JPS6141893A - Heat exchanger with fin - Google Patents

Abstract

PURPOSE:To increase the heat transfer rate on the gas side, by providing a plurality of raisings to a fin which is slanted in the flowing direction of air flow in the upstream side of a heat transfer pipe, and the raisings slanted to the reverse direction, in the downstream side, respectively. CONSTITUTION:The raisings 14a-14c provided in the upstream side of an air flow among heat transfer pipes 12 are slanted in the direction 13 of an air flow, so that an air flow 19 is produced by the air collided against the raising 14a. The dead water areas 16 and 17 around fins are made small by the effect of an air flow 18. An air flow 20 which crosses over the raisings 14 is deviated and is turned to the direction to adhere to flat fins 10 again, interfered by an air flow 21 which rolls up the air flow 20 into the flow on the side of the after flow of a raising 14c, produces flows 22 and 24 having swirling component parts, respectively. The flows 22 and 24 collide against a raising 15b in the downstream area of an air flow among heat transfer pipes 12, deviating, interfered by an air flow 23, producing air flows 25 and 26, having stronger swirling component parts. A boundary layer of temperature is disturbed by those flows 25 and 26, so that the thickness of a layer is decreased and the heat transfer rate on the gas side can be increased.

Description

Detailed Description of the Invention: Industrial Application Field The present invention relates to a heat exchanger with fins for gas-gas-liquid two-phase flow (or liquid calculation), which is widely used in evaporators, condensers, etc. in the field of air conditioning equipment. It is related to.

Structure of the conventional example and its problems As shown in the perspective view of Fig. 1, the conventional heat exchanger has a group of fins 1 arranged in parallel at regular intervals and a group of heat exchanger tubes 2 inserted perpendicularly to the group of fins 1. The gas flows between the fins in the three directions indicated by the arrows and exchanges heat with the fluid inside the tube. The flow of gas between the fins of fin group 1 is as shown in Figure 2.
Since dead areas 7 and 8 shown by diagonal lines are formed in the downstream portion of the heat transfer tube, the heat transfer coefficient on the gas side in these dead areas is significantly reduced, resulting in poor heat transfer performance.

Furthermore, 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 in proportion to the square root of the distance from the upstream end surface of the flat fin 4. death,
Therefore, the heat transfer coefficient on the gas side significantly decreases as the distance from the end face on the upstream side of the airflow increases, resulting in a drawback of poor heat transfer performance.

Purpose of the Invention The present invention eliminates the above-mentioned drawbacks of the conventional technology, and in particular reduces the dead zone downstream of the heat transfer tube and the thickness of the temperature boundary layer on the heat transfer surface of the fin, thereby improving the heat transfer coefficient on the gas side. The objective is to achieve a smaller size and higher performance of a finned heat exchanger by realizing a significant improvement in the fin heat exchanger.

Structure of the Invention The finned heat exchanger of the present invention is composed of flat plate fins arranged in parallel at regular intervals, through which gas flows, and heat transfer tubes inserted perpendicularly to the flat plate fins, through which fluid flows. The upstream region of the airflow between the heat exchanger tubes, that is, the region between the straight line connecting the centers of the heat exchanger tubes and the leading edge of the fin on the upstream side of the airflow, is inclined with respect to the flow direction of the airflow (at an angle from the normal line of the leading edge of the fin). A plurality of cut-and-raised pieces are provided on the flat fin, and in the downstream region of the airflow between the heat transfer tubes, that is, the region between the straight line connecting the centers of the heat-transfer tubes and the trailing edge of the fin on the downstream side of the airflow, airflow is directed in the opposite direction to the cut-and-raised pieces. A cut and raised piece that is inclined with respect to the flow direction of the fin (the angle is opposite to the angle between the normal line of the cut and raised piece and the leading edge of the fin), and the end face on the upstream side of the airflow is aligned with the cut and raised piece. A plurality of fins are installed on a flat plate fin so that they are at different levels from the airflow side end surface of the fin. In addition, a plurality of cut and raised pieces are placed on the downstream side of the heat transfer tubes in the downstream area between the heat transfer tubes, slanting with the flow direction of the airflow and forming a "C" shape when viewed from the upstream side of the airflow. The above-mentioned cut-and-raised piece is placed on the flat fin by shifting it to the downstream side of the airflow.

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. 4(,) is a plan view of a flat plate fin according to an embodiment of the present invention, FIG. 4((9) is AA' in FIG.
FIG. Further, FIG. 5 is a plan view of a flat plate fin according to another embodiment of the present invention, in which a heat transfer tube 12 is inserted into a fin collar part 11 which is burred at regular intervals on a flat plate fin 1o, in the direction of an arrow 13. In the upstream region of the airflow between the heat transfer tubes (region I in Fig. 4), there are cut and raised sections 146 to 146 inclined with respect to the flow direction 13 of the airflow.
A plurality of fins 140 are installed on the flat plate fin 1o, and in the downstream region of the airflow between the heat transfer tubes (region marked with ■ in FIG. 4), the above-mentioned cut-and-raised portions 14a to 14C are provided with the airflow direction 13 in which direction. Slanted cut and raised 16a.

