JPS6129692A - Finned heat exchanger - Google Patents

Abstract

PURPOSE:To obtain an outdoor heat exchanger with favorable heat transfer performance under frosted condition by a structure wherein concavities and convexities formed by forming the raised slotted parts of the air inflowing ends of fins are located alternately between fins adjacent to each other. CONSTITUTION:Concavities and convexities formed by a large number of raised slotted parts 6 and 8 at the air inflowing ends of fins are located alternately between fins 7 and 9 adjacent to each other. By setting both the widths (a) and (b) of the concavity and of convexity a little less than twice the fin pitch P, the heights (h) of the raised shotted parts 6 and 8 become smaller than the fin pitch P. Consequently, the configuration, in which two kinds of fins, the one is longer and the other is shorter in the air inflowing direction, are alternately arranged in the direction of the axes of pipes 14, is realized at the air inflowing part of a heat exchanger, resulting in enlarging the fin pitch at the air inflowing part as if the fin pitch is doubled. Even in the state that frost layers are formed at the leading edge 15 of each convexity, the trailing edge 16 of each concavity and the leading edge 17 of each raised shotted part 8 under the frosting condition, the air passage remains enough wide together with the pitch of raised shotted parts 8 being wide and the surface areas of the fins are ensured, resulting in improving the heat transferring property.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an outdoor finned heat exchanger such as a heat pump type air conditioner using air as a heat source.

Conventional structure and its problems During heating or hot water supply operation of a heat pump air conditioner that uses air as a heat source, the outdoor finned heat exchanger functions as an evaporator, and when the ambient air temperature decreases, the evaporation temperature decreases to O' If the temperature is below C, water vapor in the air will adhere to the fin surface as frost and form 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 absolute humidity difference between the ambient air, which is related to the amount of frost formation, and the saturated groove 9 air, which corresponds to the temperature of the heat transfer surface of the heat exchanger, is the largest in the air inlet of fin group 3. Therefore, the air in 747 group 3 Since more frost layer 4 is formed in the inflow part and the spaces between the fins are closed in a short time, the amount of air passing through the system is reduced and the amount of heat exchange is significantly reduced in a short time.

In addition, in order to eliminate the above drawback, as shown in FIG. 2, uneven notches are provided on the front edge of the fins 5, and the fin group is configured such that the unevenness of adjacent fins alternates. ,
It has been considered to widen the fin spacing at the air inflow section, but since the front of the fins 5 is notched, the fin surface area decreases, reducing the amount of heat exchange. Therefore, if the fins 5 are made larger, the volume occupied by the group of fins becomes larger, resulting in a disadvantage that the heat exchanger becomes larger.

OBJECTS OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned conventional drawbacks and to provide an outdoor heat exchanger with good heat transfer performance during frost formation.

Structure of the Invention The fin heat exchanger of the present invention has fins formed with concave portions and convex portions at the air inflow end by cutting and raising, and the concave portions and convex portions of adjacent fins in the air inflow direction alternate. It consists of a group of fins constructed as above, and a group of tubes, which are divided into several parts of the above fin group, through which a refrigerant flows.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 3 to 5.

FIG. 3 is a configuration diagram of the finned heat exchanger of the present invention, in which the fins 7 have concave and convex portions formed at the air inflow end by a large number of cut and raised parts 6, and the fins 7 have concave and convex parts formed by a large number of cut and raised parts 8. B. A fin group 1o in which fins 9 having convex portions and concave portions formed at the air inflow end are arranged alternately, and the concave portions and convex portions of adjacent fins alternate in the air inflow direction; The tube group 12 is attached to the fin group 1Q and includes a large number of tubes 11 through which a refrigerant flows. Note that 13 is an arrow indicating the direction of air inflow.

FIG. 4 is a detailed view of the fin 7, and FIG. 5 is a detailed view of the fin 9.
FIG. In both figures, the widths a and b of the four parts in the air inflow direction and the convex parts are both slightly less than twice the fin spacing p, so that the height h of the cut and raised parts 6 and 8 is greater than the fin spacing p. The structure is designed to be small. Note that 14 is a fin collar to which the pipe is attached.

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 inlet portion of the fin 7°9, that is, the front edge 15. of the convex portion. A frost layer is formed on the rear edge 16 of the recess and the front edge 17 of the cut-and-raised part 8, but this is because the fin spacing of the air inflow part is expanded as described above, and the spacing between the cut-and-raised parts 8 is also wide. Even if the same amount of frost layer is formed as before, the space between the fins will not be blocked, and a wide ventilation path can be ensured.

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.

Furthermore, by providing the cutouts 6 and 8, it is possible to form concave and convex portions at the air inlet end without cutting out the fin, which reduces the surface area of the fin and prevents the thermal boundary layer from being underdeveloped. Since it can be made into a large area, the heat transfer coefficient is improved and the amount of heat exchange is also increased.

Effects of the Invention As described in Section 2, the heat exchanger with fins of the present invention has fins in which concave portions and convex portions are formed in the air inflow portion by cutting and bending.
The fins consist of a fin group in which adjacent fins have alternating concave and convex portions in the air inflow direction, and a group of tubes attached to this fin group through which refrigerant flows. The spacing between the fins at the air inflow section can be expanded without reducing the surface area, ensuring a wide ventilation path during frost formation, reducing the increase in ventilation resistance, reducing the reduction in the amount of air passing through, and allowing heat exchange. The performance of the device can be improved.

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 there is no condensation, which has great practical effects.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional outdoor finned heat exchanger, Fig. 2 is a plan view of a different conventional fin, Fig. 3 is a configuration diagram of the finned heat exchanger of the present invention, and Fig. 4. and FIG. 6 are detailed views of a fin according to an embodiment of the present invention. 6.8... cut and raise, 7.9... fin, 10... fin group, 12... tube group. Figure 1 Figure 3

Claims (1)

[Claims] A fin group in which fins each having a concave part and a convex part formed at the air inflow end by cutting and raising are stacked with gaps so that the concave part and convex part in the air inflow direction of adjacent fins alternate; and the fin group. A finned heat exchanger consisting of a group of tubes that are attached to a pipe and through which refrigerant flows.