RU181849U1 - Air Cooled Heat Exchanger - Google Patents

Abstract

The utility model relates to the field of heat engineering, in particular to air-cooled heat exchangers, and can be used in various industries where there is a need for heat transfer in technological processes. An air-cooled heat exchanger contains a heat-exchange surface made of horizontal finned tubes in a triangular pattern layouts with distances between the centers of three adjacent pipes of adjacent rows with the formation of an equilateral triangle, at least one a fan unit, the impeller of which is kinematically connected with a drive located on the suction line side, and a flow part made of composite material using polyester resins, which includes a confuser, a working case, and an air supply element sequentially passing into each other on the suction line side connecting it with the heat-exchange surface. The cone is made in a longitudinal section curved, its surface is formed by the rotation of a fragment of a flat conical se a straight circular cone around a straight line that is the axis of rotation of the impeller, and the air supply element is made in the form of an air distribution duct. longitudinal stiffeners, the end edges of which are intended for the location of fasteners, are made with bends A useful model allows you to create an air-cooled heat exchanger that meets the current level of apparatus engineering in terms of technical and economic indicators, its manufacturing technology. Structural and technological solutions incorporated in its design contribute to expanding the range of air-cooled heat exchangers to the required dimensions, which are determined by the specific tasks of an enterprise. 5 ill.

Description

The utility model relates to the field of heat engineering, in particular, to heat exchangers and can be used in various industries, namely, where there is a need for heat transfer in technological processes and where heat exchangers can be used for this.

Known heat exchangers for air cooling, consisting of a heat exchange surface, which is a tube bundle of parallel pipes, which ensure its interaction with an external cooling medium, which is used as external air, the supply system of which includes at least one fan installation, mounted on a supporting structure.

The air-cooled heat exchanger is known from the prior art (description of the invention of the USSR No. 378698, class F28B 1/06), comprising a casing with finned tubes fixed inside the tube sheets and a fan for blowing air through the tubes.

The ends of the finned tubes of the air-cooled heat exchanger are smooth-walled and, together with the grilles in which they are fixed, are carried outside the casing, i.e. removed from the zone of air blowing and practically do not participate in the process of active heat removal.

This design of the heat exchanger reduces its operational characteristics in terms of heat transfer efficiency and leads to an increase in its material consumption and dimensions and does not correspond to the modern main direction in the design of air-cooled heat exchangers - the supply of block heat exchangers of maximum factory readiness, the width of which should not go beyond the railway gauge 1- T.

The closest in technical essence and the achieved result to the claimed utility model is a heat exchanger, disclosed in patent RU 2270410, C2, F28D 7/00, 09/10/2004, containing at least one vertical casing open from the bottom and top, made of woven the material is monolithic in cross section in the form of toroidal, cylindrical and ruled surfaces sequentially conjugated to each other in a bottom-up direction, as well as a heat-exchange surface and a fan impeller in each casing. The casing of the heat exchanger is made of fiberglass material impregnated with epoxy resin, and the ratio of the various elements of the casing surfaces to the diameter of the cylindrical surface is selected as follows: h = 1.47 d - 1.49 d; g = 0.58 d - 0.61 d; r = 0.18 d - 0.20d; a = 0.14 d - 0.16 d; b = 0.55 d - 0.57 d where d is the diameter of the cylindrical surface, h is the distance from the beginning of the ruled surface to the mounting base; g is the distance from the beginning of the toroidal surface to the mounting base; r is the radius of the toroidal surface; a is the distance from the beginning of the cylindrical surface to the beginning of the ruled surface, b is the distance from the end of the cylindrical surface to the beginning of the ruled surface. In addition, the heat exchange surface located above the casing is a rectangle in cross section, characterized by the following relationships: n = 1.1 d - 1.2 d; m =, 4 d - 1.42 d, where d is the diameter of the cylindrical surface; n is the smaller side of the rectangle; m is the large side of the rectangle. The heat exchange surface is also made in the form of horizontal rows of pipes arranged in a checkerboard pattern, while the distance between the centers of three adjacent pipes of adjacent rows form an isosceles triangle with a base larger than the sides.

The disadvantages of this design are the following:

A) the use of a low-efficiency open vertical casing open from the bottom and top, made monolithic in cross section in the form of toroidal, cylindrical and ruled surfaces successively conjugated to each other in the upward direction.

