the heat dissipation layer, the surface friction coefficient can be reduced to improve efficiency of thermal convection, such that the heat dissipation layer exhibits excellent UV and corrosion resistance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a refrigeration system according to a preferred embodiment of the present disclosure.

FIG. 2 is a pressure-enthalpy diagram showing relationship between pressure and enthalpy of a refrigeration cycle in an ideal environment.

FIG. 3 is pressure-enthalpy diagrams showing relationship between pressure and enthalpy of the refrigeration cycle in the ideal environment and in an actual environment, respectively.

FIG. 4 is a partial schematic diagram of a fin-type heat exchanger according to the preferred embodiment of the present disclosure.

FIG. 5 shows a partial enlarged view of a fin of FIG. 4.

DETAILED DESCRIPTION

The structure and the technical means adopted by the present disclosure to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings.
Please refer to FIG. 1, which is a schematic diagram of a refrigeration system according to a preferred embodiment of the present disclosure. The refrigeration system includes four main units, which are a compressor, a condenser, a refrigerant controller, and an evaporator. According to a refrigeration cycle, the refrigeration system performs heat release and heat absorption with latent heat of the refrigerant, so as to achieve heat transfer. In particular, a common principle of air conditioning is that heat is transferred from a heat source with a low temperature to a heat dissipation device with a higher temperature by a heat pump, and naturally, the heat flows in the opposite direction. This cycle is based on a universal gas law, PV=nRT, where P is air pressure, V is volume, R is normal gas constant, T is temperature, and n is the number of moles of gas.
In the refrigeration system, the refrigerant is a main cause of cooling the air. The refrigerant is a volatile gas that circulates in the refrigeration system as if it were blood in a human blood vessel, such that an endothermic reaction is conducted in the evaporator, and an exothermic reaction is conducted in the condenser. Therefore, in fact, the refrigeration system is not a device for producing cooling air, but a device for transferring heat energy from a room to an outside. Commercially available refrigerants are classified into different types according to pressure and usage requirements, such as R-123, RR-134, R-404A, R-407C, R-410A, R-600 and the like.
Please refer to FIG. 2, which is a pressure-enthalpy diagram showing relationship between pressure and enthalpy of a refrigeration cycle in an ideal environment. In the refrigeration system, a circulation composed of the compressor, the condenser, the refrigerant controller, and the evaporator is as follows. (1) The compressor is configured to compress a low-pressure and low-temperature gaseous refrigerant into a high-pressure and high-temperature gaseous refrigerant, which is also a source of power for the refrigerant to cycle through the refrigeration system. (2) The condenser is configured to cool the high-pressure and high-temperature gaseous refrigerant into a high-pressure and medium-temperature liquid refrigerant through a cooling medium, thereby performing an exothermic reaction at this end. (3) The refrigerant controller (also referred to as a reciprocator) is configured to depressurize the high-pressure and medium-temperature liquid refrigerant into a low-pressure and medium-temperature liquid refrigerant. The purpose of the pressure reduction is to match an evaporation temperature of the evaporator. Therefore, the lower the required temperature, the lower the pressure needs to be reduced. That is, a high-temperature evaporation occurs under high pressure, and low-temperature evaporation occurs under low pressure. (4) The evaporator is configured to evaporate the low-temperature and medium-temperature liquid refrigerant into the low-pressure and low-temperature gaseous refrigerant. Therefore, the evaporator is suitable for installation in an indoor cold room or a freezer. When the refrigerant is evaporated, the heat is absorbed, which causes the temperature of the indoor cold room or freezer to decrease, thereby reducing the temperature and freezing.
Please refer to FIG. 2 and FIG. 3, where FIG. 3 is pressure-enthalpy diagrams showing relationship between pressure and enthalpy of the refrigeration cycle in the ideal environment and in an actual environment, respectively. The pressure-enthalpy diagram A represents the relationship between pressure and enthalpy of the refrigeration cycle in the ideal environment, and the pressure-enthalpy diagram B represents the relationship between pressure and enthalpy of the refrigeration cycle in the actual environment. Firstly, from the pressure-enthalpy diagram A of the refrigeration cycle in the ideal environment, a path from point 1 to point 2 is an isentropic compression process, in which no heat energy is lost or obtained. A path from point 2 to point 3 or point 4 to point 1 is a condensation or evaporation process. This process is a change in isobaric pressure and does not result in loss or acquisition of thermal energy due to an influence of a pipeline. A path from point 3 to point 4 is a thermal expansion process. This process is a depressurization along an isenthalpic line and does not exchange heat with an outside world. Also, in this process, the refrigerant entering the compressor is in a saturated gas state, and the refrigerant leaving the condenser is in a saturated liquid state. However, it can be seen from the pressure-enthalpy diagram B of the refrigeration cycle in the actual environment that the refrigeration cycle in the actual environment will be affected by the temperature and humidity of a surrounding environment, which will inevitably cause heat loss.
