RU2415364C1 - Heat transfer method - Google Patents

Abstract

FIELD: power industry.

SUBSTANCE: method of heat transfer mainly through the tube wall of high-stressed heat exchanger, which consists in the fact that according to counterflow diagram the heated liquid is provided with translational movement along the generatrix of the tube, and with rotational movement about the tube with geometric ratio of flow passages for heating and heated liquids; at that, in order to provide additional degree of freedom - rotational movement of heated liquid about the axis of screw channel - the angle of ascent of the latter about the tube is set so that it is smaller that rotation angle of heated liquid about the axis of screw channel owing to making the upper part of section of screw channel above piece of contact of heated liquid of that section with heat exchange tube.

EFFECT: increasing heat removal from heating liquid to heated liquid, improving operating reliability owing to absence of critical areas with high values of thermal cyclic stresses at heat exchange on water-steam boundary line.

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Description

The invention relates to heat exchange technology and is intended for use in a straight-through high-voltage vertical steam generator of a modular type monoblock steam generating nuclear power plant (NPP) operating on a liquid metal coolant in the mode of variable loads.

Known heat exchange element of the type "pipe in pipe", mainly the Field tube, and the inner pipe has a variable thickness, stepwise changing along the medium / Duntsev Yu.A. and others. The heat exchange element of the type "pipe in pipe". SU. A.S. No. 422935. F28D 7/10. Priority - 11/15/71. Publ. Bulletin of inventions No. 13. 04/05/1974 - analogue.

The disadvantage of this technical solution is the low reliability of the heat exchange element due to the design of the inner pipe at relatively low heat removal values, since the welds of the connected sections of this pipe can cause cracks in the regime of variable thermocyclic stresses during operation, as well as the presence of large hydraulic resistances at the movement of fluid in the bore of the inner pipe due to its sharp expansions. This will be facilitated by the vibration of the inner pipe relative to the outer, as the fluid flow moves under high pressure.

Known heat exchange pipe with annular grooves on the outer surface and their corresponding protrusions on the inner surface, having cylindrical end sections, and between the grooves are made arcuate annular hollows in the form of a globoid, the smallest diameter of which is equal to the outer diameter of the end sections of the pipe / Dreitzer G.A. et al. Heat exchange pipe. SU. A.S. No. 1374029. F28F 1/42. Priority - 07/03/86. Publ. Bulletin of inventions No. 6. 02/15/1988 - prototype.

The disadvantage of this technical solution is the complex technology of manufacturing the profile of the outer surface and, moreover, the reciprocal inner surface of the pipe of small diameter. In addition, globoid depressions during operation in conditions of even large temperature differences, and this takes place in all heat transfer methods, are stress concentrators, which leads to the appearance of intergranular cracks and subsequent fracture. A pipe with such a profile leads to a deterioration in the heat exchange process between heating and heated fluids due to the appearance of a “heat jacket” due to globoid depressions, which increases the thickness of the “wall” of the pipe when heat-exchanging fluids move, as a rule, but not only in a counterflow pattern . All the disadvantages significantly affect the decrease in the resource of reliable operation of the device design as a whole.

The technical result of the invention is the achievement of a high degree of heat transfer efficiency due to the layout of the elements of the heat exchange surface and the organization of the movement of heat exchanging fluids, increasing the resource of reliable operation of the device design at high specific heat voltages of the occupied volume.

The specified technical result is achieved by the fact that the method of heat transfer, mainly through the pipe wall of a high-voltage heat exchanger, which consists in the fact that the countercurrent flow of the heated fluid gives translational motion along the generatrix of the pipe, and rotational movement around the pipe, with the geometric ratio of the flow cross sections for heating and heated liquids, and to provide an additional degree of freedom - the rotational movement of the heated fluid around the axis of the helical channel - the angle under The removal of the latter around the pipe is set less than the angle of rotation of the heated fluid around the axis of the screw channel due to the implementation of the upper part of the cross section of the screw channel above the contact segment of the heated fluid of this section with the heat exchange pipe.

The essence of the invention is illustrated by drawings, where:

figure 1 is a longitudinal section of a bundle of pipes with channels in the nozzle;

figure 2 is a view a of figure 1 with the outlet channel of the heated fluid.

The heat transfer method is intended for use in a steam generator (not shown) containing a bunch of heat exchange tubes 0, spaced by means of a nozzle in the form of a system of installed disks 1 with holes for heat exchanger tubes 0 and the formation of mixing chambers 2 between disks 1, and on the inner surface of the holes in disks 1 made screw channels 3 of the proposed profile.

The method of heat transfer is as follows.

The liquid metal coolant enters the cavity of the heat exchange tubes 0, the entire length of which is provided by forced heat removal by the heated medium entering the annulus in accordance with the operating mode of the steam generator. The method of heat transfer, which consists in the fact that according to the counter-current scheme of heat-exchanging liquids of the heated fluid, translational motion is imparted in the screw channel 3 along the generatrix of the pipe 0, and rotational - around the pipe 0, with the geometric ratio of the flow cross-sections for the heating and heated liquids, and when moving of the heated liquid in contact with the wall of the heat exchange pipe 0, the wall volume, partially turning into steam, will occupy the upper part of the screw channel 3, thereby organizing additional degree of freedom of movement of the heated fluid / rotation / in the screw channel 3 and, as a consequence, the intensification of heat transfer and increase the characteristics of the heated fluid in terms of heat content. To ensure this degree of freedom, the angle of elevation of the screw channel 3 around the pipe 0 is set smaller than the angle of rotation of the heated fluid around the axis of the screw channel 3 by performing the upper part of the screw channel above the contact segment of the heated fluid of this section with the heat exchange pipe 0.

The application of the proposed method of heat transfer increases the heat removal from the heating to the heated fluid by increasing the area of contact due to the additional degree of freedom of movement of the heated fluid and makes it possible to use for forced heat transfer in a modular steam generator with the most compact tube bundle for a steam generating ship nuclear power plant with an integrated layout operating on a liquid metal coolant in the mode of variable loads that meet the requirements of manufacturability, mont Ms, reliability at high specific heat-occupied volume.

Claims (1)

The method of heat transfer mainly through the pipe wall of a high-voltage heat exchanger, which consists in the fact that the countercurrent flow of the heated fluid gives translational motion along the generatrix of the pipe, and rotational motion around the pipe, with the geometric ratio of the flow cross sections for heating and heated fluids, characterized in that for providing an additional degree of freedom - the rotational movement of the heated fluid around the axis of the helical channel - the angle of the latter around the pipe was set they are smaller than the angle of rotation of the heated fluid around the axis of the screw channel due to the implementation of the upper part of the cross section of the screw channel above the contact segment of the heated fluid of this section with the heat exchange pipe.

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