JPS5899691A - Finned heat exchanger - Google Patents

Abstract

PURPOSE:To enhance heat-transmitting efficiency, by a method wherein substantially circular arch form projections faced to an air flow are provided on fin surfaces at gap parts provided in the row direction around a group of heat- transmitting pipes, and a plurality of projections perpendicular to the flowing-in direction of the air flow are provided on fin surfaces at gap parts provided in the stage direction around adjacent heat-transmitting pipes. CONSTITUTION:The heat-transmitting pipes 2 are passed through fin collar parts 5 formed by burring in flat plate fins 1 at regular intervals. At the periphery of each of the fin collar parts 5 of the fins 1 at the gap parts provided in the row direction of the pipes 2, the substantially circular arch form projections 6, 7 coaxial with the fin collar part 5 and having a diameter larger than that of the collar part 5 are provided on the upstream side and the downstream side in respect of the air flow. On the other hand, on the surfaces of the fins 1 at the gap parts between the pipes 2 adjacent to each other in the stage direction, the projections 8, 9 perpendicular to the flowing-in direction indicated by blank arrows are provided.

Description

[Detailed Description of the Invention] In recent years, with the reduction in noise from air conditioners, there has been a growing tendency to design heat exchangers with front wind speeds of 1"1/s or less. Improving device performance is a major challenge.

The present invention proposes a configuration of a heat exchanger that meets the above-mentioned demands, and in particular, reduces the temperature boundary layer of the stop zone downstream of the heat transfer tube and the heat transfer surface by 2. This aims to significantly improve the heat transfer coefficient on the air side heat transfer surface.

Conventionally, this type of heat exchanger has a group of flat plate fins 1 arranged in parallel at regular intervals and two groups of heat transfer tubes inserted at right angles to the fin group 1, as shown in FIG. It flows between the fins 1 in the direction of the white arrow and exchanges heat with the fluid inside the pipe. As shown in Figure 2, the thermal fluid characteristics around the heat exchanger tube 2 between the fins 1 are as follows: When a low wind speed airflow flows through the heat exchanger tube 2 in the direction of the white arrow, When the angle θ is ±70 to 8 g, the flow separates, and a positive zone 3 shown by diagonal lines is generated at the downstream part of the heat exchanger tube 2. As a result, the air side heat transfer coefficient in this still zone 3 decreases significantly. It had the disadvantage of low heat transfer performance as a heat exchanger.

Furthermore, as shown in FIG. 2C, the thickness of the temperature boundary layer 4 on the heat transfer surface of the Tween 1 increases in proportion to the square root of the distance from the airflow inlet. The heat exchange rate significantly decreases as the distance from the air flow inlet increases, and the heat transfer efficiency as a heat exchanger is low.

The present invention considers the above-mentioned problems and solves them. As a solution to this, the present invention includes a group of fins arranged in parallel at regular intervals, through which air flows, and a group of heat transfer tubes inserted at right angles to the group of fins, through which fluid flows. A substantially arc-shaped protrusion facing the airflow is provided on the fin surface in the gap in the row direction around the group,
A plurality of protrusions are provided perpendicularly to the inflow direction of the airflow on the fin surfaces of the gaps in the direction of adjacent steps.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1a and 1b.

In the present invention, the heat transfer tubes 2 are inserted into the fin collar portions 5 which are barred at regular intervals on the flat plate fins 1, and the fins 1 are inserted in the air flow direction flowing in the direction of the white arrow, that is, in the gap in the direction of the heat transfer tubes 20 rows. Approximately arc-shaped protrusions 6 and 7, which are concentric with the fin collar part and have a diameter smaller than the diameter of the fin collar part 6, are provided around each fin collar part 6 on the upstream side facing the airflow.

It is installed on the downstream side. That is, the protrusions 6 and 7 are connected to the heat exchanger tube 2
In the row direction, the nearest fin collar part 5 is sandwiched to form a square shape, and the length l in the row direction is the length l of the fin collar part 5.
It is larger than the diameter. In addition, as is clear from the Moum cross-sectional view shown in Figure 1, there is a fin 1 surface in the gap between heat exchanger tubes 2 adjacent to each other in the direction perpendicular to the airflow flowing in the direction of the white arrow, that is, in the step direction of the heat exchanger tubes 2. , protrusions 8 and 9 are provided that are perpendicular to the airflow flowing in the direction of the white seal.

Having such a configuration has the following effects.

