Patent Description:
In related technologies, due to low surface temperature of heat exchangers in the operation of heat exchange systems, when the temperature is lower than the dew point temperature, condensed water may be generated on a surface, and even frost may form, thereby affecting the heat exchange efficiency of the heat exchangers. Therefore, related heat exchangers need dehumidification treatment. In related technologies, the surface of the heat exchanger is treated with a lithium salt desiccant or a silica gel hygroscopic material. However, the lithium salt desiccant is not friendly to metal surfaces, and the silicone hygroscopic material is not sticky. Therefore, it is necessary to add an additional adhesive to make it adhere to the surface of the heat exchanger. In summary, the heat exchanger in the related technologies needs to be improved.

A heat exchanger according to the present invention is provided according to independent claim <NUM>.

According to another aspect of the present disclosure, a heat exchange system is provided. The heat exchange system comprises a compressor, at least one first heat exchanger, a throttling device and at least one second heat exchanger. At least partial surface of the first heat exchanger and/or the second heat exchanger is covered with a hygroscopic colloid. When a refrigerant flows in the heat exchange system, the refrigerant flows into the first heat exchanger through the compressor, flows into the throttling device after heat exchange occurs in the first heat exchanger, then flows into the second heat exchanger and flows into the compressor again after heat exchange occurs in the second heat exchanger.

At least partial surface of the heat exchanger of the present disclosure is covered with a hygroscopic colloid material. The hygroscopic colloidal material can be directly covered on a metal surface due to its adhesiveness to the metal surface, and the hygroscopic colloidal material is friendly to metal surfaces.

Here, exemplary embodiments will be described in detail, and examples thereof are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, same numbers in different drawings indicate the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all implementation embodiments consistent with the present disclosure. On the contrary, they are only examples of devices and methods consistent with some aspects of the present disclosure as described in detail in the accompanying claims.

The exemplary embodiments of the present disclosure will be described in detail below with reference to the drawings. In the case of no conflict, the following embodiments and features in the implementation can be combined with each other.

Related heat exchangers, especially in air conditioning systems, when used as an evaporator during system operation, due to their low surface temperature, condensed water may be generated on the outer surface of the heat exchanger, which may even further cause frosting. However, the generation of condensed water or frost will cause the heat exchange efficiency of the heat exchanger to decrease, thereby making it difficult for the heat exchanger to exert better heat exchange performance. Hence, it is necessary to avoid condensed water or frost on the outer surface of the heat exchanger. One way is to bond hygroscopic or desiccant materials on the surface of the heat exchanger, such as silica gel and its physical or chemical compound desiccant, so as to reduce the impact of the wet load on the air conditioning systems. However since silica gel itself is not sticky, it is necessary to spray a layer of adhesive on the surface of the heat exchanger first. The adhesive can bond silica gel or its physical or chemical composite desiccant material to the metal surface. Since silica gel has a porous structure, the use of a binder will cause the micropores of silica gel to be blocked, thereby reducing moisture absorption. Moreover, the use of adhesives may also be detrimental to the heat exchange of the heat exchanger. In addition, the moisture absorption of silica gel itself (about <NUM>/g) is relatively small. Although halogen salts and silica gel can be used in heat exchangers, the moisture absorption performance is greatly improved, but after the halogen salts absorb moisture, electrochemical corrosion will occur on the metal surface, which shortens the life of the heat exchanger.

An embodiment of the present disclosure provides a heat exchanger which is simple to manufacture. The outer surface of the heat exchanger is covered with a hygroscopic colloid. Due to the viscosity of the hygroscopic colloid itself, the fluidity of the gel after drying is not strong. Therefore, no additional binder is required. At room temperature, a pH value of the hygroscopic colloid is between <NUM> to <NUM>, and it can be directly coated on a metal surface, such as a surface of aluminum or copper, and it is friendly to the metal surface. The hygroscopic colloidal material has a large moisture absorption capacity, which is better than silica gel and its composite materials. Inventors believe that the solute properties of the hygroscopic colloidal material are stable. For example, the solute of the zinc oxide gel is the metal oxide zinc oxide, and the solute material is more friendly to metals, especially copper or aluminum. At the same time, metal oxides such as zinc oxide have good thermal conductivity, and their covering on the surface of the heat exchanger can also relatively reduce the influence of the adhesive on the heat exchange performance of the heat exchanger.

