Patent Application
20240263895
The present disclosure relates to an air conditioner.
In an air conditioner, aluminum or aluminum alloy has recently been used as a material of a refrigerant pipe including a heat transfer tube of a heat exchanger. Aluminum and aluminum alloy are easily corroded. Therefore, in order to suppress the leakage of a refrigerant due to the corrosion, a sacrificial layer (an anti-corrosion layer) including zinc, etc. may be provided on an outer circumference of a heat transfer tube. In this regard, the electric potential of zinc is lower than that of aluminum. In Patent Literature 1, the thickness of an anti-corrosion layer provided at the thinnest part of a heat transfer tube of an indoor unit is larger than that of an anti-corrosion layer provided at the thinnest part of a refrigerant pipe of an outdoor unit in order to suppress the leakage of a refrigerant into a room where the refrigerant easily stagnates.
It has been known that the corrosion of aluminum is accelerated by chlorine. Typically, the salt content of outdoor air tends to be higher than that of room air. Because of this, the heat transfer tube of the outdoor unit may be corroded in Patent Literature 1. In this regard, the heat transfer tube is made of aluminum or aluminum alloy.
An object of the present disclosure is to provide an air conditioner configured to suppress the corrosion of a heat transfer tube of an outdoor unit.
An air conditioner of the present disclosure is configured to condition air by connecting an indoor unit including a first heat exchanger, in which a refrigerant exchanging heat with room air flows, to an outdoor unit including a second heat exchanger in which a refrigerant exchanging heat with outdoor air flows. The first heat exchanger includes a first heat transfer tube made of aluminum or aluminum alloy, and the second heat exchanger includes a second heat transfer tube made of aluminum or aluminum alloy. A first sacrificial layer is formed on an outer circumferential surface of the first heat transfer tube, a second sacrificial layer is formed on an outer circumferential surface of the second heat transfer tube, and the maximum thickness of the second sacrificial layer is larger than the maximum thickness of the first sacrificial layer.
According to the present disclosure, corrosion is suppressed at the second heat transfer tube which is included in the second heat exchanger and through which the outdoor air passes. In this regard, the salt content of the outdoor air is high.
In the above-described air conditioner, the wall thickness of the first heat transfer tube is preferably smaller than the wall thickness of the second heat transfer tube. Because the thickness of the first sacrificial layer is smaller than that of the second sacrificial layer, (i) the necessary thickness of a base material is secured and (ii) the wall thickness of the first heat transfer tube which is a combination of the first sacrificial layer and the base material is small. This improves the efficiency of heat conduction in the first heat exchanger.
In the above-described air conditioner, an inner diameter of the first heat transfer tube is preferably larger than an inner diameter of the second heat transfer tube. This reduces the pressure drop of a refrigerant in the first heat exchanger.
In the above-described air conditioner, an outer diameter of the first heat transfer tube is preferably smaller than an outer diameter of the second heat transfer tube. This suppresses the increase in resistance of air passing through the first heat exchanger.
In the above-described air conditioner, the first sacrificial layer and the second sacrificial layer are preferably made of zinc or alloy including zinc. With this arrangement, a good sacrifice anti-corrosion effect is obtained.
In the above-described air conditioner, the maximum thickness of the first sacrificial layer may be 0.12 mm or more.
In the above-described air conditioner, the maximum thickness of the second sacrificial layer may be 0.17 mm or more.
In the above-described air conditioner, (i) the first heat transfer tube may be formed of: a base material made of aluminum or aluminum alloy; and the first sacrificial layer, (ii) the second heat transfer tube may be formed of another base material made of aluminum or aluminum alloy; and the second sacrificial layer, and (iii) each of the first heat transfer tube and the second heat transfer tube may be formed of a clad material. This suppresses the thickness variation of each sacrificial layer.
In the above-described air conditioner, (i) the first heat transfer tube may be formed of: a base material made of aluminum or aluminum alloy; and the first sacrificial layer, (ii) the second heat transfer tube may be formed of: another base material made of aluminum or aluminum alloy; and the second sacrificial layer, and (iii) each of the first sacrificial layer and the second sacrificial layer may be a diffuse layer made of aluminum-zinc alloy. With this arrangement, each sacrificial layer is relatively easily formed by spraying zinc on a corresponding base material.
The above-described air conditioner may further include an air supply duct configured to allow the outdoor air to flow toward the indoor unit, the first heat exchanger may further include a third heat transfer tube made of aluminum or aluminum alloy, a third sacrificial layer may be formed on an outer circumferential surface of the third heat transfer tube, the maximum thickness of the third sacrificial layer may be larger than the maximum thickness of the first sacrificial layer, and the third heat transfer tube may be closer to an opening of the air supply duct than the first heat transfer tube is to the opening. With this arrangement, the corrosion is suppressed at the third heat transfer tube through which a refrigerant exchanging heat with air flows. The air is blown out from the air supply duct, and has a high salt content.
