JPS6183893A - Heat exchanger having fin - Google Patents

Abstract

PURPOSE:To improve the gas side heat transmission efficiency to provide a compact, high performance device by reducing the area of dead water in a downstream part of a heat transmission pipe, and by reducing the thickness of the temperature boundary layer on the fin heating surface. CONSTITUTION:As two sides 17a, 17b of a slit-like cut and raised parts 14a-14c are at an angle relative to the airflow, the airflow 23 enters into the downstream part of the airflow in heat transmission pipe, and so, the area of dead water in the downstream part of the airflow in the heat transmission pipe is reduced. The airflow 24 overflowing the side 17a moves like clinging to the central part 19 and flat fin 10 to disturb the temperature boundary layer grown on their surfaces so as to reduce the thickness of the boundary layer. When the airflow 25 flows out of an opening 20, it mixes with the airflow moving on the central part 19. After overflowing the side 17b, a turning component is induced in the airflow 25 just like in the airflow 24 to reduce the thickness of the temperature boundary layer grown on the flat fin 10 to reduce the dead water area. By the action of the turning component of the airflow 26 in addition to said airflow 25, the mixing effect of the airflows and the leading edge effect of boundary layer, the gas side heat transmission rate of the fin is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a finned heat exchanger for gas-gas-liquid two-phase flow (or liquid), which is widely used in evaporators, condensers, etc. in the field of air conditioning equipment. It is something.

Structure of the conventional example and its problems As shown in the perspective view of FIG.
It consists of a group of heat transfer tubes 2 inserted perpendicularly to the fins, and gas flows between the fins in the direction of the arrow 3 to exchange heat with the fluid inside the tubes. The flow of gas between the fins of the fin group 1 is as shown in FIG. 2, and dead water 8 is generated as shown by diagonal lines in the air flow downstream of the heat transfer tube 5 and the fin collar 60 provided around it. Therefore, the gas-side heat transfer coefficient of the fins in this dead zone is significantly lowered, resulting in poor heat transfer performance.

In addition, as shown by the shaded area 9 in FIG. 3, the temperature boundary layer on the heat transfer surface of the flat fin 4 increases in thickness as the distance from the airflow upstream end surface (fin leading edge) of the flat fin 4 increases. increases, and as a result, the gas side heat transfer coefficient decreases significantly as the distance from the leading edge of the fin increases, resulting in a disadvantage of poor heat transfer performance.

Purpose of the Invention The present invention eliminates the above-mentioned drawbacks of the conventional finned heat exchanger. In particular, it completely reduces the dead area at the downstream part of the heat transfer tube, and also reduces the thickness of the temperature boundary layer on the fin heat transfer surface. The objective is to realize a significant improvement in the gas-side heat transfer coefficient by reducing , and to achieve a smaller size and higher performance of a finned heat exchanger.

Structure of the Invention The finned heat exchanger of the present invention is composed of a group of flat plate fins arranged in parallel at predetermined intervals, and heat transfer tubes inserted perpendicularly into the group of flat plate fins and through which a fluid flows. In the upstream region of the airflow, that is, the region between the straight line connecting the centers of the heat exchanger tubes and the fin end face (fin leading edge) on the upstream side of the airflow,
A plurality of slit-like cuts are provided on the Ai flat plate at an angle in the flow direction of the airflow, and the slit-like cuts are provided on the airflow downstream region between the heat transfer tubes, that is, in the airflow downstream region from the straight line connecting the centers of the heat transfer tubes. A plurality of slit-like cut-and-raised parts B are installed on the flat plate fins so as to be inclined in the opposite direction to the raised slit-like raised part A, and a slit-shaped cut-and-raised part C or a vertical wall is provided on the downstream side of the slit-shaped cut and raised parts B to direct the flow of airflow. In the case where the slit-shaped cut-and-raised portions A, B, and C are provided at an angle, the central portions of the slit-like cut-and-raised portions A, B, and C are lower than the two side portions of the cut-and-raised portions that connect to the flat plate fin, and the cut-and-raised central portions are An opening S is provided.

DESCRIPTION OF EMBODIMENTS A finned heat exchanger according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 4a is a plan view of a flat fin according to an embodiment of the present invention, and FIG. 4 is a sectional view taken along line AA' of FIG. 4a. Also, Figures 6a and b are respectively S'J of Figure 4a.
y )-shaped cut and raised sectional view on the BB' plane and a sectional view on the CC' plane.

