DE29601803U1 - Heat exchange device - Google Patents

Description

Heat exchange device

The present invention relates to a heat exchange device connected downstream of a heat source, which is reversibly expandable and compressible.

For the combustion of solid fuels such as coal, briquettes, coke, peat, lumpy wood, non-lumpy wood, straw or similar plant materials, numerous boiler systems such as through-burning boilers, under-burning boilers, fan-controlled under-burning boilers, underfeed firing systems, degassing firing systems and injection firing systems are known.

In the glowing zone of a first combustion chamber, the fuel is dried and carbonized (pyrolyzed) with the addition of primary air. The high-energy carbonization gas produced during carbonization is fed to a downstream afterburning chamber and burned there after mixing with possibly preheated, oxygen-rich secondary air.

Downstream of the afterburning chamber there is always a heat exchanger, which enables the energy contained in the flue gases to be transferred to the heating medium in the utilization circuit, for example to the ambient air or to the boiler flow (water).

It is known from the state of the art to use heat exchangers for this purpose, which consist of spiral-shaped copper or iron pipes, of individual plates or of ring-shaped cast parts, through which the heated flue gas flows on the inside and around which the heating medium of the utilization circuit flows on the outside, or vice versa.

The heat exchange surface of such a heat exchanger is designed to carry a precisely defined, average amount of heat.

If, for example, chopped wood is used as fuel, more than the average amount of energy is released during the peak of combustion. The amount of energy that exceeds the average amount of energy released cannot be absorbed by the heat exchangers known from the state of the art because they are designed to a certain average value. The amount of energy that exceeds the average amount of energy released is lost as heat, i.e. as so-called "flue gas loss", via the chimney.

As can be seen from Table 1 below, the amount of energy released during a combustion process or the temperature of the flue gas increases over time up to a certain value essentially 0 parallel to the amount of carbon dioxide released. After that, the carbon dioxide content remains unchanged at a

Plateau (CO _{2 max} ), while the temperature curve and, in connection with this, the exhaust gas loss fluctuates periodically depending on the energy released during the combustion process.

Table 1 Relationship between temperature and CO ₂ content during combustion of chopped wood

Furthermore, known heat exchangers used in manually fed combustion plants for solid fuels extract so little energy from the flue gases that their temperature when leaving the heat exchanger area is significantly above the dew point of water.

The energy obtained through the exothermic condensation of the moisture contained in the flue gases (dry wood has a water content of about 15% and a low hydrogen content; 2 H ₂ + O ₂ = 2 H ₂ O) is converted into

These heat exchangers are not used and are discharged to the heating medium. These heat exchangers only work in the calorific value range, but not in the always desirable calorific value range.
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To reduce pollutant emissions from combustion engines, catalysts are usually installed downstream, for example based on palladium or platinum, which are intended to ensure the most complete oxidation possible of the incompletely burned combustion products. The efficiency of such catalysts is highly temperature-dependent. The effectiveness of such catalysts only begins when a certain temperature of the catalyst material is exceeded.

Known spiral or plate-shaped heat exchangers, which protrude into the hot exhaust gas and serve to heat an air flow that passes through them and is intended to heat the interior of the vehicle, have the disadvantage that they extract heat energy from the exhaust gas during the start-up and warm-up phase of the engine.

As a result, the catalytic converter only reaches its operating temperature at a later point in time. The period in which exhaust gases laden with pollutants are released because the catalytic converter has not yet taken effect is considerably longer, particularly in the cold seasons. Given the large number of vehicles and the particularly pronounced environmental awareness today, this represents a particularly serious disadvantage.

The object of the present invention is therefore to provide a heat exchange device which is connected downstream of a heat source and is suitable for absorbing the excess energy provided essentially during the peak of heat generation to the extent that it exceeds the average amount of energy released during a proper heat generation process and for passing it on to the usage medium guided in the usage circuit in order to bring about the lowest possible loss of heat or exhaust gases and an improvement in efficiency and which makes it possible to supply the energy released by the exothermic condensation of the moisture contained in the smoke or exhaust gases to the usage medium in the usage circuit and thus to operate a combustion system for solid fuels in the so-called "calorific value range", and which, when installed in the exhaust system of an internal combustion engine, allows the primary heating of a downstream catalyst system by the combustion gases and only after its operating temperature has been reached, the heating of a usage medium, for example a directed air jet is permitted.

According to the invention, this object is achieved in a generic heat exchange device by the features specified in the characterizing part of patent claim 1. Particularly preferred embodiments are the subject of the subclaims.

Embodiments of the invention are described in more detail with reference to the drawings.

Show it:
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Figure 1 is a schematic, frontal view of a heat exchange device according to the invention with a vertically aligned, height-adjustable heat exchanger and a rigid-walled casing with a piston-shaped upper end,

Figure 2 is a schematic, frontal view of a heat exchange device according to the invention with a vertically aligned, height-adjustable heat exchanger and a height-adjustable casing with a closed top.