In the above-described air conditioner, the wall thickness of the first heat transfer tube is preferably smaller than the wall thickness of the third heat transfer tube. Because the thickness of the first sacrificial layer is smaller than that of the third sacrificial layer, (i) the necessary thickness of a base material is secured and (ii) the wall thickness of the first heat transfer tube which is a combination of the first sacrificial layer and the base material is small. This improves the efficiency of heat conduction in an area of the first heat transfer tube of the first heat exchanger.
In the above-described air conditioner, the inner diameter of the first heat transfer tube is preferably larger than an inner diameter of the third heat transfer tube. This reduces the pressure drop of a refrigerant in the area of the heat transfer tube of the first heat exchanger.
In the above-described air conditioner, the outer diameter of the first heat transfer tube is preferably smaller than an outer diameter of the third heat transfer tube. This suppresses the increase in resistance of air passing through the area of the first heat transfer tube of the first heat exchanger.
In the above-described air conditioner, the maximum thickness of the third sacrificial layer may be the same as the maximum thickness of the second sacrificial layer. With this arrangement, the corrosion is suppressed at the third heat transfer tube to the same degree as at the second heat transfer tube.
In the above-described air conditioner, the second sacrificial layer, the third sacrificial layer, and the first sacrificial layer in this order may be the largest, the second largest, and the third largest in maximum thickness. With this arrangement, the higher the salt content of air with which a heat transfer tube exchanges heat is, the larger the thickness of a sacrificial layer formed on this heat transfer tube is.
In the above-described air conditioner, preferably, a coating is formed on a first fin in contact with the outer circumferential surface of the first heat transfer tube, and another coating is formed on a second fin in contact with the outer circumferential surface of the second heat transfer tube. With this arrangement, each fin has the corrosion resistance.
In the above-described air conditioner, the thickness of the another coating formed on the second fin is preferably larger than the thickness of the coating formed on the first fin. This improves the corrosion resistance of the second fin with which the outdoor air makes contact.
The following will describe an air conditioner 1 of First Embodiment of the present disclosure. As shown in
As shown in
The electric expansion valve 25 is connected to the outdoor heat exchanger 24 through a filter 26a, connected to a communication pipe 32 through a filter 26b and a liquid stop valve 27, and connected to one end of an indoor heat exchanger 11 through this communication pipe 32. The four-pass switching valve 22 is connected to a communication pipe 31 through a gas stop valve 28, and connected to the other end of the indoor heat exchanger 11 through this communication pipe 31. Each of these communication pipes 31 and 32 is equivalent to the refrigerant pipe 7 shown in
The indoor heat exchanger 11 connected to the communication pipes 31 and 32 is provided in the indoor unit 2. The indoor heat exchanger 11 is a cross-fin-tube-type heat exchanger panel which includes an indoor piping section and plural fins 11c. The indoor piping section is formed of: plural heat transfer tubes 11a; and a U-bend 11b which is a connecting pipe connecting end portions of the heat transfer tubes 11a to one another. In the present embodiment, each heat transfer tube 11a is a straight pipe. However, each heat transfer tube 11a may be a hairpin tube including two straight pipe portions and a U-shaped portion connecting these two straight pipe portions. Each fin 11c is a flat-plate member, and penetrated by the heat transfer tubes 11a. Each fin 11c is in contact with outer circumferential surfaces of the heat transfer tubes 11a. Each heat transfer tube 11a (see
An indoor fan 12 and an indoor fan motor 13 configured to rotationally drive the indoor fan 12 are provided in the indoor unit 2. The indoor fan 12 is a cross-flow fan which is cylindrical in shape and on a circumferential surface of which a large number of blades are provided. The indoor fan 12 is configured to generate an air flow in a direction intersecting with its rotational axis. The indoor fan 12 is configured to allow room air to be sucked into the indoor unit 2 from a main air inlet 6a and an auxiliary air inlet 6b and to blow out, from an outlet 9, air having exchanged heat with the refrigerant flowing in each heat transfer tube 11a of the indoor heat exchanger 11.
In the present embodiment, the indoor heat exchanger 11 is divided into four parts shown in
The humidification unit 5 is provided on the outdoor refrigerant unit 4. The humidification unit 5 includes a moisture-absorbing rotor, a heater assembly, a humiliation fan, and an absorption fan (all of those are not shown). The humidification unit 5 is configured to take in outdoor air and to generate the heated air or humid air. The generated heated air or humid air is supplied to the indoor unit 2 through the air supply duct 8. In the present embodiment, a part of salt such as a chlorine compound and a chlorine ion included in the outdoor air is removed from the air by a heating process or a humidifying process of the humidification unit 5.