Heat transfer tubes 12 are inserted into fin collar portions 11 that are barred at regular intervals on the flat plate fins 10, and the airflow flows in the direction of the arrow 13. In the airflow upstream region between the heat transfer tubes of the flat plate fin 1o (the region shown as region 1 in FIG. 4a), there is a slit-shaped cut and raised A (
14a to 14C) are installed, and the slit-like cut and raised A (14a to 14C) is installed in the downstream region of the airflow between the heat transfer tubes (indicated by region ■ in FIG. 4a) with respect to the airflow 13 in the opposite direction. Slit-shaped cut-and-raise B (16a).

15b) is installed. These slit-like cut-and-raised parts A (14a to 14c) and B (15a).

15b), as shown in FIG. It has a shape with .

In addition, the slit-shaped cut and raised B (15a).

Standing walls 16a and 16b'iz are provided on the downstream side of the airflow 15b) so as to be inclined in the flow direction of the airflow 13, and the standing wall 16a is provided.

An opening 21'Jr is provided on the downstream side of the airflow of 18b.

Next, the functions and effects will be explained with reference to FIG. 6, which shows the state of airflow in the fins of the present invention.

In the airflow upstream region between the heat transfer tubes, slit-like cut-and-raised A (14a-14C) are installed at an angle with the airflow 13.
The airflow that collides with C) or the airflow that flows near the cut and raised portion will be in a flow state as shown in FIG. The airflow in the vicinity of the slit-like cut and raised portions A (14a to 14C) can be roughly divided into the following 40 types of airflow, and the functions and effects of each will be described.

(1) Slit-shaped cut and raise A (14a to 14c)
Since the two sides 17a and 17b are inclined to the airflow, the airflow 23 along the surface facing the airflow 13 at the two sides 17a and 17b of the heat exchanger tube is water bodies). Therefore, the dead area in the air flow downstream part of the heat exchanger tube is smaller than that of conventional flat fins, and the heat transfer coefficient in the gas flow downstream part of the heat exchanger tube becomes higher.

(The airflow 24 that crosses the side part 17a has a swirling component after passing over the side part 17a because the side part is inclined with respect to the airflow 13 as described above.

Further, since the height of the side portions 17a from the flat fins 10 is greater than the height of the cut and raised central portion 19, the airflow 24 flows so as to adhere to the central portion 19 and further to the flat fins 10 again. When the airflow 24 flows in this way, it disturbs the temperature boundary layer that has developed on the surface of the flat plate fin 1o and the raised central part 19, and reduces the thickness of the boundary layer, resulting in a significant improvement in the heat transfer coefficient on the gas side of the fin. is realized. −
(3) The airflow 25 flowing between the flat fin 10 and the central part 190 of the slit-like cut-and-raised part is influenced by the slit-like cut-and-raised part installed on the lower similar flat fin adjacent to this flat fin, and It flows out from the opening 20 provided in the portion 19, crosses the side portion 17b via the two side connecting portions 18, and flows to the downstream side. Airflow 25 is connected to opening 2
When flowing out from 0, it mixes with the airflow that has flowed above the central portion 19, and a so-called airflow mixing effect is expected. There is also a boundary layer leading edge effect at the center of the cut-up on the downstream side of the airflow of the opening 2o. After getting over the side part 1γb1, airflow 2
Similar to the air flow 24, a swirling component is induced in the airflow 6, and this swirling component acts to reduce the thickness of the temperature boundary layer developed in the flat fin 1o. Furthermore, slit-shaped cut and raised A
In (14a, 14b), the airflow 26 as well as the airflow 24 flows in the direction of the downstream part of the heat exchanger tube like the airflow 23, so it is effective in reducing the dead area.As described above, the swirling component of the airflow 25 The heat transfer coefficient on the gas side of the fins is improved due to the effect of air flow, the mixing effect of the air flow, and the leading edge effect of the boundary layer.

(4) In addition to the above-mentioned airflow 23, the flow flowing near the airflow upstream side end surfaces of the second side sides 17a and 17b includes the second side side 1
There is an airflow 26 on the back side of the surface facing the airflow 13 of 7a, 17b. This airflow 26, two side parts 17a,
The airflow has a swirling component under the influence of the upstream end face of the airflow 17b. The swirling component of the airflow 26 is the same as the above-mentioned airflow 25.
26, the thickness of the temperature boundary layer of the flat plate fin 10 is reduced, so the heat transfer coefficient on the gas side of the fin is improved. Cut and raise A (14z, ~14C) and tilt the airflow 13 in the opposite direction to raise the slit 9 and raise B (15
a, 15b) are installed, and their functions and effects are as follows.