When airflow flows in the direction of the white arrow in the finned heat exchanger composed of fins 1 and heat exchanger tubes 2, the airflow around the heat exchanger tubes 2 collides with the heat exchanger tubes 2, and then reaches the protrusion 6 on the upstream side facing the airflow. This prevents the air from spreading away from the heat exchanger tubes 2, and due to the protrusion 7 facing the downstream airflow which has the effect of damming the flow, the airflow also enters the downstream area of the heat exchanger tubes 2, reducing the stopping area. Therefore, even in the downstream region of the heat exchanger tubes 2, sufficient heat exchange between the heat exchanger tubes 2 and the airflow can be performed, so that the heat transfer performance of the heat exchanger is significantly improved.

In addition, the airflow flowing between the fins 1 in the direction of the white arrow is
This is disturbed by the protrusions 8 and 9 provided on the fins 1 in the gaps between the heat exchanger tubes 2 in the step direction, where the area through which the airflow passes decreases. Such turbulence in the mainstream also affects the surface of the heat exchanger tube 2, and
The thickness of the temperature boundary layer of the airflow on the surface of the fin 1 is also intermittently thinned in the airflow direction, so that the heat exchange performance is further improved.

Furthermore, when the heat exchanger is used as a cooler, condensed water generated near the heat exchanger tubes 2 on the fin 1 surface falls and flows along the protrusions 6, 7, but the protrusions 6.7 Since the condensed water has a substantially circular arc shape concentric with the fin collar portion 6 into which the heat transfer tube 2 is inserted, the condensed water flows and falls toward the point where the angle θ from the stagnation point on the surface of the heat transfer tube 2 is 90. No use, heat transfer tube 2
At the same time, condensed water adhering to the periphery of the protrusion 8.9 formed on the surface of the fin 1 in the gap in the step direction also flows and falls.

Therefore, even when used as a cooler, the substantially arcuate projections 6 and 7 formed around the heat transfer tube 2 and the projection 8 formed on the surface of the fin 1 in the gap in the direction of the second stage of the heat transfer tube.
, 9 can be maintained, and the heat transfer performance can be significantly improved.

In addition, approximately arc-shaped projection 6. Since the projections 8 and 9 are symmetrical in shape with respect to the direction line B-B of the central axis of the heat exchanger tube 2, the heat exchanger is sometimes installed in the opposite direction, causing the airflow to become white. Even if the airflow flows from the direction opposite to the direction of the blank arrow, the heat transfer performance is the same as when the airflow flows from the forward direction (the direction of the solid white line), so errors in installation can be eliminated.As described above, the present invention A group of fins arranged in parallel at regular intervals, through which air flows, and a group of heat transfer tubes inserted at right angles to the group of fins, through which fluid flows, and gaps in the column direction around the group of heat transfer tubes. A substantially arc-shaped protrusion facing the airflow is provided on the fin surface of the fin, and a plurality of protrusions are provided perpendicularly to the inflow direction of the airflow on the fin surface of the gap in the direction of adjacent steps. As a result, the stopping area behind the heat transfer tube becomes smaller and the temperature boundary layer of the airflow on the fin surface becomes thinner, allowing sufficient heat exchange between the heat transfer surface and the airflow, greatly improving the heat transfer performance of the heat exchanger. do. Furthermore, when used as a cooler, airflow flows without being affected by condensed water, so heat transfer performance is greatly improved.

Furthermore, since the formation positions of the substantially arc-shaped protrusions 6, 7 and protrusions 8, 9 are symmetrical with respect to the step direction line at the center of the heat transfer tube, heat transfer is the same regardless of whether the airflow flows from the forward or reverse direction. Performance can be maintained, and installation has an excellent effect of erasing errors over time.

[Brief explanation of the drawing]

FIG. 1a is a front view of a finned heat exchanger according to an embodiment of the present invention, FIG. 1 is a cross-sectional view of the same heat exchanger along the Moum line, and FIG. Perspective view, 2nd
Figure c is a diagram of thermal fluid characteristics in the same heat exchanger. 1...Fin, 2...Heat transfer tube, 3...
...Still area, 4...Temperature boundary layer, 5...
...Part of fin collar, 6°7...approximately arc-shaped protrusion, 8,9...protrusion. Figure III

Claims (1)

[Claims] A group of fins arranged in parallel at regular intervals, through which air flows, and a group of heat transfer tubes inserted at right angles to the group of fins, through which fluid flows, are provided, and gaps in the row direction around the group of heat transfer tubes are provided. A heat exchanger with fins, in which a substantially arc-shaped protrusion facing the airflow is provided on the fin surface, and a plurality of protrusions are provided on the fin surface in the gap in the direction of adjacent steps perpendicular to the inflow direction of the airflow. vessel.