JPS6183892A - Heat exchanger having fin - Google Patents

Abstract

PURPOSE:To obtain good heat transmission performance when frosted by providing fins forming alternating depressions and protrusions at the air inlet side and pipes which are attached to the fins and refrigerant flows therein. CONSTITUTION:By multiple cut and raised strips 6, depressions and protrusions are formed on the air inlet side. The strips 6 are drilled a hole 7. A pipe stack 11 consisting of multiple pipes 10 in which the refrigerant flows is attached to a fin stack 9 in which neighboring fins 8 make up the depressions and protrusions on the air inlet side. When the width (a) and (b) of the depression and protrusions on the air inlet side is made slightly smaller than twice the fin pitch (p), the height (h) of the cut and raised strips 6 becomes smaller than the fin pitch (p). In this arrangement, a frost layer is formed at the leading edge 13 of the protrusions, trailing edge 14 of the depressions and leading edge 15 of the strips 6 of the fins 8, but because the fin pitch is wide and the space between the strips 6 is also wide, the space between the fins is not blocked, preventing a reduction in the heat exchanging rate. Further, when defrosting, the frost melt is quickly drained out of the holes 7 and will not stay on the strips 6, ensuring a high performance when frosted and defrosting.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a heat exchanger with fins used for outdoor use in a heat pump type air conditioner using air as a total heat source.

Conventional configuration and its problems During heating or hot water supply operation of a heat pump air conditioner that uses air as a heat source, an outdoor finned heat exchanger functions as an evaporator, and when the ambient air temperature drops, the evaporation temperature drops to 0. ℃ or below, water vapor in the air adheres to the fin surface as frost, forming a frost layer.

As shown in Figure 1, a conventional outdoor finned heat exchanger consists of a tube group 1 through which refrigerant flows, and a flat plate attached at regular intervals to the tube group 1 through which air flows in the two directions of the arrows. It is composed of a fin group 3.

The air inflow portion of the fin group 3 has the largest absolute humidity difference between the ambient air, which is related to the amount of frost formed, and the saturated humid air, which corresponds to the temperature of the heat transfer surface of the heat exchanger.

Therefore, more frost layer 4 is formed at the air inflow part of the fin group 3, and the spaces between the fins are closed in a short time, which has the disadvantage that the amount of air passing through is reduced and the amount of heat exchange is significantly reduced in a short time. was.

In addition, in order to eliminate the above drawback, as shown in FIG. 2, uneven notches are provided on the front edges of the fins 6, and the fin group is configured such that the unevenness of adjacent fins alternates. ,
Increasing the fin spacing is also being considered, but fin 5
The leading edge of the fin is notched, which reduces the fin surface area and reduces the amount of heat exchange.
If the fins 5'' were made larger, the volume occupied by the fin group would become larger, resulting in a disadvantage that the heat exchanger would become larger.

OBJECTS OF THE INVENTION An object of the present invention is to eliminate the above-mentioned conventional drawbacks and to provide a finned heat exchanger that exhibits good heat transfer performance during frosting.

Structure of the Invention The heat converter with fins of the present invention has a concave portion and a convex portion formed at the air inflow end by cutting and raising, and adjacent fins having cutouts or holes formed in the cut and raised portions. It is composed of a group of fins arranged such that concave portions and convex portions at the air inflow ends of the fins are arranged alternately, and a group of tubes attached to the fin group, through which a refrigerant flows.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG.

FIG. 3 shows the configuration of the finned heat exchanger of this example,
A large number of cut and raised portions 6 form concave portions and convex portions at the air inflow end, and a fin 8 having holes 7 formed in the cut and raised portions 6 is formed at the air inflow end portion of adjacent fins 8. The fin group 9 is constituted by arranging the concave portions and convex portions thereof alternately,
A finned heat exchanger is constituted by a tube group 11 consisting of a large number of tubes 10 attached to the fin group 9 and through which a refrigerant flows. Note that 12 is an arrow indicating the direction of air inflow.