The application of zinc oxide gel material to heat exchanger dehumidification effectively solves the problems of low moisture absorption of existing materials and the need for binders. The embodiment of the present disclosure provides a heat exchange system including the heat exchanger. The heat exchanger can be used as an evaporator in a heat pump air conditioning system. It is easy to understand that, in addition to being used as a heat exchanger in a heat pump system, the heat exchanger can also be used in other occasions where heat is exchanged with air. There is no restriction here.

The hygroscopic colloid covered by the heat exchanger of this embodiment includes but is not limited to zinc oxide gel. This embodiment takes zinc oxide material as an example. Of course, according to the rules of the periodic table and the periodic law of the elements, for example, the sol material formed by the same group of elements or elements near the diagonal also has similar properties, and is also within the protection scope of the present disclosure.

<FIG> shows a preparation flow chart of a zinc oxide gel of a method for making zinc oxide gel, which includes the following steps:.

S1: weighing <NUM> of zinc acetate dihydrate, of which the molecular formula is Zn(CH<NUM>COO)<NUM>·<NUM><NUM>O, used as a main raw material for the reaction in order to provide the source of zinc;.

S2: measuring <NUM> ethanolamine, of which the molecular formula is H<NUM>N(CH<NUM>)<NUM>OH, used to stabilize zinc acetate dihydrate from decomposition in the air;.

S3: mixing the zinc acetate dihydrate in the step S1 with the ethanolamine in the step S2 in a mixture; then, adding <NUM> of isopropanol to the mixture, of which the molecular formula is (CH<NUM>)<NUM>CHOH, used to dissolve the zinc acetate dehydrate; and reacting with the zinc acetate dihydrate under heating at <NUM>;.

S4: after the solution in the step S3 gradually becomes transparent, adding sodium bicarbonate to adjust the pH to <NUM> to <NUM>.

A reaction equation of the above reaction is:.

4Zn(CH<NUM>COO)<NUM>·<NUM><NUM>O→Zn<NUM>O(CH<NUM>COO)<NUM> + <NUM><NUM>O+CH<NUM>COOH.

CH<NUM>COOH+NaHCO<NUM>→CH<NUM>COONa+H<NUM>O+CO<NUM> ↑.

It should be noted that in the step S4, to adjust the pH value, some salts that are weakly alkaline after hydrolysis, such as sodium bicarbonate, or weak bases, such as ammonia can be selected. In this way, it is convenient to control the pH value to a required pH value. Among them, the heating temperature in the step S3 can be <NUM> to <NUM>, for example, it can be heated at <NUM>. The heating method can be water bath heating or direct heating. In this way, it is beneficial to accelerate the dissolution of zinc acetate dihydrate. The stirring speed can be selected from <NUM> to <NUM> r/min. In this embodiment, the stirring speed is <NUM> r/min.

<FIG> shows a schematic diagram of a comparison of the moisture absorption properties of zinc oxide gel and other three materials. Among them, M1 is zinc oxide gel material, M2 and M3 are respectively mesoporous silica gel (pore size is about <NUM> to <NUM>) and macroporous silica gel (pore size is about <NUM> to <NUM>), and M4 is a silica gel/glycerol composite material. The moisture absorption is defined as the percentage of the water absorbed by a certain mass of the material to the same mass without water absorption. As shown in the figure, the test was performed at <NUM> and <NUM>% RH. Among them, the moisture absorption performance of M1 zinc oxide gel is better than M2 and M3, and also better than M4 silica gel/glycerol composite.

After <NUM> hours of absorbing moisture, the moisture absorption of M1 zinc oxide gel reaches <NUM>%, and the moisture absorption of M2 is <NUM>%. The moisture absorption of M4 silica gel/glycerol composite is <NUM>%, which is <NUM>% more than M2. This is mainly because after the addition of glycerol, the saturated vapor pressure of silica gel is reduced, which can absorb water faster. After <NUM> hours, the moisture absorption of M3 reaches <NUM>%, and the moisture absorption is the smallest. Because of its large pore size, it will also release moisture while absorbing moisture.

After <NUM> hours, the moisture absorption of M1 is the largest, reaching <NUM>%. It is followed by M2 of which the moisture absorption is <NUM>%. The moisture absorption of M3 is <NUM>%. Because of the limited size of silica gel pores, after glycerol is adsorbed inside, the volume that can be used for water storage becomes smaller. The last is M4 of which the moisture absorption is <NUM>%. The inventors believe that the above result is mainly because the zinc oxide gel contains a large amount of hydrophilic groups.

