EP3635315A1

EP3635315A1 - Apparatus for heat recovery

Info

Publication number: EP3635315A1
Application number: EP18728067.2A
Authority: EP
Inventors: Jens Gockel; Hilmar LÄMMER; Christian Urban
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2017-06-08
Filing date: 2018-05-22
Publication date: 2020-04-15
Also published as: WO2018224296A1; DE102017209728A1; RU2735768C1

Abstract

The invention relates to an apparatus for the recovery of heat from a heating fluid, comprising a heat transfer arrangement (1) having at least one core flow channel (3) surrounded by at least one outer flow channel (2), wherein at least one heat transfer element (4) is arranged within the outer flow channel (2), by means of which heat transfer element, during operation of a waste heat source, heat from a heating fluid generated by the waste heat source can be transferred into a working fluid flowing through the heat transfer element (4), and the core flow channel (3) and the outer flow channel (2) each have at least one inlet (5, 6) for admitting the heating fluid. Furthermore, the outer flow channel (2) has at least two flow chambers (8) dividing the outer flow channel (2) orthogonally relative to a central axis (7) of the heat transfer arrangement (1).

Description

description

Device for heat recovery

The invention relates to a device for heat recovery from a heating fluid, which has a heat exchanger arrangement with a core flow channel surrounded by at least one edge flow channel. In this case, at least one heat transfer element is arranged within the edge flow channel, by means of which during operation of a

Waste heat source heat from a heat fluid generated by the waste heat source in a heat transfer element flowing through the working fluid is transferable. Of the

Core flow channel and the edge flow channel also each have at least one inlet for the inflow of the heating fluid.

A device of the type mentioned is described by DE 10 2012 204 126 A1 in the form of a steam generator, which is arranged in the exhaust tract of a motor vehicle engine. The steam generator in this case has a housing with an inlet and an outlet region, wherein inside and coaxial with the housing extending from the inlet to the outlet region, tubular feedthrough line is arranged. This feedthrough line is also slotted at its lying in the inlet and outlet end portions, so that the flowing into the steam generator exhaust gas in a space between

Housing wall and feedthrough line can get. In this space adjacent to the feedthrough line a spiral tube is arranged, which is flowed through by a fluid to be evaporated. The spiral tube in one embodiment to increase the heat transfer disk-like ribs having spiral tube serves as a heat transfer device through which the existing thermal energy in the exhaust gas is transferred to the fluid to be evaporated. Furthermore, a control valve is arranged within the steam generator, in the exact inside of the feedthrough line, by means of which, depending on the position of the control flap, the feedthrough line is present in a closed or opened state. Preferably, the control flap is arranged in the inlet region, wherein the exhaust gas passes through the slotted end region of the feedthrough line in the intermediate space between the feedthrough line and the housing and flows over the spiral tube when the feedthrough line is closed. If the feedthrough line is in the open state, the exhaust gas, bypassing the intermediate region, passes directly from the inlet to the outlet region, as a result of which heat transfer from the exhaust gas into the fluid to be evaporated is largely reduced. An embodiment of DE 10 2012 204 126 A1 describes In addition, two of the aforementioned steam generator, which are spaced and arranged substantially parallel to each other in order to achieve a high evaporation performance, wherein the flow through the spiral tubes of the steam generator takes place only in one direction and in countercurrent to the flowing exhaust gas.

The US 201 1/0289905 A1 describes another, generic device for

Heat recovery, which has a housing and a disposed within the housing and coaxial therewith feedthrough line, wherein inside the housing and in this case within the feedthrough line also a blocking flap is arranged. By means of this blocking flap, the feedthrough line can be closed, so that one in one

Inlet portion of the device passed exhaust gas passes through an opening located in the flow direction of the exhaust gas in front of the blocking flap in an intermediate region between feedthrough line and housing. Within the intermediate region, two spiral tubes which are not connected to each other but abutting one another are arranged coaxially to the feed-through line, which have diameters differing from each other and each have an inlet and a drain for a fluid to be heated. The individual tubes forming the spiral tubes in this case have a rectangular cross-section and are around their

Longitudinal axis twisted spirally.