As shown in
In the present embodiment, the heat transfer tubes 11a of the indoor heat exchanger 11 are divided into two groups depending on the thickness of a sacrificial layer formed on the outer circumferential surface of each heat transfer tube 11a. The first group is formed of heat transfer tubes 11a1 included in the front-surface intermediate part Bb, the front-surface lower part Bc, and the back-surface part Bd. The second group is formed of heat transfer tubes 11a2 included in the front-surface upper part Ba. The heat transfer tubes 11a2 of the second group are closer to the opening 8a of the air supply duct 8 than the heat transfer tubes 11a1 of the first group are to the opening 8a. In this regard, whether each heat transfer tube is close to the opening 8a of the air supply duct 8 is determined by comparing parts of heat transfer tubes with one another. A part of each transfer tube (a part of each heat transfer tube, which overlaps the opening 8a in the width direction (i.e., a longitudinal direction of each heat transfer tube) of the indoor unit 2 of the present embodiment) is closer to the opening 8a than the remaining part of each heat transfer tube is to the opening 8a. As described below, the thickness of a sacrificial layer formed on an outer circumferential surface of each heat transfer tube 11a2 of the second group is larger than that of a sacrificial layer formed on an outer circumferential surface of each heat transfer tube 11a1 of the first group.
The following will detail (i) each heat transfer tube 24a of the outdoor heat exchanger 24 and (ii) each heat transfer tube 11a of the indoor heat exchanger 11 (heat transfer tube 11a1 of the first group, heat transfer tube 11a2 of the second group) in the present embodiment.
As shown in
As shown in
As shown in
In the present embodiment, the thickness to of the sacrificial layer 35 of the outdoor heat exchanger 24 is larger than the thickness ti2 of the sacrificial layer 45b of the second group of the indoor heat exchanger 11, and the thickness ti2 of the sacrificial layer 45b is larger than the thickness ti1 of the sacrificial layer 45a of the first group of the indoor heat exchanger 11. That is, the sacrificial layer 35, the sacrificial layer 45b, and the sacrificial layer 45a in this order are the largest, the second largest, and the third largest in maximum thickness (to>ti2>ti1). The thickness of each of the sacrificial layers 35, 45a, and 45b can be measured with use of an electron probe micro analyzer (EPMA), etc. To check the thickness of each of the sacrificial layers 35, 45a, and 45b, each of the heat transfer tubes 24a, 11a1, and 11a2 is cut not at around its end portion to which the U-bend 24b or 11b is brazed but at around its center in the longitudinal direction.
In the present embodiment, the outer diameter Do1 and inner diameter Do2 of the heat transfer tube 24a of the outdoor heat exchanger 24 are the same as the outer diameter Di3 and inner diameter Di4 of the heat transfer tube 11a2 of the second group of the indoor heat exchanger 11 (Do1=Di3, Do2=Di4). With this arrangement, the wall thickness To of the heat transfer tube 24a is the same as the wall thickness Ti2 of the heat transfer tube 11a2 (To=Ti2). The outer diameter Do1 of the heat transfer tube 24a, the outer diameter Di1 of the heat transfer tube 11a1, and the outer diameter Di3 of the heat transfer tube 11a2 are the same as one another (Do1=Di1=Di3). Meanwhile, the inner diameter Di2 of the heat transfer tube 11a1 is larger than each of the inner diameter Do2 of the heat transfer tube 24a of the outdoor heat exchanger 24 and the inner diameter Di4 of the heat transfer tube 11a2 (Do2, Di4<Di2). With this arrangement, the wall thickness Ti1 of the heat transfer tube 11a1 is smaller than each of the wall thickness To of the heat transfer tube 24a of the outdoor heat exchanger 24 and the wall thickness Ti2 of the heat transfer tube 11a2 (Ti1<To, Ti2).
The following will describe the structure of each fin 24c of the outdoor heat exchanger with reference to
The following will describe the structure of each fin 11c of the indoor heat exchanger with reference to
The following will describe the progress of corrosion in the heat transfer tubes 11a and 24a. In an initial state (immediately after manufacture), the entire circumferences of the base materials 34, 44a, and 44b are respectively covered by the sacrificial layers 35, 45a, and 45b. With this arrangement, the corrosion begins not at the base materials 34, 44a, and 44b but at the sacrificial layers 35, 45a, and 45b. When electric potential on each of the surfaces of the sacrificial layers 35, 45a, and 45b is ideally constant, the corrosion progresses so that the thickness of each of the sacrificial layers 35, 45a, and 45b decreases uniformly throughout each of the sacrificial layers 35, 45a, and 45b. Because of this, when the outer circumferential surfaces of the base materials 34, 44a, and 44b are exposed, the sacrificial layers 35, 45a, and 45b no longer exist. Meanwhile, when electric potential is not constant on each of the surfaces of the sacrificial layers 35, 45a, and 45b, each of the sacrificial layers 35, 45a, and 45b is rapidly corroded at its part where electric potential is low. As a result, the outer circumferential surfaces of the base materials 34, 44a, and 44b are partially exposed while the sacrificial layers 35, 45a, and 45b partially remain. In this regard, the electric potential of zinc or alloy including zinc forming the sacrificial layers 35, 45a, and 45b is lower than that of aluminum or aluminum alloy forming the base materials 34, 44a, and 44b. Because of this, the corrosion of the base materials 34, 44a, and 44b does not begin yet, and the corrosion of the sacrificial layers 35, 45a, and 45b further progresses so that the sacrificial layers 35, 45a, and 45b on the base materials 34, 44a, and 44b no longer exist. At this point, pitting corrosion of the base materials 34, 44a, and 44b begins in each of the following cases: the case where electric potential is constant on each of the surfaces of the sacrificial layers 35, 45a, and 45b; and the case where electric potential is not constant on each of the surfaces of the sacrificial layers 35, 45a, and 45b. The pitting corrosion is a phenomenon in which the corrosion progresses typically in a thickness direction of a material.
