DE29724316U1 - Device for exchanging heat (segment coil) - Google Patents

Description

: filijbl.-lng. (FH) Hans-Peter Höcker ·* ** Hauptstraße 17

91091 Großenseebach

Description:

The invention relates to a device for exchanging heat.

In DE 43 25 193 Figure 1 by the same inventor, a heat exchanger is shown which consists of a twisted guide device for the first medium on the inside and a jacket pipe for the second medium on the outside. However, the guide device (coil) mentioned can only be manufactured with great effort and the possible number of helical revolutions (number of twists) is limited. The effect of the heat transfer can be greatly reduced because the length of the screw path (transfer length) is limited. The effectiveness can be poor particularly with larger widths or diameters of the coil because a great deal of effort is required when twisting and the number of twists is therefore very low due to the manufacturing process. The deformation of the guide device (coil) can become so great that it breaks out of the screw path and thus becomes unusable. When the guide device is used as an exhaust gas heat exchanger in engines, the sound-damping effect is also very low.

It is therefore the object of the invention to design a device for exchanging heat between a first and a second flowable medium in such a way that it avoids the disadvantages of the known prior art. It should achieve a higher level of efficiency and have a sound-damping effect.

The problem is solved by a device having the features of the main claim.

The inventive guide device can be manufactured, as in the prior art, for example from a commercially available flat steel by simply twisting it. In order to increase the efficiency of the guide device compared to the prior art, cuts are made on the edges of the guide device before twisting. These cuts reduce the effective width of the guide device when twisting. This means that a significantly

• · "!* »..Bipiiltig-(FH) Hans-Peter Höcker ** ** ** Hauptstraße

91091 Großenseebach

less force is required and the helical revolutions (twist number) increase. Increasing the twist number increases the effective length of the helical path in the pipe. The residence time of the first medium in the heat exchanger increases and thus the heat can be transferred more effectively to the inner pipe and thus to the second medium.

Since the guide device (helix) deforms into individual segment-like bodies (so-called segments) when twisted in the area of the incisions, a helical fanning out of the outer edge of the guide device occurs in the area of the incisions.

The fanned-out segments that lie against the inner tube prevent a laminar flow from forming on the spiral. The strong turbulence that occurs in the area of the segments allows the medium on the inner tube to cool down particularly well and the heat can be transferred very well via the inner tube to the second medium in the outer casing.

The cuts on the helix are normally arranged at a 90 degree angle to create rectangular segments.

However, if the cuts in the coil are not made at a 90 degree angle to the outer edge of the guide device, but the angle is varied to 30 degrees or 45 degrees, for example, diamond-shaped or trapezoidal segments are created. The efficiency of the heat exchanger can be varied by arranging the segments in different geometric shapes.

When using the guide device (segment spiral) as an exhaust gas heat exchanger in diesel engines, the turbulence that occurs on the segments results in less soot deposits than with spirals without segments. This has a self-cleaning effect. The maintenance intervals can therefore be extended.

• .· : : **: &iacgr; Bipl.-Ing. (FH) Hans-Peter Hocker ·· " * Hauptstraße17

91091 Großenseebach

When the guide device is used as an exhaust heat exchanger for engines, the turbulence in the segments results in a sound-dampening effect. The exhaust silencer that is normally installed downstream can be made smaller under certain circumstances.

In order to be able to easily remove the guide device for maintenance and cleaning work, at least one inspection opening is provided in the axial direction. Because the outer edges of the guide device with the segments rest on the inner surface of the tubular body, this inner surface is cleaned when the guide device is pulled out. Any soot particles that may adhere when used as an exhaust gas heat exchanger are also stripped off. In order to be able to move the coil more easily during cleaning work, a hole is provided at the end of the coil into which a tool (hook) can be hooked so that the coil can be easily pulled out and reinserted. By pushing the coil back and forth several times, the inner pipe of the heat exchanger is very well cleaned by the segments and the heat can therefore be fully transferred again when the heat exchanger is used again.

Further details of the invention emerge from the subclaims and from the description of embodiments, which are explained in detail below with reference to the drawings. It shows:

Figure 1 shows a longitudinal section through the device according to the invention and Figure 2 shows a cross section through the device according to the invention according to Figure 1.

The inner tube 1 is connected on one side to the inlet nozzle 5 and on the other side to the outlet nozzle 3 located on the side. The opening 8 is arranged in the axial direction to the inner tube 1 and has a closure 4. The inner tube 1 is connected to the jacket tube 6 and has a common cavity 7.

i _## Sip^-lng. (FH) Hans-Peter Höcker ** Hauptstraße 17

91091 Großenseebach

The jacket tube 6 can, as shown in Figure 2, be manufactured with either a radial or a rectangular or square cross-section (6 or 9). However, the choice of cross-section has practically no influence on the functioning of the heat exchanger.