A comparable with the US 201 1/0289905 A1 device shows the US 2005/0133202 A1. However, in contrast to US 201 1/0289905 A1, US 2005/0133202 A1 describes mutually co-axially arranged spiral tubes connected to one another via a common inlet and a common outlet and provided with rib structures. In one embodiment, more than two of these spiral tubes are arranged in the space between

Feedthrough line and housing can be arranged. The respective spiral tubes are thus interconnected in a parallel arrangement, so that the flow of the fluid in the individual spiral tubes always runs rectified. To produce the spirally spaced spiral tubes they are separated by rods

Quarter-cylinder plates introduced, which separate the individual spiral tubes in the preparation of each other. However, these are removed again after a heat treatment of the spiral tubes, whereby the spiral tubes are free-standing separated from each other.

All solutions described in the prior art have a flow-through length of the exhaust gas through the devices, which corresponds substantially to the length of the devices. This results in that a transfer of heat can only take place over this distance, which leads to a low efficiency of the devices. Against this background, the invention has the object, the device of the type mentioned in such a way that the heat exchanger assembly of the device has an increased compared to the prior art flow length to a

To increase the efficiency.

This object is achieved with a device according to the features of claim 1. The subclaims relate to particularly expedient developments of the invention.

According to the invention, therefore, a device for heat recovery from a heating fluid is provided, which has a heat exchanger arrangement with one of at least one

Having edge flow channel surrounded core flow channel. In this case, at least one heat exchanger element is arranged within the edge flow channel, by means of which heat can be transferred from a heat fluid generated by the waste heat source into a heat transfer element flowing through the working fluid during operation of a waste heat source. Of the

Core flow channel and the edge flow channel also each have at least one inlet for the inflow of the heating fluid. Furthermore, according to the invention, the edge flow channel has at least two flow chambers subdividing the edge flow channel orthogonal to a central axis of the heat exchanger arrangement, thereby achieving the highest possible flow length through the edge flow channel. The

Flow chambers may in this case run parallel to one another and / or in particular coaxially to one another and to the core flow channel. This would be within the

Flow chambers set a main flow direction of the heating fluid, which in

Aligned substantially parallel to the central axis of the heat exchanger assembly and thus parallel to the core flow channel. The subdivision or separation of the

Randströmungskanals in single, parallel and in this case in particular coaxially extending and arranged orthogonal to the central axis of the heat exchanger assembly flow chambers can be achieved, for example, that between the

Flow chambers of the edge flow channel and between the core flow channel and edge flow channel in the longitudinal direction of the flow chambers and the core flow channel are formed parallel to each other fluid partition walls. Due to the fact that the entirety of the flow chambers form the edge flow channel, they would consequently have to be connected in a fluid-permeable manner in at least one section. A frontal completion of the flow chambers to avoid an undesirable exit of the heating fluid is, except for an outlet of the edge flow channel, as mandatory to view, wherein the flow chambers extend substantially over the same length of the core flow channel.

The fluid-permeable compound in this context means a permeable compound, which is permeable at least for fluids and gases. However, permeability to solids is not excluded. It is also to be taken for granted that energy can also be transmitted via this fluid-permeable connection.

According to the invention, the core flow channel can be formed by a cylindrically shaped core tube, wherein the heat exchanger arrangement would be formed essentially rotationally symmetrical per se. In this context, it is conceivable that the edge flow channel surrounding the core flow channel and thus also the

Flow chambers of the edge flow channel through spaces between the core tube and / or around the core tube coaxially arranged and cylindrically shaped edge tubes of different diameters are pronounced and this core tubes and / or edge tubes form the fluid separation walls. An outermost, from the central axis of the heat exchanger assembly farthest edge flow channel could also be particularly advantageously designed in a structurally skilled manner by a gap between an edge tube and a substantially cylindrically shaped housing of the heat exchanger assembly.

