WO2013041315A1

WO2013041315A1 - Heat transfer arrangement

Info

Publication number: WO2013041315A1
Application number: PCT/EP2012/066058
Authority: WO
Inventors: Bernd Burkhardt
Original assignee: Friedrich Boysen Gmbh & Co. Kg
Priority date: 2011-09-20
Filing date: 2012-08-17
Publication date: 2013-03-28
Also published as: BR112014006444A2; US20150053382A1; DE102011113788A1; CN103782124B; CN103782124A

Abstract

A heat transfer arrangement for heating a working fluid by means of a flowing hot fluid comprises a fluid channel for carrying the flowing hot fluid, a pipe bundle arranged in the fluid channel for carrying the working fluid, wherein the pipe bundle comprises a number of pipeline segments running parallel to each other in a longitudinal direction and a carrying structure permanently connected to the fluid channel for holding the pipe bundle in the fluid channel. The pipeline segments are each supported on the carrying structure on at least a first non-moving bearing point and on at least a second bearing point separated from the first bearing point in the longitudinal direction and having clearance movement in at least one direction.

Description

Heat transfer assembly

The present invention relates to a heat transfer arrangement for heating, in particular evaporation and superheating, a working fluid by means of a flowing hot fluid, in particular an exhaust gas stream of an internal combustion engine, having a fluid channel for guiding the flowing hot fluid, a tube bundle arranged in the fluid channel for guiding the working fluid the tube bundle comprises a plurality of pipe sections running parallel to one another along a longitudinal direction, and a support structure fixedly connected to the fluid channel for holding the tube bundle in the fluid channel. Such devices are also referred to as "heat exchangers" and find use in various ways of utilizing waste heat carried by the hot fluid. For example, such heat exchangers can be used for exhaust heat utilization in internal combustion engines by a part of the thermal energy of the hot exhaust gas stream is converted into technically usable mechanical energy, for example in the context of a closed steam cycle. As a result, ultimately fuel can be saved. The parallel, in particular straight pipe sections of the tube bundle are flowed around by the hot fluid, wherein an effective heat transfer takes place on the working fluid located in the interior of the tube sections. The tube bundle can in principle be arranged at any point in an exhaust pipe, for example in a silencer housing. The attachment of the tube bundle in the fluid channel is problematic insofar as during operation always thermal expansions and mechanical stresses occur, which can lead to a critical material load in the pipe sections.

It is therefore an object of the invention to enable with simple structural means a secure attachment of heat exchangers in tube bundle design on the associated fluid channel. The object is achieved by a heat transfer arrangement with the features of claim 1.

According to the invention, the pipe sections are each mounted immovably on at least one first bearing point on the support structure and mounted on at least one longitudinally spaced therefrom second bearing with freedom of movement in at least one direction on the support structure. The tube bundle is thus mounted at least twice, wherein a bearing is designed as a fixed bearing and at least one of them remote bearing as a floating bearing. Thus, on the one hand a secure attachment of the pipe sections with each other and the tube bundle within the fluid channel is ensured. On the other hand, the floating bearing allows compensating movements of the pipe sections due to thermal expansion or mechanical stresses, so that undesirable stresses or material overloads are avoided.

Further developments of the invention are specified in the dependent claims, the description and the accompanying drawings. According to one embodiment of the invention, the movement margin at the second bearing point, preferably exclusively, in the longitudinal direction. Thus, the thermal expansions and contractions of the pipe sections, which frequently occur during operation, can be compensated in the axial direction.

According to a further embodiment of the invention, all the first and / or all second bearing points lie in a respective transverse plane extending at right angles to the longitudinal direction. All pipe sections of the tube bundle are thus supported evenly in two places.

The support structure may comprise a first support element for providing all first bearing points and a second support element separate from the first support element for providing all second bearing points. This makes it possible to provide a free space between the two separate support elements, which accommodates a substantially unimpeded flow through the tube bundle.

Preferably, the support elements are formed flat and each extending in a direction perpendicular to the longitudinal direction extending

Transverse plane. In a flow of the tube bundle transverse to the longitudinal direction of the hot fluid flow thus only a small resistance is opposed. Preferably, the support structure comprises at least one, preferably two, arrangements of stacked elongated spacers which are each arranged transversely to the longitudinal direction and in which recesses are provided for passing adjacent pipe sections. The spacers can be between individual levels of the Tube bundle be arranged and thus stabilize the bundle and hold.

According to a preferred embodiment of the invention, means for clamping the stacked spacers against each other are provided. By bracing the spacers against each other is a fixation of all pipe sections of the tube bundle, wherein it is left to the dimensioning of the recesses, whether in the clamped state, a range of motion for the pipe sections, that is, whether a fixed bearing or a floating bearing is made.

To clamp the stacked spacers, two clamping straps arranged above and below the tube bundle and enclosing the arrangement of spacers can be provided. This allows a particularly simple construction.