The most important feature of the heat exchange device according to the invention is that at least the length of the lateral legs of the U-shaped heat exchanger (1) and optionally also the length of the casing (10) are reversibly adjustable.

The surface area of the heat exchanger available for heat exchange can be reversibly selected so that only a precisely defined amount of energy is extracted from the medium (2) flowing inside the tubular heat exchanger (1). This "prevents excessive cooling of flue gases, for example, which would result in a downstream chimney

the formation of a negative pressure, i.e. a proper chimney draught, would not occur.

On the other hand, due to the length adjustability of the side legs of the U-shaped heat exchanger according to the invention, it is possible to set the medium {2) emerging from the interior of the heat exchanger (1) at the downstream end of the heat exchange device to a precisely definable temperature.

This provides the advantage that the combustion gas exiting the heat exchanger (1) can be cooled, for example, exactly to the dew point of the moisture contained in the combustion gas.

In this case, the energy released by the exothermic condensation of the moisture contained in the smoke or exhaust gases (2) can be fed to the usage medium (3) in the usage circuit (3) and thus, for the first time, a combustion system for solid fuels can be operated permanently in the so-called "calorific value range".

If a measuring probe (16) is provided in the area of the outlet (12) of the used medium (3), the temperature of the outgoing used medium (3) can be precisely set via the adjustable length of the side legs of the heat exchanger (1). This effect is particularly advantageous if the used medium (3) is used to heat a downstream drying or baking oven.

Since the combustion gases are only cooled down to the dew point and not further, the temperature of the escaping gases is still high enough to enable sufficient chimney draught by means of a small fan in a downstream chimney.

In addition, with the aid of the reversibly length-adjustable heat exchanger (1) according to the invention, the excess energy provided by the heat source (4) essentially during the peak of heat generation can be absorbed by the heat exchanger (1) adapted to this excess energy by means of the interaction of a measuring probe (16), a control element (17) and an adjustment device (8) and delivered to the usage medium (3) guided in the usage circuit to the extent that it exceeds the average amount of energy released during a proper heat generation process.

This leads to the advantage of extremely low heat or exhaust gas losses as well as an improvement in efficiency.

The following Table 2 shows the considerable energy savings that can be achieved with the heat exchange device according to the invention. While in conventional heat exchangers the amount of energy above the dashed line, which corresponds to the average energy released during a proper combustion process, is wasted by

the chimney, the heat exchange device according to the invention allows its unrestricted use.

Table 2 Relationship between temperature and CO ₂ content during combustion of chopped wood

A further advantage of the heat exchange device according to the invention is that when installed in the exhaust system of an internal combustion engine between the engine and the catalyst, with a "compressed", reduced heat exchanger (1) in the start-up or warm-up phase of the engine, the primary heating of a downstream catalyst system by the combustion gases is initially made possible.

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The control element (17) can be designed in such a way that it only sends a signal to the adjustment device (8) to "expand" the heat exchanger (1) and/or the casing (10) after the catalyst material has reached its operating temperature.

Only from this point onwards is energy extracted from the combustion gases to heat the medium used (3), for example an air jet directed into the interior of the vehicle or to the carburettor of the engine.

Of course, it is also possible to provide a heat exchange device according to the invention downstream of the catalyst. The length of the heat exchanger (1) to be set is determined in this case in particular by the desired temperature of the medium used (3) when it enters the vehicle interior or the carburetor area of the engine.

It is also noteworthy that the device according to the invention can be designed in the form of a radiator attached to a wall, whereby the depth of the radiator protruding into the room is controlled, for example, depending on the room temperature by an adjustment device (8) acting on a scissor-like mechanism. The most important advantage of such an expandable radiator is that it only takes up space during the heating process, but not in the warm seasons. This effect is particularly advantageous in small rooms.

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As can be seen from Figures 1 and 2, a heat exchange device according to the invention comprises at least one essentially tubular heat exchanger (1) for transferring the heat of a medium (2) flowing within the tubular heat exchanger (1) to a use medium flowing along the outside of the heat exchanger (1) in the same or opposite direction.

If a lower efficiency can be accepted, it is of course possible to let the hotter medium heated by the heat source (4) flow along the outside of the heat exchanger (1), while the medium to be heated flows preferably in the opposite direction inside the tubular heat exchanger.

The shape of the heat exchanger (1) according to the invention corresponds when viewed from the front essentially to the shape of a letter "U". When viewed from the side it is essentially aligned vertically upwards or downwards or horizontally. This even makes ceiling mounting possible, in which the heat exchanger (1) is expanded or compressed while hanging to the side or downwards.