The heating fluid may in particular be designed as an exhaust gas, which flows through an exhaust gas tract, in particular an exhaust gas tract of an internal combustion engine. The internal combustion engine could represent the described waste heat source. The heating fluid could flow through a Heizfluidtrakt corresponding to the exhaust tract, in particular the exhaust gas tract of the internal combustion engine, such as. B. an internal combustion engine of a motor vehicle, corresponds.

It is conceivable that the core flow channel serves as a bypass for the edge flow channel, wherein the core flow channel for such a function would have to be partially or completely closed or obviously executed. This could be, for example, by a

Achieve channel closure element, by means of which the volume flow of the heating fluid through the core flow channel and / or the edge flow channel in dependence of

Opening rate of the channel closure element could be influenced. The working fluid should be formed as a fluid, which passes through the transferred from the heating fluid through the heat transfer element heat from the liquid to the gaseous phase, so it can be evaporated. Are eligible for such a working fluid

for example, water, but also alcohols such as ethanol. In addition, it was possible to use different types of refrigerant as the working fluid.

In a particularly advantageous development of the invention, the flow chambers are fluid-permeably connected in series to one another in frontal regions lying in the longitudinal direction of the flow chambers, so that the flow chambers of the edge flow channel can be flowed through sequentially by the heating fluid. This means that the flow chambers are flowed through in succession and not in a parallel manner by the heating fluid. In addition to a directed main flow of the heating fluid, this offers the advantage that, compared to a parallel flow, a larger flow-through length of the edge flow channel through which the heating fluid flows is effected. With the increase in the flow-through length, it is advantageously possible that a higher amount of heat can be transferred from the heating fluid. The fluid-permeable connection between the individual flow chambers can be effected by overflow openings, which in each case alternately to the

should be formed opposite ends of the flow chambers, so that a successive flow through the flow chambers is achieved with the highest possible flow length of the edge flow channel.

An additionally extremely profitable embodiment of the invention is based on the fact that a heat exchanger element or a partial component of the heat exchanger element is arranged in each of the flow chambers of the edge flow channel. Thus, it is conceivable that on the one hand in one or more of the flow chambers separately formed heat transfer elements are arranged, and on the other hand that a

Heat transfer element consists of at least two fluid-permeable connected sub-components, which are flowed through by the working fluid and in this case each one of

Subcomponents are each arranged in a flow chamber. In addition, there is the possibility that a mixing arrangement is present, so that in one or more

Flow chambers, a heat transfer element is arranged, while in further

Flow chambers each subcomponents are arranged. On the basis of such an embodiment, it would be advantageous to transfer heat from the heating fluid into different working fluid circuits, whereby a different temperature increase of the working fluid in the working fluid circuits could be realized by targeted arrangement of the heat transfer elements and / or subcomponents of the heat transfer elements. However, one is preferred Arrangement of a heat transfer element with at least two sub-components, wherein each one of the sub-components is arranged in each case a flow chamber.

Further, in the operation of the heat exchanger assembly, the flow direction of the heating fluid through each of the flow chambers of the flow direction of the working fluid through the arranged in the respective flow chamber heat transfer element or arranged subcomponent of the heat transfer element, this may be considered to be advantageous in that thereby working fluid and heating fluid

Heat exchanger arrangement within the edge flow channel always in opposite directions

to flow through, d. H. the heat exchanger assembly always works in countercurrent principle. With a suitable choice of the inflow point of working fluid in the heat transfer element and the heating fluid in the edge flow channel could be due to the opposite flow of working fluid and heating fluid over the flow length of the

Randströmungskanals profitably the largest possible temperature difference between working fluid and heating fluid and thus an increase in the efficiency of

Achieve heat exchanger arrangement.