<FIG> shows a schematic diagram of the desorption performance comparison among the zinc oxide gel and other three materials. Among them, M1 is a zinc oxide gel material, M2 and M3 are mesoporous silica gel (pore size is about <NUM> to <NUM>) and macroporous silica gel (pore size is about <NUM> to <NUM>), and M4 is a silica gel/glycerol composite material.

A regeneration rate is defined as the percentage of water desorbed by a certain mass of the material to the original saturated water. As shown in <FIG>, at a temperature of <NUM>, M1 has the fastest regeneration speed. After <NUM> hours, the regeneration rate is <NUM>%. Followed by M2, its regeneration rate is <NUM>%. The main reason is that high temperature accelerates water decomposition and absorption. At the same time, due to the large moisture absorption of M1 and M2, the regeneration rate is high. M3 has a regeneration rate of <NUM>% at <NUM> hours, while the regeneration rate of M4 is only <NUM>%. The regeneration rate determines the desorption performance of the hygroscopic material. When the hygroscopic material is covered on the surface of the heat exchanger, a good desorption performance is beneficial to the regeneration of the hygroscopic material.

As shown in <FIG>, the specific implementation of the heat exchanger of the present disclosure will be described in conjunction with other figures when necessary.

The heat exchanger <NUM> of an embodiment of the present disclosure includes a collecting pipe <NUM>, a plurality of heat exchange tubes <NUM> and at least one fin <NUM>. The collecting pipe <NUM> has an inner cavity (not shown in the figure) for a refrigerant to circulate, and the shape of the collecting pipe <NUM> is a circular pipe. The number of the collecting pipe <NUM> is two, namely a first collecting pipe <NUM> and a second collecting pipe <NUM>. The first collecting pipe <NUM> and the second collecting pipe <NUM> may be arranged substantially in parallel. A communication structure can be arranged between adjacent collecting pipes and flow paths can be set as needed, which is not limited here. The heat exchanger in this embodiment includes two such collecting pipes. In this embodiment, it is noted that when the heat exchanger <NUM> and air generally undergo heat exchange only one time, it is often referred to as a single-layer heat exchanger in the industry.

Of course, in some other embodiments, the collecting pipe <NUM> may also be a D-shaped or square pipe. The specific shape of the collecting pipe <NUM> is not limited, as long as its burst pressure meets the needs of the system. The relative position of the collecting pipe <NUM> is also not limited, as long as it meets the actual installation requirements. The collecting pipe <NUM> in the embodiment of the present disclosure is a round pipe as an example.

There are a plurality of the heat exchange tubes <NUM> which are arranged along an axial direction of the collecting pipe <NUM> and are arranged substantially in parallel. Each of the plurality of heat exchange tubes <NUM> has a first end <NUM> and a second end <NUM>. As shown in <FIG>, the heat exchange tube <NUM> includes a first heat exchange tube <NUM> and a second heat exchange tube <NUM> which are arranged side by side. A direction in which the first end <NUM> of the heat exchange tube <NUM> extends to the second end <NUM> is a length direction of the heat exchange tube. It is noted that the heat exchange tube may be a bent heat exchange tube. The length direction is not limited to a linear direction. In other words, an extension direction of the heat exchange tube may be the linear direction or a non-linear direction, which is not limited here. The first end <NUM> of the first heat exchange tube <NUM> is connected to the first collecting pipe <NUM>. The second end <NUM> of the first heat exchange tube <NUM> is connected to the second collecting pipe <NUM>. Similarly, the first end <NUM> of the second heat exchange tube <NUM> is connected to the first collecting pipe <NUM>. The second end <NUM> of the second heat exchange tube <NUM> is connected to the second collecting pipe <NUM>. The first heat exchange tube <NUM> and the second heat exchange tube <NUM> are arranged substantially in parallel. The heat exchange tube <NUM> has an inner cavity (not shown in the figure) for the refrigerant to circulate. Such connection makes the inner cavity of the heat exchange tube <NUM> communicate with the inner cavity of the collecting pipe <NUM> so as to form a refrigerant flow channel of the heat exchanger <NUM> (not shown in the figure). The refrigerant can circulate in the heat exchange channel, and the heat exchange can be achieved through the heat exchanger <NUM>.

