Patent Grant
10775106
This application claims priority under Section 119 from German Patent Application No. 102017100460.2 filed Jan. 11, 2017, which is hereby incorporated by reference in its entirety.
The invention relates to a device for heat exchange, in particular in a refrigerant circuit, with at least one first flow path and at least one second flow path, which, in a cross section perpendicular to a longitudinal direction of the device, are disposed coaxially with respect to one another, and each of which comprises at least one flow channel. The device is realized of a synthetic material.
Due to their large number, the demands inter alia made quite generally of the technical components of modern motor vehicles are, at least at constant or greater efficiency, minimizing weight as well as volume in order to limit, on the one hand, the fuel consumption and, on the other hand, to ensure the desired functionality by installing all components in the low designed space of the motor vehicle. The implementation and disposition of the components must be combined in a manner that saves space and costs.
Specifically for conditioning the air of the passenger compartment, motor vehicles disclosed in prior art comprise an air-conditioning system with a refrigerant circuit. To raise the efficiency during operation, expressed as coefficient of performance, as well as to increase the cooling capacity, the refrigerant circuit, dependent on the refrigerant, is implemented with a so-called internal heat exchanger. For example, separate coaxial tube heat exchangers or plate heat exchangers are employed as internal heat exchangers as well as combined components, comprised of an accumulator or an evaporator, each with an internal heat exchanger.
By internal heat exchanger is here understood a heat exchanger internal to the refrigerant circuit, which serves for heat transfer between the refrigerant at high pressure and the refrigerant at low pressure. After condensation or liquifaction, the liquid refrigerant is herein further cooled, on the one hand, and, on the other hand, the suction gas is superheated before entering a compressor. Heat is transferred from the refrigerant at high pressure to the refrigerant at low pressure.
Conventional coaxial tube heat exchangers are primarily constructed of aluminum and are operated according to the counter flow principle which ensures good heat transfer and efficient heat exchange with the least possible temperature differences.
In order to reduce in particular the weight as well as the cost of production of the components of a refrigerant circuit, the use of synthetics as their material is currently pursued. In some motor vehicles, for example, the high-pressure line of the refrigerant circuit is already produced of synthetic material.
The material-specific properties of the synthetic and of the refrigerant at high-pressure permit using an approximately identical design of the high-pressure line of synthetic material, in particular of the connection of peanut fittings as connection technology with the tube.
The weight as well as also the cost of the production would increase markedly if a similar design of the coaxial tube heat exchanger were realized of a synthetic material compared to a realization of aluminum. The wall thicknesses of conventional coaxial tube heat exchangers of aluminum are low. The tube charged with refrigerant at low-pressure is constructed with a large diameter. When transferring the diameter to a tube developed of a synthetic material, in particular a plastic material, the wall thickness, and therewith also the weight, increases considerably.
KR 2004 0027744 A discloses a synthetic double tube implemented of an outer tube and an inner tube disposed coaxially with the outer tube. The synthetic double tube comprises fins which, oriented perpendicularly to the outer circumference of the inner tube and to the inner circumference of the outer tube, extend between the inside of the outer tube as well as the outside of the inner tube and are disposed at uniform spacing on the circumference. The inner tube with its inner radius has a circular continuous first flow cross section while the second flow cross section between the inner tube and the outer tube is divided by the fins into sections of identical size.
JP 3059203 also discloses a double tube developed of an outer tube and an inner tube disposed coaxially with the outer tube. The outer tube is produced of a pressure-resistant material and the inner tube is produced of a synthetic material. The inner tube has a continuous first flow cross section while the second flow cross section between the inner tube and the outer tube is divided by centering elements disposed spaced apart in the direction of the longitudinal axis as well as also over the circumference.
The invention addresses the problem of providing a device for the heat exchange in particular in a refrigerant circuit for internal heat exchange. The cost of production and the weight of the device are to be minimal, specifically in comparison with devices of aluminum. The constructed size of the device is also to be minimal. The device is to be operatable at maximal efficiency, with the efficiency of the process of heat exchange to be within the range of the efficiency of the devices of aluminum.
