JPS6338892A - Finch tube heat exchanger - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fin-tube heat exchanger used in air conditioners, refrigeration, refrigerators, etc., which transfers heat between a refrigerant and a fluid such as air.

2. Description of the Related Art As shown in the perspective view of FIG. 3, a conventional fin-tube heat exchanger of this type includes a group of plate-like fins 1 arranged in parallel at regular intervals, and a group of plate-like fins arranged at right angles to the group of plate-like fins 1. The airflow 3 flows between the plate-shaped fin groups 1 and exchanges heat with the refrigerant flowing within the heat exchanger tube group 2. In recent years, such fin-tube heat exchangers have been required to be smaller and have higher performance, but the airflow velocity between the fins is kept low from the viewpoint of noise etc., so the heat inside the heat exchanger tubes is reduced. The thermal resistance on the air side is higher than the resistance.

Therefore, efforts are currently being made to reduce the difference in thermal resistance from the inside of the heat transfer tube by expanding the heat transfer area on the air side. However, there are physical limits to expanding the heat transfer surface, as well as economic limitations.

There are also problems in terms of space saving, etc., and reducing the thermal resistance on the air side is an important issue in this type of fin tube type A exchanger.

FIGS. 4 and 5 show an example of a conventional fin-tube type heat exchanger. FIG. 4 shows a partial side view, and FIG. 6 shows a DD/sectional view. This conventional example is called a slit fin with a staggered tube arrangement, and a large number of slit-shaped cut-and-raised portions 5a to 6d are provided between the heat transfer tubes 2 of the plate-shaped fin 1.

A refrigerant such as fluorocarbon is circulated inside the heat transfer tube 2, and the heat is transmitted from the heat transfer tube 2 to the fin collar 4, and then to the plate-shaped fins 1 and the raised cutouts 6a to 6d. On the other hand, the airflow 3 passes between the plate-shaped fins 1, but at that time, it exchanges heat with the plate-shaped fins 1 whose temperature is different. Due to this action, heat exchange between the refrigerant and the air is performed continuously.

Problems to be Solved by the Invention In the conventional example described above, the plate-like fin 1 is cut and raised 5a-sa.
This is called a slit fin, and the surface thermal resistance is reduced by 40 to 50 orders of magnitude compared to a flat fin with no processing on the fin surface. However, when the fin surface is cut and raised in this way, the heat transfer coefficient in the run-up section of laminar flow is extremely high when applying the flat plate theory. It should be possible to achieve a thermal resistance value that is more than 60 times lower than the thermal resistance value of . There are various possible reasons why this theoretical value cannot be achieved, but among them, the important reasons are: ■ The ventilation resistance of the airflow passing through the cut-and-raised portions 6a to 6d is high; Since the amount of air passing through other parts increases, the thermal performance of the cut and raised parts cannot be fully utilized. ■ Effective heat transfer area decreases due to the wide presence of positive water areas. In particular, the cut-off area 6 downstream of the heat transfer tube 2 located on the upstream side of the air flow 3 covers the cut-and-raised portion 5 at the rear thereof, so the thermal resistance of these cut-and-raised portions 5 increases, increasing the average thermal resistance of the fins. let (2) Since the heat exchanger tubes 2 are arranged in a zigzag shape and the cut and raised portions 5 are provided in front or rear of the heat exchanger tubes 2, there are problems such as impeding heat flow from the heat exchanger tubes 2 and reducing fin efficiency.

Therefore, in view of the above problems, the present invention aims to: (1) equalize the flow between the heat transfer tubes, prevent the amount of air passing through the cut and raised portions from decreasing, realize flow between parallel plates, and obtain a heat transfer coefficient close to the theoretical value. Can be done.

■ Guide the flow by the phenomenon of fluid adhesion to the still area.

■ By adopting a heat transfer tube and heat transfer surface configuration that does not impede heat flow between heat transfer tubes, the above problems are solved and the thermal resistance of the fins is reduced, resulting in a compact and high-performance fin-tube heat exchanger. The purpose is to employ people.

