JPS61259093A - Finned heat exchanger - Google Patents

Abstract

PURPOSE:To improve the heat transfer rate between air and the front surface of a fin by forming cut and raised portion groups alternately adjacent to each other on the front and rear sides of the fins and intercrossing lines connecting centers of cut and raised portions on the front and rear sides. CONSTITUTION:Between two heat transfer pipes 4 which are provided adjacent stepwise to each other, are provided cut and raised portions 13a-13d on the front side of a fin 9, using two sides parallel to a line stepwisely connecting heat transfer pipe 11 as opening parts 15a and 15b and two sides on two lines parallel with an angle to the main current direction of an air current 12 as leg portions 17a and 17b. Further, cut and raised portions 14a-14d are provided on the rear side of the fin 9. These cut and raised portions on the front and rear sides are provided adjacent to each other to form cut and raised portion groups. The interconnecting point between a straight line connecting respective centers of the cut and raised portions and a straight line connecting the centers of the cut and raised portions on the rear side, is formed on a line connecting the centers of two heat transfer pipes 4 adjacent to each other by holding therebetween cut and raised portion groups 19. As a result, turning flows and turbulent flows are induced in air between fins thereby to improve the heat transfer function of the heat pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a finned heat exchanger widely used in the field of air conditioning equipment or refrigeration equipment.

BACKGROUND OF THE INVENTION A conventional finned heat exchanger, as shown in the perspective view of FIG. The air flows between the fins in the three directions of arrows and exchanges heat with the fluid inside the tube.

In recent years, attempts have been made to improve the heat transfer coefficient between the air and the fins by processing the fins of the finned heat exchanger having such a configuration.

FIG. 4 shows an improved example of the prior art, in which (,) is a plan view, and (b) is a sectional view taken along E-EflJIIC of the same figure (&).

In the figure, 4 is a heat transfer tube, 5 is a fin collar, 6 is a fin, and 7a
~7h is cut and raised, and 8 is air flow. That is, between the heat exchanger tubes 40 adjacent to each other in the step direction, a large number of cut and raised portions 7a to 7h are provided alternately on the front side and the back side of the fins 6. In the case of this fin shape, a thin temperature boundary layer is formed in each of the many cutouts 7a to 7h, and an improvement in heat transfer performance is observed, which is contrary to the so-called boundary layer leading edge effect.

Problems to be Solved by the Invention The heat transfer performance of the fin shape shown in FIG.
The cut-and-raised parts 7a and 7b on the upstream side of the airflow 8 have a large boundary layer leading edge effect and high heat transfer performance, but the cut-and-raised parts 70 to 7h on the downstream side of the airflow 8 have the cut-and-raised parts 7a and 7b on the upstream side of the airflow 8.
The air that has been heat exchanged in advance at 7b flows without being mixed with other air. That is, since the cut and raised portions 7C to 7h enter the temperature boundary layer generated at the cut and raised portions 7a and 7b,
It was found that the heat transfer performance was not very high.

Furthermore, a dead zone occurs on the downstream side of the heat transfer tube 4 with respect to the air flow 8, but the heat transfer performance in this portion is poor. For these reasons, no dramatic improvement in heat transfer performance was observed.

Therefore, the present invention improves heat transfer between the air and the fin surface by adopting a fin shape that promotes air mixing at the cut and raised portion and reduces the dead area that occurs downstream of the airflow of the heat transfer tube. The aim is to increase the rate.

