RU2735768C1 - Heat recuperation device - Google Patents

Abstract

FIELD: heat exchange.

SUBSTANCE: invention relates to heat medium heat recuperation device, which comprises heat exchanger system (1) with central flow channel (3), surrounded by at least one edge flow channel (2), wherein inside the edge flow channel (2) there is at least one heat exchange element (4), by means of which during operation of the waste heat source heat from the heating medium created by the waste heat source, can be transferred to current through heat exchange element (4) working medium, and central flow channel (3), as well as edge flow channel (2) have, each, at least one inlet (5, 6) for inlet of heating medium. Besides, edge flow channel (2) comprises at least two flow chambers (8) separating edge flow channel (2) perpendicular to central axis (7) of heat exchanger system (1).

EFFECT: device for heat recovery is disclosed.

9 cl, 1 dwg

Description

The invention relates to a device for recovering heat from an exhaust gas flowing through the exhaust tract of an internal combustion engine, which comprises a heat exchanger system with a central flow channel surrounded by at least one edge flow channel. In this case, at least one heat exchange element is located inside the edge flow channel, by means of which, during operation of the internal combustion engine, heat from the exhaust gas generated by the internal combustion engine can be transferred to the working medium flowing through the heat exchange element. In addition, the central flow channel as well as the edge flow channel each have at least one exhaust gas inlet. In this case, the edge flow channel has at least two flow chambers dividing the edge flow channel perpendicular to the central axis of the heat exchanger system, and the device downstream of the outlet of the central flow channel and / or the outlet of the edge flow channel has a channel seal by means of which the volume flow can be controlled waste gas through a central flow channel and / or an edge flow channel.

A device of this type is described in DE 10 2012 204 126 A1 in the form of a steam generator, which is located in the exhaust line of a motor vehicle. In this case, the steam generator comprises a housing with inlet and outlet zones, and inside and coaxially to the housing there is a tubular flow line extending from the inlet zone to the outlet. This flow line also has slots at its end portions located in the inlet and outlet zones, so that the exhaust gas entering the steam generator can enter the space between the housing wall and the flow line. In this gap next to the flow line is a spiral tube through which liquid to be vaporized can flow. In this case, the helical tube, in one embodiment having disc-shaped fins to enhance heat transfer, serves as a structural element of the heat exchanger through which the heat energy contained in the exhaust gas is transferred to the evaporated liquid. In addition, a control valve is located inside the steam generator, more precisely inside the flow line, and, depending on the position of the control valve, the flow line is in a closed or open position. Preferably, the control valve is located in the inlet zone, and when the flow line is closed, the exhaust gas flows through the slots in the end region of the flow line into the gap between the flow line and the housing and flows into the spiral pipe. With an open flow line, the waste gas, bypassing the intermediate zone, immediately flows from the inlet zone to the outlet zone, due to the transfer of heat from the waste gas to the evaporated liquid is essentially prevented. In addition, in one embodiment DE 10 2012 204 126 A1, two steam generators mentioned above are described, which are spaced apart and substantially parallel to each other in order to achieve high evaporation efficiency, whereby the flow through the spiral tubes of both steam generators takes place exclusively in one direction and countercurrent to the flowing exhaust gas.

US 2011/0289905 A1 describes another generic device for heat recovery, which comprises a housing and a flow line located inside the housing and coaxially therewith, a shut-off valve is located inside the housing and also inside the flow line. By means of this check valve, the flow line can be closed so that the exhaust gas supplied to the inlet zone of the device passes through an opening located in the direction of flow of the waste gas upstream of the check valve into an intermediate region between the flow line and the housing. Inside the intermediate region, there are two non-communicating, but adjacent to each other, spiral pipes, coaxial with the flow line, which have different diameters and each contain an inlet and outlet for the heating medium. The individual pipes forming the spiral pipes have a rectangular cross-section and are spirally twisted around their longitudinal axis.