The progress of the corrosion is described above. Therefore, when (i) the thickness of each of the base materials 34, 44a, and 44b is large and (ii) the thickness of each of the sacrificial layers 35, 45a, and 45b is small, the sacrificial layers 35, 45a, and 45b disappear in a relatively short period of time from the initial state and, thereafter, a through hole is formed on each of the heat transfer tubes 11a and 24a because of the pitting corrosion in a relatively short period of time. Meanwhile, when the thickness of each of the sacrificial layers 35, 45a, and 45b is large, a relatively long period of time is required for the sacrificial layers 35, 45a, and 45b on the base materials 34, 44a, and 44b to disappear. After that, even if a through hole is formed on each of the heat transfer tubes 11a and 24a because of the pitting corrosion in a relatively short period of time, a period of time from the initial state to a state in which a through hole is formed in each of the heat transfer tubes 11a and 24a is long. In the present embodiment, the thickness to of the sacrificial layer 35 formed on the outer circumferential surface of the heat transfer tube 24a of the outdoor heat exchanger 24 is larger than the thickness ti1 of the sacrificial layer 45a formed on the outer circumferential surface of the heat transfer tube 11a1 of the indoor heat exchanger 11. With this arrangement, the corrosion is suppressed at the following tubes: the heat transfer tube 11a1 of the indoor heat exchanger 11 in which a refrigerant exchanging heat with the room air flows; and the heat transfer tube 24a of the outdoor heat exchanger 24 in which a refrigerant exchanging heat with the outdoor air flows. The salt content of the room air is low, and the salt content of the outdoor air is high. Furthermore, because the sacrificial layer 45a does not need to be thick, an amount of use of materials is reduced. As a result, low cost is achieved.
The thickness ti2 of the sacrificial layer 45b formed on the outer circumferential surface of the heat transfer tube 11a2 of the second group of the indoor heat exchanger 11 is larger than the thickness ti1 of the sacrificial layer 45a formed on the outer circumferential surface of the heat transfer tube 11a1 of the first group of the indoor heat exchanger 11. With this arrangement, the corrosion is suppressed at the following tubes: the heat transfer tube 11a1 of the indoor heat exchanger 11 in which a refrigerant exchanging heat with the room air flows; and the heat transfer tube 11a2 of the indoor heat exchanger 11 in which a refrigerant exchanging heat with the heated air or humid air flows. In this regard, the salt content of the room air is low, and the salt content of each of the heated air and the humid air is lower than that of the outdoor air and higher than that of the room air. Furthermore, because the sacrificial layer 45a does not need to be thick, an amount of use of materials is reduced. As a result, the low cost is achieved. In addition to that, because the thickness ti2 of the sacrificial layer 45b is smaller than the thickness to of the sacrificial layer 35, an amount of use of materials is reduced. As a result, the low cost is achieved.
The thickness ti1 of the sacrificial layer 45a of the indoor heat exchanger 11 is relatively small so that the ratio of thickness of the base material 44a to that of the sacrificial layer 45a is large in the heat transfer tube 11a1. This makes it easy to maintain the outer diameter Di1 of the heat transfer tube 11a1 and to suppress the decrease of the inner diameter Di2 of the heat transfer tube 11a1. By suppressing the decrease of the inner diameter Di2 of the heat transfer tube 1a1, (i) the increase in pressure drop of a refrigerant passing through the heat transfer tube 11a1 of the indoor heat exchanger 11 and (ii) the decrease in capacity of the indoor heat exchanger 11 are suppressed. To put it differently, the thickness ti1 of the sacrificial layer 45a of the indoor heat exchanger 11 is relatively small so that the ratio of thickness of the base material 44a to that of the sacrificial layer 45a is large in the heat transfer tube 11a1. This makes it possible to maintain the inner diameter Di2 of the heat transfer tube 11a1 and to suppress the increase of the outer diameter Di1 of the heat transfer tube 11a1. By suppressing the increase of the outer diameter Di1 of the heat transfer tube 11a1, (i) the structure of the fin 11c does not need to be greatly changed and (ii) air resistance is not increased in the indoor heat exchanger 11.
In the present embodiment, the thickness ti1 of the sacrificial layer 45a is smaller than each of the thickness to of the sacrificial layer 35 and the thickness ti2 of the sacrificial layer 45b as described above. With this arrangement, the necessary thickness of the base material 44a is secured, and the wall thickness Ti1 of the heat transfer tube 11a1 which is a combination of the sacrificial layer 45a and the base material 44a is smaller than each of the wall thickness To of the heat transfer tube 24a and the wall thickness Ti2 of the heat transfer tube 11a2. This improves the efficiency of heat conduction in the heat transfer tube 11a1 of the indoor heat exchanger 11.