The casing pipe 6 has a radial inlet nozzle 11 and a radial outlet nozzle 10. The inlet and outlet nozzles 11 and 10 of the casing pipe 6 are arranged in such a way that an exhaust gas from an internal combustion engine guided through the inner pipe 1 flows in the opposite direction to a liquid guided through the cavity 7. Within the inner pipe 1 there is a spirally twisted steel band serving as a guide device 15, the outer longitudinal edges of which rest against the inner surface of the pipe 1. Incisions 12 are made on the edge of the steel band transverse to the flow direction of the exhaust gas. These incisions 12 divide the outer region of the steel band into individual turbulence-generating segments 13, which remain connected to the steel band.

If a hot exhaust gas from an internal combustion engine is now introduced into the pipe 1 through the inlet nozzle 5, it is subjected to a helical swirl via the coil 15, which repeatedly brings it into contact with the pipe wall 1 and thus ensures good heat transfer. In order to prevent a laminar flow from developing, the incisions 12 and the turbulence-generating segments 13 are provided, which ensure a constant swirling of the exhaust gas in the outer area of the coil 15. The speed of the exhaust gas is greatly increased in the area of the segments 13 and becomes highly turbulent. This increases the heat transfer to the inner pipe 1 and the efficiency of the heat exchanger increases. The heat given off by the exhaust gas goes into the wall of the pipe 1 and is then dissipated via the flowing medium in the cavity 7.

If soot or dirt deposits have formed in the pipe 1 after prolonged use, the heat exchanger can be cleaned in a simple manner.

.· / : I **! &Sgr; ©ipl.-lfig. (FH) Hans-Peter Hocker

Main Street 17

91091 Großenseebach

the closure 4 is removed and the coil 15 can be pulled out through the opening 8 that is created. To make this easier, a hole 2 is provided into which a suitable tool can be hooked. When the coil 15 is pulled out, the segments 13 that lie close to the inner wall of the pipe 1 scrape off the soot or dirt deposits and transport them out through the axial opening 8. By repeatedly pushing the coil 15 back and forth, practically all dirt is removed, so that the efficiency of a new heat exchanger is achieved again. Due to the way the turbulence-generating segments 13 work and the high flow speed of the exhaust gases in the area of the segments 13, less or no dirt or soot settles on the inner pipe 1 and the heat exchanger has to be cleaned less often.

If it is determined after the coil 15 has been manufactured that the efficiency of the heat exchanger is too low, the efficiency can be increased by twisting the coil 15 more. This makes the effective helical path of the exhaust gas through the heat exchanger longer and the residence time of the exhaust gas on the segments 13 increases. If it is determined after the coil 15 has been manufactured that the efficiency of the heat exchanger is too high, the efficiency can be reduced by twisting the coil 15 less. This makes the effective helical path through the heat exchanger shorter and the residence time of the exhaust gas on the segments 13 decreases. The aforementioned change (modulation) in the efficiency of the heat exchanger can be increased even further. For example, the incisions 12 between the segments 13 can be made deeper or less deep. This changes the effective width of the coil 15 and the effort required to twist it becomes less or more. This in turn increases or decreases the number of twists. A good value in practice is obtained with a total depth of the incisions 12 on both sides of approx. 40% based on the total width of the helix 15. Only 60% of the material has to be deformed during the twisting.

Claims (8)

1. Device for exchanging heat from a first flowable medium to a second flowable medium with a tubular body 1 , which has in its interior a guide device 15 for the first flowable medium and both an inlet 5 and an outlet 3 for it and with a casing 6 which forms a cavity 7 with the tubular body 1 and has both an inlet 11 and an outlet 10 for the second flowable medium, wherein the tubular body 1 has a closable opening 8 through which the guide device 15 can be pulled out and wherein the guide device 15 consists of an elongated metal or plastic band which is twisted in a spiral manner about its longitudinal central axis and rests with its regularly arranged incisions 12 and segments 13 on the inner surface of the tubular body 1 in such a way that when the guide device 15 is pulled out through the closable opening 8, deposits from the inner wall of the tubular body 1 through the segments 13 are scraped off and transported outwards through the opening 8 . 2. Device according to claim 1, wherein on the outer edge of the guide device 15 incisions 12 are made, which are made at irregular intervals. 3. Device according to claim 1, wherein on the outer edge of the guide device 15 incisions 12 are provided, which are made with different depths. 4. Device according to claim 1, wherein on the outer edge of the guide device 15 incisions 12 are provided, which are designed with different widths. 5. Device according to claim 1, wherein the incisions 12 are arranged at different distances. 6. Device according to claim 1, wherein the incisions 12 are arranged at different angles to the outer edge of the guide device 15 . 7. Device according to claim 2, in which the incisions 12 create turbulence-generating segments 13 which are designed in different sizes. 8. Device according to claim 2, wherein the incisions 12 arranged at different angles create segments 13 which in turn are arranged at the corresponding different angles.