The free end of one of the lateral U-legs, which is usually upstream, is connected to the heat source (4) when viewed from the front via a connection (14) that may be essentially horizontal. The free end of the opposite downstream

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The side U-leg is provided with a tubular connection (15) which may be essentially horizontally aligned for the forwarding of the medium (2) flowing within the tubular heat exchanger (1). The downstream end of this connection (15) can be connected, for example, to another heat exchanger (1) or to a chimney.

All walls (5,6) of at least the lateral U-legs of the heat exchanger (1) are designed so that the

The length of the two lateral U-legs and/or the size of the surface (5,6) around which the medium (2) flowing inside the tubular heat exchanger (1) flows in a substantially laminar manner is adjustable.
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In order to be able to adjust the length and/or the surface of at least the lateral U-legs of the heat exchanger to predetermined values, a mechanical, electrical, pneumatic or hydraulic adjustment device (8) acting directly or indirectly on the heat exchanger (1) is provided.

Furthermore, the heat exchange device according to the invention generally comprises at least one measuring probe (16) for determining at least one characteristic feature of the medium (2) flowing within the heat exchanger (1) and/or at least one measuring probe for determining at least one characteristic feature of the usage medium (3) flowing along the outside of the heat exchanger (1).

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The measuring probe (16) converts the determined value into a signal and supplies it wirelessly or wired to at least one control element (17), which is preferably programmable.

The control element (17) is therefore connected to each of the measuring probes (16) and receives from them the determined actual value of the respective characteristic feature. The control element (17) is designed in such a way that it compares the measured actual value with a setpoint value that can be set and stored via an input device, possibly in the form of a keyboard, and in the event of a deviation of the actual value from the stored setpoint value, it emits a control value signal to the adjustment device (8) that acts essentially vertically or horizontally and indirectly or directly at least on the heat exchanger (1).

This signal causes the adjustment device (8) to increase or decrease the length of the lateral U-legs and/or the surface area (5,6) of the heat exchanger (1) available for heat exchange.

Furthermore, the control element can be designed in such a way that it regulates the speed of a possibly present fan (19) in such a way that the combustion chamber (4) is supplied with at least a sufficient amount of air for optimal combustion.

0 The values measured by the measuring probe(s) (16) inside and/or outside the tubular heat exchanger (1)

Characteristic features can be identical or different in nature and can basically represent all measurable properties.

Preferably, the measuring probe (16) determines the temperature and/or the concentration of CO, CO ₂ , O ₂ , NO, aromatic hydrocarbons, soot, tar, waxes, resins, dust, condensate or other components of the medium (2) as a characteristic feature of the medium (2) flowing inside the tubular heat exchanger (1). The same or another measuring probe determines the temperature and/or the flow velocity and/or the viscosity as a characteristic feature of the use medium (3) flowing outside the tubular heat exchanger (1).

The heat source (4) upstream of the heat exchanger (1) according to the invention is a device whose primary or secondary purpose is to generate thermal energy. As a rule, it is a furnace or an internal combustion engine.

In the latter cases, the medium (2) flowing inside the tubular heat exchanger (1) is smoke or exhaust gas heated by a furnace (4), or exhaust gas heated by an internal combustion engine. The flow direction of this medium (2) is the same or opposite to the direction of the furnace (4) or the internal combustion engine.

In these cases, the medium (3) flowing along the outer walls of the tubular heat exchanger (1) is preferably air and/or water and/or steam and/or a natural or synthetic oil, the flow direction of the medium (3) being the same or opposite to the flow direction of the medium (2).

According to the invention, at least one measuring probe (16) for determining the temperature of the smoke or exhaust gas (2) flowing away from the combustion facility (4) or the internal combustion engine inside the tubular heat exchanger (1) is provided at the free end of the U-leg located downstream with respect to the flow direction of the smoke or exhaust gas (2) or in the region of the essentially horizontally aligned connection (15) adjoining it downstream for forwarding the smoke or exhaust gas (2).

The control element (17) is then designed in such a way that, upon receiving a signal transmitted by the measuring probe (16) which corresponds to a temperature which is above a certain threshold value preset via an input device (not shown), it sends an actuating signal to the adjustment device (8) which causes the adjustment device (8) to expand the U-shaped heat exchanger (1) at least partially in a vertical or horizontal direction in order to increase the surface area of the heat exchanger (1) available for heat exchange between the flue gas (2), which is then too hot, and the colder heat-dissipating medium (3).

The control element (17) is further designed in such a way that, upon receipt of a signal transmitted by the measuring probe (16) which corresponds to a temperature which is below a certain threshold value preset via an input device, it emits an actuating signal to the adjustment device (8) which causes the adjustment device (8) to lower or compress the U-shaped heat exchanger (1) at least partially in a vertical or horizontal direction in order to reduce the surface area of the heat exchanger (1) available for heat exchange between the flue gas (2) which is then too cold and the additional heat-dissipating usage medium (3).