When the heat exchanger <NUM> is used as an evaporator in a heat exchange system, its outer surface usually has a lower temperature. The moisture in the air is easy to condense on the surface of the evaporator, forming a water film, or further frost, which affects the heat exchange performance of the evaporator. At least partial surface of the heat exchanger is covered with the hygroscopic colloid <NUM>. The hygroscopic colloid <NUM> can absorb moisture or moisture on the surface of the evaporator through its unique hygroscopic characteristics, so as to delay or avoid the formation of water film on the surface of the evaporator, and then to delay or avoid frost on the evaporator surface. Finally, the heat exchange performance of the evaporator is maintained to a certain extent, or the rapid decline of the heat exchange performance of the evaporator is delayed. It is worth noting that the surface of the heat exchanger in the related art is covered with functional materials, such as corrosion-resistant materials. Specifically, it is covered on the outer surface of the entire heat exchanger. Since the functional materials will affect the heat transfer effect, the heat transfer performance of the entire heat exchanger will decrease. However, the hygroscopic colloid <NUM> used in the present disclosure, due to the viscosity of the hygroscopic colloid itself, it does not have strong fluidity in a gel state after drying, so no additional binder is required. This has little effect on the heat exchange performance of the heat exchanger. The hygroscopic colloid <NUM> can be directly coated on a metal surface, such as a surface of aluminum or copper. The hygroscopic colloid <NUM> is friendly to the metal surface. The hygroscopic colloid <NUM> material has a large moisture absorption capacity, which is better than silica gel and its composite materials. The inventors believe that the solute properties of hygroscopic colloidal materials are stable. For example, the solute of zinc oxide gel is metal oxide zinc oxide. The solute materials are relatively friendly to metals. At the same time, metal oxides, such as zinc oxide, have good thermal conductivity. The covering on the surface of the heat exchanger can also relatively reduce the influence of the heat exchange performance of the heat exchanger. In addition, the hygroscopic colloid <NUM> may be covered on part of the outer surface of the heat exchanger, especially part of the fin. In other words, the hygroscopic colloid is covered on the frost-prone portions of the heat exchanger, and the hygroscopicity of the hygroscopic colloid <NUM> is used to delay the generation of water film or frost to a certain extent. In this way, while ensuring the heat exchange efficiency of the heat exchanger, it can also delay the attenuation of the heat exchange efficiency to a certain extent. The specific overlay structure and overlay method will be described in detail in the following description.

It should be noted that the heat exchange tube <NUM>, also known as a flat tube in the industry, has an inner cavity inside for the refrigerant to circulate. As shown in <FIG>, the inner cavity of the heat exchange tube <NUM> (not shown in the figure) is usually separated by ribs <NUM> into a plurality of refrigerant flow channels <NUM>. With this arrangement, not only the heat exchange area of the heat exchange tube <NUM> is increased so that the heat exchange efficiency is improved, but also the inner surface of the heat exchange tube <NUM> can be provided with tiny protrusions <NUM> which can form a capillary effect to enhance heat exchange. Shapes of the protrusions <NUM> can be sawtooth, wave, triangle, etc., (not shown in the figure), and the shapes can be set as required. Adjacent channels <NUM> are isolated from each other. A plurality of channels <NUM> are arranged in a row and collectively affect a width of the heat exchange tube <NUM>. The heat exchange tube <NUM> is flat as a whole, and its length is greater than its width, and its width is greater than its thickness. The heat exchange tube mentioned here is not limited to this type, and may be of other forms. For example, adjacent channels may not be completely isolated. For another example, all channels can be arranged in two rows, as long as the width is still greater than the thickness. As shown in <FIG>, the heat exchanger <NUM> of the embodiment of the present disclosure further includes the fins <NUM>.

As shown in <FIG>, the fin <NUM> is a window fin and has wave crest portions <NUM> and wave trough portions <NUM>. It is noted that in other embodiments, the fin may also be a fin without opening windows. The shape of the fin can be roughly corrugated, or it can be a profile. A cross section of the fin can be a sine wave or an approximate sine wave, or a sawtooth wave, as long as it meets the requirements, and its specific structure is not limited.