A device similar to the one in US 2011/0289905 A1 is described in US 2005/0133202 A1. However, unlike US 2011/0289905 A1, US 2005/0133202 A1 describes coaxial spiral pipes connected to each other via a common inlet as well as a common outlet and provided with rib structures, in one embodiment, in the interval between the flow line and the body can contain more than two such spiral tubes. Thus, the spiral pipes are connected to each other in a parallel configuration, so that the medium flow in the individual spiral pipes always flows in the same direction. To obtain radially spaced spiral pipes, they are inserted between the plates from the quarter of the cylinder separated by pins, which during manufacture separate the individual spiral pipes from each other during manufacture. However, after the heat treatment of the spiral tubes, these plates are removed, with the result that the spiral tubes remain separated from each other without aids.

For all of these solutions described in the prior art, the distance traveled by the exhaust gas through the device (hereinafter the flow length) essentially corresponds to the length of the device. This leads to the fact that heat transfer can only occur at this distance, which leads to a low efficiency of the device.

EP 1 460 363 A1 discloses a heat exchanger which has a central flow channel and a bypass channel consisting of at least two flow chambers connected to one another. In this case, one part of the pipeline system is located in both flow chambers of the bypass channel. In addition, the central flow channel also has a portion of said pipeline system.

A heat exchanger is also known from US 2010/0200080 A1, which has a central flow channel, which is surrounded by a bypass channel having two connected flow chambers. In these flow chambers, in turn, part of the spiral conduit is located. The heat exchanger has a switching valve located on the downstream side to close the central flow channel and to feed the waste gas into the bypass channel.

WO 2016/088489 A1 shows a heat exchanger which has only one bypass passage, which surrounds a central flow passage that is closed by a valve. In this case, a heat exchange element is located in the bypass channel.

WO 93/03318 A1 discloses a heat exchanger which has a central flow channel which has a plurality of edge flow channels arranged concentrically with respect to the central flow channel and connected to one another.

Against this background, it is an object of the invention to provide a device of the type mentioned above in such a way that the heat exchanger system of the device has an increased flow length as compared to the prior art, in order to provide an increase in efficiency.

This problem is solved by means of a device with the features of paragraph 1 of the claims. The dependent claims relate to particularly advantageous improvements to the invention.

Thus, according to the invention, there is provided a device for recovering heat from a heating medium, which comprises a heat exchanger system with a central flow channel surrounded by at least one edge flow channel. In this case, at least one heat exchange element is located inside the edge flow channel, by means of which, during operation of the waste heat source, heat from the heating medium created by the waste heat source can be transferred to the working medium flowing through the heat exchange element. In addition, the central flow channel as well as the edge flow channel each have at least one inlet for inflowing the heating medium. Further, according to the invention, the edge flow channel comprises at least two flow chambers dividing the edge flow channel perpendicular to the central axis of the heat exchanger system, thereby achieving the greatest possible length of flow through the edge flow channel. In this case, the flow chambers can run parallel to each other and also to the central flow channel, and / or, in particular, coaxially. As a result, the main flow direction of the heating medium is established within the flow chambers, which is oriented substantially parallel to the central axis of the heat exchanger system and thus parallel to the central flow channel. Sectioning or dividing the edge flow channel into separate parallel flow chambers, in particular located coaxially as well as perpendicular to the central axis of the heat exchanger system, can be achieved, for example, by the fact that between the flow chambers of the edge flow channel and between the central flow channel and the edge flow channel in the longitudinal direction of the flow chambers and the central flow channel are formed by extending parallel to each other dividing walls for separating the fluid. Since the flow chambers collectively form an edge flow channel, they must be hydraulically connected to each other in at least one section. An end-to-end termination of the flow chambers to prevent unwanted escape of the heating medium - with the exception of the external flow channel outlet - should be considered mandatory, with the flow chambers extending substantially along the entire length of the central flow channel.

In this connection, a fluid connection means a substance-permeable connection that can be permeable at least to fluids as well as gases. However, this does not exclude permeability to solids. It goes without saying that energy can also be transmitted via this hydraulic connection.

