SU1601495A1 - Heat-exchanger tube - Google Patents

Abstract

The invention relates to heat and refrigeration engineering and can be used in any industry area where the in-line condensation process is used. The purpose of the invention is the intensification of heat transfer in the process of condensation of the coolant in the vertical arrangement of the pipe. The insert 2 installed in the pipe 1 consists of separate sections, in the gaps 3 between which the condensate caps 4 are installed on the inner surface of the pipe 1. The insert 2 can be made hollow and open at the ends, and the lower edge 6 of the condensate cap is placed in the cavity of the insert 2 Insert 2 may be made of a mesh with apertures smaller than the capillary constant. Condensate caps 4 can be made perforated, and the holes in them have flanging inside the cap 4. In the process, there is a redistribution of the film of condensate inside the pipe 1, which leads to improved heat transfer. 4 il.

Description

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The invention relates to heat and chemical engineering and can be implemented in any field of industry where a condensation process is used with inside vertical pipes.

The purpose of the invention is the intensification of heat transfer in the process of condensation of the coolant with a vertical arrangement of the pipe.

FIG. 1 shows a heat exchange tube with a hollow insert, cross section; FIG. 2 — tube with continuous insert, cross section, in FIG. 3 is a section A-A in FIG. in FIG. 4 is a section B-B in FIG. 2. The heat exchange tube 1 contains an insert 2 placed in its cavity with longitudinal ribs contacting with the inner surface of the tube 1, 20 I which is made of a composite of: - separate sections installed along: the length of the tube with gaps 3, which are located condensate caps 4, adjacent the upper edges 5 25 | To the inner surface of the pipe 1 and tapering to the lower edge 6. The insert 2 can be hollow and open from the ends, while the lower edge 6 the cap 4 is placed in the cavity Q of the insert 2. The insert 2 may be flax of mesh with hole sizes, less capillary constant. Condensate caps 4 can be made perforated and ,,: have flanging 7 located on the inner surface of the caps.

Heat exchanger tube is used as follows.

The condensate formed on the surface of the pipe JQ 1 under the action of surface tension forces is drawn into the corners formed by the tops of the ribs of the insert 2 with the surface of the pipe 1, and

flows into the stream under the action of force 5

t tinsel. After passing through the condensate cap 4, the condensate is either

it is dropped into the center of pipe 1 and removed under the influence of gravity, or under the action of surface and Q capillary forces is redistributed along box 2, wetting its surface and forming additional streams in the corners between adjacent ribs. Artificial wetting of the entire surface of a solid insert of oleophilic material with the help of condensate caps 4 allows a greater degree of use of the difference of adhesion forces to displace the condensate from the pipe surface to the surface of the insert. As a result of this redistribution of condensate, a decrease in the film thickness on the surface of the pipe 1 occurs.

The introduction of the lower edge 6 of the cap 4 into the hollow corrugated sheet or mesh insert 2 prevents condensate from returning (pushing away) from the caps 4 to the underlying surface of the pipe 1. The use of the corrugated insert 2 from the mesh with cell sizes smaller than the capillary constant adds to the condensate acting on the film surface forces capillary contraction. In the case of a solid or non-perforated hollow insert, the steam trap caps 4 must be perforated (to allow the steam to pass to the surface of the pipe 1 and reduce the steam velocity in the narrow section of the cap 4. To prevent the flow of the film through the perforation of the caps 4, holes must be made with flanging 7 inside the cap ( for example, by piercing them).

The execution of the insert from separate parts together with the installation of cense-caps between them allows reducing or stopping the growth (along the pipe height) of the curvature radius of the meniscus surface of the stream at the points of contact of the ribs of the insert 2 with the pipe 1. This makes it possible to maintain the prevailing influence of surface forces on the whole the height of the pipe in the case of using long pipes (in the chemical industry, for example, vertical capacitors are used with a length of 6 m and more), for such a composite insert will also be technological e in the manufacture and installation, and in the case of a hollow insert, bent like a leaf spring, the rejection of the paired structure will allow it to be used in pipes made of any materials and to intensify condensation not only in new, but also in equipment already in operation.

Claims (3)

1. A heat exchange tube, in the cavity of which a coaxial insert is placed with one longitudinal ribs in contact with the inner surface of the pipe, characterized in that, in order to intensify heat transfer in the process of condensation of the heat transfer fluid when the pipe is vertically arranged, the insert is made up of individual sections installed along the length of the pipe with gaps in which condensate caps are located adjacent. upper edges towards the inner surface of the pipe and tapering towards the lower edge 2. A pipe according to claim 1, about 1 that is so that the insert is made hollow and open from the ends, and the bottom edge of the condensate drain the cap is placed in the cavity of the insert, 3. A pipe according to claim 1, wherein the insert is made of a grid. i A. The pipe according to claim 1, characterized in that the condensate caps are perforated and have flanges located on the inner surface of the ring. packs. /(-BUT Fig.Z FIG. 2 6-6 FIG. four