JP2013120044A - Fin tube heat exchanger and method for manufacturing same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fin tube heat exchanger capable of considerably reducing ventilation resistance by sufficiently improving a hydrophilic property.SOLUTION: In at least part of a heat transfer fin, a plurality of concave condensed water discharge grooves are formed so as to discharge condensed water on a heat transfer fin surface and at least part of the plurality of concave condensed water discharge grooves are inclined relative to a flow direction of a gas flowing in a plane direction of the heat transfer fin and formed so as to extend toward a bottom end of the heat transfer fin or the side end of the heat transfer fin at the downstream side of the gas flowing in the plane direction in which an area ratio (A/B) of a surface area A at an interval D from a center of the concave condensed water discharge groove to a center of the neighboring concave condensed water discharge groove and a surface area B at a length equal to the interval D is set so as to be not shorter than 1.0 and not longer than 2.0.

Description

  The present invention relates to a finned tube heat exchanger that is provided in an air conditioner, a hot water supply device, and the like and performs heat exchange with air and a method for manufacturing the same.

  Generally, it is composed of a large number of heat transfer fins that are arranged in parallel at a predetermined interval and gas flows between them, and a large number of heat transfer tubes that are inserted into the heat transfer fins at substantially right angles and through which refrigerant flows. Fin tube heat exchangers are widely used as air conditioners, condensers or evaporators for water heaters.

  When a finned tube heat exchanger is used as the evaporator, if the surface temperature of the heat transfer fins falls below the dew point of the air that performs heat exchange, moisture in the air will condense, forming water droplets on the surface of the heat transfer fins, or transferring heat. Moisture cross-linking (bridge) between the heat fins and the raised part occurs. And the air flow path between fins will be obstruct | occluded with this condensed water, and the increase in ventilation resistance will be caused. As a result, there is a problem that the power consumption of the air conditioner and the hot water supply device is increased and the energy efficiency is lowered.

  Therefore, for example, as shown in Prior Art Document 1, by forming a hydrophilic film (hydrophilic coating layer) on the surface of the heat transfer fin and reducing the contact angle with respect to water, the heat transfer fin between the generated heat transfer fins It is common to prevent blockage of the air flow path.

  However, it is difficult to say that the formation of a hydrophilic film on the surface of the heat transfer fin can sufficiently suppress the blockage of the air flow path due to condensed water. Therefore, in Prior Art Document 2, the hydrophilicity is further improved by performing plasma irradiation on the hydrophilic film (hydrophilic coating layer) on the surface of the heat transfer fin to form fine irregularities.

JP 2010-175131 A

Surface Technology, Vol. 57, p. 127 (2006).

  As shown in Patent Document 1, in order to form fine irregularities on the surface of the heat transfer fin, an expensive processing process such as plasma irradiation is required, and there is a problem that the manufacturing cost is remarkably increased.

  The present invention has been made in view of the above circumstances, and its purpose is to sufficiently enhance the hydrophilicity of the heat transfer fin surface by an inexpensive processing process and to have excellent durability, and its fin tube heat exchanger. It is to provide a manufacturing method.

  Moreover, in the nonpatent literature 1, there exists a subject which cannot fully suppress obstruction | occlusion of the air flow path between heat-transfer fins.

In order to solve the above-described conventional problems, a finned tube heat exchanger according to the present invention includes a large number of heat transfer fins that are arranged in parallel at predetermined intervals and through which gas flows, and substantially perpendicular to the heat transfer fins. In a finned tube heat exchanger configured with a large number of heat transfer tubes that are inserted in and through which refrigerant flows, a plurality of concave shapes for discharging condensed water on the surface of the heat transfer fins to at least a part of the heat transfer fins And at least a part of the plurality of concave condensate drain grooves is inclined with respect to the flow direction of the gas flowing in the plane direction of the heat transfer fins, and the bottom ends of the heat transfer fins Of the concave condensate drain groove adjacent to the central portion of the concave condensate drain groove, and extending toward the side end of the heat transfer fin on the downstream side of the gas flowing in the plane direction. In the distance D to the center And a surface area A, the surface area ratio of the surface area B of the distance D equal to length (A / B) is configured to be 2.0 times or less 1.0 times or more.

  According to the above configuration, the condensed water condensed on the heat transfer fin surface is stretched by the concave condensed water discharge groove. Further, the concave condensate drain groove is inclined with respect to the flow direction of the gas flowing in the plane direction and is directed toward the bottom end portion of the heat transfer fin or the side end portion of the heat transfer fin on the downstream side of the gas flowing in the plane direction. Therefore, the condensed water can be quickly discharged from the heat transfer fins using the dynamic pressure of the flowing gas and the weight of the condensed water.