The problem is resolved through the subject matters with the characteristics of the independent patent claims. Further developments are specified in the dependent patent claims.
The problem is resolved through a device according to the invention for heat exchange, in particular in a refrigerant circuit, for example an air-conditioning system of a motor vehicle. The device is implemented with at least one first flow path and at least one second flow path which, in a cross section perpendicular to a longitudinal direction of the device, are disposed coaxially with respect to one another, with each having at least one flow channel. A wall of the at least one flow channel of at least one flow path is herein implemented of a synthetic material.
According to the concept of the invention, the flow paths are each implemented of a multiplicity of flow channels. By multiplicity is here to be understood a number of at least two.
The device advantageously has a cylindrical shape, in particular a circular cylindrical shape, with a circular cross section in the longitudinal direction. The cross section can herein also be developed in different shapes. It can, for example, have the shape of a trapezoid, a triangle, an oval, an ellipse, a rectangle or the like. In addition, cross sections of combinations of different shapes are also feasible.
According to a further development of the invention, at least one flow path is implemented of a multiplicity of flow channels, each with a circular flow cross section. The flow cross sections can have different diameters.
A wall of a flow path, in particular that of the at least one flow channel of the at least one second flow path, is advantageously realized of a metal, in particular of aluminum. The entire device is alternatively comprised of a synthetic material. Among the synthetic materials are polyamides including aliphatic, aromatic as well as also long-chain aromatic polymers in general and polypropylene.
To improve the heat transfer properties, walls of the flow paths, furthermore, can also be implemented of a combination of synthetic material and metal or metal alloys. The feasibility is herein given that, to improve the heat transfer properties, a first portion of the walls is realized of a combination of synthetic material and metal or metal alloy as well as a second portion of the walls of a metal, in particular aluminum.
According to a first alternative implementation, each flow channel is developed with a separate wall. Herein the walls of adjacently disposed flow channels are in contact with one another.
According to a second alternative implementation each flow channel is delimited by a wall, wherein in each instance adjacently disposed flow channels are separated from one another by a common wall.
According to an advantageous implementation of the invention, a first flow path, disposed in the proximity of an axis of symmetry of the device, has a circular shape in cross section. The flow channels of a second flow path are disposed coaxially about the first flow path and have in their entirety a circular ring shape. In the implementation of a multiplicity of flow channels of the first flow path in the proximity of the axis of symmetry of the device, these flow channels have in their entirety a circular shape.
Starting from the axis of symmetry toward the outside, flow channels of a first flow path are preferably disposed coaxially about flow channels of a second flow path which, in their entirety, have the shape of a circular ring. Therewith at least one second flow path is disposed such that it is delimited by two first flow paths. Moreover, flow channels of a further second flow path can be disposed coaxially about flow channels of a first flow path which, in their entirety, again have a circular ring shape.
The flow channels are herein advantageously disposed in a single row or in multiple rows. By multiple rows is here to be understood a number of at least two rows.
In the longitudinal direction the flow channels are preferably disposed such that they are aligned parallel to one another.
A further advantageous implementation of the invention comprises that at least one flow path, in a cross section perpendicular to the longitudinal direction, is circular ring-shaped, wherein the flow path is divided into partial circular ring-shaped flow channels by webs oriented in the direction of a radius. In the webs can be developed flow channels which preferably have circular flow cross sections.
According to a further development of the invention, in each of the front faces of the device a connection element for the first flow path and a connection element for the second flow path or a combination connection element for the flow paths is disposed, in which are disposed connection flow channels continuing the flow channels of the first flow paths in the longitudinal direction and at least one ring channel is implemented as a connection flow channel of the second flow paths. The at least one ring channel connects the volumes of the second flow channels with one another.
The ring channel, moreover, advantageously comprises an outlet opening into which a connection line opens out. The connection line is preferably disposed at an angle perpendicular to the longitudinal direction.
