RU2479815C1 - Heat exchanger manufacturing method; heat exchanger from composite materials, and manufacturing method of corrugated plate for heat exchanger - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: in the heat exchanger manufacturing method that involves cutting of corrugated and flat planes made from composite material, prior to assembly of interface points of plates, the tops of corrugations are lubricated with high-temperature glue to stick flat separation plates to corrugated plates, and hardening of high-temperature glue is performed using pressure and heat treatment of the bank at the temperature of 800-1900°C, and then, the bank is sealed with a ceramic component. In the manufacturing method of a corrugated plate for heat exchanger, glue is applied to the surface of the base with a channel prior to the plate moulding, and subsequently, from one end of the base to the other, prepreg is bonded to the surface of the corrugated base; then, the above prepreg is pressed with a corrugated hold-down plate to corrugations of the base and subject to heating for carbonisation of the corrugated prepreg. Heat exchanger from composite materials includes a housing, inside which a bank of separation and corrugated plates is installed, which are rigidly attached to each other and made from identical high-temperature composite material.

EFFECT: increasing the strength of heat exchanger with simultaneous reduction of its weight.

9 cl, 3 dwg

Description

The invention relates to mechanical engineering, namely to the production of corrugated sheets from composite materials and high-temperature heat exchangers used in aviation and rocket and space technology, diesel engines, boilers, etc.

A known method of manufacturing a plate package of a heat exchanger from a composite material, including cutting the size of corrugated and separation flat sheets made of composite material, assembling corrugated and separation flat sheets in a package (see US patent No. 4787443, NKI 165/165, 11.29.1988 g .). In a plate pack of a heat exchanger made of a composite material made in a known manner, corrugated and separation flat sheets are produced by extrusion from a ceramic mass containing mainly silicon carbide, silicon nitride, aluminum nitride, ceramic Si-Al-O-N and silicon. One of the components of the composition is carbon, which interacts in the process of manufacturing the heat exchanger with silicon, forming silicon carbide, a consolidating material of the sheets. The use of extrusion leads to a significant thickness of the sheets, which, in turn, leads, in combination with a relatively low thermal conductivity, to high thermal stresses in a ceramic heat exchanger during its operation.

This method of manufacturing a package of a heat exchanger does not provide the necessary strength of the product and the possibility of reuse at high temperatures.

Closest to the proposed method for the combination of essential features is a method of manufacturing a heat exchanger, comprising cutting the size of corrugated and dividing flat sheets made of composite material, assembling the corrugated and dividing flat sheets in a bag with the cross direction of the corrugations in adjacent layers, subsequent heat treatment and installation in case (see US patent No. 4789585, NKI 428/186, 165 / 134.1, 06/12/1988).

The known method does not allow to produce a heat exchanger with the necessary strength for use at high temperatures and low weight.

Known plate heat exchanger containing a package of metal flat and corrugated sheets with the formation of channels for working environments (see USSR author's certificate No. 1483232, IPC 4 F28D 9/00, 05/30/1989).

This heat exchanger does not provide the necessary strength of the product at high temperatures (800 ° C or more) and has a significant mass due to the high density of up to 8.5 g / cm ³ .

The closest to the proposed device for the combination of essential features is a cross-type heat exchanger containing a housing inside which is installed a package of dividing flat sheets alternating with cross-sectioned corrugated sheets (see US patent No. 4789585, NKI 428/186, 165 / 134.1, 165 / 165, December 6, 1988).

The well-known heat exchanger is made using paper technology from ceramic paper with a thickness of 1 mm, which, due to the low strength during thermal cycling, does not provide the necessary strength of the product at high (800 ° C or more) temperatures.

There is a known method of manufacturing honeycomb structures in which a corrugated sheet of a composite material of fiberglass, organoplastics or carbon fiber is obtained by corrugation in rolls, some of which are thermofixed, subjected to heating to 160-180 ° C (see the Handbook of composite materials, ed. J.Lyubina. - M.: Mechanical Engineering, 1988. - 584 p.).

This manufacturing method does not provide high-temperature corrugated sheet, because is carried out at the temperature of curing of the polymeric binder, at which its thermal degradation does not occur. When the processing temperature is increased to the decomposition temperatures of the polymer matrix (600-1000 ° C), the accuracy of the corrugation profile formed in the rolls is not ensured due to its inevitable shrinkage.

Closest to the proposed method for the combination of essential features is a method of manufacturing a corrugated sheet of non-metallic material, comprising forming a plate with the formation of corrugations with subsequent heating (see US patent No. 4108938, IPC B01D 67/00, B29C 53/22, 08/22/1978 g .).