Due to the fact that the heat exchanger (1) is maintained in a compressed state before a certain minimum exhaust gas temperature is reached, the temperature of the smoke or exhaust gas (2) flowing out of the downstream connection (15) reaches a high, preset value shortly after the combustion system (4) or the engine is started. This effect is particularly beneficial when temperature-dependent catalyst systems are used.

By the subsequent proportional adjustment of the surface of the heat exchanger (1) available for heat exchange to the temperature profile of the combustion, the temperature of the smoke or exhaust gas (2) flowing out of the downstream end of the connection (15) is kept essentially constant at a certain, preset value such as the dew point.

This results in an effective transfer of energy to the external, heat-dissipating medium (3) and thus in a reduction in heat and exhaust gas losses.

These measures allow combustion materials with different calorific or heating values to be used and to achieve optimized energy yield.

They also enable the combustion of solid fuels with different moisture contents and piece sizes even in the calorific value range, i.e. by utilising the condensation heat released during the condensation of the moisture contained in the smoke or exhaust gases.

The heat exchanger (1) according to the invention does not necessarily require a casing (10) for receiving and guiding the heat-dissipating medium (3).

In particular, if the ambient air is considered as the heat-dissipating medium (3), as is the case when the heat exchanger (1) according to the invention is used as a radiator or in a tiled stove, a casing (10) of the heat exchanger (1) can be dispensed with.

On the other hand, the formation of a casing is particularly advisable when the heat-dissipating medium (3) is water, steam, oil or air which is fed to a location that is different from the installation location of the

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to a location away from the combustion device.

The optionally provided casing (10) at least partially encloses the tubular heat exchanger (1), which essentially corresponds to the shape of a letter "U", and is essentially adapted to the U-shape of the heat exchanger (1).
As a rule, it also at least partially encloses the space (13) between the lateral U-legs of the heat exchanger (1).

"The casing (10) is at least somewhat and at least partially spaced from the walls of the heat exchanger (1) for the purpose of receiving and guiding the medium (3) flowing along the outside of the heat exchanger (1).

The walls of this casing (10) enclosing the lateral U-legs of the heat exchanger (1) are rigid in the longitudinal direction of the U-shaped heat exchanger (1) or are designed to be expandable and/or compressible in accordance with the orientation and type of the walls (5,6) of the heat exchanger (1).

Preferably, the adjustment device (8) controlled by the control element (17) not only acts on the heat exchanger (1) which is flexible in its longitudinal direction, but also indirectly or directly in the same direction and to the same extent on the casing (10).

In particular, in the case of the use of a gaseous heat-dissipating medium (3), for example air or steam, all walls of the casing (10) can be designed to be rigid and not displaceable against one another.

However, if liquid usage media (3) are used, it is recommended that, in the case of rigid side walls of the casing (10), at least the wall (20) of the casing (10) running parallel to the section of the heat exchanger (1) connecting the two side U-legs of the heat exchanger (1) should be designed essentially in the shape of a piston or in the form of a flexible film, which is sealingly connected to the edge region of the rigid side walls of the casing (10) and comes into contact with the surface of the heat-dissipating usage medium (3).

A casing (10) with a substantially piston-shaped wall (20) is shown in Figure 1.

If the piston-shaped wall (20) floats on the heat-dissipating medium (3), it is sufficient if the adjustment device (8), as shown in Figure 1, only acts on the heat exchanger (1) itself. Otherwise, it is advantageous if the adjustment device (8) only acts on the wall (20) and at least one, for example, rod-shaped device is provided between the wall (20) and the adjustable part of the heat exchanger (1) in order to transfer the movements of the wall (20) to the adjustable part of the heat exchanger (1).

Alternatively or in addition to the piston- or film-shaped design of the wall (20), the two side walls of the casing (10) can also be equipped with a mechanism for volume compensation, which allows compression and expansion of the casing (10) essentially in the same direction and to the same extent as the enclosed heat exchanger (1). An expandable and compressible casing is shown, for example, in Figure 2.

In principle, the same mechanisms that are suitable for the side walls of the U-shaped heat exchanger (1) are suitable as mechanisms for adjusting the side walls of the casing (10).

As can be seen from Figure 2, for example, at least one essentially rod-shaped spacer (21) is provided between the section of the heat exchanger (1) connecting the lateral legs of the U-shaped heat exchanger (1) and the wall of the casing (10) running parallel thereto. It is used in particular to transmit the movement exerted on the casing (10) by means of the adjustment device (8) to the movable part of the heat exchanger (1).

In the case of an adjustable casing (10), the adjustment device (8) preferably acts in that area of the casing (10) which, when viewed from the front, is essentially parallel to the two lateral vision

cle of the U-shaped heat exchanger (1) connecting the section of the heat exchanger (1).