In addition, an extremely promising embodiment of the invention is provided when the heat exchanger element is formed as a coiled tubing from a spirally extending tube and / or formed from the spirally extending pipe coiled tubing at least two coaxially arranged coiled tubing layers, wherein the coiled tubing layers the subcomponents of the heat transfer element can correspond. In this case, such a coiled tubing represents a very cost-effective embodiment of the heat transfer element and also offers a possible

Variant with several straight and substantially parallel to each other and parallel to the core and edge flow channel extending individual tubes the advantage that adjusts no unequal distribution of the flow rate of the heating fluid. In the case of several individual tubes, it is possible that such an unequal distribution leads to local overheating and / or hypothermia of different individual tubes, which can result in uneven or even non-existent evaporation of the working fluid and / or a defect in the locally overheated individual tubes. An additional embodiment of the coiled tubing

to the effect that ribs are formed on the outer circumferential surface, increases the heat flow from the heating fluid into the working fluid, whereby the efficiency of the

Heat transfer can be increased. It is conceivable that the ribs are formed by the fact that on the ribs at least partially supporting tube an in the longitudinal direction of the tube spirally umwindendes endless belt is applied, which Section length is cut to length accordingly. The connection between the ribs forming the endless belt and the tube may be cohesively formed, wherein the

Production of the material bond using a welding process, in particular a laser welding process, can be done.

A particularly advantageous embodiment of the invention is also characterized in that a respective one of the tube helical layers of the coiled tubing is arranged in each case one of the flow chambers of the edge flow channel, whereby an optimal structure of the

Heat exchanger arrangement with respect to the configuration of the edge flow channel with arranged in the edge flow channel heat transfer element z. B. in terms

Space utilization, efficiency and economic aspects results.

If, in an embodiment of the device, the core flow channel is closed at its front end facing away from the inlet of the core flow channel, then this would be

Heat exchanger arrangement designed to the effect that this z. For example, for applications with low load and associated low temperatures in a permanent

Heat exchanger operation would work. A function of the core flow channel as an optionally load dependent opening or closing bypass for the

Randströmungskanal would not be given, which reduces the design and manufacturing costs and the associated production costs.

In a further highly practical embodiment of the invention, the inlet of the edge flow channel is formed in the core flow channel, wherein the inlet of the edge flow channel with an even number of flow chambers in the end of the core flow channel facing away from the inlet of the core flow channel, with an odd number of flow chambers, is formed facing the inlet of the core flow channel end region of the core flow channel. In principle, the edge flow channel should be connected exclusively to the core flow channel via the inlet of the edge flow channel. This applies regardless of whether the

Core flow channel is flow permeable apparent or closed on one side. In embodiment of the edge flow channel with, for example, two or four

Flow chambers would be a formation of the inlet of the edge flow channel at the end of the core flow channel facing away from the end of the core flow channel. If, however, three or five flow chambers in the edge flow channel is configured, the formation of the inlet of the edge flow channel at the inlet of the

Core flow channel facing the end of the core flow channel shown. A further development of the invention is also very promising when the tube coil has a fluid inlet and a fluid outlet, wherein the fluid inlet is formed in an innermost of the tube coil layers, the fluid outlet in an outermost of the tube coil layers of the tube coil. Here, the innermost of the tube coil layers is the least, the outermost of the tube coil layers furthest in the orthogonal direction to the

Central axis, in rotationally symmetrical design in the radial direction of the

Kernströmungskanals spaced tube coil layer of the coiled tubing. The configured in this way coiled tubing has the advantage that a constant work of

Heat exchanger arrangement in countercurrent principle can be made possible, thereby profitably an increase in the efficiency of the heat exchanger assembly can be achieved.