Taking into account the terms used in heat transfer technology and fan building, in this case, it is technically correct to call the casing in the following the flow part of the fan installation of the heat exchanger, in which the fan impeller with its drive is installed, made solid in cross section in the form of sequentially conjugated to each other in the direction from the bottom up confuser (previously technically incorrectly designated as a toroidal surface), fan casing (previously designated as cylindrical on top nas) and an air supply device in the form of a diffuser (previously designated as a ruled surface).

The surface of the prototype confuser is formed by rotating an arc of a circle with a radius r = 0.18 d - 0.20 d, where d is the diameter of the fan casing when rotating around an axis coinciding with the axis of rotation of the impeller of the fan unit located in the same plane as an arc, but not passing through the center of its curvature.

Loss of dynamic pressure in the confuser due to its shape, size, workmanship. To ensure a smooth entry of air into the flowing part, confusers with very diverse profiles are used, i.e. surface confusers are made, which are formed by rotation of the curves not in the form of an arc of a circle, but, for example, a fragment of a lemniscate, an ellipse, etc.

There are some smooth curves that provide better aerodynamic characteristics of the confuser than in the prototype: profiling of the confuser is usually done along smooth curves, matching them so that often not only the first, but also the second derivatives are continuous.

The disadvantage of the air supply device in the form of a prototype diffuser connecting the flow part to the heat exchange surface, respectively, having an input cross section in the form of a circle with a diameter d, and the output cross section is an elongated rectangle of the heat transfer surface, characterized by the following relations: n = 1,1 d - 1 , 12d; m = 1.4 d - l, 42d, where d is the diameter of the cylindrical surface; n is the smaller side of the rectangle; m is the large side of the rectangle, there is a large pressure loss due to breaks in the air flow from its walls, due to the large opening angle. At least two walls of the diffuser with a selected ratio of its dimensions have an opening angle α = 38 ° 40 '- 41 ° 44'.

As you know, in pyramidal diffusers there is more pressure loss than in conical ones, and if the opening angle exceeds 40 °, then speed conversion does not occur and losses in such a diffuser exceed losses when the flow suddenly expands. In these cases, it is more advantageous to provide a sudden expansion, (5) i.e. the design of the prototype diffuser does not reduce pressure loss.

B) the implementation of the heat transfer surface of the specified heat exchanger from smooth-walled pipes does not provide sufficient heat transfer: smooth-walled pipes have a relatively low value of the heat transfer coefficient from the air side α _air , while the heat transfer surfaces are designed so that the internal and external heat transfer during heat removal approximately equal.

When forming a heat-exchange surface in the form of horizontal rows of pipes arranged in a checkerboard pattern, at which the distances between the centers of three adjacent pipes of adjacent rows form an isosceles triangle with a base larger than the sides, the so-called a rarefied tube bundle, which, when using smooth-walled tubes, also limits the possibility of high heat transfer efficiency and leads to an increase in the material consumption of the apparatus since to achieve the necessary heat removal compared to finned tubes, the installation of a larger number of smooth-walled pipes is required.

C) the implementation of the elements of the flowing part of the fan unit (previously the “casing”) monolithic in cross section is not technologically advanced due to the complexity of the equipment for their manufacture, difficulties in transportation and installation of them in the apparatus.

All of the above limitations reduce the scope of the known heat exchanger.

Terms with corresponding definitions used in the application for a utility model:

The term "casing (hood)" should be understood as the outer shell of the machine, device, mechanism, apparatus for fastening and maintaining individual structural elements, a protective fence protruding and moving parts, etc. [9]

The term "pipe" should be understood as a product made of steel of a ring-shaped, oval, polygonal or other shape of a hollow cross section of relatively large length. [four]

The term "finned tube" should be understood as a pipe having transverse, longitudinal or spiral ribs on the outer surface [10]. Finning is done in order to increase the heat transfer coefficient.

An integral part of many technological installations and devices in all areas of technology is an axial fan - an aerodynamic blade machine, in which the impeller connected in one way or another to the drive shaft rotates in the fan casing. [2]

The term "fan impeller" should be understood as the rotating part of the fan, in which mechanical energy is transmitted to the air through the dynamic action of its blades. [3]

The term "fan housing" should be understood as the part of the fan in which the impeller rotates. [3]

The term "fan installation" should be understood as a fan together with a complex element located in close proximity to it. Elements located on the suction line are called input elements, and on the discharge line - output elements of fan units. [8]. Such constituent elements of the fan units of heat exchangers at the inlet is a confuser, and at the outlet there are air supply devices (diffusers, air distribution boxes) connecting the fan casing with a blown heat-exchange surface. The air flow in the fan and the elements connected to it are interconnected.

