JPH04122964U - Boiling heat exchanger tube - Google Patents

Abstract

(57) [Summary] [Objective] To provide a heat transfer tube in which bubble generation, that is, boiling heat transfer, is performed smoothly and efficiently. [Structure] Approximately triangular fins 2 are provided on the outer surface of the heat exchanger tube 1.
A large number of cavities 4 having openings 3 between adjacent fin tops are provided independently in the tube axis direction and tube circumferential direction without communicating with each other. [Effect] Since activated steam exists as boiling nuclei 5 in the cavity 4, boiling occurs continuously and efficiently, which further improves heat transfer performance and improves heat exchanger performance. It is possible to achieve smaller size and higher performance.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is designed to be used in heat exchange systems such as the evaporator of turbo chillers and the regenerator of absorption chillers. This invention relates to heat exchanger tubes used in heat exchangers that involve boiling and evaporation of fluids.

0002

[Conventional technology]

Conventionally, in the evaporator of a centrifugal chiller or the regenerator of an absorption chiller, the heat transfer area has been External fin tubes, such as increased low fin tubes, are often used. In order to further promote heat transfer, it always has a boiling nucleus and boils continuously. Such shapes have been studied, and some of them are already in use.

0003 Its shape consists of fins formed by cutting and compression molding with a brush. The heat exchanger tube 1' shown in FIG. By cutting the tip of the fin and tilting it in the direction of the tube axis so that it touches the adjacent fin, There is a heat exchanger tube 1'' shown in FIG. 6 having a tunnel portion 6'' and an opening 3''.

0004

[Problem that the idea aims to solve]

In the boiling heat exchanger tube 1', 1" with the above structure, the liquid that has entered the tunnel section 6', 6" is heated. It is heated and transformed into activated steam, and bubbles appear from the openings 3' and 3'' as shown in Figure 7. Separate as. At this time, not all of the steam inside the tunnel section 6', 6" comes out, but some of it remains and becomes boiling nuclei, which causes continuous boiling heat transfer. Generally, this It is known that the finer and more continuous the bubbles are, the better the heat transfer performance will be. Ru.

[0005] By the way, in the heat exchanger tube 1', 1" as described above, bubbles are not generated in all the openings 3', 3". In some openings 3' and 3'', only liquid is sucked in. In particular, At the bottom of the pipe, steam, which has a lower specific gravity than the liquid, passes through the tunnel parts 6' and 6" and collects at the top. Because it is easy to fill, there are many openings 3', 3" where only liquid is sucked (see Figure 7). ). As described above, boiling was not performed efficiently in conventional heat exchanger tubes.

[0006] The present invention was developed to solve these problems, and its purpose is to eliminate air bubbles. To provide a heat transfer tube in which heat generation, that is, boiling heat transfer, is carried out smoothly and efficiently. There are many things.

[0007]

[Means to solve the problem]

In order to achieve the above purpose, the present invention is characterized by having the following configuration. shall be. In other words, the present invention is suitable for cases where the cross-sectional shape perpendicular to the tube axis is triangular, trapezoidal, etc. When the fins having a section are provided adjacent to each other in the circumferential direction and the axial direction of the tube, In some cases, a cavity with an opening between the tops of adjacent fins is These boiling heat exchanger tubes are installed independently without communicating with the boiling tubes.

[0008]

[Effect]

According to the present invention, each individual cavity formed on the outer surface of the heat transfer tube In the tee, the liquid that flows into this cavity is heated and activated. It becomes steam. A part of this vapor separates and bubbles form in the liquid outside the tube, as shown in Figure 4. and leaves. Inside the cavity where the steam is separated, there is a pipe corresponding to the volume reduction of the steam. Liquid flows in from outside, but activated steam forms boiling nuclei inside the cavity. Because of the remaining steam in the cavity, it quickly develops, resulting in continuous Boiling begins to occur. In addition, since the cavity is independent, steam does not move up the pipe. Since steam boiling nuclei are retained within each cavity, boiling is performed effectively.

[0009]

【Example】

Embodiments of the present invention will be described in detail with reference to the accompanying drawings. Using a heat exchanger tube (copper tube) with a diameter of 19 mm, first, the outside of the fins was applied to the outside using the usual method. Diameter 18.9mm, fin height 0.6mm, fin pitch (axial direction) 26 fins per inch. A finned tube with fins was formed. Next, the tooth tip angle is 100 degrees and the groove depth is 0.6 mm. Compression rolling was performed using a gear tool.

0010 As a result, the compressed fin deforms in the order of (a), (b), and (c) as shown in Figure 2. The fin gradually expands from the tip to the base, contacts the adjacent fins in the front and back, and becomes heavy. The shape of the fins shown in Figure 2(c) is formed, and the final heat exchanger tube 1 has the shape shown in Figure 1. can get. In other words, the outer diameter of the fin is 18.9 mm, the number of ridges in the circumferential direction is 36, and the height of each ridge is 0.6 mm approximately triangular fins 2 are arranged adjacent to each other in the axial direction at a pitch of 26 per inch. The fins 2 form a cluster, and the fins 2 have a cross section in the tube axis direction as shown in an enlarged view in FIG. a cavity 4 having an opening 3 between adjacent fin tops; are installed independently in the axial direction and circumferential direction of the pipe without communicating with each other. It has a structure that allows

[0011] The finned heat exchanger tube 1 having such a structure can be used, for example, as an evaporator of a turbo refrigerator. When used, activated steam is boiling inside the cavity 4, as shown in Figure 4. Since it exists as a boiling kernel 5, boiling occurs continuously and efficiently.

0012

[Effect of the idea]

As mentioned above, according to the present invention, independent cavities each having an opening are provided. The cavities communicate with each other due to the large number of fins formed along the tube axis and circumferential direction between the fins. Compared to conventional heat exchanger tubes, the activation of steam inside the cavity is more This will further improve the heat transfer performance and therefore reduce the size of the heat exchanger. It becomes a heat transfer tube that is extremely advantageous in terms of molding and improving performance.

[Brief explanation of drawings]

FIG. 1 is a partial perspective view of a boiling heat exchanger tube according to the present invention.

FIG. 2 is an enlarged cross-sectional view in the axial direction of the tube for sequentially explaining the means for forming the boiling heat exchanger tube according to the present invention.

FIG. 3 is an enlarged cross-sectional view of the boiling heat exchanger tube in the tube axis direction according to the present invention.

FIG. 4 is a sectional view showing a heat exchange state accompanied by boiling of the boiling heat exchanger tube according to the present invention.

FIG. 5 is a partial perspective view of a conventional heat exchanger tube.

FIG. 6 is a partial perspective view of another example of a conventional heat exchanger tube.

FIG. 7 is a sectional view showing a heat exchange state of a conventional heat exchanger tube.

[Explanation of symbols]

1: Heat exchanger tube 2: Fin
3: Opening 4: Cavity 5: Boiling nucleus

Claims (1)

[Scope of utility model registration request] Claim 1: Fins having tops having a triangular, trapezoidal, etc. cross-sectional shape in a direction perpendicular to the tube axis are provided adjacent to each other in the tube circumferential direction and the tube axis direction, and there is a gap between the tops of the adjacent fins. A boiling heat exchanger tube characterized in that cavities each having an opening are provided independently without communicating with other cavities.