In the present embodiment, the inner diameter Di2 of the heat transfer tube 11a1 of the first group of the indoor heat exchanger 11 is larger the inner diameter Do2 of the heat transfer tube 24a of the outdoor heat exchanger 24. This reduces the pressure drop of a refrigerant in the indoor heat exchanger 11. Furthermore, this makes the surface area of the inner circumferential surface of the heat transfer tube 11a1 relatively large. It is therefore possible to suppress the decrease in capacity of the indoor heat exchanger 11. In the present embodiment, the inner diameter Di2 of the heat transfer tube 11a1 of the first group of the indoor heat exchanger 11 is larger than the inner diameter Di4 of the heat transfer tube 11a2 of the second group of the indoor heat exchanger 11. This reduces the pressure drop of a refrigerant in the heat transfer tube 11a1 of the first group of the indoor heat exchanger 11. Furthermore, this makes the surface area of the inner circumferential surface of the heat transfer tube 11a1 relatively large. It is therefore possible to suppress the decrease in capacity of the heat transfer tube 11a1 of the first group of the indoor heat exchanger 11.
In the present embodiment, these sacrificial layers 35, 45b, and 45a in this order are the largest, the second largest, and the third largest in thickness (to>ti2>ti1). This order reflects the salt content of air passing through the surface of each sacrificial layer. That is, because the outdoor air whose salt content is high passes through the surface of the sacrificial layer 35, the sacrificial layer 35 is thickest. Furthermore, because the outdoor air whose salt content is low passes through the surface of the sacrificial layer 45a, the sacrificial layer 45a is thinnest. In addition to that, because the heated air or humid air which is lower in salt content than the outdoor air and higher in salt content than the room air passes through the surface of the sacrificial layer 45b, the sacrificial layer 45b is thinner than the sacrificial layer 35 and thicker than the sacrificial layer 45a. The thicknesses of the sacrificial layers 35, 45a, and 45b of three types are adjusted as described above. This suppresses the occurrence of a large difference between the heat transfer tubes 11a1, 11a2, and 24a of three types in terms of a period of time from the initial state to a state in which a through hole is formed.
The outer diameter Do1 of the heat transfer tube 24a, the outer diameter Di1 of the heat transfer tube 11a1, and the outer diameter Di3 of the heat transfer tube 11a2 are the same as one another (Do1=Di1=Di3). With this arrangement, the fins 11c and 24c are easily manufactured.
In the present embodiment, each of the sacrificial layers 35, 45a, and 45b is made of zinc or alloy including zinc, and each of the base materials is made of aluminum or aluminum alloy. In this regard, the electric potential of each of zinc and alloy including zinc is lower than that of each of aluminum and aluminum alloy. With this arrangement, a good sacrifice anti-corrosion effect is obtained. Each sacrificial layer may be made of metal which is neither zinc nor alloy including zinc, as long as the electric potential of the metal is lower than that of each of aluminum and aluminum alloy making a base material.
In the present embodiment, the heat transfer tube 24a of the outdoor heat exchanger 24 and the heat transfer tube 11a of the indoor heat exchanger 11 are formed of clad materials in which the base materials 34, 44a, and 44b and the sacrificial layers 35, 45a, and 45b are diffusion bonded. This suppresses the thickness variation of each of the sacrificial layers 35, 45a, and 45b. When the thickness variation of each sacrificial layer is significantly large, an exposed part of the outer circumferential surface of each of the base materials 34, 44a, and 44b may be so far from the remaining part of each of the sacrificial layers 35, 45a, and 45b that the exposed part of the outer circumferential surface of each of the base materials 34, 44a, and 44b has a position where the anti-corrosion effect is not expected. By using the clad materials, occurrence of this problem is suppressed.
In the present embodiment, coatings are formed on the fin 24c of the outdoor heat exchanger 24 and the fin 11c of the outdoor heat exchanger 11. With this arrangement, the fin 24c has the corrosion resistance. The thickness of a combination of the hydrophobic coating 53 and hydrophilic coating 54 of the fin 24c is larger than that of the hydrophilic coating 57 of the fin 11c. This improves the corrosion resistance of the fin 24c with which the outdoor air makes contact. In this regard, this improvement does not depend on the number of coatings formed on the fin 24c and the fin 11c. The number of coatings formed on the fin 24c may be smaller than or the same as that of coatings formed on the fin 11c.
The following will describe Second Embodiment with reference to
As shown in
As shown in
In the present embodiment, a sacrificial layer 35, the sacrificial layer 75b, and the sacrificial layer 75a in this order are the largest, the second largest, and the third largest in maximum thickness (to>ti4>ti3).