The known method does not provide corrugated sheets for a heat exchanger from a composite material that retain strength at high temperatures and have a low density.

The objective of the group of inventions is to create a heat exchanger from a composite material with a reduced density, which can be used at high temperatures.

The technical result when using the proposed group of inventions is to increase the strength of the heat exchanger made of composite material for use at high temperatures while reducing its mass.

The specified technical result in terms of the method of manufacturing a heat exchanger from composite material is achieved by the fact that in the method of manufacturing a heat exchanger, which includes cutting the size of corrugated and dividing flat sheets made of composite material, assembling the corrugated and dividing flat sheets in a package with the cross direction of the corrugations in adjacent layers , subsequent heat treatment and installation in the housing, before assembling the place of contact of the sheets on the tops of the corrugations of the corrugated sheets, grease high mperaturnym adhesive for bonding the sheet to the separating plane and corrugated sequentially performed after assembling high temperature curing adhesive and heat treating the package at a temperature of 800-1900 ° C, and then produce a ceramic package seal component.

In addition, curing of the high temperature adhesive is carried out using pressure.

The specified technical result in part of the device is achieved due to the fact that in the heat exchanger containing the housing, inside which is installed a package of dividing flat sheets alternating with cross-sectioned corrugated sheets, corrugated sheets and dividing flat sheets are rigidly interconnected at the points where the sheets touch the vertices corrugation and made of the same high-temperature composite material, the strength of which is ensured by the use of fibrous filler.

In addition, the heat exchanger body is made of high temperature composite material; the heat exchanger is equipped with lateral clamps made of a composite of the type C-SiC or SiC-SiC.

The specified technical result in terms of the method of manufacturing a corrugated sheet for a heat exchanger is achieved by the fact that in the method of manufacturing a corrugated sheet for a heat exchanger, comprising forming a plate with the formation of corrugations with subsequent heating, before forming the plate, which is a prepreg, on the base surface with a profile that accurately reproduces the the contour of the molded corrugated sheet, apply glue for bonding dissimilar materials and sequentially, from one end of the base to the other, the prepreg is glued to the surface of the corrugated base, then the prepreg is pressed onto the corrugated base plate with the corrugated pressure plate and the base is subjected to a corrugated carbonization sheet.

In addition, the prepreg is made on the basis of carbon fabric, or fiberglass, or fabric from oxide, nitride, carbide fibers, silicon carbide fibers, followed by impregnation or a thermoset or organosilicon binder.

Figure 1 shows a heat exchanger, a General view;

figure 2 shows the layout of the corrugated sheet on the base with a clip.

Corrugated sheet 1 of composite material contains protrusions and depressions, while the lower part of the cross section of the molded section of the zigzag corrugation is identical to the curve of the corrugated surface of the base 2. The corrugation has an arbitrary size. The corrugated sheet 1 of the composite material is made of prepreg obtained by impregnating the filler in the form of either carbon fabric or fiberglass or organotissue with an organic binder based on phenol-formaldehyde resin. Instead of a binder based on phenol-formaldehyde resin, a binder based on polycarbosilanes, siloxanes, silicones can be used - any organic substances that form a significant amount of inorganic coke residue as a result of pyrolysis (thermal decomposition).

A device for manufacturing a corrugated sheet contains a base 2 and a corrugated pressure plate 3 for pressing and fixing the profile of the corrugations (figure 3). The distance "a" (slotted opening) between the connected forming and fixing surfaces, respectively, of the base 2 and the pressure plate 3 is equal to the thickness of the prepreg. To reduce the difference in thermal expansion between the material of the base 2, the pressure plate 3 and the molded corrugated sheet 1, the base 2 and the plate 3 can be made of graphite or a carbon-carbon composite.

A method of manufacturing a corrugated sheet of composite material is as follows.

According to the invention, for the manufacture of a corrugated sheet, a preform in the form of a prepreg is used, which is made on the basis of carbon fabric, or fiberglass fabric, or fabric from oxide, nitride, carbide fibers, silicon carbide fibers, followed by impregnation or thermoset or organosilicon binders and drying.

On the forming surface of the base 2, glue is applied and sequentially, from one end to the other, the workpiece is pressed against the surface of the corrugation of the base 2 until the prepreg completely adheres to the forming surface and fills all the corners of the profile. Then, by means of the pressure plate 3, the corrugated plate is pressed to the corrugations of the base, fixed and subjected to base 2 with the corrugated sheet 1 and the carbonization plate 3 to temperatures of thermal degradation of the organic binder (carbonization) of at least 800 ° C.

