JPH0517366U - Heat exchanger plate fins - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a plate fin for a heat exchanger that eliminates the stagnant region of the air flow in a corrugated plate fin used at low wind speed, is hard to frost, and does not increase the flow resistance. . [Structure] A thin metal plate is bent to form a trapezoidal wave-shaped cross section in the air flow direction. A large number of dimples for forming a turbulent flow are provided so as to project only on the concave side of the top and the valley.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a plate fin used in a relatively low wind speed range, such as a heat transfer fin of an air conditioner heat exchanger.

[0002]

[Prior Art]

 In a heat exchanger such as an air conditioner, a gas-liquid two-phase state or a vaporized refrigerant flows through the tube, and air is blown to the outer surface of the tube and the fins contacting the outer surface of the tube. Even if it is an outdoor unit, the wind velocity flowing between each fin is 1.5m or less. In order to improve the heat transfer coefficient of such fins, there has been one in which the plate fins 7 are bent in a triangular wave shape as shown in FIG. 3 and an air flow is circulated in the traveling direction of the waves.

[0003]

[Problems to be solved by the device]

 When a large number of such triangular wave plate fins are formed with a small gap, according to the experiment by the present applicant, an air stagnation region occurs on the lower surface side of the triangular wave top and the upper surface side of the valley, The heat exchange performance of that part deteriorated, and there was a drawback that frost was easily formed there.

[0004]

[Means for Solving the Problems]

 Then, this invention aims at providing the plate fin which has a good heat transfer performance and is hard to produce the stagnant region of an air flow, and takes the following structures in order to achieve the objective. In the plate fin of the present invention, a thin metal plate is bent to form a trapezoidal cross section in the air flow direction. A tube insertion hole is formed in at least one of the top portion and the valley portion, and a large number of turbulent flow forming dimples are provided only on the concave surface side of the top portion and the valley portion.

[0005]

[Action]

 In the plate fin of the present invention, the crests and troughs of the wave are formed flat, so that the occurrence of air stagnation is minimized at that part, and the dimples on the concave side of the plate fin cause the wave to swell. Turbulence can be formed at the top and valley of the to improve the heat transfer performance of that portion. And frost formation of that part is prevented.

[0006]

【Example】

 Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a main part of a heat exchanger having plate fins according to the present invention, and FIG. 2 is a schematic perspective view of the plate fin. The plate fin is made of a metal having good heat conductivity such as aluminum or copper, and is a strip material having a thickness of 0.01 to 0.2 mm continuously pressed by a die. Then, it is bent so that the ridgeline of the wave is located in the width direction of the strip. This trapezoidal wave has a long slope, a short apex, and a trapezoidal opening angle of 120 ° or more and a wide angle, and a tube insertion hole 3 is formed in each apex. The tube insertion hole 3 is barred. In this embodiment, the tube insertion hole 3 is arranged only at the top of the wave, but it may be arranged only at the valley or at both. Next, a large number of dimples 4 for forming turbulent flow are integrally provided so as to project to the concave side of the bent surface at the top and the valley.

The plate fins thus formed are arranged side by side as shown in FIG. 1 with a small gap, and the circular tubes 5 are inserted into the tube insertion holes 3. Then, the inner surface of the tube 5 is expanded, and the outer periphery of the tube 5 and the tube insertion hole 3 are in close contact with each other. The ends of the respective tubes 5 are connected by U-bend pipes (not shown), and the connecting parts are fixed by soldering. The tubes 5 are arranged in a meandering shape as a whole. A refrigerant in a gas-liquid two-phase state or a vaporized refrigerant flows inside the tube 5. Then, air is blown by a fan (not shown), and the airflow 6 flows in the width direction of the fins, that is, the traveling direction of the waves of the fins as shown in FIG. The airflow 6 is guided between the fins in a trapezoidal wave shape. Then, when the direction of the airflow 6 changes along the wave, the airflow 6 is agitated by the dimples 4 at a portion where air stagnation is likely to occur. Generally, frost is apt to occur in the direction change portion of the air flow, but in the present invention, since the dimples 4 are present there, frost formation is restricted by the effect of turbulence.

[0008]

[Effect of the device]

 Since the plate fin of the heat exchanger of the present invention has a trapezoidal wave-shaped cross section in the air flow direction, the plate fins of the stagnation area of the air, which is a heat exchange medium flowing along the waveform, are compared to the conventional triangular waveform. The occurrence is greatly suppressed. Moreover, since a large number of dimples for turbulent flow formation are provided on the concave side of the crests and troughs of the wave, turbulent flow is formed at the crests and troughs where air flow is likely to be stagnant, and heat transfer at those parts. Can be improved. Further, since the dimples are not provided on the convex side of the top and the valley, the flow resistance does not increase, and there is an effect that the heat transfer performance is not deteriorated due to the flow resistance.

[Brief description of drawings]

FIG. 1 is an explanatory view of a main part of a heat exchanger having plate fins of the present invention.

FIG. 2 is a perspective view of an essential part of the plate fin of the present invention.

FIG. 3 is an explanatory view of a conventional heat exchanger.

[Explanation of symbols]

 1 Top 2 Valley 3 Tube insertion hole 4 Dimple 5 Tube 6 Airflow 7 Plate fin

Claims (1)

[Scope of utility model registration request] 1. A thin metal plate is bent to form a trapezoidal wave-shaped cross section in the direction of air flow, and a tube insertion hole (3) is formed in at least one of the top (1) and the valley (2) of the trapezoid. A plate fin of a heat exchanger, characterized in that a large number of dimples (4) for forming a turbulent flow are provided so as to project only on the concave side of the top portion (1) and the valley portion (2).