The clamping bracket can be moved towards each other by means of a screw, in particular by means of an arrangement of threaded rods and nuts. By tightening the nuts, the clamps can thus be moved towards each other, wherein the spacers located between the clamps compressed and the tube bundle is fixed. An arrangement of threaded rods and associated nuts minimizes in particular the production cost of the tension. According to one embodiment of the invention, the clamping bracket in the tensioned state by means of a rigid bridging element connected to each other, in particular welded together. In this embodiment, the screw connection can be omitted. The spacers may also be fixed relative to each other by at least one U-shaped rail. Such a rail can prevent unwanted slippage of the spacers before or during the bracing.

According to a further embodiment of the invention, flow guide walls are arranged in the fluid channel on both sides of the tube bundle. Such Strömungsleitwände can improve the efficiency of the heat exchanger by passing the hot fluid flow selectively between the individual pipe sections. Preferably, the flow baffles may be provided with beads to further reduce the lateral flow of hot fluid past the tube bundle.

The invention also relates to a heat engine with a heat transfer arrangement according to one of the preceding embodiments, an expansion machine and a condenser for cooling the working fluid, wherein the working fluid in a cyclic process, in particular in a Rankine Rank cycle, by the heat transfer assembly, the expansion machine and the capacitor is guided. The heat transfer arrangement can thus work, as it were, both as an evaporator and as a superheater, wherein the working fluid is heated, evaporated and superheated with the aid of the thermal energy of the hot fluid. The thermal energy thus stored in the working fluid is converted into technically usable mechanical energy in the expansion machine. Subsequently, the working fluid is recondensed in the condenser, cooled back and finally fed again to the heat transfer arrangement. Furthermore, the invention relates to an exhaust system for an internal combustion engine, in which a heat transfer assembly is integrated as described above.

The invention will now be described by way of example with reference to the drawings.

Fig. 1 shows a perspective view of a heat transfer assembly according to a first embodiment of the invention.

Fig. 2 shows a heat transfer assembly according to a second embodiment of the invention. Fig. 3 shows a heat transfer assembly according to a third embodiment of the invention.

According to FIG. 1, a heat exchanger comprises a tube bundle 11, which in the present exemplary embodiment comprises 24 tube coils 12 arranged side by side and fed individually with a working fluid. Each coil 12 comprises a plurality of stacked and parallel rectilinear duct sections 13, each extending parallel to a longitudinal direction L and connected by inclined U-shaped arches 14. The tube bundle 1 1 is designed for mounting in a fluid channel, not shown, for example in a silencer housing an exhaust line. The hot exhaust gas flows along one

Main flow direction S through the fluid channel and applies to the arrangement of pipe sections 13. This results in an effective heat transfer from the hot exhaust gas to that in the coils 12 guided working fluid. The working fluid can be vaporized and overheated in this way, so that it can subsequently perform mechanical work in an expansion machine. Subsequently, the working fluid is condensed, cooled back and fed back to the tube bundle 1 1.

The attachment of the tube bundle 1 1 in the fluid channel by means of a support structure 15, which comprises two separate retaining rings 15 a, 15 b. The retaining rings 15a, 15b are formed flat and each extending in a direction perpendicular to the longitudinal direction L extending transverse plane. In this way, the flow of the exhaust gas along the main flow direction S is only minimally hindered. The outer periphery of the retaining rings 15a, 15b is formed for fixed connection to the fluid channel and adapted specifically to the geometry of the channel wall. An adaptation of the support structure 15 to different types of fluid idan channels can thus be done by a simple replacement of the retaining rings 15 a, 15 b.

At each of the retaining rings 15a, 15b flat opposite two clamping brackets 23 are welded. Before welding, the tensioning brackets 23 can be moved towards each other by means of two threaded rods 25 and associated nuts 37. Between the two clamping brackets 23 is in each case an array of stacked elongated spacer strips 19, which are each passed between the horizontal planes of the tube bundle 1 1 and in which recesses 21 are provided for performing the adjacent pipe sections 13. U-shaped profiled rails 29 respectively surround the threaded rods 25 and thus ensure a correct alignment of the spacer strips 19 relative to each other. By tightening the nuts 27, the spacer strips 19 can be braced against one another, wherein the tube guide sections 13 are clamped in the recesses 21. Each pipe section 13 is thus received at a first bearing 17a and at a second bearing 17b spaced apart in the longitudinal direction L thereof in corresponding recesses 21 of the spacer strips 19 and held relative to the support structure 15. In this case, the extent of the pinching of the pipe sections 13 in the recesses is selected so that each pipe section 13 is immovably held on the first bearing 17 a, whereas at the second bearing 17 b a certain range of motion in the axial direction, that is in the longitudinal direction L. All the first bearing points 17a lie in the transverse plane defined by the retaining ring 15a on the left, while all second bearing points 17b lie in the transverse plane defined by the right-hand retaining ring 15b. When the support structure 15 is fastened in a fluid channel, secure storage of the tube bundle 11 at two spaced locations is thus ensured, while at the same time axial compensation movements of the tube sections 13 are always possible.