Next, the base 2 with the corrugated sheet 1 is cooled and the corrugated sheet 1, which has a strictly defined height corrugation profile with exactly the same height, is easily removed from the carbonized prepreg.

Example 1

On the forming surface of the base 2, glue is applied and sequentially, from one end to the other, the workpiece is pressed against the surface of the corrugation of the base 2 until the prepreg completely adheres to the forming surface and fills all the corners of the profile. Then, by means of the pressure plate 3, the corrugated plate is pressed to the corrugations of the base and the base 2 is subjected to the corrugated sheet 1 and the carbonization plate 3 at a temperature of 800 ° C. Next, the assembly is cooled and the corrugated sheet 1 having a precisely defined height profile is easily removed.

To make the next corrugated sheet 1, the process is repeated.

A heat exchanger comprising a housing 4, inside of which there is a package of dividing flat sheets 5, alternating with cross-arranged corrugated sheets 1, and side clips 6. The corrugated sheets 1 and dividing flat sheets 5 are rigidly interconnected at the places where the sheets touch the corrugation vertices and are made from the same high-temperature composite material with the formation of channels for hot and cold air. Sheets 1 and 5 are made of ceramic composite material with a fibrous reinforcing filler.

The heat exchanger body 4 is made of a high temperature composite material; in addition, the function of the heat exchanger housing can be performed, for example, by flanges located on both sides of the stack of dividing flat sheets 5, alternating with cross-sectioned corrugated sheets 1.

Side latches 6 are located on the edges of the separating flat sheets 5 and are designed to prevent the erosive effects of compressed air flows directly on the edge regions of the corrugations, as well as to ensure the strength of the heat exchanger package. Side clips 6 are made of high temperature composite, for example, type C-SiC or SiC-SiC.

The package is designed for cross-type heat exchangers for cooling hot air or gases with a temperature of up to 900 ° C and a pressure of up to 1.5 MPa with air coming from a fan or high-speed head when moving an object. Heat transfer between hot and cold fluids is carried out through the surfaces of corrugated sheets 1 and dividing flat sheets 5.

The heat exchanger operates as follows.

For cooling, a hot heat carrier, for example gas, is evenly distributed over all channels that have corrugated sheet 1. Cold heat carrier, for example, air from a pressure device (not shown in the drawing) enters another row of channels of corrugated sheets perpendicular to the first. As the hot gas passes through the channels between the corrugated and separation sheets, the gas gradually cools. Heat transfer between hot and cold fluids is carried out by the heat conduction mechanism at the contact points of corrugated sheets 1 and separating flat sheets 5, and also, especially when the working temperature of the heat exchanger increases, directly through the surface of corrugated sheets 1 and separating flat sheets 5 by the radiation mechanism. After cooling the hot heat carrier to the desired temperature, the heat exchanger is turned off, if necessary, the process is repeated.

A method of manufacturing a heat exchanger is as follows.

According to the invention, for the manufacture of a heat exchanger, blanks are used in the form of corrugated sheets 1 and dividing flat sheets 5 of the same composite material, which must be cut to size in accordance with the dimensions of the heat exchanger package.

A preliminary separating flat sheet 5 is made of a prepreg cut into pieces, which is pressed between plates of a heated hydraulic press at a temperature of up to 180 ° C and a pressure of up to 5 MPa. To eliminate adhesion to the press plates between the prepreg and the plates, a fluorinated fabric is laid (not shown in the drawing). Then all the blanks for sheet 5 are placed in a carbonizer, where they conduct non-oxidative annealing of the blanks in the temperature range of 20-1000 ° C. Next, carbonized blanks for sheet 5 are cut into the final geometric size and transferred to the stage of assembly of the heat exchanger package.

After cutting the contact points of sheets 1 (along the corrugation tops) and 5, grease them with high-temperature glue and collect sheets 1 and 5 into a bag, arranging sheets 1 taking into account the cross direction of the corrugations in adjacent layers of the bag. The curing of the high temperature adhesive is carried out using pressure.

The collected package is subjected to heat treatment in a non-oxidizing atmosphere in the temperature range 800-1900 ° C, and then the package is sealed with a ceramic component.

After heat treatment and sealing, the assembled package is placed in the heat exchanger body 4, fixed and mounted on the vehicle for subsequent operation.

Example 2

After cutting the places where sheets 1 and 5 touch the tops of the corrugations, the sheets 1 are greased with high-temperature glue for gluing sheets 5 and sheets 1 and 5 are collected in a bag, placing sheets 1 taking into account the cross direction of the corrugations in adjacent layers of the package, and the curing of high-temperature glue is carried out using pressure for example 5 MPa.