  According to the present invention, the hydrophilicity of the heat transfer fin surface can be sufficiently increased, and the condensed water condensed on the heat transfer fin surface can be quickly discharged by the concave condensed water discharge groove. Therefore, the air flow path can be reliably prevented from being blocked by the condensed water condensed on the surface of the heat transfer fins, so that the increase in ventilation resistance can be suppressed.

The block diagram of the finned-tube heat exchanger of embodiment of this invention The block diagram of the heat-transfer fin of embodiment of this invention Conceptual diagram showing the effect of the present invention Detailed view (cross-sectional view) of the concave condensate drain in the present invention The figure for demonstrating the surface area ratio (A / B) in this invention The figure which showed the relationship between the surface area ratio (A / B) and contact angle in embodiment of this invention

  The first invention is a large number of heat transfer fins that are arranged in parallel at a predetermined interval and through which gas flows, and a large number of heat transfer tubes that are inserted substantially perpendicular to the heat transfer fins and through which refrigerant flows. In the finned tube heat exchanger, the plurality of concave condensate discharge grooves for discharging condensed water on the surface of the heat transfer fins are provided in at least a part of the heat transfer fins. At least a part of the condensed water discharge groove is inclined with respect to the flow direction of the gas flowing in the plane direction of the heat transfer fin, and the bottom end of the heat transfer fin or the downstream side of the gas flowing in the plane direction. A surface area A in a distance D from a central part of the concave condensate water discharge groove to a central part of the adjacent concave condensate water discharge groove formed to extend toward the side end of the heat fin, and the distance D Surface area B with length equal to Surface area ratio (A / B) is configured to be 2.0 times or less 1.0 times or more.

  According to the above configuration, the condensed water condensed on the heat transfer fin surface is stretched by the concave condensed water discharge groove. Further, the concave condensate drain groove is inclined with respect to the flow direction of the gas flowing in the plane direction and is directed toward the bottom end portion of the heat transfer fin or the side end portion of the heat transfer fin on the downstream side of the gas flowing in the plane direction. Therefore, the condensed water can be quickly discharged from the heat transfer fins using the dynamic pressure of the flowing gas and the weight of the condensed water.

Further, the surface area A in the distance D from the central part of the concave condensate water discharge groove to the central part of the adjacent concave condensate water discharge groove, the concave condensate water discharge groove is not formed, and the distance D Ensuring sufficient hydrophilicity and durability by forming the condensate drainage groove so that the surface area ratio (A / B) to the surface area B is equal to or greater than 1.0 and less than or equal to 2.0 Is possible.

  According to a second invention, in addition to the first invention, the heat transfer fin includes a fin material as a base material and a plurality of coating layers formed in an upper layer of the fin material, and at least one of the plurality of coating layers. One layer is composed of a hydrophilic film.

  According to the said structure, the contact angle with respect to the water of a fin surface can be easily made into 5 degrees or less (super hydrophilicity) by forming a concave condensed water discharge groove in the heat-transfer fin surface in which the hydrophilic membrane | film | coat was formed. it can.

  According to a third invention, in addition to the first or second invention, the fin material is made of an aluminum material.

  According to the said structure, a concave condensed water discharge groove | channel can be processed easily by press work.

  According to a fourth aspect of the present invention, in addition to the first to third aspects, the step of forming the condensed water discharge groove by pressing after forming the hydrophilic film on the upper layer of the fin material.

  According to the above configuration, since the condensed water discharge groove is formed by pressing after the hydrophilic film is formed, the entire heat transfer fin surface has a water contact angle of 5 degrees or less (superhydrophilic) easily and uniformly. can do.

(Embodiment 1)
Hereinafter, embodiments of a fin tube heat exchanger and a method for manufacturing the same according to the present invention will be described with reference to the drawings. Drawing 1 is a lineblock diagram of a fin tube heat exchanger of an embodiment of the present invention.

  The finned tube heat exchanger of the present embodiment has a large number of heat transfer fins 1 arranged at predetermined intervals and through which gas flows, and is inserted into the heat transfer fins 1 at a substantially right angle so that the refrigerant flows through the inside. It is composed of a large number of heat transfer tubes 2, the contact angle of the surface of the heat transfer fin 1 with respect to water is 30 degrees or less, and condensed water condensed on the surface of the heat transfer fin 1 is formed on at least a part of the heat transfer fin 1. It has a plurality of concave condensate drain grooves 3 to be discharged, at least a part of the plurality of concave condensate drain grooves 3 is inclined with respect to the flow direction of the gas 4 flowing in the plane direction, and heat transfer It is formed by extending toward the bottom end portion 5 of the fin 1 or the side end portion 6 of the heat transfer fin 1 on the downstream side of the gas 4 flowing in the plane direction.