In the present embodiment, an outer diameter Do1 and inner diameter Do2 of each heat transfer tube 24a of the outdoor heat exchanger 24 are the same as the outer diameter Di7 and inner diameter Di8 of the heat transfer tube 61a2 of the second group of the indoor heat exchanger (Do1=Di7, Do2=Di8). With this arrangement, the wall thickness To of the heat transfer tube 24a is the same as the wall thickness Ti4 of the heat transfer tube 61a2 (To=Ti4). The inner diameter Do2 of the heat transfer tube 24a, the inner diameter Di6 of the heat transfer tube 61a1, and the inner diameter Di8 of the heat transfer tube 61a2 are the same as one another (Do2=Di6=Di8). Meanwhile, the outer diameter Di5 of the heat transfer tube 61a1 is smaller than each of the outer diameter Do1 of the heat transfer tube 24a and the outer diameter Di7 of the heat transfer tube 61a2 (Di5<Do1, Di7). With this arrangement, the wall thickness Ti3 of the heat transfer tube 61a1 is smaller than each of the wall thickness To of the heat transfer tube 24a of the outdoor heat exchanger 24 and the wall thickness Ti4 of the heat transfer tube 61a2 (Ti3<To, Ti4).
In the present embodiment, the thickness to of the sacrificial layer 35 formed on an outer circumferential surface of the heat transfer tube 24a of the outdoor heat exchanger 24 is larger than the thickness ti3 of the sacrificial layer 75a formed on the outer circumferential surface of the heat transfer tube 61a1 of the indoor heat exchanger. With this arrangement, corrosion is suppressed at the following tubes: the heat transfer tube 61a1 of the indoor heat exchanger in which a refrigerant exchanging heat with room air flows; and the heat transfer tube 24a of the outdoor heat exchanger 24 in which a refrigerant exchanging heat with outdoor air flows. The salt content of the room air is low, and the salt content of the outdoor air is high. Furthermore, because the sacrificial layer 75a does not need to be thick, an amount of use of materials is reduced. As a result, low cost is achieved. The thickness ti4 of the sacrificial layer 75b is larger than the thickness ti3 of the sacrificial layer 75a. With this arrangement, the corrosion is suppressed at the heat transfer tubes 61a1 and 61a2.
In the present embodiment, the thickness ti3 of the sacrificial layer 75a is smaller than each of the thickness to of the sacrificial layer 35 and the thickness ti4 of the sacrificial layer 75b as described above. With this arrangement, the necessary thickness of the base material 74a is secured, and the wall thickness Ti3 of the heat transfer tube 61a1 which is a combination of the sacrificial layer 75a and the base material 74a is smaller than each of the wall thickness To of the heat transfer tube 24a and the wall thickness Ti4 of the heat transfer tube 61a2. This improves the efficiency of heat conduction in the heat transfer tube 61a1 of the indoor heat exchanger.
In the present embodiment, the outer diameter Di5 of the heat transfer tube 61a1 of the first group is smaller than each of the outer diameter Do1 of the heat transfer tube 24a of the outdoor heat exchanger 24 and the outer diameter Di7 of the heat transfer tube 61a2 of the second group. This suppresses the increase in resistance of air passing through the indoor heat exchanger.
The following will describe Third Embodiment with reference to
As shown in
As shown in
In the present embodiment, a sacrificial layer 35, the sacrificial layer 95b, and the sacrificial layer 95a in this order are the largest, the second largest, and the third largest in maximum thickness (to>ti6>ti5).
In the present embodiment, the outer diameter Di9 and inner diameter Di10 of the heat transfer tube 81a1 of the first group of the indoor heat exchanger are the same as the outer diameter Di11 and inner diameter Di12 of the heat transfer tube 81a2 of the second group of the indoor heat exchanger (Di9=Di11, Di10=Di12). Each of the outer diameter Di9 of the heat transfer tube 81a1 and the outer diameter Di11 of the heat transfer tube 81a2 is smaller than an outer diameter Do1 of each heat transfer tube 24a of the outdoor heat exchanger 24 (Di9, Di11<Do1). Each of the inner diameter Di10 of the heat transfer tube 81a1 and the inner diameter Di12 of the heat transfer tube 81a2 is smaller than an inner diameter Do2 of the heat transfer tube 24a of the outdoor heat exchanger 24 (Di10, Di12<Do2). Each of the wall thickness Ti5 of the heat transfer tube 81a1 and the wall thickness Ti6 of the heat transfer tube 81a2 is smaller than the wall thickness To of the heat transfer tube 24a (Ti5, Ti6<To).
In the present embodiment, the thickness to of the sacrificial layer 35 formed on an outer circumferential surface of the heat transfer tube 24a of the outdoor heat exchanger 24 is larger than the thickness ti5 of the sacrificial layer 95a formed on the outer circumferential surface of the heat transfer tube 81a1 of the indoor heat exchanger. With this arrangement, corrosion is suppressed at the following tubes: the heat transfer tube 81a1 of the indoor heat exchanger in which a refrigerant exchanging with room air flows; and the heat transfer tube 24a of the outdoor heat exchanger 24 in which a refrigerant exchanging heat with outdoor air flows. The salt content of the room air is low, and the salt content of the outdoor air is high. Furthermore, because the sacrificial layer 95a does not need to be thick, an amount of use of materials is reduced. As a result, low cost is achieved. The thickness ti6 of the sacrificial layer 95b is larger than the thickness ti5 of the sacrificial layer 95a. With this arrangement, the corrosion is suppressed at the heat transfer tubes 81a1 and 81a2.