The advantageous implementation of the invention, in particular in view of constructed size and weight, permits the use of the device as an internal heat exchanger in a refrigerant circuit, in particular in an air-conditioning system for conditioning the air of a passenger compartment of a motor vehicle. In the internal heat exchanger heat is transferred between the refrigerant at high-pressure level and the refrigerant at low-pressure level. Depending on the implementation of the device, in a feasible combination of the materials synthetic and metal, in particular aluminum, the refrigerant at high-pressure level is conducted through the components of aluminum and the refrigerant at low-pressure level through the components of synthetic material or the refrigerant at high-pressure level is conducted through the components of synthetic material and the refrigerant at low-pressure level through the components of aluminum.
The employment of aluminum serves also for the improvement of heat conduction. The employment of synthetic material on the outside of the device, i.e. the side in contact with the surroundings, decreases the heat loss or the heat input and therewith the heat exchange with the ambient surroundings. Herein the refrigerant at high-pressure level with higher temperature than the refrigerant at low-pressure level is preferably conducted in the outer region of the device since the refrigerant at high-pressure level most frequently is also warmer than the adjacent surroundings.
In summary, the device according to the invention for heat exchange in a motor vehicle comprises further diverse advantages:
Further details, features and advantages of embodiments of the invention are evident in the following description of embodiment examples with reference to the associated drawing. Therein depicts in each Figure a device for heat exchange with first and second flow paths disposed coaxially with respect to one another:
In
The flow paths 2a, 3a are each implemented with flow channels 4a, 5a that are circular in cross section. The flow channels 4a of the first flow path 2a form a circular flow path and the flow channels 5a of the second flow path 3a are disposed in the form of a circular ring about the first flow path 2a. The flow channels 4a of the first flow path 2a are identical as are the flow channels 5a of the second flow path 3a, wherein the flow channels 4a of the first flow path 2a can differ from the flow channels 5a of the second flow path 3a. The differences refer in particular to the free flow cross sections as well as the wall thicknesses and therewith to the inner and outer radii or the diameters.
As the throughflow areas, the free cross sections of the flow paths 2a, 3a can correspond approximately to the throughflow areas of the coaxial tubes of aluminum known within prior art.
The flow channels 4a, 5a extend in a straight line and parallel along the longitudinal direction L. According to an embodiment, not shown, the flow channels 4a, 5a are disposed in the longitudinal direction L turned or twisted about a center axis of the device.
According to a second embodiment, not shown, the number of flow channels 4a per circle remains constant with increasing distance from the center, wherein the outer radii of the flow channels 4a increase with increasing distance from the center axis.
In the device 1a depicted in
As the flow channels 4a of the first flow path 2a, the flow channels 5a of the second flow path 3a can each be disposed in the first or the second embodiment, wherein the flow channels 5a of the second flow path 3a can also be disposed in the first embodiment and the flow channels 4a of the first flow path 2a in the second embodiment, or conversely. The different embodiments refer herein to the formation of the diameters of the flow channels depending on the distance from the center axis.
In contrast to the device 1a of
In the direction of the radius of the device 1b the first flow paths 2b are each implemented as circular rings with the width of one flow channel 4b, i.e. implemented of one flow channel 4a, while the second flow paths 3b are implemented with the width of two flow channels 5b, i.e. implemented of two flow channels 5b. Each first flow path 2b is therewith encompassed by two flow channels 5b of the second flow path 3b. The flow channels 5b of the second flow paths 3b, adjacently disposed in the direction of the radius of device 1b, are disposed in contact with one another.
The flow paths are disposed, starting at the center toward the outside, in the sequence first flow path 2b, second flow path 3b, first flow path 2b, second flow path 3b, first flow path 2b as well as second flow path 3b.
The total throughflow area of the first flow paths 2b is in the range of 180 mm to 450 mm2, in particular in the range, for example, of 200 mm2 to 420 mm2, specifically in the range of 300 mm2 to 420 mm2, while the total throughflow area of the second flow paths 3b is in the range of 40 mm2 to 100 mm2, in particular approximately 50 mm2 or 70 mm2, specifically in the range of 45 mm2 to 63 mm2.