In the area of the upstream and downstream two ends of the casing (10) there is provided either an opening (11) for the supply or an opening (12) for the removal of the external medium (3).

Preferably, the casing (10) encompasses the entire U-shaped heat exchanger (1) including at least a part of the intermediate space (13) and at least parts of the connection (14) running horizontally to the heat source (4) and the downstream connection (15). The heat-dissipating medium (3) flows around the enclosed parts essentially on all sides.

In particular for cleaning purposes, the U-shaped heat exchanger (1) and/or the two connections (14, 15) and/or the casing (10) can each have one or more essentially tightly sealable cleaning openings. These can in principle be located at any point on the respective component. However, they are preferably provided as an extension of the longitudinal axis of the two lateral legs of the U-shaped heat exchanger (1).

To reduce heat loss, the casing (10) can have insulation on the outside. In principle, all materials with a heat-insulating effect are suitable for forming the insulation layer.

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When viewed from the front, at least one essentially rectangular guide (18) adjustable in length is provided in the space (13) between the lateral U-legs of the heat exchanger (1) for guiding the medium (3) along the surfaces of the U-legs of the heat exchanger (1). When viewed from the side, its longitudinal axis is aligned parallel to the longitudinal axis of the U-shaped heat exchanger (1). When viewed from the front, the guide (18) extends parallel and essentially centrally to the U-legs of the heat exchanger (1). Its rear and front longitudinal sides are connected to the rear and front of the casing (10) in an essentially sealing and rigid manner or at least partially displaceable in the longitudinal direction of the guide (18). The end of the guide (18) pointing in the direction of the middle straight or curved section of the U-shaped heat exchanger (1) is at least somewhat spaced from this in order to ensure a substantially unhindered flow of the medium used (3). The opposite end of the guide (18) is connected to the casing (10) in a substantially sealing manner.

At least the walls (5, 6) of the lateral legs of the U-shaped heat exchanger (1) and/or the walls of the casing (10) enclosing the lateral legs of the U-shaped heat exchanger (1) can, in order to bring about the mentioned compressibility and expandability, at least partially have a bellows-like structure (7) which allows displacement along the longitudinal

* ** * ·■■·■

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axis of the side legs of the U-shaped heat exchanger (1), whereby the bellows (7) are dimensioned and mounted in such a way that they do not significantly reduce the flow cross-sections. 5

Alternatively or in addition to a bellows-like structure, they can have a roller shutter-like structure with a winding device that is optionally mounted and covered in a way that is advantageous from a flow point of view.

Alternatively or in addition to the possibilities already shown, the mechanism for adjusting the walls can essentially comprise plate-shaped elements which can be displaced relative to one another in the direction of the longitudinal axis of the lateral legs of the U-shaped heat exchanger (1) and are essentially connected to one another in a sealing manner.

The walls (5, 6) of the heat exchanger (1) are at least partially provided with elements for increasing the heat exchange surface, which protrude at least slightly into the medium (2) flowing away from the heat source (4) inside the tubular heat exchanger (1) and/or into the medium (3) flowing along the outside of the heat exchanger (1). These elements are preferably rib-, rod-, strip- or wave-shaped and are offset from one another in such a way that they do not hinder or even damage one another during a compression process. It is particularly important that both their shape and their location are selected in such a way that

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should be such that the media (2,3) flow around them in an essentially laminar manner.

It is also possible to provide flow resistances within the tubular heat exchanger (1) and/or the essentially horizontal connections (14, 15) of the heat exchanger (1) in such a way that the core flow, which is heated up the most by the heat source (4), has a narrow jet and is usually centered in the middle of the pipe, is fanned out and guided directly along the walls of the heat exchanger (1) and/or the horizontal connections (14, 15). Inserts whose cross-section consists of concentric rings that are at least slightly spaced apart from one another or is spiral-shaped have proven particularly useful as such flow resistances.

The cross-sectional areas of the lateral legs of the U-shaped heat exchanger (1) and/or the section connecting the lateral legs and/or the horizontal connections (14, 15) are preferably each substantially round, oval, rectangular, square, triangular or polygonal.

The surfaces of the heat exchanger (1) and/or the essentially horizontal connections (14, 15) located on the underside of the heat exchange device according to the invention are preferably at least slightly inclined in the opposite direction to the direction of the heat source (4) in order to enable condensate to drain away.

As a rule, the condensate is drained off via a downstream condensate channel. This is either located directly

with the area surrounding the heat exchange device or indirectly, for example via a device preventing the escape of the medium (2), for example a siphon-like device.
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Any electric, pneumatic or hydraulic motor as well as an internal combustion engine can be used as the adjustment device (8).
Depending on the orientation of the heat exchanger (1), it is connected to its adjustable components and/or to the casing (10), for example via a vertically or horizontally aligned and acting scissor, cable, rack and pinion or threaded rod mechanism.