1sb, its airflow upstream end face is cut and raised 146.
A plurality of fins are installed on the flat plate fin 1o so as to be at different levels from the end face on the downstream side of the airflow of the fins 14c.

In addition, in another embodiment of the present invention shown in FIG. 5, the downstream part of the heat transfer tube is inclined with respect to the flow direction of the airflow, and is cut and raised to form a "C" shape when viewed from the upstream side of the airflow. 28a, 28
b is placed on the flat plate fin, shifted to the downstream side of the airflow from the cut and raised portions 16a and 15b installed in the downstream region of the airflow between the heat transfer tubes.

Next, the action and effects will be explained. First, in the airflow upstream region between the heat exchanger tubes (region 1 in FIG. 4), cut and raised 14a to 1
4c is provided at an angle with respect to the airflow direction 13,
A flow 19 that is deflected toward the heat exchanger tube is induced in the airflow that collides with the cut and raised portion 14a. This flow 19 is a flow toward the dead area (the dead area shown in 7.8 in Figure 2) that occurs in the conventional flat fin, and due to the action with the airflow 18, the dead area in the fin of the present invention is as shown in Figure 6. The shaded area 16.
17, it is very small compared to the conventional fin dead area shown by the dotted line. In addition, there is a cut and raise 28 at the downstream part of the heat exchanger tube.
If a heat exchanger tube is provided, the dead area at the downstream part of the heat transfer tube becomes even smaller. Therefore, the gas side heat transfer coefficient, especially in the downstream portion of the heat exchanger tube, is greater than that of conventional flat fins, and heat transfer performance is improved.

Next, FIG. 7 shows the state of air flow in the fins of the present invention. The airflow 2o that overcomes the cut and raised 14 is deflected in the direction of adhering to the flat plate fin 10 again, and this flow passes between the cut and raised 140 and interferes with the airflow 21 flowing into the downstream side of the cut and raised 14 &~14C. As a result, flows 22 and 24 having swirling components are generated. Then, the flow 22,24 having the swirling component is deflected by colliding with the cut-and-raised portions 14a to 14c and the cut-and-raised portions 1sa and 1esb having different installation angles in the downstream region of the airflow between the heat transfer tubes, and The cut and raised portions 15a and 15 interfere with the airflow 23 that has passed between the cut and raised portions 144 to 14c.
Airflow with a stronger swirling component in the wake of b 25.2
Generate 6. The airflow having such a strong swirling component disturbs the temperature boundary layer on the flat fin heat transfer surface and reduces the thickness of the boundary layer, thereby realizing a significant improvement in the gas side heat transfer coefficient. In addition, the airflow having the above-mentioned swirling component has the effect of strengthening the horseshoe expansion that is generated around the heat transfer tube and improves the heat transfer performance, so further improvement in the heat transfer performance of the fins can be expected.

Furthermore, as shown in FIG. 8, the airflow flowing between the fins cuts and raises the fins 14a to 14G and 15a.

When colliding with fin 16b, in addition to the airflow 2o that overcomes the cut-and-raised part, an airflow 27 is also generated that flows through the openings of the cut-and-raised part between adjacent fins, and this airflow 27 has a mixing effect of the flow and This creates a boundary layer leading edge effect at the opening and reduces the thickness of the temperature boundary layer on the fin heat transfer surface, which significantly improves the gas side heat transfer coefficient and improves the heat transfer performance of the finned heat exchanger. improve.

Effects of the Invention As described above, the finned heat exchanger of the present invention deflects the airflow around the heat transfer tubes, induces a strong swirling component in the airflow, and prevents the mixing of the airflow between the fins. (by promoting
Since the thickness of the temperature boundary layer on the fin heat transfer surface is reduced, the heat transfer coefficient on the gas side of the fins is significantly improved, and a finned heat exchanger can be made smaller and have higher performance.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional finned heat exchanger, FIGS. 2 and 3 are explanatory diagrams of the state of air flow in the flat fins in FIG. 1, and FIG. 40 is an embodiment of the present invention. FIG. 4(b) is a plan view of the fins in a finned heat exchanger according to another embodiment of the present invention, FIG. Top view of the fin,
FIGS. 6, 7, and 8 are explanatory diagrams of the state of airflow in the fins of FIG. 4. 1Q...Flat fin, 11...Fin collar, 12...Heat transfer tube, 13...Air flow, 14...Between heat transfer tubes Cutting and raising the airflow upstream region, 16... Cutting and raising the airflow downstream region between heat transfer tubes, 15.17... Dead area, 18-2... Between fins Airflow at 28...Cut up 0 Agent's name Patent attorney Satoshi Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 (α2 Figure 5 Figure 6

Claims (2)

[Claims] (1) A group of fins arranged in parallel at predetermined intervals, a heat exchanger tube passing through the fin group, and a plurality of fins provided on the fin at an angle to the flow direction of the airflow in an upstream region of the airflow with respect to the heat exchanger tube. A heat exchanger with fins, characterized in that a cut-and-raised piece A is provided on the fin, and a cut-and-raised piece B is provided on the fin and inclined in the opposite direction to the cut-and-raised piece A in a downstream region with respect to the heat exchanger tube. . (2) The finned heat exchanger according to claim 1, characterized in that the cut-and-raised piece C is provided on the downstream side of the cut-and-raised piece B with respect to the airflow.