In an improved embodiment, the central flow channel can be configured as a cylindrical central tube, with the heat exchanger system being substantially rotationally symmetric. In this connection, it is possible for the peripheral flow channel surrounding the central flow channel and thus also the flow chambers of the edge flow channel to be formed by an intermediate space between the central tube and / or arranged coaxially around the central tube and cylindrically formed edge tubes of different diameters, the central the pipe and / or edge pipes form dividing walls for the separation of the fluid. In addition, the outermost, most distant from the central axis of the heat exchanger system, the edge flow channel can be particularly advantageously in a structurally elegant manner formed by an intermediate space between the edge tube and the substantially cylindrical body of the heat exchanger system.

The heating medium can be, in particular, an exhaust gas that flows through an exhaust duct, in particular an exhaust duct of an internal combustion engine. In this case, the internal combustion engine can be the waste heat source described above. Accordingly, the heating medium will flow through the heating medium path which corresponds to the exhaust path, in particular the exhaust path of an internal combustion engine, for example, an automobile internal combustion engine.

According to the invention, the central flow channel serves as a bypass for the marginal flow channel, and for this function the central flow channel must be designed to be partially or completely open or closed. This can be achieved, for example, by using a channel seal, by means of which the volumetric flow of the heating medium through the central flow channel and / or the edge flow channel can be influenced depending on the degree of opening of the channel seal.

The working medium must be a fluid that, due to the heat transferred to it by the heat exchange element from the heating medium, passes from the liquid phase to the gaseous phase, that is, it can evaporate. Suitable working media are, for example, water and alcohols such as ethanol. In addition, various types of refrigerants can be used as the working medium.

In one particularly preferred further development of the invention, the flow chambers are in series hydrodynamically connected to each other through end zones lying in the longitudinal direction of the flow chambers, so that heating medium can alternately flow through the flow chambers of the edge flow channel. This means that the heating medium flows through the flow chambers in series but not in parallel. This has the advantage, in addition to the directional main flow of the heating medium, that the heating medium travels a greater distance when flowing through the edge flow channel than in the case of parallel flow. Increasing the distance traveled allows more heat to be successfully transferred from the heating medium. The hydrodynamic connection between the individual flow chambers can be made through overflow holes, which must be formed alternately at opposite ends of the flow chambers so that successive flow through the flow chambers is achieved with the greatest possible length of flow through the edge flow channel.

Further, one extremely advantageous embodiment of the invention is based on the fact that a heat exchange element or a partial component of a heat exchange element is located in each flow chamber of the edge flow channel. Thus, it is possible, firstly, that in one or several flow chambers there are separately made heat exchange elements, and secondly, that the heat exchange element consists of at least two hydrodynamically connected partial components through which the working medium can flow, and in this case, each flow chamber contains one partial component. In addition, it is possible to have a mixed configuration, in which a heat exchange element is located in one or more flow chambers, and one partial component is located in the other flow chambers. With such a configuration, it is possible to transfer heat from the heating medium to different circuits of the working medium in an advantageous manner, whereby, as a result of the targeted placement of the heat exchange elements and / or partial components of the heat exchange elements, a different temperature rise of the working medium in the working medium circuit can be realized. However, the configuration of the heat exchange element with at least two partial components is preferred, with one partial component being located in each flow chamber.

If, in addition, during the operation of the heat exchanger system, the direction of flow of the heating medium through each flow chamber is opposite to the direction of flow of the working medium through the heat exchange element or partial component of the heat exchange element located in the corresponding flow chamber, it can be considered advantageous that the working medium and the heating medium in As a result, they flow through the heat exchanger system inside the edge flow channel always in opposite directions, i.e. the heat exchanger system always works on the counterflow principle. With a suitable choice of the point of inflow of the working medium into the heat exchange element, as well as the heating medium into the edge flow channel, it is possible, due to the opposite direction of flow of the working medium and the heating medium along the flow length of the edge flow channel, to advantageously achieve the maximum possible temperature difference between the working medium and the heating medium and thereby increasing the efficiency of the heat exchanger system.