The shape of the slit-like cut-and-raise B (16a, 15b) is the same as the slit-like cut-and-raise A (14a to 14C), so the slit-like cut and raise B (16a).

The action and effect of 15b) are as follows:
14C), but cut and raise B (15a
, 15b) are collided with airflows with swirling components induced by cut-and-raise A (14a to 14C), so airflows with even more diverse swirling components are induced, which significantly reduces the thickness of the temperature boundary layer. , the gas side heat transfer coefficient of the fins is significantly improved.

Next, the function and effect of the standing walls 16a, 16b installed on the airflow downstream side of the cut and raised B (15a, 15b) will be explained. The vertical walls 16a and 16b are also cut and raised A (14
a to 14c), B (15a.

Similar to 15b), since they are installed to be inclined in the flow direction of the airflow 13, the airflow induced by the vertical walls 16a and 16b can be roughly classified into the following three types.

(1) Similar to the airflow 23 described above, the airflow 27 along the vertical walls 16a and 16b is a flow that is deflected toward the downstream part of the heat exchanger tube, so it is effective in reducing dead areas, and improves the heat transfer performance of the fins.

(2) When the airflow 28 that overcomes the vertical walls 16a, 1 abff and overcomes the vertical walls 16a and 16b, a swirling component is induced when the airflow 28 overcomes the vertical walls 16a and 16b. Improve heat transfer coefficient. Furthermore, since the airflow 28 flows so as to reattach to the flat plate fin 1o, the heat transfer coefficient on the gas side of the fin at the reattachment point of the airflow 28 is large.

(3) When the opening 21 is installed on the airflow downstream side of the vertical walls 16a, 16b, the airflow 2
9 flows. A swirling component is also induced in this airflow 29, and in addition to reducing the thickness of the temperature boundary layer on the flat plate fin and improving the gas side heat transfer coefficient, the leading edge effect of the boundary layer at the opening 21 is also induced. Yes, the improvement in the gas side heat transfer coefficient of the flat fin is remarkable.

Effects of the Invention As described above, the finned heat exchanger of the present invention has the effect of reducing the dead zone in the air flow trailing part of the heat transfer tube, and reducing the thickness of the temperature boundary layer on the flat plate fins due to the swirling component of the air flow. By utilizing the gas mixing effect and the leading edge effect of the boundary layer, the gas side heat transfer coefficient of flat fins is significantly improved, and a finned heat exchanger is made smaller and has higher performance.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional heat exchanger with fins, FIGS. 2 and 3 are explanatory diagrams of the state of air flow in the flat fins in FIG. 1, and FIG. 4a is an embodiment of the present invention. FIG. 6 is a sectional view taken along the CC' plane of the fins in the example heat exchanger with fins, and is an explanatory diagram of the state of airflow in the fins of FIG. 4. 10... Flat fin, 11... Fin collar, 12... Heat exchanger tube, 13... Air flow, 14... Pickpocket. T-shaped cut and raised, 15... Slit-shaped cut and raised, 16a, 16b... Standing wall, 17...
Side part of slit-shaped cut and raised part, 18... 2 side connecting part, 19...... Slit-shaped cut and raised central part, 20... Central opening, 21... ... Opening of standing wall 16, 22 ... Flat plate fin opening, 2
3-29...Airflow. Name of agent: Patent attorney Toshio Nakao and 1 other person
4 Figure (O-) Figure 5 (Grade (b)

Claims (4)

[Claims] (1) Consisting of flat plate fins that are arranged in parallel at regular intervals and through which air flows, and heat transfer tubes that are inserted perpendicularly into the flat plate fins and through which fluid flows, A plurality of slit-like cut-and-raised portions A provided in an upstream region of the airflow so as to be inclined in the flow direction of the airflow, and a plurality of slit-like cut-and-raised portions A that are provided in a downstream region of the airflow in a direction opposite to the slit-like cut-and-raised portions A in the flow direction of the airflow. A heat exchanger with fins in which a slit-like cut and raised B is provided at an angle, and the center portion of the cut and raised A and B is lower than the two side portions of the cut and raised A and B that are connected to the flat plate fin. . (2) The central part of the slit-shaped cut-and-raised C, which is provided on the downstream side of the airflow of the slit-shaped cut-and-raised B and inclined in the flow direction of the airflow, is lower than the two side parts connected to the flat plate fin. A finned heat exchanger according to claim 1. (3) The finned heat exchanger according to claim 2, wherein an opening is provided in the center of the cut and raised slits A, B, and C. (4) The finned heat exchanger according to claim 2, wherein a standing wall D is provided in place of the slit-like cut and raised portion C.