JP3761262B2 - Finned heat exchanger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a finned heat exchanger that transfers heat between a refrigerant such as an air conditioner, a refrigeration apparatus, and an automobile apparatus and a fluid such as air.
[0002]
[Prior art]
In recent years, heat exchangers with fins have been required to be compact in terms of equipment design, and slits and louvers are provided on the fin surface, grooves and cavities are provided on the inner surface of the heat transfer tube, and the heat transfer tube has a small diameter. The device has been greatly reduced in size and increased in efficiency. As a conventional heat exchanger with fins, a shape disclosed in Japanese Patent Application Laid-Open No. 61-252494 is common.
[0003]
The conventional finned heat exchanger will be described below with reference to the drawings.
FIG. 9 is a perspective view of a conventional finned heat exchanger. In FIG. 9, 1 is a fin arranged in parallel at a constant interval, and 2 is a heat transfer tube penetrating the fin 1 and provided in two rows in the airflow direction. 10 is a partially enlarged view of the vertical cross section of FIG. 9, and FIG. 11 is a cross-sectional view taken along line AA of FIG. In FIG. 10 and FIG. 11, reference numeral 3 denotes a slit provided on the surface of the fin 1, which is provided on both surfaces by cutting and raising the fin 1 to a substantially constant width.
[0004]
About the heat exchanger with a fin comprised as mentioned above, the operation | movement is demonstrated below.
[0005]
The airflow flowing between the fins 1 and the refrigerant flowing inside the heat transfer tubes 2 indirectly perform heat exchange via the fins 1 and the heat transfer tubes 2. At this time, since the slit 3 is provided on the surface of the fin 1, the temperature boundary layer of the airflow generated on the surface of the fin 1 is updated by the slit 3, and heat transfer between the fin 1 and the airflow is promoted.
[0006]
[Problems to be solved by the invention]
However, when the conventional heat exchanger with fins is used under such a condition that the evaporating temperature of the refrigerant becomes below the freezing point, such as an outdoor unit in a heating operation of a heat pump air conditioner or an evaporator of a refrigeration apparatus, and the surface of the fin 1 is frosted. The frost is concentrated on the front edge of the slit 3 where the thermal conductivity between the airflow and the fin 1 is extremely high. In particular, in the front row in the airflow direction, the amount of frost formation is large due to the large temperature difference between the airflow and the refrigerant, and the leading edge of the slit 3 is blocked by frost formation immediately after the start of operation, and flows into the heat exchanger with fins. There was a drawback that the amount of heat exchanged abruptly decreased due to a decrease in the amount of air flow. As a result, the number of defrosting operations is increased, and heat pump air conditioners have the disadvantage that the comfort is lowered, and the refrigeration equipment has a lowered refrigeration quality such as food freshness.
[0007]
Further, as a technique for suppressing frost formation, there is a method of performing a water-repellent surface treatment on the surface of the fin, and it is said that the time until clogging by frost formation can be extended considerably. However, in this method, under conditions where the temperature of the refrigerant is relatively high and water droplets condense on the surface of the fin, the water resistance bridges and remains in the slit portion, so the ventilation resistance increases, so the air volume is reduced and heat is reduced. In addition to a decrease in the amount of exchange, there was a drawback in that water droplets scattered on the back of the heat exchanger.
[0008]
The present invention solves the conventional problem, and aims to provide a heat exchanger with fins that suppresses a rapid decrease in the amount of heat exchange during frost formation while promoting heat transfer between the fins and the airflow. To do.
[0011]
[Means for Solving the Problems]
  To achieve this goalThe present invention is composed of fins that are arranged in parallel at regular intervals, a gas flows between them, and a plurality of heat transfer tubes that pass through the fins and a fluid flows inside, and are provided with a plurality of slits on the surface of the fins. Fins and flat fins arranged alternately.
[0012]
As a result, the air flow can flow in the vicinity of the adjacent flat fin even if the slit is closed due to frosting while promoting the heat transfer between the air flow and the fin by the slit as in the conventional invention. The blockage of the flow path as a whole of the exchanger can be delayed, and a rapid decrease in the heat exchange amount due to a decrease in the air volume can be suppressed.
[0013]
Furthermore, the present invention is composed of fins arranged in parallel at regular intervals, in which a gas flows between each other, and a plurality of heat transfer tubes through which the fluid flows, and a plurality of slits are formed on the surface of the fin. The provided fins and flat fins are alternately arranged, and the surface of the fin provided with slits is subjected to a water-repellent surface treatment, and the surface of the flat fin is subjected to a hydrophilic surface treatment.