An embodiment of the invention should also be considered highly promising, in which the heat exchange element is made as a coiled conduit from a helically passing pipe, and / or a coiled conduit from a helically passing pipe, contains at least two layers located coaxially to each other, and the layers of the coiled conduit will correspond partial components of the heat exchange element. Such a coiled conduit represents a very economical design of the heat exchange element and, in addition, provides, compared with possible embodiments with several straight individual pipes running substantially parallel to each other and parallel to the central and edge flow channels, the advantage that uneven distribution of the volumetric flow of the heating medium. In the case of several individual pipes, it can happen that such uneven distribution will lead to local overheating and / or overcooling of different individual pipes, which may result in non-uniform evaporation or even lack of evaporation of the working medium and / or the occurrence of a defect in the locally overheated individual pipes. A further embodiment with a coiled tubing, in which ribs are formed on its outer side surface, enhances the heat flux from the heating medium to the working medium, whereby the heat transfer efficiency can be improved. In this case, it is permissible that the ribs are formed by the fact that an endless tape spirally wrapped in the longitudinal direction of the pipe is applied to the pipe carrying at least in some sections of the rib, cut to size in accordance with the length of the section. The connection between the endless strip forming the rib and the pipe can be made with a material closure, and the creation of a material closure can be realized using a welding process, in particular, laser welding.

One particularly preferred improvement of the invention is also characterized in that each layer of the coiled conduit is respectively arranged in one of the flow chambers of the edge flow channel, which results in an optimal design of the heat exchanger system with respect to the design of the edge flow channel with a heat exchange element located in the edge flow channel, for example, relatively use of installation space, efficiency (efficiency), as well as from an economic point of view.

If, in one embodiment of the device, the central flow channel is closed at its opposite end from the inlet of the central flow channel, then the heat exchanger system in this respect must be designed so that it can be used, for example, for long-term operation at low load and associated low temperatures ... As a result, the function of the central flow channel in the form of an opening or closing bypass for the edge flow channel, if necessary, depending on the load, is not ensured, which reduces the design and production and technical costs, as well as the associated production costs.

In addition, in one highly practical embodiment of the invention, the inlet of the edge flow channel is formed in the central flow channel, with an even number of flow chambers, the inlet of the edge flow channel is formed in an end region of the central flow channel opposite from the inlet of the central flow channel, and with an odd number of flow chambers in the end zone of the central flow channel facing the inlet of the central flow channel. In this case, in principle, the edge flow channel should be connected to the central flow channel exclusively via the inlet of the edge flow channel. This is true regardless of whether the central flow channel can be opened for through flow or closed on one side. If the edge flow channel is configured, for example with two or four flow chambers, the inlet of the edge flow channel would be formed at the end of the central flow channel opposite from the inlet of the central flow channel. If, on the other hand, three or five flow chambers are formed in the edge flow channel, the inlet of the edge flow channel will be formed at the end of the central flow channel facing the inlet of the central flow channel.

Further, very promising should be considered an improved version of the invention, in which the coiled conduit has a fluid inlet as well as a fluid outlet, the fluid inlet being formed in the innermost layer of the coiled conduit, and the fluid outlet in the outermost layer of the coiled tubing. pipeline. In this case, the innermost row of the coiled pipeline is at the smallest, and the outermost layer of the coiled pipeline is at the greatest distance, measured perpendicular to the central axis, with a rotationally symmetric design, the layer of the coiled pipeline is radially spaced from the central flow channel. An advantage of a coiled tubing constructed in this manner is that it enables the continuous operation of the heat exchanger system according to the counterflow principle, whereby an increase in the efficiency of the heat exchanger system can be advantageously achieved, which is beneficial.