Of course, it is possible to equip the heat exchange device according to the invention not only with one heat exchanger (1), but with several heat exchangers (1).

In a preferred embodiment, at least two heat exchangers (1) which are adjustable according to the invention are connected in series one after the other. One of the heat exchangers (1) comprises, for example, air as the medium (3) flowing along the outer wall, which can be supplied to the heat source (4) as preheated combustion air via a supply line.

The supply line can be routed outside and at a distance from the heat exchanger. However, to avoid heat loss, it is preferably routed

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at least partially in the horizontal connections (14, 15) of the upstream heat exchanger (1) and/or in the latter itself and/or closely adjacent thereto.

It has proven advantageous to connect a buffer storage tank to the casing (10).

Preferably, the buffer storage is connected to the usage medium (3) flowing along the outside of the heat exchanger (1) via a charging and discharging station and is charged as soon as the usage medium (3) exceeds a preset temperature.

By installing a buffer storage tank, better combustion values can be achieved, as excess energy generated during full-load operation can be absorbed. The buffer storage tank increases the efficiency of the heat exchanger (1), smooths out the temperature fluctuations of the medium flowing along the outside of the heat exchanger (1) resulting from the combustion process (3), enables more efficient boiler operation during the transition period, reduces partial load operation and reduces fuel consumption.

If the heat exchanger(s) (1) connected in series have been expanded in such a way that the escaping exhaust or flue gas only has a temperature that is no longer sufficient for proper chimney buoyancy, at least one fan (19) can be provided as a buoyancy accelerator.

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Such a fan (19) is particularly helpful when cooling the flue gas to a temperature below the dew point. The fan (19) is preferably coupled to the control element (17), which in turn is connected to a measuring probe (16) for determining the temperature of the exhaust or flue gas (2).

The fan (19) can in principle be provided anywhere in the area which upstream comprises the section before the heat source (4), the essentially horizontal connections (14, 15), at least one heat exchanger (1) and downstream, if necessary, a chimney.

The fan (19) preferably generates a flow inside the tubular heat exchanger (1) that flows from the heat source (4) in the direction of the downstream connection (15) and is directed opposite to the direction of the heat source (4). The fan exerts a pressure and/or suction effect on the medium (2) flowing inside the heat exchanger (1).

The heat source (4) can be any device whose original purpose is to generate heat or which releases heat energy only as a by-product.

As a rule, the heat source (4) is an internal combustion engine, a generator or a combustion system. 30

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It is particularly advantageous that the heat exchange device according to the invention can also comprise a combustion system for liquid and/or gaseous and/or solid fuels such as coal, briquettes, peat, lumpy wood, non-lumpy wood, straw or similar plant materials as a heat source (4).

The advantages of the heat exchange device according to the invention are particularly evident when the fuel is a solid fuel such as chopped wood.

In the case of solid fuels, the combustion plant (4) is, for example, a boiler with top combustion, a through combustion boiler, a bottom combustion boiler, a fan-controlled bottom combustion boiler, an underfeed combustion system or a degassing combustion system.

Claims (14)