In the embodiment of the present disclosure, the fin <NUM> has a wave shape as a whole. An extension direction of the wave shape is a length direction of the heat exchange tube <NUM>. The wave crest portions <NUM> and the wave trough portions <NUM> are arranged one by one at intervals. The fin <NUM> is arranged between two adjacent heat exchange tubes <NUM>. The wave crest portions <NUM> are at least partially in contact with the heat exchange tube <NUM>. The wave trough portions <NUM> are at least partially in contact with the heat exchange tube <NUM>. The highest point of the wave crest portions <NUM> is a wave crest surface <NUM>, and the lowest point of the wave trough portions <NUM> is a wave trough surface <NUM>. The extension direction of the wave crest portions <NUM> and the wave trough portions <NUM> at intervals defining the length direction of the fin <NUM> (the X direction in the figure). A vertical direction between the plane of the wave crest surface <NUM> and the plane of the wave trough surface <NUM> defines the height direction of the fin (such as the Z direction in the figure). It can be seen that the length direction of the fin <NUM> is the same as the length direction of the heat exchange tube <NUM> (the X direction in the figure). A width direction of the fin <NUM> is the same as the width direction of the heat exchange tube <NUM> (the Y direction in the figure). The distance between the heat exchange tubes <NUM> is the height direction of the fin <NUM> (the Z direction in the figure).

As shown in <FIG>, in an embodiment of the present disclosure, a part of the surface of the fin <NUM> is covered with the hygroscopic colloid <NUM>. Specifically, the part of the surface is a location where the wave crest portions <NUM> and/or the wave trough portions <NUM> are covered with the hygroscopic colloid <NUM>. The wave crest portions <NUM> and/or the wave trough portions <NUM> of the fin <NUM> are covered with the hygroscopic colloid <NUM>, and the wave crest portions <NUM> or the wave trough portions <NUM> occupy <NUM>% to <NUM>% of the overall height of the fin <NUM>. In other words, the wave crest portions <NUM> of the fin <NUM> extend from the wave crest surface <NUM> to the wave trough surface <NUM> to <NUM>%-<NUM>% of the height of the fin <NUM>. The wave crest portions <NUM> are covered with the hygroscopic colloid <NUM>. The wave trough portions <NUM> of the fin <NUM> extend from the wave trough surface <NUM> to the wave crest surface <NUM> to <NUM>% to <NUM>% of the height of the fin <NUM>. The wave trough portions <NUM> are covered with the hygroscopic colloid <NUM>. It should be noted that the hygroscopic colloid <NUM> covered on the wave crest portions <NUM> and the wave trough portions <NUM> may be uniformly covered or non-uniformly covered. The covering thickness of the hygroscopic colloid is <NUM> to <NUM>, such as <NUM>, <NUM>, <NUM>, etc. It should be noted that the thickness of the above-mentioned hygroscopic colloid <NUM> is approximately the thickness. Due to the limitation of the process or other conditions, it may not achieve a completely uniform covering effect, or the covering is non-uniform, which is not limited here.

As shown in the embodiment shown in <FIG>, part of the surface of the fin <NUM> is covered with the hygroscopic colloid <NUM>. That is, the area A in <FIG> is covered with the hygroscopic colloid <NUM>. The partial surface covering is covering from the end of the fin <NUM> along the length direction of the fin <NUM>. The covering area occupies <NUM>% to <NUM>% of the total length of the fin <NUM>. In other words, along the length direction of the fin <NUM> (i.e., the X direction in the figure), the total length of the fin <NUM> is L, which is covered from the end <NUM> of the first end of the fin <NUM>. The length of the part of the fin covering the hygroscopic colloid occupies <NUM>% to <NUM>% of the total length L of the fin <NUM>. For example, the length of the part of the fin covering the hygroscopic colloid occupies <NUM>% of the total length of the fin <NUM>. With such a structure, when the heat exchanger <NUM> is in a vertical state during actual use, the condensed water in the air is more likely to flow from the upper fin to the lower fin under the influence of force, and accumulate in the lower fin area. While avoiding the decrease in heat exchange efficiency caused by the overall covering, it can absorb moisture in the frost-prone portions to delay frost formation, thereby delaying the rate of heat exchange performance degradation of the heat exchanger. Wherein the vertical state means that the collecting pipe <NUM> is arranged approximately horizontally, that is, its center line is approximately horizontal, or there is an angle with the horizontal line but the angle is small. At this time, the heat exchange tube <NUM> is generally arranged in the vertical state.

