JPH018867Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a heat exchanger with fins used as a cross-fin coil. The present invention relates to a heat exchanger with fins in combination with the above.

(Prior Art) In order to improve the performance of heat exchangers with fins, the present inventors first proposed an improved plate-like fin as shown in FIG. 7 (Japanese Patent Application No. 58-23284) ,
(Refer to Japanese Unexamined Patent Publication No. 147995/1983) and a proposal for improving the reticulated fins as shown in Fig.
-94581, Utility Model Application Publication No. 60-2186).

In the former method, as shown in FIG. 7, a large number of louver-shaped cut and raised pieces 15 are formed on the plate-like fin 11, a large number of openings 16 are formed on the plate-like fin 11, and these are fitted into the heat exchanger tubes 12. With respect to the air flow direction X,
Its front end 13 and its front end 13 and its rear end 14 and its rear end 1
4 are closed, and although the heat exchange efficiency of this heat exchanger is certainly improved, it is difficult to form narrow louvers or slits in the plate-like fins 11 in processing, and the plate-like fins 11 It was necessary to perform the troublesome work of alternately closing the front ends 13 and 13 and the rear ends 14 of the holder.

In the latter case, as shown in FIGS. 8a and 8b, a large number of net-like fins 21 . , 21a and the rear ends 21b, 21b are alternately closed to form a meandering shape. In this case, the fins are net-like, and the front end 21a and the rear end 21b of the fin 21 are closed.
Since the air is closed, there is no bypass flow that passes between the fins 21 and the air always passes through the thin wire gaps 23. Although the heat exchange between the air and the mesh fins 21 is good, Heat exchange with the fluid flowing through the heat tube 22 has the drawback that the contact area between the reticulated fins 21 and the heat transfer tube 22 is small, and the wire diameter is generally small, so that it is not necessarily good.

(Problems to be Solved by the Invention) Therefore, in view of the above-mentioned conventional defects, the present invention aims to improve the turbulent flow effect of the plate-shaped fins without performing the troublesome process of forming louver-like cut and raised pieces on the plate-shaped fins. The plate-like fins and the reticulated fins compensate for the disadvantages of poor heat exchange efficiency due to the large amount of bypass flow, and also compensate for the disadvantages of poor heat transfer between the reticulated fins and the fluid in the heat transfer tube. It is an object of the present invention to provide a heat exchanger with fins that combines plate-like fins and mesh-like fins in order to improve heat exchange efficiency by taking advantage of their respective advantages.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention has a structure in which the heat exchanger with fins of the present invention is formed by fitting a large number of plate-like fins into a large number of heat transfer tubes. In the heat exchanger with fins, the reticulated fins are formed in a serpentine shape by alternately closing the tip and rear ends of the reticulated fins adjacent to each other in the air flow direction, and are sandwiched between the plate-like fins. In addition, at least the tip of the net-like fin is joined to the tip of a plate-like fin, and the contact angle of water droplets to the net-like fin is 60. It has been subjected to a surface treatment that makes it hydrophilic to less than 100 degrees or water repellent to more than 100 degrees.

(Function) As described above, the present invention closes the tips and rear ends of the net-like fins that are adjacent to each other in the air flow direction, and connects the tips of the net-like fins to the tips of the plate-like fins. By joining with the fins, there is no bypass flow in which circulating air passes between the fins without heat exchange, and the small contact area between the reticulated fins and the heat transfer tube is also improved, improving heat transfer between the reticulated fins and the air. In addition, the net-like fins suppress the development of a temperature boundary layer on the surface of the plate-like fins, which is a drawback of plate-like fins, by suppressing the turbulent flow effect of the air passing through the reticulated fins, allowing heat exchange. This improves efficiency.

(Example) Examples of the present invention will be described below based on the accompanying drawings.

Fig. 1 shows one embodiment of the heat exchanger with fins of the present invention, in which a shows a top view, b shows a front view, and c shows a perspective view, and Fig. 2 shows another embodiment, and a shows a top view. , b shows a front view, and c shows a perspective view, respectively.

In Figures 1 and 2, 1 is a heat exchanger tube, 2
3 is a plate-like fin, and 3 is a mesh-like fin, which is made of wire mesh knitted with thin wires, expanded metal, punching blade, or the like. The reticulated fin 3
With respect to the air circulation direction A hole is made for passing through the heat tube 1, and at least two mesh fins 3, 3 are inserted between the plate-like fins 2, 2, and the tips of the mesh fins 3, 3 are inserted. 3a,
3a is joined to the tip end 2a of the plate-like fin 2 in both the example in FIG. 1 and the example in FIG. It is joined to the rear end portion 2b of the fin 2, but is not joined in the example shown in FIG. Note that the net-like fin 3 may be a single piece, and may be bent at the front end 3a and rear end 3b.

The net-like fins 3 and the heat exchanger tubes 1, the tips 3a of the net-like fins 3, and the tips 2a of the plate-like fins 2 are joined by brazing or the like. The joint with
For example, as shown in FIG. 3b, the reticulated fins 3
Form an insertion notch 3d (shape is half of a tube),
The heat exchanger tube 1 may be sandwiched between the two mesh fins 3, 3 and the joint portion may be brazed, and as shown in FIG.
It is desirable to enlarge the contact area between the fins and the tube by inserting the fins into the tube. Further, the heat exchanger tube 1 may be not only a circular tube but also an elliptical tube or a flat tube.

