JPS5912297A - Heat exchanger - Google Patents

Abstract

PURPOSE:To improve water wettability of fins and enhance heat-exchanging efficiency, by a method wherein an appropriate heating step is provided in the production process, and a plurality of crater parts which can be formed by heating are formed at the surfaces of the fins. CONSTITUTION:The fins are formed by press working, and then the crater parts are formed at the surfaces of the fins by appropriate heating. Alternatively, plate form aluminum fins and a pipe are fixed to each other by enlarging the pipe or other method, and then the crater parts are formed at the surfaces of the fins by providing an appropriate heating step. An Fe component contained in the fin material has an effect on the formation of the crater parts. The component for forming the crater parts at the surfaces of the fins is not limited to the Fe component but may be any one which can form the crater parts at the surfaces of the fins when being heated, and the heating temperature is not limited either.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger, in which a heating step is appropriately provided during the manufacturing process of the heat exchanger, and a large number of craters generated by the heating are formed on the fin surface to prevent water wetting of the fin. It has improved characteristics.

In heat exchangers such as room air conditioners, the water wettability of the fin surface of the evaporator is attracting attention as it is closely related to heat exchange efficiency, and various aluminum surface treatments can be applied to improve the water wettability of heat exchangers. I'm trying.

Recently, efforts have been made to improve the performance of heat exchangers by cutting and raising the fins, and by creating many thin grooves on the inner surface of the pipes. This makes it difficult to cut the fins, and the need for surface treatment of the fins increases.

Types of surface treatment include boehmite treatment, chromate treatment, alumite treatment, resin-based surface treatment, etc., but all of them require a huge investment in equipment, resulting in a significant increase in cost.

Additionally, capital investment is required to prevent pollution from treated wastewater. Recently, pre-coated fin materials made of surface-treated aluminum coils have been commercially available, but the costs increase considerably, so these fin materials can only be applied to a limited number of heat exchangers.

Generally, when a heat exchanger is used in a wet state, such as an evaporator, where water droplets adhere to the fins, the ventilation resistance of the heat exchanger when it is wet increases to approximately twice the ventilation resistance when it is dry, significantly reducing heat exchange efficiency. I'm letting you do it.

The purpose of the present invention is to provide an appropriate heating step during the manufacturing process of a heat exchanger and form a large number of craters on the fin surface due to the heating, thereby improving the water wettability of the fin and improving heat exchange efficiency. It is something.

The present invention provides an appropriate heating step during the conventional manufacturing process of a heat exchanger to form a large number of craters on the fin surface by heating the fin appropriately, thereby increasing the surface roughness of the fin surface. The contact angle of attached water droplets becomes small, resulting in very good water wettability.

The present invention is possible without significantly changing the conventional heat converter manufacturing process.

An embodiment of the present invention will be described below. In general, aluminum fin materials used in heat exchangers are widely used, such as pure 1F, 99.0% or more pure aluminum-based materials such as Al100 and A1200, which have excellent workability, corrosion resistance, and thermal conductivity. Such a fin material is produced by melting, casting, hot rolling, repeating cold rolling several times, cutting the material to a desired width, and then final annealing the fin coil to produce a finished product. The final annealing conditions for the fin coil are generally a heat treatment at a temperature of 300 to 400C for several hours.

Note that intermediate annealing for several hours at a temperature of 300 to 400 t;' may be provided as an intermediate step of cold rolling.

The inventor heated the final annealed aluminum fin material (test fin material Al100) to 610C in the atmosphere and observed the surface of the fin material 1 with a scanning electron microscope, as shown in Figure 2. It was discovered that a large number of craters 3 (bit-shaped dents) each having a size of several microns were formed on the fin surface.

When the components inside the crater portion 3 formed on the fin surface were analyzed, the Fe component was analyzed.

Therefore, an additional step is to heat an aluminum fin material with a higher Pa component content than the fin material Al100 under the same conditions as above.
When a JO experiment was conducted, it was confirmed that more craters were formed on the fin surface than in Figure 2.

This made it clear that the Fe component contained in the fin material influenced the formation of the crater portion. FIG. 1 shows the same sample as the sample in FIG. 2 heated to 400C in the atmosphere, and in this case no crater portion was formed on the fin surface. When the contact angle of water droplets adhering to the fin surface is measured for a fin having a large number of craters 3 on the fin surface as shown in Fig. 2, the contact angle is 20.
It was found that the water wettability was very good.

Therefore, in order to improve the water wettability of the heat exchanger, it is preferable to provide an appropriate heating step during the manufacturing process of the heat exchanger to form a large number of craters on the fin surface caused by the heating.

Specifically, after forming a fin with a press, only this fin may be appropriately heated and a crater portion may be formed on the fin surface by this heating, or the plate-shaped aluminum fin and the pipe may be fixed by expanding the pipe, etc. After the fins are combined into a heat exchanger, a heating step may be performed as appropriate to form crater portions on the fin surfaces.

Furthermore, in the manufacture of so-called corrugated fin heat exchangers in which the fins are continuously bent into a wave shape, vacuum brazing, inert atmosphere brazing, flux brazing, etc. are generally used to securely join the fins and pipes. be done. In this case, the heating at the time of joining the fin and the pipe may also serve to form a crater on the fin surface. Furthermore, even in the case of an aluminum heat exchanger in which fins and pipes are integrally extruded, crater portions can be formed on the surfaces of the fins and pipes by providing an appropriate heating step during the heat exchanger assembly process. Note that Fe is a component that forms craters on the fin surface.
Any component may be used as long as it forms a crater portion on the fin surface by heating, and the heating temperature is not limited either.

According to the present invention, a heating step is appropriately provided during the conventional manufacturing process of a heat exchanger, and a large number of craters are formed on the fin surface by the heating, so that the water wettability of the fin can be significantly improved. performance can be improved.

[Brief explanation of the drawing]

Figure 1 shows 400 fins made of aluminum material Al100.
A photograph of the fin surface when heated to 1:', Figure 2 is 1.
This is a photograph of the fin surface when the fin shown in the figure is heated to 6100°C. 1... Fin material, 2... Flat part, 3... Crater part. Kuni) 2nd prisoner

Claims (1)

[Claims] 1. In a heat exchanger that combines plate-shaped aluminum fins and pipes, a heating step is appropriately provided during the manufacturing process of the heat exchanger, and a large number of craters are formed on the fin surface due to the heating. A heat exchanger characterized by: 2. The heat exchanger according to claim 1, wherein a large number of craters are formed on the surface of the fins by heating when suitably joining the plate-shaped aluminum fins and the pipes.