Protection claims 1. Heat exchange device connected downstream of a heat source (4), characterized in that it comprises at least one essentially tubular heat exchanger (1) for transferring the heat of a medium (2) flowing within the tubular heat exchanger (1) to a medium (3) flowing along the outside of the heat exchanger (1) in the same or opposite direction, which, when viewed from the front, essentially corresponds to the shape of a letter "U" and, when viewed from the side, is oriented essentially vertically upwards or downwards or horizontally, the free end of one lateral leg of the U-shaped heat exchanger (1) being connected to the heat source (4) via a connection (14), while the free end of the other lateral U-leg is provided with a connection (15) for forwarding the medium (2) flowing within the tubular heat exchanger (1), at least the walls (5,6) of the lateral legs of the U-shaped heat exchanger (1) are designed such that their length 5 and/or the size of the surface (5,6) around which the medium (2) flowing in the interior of the tubular heat exchanger (1) flows essentially laminarly can be adjusted via an adjustment device (8) acting directly or indirectly on the heat exchanger (1). 2. Heat exchange device according to claim 1, characterized in that it comprises at least one measuring probe (16) for determining at least one characteristic feature of the medium (2) flowing inside the heat exchanger (1) and/or at least one measuring probe for determining at least one characteristic feature of the medium (3) flowing along the outside of the heat exchanger (1) and at least one control element (17) which is connected to each of the measuring probes (16) and receives from this the determined actual value of the respective characteristic feature and which is designed in such a way that it compares the measured actual value with a settable and stored target value via an input device and in the event of a deviation of the actual value from the stored target value, emits a steep value signal to the adjustment device (8) acting essentially vertically or horizontally and indirectly or directly at least on the heat exchanger (1), which the adjustment device (8) can use to causes the length of the side legs and/or the surface area (5,6) of the U-shaped heat exchanger (1) available for heat exchange to be increased or decreased and which is designed in such a way that it regulates the speed of a possibly present fan (19) in such a way that the combustion chamber (4) is supplied with at least a sufficient amount of air for optimal combustion. 3. Heat exchange device according to claim 2, characterized in that the measuring probe (16) determines the temperature and/or the concentration of CO, CO ₂ , O ₂ , NO, aromatic hydrocarbons, soot, tar, waxes, resins, dust, condensate or other components of the medium (2) as a characteristic feature of the medium (2) flowing inside the tubular heat exchanger (1) and/or that a measuring probe determines the temperature and/or the flow velocity and/or the viscosity as a characteristic feature of the medium (3) flowing outside the tubular heat exchanger (1). 4. Heat exchange device according to one of claims 1 to 3, characterized in that the heat source (4) is a furnace or an internal combustion engine, that the medium (2) flowing inside the tubular heat exchanger (1) is a flue gas heated by a furnace (4) or an exhaust gas heated by an internal combustion engine, the flow direction of which is in the same direction or opposite to the direction of the furnace (4) or the internal combustion engine, that the use medium (3) flowing along the outer wall of the tubular heat exchanger (1) is air and/or water and/or steam and/or a natural or synthetic oil, the flow direction of the use medium (3) being opposite or in the same direction to the flow direction of the medium (2), that at least one measuring probe (16) for determining the temperature of the inside of the tubular heat exchanger (1) from the furnace (4) or the The control element (17) is designed in such a way that, upon receipt of a signal transmitted by the measuring probe (16) which corresponds to a temperature which is above a certain threshold value preset via an input device, it emits an actuating signal to the adjusting device (8), which causes the adjusting device (8) to expand the U-shaped heat exchanger (1) at least partially in a vertical or horizontal direction in order to create the space required for heat exchange between the flue gas (2) which is then too hot and the heat- to increase the surface area of the heat exchanger (1) available for the colder usage medium (3) to be discharged, 0 and that the control element (17) is designed in such a way that, upon receipt of a signal transmitted by the measuring probe (16) which corresponds to a temperature which is below a certain threshold value preset via an input device, it emits an actuating signal to the adjusting device (8) which causes the adjusting device (8) to lower or compress the U-shaped heat exchanger (1) at least partially in a vertical or horizontal direction in order to create the surface area required for heat exchange between the flue gas (2) which is then too cold and the usage medium (3) which additionally discharges heat. available surface of the heat exchanger (1) so that the temperature of the smoke or exhaust gas (2) flowing out of the downstream end of the connection (15) reaches a high, preset value shortly after the combustion system (4) or the engine is started, can be kept essentially constant at a certain, preset value such as the dew point by proportionally adjusting the surface of the heat exchanger (1) to the temperature profile of the combustion, and as a result there is an effective energy release to the external, heat-dissipating medium (3) and thus a reduction in heat and exhaust gas loss, and as a result combustion materials with different calorific or heating values can be used and as a result the combustion of solid fuels with different moisture contents and piece sizes is even made possible in the calorific value range. 5. Heat exchange device according to one of claims 1 to 4, characterized in that the tubular heat exchanger (1), which essentially corresponds to the shape of a letter "U", is at least partially surrounded by a casing (10) which is essentially adapted to the U-shape of the heat exchanger (1), at least partially encloses the space (13) between the lateral legs of the U-shaped heat exchanger (1) and is at least somewhat and is at least partially spaced apart, wherein the walls of this casing (10) enclosing the lateral legs of the U-shaped heat exchanger (1) are rigid in the longitudinal direction of the lateral legs of the U-shaped heat exchanger (1) or are designed to be expandable and/or compressible in accordance with the orientation and type of the walls (5,6) of the heat exchanger (1), and wherein in the region of the upstream and downstream two ends of the casing (10) either an opening (11) for the supply or an opening (12) for the removal of the external medium (3) is provided. 