RU202931U1 - IMPROVED HEAT EXCHANGER - Google Patents

Abstract

The utility model relates to heat exchangers and is intended for use in various types of power plants for removing heat from a heat carrier. The prior art knows various variants of heat exchangers for removing heat from power plants (for example, for cooling water in power plants, where it is a heat carrier). This heat can be the result of both the heating of a heat engine (diesel engine) and the operation of a steam boiler in steam and nuclear power plants. In all these cases, there is a closed loop for the circulation of the coolant medium, and at the end of the thermal cycle, the waste steam, water or any other coolant passes through a heat exchanger, where it is cooled by water from the external environment (this can be a reservoir of a nuclear power plant, as well as sea water on ships) ... Heat exchange can also be carried out for other purposes, for example, in refrigeration plants and refrigerators. The main thing in the process of heat removal is the presence of cooled and cooling media, which interact with each other in the volume of the heat exchanger through its walls. Most known heat exchangers use an array of tubes with a cooling medium passing through the volume of the heat exchanger. In this case, the heat exchange area is determined by the number of tubes, and their number can be quite significant, ideally with full filling of the entire volume of the heat exchanger. This leads to a complication of the design, the appearance of a large number of welded joints of a complex configuration, which not only leads to an increase in the price, but also reduces the reliability during long-term operation. with common adjacent walls, and not only between pairs of spirals, but also between layers of spirals. The result of using the proposed solution is to increase the efficiency of heat transfer.

Description

Technical field to which the utility model belongs

The utility model relates to heat exchangers and can be used in all sorts of power plants to remove heat from the coolant.

State of the art

Known tubular-strip heat exchanger and corrugated tape for a tubular-strip heat exchanger [RF patent for useful model No. 143021], containing at least two tanks connecting the tanks, essentially parallel tubes for the passage of liquid between the tanks, located at a distance between themselves and each having a non-circular cross-section with two opposite, essentially flat and parallel walls, and located between the tubes, corrugated strips of heat-conducting material connected to them, forming channels for the passage of air and each having essentially flat corrugation tops, which connected to the flat walls of the tubes, and essentially flat sections between the tops of the corrugations, and on these flat sections of the tapes there are cuts having bent edges forming louvers for the passage of air from one side of the tape to its other side, the blinds are combined into alternating located on distances between themselves across the bands of the group, in which the the grooves of the cuts are bent in different directions, and between the alternating groups of blinds there are alternating flat areas, which are mutually displaced in opposite directions in the direction perpendicular to the flat areas of the tapes.

The disadvantage of this solution can be attributed to a complex structure of tubes and corrugated tapes with a large number of welded points, which leads to a decrease in the reliability of operation in general, in addition, two external tanks, which increases the dimensions of such a solution.

Also known is a plate heat exchanger [RF patent for invention No. 2351863], containing a plate heat exchanger, including several assembled into a block together with sealing gaskets by means of tightening elements through pressure plates with heat exchange plate fittings containing the main heat exchange part located between two distribution and manifold parts, and holes located in the corner parts of the distribution and manifold parts to ensure the inflow and outflow of cooled or heated liquid or steam, corrugation for the arrangement of sealing gaskets, corrugation of the heat exchange part, corrugation of the distribution and manifold parts, corrugation near the openings. The corrugations of the distribution parts of the heat exchange plates, assembled with their holes coaxially with the fittings of at least one pressure plate, are made in such a way as to provide in the space between adjacent heat exchange plates different hydrodynamic resistance in the area of the distribution and collector parts with an increased value in the area the shortest path from the inlet to the main heat-exchange part and its reduced value in the region of the greatest path from the inlet to the main heat-exchange part with equalization of the hydrodynamic parameters of elementary volumes of cooled or heated liquid when they approach from the inlet through the distribution-collector part to the main heat exchange part.

The disadvantages of this solution include the presence of a complex shape of corrugations that are not completely washed by the flow of liquid or vapor - which reduces the efficiency of heat exchange, and the presence of a large number of heat-removing plates with seals in the structure, which reduces the reliability of the solution as a whole.