Further, both surfaces of the reticulated fins 3 are subjected to a hydrophilic or water-repellent surface treatment to prevent water droplets from remaining when the heat exchanger is used as an evaporator. That is, as shown in Figure 4a, the contact angle of water droplets is 40 degrees or less by applying a hydrophilic coating agent, such as a surfactant such as colloidal silica, polyoxyethylene glycol, or phenol ether, or as shown in Figure 4b. A water-repellent coating agent with a contact angle of 100 degrees or more, such as polytetrafluoroethylene, polydimethylsiloxane, or polypropylene, is applied and dried. When such a surface treatment is applied, even if moisture condenses on the fin surface, if the hydrophilic treatment is applied at a temperature of 40 degrees or less, the condensed water becomes a film and falls through the thin wire, and is repelled at a temperature of 100 degrees or higher. In the case of aqueous treatment, the condensed water falls in the form of droplets from the thin wire, the water droplets do not stay on the thin wire, and in any case do not block air circulation, so the heat transfer coefficient is improved.

(Effects) The present invention is as described above, and in particular, the front end portions 3a and rear end portions 3b of the mesh fins 3 adjacent to each other in the air flow direction X are alternately closed to form a meandering shape. , sandwiched between the plate-like fins 2, 2..., and at least the tip portions 3a... of the mesh-like fins 3...
By joining the tip portions 2a of the plate-like fins 2, the following effects are achieved.

(1) By alternately closing the tips 3a and rear ends 3b of the adjacent reticulated fins 3, there is no bypass flow of air passing between the fins without heat exchange, and the air is always connected to the reticulated fins 3. The heat exchange efficiency is improved.

(2) Moreover, the tip portion 3a of the reticulated fin 3...
By joining the tip portions 2a of the plate-like fins 2, it is possible to prevent the fin efficiency from decreasing when only the mesh-like fins 3 are used.

That is, as shown in FIG. 5, in the case of only the mesh fins 3 as shown in _FIG . Since the temperature difference △T with the air temperature T _p is small, it does not contribute much to the heat exchange efficiency, but as shown in Figure b, in the case of the present invention, the temperature T _a at the tip of the net-like fin is equal to that of the plate-like fin 2. The temperature of heat transfer tube 1 increases due to heat conduction from the tip.
Since it is close to T _p , the temperature difference △T from the air temperature T _p is large, so the tip of the reticulated fin 3 is
It was found that the tip of the
It can be seen that the joints with the plate-like fins compensate for the drawbacks of the net-like fins.

(3) In addition, as shown in Fig. 6, in the case of only the plate-like fin 2 as shown in Fig. 6 a, there is a temperature boundary layer Y on the surface.
occurs, which becomes thermal resistance and impedes the heat transfer coefficient. However, when the mesh fins 3 and the plate-like fins 2 are combined as shown in FIG. This inhibits the development of the temperature boundary layer, and by making the layer thinner, the defects of the plate-like fins 2 are compensated for and the heat transfer coefficient is improved.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the finned heat exchanger of the present invention, in which a is a top view, b is a front view, and c is a perspective view.
FIG. 2 shows another embodiment of the present invention, in which a is a top view, b is a front view, and c is a perspective view. Figures 3a and 3b show other practical aspects of the reticulated fin. Figure 4a shows hydrophilic,
FIG. 4b is a diagram showing the shape of water-repellent water droplets, FIG. 5a is a diagram showing the temperature situation of only the net-like fins, and FIG. 5b is a diagram showing the temperature situation of the combination of the net-like fins and the plate-like fins. FIG. 6a is a diagram showing the occurrence of a temperature boundary layer Y in a combination of a plate-like fin and a combination of a mesh-like fin and a plate-like fin. Figure 7 is a longitudinal cross-sectional view of a conventional heat exchanger with fins having flat louver fins, and Figure 8a.
1 is a top view of the previously proposed heat exchanger with mesh fins, and FIG. 1B is a side view of FIG. DESCRIPTION OF SYMBOLS 1... Heat exchanger tube, 2... Plate-shaped fin, 2a... Tip part of plate-shaped fin, 3... Reticular fin, 3a...
Tip of the net-like fin, 3b... Rear end of the net-like fin, X... Air flow direction.

Claims (1)

[Claims for Utility Model Registration] (1) In a heat exchanger with fins formed by inserting a large number of plate-like fins 2, 2... into a large number of heat transfer tubes 1, 1..., the reticular fins 3, 3... The front end portions 3a, 3a and the rear end portions 3b, 3b of the reticulated fins 3, 3 adjacent to each other in the air circulation direction A fin-attached heating device characterized in that the tip portions 3a, 3a... of the reticulated fins 3, 3... are joined to the tip portions 2a, 2a... of the plate-like fins 2, 2... exchanger. (2) At least the reticulated fins 3, 3... are subjected to a surface treatment to make the contact angle of water droplets hydrophilic at 40 degrees or less or water repellent at 100 degrees or more. Heat exchanger with fins.