DE102017209728A1 - Device for heat recovery - Google Patents

Abstract

The invention relates to 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 In the operation of a waste heat source heat from a heating fluid generated by the waste heat source in a heat transfer element (4) flowing through the working fluid is transferable and the core flow channel (3) and the Randströmungskanal (2) each have at least one inlet (5, 6) for flowing the Heizfluides. Furthermore, the edge flow channel (2) has at least two flow chambers (8) subdividing the edge flow channel (2) orthogonal to a central axis (7) of the heat exchanger arrangement (1).

Description

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 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. 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 by the 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 coaxially to 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 can pass into a space between the housing wall and feedthrough line. 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. A variant of the DE 10 2012 204 126 A1 also describes two of the aforementioned steam generators, which are spaced and arranged substantially parallel to each other to achieve a high evaporation performance, wherein the flow through the spiral tubes of both steam generators takes place exclusively in one direction and in countercurrent to the flowing exhaust gas.

The US 2011/0289905 A1 describes another, generic device for heat recovery, which has a housing and a disposed within the housing and coaxially thereto 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 an exhaust gas conducted into an inlet region of the device passes through an opening in the flow direction of the exhaust gas upstream of the blocking flap into 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 spirally twisted about their longitudinal axis.

One with the US 2011/0289905 A1 comparable device shows the US 2005/0133202 A1 , In contrast to US 2011/0289905 A1 describes the US 2005/0133202 A1 However, co-axially with each other via a common inlet and a common outlet connected and provided with rib structures arranged spiral tubes, wherein in one embodiment, more than two of these spiral tubes can be arranged in the space between feedthrough line and housing. 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 introduced between bars separated by quarter-cylinder plates, 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 to perform 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 achieve an increase in 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 a core flow channel surrounded by at least one edge 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. 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 can in this case run parallel to one another and / or in particular coaxially to one another and also to the core flow channel. This would set a main flow direction of the heating fluid within the flow chambers, which is aligned substantially parallel to the central axis of the heat exchanger assembly and thus parallel to the core flow channel. The subdivision or else separation of the edge flow channel into individual flow chambers arranged parallel to one another and orthogonal to the center axis of the heat exchanger arrangement can be achieved, for example, in parallel 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 mutually extending fluid separating walls are formed. 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. An end-side termination of the flow chambers to avoid an undesired exit of the heating fluid, except for an outlet of the edge flow channel, to be regarded as obligatory, 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 are formed by intermediate spaces between the core tube and / or around the core tube coaxially arranged and cylindrically shaped edge tubes of different diameters and this core tubes and / or edge tubes the fluid partitions form. 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 made partially or completely closable or openable. This could be achieved, for example, by means of a channel closure element, by means of which the volumetric flow of the heating fluid through the core flow channel and / or the edge flow channel could be influenced as a function of an opening rate of the channel closure element.

The working fluid should be formed as a fluid which passes from the liquid to the gaseous phase by the heat transferred from the heating fluid through the heat transfer element, so it can be evaporated. For such a working fluid such as water, but also alcohols such as ethanol come into question. 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 should each be formed alternately at the 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 exchanger elements are arranged, and on the other hand, that a heat transfer element consists of at least two fluid-permeable connected subcomponents, which are flowed through by the working fluid and in each case one of the sub-components in each case Flow chamber is arranged. 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 in each case sub-components 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, an arrangement of a heat exchanger element with at least two subcomponents is preferred, wherein one of the subcomponents is in each case arranged in a respective 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 disposed 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 always flow in opposite directions within the edge flow channel, d. H. the heat exchanger assembly always works in countercurrent principle. With a suitable choice of Einströmungspunktes 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 greatest possible temperature spread between the working fluid and heating fluid and thus achieve an increase in the efficiency of the heat exchanger assembly.

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 is a very cost-effective design of the heat transfer element and also offers over a possible embodiment 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 volume flow 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 heat transfer efficiency can be increased. It is conceivable that the ribs are formed by the fact that on the ribs at least partially supporting tube a spiral in the longitudinal direction of the tube umwindendes endless belt is applied, which is cut to length of the section accordingly. The connection between the endless belt forming the ribs and the pipe can be formed cohesively, wherein the production of the material bond can be carried out using a welding process, in particular a laser welding process.