  About the material of the surface of the heat-transfer fin 1, it is preferable to use the metal whose contact angle is 30 degrees or less. However, when a metal is exposed to air or moisture, an oxide film or a corrosion product is formed, so that the contact angle tends to increase. Therefore, a hydrophilic film is often formed on the surface of the heat transfer fin 1 by surface treatment or the like. FIG. 2 is a configuration diagram of the heat transfer fin according to the embodiment of the present invention. As shown in this figure, the fin material 7, the corrosion resistant film 8, the hydrophilic film 9, and the lubricating film 10 are formed from the lower layer.

  About the fin material 7 shown in FIG. 2, what can form a condensed water discharge groove | channel by press work is preferable. Specifically, steel materials, copper materials, and aluminum materials can be applied, but aluminum materials are used in the embodiments of the present invention. The corrosion-resistant film 8 was formed by phosphoric acid chromate treatment.

  As the hydrophilic film 9, an inorganic (water glass, boehmite), organic resin, or organic / inorganic composite film can be used. In the embodiment of the present invention, the organic / inorganic composite silica / resin composite film was formed by chemical conversion treatment.

  The lubricating film 10 is for improving the lubricity when the heat transfer fins 1 are pressed. When the water-soluble film is used, it is easily lost by moisture. Therefore, the hydrophilicity of the hydrophilic film 9 is not lowered by the lubricating film 10 formed in the upper layer. Thus, if at least one of the plurality of coating layers is composed of a hydrophilic coating, the effects of the present invention can be more efficiently exhibited.

  FIG. 3 is a conceptual diagram showing the effect of the present invention. As shown in this figure, the condensed water 11 condensed on the surface of the heat transfer fin 1 is stretched along the concave condensed water discharge groove 3. As a result, the contact angle (B) with respect to water seen from the flow direction of the gas 4 flowing in the plane direction is greatly reduced with respect to the contact angle (A) with respect to water seen from the extending direction 12 of the condensed water discharge groove. Can do. Therefore, the increase in ventilation resistance (pressure loss) between the heat transfer fins 1 due to the gas 4 flowing in the plane direction and the condensed water 11 condensed on the surface can be greatly reduced.

  Further, the concave condensate drain groove 3 is inclined with respect to the flow direction of the gas 4 flowing in the plane direction, and the bottom end portion 5 of the heat transfer fin 1 shown in FIG. If it is formed by extending toward the side end portion 6 of the heat fin 1, the condensed water 11 condensed from the heat transfer fin 1 can be quickly utilized by utilizing the dynamic pressure of the gas 4 flowing in the plane direction and the weight of the condensed water. Can be discharged.

  FIG. 4 is a detailed view (cross-sectional view) of a concave condensed water drain in the present invention. The diameter of the opening 13 shown in the figure is preferably 1 mm or less in order to fully utilize the capillary effect. By taking such a configuration, the condensed water condensed on the surface of the heat transfer fin is attracted to the concave condensed water discharge groove, and the contact angle with respect to the water as viewed from the flow direction of the gas 4 flowing in the plane direction in FIG. It can be quickly reduced. Furthermore, if the hydrophilic film 9 is formed as shown in FIG. 2, a superhydrophilic surface having a contact angle of 5 degrees or less can be easily realized. Therefore, the ventilation resistance (pressure loss) due to the gas 4 flowing in the plane direction and the condensed water 11 condensed on the surface between the heat transfer fins 1 can be further effectively reduced.

  FIG. 5 is a diagram for explaining the surface area ratio (A / B) in the present invention. 5A shows the upper surface 14 and the cross section 15 of the portion where the concave condensed water discharge groove is formed, and B) shows the upper surface 16 and the cross section 17 of the portion where the concave condensed water discharge groove is not formed. As shown in FIG. 5A), in the cross section 15, the distance from the central part of the concave condensate water discharge groove to the central part of the adjacent concave condensate water discharge groove is D, and the surface area of the upper surface 14 corresponding to the distance is D. Is A. 5B) has the same length as the distance D shown in the cross section 15, and the surface area of the upper surface 16 corresponding to the distance is B.

  In the present invention, the surface area ratio (A / B) between the surface area A and the surface area B is 1.0 to 2.0 times. The reason is explained.

  Even when a hydrophilic metal is used as the fin material, if a fine press process is performed more than necessary, the press mold is likely to be worn, resulting in an increase in manufacturing cost.

  In addition, when the hydrophilic film is formed as in the embodiment of the present invention, if the condensed water discharge groove formed by pressing is excessively refined, the hydrophilic film is lost and the effect of hydrophilization is obtained. It will not be fully demonstrated.