If the device is further characterized in that it has downstream of an outlet of the core flow channel and / or an outlet of the edge flow channel a channel closure element, by means of which a volume flow of the heating fluid through the core flow channel and / or the edge flow channel adjustable, that is controllable and / or regulated, then could the height of the volume flow of the heating fluid through the

Core flow channel and / or the edge flow channel can be varied, at the same time the structure of the heat exchanger assembly would have a low susceptibility to errors. The channel closure element could be designed, for example, as an exhaust flap whose angular position is variable via a control shaft. Due to the arrangement downstream of the core flow channel and / or edge flow channel and thus outside the

Heat exchanger arrangement would allow the use of an exhaust valve with a comparison with an arrangement within the heat exchanger arrangement shorter control shaft. This would allow the probability of a fault due to, for example, a

Jamming the control shaft and / or designed as an exhaust flap

Reduce the channel closure element.

The invention allows numerous embodiments. To further clarify its basic principle, one of them is shown in the drawing and will be described below.

This shows in the figure, a development of the heat exchanger assembly 1, wherein the part of the heat exchanger assembly 1 forming core flow channel 3 of the

Edge flow channel 2 is surrounded. Within the boundary flow channel 2, the heat exchanger element 4 designed as a coiled tube 13 is arranged, which during operation of a Waste heat source serves to transfer heat from a heat fluid generated by the waste heat source in a working fluid flowing through the heat transfer element 4. Of the

Edge flow channel 2 is in this case orthogonal to the central axis 7 of the

Heat exchanger assembly 1 divided into two flow chambers 8, wherein the

Flow chambers 8 are separated from each other by the parallel fluid partition walls 21. The flow chambers 8 are also connected fluid-permeable to each other at the lying in the longitudinal direction 9 of the flow chambers 8 end portion 22, whereby the flow chambers 8 are sequentially flows through during operation of the heat exchanger assembly 1 of the function of the edge flow channel 2 of the heating fluid sequentially. In each of the flow chambers 8 is formed as a tube coil layer 14 sub-component 10 of the tube coil 13 formed as

Heat exchanger element 4 is arranged, wherein the tube coil layers 14 are in turn arranged coaxially to each other. In this case, the coiled tubing 13 has a fluid inlet 17 and a fluid outlet 18, the fluid inlet 17 being formed in the innermost of the tube coil layers 14, the fluid outlet 18 being formed in the outermost one of the tube coil layers 14 of the tube coil 13. The heating fluid, which flows into the heat exchanger arrangement 1 via the inlet 6 of the core flow channel 3 during operation of the heat exchanger arrangement 1, is heated by the heating fluid

Kernströmungskanal 3 formed inlet 5 in the edge of the flow channel 2. The inlet 5 is in this case due to the two formed and thus an even number of flow chambers 8 in the inlet 6 of the core flow channel 3 facing away from

End region 15 of the core flow channel 3 is formed. In order to allow the transfer of the heating fluid from the core flow channel 3 into the edge flow channel 2, the

Core flow channel 3 also at the inlet 6 of the core flow channel third

facing away end 15 closed at the front. It turns this one

Flow direction 1 1 of the heating fluid, which is located substantially in the longitudinal direction 9 of the flow chambers 8 and is thus aligned parallel to the core flow channel 3. After flowing through the innermost flow chamber 8, ie that flow chamber 8 which orthogonal to the central axis 7 has the smallest distance to the core flow channel 3, the heating fluid passes into the outermost of the flow chambers 8, which are fluidly connected to each other through the overflow opening 20 for this purpose. The overflow opening 20 is also formed parallel to the end region 16 of the core flow channel 3 in this development. The outermost of the flow chambers 8 has

corresponding to orthogonal to the central axis 7 on the largest distance to the core flow channel 3. After flowing through the outermost flow chamber 8, the heating fluid exits the edge flow channel 2 via its outlet 19. The formed in the tube coil layers 14 formed as part components 10 of the tube coil 13 as Heat transfer element 4 each adjusting flow direction 12 of the working fluid is in each case the flow direction 1 1 of the heating fluid through the respective flow chamber 8, in which the respective sub-component 10 is arranged, directed in opposite directions. The

Flow direction 1 1 of the heating fluid through the flow chambers 8 is in the

successive flow chambers 8 also opposite to each other. This behavior is similar in the direction of flow 12 of the working fluid through the respective successive subcomponents 10.