This solution is the closest prototype in technical essence to the claimed solution.

Disclosure of a utility model

From the prior art, various kinds of heat exchangers are widely known for transferring thermal energy between two media (heat carriers) [1].

From the prior art, various variants of heat exchangers are known for removing heat from power plants (for example, for cooling water in power plants, where it is a heat carrier). This heat can be the result of both the heating of a heat engine (diesel engine) and the operation of a steam boiler in steam and nuclear power plants. In all these cases, there is a closed loop for the circulation of the coolant medium, and at the end of the thermal cycle, the waste steam, water or any other coolant passes through a heat exchanger, where it is cooled by water from the external environment (this can be a reservoir of a nuclear power plant, as well as sea water on ships) ... Heat exchange can also be carried out for other purposes, for example, in refrigeration plants and refrigerators. The main thing in the process of heat removal is the presence of cooled and cooling media, which interact with each other in the volume of the heat exchanger through its walls. Most known heat exchangers use an array of tubes with a cooling medium passing through the volume of the heat exchanger. In this case, the heat exchange area is determined by the number of tubes, and their number can be quite significant, ideally with full filling of the entire volume of the heat exchanger. This leads to the complication of the structure, the appearance of a large number of welded joints of complex configuration, which not only leads to an increase in the price, but also reduces the reliability during long-term operation.

Water, steam and air are most often used as working fluids - media exchanging heat. Air as a heat carrier is the least efficient due to its low heat capacity even in a significantly compressed state (under pressure) [1]. Water is used as a coolant in modern nuclear power plants, and the so-called "water-water" cycle is used, when the coolant is pressurized water, which excludes its boiling.

In all power plants there is a task of heat removal from the installation - this can be both the task of cooling equipment elements and a diesel engine (or turbine), including due to heating by current in electrical circuits, and ensuring the required water temperature at the entrance to a nuclear reactor at nuclear power plants, which is necessary to control the rate of fission reaction and maintain the specified operating conditions of the installation. There are also auxiliary refrigeration units, which require the release of heat to the external environment. In all these cases, heat exchangers ensure the separation of heat exchanging media, ensuring chemical purity and stability of parameters in the internal circuit.

For these purposes, as a rule, heat exchangers of different designs are used, most often they are a container with an array of small tubes welded into its body through which the external medium is pumped. The number of such tubes can be large, proportional to the amount of heat given off to the external environment; for each tube, the connection to the heat exchanger body is provided by welding, which leads to a large number of welded joints, the quality of which is difficult to control.

The solution chosen as the main prototype uses an array of flat plates with complex corrugation, which are equipped with holes for supplying heat exchanging media (heat carrier and coolant). To seal the contact points, it is proposed to use fittings with a limited service life. The proposed corrugation does not allow the media to wash over the entire surface evenly, which leads to a deterioration in heat transfer to the cooling medium.

In the proposed solution, another way is chosen to increase the heat transfer from the coolant to the cooler, and to increase the efficiency of the volume of the heat exchanger body - which indirectly leads to a decrease in its mass and dimensions, since an increase in heat transfer per unit volume allows to reduce the dimensions while maintaining the heat exchange rate.

For this, it is proposed to use a cylindrical body and channels for the coolant and coolant (interacting media), in the form of spirals. A heat exchanger containing a cylindrical body with channels in its inner cavity made in the form of spirals, the number of turns and the direction of twisting of the spirals coincide, in the center of the cylindrical body there is a through cylindrical cutout. The channels are arranged in layers with a pair of spiral channels in each layer, in pairs the channel spirals are rotated 180 degrees relative to each other in the longitudinal axis, the channels have a rectangular cross-section, the channels in the adjacent turns of the two spirals have a common wall, the channels in the adjacent layers have a common wall, and connection to hot and cold coolant in pairs of spiral channels and between channels in different layers alternates, and the holes for supply and discharge of the coolant of the channels are located at the ends of the cylindrical body.

