JPS63197884A - Finned heat exchanger - Google Patents

Abstract

PURPOSE:To increase the effective thermal conducting area of fins without increasing aeration resistance in a heat exchanger to be used in an air conditioner and a refrigerator or the like by a method wherein some projections are provided on fins near thermal conducting pipes in such a manner as a part is overlapped on projected planes of the thermal conducting pipes in respect to an air flow direction. CONSTITUTION:Semi-spherical projections 15 which are smaller than the sectional area of a thermal conducting pipe 10 are arranged at front and rear surfaces of fins 12 near a downstream area of the thermal conducting pipe 10 in such a manner as their part may overlap a projected plane 14 of the thermal conducting pipe to in respect to a direction of air stream 13. A height (h) of the projection 15 is about 1/3 of a spacing (pf) of fins 12. Due to this fact, a flow separating from the surface of the thermal conducting pipe 10 is flowed to around at a rear part of the thermal conducting pipe 10 by projections 15, so that an area of a dead flow area 16 generated at a downstream flow of the thermal conducting pipe 10 is decreased. As a result of these actions, it is possible to make a substantial increase in the thermal conductivity without increasing any aeration resistance and further it is possible to make a small-sized and high performance finned heat exchanger.

Description

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

2. Description of the Related Art Conventionally, as shown in FIG. 8, this type of heat exchanger consists of heat exchanger tubes 1 connected to each other by U-bends, fins 2 made of aluminum or the like 9, and the inside of the heat exchanger tubes 1. It had a configuration in which the flowing refrigerant and the air 3 flowing between the fins 2 exchange heat. In recent years, such heat exchangers have been required to be smaller and have higher performance, but the air flow velocity between the fins is kept low from the viewpoint of noise etc. High thermal resistance. Therefore, efforts are currently being made to reduce the difference in thermal resistance from the inside of the tube by expanding the heat transfer area on the air side. However, there are physical limits to enlarging the heat transfer surface, and there are also problems in terms of economy and space saving, so it is important to reduce the thermal resistance on the air side. This has become an important issue.

FIGS. 6 and 7 show an example of a conventional heat exchanger. FIG. 6 is a plan view, and FIG. 7 is a side view. A refrigerant such as fluorocarbon is circulated inside the heat exchanger tube 4, and the heat of the refrigerant is transmitted from the heat exchanger tube 4 to the fin collar 5 and then to the fins 6. Air 7 flows from in front of the fins 6 and passes between the fins 6, and at this time, heat transmitted from the refrigerant is transferred from the surfaces of the fins 6, which have different temperatures.

This action causes continuous heat exchange between the refrigerant and the air.

Problems to be Solved by the Invention The conventional example shown in Figs. 6 and 7 is a so-called flat fin with a square tube arrangement, but this tube arrangement has a better heat transfer rate than the one in which the tubes are arranged in a grid pattern. It has a high rate and is commonly used. As shown by the dots in Figure 6,
The size of the trillion water area generated in the downstream area of the first row of heat transfer tubes 4 is 2
This is because the presence of the heat exchanger tubes 4 in the rows suppresses the increase in υ. However, even in this case, the dead area accounts for as much as 20 to 30% of the total heat transfer area. In other words, 20 to 30% of the total area is ineffective, and a large dead area also means that ventilation resistance is large, which hinders the miniaturization of heat exchangers and blowers. .

Therefore, the present invention has been developed by devising the shape of the fins.
The objective is to suppress the increase in ventilation resistance, improve the heat transfer coefficient, and obtain a compact and high-performance finned heat exchanger.

Means for Solving the Problems The technical means of the present invention for solving the above-mentioned problems is to install the cross-sectional area of the heat exchanger tubes on the fins near the heat exchanger tubes so as to partially overlap the projection plane of the heat exchanger tubes in the airflow direction. A protrusion having a small area and a height greater than or equal to the fin spacing and less than or equal to Z is provided.

For production The effect of this technical means is as follows.