In the present embodiment, each of the thickness ti5 of the sacrificial layer 95a and the thickness ti6 of the sacrificial layer 95b is smaller than the thickness to of the sacrificial layer 35 as described above. With this arrangement, the necessary thicknesses of the base materials 94a and 94b are secured, and each of the following wall thicknesses is smaller than the wall thickness To of the heat transfer tube 24a: the wall thickness Ti5 of the heat transfer tube 81a1 which is a combination of the sacrificial layer 95a and the base material 94a; and the wall thickness Ti6 of the heat transfer tube 81a2 which is a combination of the sacrificial layer 95b and the base material 94b. This improves the efficiency of heat conduction in the heat transfer tubes 81a1 and 81a2 of the indoor heat exchanger.
In the present embodiment, each of the outer diameter Di5 of the heat transfer tube 61a1 the first group and the outer diameter Di7 of the heat transfer tube 61a2 of the second group is smaller the outer diameter Do1 of the heat transfer tube 24a of the outdoor heat exchanger 24. This suppresses the increase in resistance of air passing through the indoor heat exchanger as compared to Second Embodiment.
The following will describe Fourth Embodiment with reference to
In the present embodiment, each heat transfer tube of an outdoor heat exchanger is the same as that in First Embodiment shown in
In the present embodiment, the thickness to of the sacrificial layer 35 of the outdoor heat exchanger 24 is the same as the thickness ti7 of the sacrificial layer 115b of the second group of the indoor heat exchanger. Each of these thicknesses to and ti7 is larger than the thickness ti1 of the sacrificial layer 45a of the first group of the indoor heat exchanger (to=ti7>ti1). In the present embodiment, because the salt content of air blown out from the opening 8a of the air supply duct 8 is the same as that of the outdoor air, the thickness ti7 of the sacrificial layer 115b of the second group is the same as the thickness to of the sacrificial layer 35 of the outdoor heat exchanger 24 as described above. With this arrangement, corrosion is suppressed at the heat transfer tube 101a2 of the second group to the same degree as at the heat transfer tube 24a of the outdoor heat exchanger 24.
The following will describe Fifth Embodiment with reference to
As shown in
Preferably, zinc is uniformly sprayed on a base material throughout the circumference of the base material so as to form a sacrificial layer the thickness of which is uniform. However, because of the limitation in the manufacture, the thickness of a sacrificial layer actually formed tends to vary in a circumferential direction of a base material. In the heat transfer tube 121a of the present embodiment, as shown in
The maximum thickness ti8 of the sacrificial layer 132 formed on the outer circumferential surface of the heat transfer tube 121a of the indoor heat exchanger is smaller than the maximum thickness to of a sacrificial layer 35 formed on an outer circumferential surface of each heat transfer tube 24a of the outdoor heat exchanger 2. In this regard, the sacrificial layer formed on the outer circumferential surface of the heat transfer tube of the outdoor heat exchanger 2 may be formed by spraying. In this case, the maximum thickness of the sacrificial layer formed on the outer circumferential surface of the heat transfer tube of the outdoor heat exchanger is preferably 0.17 mm or more.
In the present embodiment, an outer diameter Do1 of the heat transfer tube 24a of the outdoor heat exchanger 24 is the same as the outer diameter Di15 of the heat transfer tube 121a of the indoor heat exchanger (Do1=Di15). Meanwhile, the inner diameter Di16 of the heat transfer tube 121a is larger than an inner diameter Do2 of the heat transfer tube 24a of the outdoor heat exchanger 24 (Do2<Di16). With this arrangement, the wall thickness Ti8 of the heat transfer tube 121a is smaller than the wall thickness To of the heat transfer tube 24a of the outdoor heat exchanger 24 (Ti8<To).
In the present embodiment, the sacrificial layer 132 is relatively easily formed by spraying zinc on the base material 131. Effects which are the same as those of the heat transfer tube 11a1 of First Embodiment described above are obtained.
In each of First to Fourth Embodiments described above, the heat transfer tubes of the first group or second group belong to each of the four parts (the front-surface upper part Ba, the front-surface intermediate part Bb, the front-surface lower part Bc, and the back-surface part Bd) of the indoor heat exchanger 11. That is, heat transfer tubes of two types between which the thickness of a sacrificial layer is different are not included in the same part. In a modification, however, the heat transfer tubes of the two types between which the thickness of the sacrificial layer is different may be included in each of the four parts by using the heat transfer tubes of the second group as heat transfer tubes on one line which is closer to the opening 8a of the air supply duct 8 and using the heat transfer tubes of the first group as heat transfer tubes on the other line which is further from the opening 8a than the heat transfer tubes of the second group. In this regard, the thickness of the sacrificial layer of each heat transfer tube of the second group is large while that of the first group is small.