The term "confuser" should be understood as a narrowing channel in which the subsonic velocity of a liquid or gas increases as a result of the conversion of potential energy into kinetic. In fan installations, a confuser is installed in front of the impeller and is often called a collector. [one]

The term "diffuser" should be understood as a profiled channel designed to inhibit the flow of liquid or gas. In the diffuser, the kinetic energy of the flow is converted to pressure. The subsonic diffuser is an expanding channel. The total pressure loss in the diffuser is due to the action of friction forces and increases significantly when a flow stall occurs. [one]

The term "flow part of the fan installation" should be understood to mean a fan casing with an element connected to it from the suction side and from the discharge side of the air-supplying element to the heat exchange surface, which together form a channel through which the transported air passes.

The term "toroidal surface (similar to a torus)" should be understood as the surface formed by the rotation of any curve other than a circle around a straight line that is coplanar with it, but not their axis. [6]

The term "flat conical section" should be understood as the line of intersection of the surface of a straight circular cone with a plane not passing through the top of the cone. [7]

The term "combination" refers to a combination, relative position of something, for example, a combination of fragments of lines.

The term "composite material" should be understood as a material obtained by impregnation with a polymeric binder (mainly polyester resins) of fiberglass of different weaving, various glass mat and roving.

The task to which the claimed technical solution is directed is to expand the arsenal of technical means in this area, as well as to increase the technical and economic indicators of an air-cooled heat exchanger.

The technical result provided by the given set of features is to expand the arsenal of technical means in this area, to obtain an air-cooled heat exchanger that meets the current level of apparatus engineering in terms of heat transfer intensity, reduced energy consumption, and manufacturability of its manufacture.

The technical result is achieved due to the fact that the air-cooled heat exchanger containing a heat-exchange surface formed of horizontal rows of pipes, at least one fan installation, the impeller of which is kinematically connected to the drive located in the flow part from the suction line side, and the flow a part made of a composite material using polyester resins, which includes sequentially passing each other from the side of the suction line of the embarrassment p, the working case and the air supply element connecting it to the heat exchange surface, according to the utility model, the pipes are made finned, and the heat exchange surface formed from horizontal rows of finned pipes is made according to a triangular arrangement with the distances between the centers of three adjacent pipes of adjacent rows with the formation of an equilateral triangle , the confuser is made in a longitudinal section curved, the surface of which is formed by rotation of a fragment of a flat conical section of a straight circular cone, which is the line of intersection of the surface of a straight circular cone with a secant plane that does not pass through its apex, around a coplanar straight line with it, which is the axis of rotation of the impeller, its wall facing the convex side inward of the flowing part, while its geometric dimensions depend on the diameter of the working housing Dpk, having a dimensional ratio Dpk = 0.65 V - 0.9 V, where B is the width of the heat-exchange surface that does not go beyond the railway dimension 1-T, and the diameter of its input section has a dimension ratio Dcf = 1.15 Dpc - 1.45 Dpc, and its height has a size ratio Ncf = 0.1 Dpc - 0.27 Dpc, the height of the working case has a dimension ratio Nrc = 0.15 Dpc - 0.2 Dpc and the air supply element is made in the form of an air distribution box with a height having a dimensional ratio Нвк = 0.2 Dpк - 0.4 Dpк, and which is made in plan in the form of an elongated rectangle, the width of which coincides with the width of the heat exchange surface B, and the length has a dimensional ratio L = 0.95 V-1.4 V, and the flow part is made of unified s conjugated among themselves forming elements in the form of sectors, wherein the standardized shaping elements running portions have longitudinal ribs, the end edges of which, intended for location of fastener elements are formed with outwardly running limb portion.