In other words, as mentioned above, the protrusions are provided on the fins near the heat exchanger tubes so that they partially overlap the projection plane of the heat exchanger tubes inserted through the fins in the airflow direction, so that the flow separated from the surface of the heat exchanger tubes is The protrusions wrap around the downstream side of the heat exchanger tube, greatly suppressing the increase in the dead area generated at the downstream side of the heat exchanger tube, and greatly increasing the effective heat transfer area. FIG. 5 shows the relationship between the height h of the protrusion and the heat transfer coefficient a based on the blower power Δp-uF (Δp: ventilation resistance, up: wind speed at the front surface of the heat exchanger). It is clear that it is not effective if the height h of the protrusion is too low or too high, and considering the processability of the protrusion, K p f <: h < %pf
can be said to be optimal. (pf: fin spacing) Furthermore, since the size of the protrusion itself is smaller than the cross-sectional area of the heat exchanger tube, the ventilation resistance hardly increases. Therefore, it is possible to increase the effective heat transfer area while suppressing an increase in ventilation resistance, and the heat transfer characteristics of the heat exchanger are greatly improved.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 is a plan view of a finned heat exchanger according to an embodiment of the present invention, and FIG. 2 is a side view of FIG. 1. 1° are heat transfer tubes arranged in a staggered manner, inside of which a refrigerant circulates. The heat possessed by the refrigerant is sequentially transmitted from the heat transfer tube 1° to the fin collar 11 and the fins 12, and exchanges heat with the air flowing in the airflow direction 13. Then, the airflow direction 1 of the heat exchanger tube 1o
Hemispherical protrusions 15 smaller than the cross-sectional area of the heat exchanger tubes 1o are provided on the front and back surfaces of the fins 12 in the vicinity of the trailing region of the heat exchanger tubes 1o so as to partially overlap on the projection plane 14 for the fins 3.

In addition, the height h of the hemispherical protrusion 15 is the interval pf of the fins 12.
It is about % of

Next, the operation of the configuration of this embodiment will be explained.

Since the hemispherical protrusions 16 are provided near the heat exchanger tubes 10 so as to partially overlap the projection plane 14 of the heat exchanger tubes 10 in the airflow direction 13, the flow separated from the surface of the heat exchanger tubes 1o is further enhanced by the hemispherical protrusions 15. Since the water flows around the back of the heat exchanger tubes 1o, the area of the dead zone 16 that occurs in the downstream area of the heat exchanger tubes 10 is greatly reduced. In addition, since the hemispherical protrusions 15 are provided in pairs on the front and back surfaces of the fins 12 so as to be almost adjacent to each other, the size of the dead area 16 of the heat exchanger tube 10 is reduced on the front and back surfaces of the fins 12. Decrease.

Therefore, since the area contributing to heat transfer increases significantly, (
In particular, the dead area 16 of the second row of heat exchanger tubes 1o is almost the same size as the dead area of the first row in the airflow direction 13), and the surface heat transfer coefficient of the fins 12 is greatly improved. Since the hemispherical protrusion 16 is smaller than the cross-sectional area of the heat exchanger tube 10 and the height h is less than % of the fin spacing pf, the dead area generated downstream of the hemispherical protrusion 16 is very small. Therefore, there is almost no increase in ventilation resistance due to the installation of the hemispherical projections 16.

As a result of these effects, according to this embodiment, the heat transfer coefficient can be greatly improved, and the finned heat exchanger can be made smaller and have higher performance.

Next, other embodiments of the present invention will be described.

3 and 4 show another embodiment of the present invention, in which FIG. 3 is a plan view and FIG. 4 is a side view of FIG. 3. Reference numeral 2o denotes a heat transfer tube, in which a refrigerant circulates, and the heat of the refrigerant is sequentially transmitted from the heat transfer tube 20 to the fin collars 21 and fins 22. On the other hand, when the airflow flowing in the airflow direction 23 passes between the fins 22, heat transferred from the refrigerant is indirectly exchanged via the surface in contact with the air.