The assembled package is subjected to heat treatment at a temperature of 1900 ° C, then the package is sealed with a ceramic component, for example, silicon carbide from the gas phase of methylsilane at a temperature of 700 ° C.

In the case of an increase in the heat treatment temperature of the heat exchanger package above 1900 ° C, partial decomposition of the components of high-temperature glue (for example, silicon carbide) occurs and the heat exchanger package loses its necessary strength, including when used at high temperatures.

After heat treatment and sealing, the assembled package is installed in the heat exchanger body 5.

Example 3

After cutting the places where sheets 1 and 5 touch the tops of the corrugations, the sheets 1 are greased with high-temperature glue for gluing sheets 5 and sheets 1 and 5 are assembled into a bag, placing sheets 1 taking into account the cross direction of the corrugations in adjacent layers of the package, and the curing of high-temperature glue is carried out using pressure for example 1 MPa.

The collected package is subjected to heat treatment at a temperature of 800 ° C, then the package is sealed with a ceramic component, for example, silicon carbide from the liquid phase of polycarbosilane in the temperature range of 250-1000 ° C.

In the case of a decrease in the heat treatment temperature of the heat exchanger package below 800 ° C, the processes of formation of high-temperature components of the adhesive do not fully proceed in the latter, as a result of which it does not have sufficient strength when used at high temperatures.

After heat treatment and sealing, the assembled package is installed in the housing 4 of the heat exchanger.

Example 4

After cutting the places where sheets 1 and 5 touch the tops of the corrugations, the sheets 1 are greased with high-temperature glue for gluing sheets 5 and sheets 1 and 5 are assembled into a bag, placing sheets 1 taking into account the cross direction of the corrugations in adjacent layers of the package, and the curing of high-temperature glue is carried out using pressure , for example, 4 MPa.

The collected package is subjected to heat treatment at a temperature of 1250 ° C, then compaction with a ceramic component, for example, silicon nitride from the polysilazane liquid phase in the temperature range 150-1000 ° C.

After heat treatment and sealing, the assembled package is installed in the housing 4 of the heat exchanger.

To make the next heat exchanger, the process is repeated.

The use of the claimed group of inventions in the production of heat exchangers from composite materials can increase the strength of the heat exchanger at temperatures above 600 ° C while reducing weight by at least 100%.

Claims (9)

1. A method of manufacturing a heat exchanger, including cutting the size of the corrugated and separating flat sheets made of composite material, assembling the corrugated and separating flat sheets in a bag with the corrugation of the corrugations cross in adjacent layers, subsequent heat treatment and installation in the housing, characterized in that before assembly the places where the sheets touch the tops of the corrugations of the corrugated sheets are lubricated with high-temperature glue to adhere the dividing flat sheets to the corrugated sheets and subsequently after the assemblies cure the high-temperature glue and heat treat the bag at a temperature of 800-1900 ° C, and then seal the bag with a ceramic component. 2. The method according to claim 1, characterized in that the curing of the high-temperature adhesive is carried out using pressure. 3. A heat exchanger made of composite materials, comprising a housing, inside which a package of dividing flat sheets is installed, alternating with cross-sectioned corrugated sheets, characterized in that the corrugated sheets and dividing flat sheets are rigidly interconnected at the places where the sheets touch the corrugation vertices and are made of the same high-temperature composite material. 4. The heat exchanger according to claim 3, characterized in that the housing of the heat exchanger is made of high temperature composite material. 5. The heat exchanger according to claim 3, characterized in that it is equipped with side clips made of a composite of the type C-SiC or SiC-SiC. 6. A method of manufacturing a corrugated sheet for a heat exchanger, comprising forming a plate with the formation of corrugations, followed by heating, characterized in that before forming the plate, which is a prepreg, on the surface of the base with a profile that accurately reproduces the inner contour of the molded corrugated sheet, apply adhesive for bonding heterogeneous materials and sequentially, from one end of the base to the other, glue the prepreg to the surface of the corrugated base, then the corrugated pressure plate pre pop prepreg base to the flutes and is heated to carbonize the corrugated prepreg. 7. The method according to claim 6, characterized in that the prepreg is made of carbon fabric, or fiberglass, or fabric of oxide, nitride, carbide fibers and silicon carbide fibers, followed by impregnation with either a thermoset or organosilicon binder, and drying. 8. The method according to claim 6, characterized in that the corrugated base and the corrugated pressure plate are made of graphite or a carbon-carbon composite. 9. The method according to claim 6, characterized in that the width of the slotted opening between the connected base and the pressure plate is equal to the thickness of the prepreg.

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