[0014]
As a result, while the heat transfer between the airflow and the fin is promoted by the slit as in the conventional invention, the formation and growth of frost is strongly delayed by the water-repellent surface treatment in the fin provided with the slit, and the heat in the slit is increased. Reduced transmission rate and blockage, greatly reduced heat exchange rate due to reduced airflow, and hydrophilic surface adjacent to water droplets bridging into slits at the time of condensation, which is a problem of water-repellent surface treatment Water can be drained through the treated flat fins, and it is possible to suppress an increase in ventilation resistance at the time of condensation and to prevent water splashing to the back of the heat exchanger.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
  Claims of the invention1The invention described inA fin that is arranged in parallel at regular intervals and includes a fin through which a gas flows, and a plurality of heat transfer tubes that pass through the fin and through which the fluid flows, and in which a plurality of slits are provided on the surface of the fin And flat fins without slits,The surface of the fin provided with the slit is subjected to a water-repellent surface treatment, and the surface of the flat fin is subjected to a hydrophilic surface treatment.While the temperature boundary layer generated on the surface of the fin is updated by the slit to promote heat transfer between the airflow and the fin, the airflow can flow in the vicinity of the adjacent flat fin even if the slit is closed due to frost formation. Therefore, the blockage of the flow path as a whole of the heat exchanger can be delayed, and a rapid decrease in the heat exchange amount due to a decrease in the air volume can be suppressed,For fins with slits, the formation and growth of frost is strongly delayed by water-repellent surface treatment to reduce the heat transfer rate and blockage in the slits, greatly reducing the amount of heat exchange due to the reduction in airflow. When condensation is a problem with water-repellent surface treatment, water droplets bridging the slits can be drained through adjacent flat fins with hydrophilic surface treatment, increasing ventilation resistance and heat exchange during condensation. It has the effect that water splash to the back of the vessel can be suppressed.
[0018]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0019]
(Example 1)
FIG. 1 is a partially enlarged view of a longitudinal sectional view of a finned heat exchanger according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along the line BB of FIG. 1 and 2, reference numeral 4 denotes fins arranged in parallel at regular intervals. Reference numeral 2 denotes a plurality of heat transfer tubes that pass through the fins 4 and in which a fluid flows, and the heat transfer tubes 2 have the same configuration as the conventional one. 5 is a slit provided by cutting and raising the surface of the fin 4, and in the front row with respect to the air flow direction, flat surfaces 6 without the slits 5 between the heat transfer tubes 2 remain in every other step in the step direction perpendicular to the air flow. In the rear row, all the stages are provided.
[0020]
About the heat exchanger with a fin comprised as mentioned above, the operation | movement is demonstrated below.
[0021]
The airflow flowing between the fins 4 and the refrigerant flowing inside the heat transfer tubes 2 exchange heat indirectly via the fins 4 and the heat transfer tubes 2. At this time, since the slit 5 is provided on the surface of the fin 4, the temperature boundary layer of the airflow generated on the surface of the fin 4 is updated by the slit 5 and heat transfer between the fin 4 and the airflow is promoted. Further, when the heat pump air conditioner is used under the condition that the refrigerant evaporating temperature is below the freezing point and the surface of the fin 4 is frosted, such as an outdoor unit during the heating operation of the heat pump air conditioner, the fins 4 are formed by the slits 5 as described above. Even if the front row slits 5 having a large heat exchange amount are closed due to frost formation, the temperature boundary layer generated on the surface of the steel plate is updated to promote heat transfer between the airflow and the fins 4. Since the air flow can flow through the flat surface 6, the blockage of the flow path as the entire front row of the heat exchanger can be delayed, and a rapid decrease in the heat exchange amount due to a decrease in the air amount can be suppressed.
[0022]
As described above, the heat exchanger with fins of the present embodiment is arranged in parallel at regular intervals, the fins 4 through which gas flows, and the plurality of heat transfer tubes 2 through which the fluid flows through the fins 4. A plurality of continuous slits 5 and a flat surface 6 without slits 5 are arranged in a step direction perpendicular to the airflow between the heat transfer tubes 2 on the surface of the fin 4 positioned in the front row with respect to the airflow direction. By alternately providing the slits 5, heat transfer between the airflow and the fins 4 is promoted by the slits 5, and even if the slits 5 in the front row having a large heat exchange amount are closed due to frost formation, the slits 5 are provided every other step in the front row. Since the air flow can flow through the flat surface 6, the blockage of the flow path as the entire front row of the heat exchanger can be delayed, and a rapid decrease in the heat exchange amount due to a decrease in the air amount can be suppressed.