Means for Solving the Problems In order to solve the above problems, the fin-tube heat exchanger of the present invention includes a group of plate-like fins arranged at predetermined intervals in the direction of gravity, through which gas flows; It consists of a group of heat transfer tubes that are inserted perpendicularly into a group of plate-like fins and have a fluid inside them. ,,',:) It's rough, '4 dogs are taken and arranged in a staggered manner:・ko',
, - five-way transmission, where the heat exchanger tubes partially overlap with the downstream projection plane of any of the heat exchanger tubes on the upstream side of the airflow; In between, a slit-shaped or louver-shaped cut-and-raised group is opened by cutting and raising two sides facing the airflow, and a leg row that joins the fins of the cut-and-raised group is in the normal direction of the front edge of the plate-like fin. It has a configuration in which it is provided at an angle with the

For production This means produces the following effects.

In other words, ■ Since the tube rows in each heat transfer tube group are installed with slight deviations in the airflow direction, a bridge-like or louver-like cut-and-raise can be constructed so that a part of the tubes enters the downstream part of the tubes. Therefore, there are no places near the heat exchanger tubes where the air flow velocity is high locally, and a sufficient flow rate of air can pass through the cut-and-raised tubes, so that the thermal performance of the cut-and-raised tubes can be fully utilized. ), it is possible to achieve a value sufficiently close to the theoretical heat transfer coefficient of the run-up section of a parallel plate. ■ Each heat transfer tube is installed so that it partially overlaps with one of the upstream tube projection planes of the air flow, so the flow direction of the upstream tube is changed by the downstream tube. They are attracted to the still area side, and the still area decreases. However, this phenomenon becomes more noticeable because of the provision of cut-and-raised sections between the heat transfer tube groups. In other words, the cut-and-raised part has a side part that opens in the airflow direction and a leg part that is connected to the fin, but the leg part is provided so that it enters the downstream part of the heat exchanger tube, so the airflow flows toward the cutoff area side. As a result, the still water area decreases. This will be more effective if the legs are tilted with the airflow and given an elevation angle. ■ Each row of heat transfer tubes is not installed with a significant deviation from the upstream tube when viewed from the airflow direction, so the flow of heat to the fins between the groups of heat transfer tubes is less likely to be obstructed by cutting and raising. .

This effect makes it possible to realize a finned heat exchanger with significantly higher performance than conventional ones.

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

FIG. 1 is a partial side view of a fin-tube heat exchanger according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA' in FIG. Reference numeral 11 indicates plate-shaped fins arranged in parallel at predetermined intervals. , 12 are low heat tubes, which are arranged approximately in a staggered manner with a pitch in the direction of gravity larger than the distance between adjacent heat exchanger tubes 12 in the direction of the air flow 13, and the heat exchanger tubes 12 in the direction of the air flow 13 are placed on the upstream side. Projection plane 1 of heat exchanger tubes 12a, 12c
The heat exchanger tubes 12b and 12d are configured so that only half of the heat exchanger tubes 12b and 12d overlap with each other. The heat exchanger tube 12 includes plate-shaped fins 11
It is inserted perpendicularly through a fin collar 16 provided by burring or the like, and fixed by tube expansion or brazing. Further, in the plate-shaped fin 11, a cut-and-raised group 17 having two open sides 1sa and 16b facing the airflow 13 direction between the heat exchanger tubes 12 is joined to the root-like fins 11 of this cut-and-raised group 17. The leg portions 1sa and 1sb are provided so as to form an angle with the normal direction of the front edge of the one-curve fin 11.

The effects of this embodiment are as follows. Heat exchanger tube 12
b, 12d, heat exchanger tubes 12a, 12c! Since the logging stream flows to enter the projection surface 14, the cutoff area 19 is significantly reduced. Also, at this time, the upstream heat exchanger tube 12a
, 12c and the horseshoe vortices generated due to the presence of the fins collide with the heat exchanger tubes 12b, 12d on the downstream side, and the heat exchanger tubes 12b, 12
d creates a high heat transfer zone on the surface. In this embodiment, the heat exchanger tube 12b.