The essence of the utility model is illustrated by graphic materials, which depict the following:

In FIG. 1 shows a schematic diagram of a heat exchanger;

In FIG. 2 is an enlarged view of a portion of a heat exchange surface;

In FIG. 3 shows a schematic diagram of the flow part of a fan unit;

In FIG. 4 shows the unified forming elements of the flow part;

In FIG. 5 shows a section along aa of FIG. one;

The list of items for the description of the utility model:

1. Heat transfer surface

2. Impeller

3. Impeller drive

4. Confuser

5. Working building

6. Air supply element

7. Unified forming elements

8. Bolted connection

The list of designations for the description of the utility model:

1. Dpк - diameter of the working case

2. NRC - the height of the working building

3. NKF - the height of the confuser

4. Nvk - the height of the air distribution box

5. N - distance from the heat exchange surface to the base

6. h - distance from the inlet section of the confuser to the base

7. Dкф - diameter of the inlet section to the confuser

8. B - width of the heat exchange surface

9. L is the length of the heat exchange surface.

The air-cooled heat exchanger is made of a horizontal type with a lower arrangement of at least one fan installation under the heat-exchange surface (Fig. 1) and contains a heat-exchange surface 1, which is a tube bundle made of horizontal rows of finned tubes in the form of a rectangle, the width of which is determined by the railway gauge 1-T and the design of the heat exchange section, and the length L has a dimension ratio L = 0.95 V-1.4 V.

The use of finned tubes, which, in comparison with smooth-walled tubes, have higher operational characteristics due to an increase in the heat exchange surface, allows one to increase the heat removal from the heat exchange surface.

The triangular (staggered) layout of the heat-exchange surface with the distances between the centers of three adjacent pipes of adjacent rows with the formation of an equilateral triangle (Fig. 2) also contributes to an increase in the hardware heat capacity due to the increase in heat transfer area due to the compactness of the tube bundle, which allows it to volume increase the number of pipes.

The external cooling medium is supplied to the heat exchange surface by a fan unit containing at least an impeller 2 with a drive 3 installed in the duct part of the fan unit made of composite material, which is made in the form of successively passing each other from the suction line of the confuser 4, the working housing 5, and the air supply element 6 (Fig. 1, Fig. 3), the latter provides its connection (not shown) to the heat exchange surface 1 of the apparatus .

The flowing part, the composite material being used as the material for manufacturing, is made of at least four in the form of unified forming elements in the form of sectors (Fig. 3, Fig. 4) that are longitudinally conjugated to each other by known means. stiffening ribs, the end edges of which are intended for the location of fasteners, for example, bolted joints 8 (Fig. 5), are bent outward of the flow part.

Due to such a design of the flow part, the laboriousness of its manufacture is reduced, while the implementation of the manufacture of the flow part elements monolithic in cross section entails the complication of manufacturing and assembly technology in the metal structure (not shown) of the apparatus.

The confuser 4 (Fig. 1) is made in a longitudinal (meridional) section to the point where the curved part of the confuser begins to transition to the working case with a profiled fragment of a flat conical section of a straight circular cone, and this is a particular particular case of the line being formed by the surface of a straight circular cone and cutting plane not passing through its peak, i.e. This circle, ellipse, hyperbola or parabola is determined during the design of the apparatus.

In this case, the diameter of the inlet section of the confuser has a dimension ratio Dкф = 1.15 Dpк - 1.45 Dpк, and its height has a dimension ratio Нкф = 0.1 Dpк - 0.27 Dpк.

This embodiment of the confuser creates the conditions for a smooth inlet of the air flow, reduces the number of vortex formation zones, and provides a selection of confuser design options for the flow part when its compact design is required.

The working body 5 (Fig. 1), the diameter Dp of which has a dimensional ratio of Dpk = 0.65 V-0.9 V, is made with a height having a dimensional ratio of N pk = 0.15 Dpk - 0.2 Dpk.

The air supply element 6 is made in the form of an air distribution box, which, without increasing the energy consumption for the fan, without impairing the supply of air flow to the heat exchange surface 1 of the apparatus, ensures the connection of the flow part (not shown in the drawing) to it and is made with a height having a dimensional ratio Нвк = 0.2 Dpk - 0.4 Dpk, which is made in plan in the form of an elongated rectangle that repeats the dimensions of the heat exchange surface, the width of which is B, and the length L has a dimension ratio L = 0.95 V-1.4 V.

The design of the air supply element 6 in the form of an air distribution box with a height of Нвк = 0.2 Dpк - 0.4 Dpк meets modern trends in the design of heat exchangers and allows, while maintaining the standard distance H from the heat exchange surface to the mounting base, to increase the distance from it to the confuser by h = 0 , 17 Dpк - 0.35 Dpк, i.e. reduce the screen effect of the mounting base on the operation of the fan unit.