[0023]
(Example 2)
3 and 4 are partially enlarged views of the longitudinal sectional view of the finned heat exchanger according to the second embodiment of the present invention, and FIG. 5 is a CC longitudinal sectional view of FIGS. 3 to 5, reference numerals 7a and 7b denote fins arranged in parallel at regular intervals. Reference numeral 2 denotes a plurality of heat transfer tubes that pass through the fins 7a and 7b and in which a fluid flows, and the heat transfer tube 2 has the same configuration as the conventional one. Reference numeral 8 denotes a plurality of slits provided on the surface of the fin 7a. The fins 7a having the slits 8 and the flat fins 7b having no slits 8 are alternately arranged.
[0024]
About the heat exchanger with a fin comprised as mentioned above, the operation | movement is demonstrated below.
[0025]
The airflow flowing between the fins 7 a and 7 b and the refrigerant flowing inside the heat transfer tube 2 indirectly exchange heat through the fins 7 a and 7 b and the heat transfer tube 2. At this time, since the slit 8 is provided on the surface of the fin 7a, the temperature boundary layer of the airflow generated on the surface of the fin 7a is updated by the slit 8, and heat transfer between the fin 7a and the airflow is promoted. In addition, when the heat pump air conditioner is used under the condition that the refrigerant evaporating temperature is below the freezing point and the surfaces of the fins 7a and 7b are frosted, such as an outdoor unit during heating operation of the heat pump air conditioner, the slit 8 is used as described above. While the temperature boundary layer generated on the surface of the fin 7a is updated to promote heat transfer between the airflow and the fin 7a, the airflow flows in the vicinity of the adjacent flat fin 7b even if the slit 8 is closed due to frost formation. Therefore, the blockage of the flow path as a whole of the heat exchanger can be delayed, and the rapid decrease in the heat exchange amount due to the decrease in the air volume can be suppressed.
[0026]
As described above, the finned heat exchanger of the present embodiment is arranged in parallel at regular intervals, and the fluid flows through the fins 7a and 7b through which gas flows between the fins 7a and 7b. The temperature boundary layer generated on the surface of the fin 7a by the slit 8 is updated by alternately arranging the fins 7a and the flat fins 7b, each of which is composed of the plurality of heat transfer tubes 2 and provided with a plurality of slits 8 on the surface. Since the airflow can flow in the vicinity of the adjacent flat fins 7b even if the slit 8 is blocked by frosting while promoting heat transfer between the airflow and the fins 7a, the flow path as a whole of the heat exchanger Can be delayed, and a rapid decrease in the amount of heat exchange due to a decrease in the air volume can be suppressed.
[0027]
(Example 3)
6 and 7 are partially enlarged views of a longitudinal section of a finned heat exchanger according to a third embodiment of the present invention, and FIG. 8 is a DD sectional view of FIGS. 6 and 7. 6 to 8, 9a and 9b are fins arranged in parallel at regular intervals. Reference numeral 2 denotes a plurality of heat transfer tubes that pass through the fins 9a and 9b and in which a fluid flows, and the heat transfer tube 2 has the same configuration as the conventional one. Reference numeral 10 denotes a plurality of slits cut and raised on the surface of the fin 9a. The fins 9a provided with the slits 10 and the flat fins 9b without the slits 10 are alternately arranged. Further, a water repellent surface treatment 11 is applied to the surface of the slit 10 of the fin 9a, and a hydrophilic surface treatment 12 is applied to the surface of the flat fin 9b.
[0028]
About the heat exchanger with a fin comprised as mentioned above, the operation | movement is demonstrated below.
[0029]
The airflow flowing between the fins 9 a and 9 b and the refrigerant flowing inside the heat transfer tube 2 indirectly exchange heat through the fins 9 a and 9 b and the heat transfer tube 2. At this time, since the slit 10 is provided on the surface of the fin 9a, the temperature boundary layer of the airflow generated on the surface of the fin 9a is updated by the slit 10, and heat transfer between the fin 9a and the airflow is promoted. In addition, when the heat pump air conditioner is used under the condition that the refrigerant evaporating temperature is below the freezing point and the surfaces of the fins 9a and 9b are frosted, such as an outdoor unit during heating operation of the heat pump air conditioner, the slit 10 is used as described above. While the temperature boundary layer generated on the surface of the fin 9a is updated to promote heat transfer between the airflow and the fin 9a, the formation of frost and the growth of the fin 9a having the slit 10 are strongly delayed by the water-repellent surface treatment 11. As a result, it is possible to delay the decrease and blockage of the heat transfer coefficient of the slit 10 and greatly suppress the decrease of the heat exchange amount due to the decrease of the air volume, and to bridge the slit 10 at the time of dew condensation, which is a problem of the water repellent surface treatment 11. The remaining water droplets can be drained through the flat fins 9b subjected to the adjacent hydrophilic surface treatment 12, and the ventilation resistance at the time of dew condensation Water splashing to increase and heat exchanger back can be suppressed.