A particularly advantageous development of the invention is also characterized in that a respective one of the tube helical turns of the coiled tubing is arranged in each of the flow chambers of the edge flow channel, whereby an optimal structure of the heat exchanger arrangement with respect to the design of the edge flow channel with arranged in the edge flow channel heat transfer element z. B. in terms of space utilization, efficiency and economic considerations.

If, in one 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 the heat exchanger arrangement would be designed such that it can be designed, for B. would work for applications with low load and associated low temperatures in a permanent heat transfer operation. A function of the core flow channel as an optionally load-dependent opening or closing bypass for the edge flow channel would not be given, which reduces the design and manufacturing costs and the associated manufacturing 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 is true regardless of whether the core flow channel is openable or openable flow permeable. When configuring the edge flow channel with, for example, two or even four flow chambers, formation of the inlet of the edge flow channel would be provided at the end of the core flow channel facing away from the inlet of the core flow channel. If, on the other hand, three or five flow chambers are configured in the edge flow channel, the formation of the inlet of the edge flow channel is shown at the end of the core flow channel facing the inlet of the core flow channel.

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 helical layers, the fluid outlet is formed in an outermost of the tube helical layers of the tube helix. 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, with rotationally symmetrical design in the radial direction of the core flow channel spaced tube coil layer of the coiled tubing. The coiled tubing configured in this manner has the advantage that a continuous operation of the heat exchanger arrangement in countercurrent principle can be made possible, whereby an increase in the efficiency of the heat exchanger arrangement can be achieved profitably.

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 the height of the volume flow of the heating fluid could be varied by the core flow channel and / or the edge flow channel, at the same time the construction of the heat exchanger arrangement would have a low susceptibility to failure. 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 of the heat exchanger arrangement, the use of an exhaust flap with a comparison with an arrangement within the heat exchanger arrangement shorter control shaft is made possible. This would reduce the likelihood of a fault due to, for example, jamming of the control shaft and / or the duct closure element designed as an exhaust flap.

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 one part of the heat exchanger arrangement 1 forming core flow channel 3 from the edge flow channel 2 is surrounded. Within the edge flow channel 2 is this as a coiled tubing 13 trained heat transfer element 4 arranged, which serves in the operation of a waste heat source, heat from a heating fluid generated by the waste heat source in a heat transfer element 4 to transfer flowing working fluid. The edge flow channel 2 itself is orthogonal to the central axis 7 the heat exchanger assembly 1 in two flow chambers 8th divided, with the flow chambers 8th through the mutually parallel fluid partition walls 21 are separated from each other. The flow chambers 8th are also on the longitudinal direction 9 the flow chambers 8th lying forehead area 22 connected fluidly to each other in series, whereby the flow chambers 8th during operation of the heat exchanger arrangement 1 the function of the edge flow channel 2 be sequentially flowed through by the heating fluid. In each of the flow chambers 8th is one as a tube coil layer 14 trained subcomponent 10 as a coiled tube 13 trained heat transfer element 4 arranged, wherein the tube coil layers 14 are again arranged coaxially with each other. The coiled tubing 13 has a fluid inlet 17 and a fluid outlet 18 on, with the fluid inlet 17 in the innermost of the tube coil layers 14 , the fluid outlet 18 in the outermost of the tube coil layers 14 the coiled tubing 13 is trained. This during operation of the heat exchanger arrangement 1 over the inlet 6 of the core flow channel 3 in the heat exchanger arrangement 1 inflowing heating fluid is through the in the core flow channel 3 trained inlet 5 in the edge flow channel 2 reconciled. The inlet 5 This is due to the two trained and thus an even number of flow chambers 8th in the inlet 6 of the core flow channel 3 opposite end region 15 of the core flow channel 3 educated. To the transfer of the heating fluid from the core flow channel 3 in the edge flow channel 2 to allow, is the core flow channel 3 also at the inlet 6 of the core flow channel 3 opposite end region 15 closed at the front. It turns this a flow direction 11 of the heating fluid which is substantially longitudinal 9 the flow chambers 8th is located and thus parallel to the core flow channel 3 is aligned. After flowing through the innermost flow chamber 8th that is, the flow chamber 8th which are orthogonal to the central axis 7 the smallest distance to the core flow channel 3 has, the heating fluid enters the outermost of the flow chambers 8th over, which for this purpose with each other through the overflow 20 fluid permeable connected. The overflow opening 20 is also in this development parallel to the end 16 of the core flow channel 3 educated. The outermost of the flow chambers 8th has corresponding orthogonal to the central axis 7 the largest distance to the core flow channel 3 on. After flowing through the outermost flow chamber 8th the heating fluid exits the edge flow channel 2 over its outlet 19 out. The in the as spiral tube layers 14 trained subcomponents 10 as a coiled tube 13 trained heat transfer element 4 each adjusting flow direction twelve of the working fluid is the direction of flow 11 of the heating fluid through the respective flow chamber 8th , in which the respective subcomponent 10 is arranged, opposite. The flow direction 11 of the heating fluid through the flow chambers 8th is at the successive flow chambers 8th also opposite each other. This is related to the flow direction twelve of the working fluid through the successive subcomponents 10 similar.