As shown in <FIG>, it is a schematic diagram of the comparison before and after the fin <NUM> is partially covered in accordance with another embodiment of the present disclosure. Part of the surface of the fin <NUM> is covered with the hygroscopic colloid <NUM>. The partial surface covering is covering from the end of the fin <NUM> along the width direction of the fin <NUM> (i.e., the Y direction in the figure). The covering area occupies <NUM>% to <NUM>% of the total width of the fin <NUM>. In other words, it is covered from the end <NUM> of the third end of the fin <NUM> along the width direction of the fin <NUM> (i.e., the Y direction in the figure). The width of the part of the fin covering the hygroscopic colloid <NUM> occupies <NUM>% to <NUM>% of the total width of the fin <NUM>. For example, the width of the part of the fin <NUM> covering the hygroscopic colloid <NUM> occupies <NUM>% of the total width of the fin <NUM>. Wherein, B1 is a schematic view of the fin <NUM> not being covered, and B3 is a schematic diagram of partial covering along the width direction Y The covering area occupies roughly <NUM>% of the width of the fin <NUM>. With such a structure, when the heat exchanger <NUM> is used in a horizontal state during actual use, the air inlet section is partially covered with the fin <NUM> to absorb water molecules in the air, which can avoid the decrease in heat exchange efficiency caused by the overall covering. The frost-prone portions (here mainly refers to the air inlet, that is, a first side of the heat exchanger <NUM>, which is also knowns as a windward side of the heat exchanger <NUM>) absorbs moisture and delays frosting, thereby delaying the time of the deterioration of the heat exchange performance of the heat exchanger. Wherein, the horizontal state means that the collecting pipe is arranged approximately horizontally. That is, the center line is roughly horizontal, or there is an angle with the horizontal line but the angle is small. At this time, the heat exchange tube is arranged in a generally vertical state, that is, the length direction of the heat exchange tube is roughly parallel to the X direction. Wherein, the horizontal state means that the collecting pipe is arranged substantially vertically. That is, the center line is approximately vertical, or there is an angle between the center line and the vertical line but the angle is small. At this time, the heat exchange tube is generally arranged in the horizontal state, that is, the length direction of the heat exchange tube is roughly parallel to the horizontal direction.

<FIG> shows a heat exchanger <NUM> according to another embodiment of the present disclosure. The heat exchanger <NUM> also includes a collecting pipe <NUM>, a plurality of heat exchange tubes <NUM> and fins <NUM>. The difference from the heat exchanger <NUM> is that the plurality of heat exchange tubes <NUM> of the heat exchanger <NUM> have a bent portion <NUM>. As shown in <FIG>, the heat exchanger <NUM> has the bent portion <NUM>. Of course, in some other embodiments, there may be more than two bent portion <NUM>, which can be set according to actual needs. It is noted that, when the heat exchanger <NUM> and air undergo heat exchange more than one time, it is often referred to as a multi-layer heat exchanger or an N-layer heat exchanger in the industry.

As shown in <FIG> and combined with the foregoing embodiments, taking the heat exchanger <NUM> as an example, the heat exchanger <NUM> has a first collecting pipe <NUM>, a second collecting pipe <NUM>, the plurality of heat exchange tubes <NUM> and the fins <NUM>. The first collecting pipe <NUM> and the second collecting pipe <NUM> are arranged substantially in parallel. One end of each heat exchange tube <NUM> is connected to the first collecting pipe <NUM> and the other end is connected to the second collecting pipe <NUM>. The inner cavities of the first collecting pipe <NUM>, the second collecting pipe <NUM>, and the plurality of heat exchange tubes <NUM> are communicated with each other so as to form a refrigerant flow channel (not shown in the figure). Each heat exchange tube <NUM> has the bent portion <NUM> and a straight tube section <NUM>. There is one bent portion <NUM>. There are two straight tube sections <NUM>, namely a first straight tube section <NUM> and a second straight tube section <NUM>. The fins <NUM> are arranged between the adjacent heat exchange tubes <NUM>. The length direction of the fin <NUM> is substantially the same as the length direction of the heat exchange tube <NUM>. Specifically, the fins <NUM> are arranged between the first straight tube sections <NUM> of the adjacent heat exchange tubes <NUM> and/or between the second straight tube sections <NUM> of the adjacent heat exchange tubes <NUM>. Part of the surface of the fin <NUM> is covered with the hygroscopic colloid <NUM>. For example, the fin <NUM> arranged between the first straight tube sections <NUM> of the heat exchange tube <NUM> is covered with the hygroscopic colloid <NUM>. At the same time, the fin <NUM> arranged between the second straight tube sections <NUM> of the heat exchange tube <NUM> is not covered with the hygroscopic colloid <NUM>. Alternatively, the fin <NUM> arranged between the first straight tube sections <NUM> of the heat exchange tube <NUM> is not covered with the hygroscopic colloid <NUM>. At the same time, the fins <NUM> arranged between the second straight tube sections <NUM> of the heat exchange tube <NUM> are covered with the hygroscopic colloid <NUM>. The above structures are all covering parts of the fin <NUM> of the heat exchanger <NUM>.