FIG. 6 is a diagram showing the relationship between the surface area ratio (A / B) and the contact angle in the embodiment of the present invention.
Here, A / B = 1 corresponds to the case where the condensed water discharge groove is not formed. Moreover, the contact angle shown in this figure is the water seen from the flow direction of the gas 4 flowing in the plane direction shown in FIG. 3B when the condensed water discharge groove is formed (A / B> 1). The contact angle with respect to.

  Next, an experimental method performed to obtain the relationship shown in FIG. 6 will be described. First, the heat transfer fin according to the embodiment of the present invention in which no condensed water discharge groove was formed was cut into a 5 cm square to obtain a test piece. And the various test pieces which formed the condensed water discharge groove of predetermined surface area ratio were produced by press work. As a hydrophilic durability test method, these various test pieces were put in a beaker, immersed in running water for 8 hours, and then dried for 16 hours in a constant temperature layer at 80 ° C. for 1 cycle, and this operation was performed for 5 cycles. The subsequent contact angle was measured.

  As shown in FIG. 6, if A / B is 1.0 times or more, even after the endurance test (□), the initial stage (▲) (A / B = 1) in which no condensed water discharge groove is formed. ), The contact angle is smaller than that, and sufficient hydrophilicity can be exhibited.

  Moreover, when it becomes 1.2 times or more, even if it is after an endurance test (□), it turns out that the contact angle is 5 degrees or less (superhydrophilic). However, when the surface area ratio (A / B) reaches 1.8 times, the contact angle after the endurance test (□) begins to become larger than 5 degrees, and when the contact angle becomes 2.1 times, the contact after the endurance test The angle (□) becomes larger than the initial (▲) (A / B = 1) in which the condensed water discharge groove is not formed. Thus, when A / B is increased, that is, when the condensed water discharge groove is made finer, the hydrophilicity is rather deteriorated. This is because the hydrophilic film formed on the heat transfer fin is lost when a fine condensed water discharge groove is provided. Therefore, since such a phenomenon occurs, the surface area ratio (A / B) is preferably 1.0 to 2.0 times.

  As described above, according to the present embodiment, it is possible to effectively reduce the ventilation resistance between the heat transfer fins while quickly discharging the condensed water on the surface of the heat transfer fins. Further, since high performance can be achieved by an inexpensive processing process such as press processing, it is possible to realize a manufacturing method of a fin tube heat exchanger that is cost-effective.

  As described above, the finned tube heat exchanger and the manufacturing method thereof according to the present invention sufficiently increase the hydrophilicity and quickly discharge the condensed water condensed on the surface of the heat transfer fin by the concave condensed water discharge groove. Therefore, it can be applied as a heat exchanger of an air conditioner.

1 Heat Transfer Fin 2 Heat Transfer Tube 3 Concave Condensate Drain Groove 4 Gas Flowing in Plane Direction 5 Bottom End of Heat Transfer Fin 1 6 Side End of Heat Transfer Fin 1 7 Fin Material 8 Corrosion Resistant Film 9 Hydrophilic Film 10 Lubrication 11 Condensed water condensed on the surface 12 Stretch direction of the condensed water discharge groove 13 Opening portion 14 Upper surface of the portion where the concave condensed water discharge groove is formed 15 Cross section of the portion where the concave condensed water discharge groove is formed 16 Condensed condensate The upper surface of the portion where the water discharge groove is not formed. 17 The cross section of the portion where the concave condensed water discharge groove is not formed.

Claims (4)

Fins composed of a large number of heat transfer fins that are arranged in parallel at predetermined intervals and through which gas flows, and a large number of heat transfer tubes that are inserted substantially perpendicular to the heat transfer fins and through which refrigerant flows. In the tube heat exchanger, at least a part of the heat transfer fins has a plurality of concave condensed water discharge grooves for discharging condensed water on the surface of the heat transfer fins, and at least of the plurality of concave condensed water discharge grooves. Part of the heat transfer fin is inclined with respect to the flow direction of the gas flowing in the plane direction, and the bottom end of the heat transfer fin or the side end of the heat transfer fin on the downstream side of the gas flowing in the plane direction And a surface area A in a distance D from a central portion of the concave condensed water discharge groove to a central portion of the adjacent concave condensed water discharge groove, and a surface area in a length equal to the distance D. Surface area ratio with B ( / B) of the fin tube heat exchanger, characterized in that it is 2.0 times or less 1.0 times or more. The heat transfer fin includes a fin material serving as a base material and a plurality of coating layers formed on an upper layer of the fin material, and at least one of the plurality of coating layers is formed of a hydrophilic coating. The described finned tube heat exchanger. The finned tube heat exchanger according to claim 1 or 2, wherein the fin material serving as a base material of the heat transfer fin is an aluminum material. The manufacturing method of the finned-tube heat exchanger in any one of Claim 1 to 3 which forms the said condensed water discharge groove | channel by press work after forming the said hydrophilic film in the upper layer of the said fin material.