When operating the device 1b as internal heat exchanger of a refrigerant circuit, the first flow paths 2b are passed through by refrigerant at low-pressure level and the second flow paths 3b by refrigerant at high-pressure level. Due to the material-specific properties of the refrigerant on the high-pressure side, the requisite total throughflow area is herein markedly lower on the high-pressure side than the requisite total throughflow area on the low-pressure side.
A flow channel 4b of the first flow path 2b has an inner diameter in the range of 0.8 mm to 1.5 mm, preferably of 1.2 mm, and a wall thickness in the range of 0.1 mm to 0.3 mm, preferably of 0.2 mm. A flow channel 5b of the second flow path 3b is also developed with an inner diameter in the range of 0.8 mm to 1.5 mm, preferably of 1.2 mm, as well as a wall thickness in the range of 0.2 mm to 0.6 mm, preferably of, for example, 0.4 mm, specifically of 0.37 mm.
The device 1b has an outer diameter in the range of 20 mm to 30 mm, preferably in the range of 22 mm to 27 mm, specifically in the range of 24 mm to 26 mm, and is scalable in size, in particular in total diameter. The configuration, or the number of flow paths 2b, 3b, and that of the flow channels 4b, 5b forming the flow paths 2b 3b, can herein be varied.
In
The essential difference from the device 1b of
On the outside as well as also on the inside, the flow channels 5c of the second flow paths 3c are in direct thermal contact with a flow channel 4c′ of the first flow paths 2c. The flow channels 4c′, 5c, disposed adjacently in the direction of the radius of device 1c′, of a type of flow path 2b, 3b are disposed such that they are not in contact with one another. The terms outside and inside always refer to the outer wall of the flow channels 4c′, 5c depending on the radius of the device 1c′.
Maintaining the flow channels 5c, circular in cross section, of the second flow paths 3c, the flow channels 4c of the first flow paths 2c have to be adapted.
At the contact sides with the flow channels 5c, the wall of flow channel 4c is herein adapted to the wall of the flow channels 5c and formed concavely such that the walls of the adjacently disposed flow channels 4c, 5c are fully in contact over their entire area. The radii of the outsides of the walls of the flow channels 4c, 5c are identical.
The walls of flow channels 4c at the contact sides with one another, i.e. in the circumferential direction, are planar and are also fully in contact with one another over their entire surface. The planar walls are each preferably oriented in the direction of the radius of device 1c.
When operating the device 1c as internal heat exchanger of a refrigerant circuit, the flow channels 4c, adapted in cross section, of the first flow paths 2c are passed through by refrigerant at low pressure level and the circular flow channels 5c of the second flow paths 3c by refrigerant at high pressure level.
Herein, furthermore, the disposition of the flow channels 4c, 5c of device 1c according to
The devices 1a, 1b, 1c according to
In
The device 1d is comprised of several circular cylindrical tubes disposed coaxially, wherein the flow paths 2d, 3d, from the inside out, are in each instance disposed such they are alternatingly adjacent. Between the adjacent tubes are developed fins or webs distributed uniformly over the circumference. The fins or webs, disposed in the direction of the radius of device 1d, divide the flow paths 2d, 3d into the flow channels 4d, 5d, each of which is delimited in the circumferential direction by a tube wall and in the direction of the radius by a fin.
In comparison with the devices 1a, 1b, 1c according to
The essential difference from the device 1d of
The embodiments of the devices 1d, 1e according to
To distribute the fluid mass flow, between which the heat is to be transferred, for example when operating the device 1a, 1b, 1c, 1d, 1e as internal heat exchanger of a refrigerant circuit, between the refrigerant mass flows at high-pressure level and at low-pressure level, onto the individual flow channels 4a, 4b, 4c, 4d, 4e, 5a, 5b, 5c, 5d, 5e and to combine them again after they have passed through the device 1a, 1b, 1c, 1d, 1e, connection components are to be provided.