LIST OF REFERENCE NUMBERS

1 heat exchanger arrangement

2 edge flow channel

3 core flow channel

4 heat exchanger element

5 inlet

6 inlet

7 central axis

8 flow chamber

9 longitudinal direction

10 subcomponent

1 1 flow direction heating fluid

12 flow direction working fluid

13 coiled tubing

14 tube coil layers

15 end area

16 end area

17 fluid inlet

18 fluid outlet

19 outlet edge duct

20 overflow opening

21 fluid partition wall

22 forehead area

Claims

claims

1. A device for heat recovery from a heating fluid, comprising a

Heat exchanger arrangement (1) with one of at least one edge flow channel (2) surrounded core flow channel (3), wherein within the edge flow channel (2) at least one heat transfer element (4) is arranged, by means of which during operation of a waste heat source heat from a heat generated by the waste heat source in a working fluid flowing through the heat exchanger element (4) can be transferred and the core flow channel (3) and the edge flow channel (2) each have at least one inlet (5, 6) for flowing in the heating fluid, characterized in that the edge flow channel (2) at least two the edge flow channel (2) orthogonal to a central axis (7) of the heat exchanger assembly (1) dividing flow chambers (8).

2. Apparatus according to claim 1, characterized in that the flow chambers (8) in the longitudinal direction (9) of the flow chambers (8) lying end portions (22) are fluidly connected in series with each other, so that the flow chambers (8) of the edge flow channel (2). can be flowed through sequentially from the heating fluid.

3. Device according to claims 1 or 2, characterized in that in each of the flow chambers (8) a heat transfer element (4) or a subcomponent (10) of the heat transfer element (4) is arranged.

4. Device according to at least one of the preceding claims, characterized

characterized in that during operation of the heat exchanger arrangement (1) the

Flow direction (1 1) of the heating fluid through each of the flow chambers (8) of the flow direction (12) of the working fluid through the arranged in the respective flow chamber (8) heat transfer element (4) or arranged subcomponent (10) of the heat transfer element (4) is directed opposite.

5. Device according to at least one of the preceding claims, characterized

in that the heat exchanger element (4) is designed as a tube coil (13) made of a spiral tube and / or that of the spiral Having tubular tube formed extending pipe (13) has at least two mutually coaxially arranged tube coil layers (14).

6. Device according to at least one of the preceding claims, characterized

in that a respective one of the tube spiral layers (14) of the tube helix (13) is arranged in each case in one of the flow chambers (8) of the edge flow channel (2).

7. Device according to at least one of the preceding claims, characterized

characterized in that the core flow channel (3) at its the inlet (6) of the

Core flow channel (3) facing away from end region (15) is closed at the end.

8. Device according to at least one of the preceding claims, characterized

characterized in that the inlet (5) of the edge flow channel (2) in the

Core inlet channel (3) is formed, wherein the inlet (5) of the edge flow channel (2) in an even number of flow chambers (8) in the inlet (6) of the core flow channel (3) facing away from the end region (15) of the core flow channel (3), with an odd number of flow chambers (8) that the inlet (6) of the

Core flow channel (3) facing the end region (16) of the core flow channel (3) is formed.

9. Device according to at least one of the preceding claims, characterized

in that the coiled tube (13) has a fluid inlet (17) and a

Fluid outlet (18), wherein the fluid inlet (17) in an innermost of the

Pipe helical layers (14), the fluid outlet (18) in an outermost of the tube helical layers (14) of the tube helix (13) is formed.

10. Device according to at least one of the preceding claims, characterized

characterized in that the device is downstream of an outlet of the

Core flow channel (3) and / or an outlet (19) of the edge flow channel (2) has a channel closure element, by means of which a volume flow of the heating fluid through the core flow channel (3) and / or the edge flow channel (2) is adjustable.