If, in addition, the device is characterized in that it has a channel seal downstream of the outlet of the central flow channel and / or the outlet of the edge flow channel, by means of which the volumetric flow of the heating medium can be regulated, i.e., controlled and / or set. the central flow channel and / or the edge flow channel, it is possible to change the height of the volumetric flow of the heating medium through the central flow channel and / or the edge flow channel, while at the same time the design of the heat exchanger system will have less susceptibility to malfunctions during operation. The channel valve is designed according to the invention as an exhaust gas valve, the angular position of which can be changed by the camshaft. Due to the placement downstream of the central flow channel and / or the edge flow channel, and thus according to the invention outside the heat exchanger system, it is possible to use flue gas dampers with a shorter camshaft than when placed inside the heat exchanger system. This makes it possible to reduce the likelihood of malfunctions, for example due to a jammed camshaft and / or due to the design of the channel valve, made in the form of an exhaust gas damper.

The invention allows for a large number of embodiments. To better clarify its basic principle, one of these options is shown in the drawing and will be described below.

The figure shows an improved version of the heat exchanger system 1, and the central flow channel 3, forming part of the heat exchanger system 1, is surrounded by an edge flow channel 2. Inside the edge flow channel 2 there is a heat exchange element 4, made as a coiled conduit 13, which, when the waste heat source operates for transferring heat from the heating medium created by the waste heat source into the working medium flowing through the heat exchange element 4. The edge flow channel 2 is divided perpendicularly to the central axis 7 of the heat exchanger system 1 into two flow chambers 8, and the flow chambers 8 are separated from each other by parallel separation walls 21 for separating flowing media. In addition, the flow chambers 8 are sequentially hydrodynamically connected to each other by end zones located in the longitudinal direction 9 of the flow chambers 8, 22, so that during operation of the heat exchanger system 1, in accordance with the function of the external flow channel, the heating medium can sequentially flow through the flow chambers 8. In this case, in each flow chamber 8 there is a partial component 10 of the heat exchange element 4 made in the form of a layer 14 of the coiled conduit, and the layers 14 of the coiled conduit, in turn, are arranged coaxially with respect to each other. In this case, the coiled conduit 13 has a fluid inlet 17 and a fluid outlet 18, wherein the fluid inlet 17 is formed in the innermost layer 14 of the coiled conduit, and the fluid outlet 18 in the outermost of the layers 14 of the coiled conduit 13 . The heating medium entering during operation of the heat exchanger system 1 through the inlet 6 of the central flow channel 3 into the heat exchanger system 1 overflows through the inlet 5 formed in the central flow channel 3 into the outer edge flow channel 2. Since in this case there are two, that is, an even number flow chambers 8, inlet 5 is formed in the end zone 15 of the central flow channel 3 opposite to the inlet 6 of the central flow channel 3. To allow the heating medium to pass from the central flow channel 3 to the edge flow channel 2, the central flow channel 3 is also closed at the end in the opposite direction. from the inlet 6 of the central flow channel 3 to the end zone 15. In this case, setting the direction of flow 11 of the heating medium, which is oriented essentially in the longitudinal direction 9 of the flow chambers 8 and thus parallel to the central flow channel 3. After flowing through the innermost flow chamber 8, i.e. through the flow chamber 8, which has the smallest distance, counted perpendicular to the central axis 7, from the central flow channel 3, the heating medium flows into the outermost flow chamber 8, which for this purpose are hydraulically connected to each other through the overflow opening 20. Moreover, in this improved version, the overflow opening 20 is formed parallel to the end zone 16 of the central flow channel 3. The outermost of the flow chambers 8 has correspondingly the greatest distance, counted perpendicular to the central axis 7, from the central flow channel 3. After flowing through the outermost flow chamber 8, the heating medium leaves the edge flow channel 2 through its outlet 19. The direction of flow 12 of the working medium, which is installed in the twisted pipeline made in the form of layers 14 of the partial component 10 of the heat exchange element 4, made as a twisted pipeline 13, is opposite to the direction of flow 11 of the heating medium through the corresponding flow chamber 8, in which the corresponding partial component 10. The direction of flow 11 of the heating medium through the flow chambers 8 is also opposite in successive flow chambers 8. This also applies to the direction of flow 12 of the working medium through successive partial components 10.