6. Heat exchange device according to claim 5, characterized in that the casing (10) comprises the entire U-shaped heat exchanger (1) including at least part of the intermediate space (13) and at least parts of the connection (14) running horizontally to the heat source (4) and the downstream connection (15), whereby the heat-dissipating medium (3) flows around the enclosed parts essentially on all sides and whereby, when viewed from the front, in the space (13) between the lateral legs of the U-shaped heat exchanger (1), at least one essentially rectangular guide (18) adjustable in length is provided for guiding the medium (3) along the surfaces of the lateral legs of the U-shaped heat exchanger (1), the longitudinal axis of which is aligned parallel to the longitudinal axis of the U-shaped heat exchanger (1) when viewed from the side and which, when viewed from the front, is parallel and essentially central to the lateral legs of the u- shaped heat exchanger (1) and whose rear and front longitudinal sides are connected to the rear and front of the casing (10) in a substantially sealing manner and rigidly or at least partially displaceably in the longitudinal direction of the guide (18), wherein the end of the guide (18) pointing in the direction of the middle straight or curved section of the U-shaped heat exchanger (1) is at least somewhat spaced from this and the opposite end of the guide (18) is connected to the casing (10) in a substantially sealing manner. 7. Heat exchange device according to one of claims 1 to 6, characterized in that at least the walls (5, 6) of the lateral legs of the U-shaped heat exchanger (1) and/or the walls of the casing (10) enclosing the lateral legs of the U-shaped heat exchanger (1) have at least partially a bellows-like structure (7) which enables displacement along the longitudinal axis of the lateral legs of the U-shaped heat exchanger (1), the bellows (7) being dimensioned and mounted in such a way that they do not significantly reduce the flow cross-sections, and/or have a roller shutter-like structure with a winding device and/or comprise plates which can be displaced relative to one another in the direction of the longitudinal axis of the lateral legs of the U-shaped heat exchanger (1) and are connected to one another in a substantially sealing manner. 8. Heat exchange device according to one of claims 1 to 7, characterized in that the walls (5, 6) of the heat exchanger (1) are at least partially provided with elements for enlarging the heat exchange surface, which protrude at least somewhat into the medium (2) flowing away from the heat source (4) inside the tubular heat exchanger (1) and/or into the medium (3) flowing along the outside of the heat exchanger (1) and are designed and arranged in such a way that the media (2, 3) flow around them in a substantially laminar manner and/or that flow resistances are provided inside the tubular heat exchanger (1) and/or the substantially horizontal connections (14, 15) of the heat exchanger (1) in such a way that the core flow heated most by the heat source (4), narrow-beamed and generally centered in the middle of the tube, is fanned out and directly against the walls of the heat exchanger (1) and/or the horizontal connections (14,15). 9. Heat exchange device according to one of claims 1 to 8, characterized in that the lateral IT legs of the heat exchanger (1) and/or the section connecting the lateral legs of the U-shaped heat exchanger and/or the horizontal connections (14, 15) each have substantially round, oval, rectangular, square, triangular or polygonal cross-sectional areas and/or that the surfaces of the heat exchanger (1) and/or the substantially horizontal connections (14, 15) located on the underside of the heat exchange device are opposite to the direction of the heat source (4) are at least slightly inclined to allow condensate drainage, wherein the condensate is discharged via a downstream condensate channel which is directly connected to the area surrounding the heat exchange device or via a device preventing the medium (2) from escaping. 10. Heat exchange device according to one of claims to 9, characterized in that the adjusting device (8) is connected to the adjustable components of the heat exchanger (1) and/or to the casing (10) via a vertically or horizontally aligned and acting scissor, cable, rack or threaded rod mechanism. 11. Heat exchange device according to one of claims to 10, characterized in that at least two heat exchangers (1) according to one of the preceding claims are connected in series, one behind the other, one of the heat exchangers (1) comprising air as the medium (3) flowing along the outer wall, which is supplied to the heat source (4) as preheated combustion air via a supply line which runs outside and at a distance from the heat exchange device or, in order to avoid heat loss, at least partially in the horizontal connections (14, 15) of the upstream heat exchanger (1) and/or in the latter itself and/or closely adjacent thereto. 10 12. Heat exchange device according to one of claims 1 to 11, characterized in that in order to smooth out the temperature fluctuations resulting from the combustion process of the use medium (3) flowing along the outside of the heat exchanger (1), to increase the efficiency of the heat exchanger (1), to reduce the partial load operation during the transition period and to reduce fuel consumption, a buffer storage device is provided which is connected to the use medium (3) flowing along the outside of the heat exchanger (1) via a loading and unloading station and is loaded as soon as the use medium (3) exceeds a preset temperature. 13. Heat exchange device according to one of claims 1 to 12, characterized in that in the area which upstream comprises the section before the heat source (4), the essentially horizontal connections (14, 15), at least one heat exchanger (1) and downstream if necessary a chimney, at least one fan is provided, which is optionally coupled to the control element (17) and in the flow direction of the inside of the tubular heat exchanger (1) opposite to the direction of the heat source (4) flowing medium (2) and exerting a pressure and/or suction effect on it. 11 14. Heat exchange device according to one of claims 1 to 13, characterized in that the heat source (4) is a firing system for liquid and/or gaseous and/or solid fuels such as coal, briquettes, peat, lumpy wood, non-lumpy wood, straw or similar plant materials, whereby in the case of solid fuels the firing system (4) is a boiler with top combustion, a through combustion boiler, a bottom combustion boiler, a fan-controlled bottom combustion boiler, an underfeed firing system or a degassing firing system.