JPS616590A - Finned heat exchanger - Google Patents

Abstract

PURPOSE:To enhance the heat transfer performance of a plate fin by reducing the dead water region developed in the wakes of heat transfer pipes by a structure wherein cut-and-rised parts, the leg portion and the triangular opening of which are lain along a curve smoothly deflecting the stream line of air flow, are provided on the plate fin so as to face the openings opposite to the stream line of air flow. CONSTITUTION:A plurality of cut-and-rised parts 10, the two sides parallel to the front edge of a fin (the upper stream end of a fin with respect to the air flow) of each of which are open in triangular forms, are provided in a domain lying between the line connecting the centers of heat transfer pipes on the upstream side of the air flow flowing in the direction indicated with the arrow 8 or in the first row and the front edge of the fin. In addition, as for the triangular form of the opening, the angle between the flat fin and the hypotenuse, which lies nearer the heat transfer pipe than the leg, is made an angle of 45 deg. or less. Further, groups of upright shaved parts 9, which lie in rows of the groups of the upright shaved parts 10, are arranged around the heat transfer pipe. The arrangement of a plurality of the cut-and-rised parts 9 and 10 on the flat fin 5 is equal to the state that a plurality of short fins stood in the direction of air flow on the flat fin 5. A thin temperature boundary layer is formed on each of said short fins, the air side heat transfer rate is remarkably improved due to the so-called leading edge effect.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention 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. 4, the conventional heat exchanger consists of a group of flat plate fins 1 arranged in parallel at regular intervals and a group of heat exchanger tubes inserted at right angles to the group of fins 1. 2, gas flows between the fins in the direction of the arrow 3 and exchanges heat with the fluid inside the tube.

In this structure, there is a dead area 4 at the downstream part of the heat transfer tube as shown in Figure 6.
occurs, and the amount of heat exchange between the fins and the gas in this area is small, which is an obstacle to improving the heat transfer performance of the heat exchanger.

Purpose of the Invention The present invention eliminates the above-mentioned drawbacks of the conventional technology, and improves the heat transfer performance of the fins by reducing the dead area that occurs at the trailing end of the heat exchanger tube. The purpose is to improve performance.

Structure of the Invention The finned heat exchanger of the present invention is composed of flat plate fins arranged in parallel at regular intervals and through which air flows, and heat transfer tubes inserted at right angles to the flat plate fins and through which fluid flows. and the flat plate fin is provided with a cut-and-raised part having legs along a curve that smoothly deflects the streamline of the airflow and a triangular opening so that the opening faces the streamline of the airflow. be. ′! In addition, the height of the above-mentioned cut-and-raised portion is gradually increased from the upstream side of the airflow around the heat exchanger tube.

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. 1 is a plan view of the fins in the heat exchanger, and FIG. 2 is a sectional view taken along line AA' in FIG. Moreover, FIG. 3 is a side view from the direction of air flow (arrow 8).

Between the upstream side of the airflow flowing in the direction of arrow 8, that is, the line connecting the centers of the first row of heat transfer tubes, and the fin front edge (the fin upstream end with respect to the airflow), there are two side parts parallel to the fin front edge. A plurality of triangular openings 1o are arranged. The triangular shape of the opening is such that the angle between the oblique side closer to the heat transfer tube and the flat plate fin is 46° or less. Further, a cut and raised group 9 connected to the above-mentioned cut and raised group 1-'O is arranged around the heat exchanger tube. This cut-up 9 is
It has a triangular opening facing the streamline of the airflow, and legs 11 arranged concentrically with the center of the heat exchanger tube or with an appropriate curvature, and the height of the cut-up is set from the upstream side of the airflow around the heat exchanger tube. The height of the cut-and-raised portion 10 is successively increased on the downstream side.

Next, around the second row of heat transfer tubes from the leading edge of the fins (airflow upstream end of the fins), a plurality of l-shaped raised tubes 9 and 10 similar to those of the first row of heat transfer tubes are arranged.

Since the flat fin 6 is provided with a plurality of cut and raised fins 9 and 10, the flat fin 6 has a plurality of short fins lined up in the airflow direction, and a thin temperature boundary layer is formed on each of these short fins. The so-called leading edge effect significantly improves the air-side heat transfer coefficient. In addition, the leg part 1 of the cut and raised part 9
1 has an appropriate angle and curvature to deflect the streamlines of the airflow, so it smoothly guides the streamlines of the airflow to the wake of the heat exchanger tubes 7, and eliminates the dead zone 4 of the conventional flat plate fin 1 downstream of the heat exchanger tubes. Significantly reduces and increases the effective heat transfer area. Furthermore, since the airflow is smoothly deflected, pressure loss due to the shape of the heat transfer tube is extremely small. Furthermore, as mentioned above, the height of the raised notches 9 and 10 having triangular openings is made gradually larger from the upstream side, and the raised notches 0 are arranged concentrically from the center of the heat exchanger tube, so that the airflow is It turns toward the center of the heat exchanger tube on the cut and raised oblique side portion 12, further increasing the dead area reduction effect described above.

Effects of the Invention As described above, according to the present invention, it is possible to significantly reduce the dead area generated in the downstream portion of the heat exchanger tube, and as a result, the air side heat transfer coefficient is significantly improved, and the heat exchanger can be made smaller and more compact. Performance can be improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of a fin in a heat exchanger according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A' in FIG. 1, and FIG. side view, 4th
The figure is a perspective view of a conventional heat exchanger, and FIG.
FIG. 3 is a plan view of the fin in the figure. 5...Flat fin, 7. Heat exchanger tube, 8... Airflow inflow direction, 9, 10... Cut and raise, 11
- Cut-and-raise leg part, 12... Hypotenuse part of cut-and-raise. Name of agent: Patent attorney Toshio Nakao Haga 1 person No. 4
Figure 5

Claims (2)

[Claims] (1) Consisting of flat plate fins arranged in parallel at regular intervals, through which airflow flows, and heat transfer tubes inserted at right angles to the flat plate fins, through which fluid flows, the streamlines of the airflow are directed to the flat plate fins. A heat exchanger with fins, which includes legs along a curve to be deflected and a cut-and-raised part having a triangular opening so that the opening faces a streamline of the airflow. (2) The heat exchanger with fins according to claim 1, wherein the height of the cut and raised portions arranged on the flat fins is gradually increased from the upstream side of the airflow around the heat transfer tubes.