The air-cooled heat exchanger operates as follows: as shown in FIG. 1, a fan installation mounted on the metal structure of the apparatus (not shown in the drawing) contains an interconnected impeller 2, a confuser 4, an impeller 5, an air supply element 6. The impeller 2 is driven by a drive 3. Under the action of the impeller blades, the surrounding air (cooling medium) flows around the confuser 4, moves axially and, then passing through the air supply element 6, enters the heat exchange surface and flows around the heat exchange surface formed from horiz ntalnyh rows of finned tubes creates a triangular layout scheme with the distances between the centers of three neighboring tubes of adjacent rows to form an equilateral triangle, extends outwardly, the heat exchange process is performed (cooling of the product flowing through the heat exchange section of the machine, colder coolant).

The results of design and production and technological work indicate that the creation of an air-cooled heat exchanger according to the proposed technical solution will increase the efficiency of its heat exchange, the manufacturability of its manufacture, reduce operating costs and achieve a modern level of apparatus engineering.

Industrial applicability is obvious. Prototypes made by the applicant have proved the feasibility of the task.

The utility model can also be used in the design of heat exchangers for both general and special purposes.

LITERATURE

1. Aviation. Encyclopedia. M. Great Russian Encyclopedia. 1994. p. 220, 287

2. Brusilovsky I.V. Aerodynamics of axial fans. M. "Engineering", 1984. Pp. 3

3. GOST 22270-76 Equipment for air conditioning, ventilation and heating. Terms and Definitions. M. 1988. pp. 6

4. GOST 28548-90. Steel pipes. Terms and Definitions. Table 1, page 1.

5. Kalinushkin M.P. Fan installations. M. High school. 1967 p. 30-31.

6. Levitsky B.C. Engineering drafting and automation of drawings. M. "Higher School" 1998, p. 100.

7. Pugachev P.E. Course of higher mathematics. M. Higher School 1970 p. 104.

8. Recommendations for calculating the hydraulic resistance of complex elements of ventilation systems. M. Stroyizdat. 1981 p. 6.

9. Soviet Encyclopedic Dictionary. M. Soviet Encyclopedia, p. 604

10. STO CCTI 10.002-2007. Elements of pipe heating surfaces, connecting pipes within the boiler and the collector of stationary boilers, section 3.1.36 p. 6.

Claims (1)

An air-cooled heat exchanger comprising a heat-exchange surface formed of horizontal rows of pipes, at least one fan unit, the impeller of which is kinematically connected to a drive located in the flow part from the suction line side, and a flow part made of composite material using polyester resins, which includes consecutively converging into each other from the side of the suction line, a confuser, a working case and an air supply element, it with a heat exchange surface, characterized in that the pipes are finned, and the heat exchange surface formed from horizontal rows of finned pipes is made according to a triangular arrangement with the distances between the centers of three adjacent pipes of adjacent rows with the formation of an equilateral triangle, the confuser is made in a longitudinal section curved whose surface is formed by the rotation of a fragment of a flat conical section of a straight circular cone, which is the intersection line of the surface of a circular cone with a secant plane that does not pass through its apex, around a straight line coplanar with it, which is the axis of rotation of the impeller, its wall facing the convex side inward of the flowing part, and its geometrical dimensions depend on the diameter of the working casing Dр having the dimensional ratio Drk = 0.65 V - 0.9 V, where B is the width of the heat-exchange surface that does not go beyond the railway dimension 1-T, and the diameter of its inlet section has the dimensional ratio Dkf = 1.15 Drk - 1.45 Drk and him in the honeycomb has a dimension ratio of Nkf = 0.1 Drk - 0.27 Drk, the height of the working case has a size ratio of Nrk = 0.15 Drk - 0.2 Drk, and the air supply element is made in the form of an air distribution box with a height having a dimensional ratio of Nvk = 0.2 Drk - 0.4 Drk and which is made in plan in the form of an elongated rectangle, the width of which coincides with the width of the heat exchange surface B, and the length has a dimension ratio L = 0.95 V - 1.4 V, and the flow part is made from unified conjugated forming elements ntov in the form of sectors, wherein the standardized shaping elements running portions have longitudinal ribs, the end edges of which, intended for location of fastener elements are formed with outwardly running limb portion.

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