Therefore, in order to increase a heat exchange rate and reduce the heat loss so that the refrigeration cycle performance can be approximated to the pressure-enthalpy diagram A of the refrigeration cycle in the ideal environment, the present disclosure enhances the heat exchangers in the condenser and the evaporator of the refrigeration system, such that the performances of heat exchangers, such as radiation, conduction, and convection are increased, thereby extending the lifespan of the refrigeration system. Specifically, a heat dissipation layer including nanomaterials is formed on fins of the heat exchangers of the condenser and the evaporator. Heat dissipating powders of different particle sizes are set to an appropriate ratio, and an adhesive is added (the specific structure and characteristics of the heat dissipation layer will be described in detail later). Therefore, a heat exchange area of the fins increases, and heat radiation and conduction of the fins are enhanced. The fins are controlled to be hydrophobic or hydrophilic. Also, a surface friction coefficient is decreased, so as to increase efficiency of thermal convection, such that the heat dissipation layer exhibits excellent UV and corrosion resistance. Furthermore, the greater the pressure difference between condensation and evaporation, the greater the energy will be required for the compressor. That is, as long as the temperature of condensation and evaporation can be decreased, a compression energy consumption can be reduced, thereby reducing a current and reducing a operation time of the compressor. Therefore, the present disclosure can also achieve advantages of improving cooling efficiency and reducing the use time to achieve energy saving. It has been proved by experiments that it not only achieves energy saving of 25 to 40 percent, but also achieves a best environmental protection without reducing the performance for five years.
Please refer to FIG. 4, which is a partial schematic diagram of a fin-type heat exchanger 10 according to the preferred embodiment of the present disclosure. Preferably, the fin-type heat exchanger 10 is used in the condenser and the evaporator of the refrigeration system. The fin-type heat exchanger 10 includes a plurality of fins 20 and a plurality of refrigerant pipes 30. The plurality of refrigerant pipes 30 are transversely passed through the plurality of fins 20 and disposed between the plurality of fins 20. Arrows in FIG. 4 indicate a cycle direction of the refrigerant. Air is heat-exchanged in an air passage between the plurality of refrigerant pipes 30 and the plurality of fins 20 by introducing the refrigerant into the plurality of refrigerant pipes 30.
Please refer to FIG. 5, which shows a partial enlarged view of a fin 20 of FIG. 4. The fin 20 is a heat dissipation plate with a composite structure manufactured by advanced technologies, and has high heat conduction, high heat capacity and heat radiation characteristics. The fin 20 includes a substrate 21 and a heat dissipation layer 22. The heat dissipation layer 22 may be formed on the substrate 21 by spraying, impregnating, laminating, or electrochemical method, but is not limited thereto. Preferably, material of the substrate 21 may be aluminum or copper, but is not limited thereto. The heat dissipation layer 22 includes a base layer 221, first heat dissipating powders 222, and second heat dissipating powders 223. The base layer 221 is made of a material that is capable of enhance heat conduction efficiency. The first heat dissipating powders 222 and the second heat dissipating powders 223 are configured to enhance heat radiation performance. Preferably, material of the first heat dissipating powders 222 is selected from the group consisting of nano-graphite, carbon nano-tube, titanium dioxide, boron nitride, carbon black, carbon fiber, metal powder, silicon carbide, aluminum oxide, aluminum nitride, aluminum oxide, silicon dioxide, and nano-diamond. Preferably, material of the second heat dissipating powders 223 is selected from the group consisting of nano-graphite, carbon nano-tube, boron nitride, carbon black, carbon fiber, metal powder, silicon carbide, aluminum nitride, and nano-diamond. Moreover, preferably, the first heat dissipating powders 222 present more than 0% to 35% of the heat dissipation layer 22 content, and the second heat dissipating powders 223 present in a range from 5% to 40% of the heat dissipation layer 22 content.
As shown in FIG. 5, the first heat dissipating powder 222 has a first particle size and the second heat dissipating powder 223 has a second particle size. In particular, the first particle size of the first heat dissipating powder 222 ranges between 300 nanometers and 750 nanometers, preferably, between 300 nanometers and 500 nanometers. The second particle size of the second heat dissipating powder 223 ranges between 1 nanometer and 35 nanometers, preferably, between 25 nanometers and 35 nanometers. The first heat dissipating powders 222 and the second heat dissipating powders 223 of different particle size sizes are disposed on the heat dissipation layer 22 to form a height difference on the surface, thereby increasing a heat exchange surface area of the fin 20 to enhance the heat dissipation performance.