FIG. 1 shows the appearance of the cavity of one of such spirals. It can be seen that the channel section is rectangular (flattened) and twisted around the longitudinal axis. The area of the long side of the cross-section in the channel will determine the area of interaction between the media, therefore it is necessary to make it as large as possible; but in addition, the height of the channel (the smaller of the sides of the rectangular section of the channel) determines the number of turns in the spiral that can be placed with a given length of the heat exchanger. That is, if possible, it is necessary to increase the number of turns by thinning them. The required ratio must be selected by the developer in each case separately, since there are different media with different viscosities - it is also necessary to ensure a low hydraulic resistance to the flow of the heat exchanging media.

It should be noted that any pipeline or channel for the flow of a liquid or gas will have some resistance to the passage and this is normal, since in any system for the circulation of the medium it is necessary to provide a pressure drop in order for the medium to begin flowing from a zone with a high pressure to a zone with a lower pressure. pressure. Thus, if necessary, pumps are installed to ensure the flow of media through the heat exchanger.

FIG. 2 shows two cavities of channels for exchanging media, from which it can be seen that each spiral is rotated in the longitudinal axis of rotation at an angle of 180 relative to each other: this is necessary for the uniform course of the spirals and the absence of intersection points. At the same time, such a shear angle gives a uniform distance between the channel walls along the length of the spiral, which is important for uniform heat transfer and ensuring the symmetry of the structure as a whole. Shown in FIG. 2 cavities represent their volume in the heat exchanger body, however, the channels themselves are voids in the said spiral heat exchanger body.

FIG. 3 shows a spiral heat exchanger, in which, for the sake of clarity, a cut-out of 1/4 of its part is made. Thus, you can observe its internal structure. One can see the course of the spirals along the height of the heat exchanger, and the helicity of their structure. From the ends of the heat exchanger body you can see the openings for the inlet and outlet of the media, which are made on both sides - that is, the medium is fed into the spiral from one side, on the other side it comes out through a similar opening. The shape of such holes is shown as rectangular, but they can be round or any other convenient for the consumer. External systems can be connected by welding fittings into the heat exchanger, or in another convenient way. The way of external connections can be chosen by the consumer based on the existing level of technology.

The most preferred materials for manufacturing are metals due to their high thermal conductivity in most cases, as well as their high strength and durability. However, the type of body material is not included in the distinctive part of the formula of the proposed solution, and may be different. The body itself can be made by welding the component parts (in the case of metal production) or by gluing together for hybrid materials (for example, cermets and the like).

FIG. 4 shows the appearance of the assembled spiral heat exchanger, with openings at the ends for the inlet and outlet of heat exchanging media, and the cylindrical nature of the body. You can also see a cutout in the center of the heat exchanger body, which makes it possible to reduce its weight, since the manufacture of a spiral with a very small inner diameter is ineffective, since with a decrease in the inner radius, the area of the channels per unit length of radius also decreases, and their production becomes technologically difficult. Shown in FIG. 1, 2, 3 spiral channels ensure the simplicity of the design of the heat exchanger, but their heat exchange efficiency is determined by the contact area of the adjacent sides of the channels, that is, the area of interaction of the interacting media.

The walls of the spirals are made common, thus, the media in them exchange heat between adjacent loops of two spirals, with a change of loops of the "hot" - "cold" type. Making the walls thin between the turns of the two spirals not only minimizes the consumption of materials, but also ensures the exchange of heat between the media in the channels.

The very spiral structure of the channels for heat exchanging media provides a high filling of the volume of the body both by the spiral itself and a large contact area, especially when making the channels for heat exchanging media as thin as possible. In this case, the number of turns of the spirals increases, and the area of their walls among themselves in the same volume of the heat exchanger body. However, for technical reasons, both constructive and related to the properties of liquid media, the number of turns in the spiral is limited for a given length of the body, since the flow of heat transfer fluids through thin channels increases their hydraulic resistance and can be hindered.