Heat exchanger tubes 2ob and 20c are heat exchanger tubes 2 installed on the airflow side.
The device is arranged so that it overlaps only half of the projection plane of 0a. Then, the fins 2 at the rear of the heat exchanger tubes 2o are arranged so that the fins 2 at the rear of the heat exchanger tubes 2o partially overlap on the projection plane of each of the heat exchanger tubes 2o with respect to the airflow direction 23.
Airfoil-shaped protrusions 24 smaller than the cross-sectional area of the heat exchanger tubes 20 are provided on the fins 22 on the front and back surfaces of the heat exchanger tube 20. In addition, the wing-shaped process 2
The height h of 4 is about % of the fin spacing pf.

Next, the operation of the configuration of this embodiment will be explained. In this embodiment, the heat exchanger tubes 20 are not arranged in a staggered manner, and the airfoil-shaped protrusions 24 are configured in an airfoil shape.

Therefore, in addition to the effects described in the first embodiment, the following effects occur. That is, the airfoil projections 24 cause the flow separated from the heat exchanger tubes 2o to flow directly into the downstream region of the heat exchanger tubes 2o, thereby greatly reducing the dead area 25 of the heat exchanger tubes 2o. Furthermore, a secondary flow (vortex) as shown by the arrow 26 is generated by the flow along the airfoil protrusion 24 and the flow over the airfoil protrusion 24, which stirs a part of the main flow and reduces the heat transfer coefficient between the airflow and the surface of the fin 22. will improve. Furthermore, since the heat exchanger tubes 20a, 20b, and 20c are arranged in rows, the heat flow between the heat exchanger tube groups is not obstructed.
The fin efficiency is also high, and the heat exchanger tubes 2 are perpendicular to the airflow direction 23.
Between 0 and 0, the flow becomes a rectangular flow path and a high surface heat transfer coefficient is obtained.

Effects of the Invention As described above, the present invention comprises fins that are arranged in parallel at regular intervals and through which air flows, and heat transfer tubes that are inserted at right angles to the fins and through which fluid flows. Projection of heat tubes in the airflow direction: Protrusions with an area smaller than the cross-sectional area of the heat exchanger tubes and a height not less than % of the fin spacing are provided on the fins near the heat exchanger tubes so that they partially overlap on the color painting. Since it is a heat exchanger with fins, the dead area area downstream of the heat transfer tubes can be significantly reduced without increasing ventilation resistance, increasing the effective heat transfer area. Therefore, the heat transfer coefficient of the fins is greatly improved, and a compact and high-performance finned heat exchanger can be realized.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a finned heat exchanger according to an embodiment of the present invention, FIG. 2 is a side view of the same, and FIG. 3 is a plan view of a finned heat exchanger according to another embodiment of the present invention. Figure 4 is the same side view;
FIG. 5 is a characteristic diagram of the present invention, FIG. 6 is a plan view of a conventional finned heat exchanger, FIG. 7 is a side view thereof, and FIG. 8 is a perspective view thereof. 10.20.20a, 20b, 20cm------
Heat exchanger tube, 12, 22...Fin, 13, 23
...Airflow direction, 14...Projection plane, 15
... Hemispherical process, 24... Pterygoid process. Name of agent: Patent attorney Toshio Nakao and one other person lθ
---Pull to IyunR [12- Finno 3 ---Kiu Seri ξ direction [Bow 14- Setsai Painting Figure 2 20a, 20b, ZOc-!云M'tzz - Fore 23 - Air flow direction Z4 - Airfoil projection Figure 3 Figure 5 "A" Height of the protrusion Curse Figure 6 Figure 7 Figure 8

Claims (2)

[Claims] (1) Consisting of fins arranged in parallel at regular intervals, through which air flows, and heat transfer tubes inserted at right angles to the fins, through which fluid flows, the projection surface of the heat transfer tubes with respect to the air flow direction. A fin heating system in which a protrusion is provided on the fin near the heat exchanger tube so that it partially overlaps the fin, the area is smaller than the cross-sectional area of the heat exchanger tube, and the height is 1/4 or more and 1/2 or less of the fin spacing. exchanger. (2) The heat exchanger with fins according to claim 1, wherein projections are provided on the front and back surfaces of the fins.