It should be noted that the FPI (FPI, namely Fin Per Inch, is a unit commonly used in the industry to express the density of fins) of the fins <NUM> arranged between the first straight tube sections <NUM> of the heat exchange tube <NUM> and the FPI of the fins <NUM> between the second straight tube sections <NUM> of the heat exchange tube <NUM> may be the same or different. As shown in <FIG>, when the heat exchanger <NUM> is used as an outdoor heat exchanger in an actual heat pump system, the first straight tube sections <NUM> serve as a first side (that is, a windward side), and the second straight tube sections <NUM> serve as a second side (that is, a leeward side), the fins <NUM> between the first straight tube sections <NUM> of the heat exchange tube <NUM> are covered with the hygroscopic colloid <NUM>, while the fins <NUM> between the second straight tube sections <NUM> are not covered with the hygroscopic colloid <NUM>. At the same time, the FPI of the fins <NUM> arranged between the first straight tube sections <NUM> is smaller than the FPI of the fins <NUM> arranged between the second straight tube sections <NUM>. In this way, the heat transfer efficiency of the fins <NUM> between the first straight tube sections <NUM> is reduced due to the hygroscopic colloid <NUM> being covered, and the FPI of the fins <NUM> between the second straight tube sections <NUM> on the leeward side is increased to be compensated.

As shown in <FIG>, this is a heat exchanger <NUM> according to another embodiment of the present disclosure. The heat exchanger is a tube-fin heat exchanger. The heat exchanger <NUM> includes heat exchange tubes <NUM> and fins <NUM>, wherein the heat exchange tubes <NUM> are usually copper tubes. The heat exchanger is also called a copper tube fin heat exchanger. When the heat exchanger <NUM> is used in a heat exchange system, the refrigerant can enter the heat exchanger <NUM> through the first inlet and outlet <NUM>, exchange heat with the heat exchange tubes <NUM>, and then flow out of the heat exchanger from the outlet <NUM>. The heat exchanger, as shown by the arrow in the figure, is the flow direction of the refrigerant. It should be noted that the surface of the heat exchange tubes <NUM> and/or the fins <NUM> may be covered with the hygroscopic colloid <NUM>. The covering may be a partial covering or a complete covering. The covering method is the same as the heat exchanger <NUM> and the heat exchanger <NUM> described above. The thickness of the covering is also the same as that described above, which will not be repeated here.

It should be noted that, in the embodiment of the present disclosure, a method of making a single-layer heat exchanger and a multi-layer heat exchanger having a partial surface of the fin covered with a hygroscopic colloid is disclosed.

Taking the single-layer heat exchanger <NUM> as an example, the collecting pipe <NUM>, the plurality of heat exchange tubes <NUM> and the heat exchange fins <NUM> are assembled, and then spraying is performed. That is, the sol in which the hygroscopic colloid <NUM> is dissolved is coated on a partial area of the surface of the heat exchanger <NUM> by spraying. During the spraying process, it is necessary to control the spraying of the hygroscopic colloid <NUM> to the area of the fins to achieve partial coverage. For example, when covering the wave crest portions <NUM> and/or the wave trough portions <NUM> of the fins <NUM>, it can be implemented in a manner similar to spraying a slogan. That is, a solid sheet material is used to block the middle area of the fins <NUM> to expose the area to be sprayed, and then spraying is performed. It is ensured that only the wave crest portions31 and/or the wave trough portions <NUM> are covered, and the covering effect is shown in <FIG>.

Taking the multi-layer heat exchanger <NUM> as an example, the collecting pipe <NUM>, the plurality of heat exchange tubes <NUM> and the heat exchange fins <NUM> are assembled, and the first side area (that is, the windward side area) of the heat exchanger <NUM>, the first straight tube sections <NUM> for example, is immersed in the sol in which the hygroscopic colloid <NUM> is dissolved, and then left to stand to dry. After the hygroscopic colloid <NUM> is tightly adsorbed on the fins <NUM> of the heat exchanger <NUM>, the next step is performed as needed. The thickness of the hygroscopic colloid covering the surface of the heat exchanger <NUM> is <NUM> to <NUM>, such as <NUM>, <NUM>, <NUM>, etc., so that the moisture absorption can be guaranteed. The comparison diagrams of the fins before and after covering are shown in <FIG> and <FIG>, where B1 represents an uncoated fin, B2 represents a partial coating of the fin in the width direction, and B3 represents a complete coating in the width direction of the fin. The covering thickness b is controlled by the number of immersion into the container. That is to say, if it is necessary to increase the covering thickness, it can be left to dry after being immersed, and after the hygroscopic colloid is tightly adsorbed on the fin surface of the heat exchanger <NUM>, the above steps are repeated again. It should be noted that the thickness of the above-mentioned hygroscopic colloid <NUM> is approximately the thickness. Due to the limitation of the process or other conditions, it may not achieve a completely uniform overlay effect, or the overlay is non-uniform, which is not limited here.