The connection elements 6, 6f, 7, 7f, and the combination connection elements 11g, 11h, 11i, respectively, are each connected with one another and with the device 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i for example by means of adhesion, deforming, friction welding or welding. The connection elements 6, 6f, 7, 7f or the combination connection elements 11g, 11h, 11i advantageously comprise peanut fittings as connection elements to the connection lines.
As shown in
Depending on the direction of flow, the first fluid mass flow flowing into the first flow paths 2f is conducted through the connection element 6, 6f to the connection element 7, 7f and in the connection element 7, 7f distributed onto the flow channels 4f of the first flow paths 2f or the first fluid mass flow flowing out of the flow channels 4f of the first flow paths 2f is conducted through the connection element 7, 7f to the connection element 6, 6f and is mixed in the connection element 6, 6f. The connection element 6, 6f is connected with a connection line, not shown, to conduct the first fluid mass flow. Depending on the direction of flow, the second fluid mass flow flowing into the second flow paths 3f is distributed in the connection element 7, 7f onto the flow channels 5f of the second flow paths 3f or the second fluid mass flow flowing out of the flow channels 5f of the second flow paths 3f is conducted through the connection element 7, 7f and is mixed in a connection line 8 for conducting the second fluid mass flow. The connection line 8 is connected with the connection element 7, 7f.
The essential differences from the device 1e of
At its core the connection element 7f has honeycomb-shaped connection flow channels 9f, which are developed and disposed such as to continue the flow channels 4f of the first flow paths 2f in the longitudinal direction L. The front faces in contact with one another of the device 1f and of the connection element 7f are identical in size and disposition of the honeycomb-shaped flow channels 4f and of the connection flow channels 9f, such that the flow channels 4f are extended through the connection element 7f up to the connection element 6f. Starting from the front face oriented toward the device 1f, the connection flow channels 9f taper on the way through the connection element 7f. In the connection element 6f the first fluid is distributed or mixed, depending on the direction of flow.
About the connection flow channels 9f disposed in the core a ring channel is realized as connection flow channel 10f of the second flow paths 3f, which ring channel is open in the direction toward the front face of the connection element 7f and encompasses, together with the circular flow channels 5f of the second flow paths 3f, a common volume. At the front faces of the device 1f and of connection element 7f the flow paths 3f open out into the common ring channel. The ring channel, in turn, is provided with an outlet opening which is disposed substantially perpendicularly to the longitudinal direction L and into which leads the connection line, not shown. In the ring channel of connection element 7f the second fluid is distributed or mixed, depending on the direction of flow.
Similarly to the device 1d of
In contrast to the device 1d of
In the longitudinal direction L the combination connection element 11g comprises continuous connection flow channels 9g, which are implemented and disposed such that they continue the flow channels 4g of the first flow paths 2g. In the proximity of the fins of device 1g the combination connection element 11g is developed with webs which extend from the outer wall in the direction of the radius up to the height of the wall of the inner tube and, in the proximity of the center, in particular in the proximity of the inner tube as a first flow path 2g, leave open the flow path 2g.
The webs are disposed on the front faces, oriented toward one another, of the device 1g and of the combination connection element 11g spaced apart from the fins of the device 1g such that the flow channels 4g developed in the fins, also open out into the volume left open by the webs. The first fluid flows substantially in the longitudinal direction L through the combination connection element 11g and, depending on the direction of flow, is distributed onto the flow channels 4g or the first fluid, flowing through the flow channels 4g, is at least partially mixed in the combination connection element 11g, flows subsequently through the combination connection element 11g and is lastly mixed after the webs.