A foolproof way to solve problems
1 The heat exchanger with fins of the present invention is composed of fins arranged in parallel at regular intervals and through which air flows, and heat exchanger tubes inserted at right angles to the fins through which fluid passes, and the stages of the heat exchanger tubes are On the fin surface between the directions, cut and raise the two sides parallel to the straight line connecting the heat exchanger tubes in the step direction as openings, and the other two mutually parallel sides as legs, on the front and back sides of the fin. A plurality of cut-and-raised legs are provided alternately adjacent to each other to form a cut-and-raised group, and two or more cut-and-raised legs on the front side are placed on each extension line of two sides of one cut-and-raised leg on the front side of the cut-and-raised group. Place the edges on the respective extension lines of the two sides of the leg of one cut and raise on the back side, and then cut the other cut on the back side)
Two sides of the raised legs are located, and a straight line connecting the center point of the cut-up on the front side and a straight line connecting the center point of the cut-up on the back side are adjacent in the row direction across the cut-up group.
They intersect on a line segment connecting two heat exchanger tubes, and are symmetrical about the perpendicular bisector of that line segment.

Effect According to the above configuration, the portion where the cut-and-raised portion on the downstream side of the airflow enters into the temperature boundary layer generated by the cut-and-raised portion on the upstream side of the airflow is reduced, and the leading edge effect of the boundary layer at the cut-and-raised portion is fully utilized. . Furthermore, since the cut and raised legs are provided at an angle with the main flow direction of the airflow, a mixing effect of the air flowing inside the cut and raised interior and the air flowing outside can be expected. Further, the airflow having a swirling component induced by the cut and raised legs enhances the above-mentioned mixing effect, and at the same time has the effect of reducing the dead area at the downstream part of the heat exchanger tube. These effects make it possible to dramatically improve the heat transfer coefficient between the air and the fin surface.

Example.

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

1 is a plan view of a fin in a finned heat exchanger according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line FF in FIG. 1, and FIG. 3 is a sectional view taken along line G-- It is a sectional view taken along the line 〇-0'-G'.

As shown in FIG. 1, a heat transfer tube 11 is inserted into a fin collar portion 1o formed by burring at regular intervals on the fin 9, and gas flows in the direction of an arrow 12.

The fin 9 has openings 15a and 15b on two sides parallel to a straight line connecting the heat exchanger tubes 11 in the step direction between two heat exchanger tubes 4 adjacent in the step direction, and an angle in the mainstream direction of the air flow 12. The two sides on two straight lines parallel to each other are the legs 17a and 1.
7b, a plurality of cut-and-raised parts 13a to 13d are provided on the front side of the fins 9, two sides parallel to the straight line connecting the heat exchanger tubes 11 in the step direction are defined as openings 1ea and 1eb, and two adjacent ones in the step direction are provided. The legs 1 of the front side cut and raised portions 13a to 13d are
2 on two straight lines symmetrical to the two extension lines of 7a and 17b
The sides are legs 18a and 18b, and a plurality of raised cut-and-raised parts 14a to 14d are provided on the back side of the fin 9.
d are arranged adjacent to each other alternately to form a cut-and-raised group, and a straight line connecting the center points of each of the cut-and-raised parts 13a to 13d on the front side and a straight line that connects the center points of each of the cut-and-raised parts 14a to 14d on the back side. The intersection is cut-up group 1
It is formed so as to exist on a line segment connecting the centers of two adjacent heat exchanger tubes 4 with 9 interposed therebetween.

According to the above configuration, ■ Since the two open sides of the cut-and-raise are provided offset from each other, the cut-and-raise on the downstream side of the airflow includes a portion located outside the temperature boundary layer generated by the cut-and-raise on the upstream side of the airflow. Therefore, the heat transfer performance in that area is good.

■ Since the cut-and-raised group is provided at an angle to the main flow direction of the air, the air flowing inside the cut-and-raised area and the air flowing outside are in different directions, causing slips and turbulence between the airflows. . This turbulence works to destroy the temperature boundary layer generated by cutting and raising, improving the heat transfer performance of the fins.

■ Since the cut and raised legs are provided at an angle to the main flow direction of the air, airflow with swirling and rotational components due to secondary flow is induced from the legs. This airflow is
(D) It has the effect of mixing the heat-exchanged air with fresh air on the upstream side of the airflow. (11) It has the effect of reducing the dead zone that occurs in the airflow downstream of the heat exchanger tube.