[0030]
As described above, the finned heat exchanger of the present embodiment is arranged in parallel at regular intervals, and the fluid flows through the fins 9a and 9b through which the gas flows between the fins 9a and 9b. A plurality of heat transfer tubes 2 and fins 9a and flat fins 9b provided with a plurality of slits 10 on the surface are alternately arranged, and a water-repellent surface treatment 11 is applied to the surface of the slits 10 of the fins 9a. By applying the hydrophilic surface treatment 12 to the surface of the fin 9b, in the fin 9a provided with the slit 10, the formation and growth of frost is strongly delayed by the water-repellent surface treatment 11 to reduce the heat transfer coefficient in the slit 10 and The blockage can be delayed, and the decrease in the amount of heat exchange due to the decrease in the air volume can be significantly suppressed. The remaining water droplets can be drained through the adjacent flat fins 9b provided with a hydrophilic surface treatment 12, can be suppressed water splashing into increased and the heat exchanger rear ventilation resistance during condensation.
[0032]
【The invention's effect】
As described above, the present inventionA fin and a flat fin that are arranged in parallel at regular intervals and composed of fins that allow gas to flow between them, and heat transfer tubes that pass through the fins and that allow fluid to flow through the fins. Are alternately arranged, the thermal boundary layer generated on the fin surface by the slit is updated to promote heat transfer between the airflow and the fin, and even if the slit is blocked by frost formation, the adjacent flat fin Since the airflow can flow in the vicinity, the blockage of the flow path as a whole of the heat exchanger can be delayed, and the rapid decrease in the heat exchange amount due to the decrease in the airflow can be suppressed.
[0033]
In addition, by applying water-repellent surface treatment to the surface of fins with slits and hydrophilic surface treatment to the surface of flat fins, water-repellent surface treatment can be used to strengthen frost formation and growth on fins with slits. Slowing down delays the heat transfer rate and blockage at the slit, greatly reducing the amount of heat exchange due to the decrease in air flow, and bridges the slit when condensation occurs, which is a problem with water-repellent surface treatment. The remaining water droplets can be drained through the adjacent flat fins that have been subjected to the hydrophilic surface treatment, so that the increase in ventilation resistance at the time of condensation and the splashing of water to the back of the heat exchanger can be suppressed.
[Brief description of the drawings]
FIG. 1 is a partially enlarged view of a longitudinal section of a first embodiment of a finned heat exchanger according to the present invention.
2 is a cross-sectional view taken along the line BB in FIG.
FIG. 3 is a partially enlarged view of a longitudinal section showing a fin provided with slits in a second embodiment of a heat exchanger with fins according to the present invention.
FIG. 4 is a partially enlarged view of a longitudinal section showing a flat fin according to the embodiment.
5 is a cross-sectional view taken along the line CC in FIGS. 3 and 4. FIG.
FIG. 6 is a partially enlarged view of a longitudinal section showing a fin provided with a slit in a heat exchanger with fin according to a third embodiment of the present invention.
FIG. 7 is an enlarged view of a vertical cross section showing the flat fin of the embodiment.
8 is a cross-sectional view taken along the line DD in FIGS. 6 and 7. FIG.
FIG. 9 is a perspective view of a conventional finned heat exchanger.
FIG. 10 is a partially enlarged view of a longitudinal section of a conventional finned heat exchanger.
11 is a cross-sectional view taken along line AA in FIG.
[Explanation of symbols]
2 Heat transfer tubes
4 Fin
5 Slit
6 Flat surface
7a, 7b Fin
8 Slit
9a, 9b Fin
10 slits
11 Water repellent surface treatment
12 Hydrophilic surface treatment

Claims (1)

  A fin that is arranged in parallel at regular intervals and includes a fin through which gas flows, and a plurality of heat transfer tubes that pass through the fin and through which fluid flows, and that have a plurality of slits on the surface of the fin And flat fins without slits, a finned heat exchanger with a water repellent surface treatment on the surface of the fins with slits and a hydrophilic surface treatment on the surface of the flat fins.

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