2, a further embodiment of a heat exchanger according to the invention is shown, which is constructed in principle as the arrangement of FIG. In addition, however, 1 1 Strömungsleitwände 30 are provided on both sides of the tube bundle to better pass through the hot exhaust gas stream through the tube bundle 1 1. Corrugations 31 provided in the flow guide walls 30 each protrude into the interstices between adjacent tube coils 12 and thus reduce undesirable lateral flow of the exhaust gas past the side.

Fig. 3 shows a further embodiment of a heat exchanger according to the invention, in which case instead of the screw threaded end 25 and nuts 27 formed the U-shaped rails 29th even with the clamps 23 and optionally welded to the spacer strips 19. The respective arrangement of clamping brackets 23, spacer strips 19 and rails 29 is biased for this purpose in a suitable clamping device and welded in a clamped state. The connection of the rails 29 with the spacer strips 19 can be made selectively or over the entire surface.

It is understood that the principle of dual storage with movement possibility for a variety of different types of Strömungsfüh- tion is applicable, and it does not matter in particular whether the individual straight pipe sections 13 are connected in parallel, serially or in a combined manner.

LIST OF REFERENCE NUMBERS

11 tube bundles

12 pipe coil

13 pipe section

14 sheets

15 supporting structure

15a, 15b retaining ring

17a first depository

17b second depository

19 spacer bar

21 recess

23 clamping bracket

25 threaded rod

27 mother

29 rail

30 flow guide wall

31 beading

L longitudinal direction

S main flow direction

Claims

claims

1. heat transfer arrangement for heating, in particular evaporation and superheating, a working fluid by means of a flowing hot fluid, in particular an exhaust gas stream of an internal combustion engine, with

a fluid channel for guiding the flowing hot fluid, a tube bundle (11) arranged in the fluid channel for guiding the working fluid, the tube bundle comprising a plurality of tube sections (13) running parallel to each other along a longitudinal direction (L), and

a support structure (15) fixedly connected to the fluid channel for holding the tube bundle (11) in the fluid channel,

By doing so, that is

the pipe sections (13) are mounted immovably on at least one first bearing point (17a) on the support structure (15) and on at least one second bearing point (17b) spaced therefrom in the longitudinal direction (L) with freedom of movement in at least one direction on the support structure (15 ) are stored.

2. Heat transfer arrangement according to claim 1,

By doing so, that is

the movement margin at the second bearing point (17b), preferably exclusively, in the longitudinal direction (L) consists.

3. Heat transfer arrangement according to claim 1 or 2,

characterized in that all first and / or all second bearing points (17a, 17b) lie in a respective transverse plane perpendicular to the longitudinal direction (L).

Heat transfer arrangement according to at least one of the preceding claims,

By doing so, that is

the support structure (15) comprises a first support element (15a) for providing all first bearing points (17a) and a second support element (15b) separate from the first support element (15a) for providing all second bearing points (17b).

Heat transfer arrangement according to claim 4,

By doing so, that is

the support elements (15a, 15b) are formed flat and each extending in a direction perpendicular to the longitudinal direction (L) extending transverse plane.

Heat transfer arrangement according to at least one of the preceding claims,

By doing so, that is

the support structure (15) comprises at least one, preferably two, arrays of stacked elongate spacers (19) each disposed transverse to the longitudinal direction (L) and in which are provided recesses (21) for passing adjacent pipe sections (13).

Heat transfer arrangement according to claim 6,

characterized in that Means (23, 25, 27, 29) for clamping the stacked spacers (19) against each other are provided.

8. Heat transfer arrangement according to claim 7,

By doing so, that is

for clamping the stacked spacers (19) two above and below the tube bundle (11) arranged, the arrangement of spacers (19) enclosing clamping bracket (23) are provided.

Heat transfer arrangement according to claim 8,

By doing so, that is

the clamping bracket (23) by means of a screw (25, 27) are movable towards each other, in particular by means of an arrangement of threaded rods (25) and nuts (27).

Heat transfer arrangement according to claim 8 or 9,

By doing so, that is

the clamping bracket (23) in the tensioned state by means of a rigid bridging element (29) connected to each other, in particular welded together, are.

Heat transfer arrangement according to at least one of claims 6 to 10,

By doing so, that is

the spacers (19) are fixed relative to one another by at least one U-shaped profiled rail (29).

12. Heat transfer arrangement according to at least one of the preceding claims, characterized in that

on both sides of the tube bundle (11) flow guide walls (30) in the

Fluid channel are arranged.

Heat engine, comprising a heat transfer arrangement according to one of the preceding claims, an expansion machine and a condenser for cooling the working fluid, wherein the working fluid in a cyclic process, in particular in a Clius- Rankine cycle, passed through the heat transfer assembly, the expansion machine and the condenser becomes.

Exhaust system for an internal combustion engine, in which a heat transfer arrangement according to one of claims 1 to 12 is integrated.