FIG. 5 shows a longitudinal section through a heat exchanger body and its internal arrangement, similar to that shown in FIG. 3, where a 1/4 cut was made from the heat exchanger body. This design is a prototype for the proposed solution.

Figure 6 shows the external view of the proposed heat exchanger with a cutout into the cavity of its body. It can be seen from the figure that channels for the coolant are made inside its cavity, through which cold and hot media are pumped. The channels are made spiral, but are arranged in layers extending from the center and covering each other. In this case, an increase in the contact area of the heat carriers exchanging heat is ensured - and this, in turn, increases the heat transfer between the media, since an increase in the interaction area, other things being equal, gives an increase in heat transfer [1]. An increase in the area of the joint walls will occur with an increase in the number of layers in the proposed solution, so that the more layers, the greater the area and efficiency.

FIG. 7 shows a section of the proposed solution along the longitudinal axis of its body. As you can see, the channels have a rectangular cross-section, and the type of the coolant (hot, cold) alternates not only in pairs of turns, but also between the layers of spiral channels. This is achieved by the whole set of distinctive features of the solution: the spiral shape of the channels, the presence of two pairs of channels in each layer, and the channels in the pair are shifted along their axis by 180 degrees between each other, the hot and cold coolant (signs + and - conventionally in Fig. 7) alternate between themselves twice: when feeding into pairs of channels, and when feeding into pairs of channels of different layers. Thus, the full use of the volume of the heat exchanger body is ensured - all channels have a different type of coolant in all channels adjacent to them, which means an increase in the contact area of the media exchanging heat.

The larger the wall area between the channels, the higher the heat transfer between the heat carriers of the hot and cold medium. Thus, not only vertical walls, but also lateral ones participate in the heat exchange in the proposed solution - and an increase in the number of layers gives an improvement in heat exchange.

The claimed solution is simple and industrially applicable, being a symmetrical heat exchanger.

The proposed technical solution is new, and has the following fundamental differences from the prototype:

the channels are arranged in layers with a pair of spiral channels in each layer, in pairs the channel spirals are rotated 180 degrees relative to each other in the longitudinal axis;

channels have a rectangular cross-section, channels in adjacent turns of two spirals have a common wall, channels in adjacent layers have a common wall;

connection to hot and cold coolant in pairs of channels and between channels in different layers alternates;

the openings for supply and discharge of the coolant of the channels are located at the ends of the cylindrical body.

Thus, the entire set of essential features of a utility model was previously unknown and leads to a new technical result - an increase in the efficiency of heat transfer.

Brief Description of Drawings

FIG. 1 shows the shape of the cavity of the spiral channel. FIG. 2 shows the shape of the cavities of two spiral channels with a 180-degree shift between each other. FIG. 3 shows the external view of a spiral heat exchanger with a cutout into the cavity of its body. FIG. 4 shows the appearance of the assembled spiral heat exchanger. FIG. 5 shows a cross-section in the longitudinal plane of a spiral heat exchanger. FIG. 6 shows the external view of the proposed heat exchanger with a cutout into the cavity of its body. FIG. 7 shows a cross-section of the proposed heat exchanger in the longitudinal plane.

List of used literature

1. Stepanov O.A., Zakharenko S.O. The basics of heat transformation. SPb .: Lan, 2019, 128 p.

Claims (1)

A heat exchanger containing a cylindrical body with channels in its inner cavity, made in the form of spirals, the number of turns and the direction of twisting of the spirals coincide, in the center of the cylindrical body there is a through cylindrical cutout, characterized in that the channels are arranged in layers with a pair of spiral channels in each layer, in pairs of spirals of channels are rotated 180 degrees relative to each other in the longitudinal axis, the channels have a rectangular cross-section, channels in adjacent turns of two spirals have a common wall, channels in adjacent layers have a common wall, and the connection to hot and cold coolant in pairs of spiral channels and between channels in different layers alternate, and the holes for supply and discharge of the coolant of the channels are located at the ends of the cylindrical body.

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