LIST OF REFERENCE NUMBERS

1

The heat exchanger

2

Edge flow channel

3

Core flow channel

4

heat transfer element

5

inlet

6

inlet

7

central axis

8th

flow chamber

9

longitudinal direction

10

subcomponent

11

Flow direction heating fluid

12

Flow direction of working fluid

13

coiled tubing

14

Coiled tubing documents

15

end

16

end

17

fluid inlet

18

fluid outlet

19

Outlet edge flow channel

20

overflow

21

fluid separation wall

22

forehead

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012204126 A1 [0002]
• US 2011/0289905 A1 [0003, 0004]
• US 2005/0133202 A1 [0004]

Claims (10)

Device for recovering heat from a heating fluid, comprising a heat exchanger arrangement (1) with a core flow channel (3) surrounded by at least one edge flow channel (2), wherein inside the edge flow channel (2) at least one heat transfer element (4) is arranged, by means of which during operation a waste heat source Heat from a heating fluid generated by the waste heat source in a the heat transfer element (4) flowing through the working fluid is transferable and the core flow channel (3) and the Randströmungskanal (2) each have at least one inlet (5, 6) for flowing the heating fluid, characterized in that the edge flow channel (2) has at least two flow chambers (8) subdividing the edge flow channel (2) orthogonal to a central axis (7) of the heat exchanger arrangement (1). Device after 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) are sequentially flowed through by the heating fluid , Device according to the 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. Device according to at least one of the preceding claims, characterized in that during operation of the heat exchanger arrangement (1) the flow direction (11) of the heating fluid through each of the flow chambers (8) of the flow direction (12) of the working fluid through that in the respective flow chamber (8) arranged Heat transfer element (4) or arranged sub-component (10) of the heat transfer element (4) is directed opposite. Device according to at least one of the preceding claims, characterized in that the heat transfer element (4) is designed as a coiled tubing (13) of a spirally extending tube and / or formed from the spirally extending tube coiled tubing (13) at least two coaxially arranged coiled tubing layers (14). Device according to at least one of the preceding claims, characterized in that a respective one of the tube helical layers (14) of the tube helix (13) is arranged in each case one of the flow chambers (8) of the edge flow channel (2). Device according to at least one of the preceding claims, characterized in that the core flow channel (3) at its the inlet (6) of the core flow channel (3) facing away from the end region (15) is closed at the end. Device according to at least one of the preceding claims, characterized in that the inlet (5) of the edge flow channel (2) is formed in the core flow channel (3), wherein the inlet (5) of the edge flow channel (2) is formed with an even number of flow chambers (8 in the end region (15) of the core flow channel (3) facing away from the inlet (6) of the core flow channel (3), with an odd number of flow chambers (8) facing the inlet (6) of the core flow channel (3) Core flow channel (3) is formed. 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 tube coil layers (14), the fluid outlet (18). in an outermost of the tube coil layers (14) of the tube coil (13) is formed. Device according to at least one of the preceding claims, characterized in that the device downstream of an outlet of the core flow channel (3) and / or an outlet (19) of the edge flow channel (2) comprises 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.

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