List of positions

1 Heat exchanger system 2 Edge flow channel 3 central flow channel 4 heat exchange element five inlet 6 inlet 7 central axis eight flow chamber nine longitudinal direction ten partial component eleven heating medium flow direction 12 working fluid flow direction 13 twisted pipeline fourteen coiled tubing layers fifteen end zone sixteen end zone 17 fluid inlet 18 fluid outlet nineteen edge flow channel outlet 20 bypass hole 21 fluid dividing wall 22 end zone

Claims (9)

1. A device for recovering heat from an exhaust gas flowing through the exhaust tract of an internal combustion engine, which contains a heat exchanger system (1) with a central flow channel (3) surrounded by at least one edge flow channel (2), and inside the edge flow channel ( 2) at least one heat exchange element (4) is located, by means of which, during the operation of the said internal combustion engine, the heat from the exhaust gas generated by the specified internal combustion engine can be transferred to the working medium flowing through the heat exchange element (4), and the central flow channel (3) , as well as the edge flow channel (2) each have at least one inlet (5, 6) for inflow of exhaust gas, and the edge flow channel (2) has at least two flow chambers (8) dividing the edge flow channel (2) perpendicular to the central axis (7) of the heat exchanger system (1), and the device downstream of the central outlet The flow channel (3) and / or the outlet (19) of the edge flow channel (2) has a channel closure by means of which the volumetric flow of the waste gas through the central flow channel (3) and / or the edge flow channel (2) can be controlled, characterized in that that the central flow channel (3) serves as a bypass for the edge flow channel (2), and said channel shutter is made in the form of an exhaust gas damper, the angular position of which can be changed by means of the camshaft, and this waste gas damper is located outside the system ( 1) heat exchanger. 2. A device according to claim 1, characterized in that the flow chambers (8) are connected in series with each other in the end zones (22) located in the longitudinal direction (9) of the flow chambers (8), so that the waste gas can flow in series through the flow chambers (8) of the edge flow channel (2). 3. A device according to claim 1 or 2, characterized in that a heat exchange element (4) or a partial component (10) of a heat exchange element (4) is located in each flow chamber (8). 4. The device according to one of the previous paragraphs, characterized in that during operation of the heat exchanger system (1), the direction (11) of the flow of the exhaust gas through each flow chamber (8) is opposite to the direction (12) of the flow of the working medium through located in the corresponding flow chamber (8) ) a heat exchange element (4) or a disposed partial component (10) of a heat exchange element (4). 5. A device according to one of the preceding claims, characterized in that the heat exchange element (4) is made as a coiled conduit (13) from a spiral pipe, and / or a coiled pipe (13) formed from a spiral pipe contains at least two coaxial to each other layer (14) of the coiled pipeline. 6. The device according to one of the previous paragraphs, characterized in that in each of the flow chambers (8) of the edge flow channel (2) is located on one of the layers (14) of the coiled pipeline (13). 7. A device according to one of the previous claims, characterized in that the central flow channel (3) in its edge zone (15) facing away from the inlet (6) of the central flow channel (3) is closed at the end. 8. The device according to one of the previous paragraphs, characterized in that the inlet (5) of the edge flow channel (2) is formed in the central flow channel (3), and with an even number of flow chambers (8), the inlet (5) of the edge flow channel (2) ) is formed in the end zone (15) of the central flow channel (3) facing away from the inlet (6) of the central flow channel (3), and with an odd number of flow chambers (8) - in the end zone (16) of the central flow channel (3) facing the inlet (6) of the central flow channel (3). 9. Device according to one of the preceding claims, characterized in that the coiled conduit (13) comprises a fluid inlet (17) and a fluid outlet (18), the fluid inlet (17) being formed in the innermost layer (14) coiled tubing, and the outlet (18) for the fluid is in the outermost layer (14) of the coiled tubing (13).

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