The lower the humidity in a space the lower a cooling load of the refrigeration system. The cooling load refers to sensible heat (increased temperature) or latent heat (increased humidity) obtained by air in the space. The heat gain in a room is not necessarily transmitted to the air immediately (when a temperature of a surface of an object is lower than a dew-point temperature of the air, the moisture will condense on the surface of the object as dew, and this process is called condensation). In other words, reducing the dew-point temperature (i.e., humidity) can increase the performance of heat exchange. Therefore, when the fin-type heat exchanger 10 of the present disclosure is disposed in an indoor unit (e.g., the evaporator) of the refrigeration system, a ratio of the first particle size to the second particle size ranges between 10:1 and 30:1, such that the first heat dissipating powders 222 and the second heat dissipating powders 223 are formed a nano-sized geometrically complementary structure on a specific surface, so that the heat dissipation layer 22 is hydrophobic. Since the nano-sized concave and convex surface can stably stabilize gas atoms adsorbed thereon, a stable gas film is formed on the surface of the material. Therefore, for a water droplet having a radius of about 700 μm, if a surface of an object has a submicron or nanometer scale rough surface structure, the water droplet will form a solid-gas-liquid tristate interface on a contact surface with the surface of the object, so that there is an air interface between the water droplet and the surface of the object, and the rough surface structure is thus designed to create a hydrophobic surface. Furthermore, for the hydrophobic properties exhibited on a solid surface of a heterogeneous composite, air is sealed in pores of the surface structure due to a large depth of the roughened pores. Therefore, under an action of wetting, liquid does not completely adsorb or adhere to the solid surface, but is suspended above the solid surface and the air layer formed by the roughness. That is, the liquid is only partially in contact with the solid. Also, the air layer formed by the rough surface of the solid causes the liquid to suspend above the air layer without wetting the solid. Also, the more the air on the surface the greater the contact angle at the surface, even approaching 180 degrees.
When the fin-type heat exchanger 10 of the present disclosure is disposed in an outdoor unit (e.g., the condenser) of the refrigeration system, a ratio of the first particle size to the second particle size is preferably selected to be greater than 500:1 or more, and heat dissipation layer 22 is thus hydrophilic. When the heat dissipation layer 22 exhibits a hydrophilic property, a water film can be formed on the surface of the heat dissipation layer 22, thereby allowing the moisture to carry away the heat (gasification heat) together while evaporating. Therefore, when additional sprinklers are used to cool the outdoor unit, only a small amount of water should be used to achieve cooling. It has been experimentally confirmed that the outdoor unit has a good cooling performance by the hydrophilic heat dissipation layer 22, thereby improving the efficiency of the refrigeration system and effectively reducing an indoor temperature by 2 to 4° C. After trial calculation, about 10 to 20% of power consumption can be reduced to achieve energy saving.
In the present disclosure, the heat dissipation layer 22 also includes an adhesive (not shown in drawings) that covers the first heat dissipating powders 222 and the second heat dissipating powders 223 to reduce a surface friction coefficient of the heat dissipation layer 22. The thermal convection is mainly through eddying motion. Convective heat transfer refers to turbulent motion in a boundary layer to achieve heat transfer. That is, the fluid flowing in the heat exchange will generate friction with the surrounding fin 20, which generates a resistance force. The frictional resistance of the surface of the fin 20 affects the performance of heat conduction. Therefore, in the fin 20 of the present disclosure, the adhesive covers the first heat dissipating powders 222 and the second heat dissipating powders 223, and the surface of the fin 20 has a low friction coefficient, thereby increasing the thermal convection efficiency. It should be noted that is the fin-type heat exchanger 10 is disposed in the outdoor unit of the refrigeration system, material of the adhesive is preferably selected from the group consisting of polyacrylate and polyvinyl alcohol resin, such that the surface of the heat dissipation layer 22 exhibits hydrophilic properties. If the fin-type heat exchanger 10 is disposed in the indoor unit of the refrigeration system, material of the adhesive preferably includes siloxane, such that the surface of the heat dissipation layer 22 exhibits hydrophobic properties. On the other hand, ingredients of the adhesive preferably also include an anti-UV agent to provide the heat dissipation layer 22 with an excellent UV resistance.
In addition, a plurality of experimental results are listed below to demonstrate that excellent heat exchange efficiency can be achieved by applying the heat exchanger 10 of the present disclosure to the condenser and/or the evaporator in the refrigeration system.
(First) In the indoor unit of the refrigeration or air conditioning system, the fin having the heat dissipation layer of the present disclosure is compared with a fin of a heat exchanger which is subjected to an epoxy-coated treatment or made of a pure aluminum or pure copper material that has not been subjected to a surface treatment in the prior art, and the present disclosure can provide excellent heat conduction, heat diffusion, heat exchange, and hydrophobic characteristic. In this embodiment, the first heat dissipating powders and the second heat dissipating powders present in a range from about 10% to 20% of the heat dissipation layer content, and the results are as shown in a table as follow.