These various effects result in a dramatic improvement in the heat transfer coefficient between the air and the fin surface.

In this embodiment, as shown in FIG. 2, the front side cut-and-raises 13a to 13d and the back side cut-and-raises 14a to 14d are arranged adjacent to each other alternately. Almost the same effect can be obtained even in the case of a shape in which there is a portion that is not raised.

Effects of the Invention The present invention provides a cut and raise opening in the airflow direction between the heat exchanger tubes of the fins so that the cut and raised legs form an angle with the airflow direction. By inducing flow and turbulence with a swirling component, the effect of mixing airflow, promoting turbulence, reducing dead area, and leading edge effect of the boundary layer are fully utilized, and the heat transfer performance between the air and the fin surface is greatly improved. becomes higher.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the fins of a finned heat exchanger showing an embodiment of the present invention, Fig. 2 is a sectional view taken along the line F--F in Fig. 1, and Fig. 3 is a sectional view taken along the line 0-0'-G/ cross-sectional view, Figure 4 (,) is a plan view of the fins of the conventional improved heat exchanger with fins, (b) is a cross-sectional view taken along line E-E in the same figure (,),
FIG. 5 is a perspective view of a conventional finned heat exchanger. 9...Fin, 1o...Fin collar, 11...Heat transfer tube, 12...Airflow, 1
3a-13d...Front side cut and raised, 14a-1
4d...Cut and raise the back side, 15a, 15b...
...Front side cut and raised opening, 16a, 1eb
...Back side cut and raised opening, 17a. 17b...Front side cut and raised legs, 18a, 18
b...Back side cut and raised leg part, 19...
Cut-up group. Name of agent: Patent attorney Toshio Nakao and 1 other person9-
1-Fin 10--Fin 4η L/I--1 Im Island 1 Sunny 12-1 Ichiki jt 1st Figure 1 113t-11 Table 1#j t/7 no elm 14l ~ 14tL- -Ichiura bond jvI soori 1, /6b--4KIJ91')
& 2 μ * [7#1516a, /9--Ichiura Yorikiri IL Kot's l/l0IP! 7,1.17b---L4
Asu v J') &: tnlP bond A nine/1b--one crush 5s
vr-up-up leg segment l-cut-up l-to-A-work--aburi 1 cut-up Fig. 4 @N Cb) Fig. 5

Claims (3)

[Claims] (1) Consisting of fins arranged in parallel at regular intervals, through which gas flows, and heat transfer tubes inserted at right angles to the fins, through which fluid passes, the fins are located between the heat transfer tubes in the stepwise direction. On the surface, two sides parallel to the straight line connecting the heat exchanger tubes in the step direction are made into openings, and the other two mutually parallel sides are made into legs, and cut and raised portions are made alternately on the front side and the back side of the fins. A plurality of them are provided adjacently to form a cut-up group,
On the respective extension lines of the two sides of one cut-and-raised leg on the front side of the cut-and-raised group, two sides of the other cut-and-raised leg on the front side are located, and one of the cut-and-raised legs on the back side is located. Position the two sides of the other cut-and-raised legs on the back side on the respective extension lines of the two sides of the legs of A heat exchanger with fins formed so that the straight lines connecting the center points intersect. (2) A straight line connecting the center point of the cut-and-raised portion on the front side and a straight line that connects the center point of the cut-and-raised portion on the back side is a line segment that connects the centers of two heat exchanger tubes adjacent in the row direction across the cut-and-raised group. The finned heat exchanger according to claim 1, which is formed symmetrically with respect to a perpendicular bisector of the finned heat exchanger. (3) A straight line connecting the center point of the cut-and-raised portion on the front side and a straight line that connects the center point of the cut-and-raised portion on the back side is a line segment that connects the centers of two heat exchanger tubes that are adjacent in the row direction across the cut-and-raised group. The finned heat exchanger according to claim 1 or 2, which is formed to intersect at the top.