The overlap between the projection surface 14 and the projection surface 12d is made to be exactly 3≦the diameter of the heat exchanger tube 12, but an effect can be obtained if there is partial overlap. However, if only this effect of reducing the positive water area 190 is considered, a reasonable effect can be expected when the overlap portion is approximately 34% to 34% of the diameter of the heat transfer tube. Furthermore, slit shape,
Or two side parts 16 with louver-shaped cut-and-raised openings.
Since a and 16b are provided offset from each other,
In the cut-and-raise on the downstream side of the airflow 13, there is always a portion located outside the temperature boundary layer created by the cut-and-raise on the upstream side of the airflow 13, and the heat transfer performance in that portion is good. In addition, since the cut and raised groups 17 are provided at an angle with the front edge of the plate-like fins 11 between the heat transfer tubes 12, the air currents flowing and supporting the cut and raised interiors have different flow directions. Slip occurs between the airflows, creating turbulence and increasing heat transfer performance. K, cut and raise legs 18a, 18b, airflow 13
Since they are provided at an angle with the direction, an airflow with a nodal component due to a secondary flow is induced from the legs 18a, 18b. This airflow has the effect of mixing the gas heat-exchanged at the cut-and-raised portion with fresh gas, and also has a nodal component to the downstream portion of the airflow 13 of the heat transfer tube 12, so that the dead area 1
9 is further reduced, and the effective heat transfer area of the plate-like fins 11 is expanded. At this time, the flow velocity of the air flow does not become faster in only a portion between the heat transfer tubes 12, a uniform air flow velocity is obtained, and the heat transfer performance of the cut and raised portion is not impaired due to a decrease in the air flow velocity. As described above, according to the fin tube type heat exchanger of the present invention, the heat transfer performance is dramatically improved compared to the conventional heat exchanger, and it becomes possible to realize a compact, high-performance, and economical heat exchanger.

Effects of the Invention As described above, the fin-tube heat exchanger of the present invention arranges the heat exchanger tubes in a substantially staggered arrangement, and the heat exchanger tubes are arranged in a substantially staggered manner in the airflow direction. A slit-shaped or louver-shaped cut-and-raise group that has a partial overlap with the surface and is opened by cutting and raising the two sides facing the airflow between the heat exchanger tubes of the plate-shaped fins. Since the leg rows that connect to the fins are arranged at an angle with the normal direction of the front edge of the plate-like fins, can sufficiently reduce the thermal resistance of ■ The flow direction of the wake from the upstream heat transfer tube is changed by the downstream heat transfer tube and flows toward the stop zone, reducing the positive water area and increasing the effective heat transfer surface. - Since each heat exchanger tube is not installed with a significant position shift when viewed from the airflow direction, the flow of heat from the heat exchanger tube to the fins and cut and raised portions is not hindered, improving fin efficiency.

As a result, heat transfer performance has improved dramatically compared to conventional methods.
It becomes possible to realize a compact, high-performance, economical heat exchanger.

[Brief explanation of the drawing]

FIG. 1 is a partial side view showing a fin-tube heat exchanger according to an embodiment of the present invention, and FIG. 2 is a line AA' in FIG. 1.
3 is a perspective view showing a conventional fin-tube heat exchanger, FIG. 4 is a partial side view showing a conventional fin-tube heat exchanger, and FIG. 6 is taken along line DD' in FIG. 4. FIG. 11... Plate fin, 12... Heat exchanger tube,
13... Airflow, 14... Projection surface, 16
a, 16b...Side part, 17...Cut and raised group, 18a, 18b...Leg part. Name of agent: Patent attorney Toshio Nakao Haga 1 person No. 3
Figure 4 Figure

Claims (2)

[Claims] (1) Consisting of a group of plate-shaped fins arranged at predetermined intervals parallel to the direction of gravity, through which gas flows, and a group of heat transfer tubes inserted at right angles to the plate-shaped fin group, through which fluid flows, The heat exchanger tube groups are arranged in a substantially staggered manner with a pitch in the gravity direction larger than the distance between the adjacent heat exchanger tubes in the airflow direction, and the heat exchanger tubes in the airflow direction are located on the upstream side of the airflow. A fin-tube heat exchanger configured to partially overlap the downstream projection surface of the heat exchanger tubes. (2) A slit-shaped or louver-shaped cut-and-raised group, which is formed by cutting and raising the two sides facing the airflow between the heat exchanger tubes, is arranged so that the leg row that joins each of the cut-and-raised fins is in front of the plate-like fin. The fin-tube heat exchanger according to claim 1, wherein the fin-tube heat exchanger is provided so as to form an angle with the normal direction of the edge.