It is noted that the above spraying method may splash on the surface of the heat exchange tubes <NUM> during the spraying operation. The above immersion method will inevitably cover the hygroscopic colloid <NUM> on the surface of the heat exchange tubes <NUM> during the immersion operation, which is not limited here.

As shown in <FIG>, it is a heat exchange system <NUM> shown in an exemplary embodiment of the present disclosure. The heat exchange system <NUM> at least includes a compressor <NUM>, a first heat exchanger <NUM>, a throttling device <NUM>, a second heat exchanger <NUM>, and a reversing device <NUM>. Optionally, the compressor <NUM> of the heat exchange system <NUM> may be a horizontal compressor or a vertical compressor. Optionally, the throttling device <NUM> may be an expansion valve. In addition, the throttling device <NUM> can also be other components that have the function of reducing pressure and regulating flow of the refrigerant. The present disclosure does not specifically limit the type of the throttling device, which can be selected according to the actual application environment, and will not be repeated here. It should be noted that in some systems, the reversing device <NUM> may not be provided. The heat exchangers <NUM>, <NUM>, and <NUM> described in the present disclosure can be used in the heat exchange system <NUM> as the first heat exchanger <NUM> and/or the second heat exchanger <NUM>. In the heat exchange system <NUM>, the compressor <NUM> compresses the refrigerant, the temperature of the compressed refrigerant increases, and then it enters the first heat exchanger <NUM>. The heat is transferred to the outside through the heat exchange between the first heat exchanger <NUM> and the outside. After that, the refrigerant passing through the throttling device <NUM> becomes a liquid state or a gas-liquid two-phase state. At this time, the temperature of the refrigerant decreases, and then the lower temperature refrigerant flows to the second heat exchanger <NUM>, and after the second heat exchanger <NUM> exchanges heat with the outside, it enters the compressor <NUM> again to realize the refrigerant circulation. When the second heat exchanger <NUM> is used as an outdoor heat exchanger for heat exchange with the air, referring to the above-mentioned embodiment, the heat exchanger is arranged according to actual needs.

Claim 1:
A heat exchanger (<NUM>), comprising a first collecting pipe (<NUM>), a second collecting pipe (<NUM>), a plurality of heat exchange tubes (<NUM>) and at least one fin (<NUM>);
the plurality of heat exchange tubes (<NUM>) respectively connecting with the first collecting pipe (<NUM>) and the second collecting pipe (<NUM>), the heat exchange tube (<NUM>) comprising a pipe wall and a refrigerant flow channel for a refrigerant to circulate, the heat exchange tube (<NUM>) comprising a first end (<NUM>) and a second end (<NUM>) along an extension direction of the heat exchange tube (<NUM>), the refrigerant flow channel extending from the first end (<NUM>) to the second end (<NUM>) along the extension direction of the heat exchange tube (<NUM>) and extending through the heat exchange tube (<NUM>), and the refrigerant flow channel of the heat exchange tube (<NUM>) communicating with an inner cavity of the first collecting pipe (<NUM>) and an inner cavity of the second collecting pipe (<NUM>);
the fin (<NUM>) being at least partially arranged between two adjacent heat exchange tubes (<NUM>); wherein the heat exchanger (<NUM>) further comprises a hygroscopic colloid (<NUM>) adhered to at least part of an outer surface of the fin (<NUM>) and optionally at least part of an outer surface of the heat exchange tube (<NUM>);
characterized in that the fin (<NUM>) extends along a length direction of the heat exchange tube (<NUM>), the outer surface of the fin (<NUM>) comprises a covered area and a non-covered area, the covered area is covered with the hygroscopic colloid (<NUM>), and the non-covered area is not in contact with the hygroscopic colloid (<NUM>).