the present	epoxy-coated
disclosure	treatment	aluminum	copper

thermal conductivity	XY axis	300~450	0.42	237	401
(W/m × k)	Z axis	300~450	0.42	237	401

thermal diffusivity (cm²/S)	2	0.2	0.9	0.39
surface emissivity	>0.92	0.08	0.02~0.1	0.04~0.6
water contact angle (degree)	>150	≈30	<50	<60

(Second) The fin-type heat exchanger 10 of the present disclosure is applied to an indoor unit of a 2.8 KW to 2.8 KW air conditioning system. A general R-410 and 2.8 KW fixed-frequency air conditioner is tested for three months, a heat exchanger not provided with the heat dissipation layer 22 or the present disclosure behaves as follows. A temperature of the air entering an evaporation section from an expansion section is typically 8 to 12 degrees. A temperature of the air entering an compression section through the evaporator is typically 8 to 18 degrees. A temperature of the air entering the condenser through the compressor will be 20 to 25 degrees higher than an ambient temperature depending on a temperature and humidity of an environment. A temperature of the air leaving the condenser is about 4 to 8 degrees higher than a room temperature. In contrast, after the fins are provided with the heat dissipation layer 22 of the present disclosure, the temperature of the air entering the evaporation section from the expansion section is reduced to about 4 to 12 degrees. The temperature of the air entering the compressor is reduced to 0 to 8 degrees. The temperature of the air entering the condenser from the compressor will be 16 to 22 degrees higher than the room temperature. The temperature of the air leaving the condenser is about 2 to 4 degrees higher than the room temperature. In addition, a dehumidification rate is higher than 25%.
(Third) The fin-type heat exchanger 10 of the present disclosure is applied to an indoor unit of an air conditioning system that drives 4.1 KW with 2.8 KW. The R-410 and 2.8 KW fixed-frequency air conditioner is replaced with a 4.1 KW indoor unit as an example. After the fins are provided with the heat dissipation layer 22 of the present disclosure, a temperature of the air entering the evaporation section from the expansion section is reduced to about 4 to 12 degrees. A temperature of the air entering the compressor is reduced to 4 to 8 degrees. A temperature of the air entering the condenser from the compressor will be 16 to 20 degrees higher than the room temperature. A temperature of the air leaving the condenser is about 2 to 3 degrees higher than the room temperature. In addition, a dehumidification rate is higher than 35%.
In conclusion, the present disclosure discloses that the heat dissipation layer including nano-materials is formed on fins of the heat exchanger. The heat dissipation layer includes heat dissipating powders of different particle sizes, so that a heat exchange area of the fins is increased and heat radiation and conductivity of the fins are enhanced. Also, the heat dissipating powders of different particle sizes are set to an appropriate ratio for controlling the fin to be hydrophobic or hydrophilic, such that the fin is formed to have a high moisture content or self-cleaning ability. Furthermore, by adding the adhesive to the heat dissipation layer, the surface friction coefficient can be reduced to improve efficiency of thermal convection, such that the heat dissipation layer exhibits excellent UV and corrosion resistance.
The above descriptions are merely preferable embodiments of the present disclosure. Any modification or replacement made by those skilled in the art without departing from the spirit and principle of the present disclosure should fall within the protection scope of the present disclosure.

