Fin-tube heat exchanger, fin for heat exchanger, and heat pump apparatus

Abstract

A fin-tube heat exchanger 1 includes a plurality of fins 3 arrayed spaced apart from and parallel to each other so as to form gaps for allowing a first fluid to flow therethrough, and a plurality of heat transfer tubes 2 penetrating the plurality of fins 3 and for allowing a second fluid to flow therethrough. The plurality of heat transfer tubes 2 includes first heat transfer tubes 2A and second heat transfer tubes 2B arranged in a predetermined row direction that intersects the flow direction of the first fluid. The fins 3 have protrusions 5 each disposed between a first heat transfer tube 2A and a second heat transfer tube 2B, for guiding the first fluid toward the first heat transfer tube 2A side and the second heat transfer tube 2B side. The equivalent diameter of the protrusion 5, as viewed in the axis direction of the heat transfer tubes 2, is equal to or greater than the outer diameter of the heat transfer tubes 2.

Description

TECHNICAL FIELD[0001]The present invention relates to fin-tube heat exchangers, fins for heat exchangers, and heat pump apparatuses.BACKGROUND ART[0002]Conventionally, fin-tube heat exchangers have been used for various apparatuses such as air conditioners, freezer-refrigerators, dehumidifiers, and hot water heaters. A fin-tube heat exchanger is composed of a plurality of fins that are arranged parallel to each other and spaced apart with a predetermined gap, and heat transfer tubes that extend through these fins.[0003]Known fin-tube heat exchangers include ones with various fin shape designs so as to, for example, enhance heat transfer and reduce pressure loss. For example, in a fin-tube heat exchanger, the leeward side of the heat transfer tube usually becomes a dead fluid zone, in which the heat transfer coefficient is locally low. In view of this, there are known fin-tube heat exchangers having fins provided with protuberances on the surfaces of the fins so as to reduce the dead...

AI Technical Summary

Benefits of technology

[0148]As illustrated in FIGS. 14 and 20, the width of the protrusions 35, 51 increases from the upstream edges 5f, 51f to the intermediate portions 5b, 51b, while it decreases from the intermediate portions 5b, 51b to the downstream edges 5e, 51e. The upstream edges 5f, 51f of the protrusions 35, 51 are located upstream of the centers C1 and C2 of the heat transfer tubes 2A and 2B. The intermediate portions 5b, 51b of the protrusions 35, 51 are located upstream of the downstream edges 2e of the heat transfer tubes 2A and 2B. The equivalent diameter d of the protrusions 35, 51 is equal to or greater than the diameter D of the heat transfer tubes 2. The height of the protrusions 35, 51 may be either greater or less than the fin pitch, or it may be equal to the fin pitch. With such a configuration, the same advantageous effects as in Embodiment 1 can be obtained.

[0149]A fin 32 shown in the plan view of FIG. 21 suitably may be employed for the fin-tube heat exchanger 1. The arrangement and dimensions of the heat transfer tubes 2 are common to those in Embodiment 4. The difference is that second protrusions 53 are formed between the protrusions 35 formed in the front row and the other protrusions 35 formed in the rear row, the second protrusions 53 having a surface area smaller than the foregoing protrusions 35, 35. Strictly speaking, in FIG. 21, which is a plan view showing the fin 32 viewed in plan from the height direction (Y direction) perpendicular to the principal surface, the diameter d4 of the second protrusions 53 is smaller than the outer diameter D of the heat transfer tubes 2. In addition, the second protrusions 53 protrude in the same direction as the protrusions 35, 35 in the front row and the rear row.

[0150]In the fin 30 according to Embodiment 4 (see FIG. 14), there is a little space between the protrusions 35 in the front row and the protrusions 35 in the rear row. By forming the second protrusions 53 in this space, the heat transfer area increases. In particular, the region in which the second protrusions 53 are formed serves as a passage of the air A whose flow velocity has been increased by the effect of the protrusions 35 in the front row. Therefore, by allowing the air A with an increased flow velocity to hit the second protrusions 53 intentionally, it is possible to improve the heat transfer performance further. Such second protrusions 53 may have a circular hump shape as in the present embodiment, or they may have an elliptical hump shape.

[0151]In addition, a fin 33 as illustrated in FIG. 22 also can be employed suitably for the same reasons as described above. In the fin 33, protrusions 51, 51 in a circular hump shape are formed in the front row and the rear row in place of the protrusions 35 in an elliptical hump, and second protrusions 53 having a smaller surface area than the protrusions 51, 51 are formed between the protrusions 51 in the front row and the protrusions 51 in the rear row.Embodiment 7

[0152]The protrusions 35, 51, and 53 described in Embodiments 4 to 6 are formed so that all the protrusions protrude in the same direction. However, as has been mentioned in Embodiment 1, this is not essential. Specifically, a fin 34 as illustrated in FIGS. 23A and 23B may be suitably employed as the fin for the fin-tube heat exchanger 1. In the fin 34, protrusions 35 protruding from a first principal surface 34j side (the obverse side of the fins 34) and protrusions 35′ protruding from a second principal surface 34k side (the reverse side of the fin 34) coexist.

[0153]When the protrusions 35, 35′ with different protruding directions are formed to coexist as described above, the following effects are achieved. A fin in which all the protrusions protrude in the same direction is produced through the following steps: the step of cutting a metal plate into a predetermined size, the step of forming through holes for accommodating the heat transfer tubes, and the step of forming the protrusions in the metal plate by a pressing process. When the protruding direction of the protrusions is limited to one direction, the metal plate warps during the step of forming the protrusions, resulting in warpage in the fin obtained. If such warpage occurs, there may be cases in which, when assembling the heat exchanger, the fin pitch becomes non-uniform or the heat transfer tubes cannot be inserted smoothly in the through holes because of misalignment of the through holes.

Problems solved by technology

In recent years, demands for reducing energy consumption of heat pump apparatuses used for hot water heaters and air conditioners have been growing due to various issues such as urban heat island issues, natural resource issues, and global environment issues.

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