The combination connection element 11g comprises about the connection flow channels 9g, disposed in the core, as well as at the ends of the webs at the height of the wall of the inner tube, a ring channel as the connection flow channels 10g of the second flow paths 3g, which are open in the direction toward the front face of the combination connection element 11g and, through channels formed in the webs encompass together with the circular flow channels 5g of the second flow paths 3g of the device 1g, a common volume. The flow paths 3g, developed in the wall of the inner tube, open at the front faces of the device 1g and of the combination connection element 11g out into an inner ring channel and the flow paths 3g developed in the wall of the outer tube open at the front faces of the device 1g and of the combination connection element 11g out into an outer ring channel. The inner ring channel and the outer ring channel are fluidically connected with one another via the channels developed in the webs. The outer ring channel, in turn, is provided with an outlet opening which is oriented substantially perpendicularly to the longitudinal direction L and into which lead connection lines, not shown. In the ring channels of the combination connection element 11g the second fluid is either distributed or mixed depending on the direction of flow.
In contrast to the device 1g of
The combination connection element 11h in a cross section comprises in its core a central circular connection flow channel 9h and rectangular connection flow channels 9h disposed about the central connection flow channel 9h, which are developed and disposed such that they continue the flow channels 4h of the first flow paths 2h in the longitudinal direction L. The front faces of the device 1h and of the combination connection element 11h in contact with one another are identical in terms of size and disposition of the flow channels 4h and connection flow channels 9h or they are at least nearly identical, such that the flow channels 4h are extended into the combination connection element 11h. The connection flow channels 9h end within the combination connection element 11h and open out into a common volume. In the combination connection element 11h the first fluid is distributed or mixed depending on the direction of flow. In the proximities of the fins of device 1h the combination connection element 11h is provided with webs which extend from the outer wall in the direction of the radius up to a circular ring disposed in the proximity of the wall of the inner tube of the device 1h. In the proximity of the inner tube the circular ring comprises a connection flow channel 9h with circular flow cross section as a first flow path 2h. At the front faces of the device 1h and of the combination connection element 11h the webs and the circular ring are in contact on the fins and the inner tube of the device 1h.
The combination connection element 11h comprises one ring channel each about the connection flow channels 9h, disposed in the core, as well as in the interior of the circular ring as connection flow channels 10h of the second flow paths 3h, which, like the webs, are open in the direction of the front face of the combination connection element 11h and, with the channels developed in the webs and the circular flow channels 5h of the second flow paths 3h of the device 1h, encompass a common volume. The flow paths 3h developed in the wall of the inner tube open at the front faces of the device 1h and of the combination connection element 11h out into an inner ring channel and the flow paths 3h developed in the wall of the outer tube, open at the front faces of the device 1h and of the combination connection element 11h out into an outer ring channel. The flow paths 3h developed in the fins open each at the front faces of device 1h and of the combination connection element 11g out into a channel developed in a web.
The inner ring channel and the outer ring channel are, moreover, fluidically connected with one another across the channels developed in the webs. The outer ring channel is provided with an outlet opening which is oriented substantially perpendicularly to the longitudinal direction L and into which the connection line, not shown, opens out. In the ring channels and in the channels developed in the webs of the combination connection element 11h the second fluid is distributed or mixed depending on the direction of flow.
In contrast to the device 1e of
The combination connection element 11i corresponds substantially to the combination connection element 11h of
The devices 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i are in particular directed at heat exchangers developed as coaxial tube heat exchangers, wherein the utilized mechanisms, materials and designs are also applicable to other types of heat exchangers.
The devices 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i permit their employment as internal heat exchangers of a refrigerant circuit which is employable for diverse refrigerants such as R1234yf, R1234ze, R134a, R290, R600a, R600, R717, R744, R32, R152a, R1270, R1150 and their mixtures.
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|---|---|---|---|
| 10 2017 100 460 | Jan 2017 | DE | national |
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| 20120222845 | Kinder | Sep 2012 | A1 |
| Number | Date | Country |
|---|---|---|
| 3614342 | Oct 1987 | DE |
| 102007044980 | Mar 2008 | DE |
| 102012100722 | Sep 2012 | DE |
| 3059203 | Jul 1999 | JP |
| 2010096225 | Apr 2010 | JP |
| 20040027744 | Apr 2004 | KR |
| Number | Date | Country | |
|---|---|---|---|
| 20180195806 A1 | Jul 2018 | US |