In each of Embodiments described above, the outer diameter and inner diameter of each heat transfer tube may be suitably changed. For example, in First Embodiment, the outer diameter and inner diameter of the heat transfer tube 24a (see
In First Embodiment, the inner diameter Di2 of the heat transfer tube 11a1 of the first group is larger than the inner diameter Do2 of the heat transfer tube 24a of the outdoor heat exchanger 24, and the outer diameter Di1 of the heat transfer tube 11a1 of the first group is the same as the outer diameter Do1 of the heat transfer tube 24a of the outdoor heat exchanger 24. In Second Embodiment, the outer diameter Di5 of the heat transfer tube 61a1 of the first group is smaller than the outer diameter Do1 of the heat transfer tube 24a of the outdoor heat exchanger 24, and the inner diameter Di6 of the heat transfer tube 61a1 of the first group is the same as the inner diameter Do2 of the heat transfer tube 24a of the outdoor heat exchanger 24. For another example, (i) the inner diameter of each heat transfer tube of the first group may be larger than that of each heat transfer tube of the outdoor heat exchanger and (ii) the outer diameter of the heat transfer tube of the first group may be smaller than the outer diameter Do1 of the heat transfer tube of the outdoor heat exchanger. Alternatively, (i) the inner diameter of the heat transfer tube of the first group may be larger than that of each heat transfer tube of the second group and (ii) the outer diameter of the heat transfer tube of the first group may be smaller than that of the heat transfer tube of the second group.
The air conditioner of each of First to Fourth Embodiments described above includes the air supply duct configured to allow the outdoor air to flow toward the indoor unit. However, the air conditioner of each of these Embodiments may not include the air supply duct. In this case, all heat transfer tubes of the indoor heat exchanger may be the same as the heat transfer tubes of the first groups in each of these Embodiments described above. In each of First to Third Embodiments described above, the humidification unit 5 includes the moisture-absorbing rotor, the heater assembly, the humiliation fan, and the absorption fan. However, the humidification unit 5 may be an air supply unit used for supplying the outdoor air to the room. The air supply unit includes an air supply fan. The humidification unit and the air supply unit may be provided on the refrigerant unit 4 or may be provided separately from the outdoor unit.
The thickness of the sacrificial layer formed on each heat transfer tube of the first group of the indoor heat exchanger may be zero. The present disclosure is applicable to a microchannel heat exchanger including a heat transfer tube made of aluminum or aluminum alloy. The present disclosure is also applicable to an outdoor air processor configured to condition and supply outdoor air to a room.
In another perspective, the air conditioner of the present disclosure is configured to condition air by connecting the following units to each other: the indoor unit including a first heat exchanger in which a refrigerant exchanging heat with the room air flows; the outdoor unit including a second heat exchanger in which a refrigerant exchanging heat with the outdoor air flows. The first heat exchanger includes a first heat transfer tube, and the second heat exchanger includes a second heat transfer tube. Furthermore, a coating is formed on a first fin in contact with an outer circumferential surface of the first heat transfer tube, and a coating is formed on a second fin in contact with an outer circumferential surface of the second heat transfer tube. A first sacrificial layer and a second sacrificial layer may not be formed on the first heat transfer tube and the second heat transfer tube. The thickness of the coating formed on the second fin is preferably larger than that of the coating formed on the first fin. The first fin and the second fin are preferably made of aluminum or aluminum alloy. The first sacrificial layer and the second sacrificial layer are preferably formed on the first heat transfer tube and the second heat transfer tube.
In each of Embodiments described above, the thickness of the sacrificial layer formed on the outer circumferential surface of the heat transfer tube of each heat exchanger may vary depending on a position in the heat exchanger. In the heat exchanger, for example, the thickness of one part of the sacrificial layer is preferably larger than that of another part of the sacrificial layer. In this regard, the air speed is high at one part of the sacrificial layer and low at another part thereof. To an area where the air speed is high, the large number of chloride ions accelerating the corrosion adheres so that the corrosion easily progresses. The thickness of the sacrificial layer is therefore arranged to vary depending on the position in the heat exchanger as described above so that the corrosion of the heat transfer tube is suppressed in accordance with the distribution of air speed. This arrangement to vary the thickness of the sacrificial layer in accordance with the distribution of air speed is applicable to both of the indoor heat exchanger and the outdoor heat exchanger. Furthermore, this arrangement is applicable to a case where, in each of First to Fourth Embodiments, (i) the air supply duct 8 is not provided and (ii) only the heat transfer tube of the first group is formed in the indoor heat exchanger. In another perspective, the air conditioner of the present disclosure includes a heat exchanger, the heat exchanger includes a first heat transfer tube and a second heat transfer tube which are made of aluminum or aluminum alloy, the air speed at the first heat transfer tube is lower than that at the second heat transfer tube, a first sacrificial layer is formed on an outer circumferential surface of the first heat transfer tube, a second sacrificial layer is formed on an outer circumferential surface of the second heat transfer tube, and the maximum thickness of the second sacrificial layer is larger than that of the first sacrificial layer.
Although Embodiments have been described above, it will be understood that various changes in form and details are possible as long as the changes do not depart from the spirit and scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-161628 | Sep 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/021142 | 5/23/2022 | WO |