FIG. 4 shows details of the air inlet end of the fin 8. By making the widths a and bl of the concave part and the convex part at the air inflow end a little less than twice the fin spacing p, the height h of the cut-and-raised part 6 is
The configuration is such that the fin spacing is smaller than the fin spacing p.

By adopting the above configuration, in the air inflow section, long fins and short fins in the air inflow direction are arranged alternately in the tube axis direction, as if the fin spacing had doubled. , the fin spacing of the air inflow section is expanded. Therefore, even when used under frost conditions, the air inflow portion of the fin 8, that is, the front edge 13 of the convex portion, the rear edge 14 of the concave portion, and the front edge 15 of the cut and raised portion 6,
As mentioned above, since the fin spacing of the air inflow section has been expanded and the spacing between the cut and raised grooves 6 is wide, even if the same amount of frost layer is formed as before, A wide ventilation path can be ensured without being blocked between the fins. Therefore, there is only a small increase in ventilation resistance, a small decrease in the amount of passing air, and a small decrease in the amount of heat exchange. In addition, even during defrosting, since the holes 7 are provided in the cut-and-raised portions 6, melt water is quickly removed from the holes 7 and does not accumulate on the cut-and-raised portions 6. It can maintain high performance even during repeated operations of frosting and defrosting.

Note that by burring the holes 6, the melt water can be removed more quickly. Furthermore, by providing the cut-and-raised portion 6, all the concave and convex portions can be formed at the air inflow end without cutting out the fin, and even if the hole 7 is provided in the cut-and-raised portion 6, the fin surface area is The reduction is extremely small, and the area where the temperature boundary layer has conventionally developed, such as the trailing edge 14 of the recess, can be made into a new area where the temperature boundary layer has not developed. This improves the transfer rate and increases the amount of heat exchange.

FIG. 5 shows details of the air inlet end of the fins of another embodiment of the finned heat exchanger of the present invention. At the air inflow end of the fin 16, a concave portion and a convex portion are formed by a cut-and-raised portion 17, and a cut-out portion 18 is formed in the cut-and-raised portion 17. In this fin configuration as well, the cutout portion 18 plays the role of the hole A of the previous embodiment, and provides similar functions and effects.

Effects of the Invention As is clear from the above explanation, the finned heat exchanger of the present invention has a concave portion and a convex portion formed at the air inflow end by the cut-and-raised portion, and a notch or a convex portion in the cut-and-raised portion. A fin group in which fins with holes are arranged such that the concave and convex portions of the air inflow ends of adjacent fins are alternately located, and a group of tubes attached to the fin group through which refrigerant flows. Because of this structure, the decrease in the fin surface area is extremely small, and the fin spacing at the air inflow section can be expanded, ensuring a wide ventilation path during frost formation, reducing the increase in ventilation resistance, and increasing the amount of passing air. It is possible to reduce the decrease in heat exchanger performance and improve the performance of the heat exchanger. Furthermore, melt water can be quickly removed during defrosting, and high performance can be maintained even during repeated frosting and defrosting operations. Furthermore, by providing the cut and raised portions, the heat transfer coefficient of the fins is improved, and the performance of the heat exchanger is improved even when frost is not formed, which has great practical effects.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional outdoor finned heat exchanger, Figure 2
The figure is a plan view of another conventional fin, FIG. 3 is a perspective view of a heat exchanger with fins showing an embodiment of the present invention, FIG. 4 is a perspective view of the same main part, and FIG. It is a principal part perspective view of the fin of the finned heat exchanger which shows another Example. 6... cut and raise, a... hole, 8...
...Fin, 9...Fin group, 10...
・Pipe, 11...tube group, 16...fin, 1 finish...cut and raised, 18...notch part. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure! Figure 2 Porridge Figure 3

Claims (1)

[Claims] By cutting and raising, a concave part and a convex part are formed at the air inflow end, and a fin with a notch or a hole formed in the cut and raised part is formed so that the concave part and the convex part at the air inflow end of adjacent fins are formed. A heat exchanger with fins is composed of a group of fins arranged alternately and a group of tubes attached to the fin groups, through which a refrigerant flows.