Claims

1. A fin-type heat exchanger, comprising: a plurality of fins and a plurality of refrigerant pipes transversely passed through the plurality of fins and disposed between the plurality of fins, wherein air is heat-exchanged in an air passage between the plurality of refrigerant pipes and the plurality of fins by introducing a refrigerant into the plurality of refrigerant pipes;

wherein a surface of each of the fins comprises a heat dissipation layer, and the heat dissipation layer comprises a plurality of first heat dissipating powders with a first particle size and a plurality of second heat dissipating powders with a second particle size; and

wherein material of the heat dissipation layer comprises nano-graphite, carbon nano-tube, boron nitride, or nano-diamond.

2. The fin-type heat exchanger as claimed in claim 1, wherein material of each of the first heat dissipating powders is selected from the group consisting of the nano-graphite, the carbon nano-tube, titanium dioxide, the boron nitride, carbon black, carbon fiber, metal powder, silicon carbide, aluminum oxide, aluminum nitride, aluminum oxide, silicon dioxide, and the nano-diamond.

3. The fin-type heat exchanger as claimed in claim 1, wherein material of each of the second heat dissipating powders is selected from the group consisting of the nano-graphite, the carbon nano-tube, the boron nitride, carbon black, carbon fiber, metal powder, silicon carbide, aluminum nitride, and the nano-diamond.

4. The fin-type heat exchanger as claimed in claim 1, wherein the first particle size of each of the first heat dissipating powders ranges between 300 nanometers and 500 nanometers.

5. The fin-type heat exchanger as claimed in claim 1, wherein the second particle size of each of the second heat dissipating powders ranges between 25 nanometers and 35 nanometers.

6. The fin-type heat exchanger as claimed in claim 1, wherein the first heat dissipating powders present more than 0% to 35% of the heat dissipation layer content.

7. The fin-type heat exchanger as claimed in claim 1, wherein the second heat dissipating powders present in a range from 5% to 40% of the heat dissipation layer content.

8. The fin-type heat exchanger as claimed in claim 1, wherein of the heat dissipation layer further comprises an adhesive covering the first heat dissipating powders and the second heat dissipating powders, and the adhesive is configured to reduce a surface friction coefficient of the heat dissipation layer, and wherein material of the adhesive is selected from the group consisting of polyacrylate, a polyvinyl alcohol resin, and siloxane.

9. The fin-type heat exchanger as claimed in claim 1, wherein in response to the fin-type heat exchanger is disposed in an indoor unit of a refrigeration system, a ratio of the first particle size to the second particle size ranges between 10:1 and 30:1, such that the heat dissipation layer is hydrophobic.

10. The fin-type heat exchanger as claimed in claim 1, wherein in response to the fin-type heat exchanger is disposed in an outdoor unit of a refrigeration system, a ratio of the first particle size to the second particle size is greater than 500:1, such that the heat dissipation layer is hydrophilic.