WO2008106971A1 - Heating-oil prewarming device - Google Patents

Abstract

The invention relates to a prewarming device for heating oil (1), comprising at least one heating element (2) with a heating surface (9) and at least one oil conduit housing (5) that has at least one oil conduit (11) with a first delimiting wall, the exterior of which lies against the heating surface (9). The aim of the invention is to provide a prewarming device for heating oil of this type with a simple construction. To achieve this, the oil conduit housing (5) in at least one region in which the heating element lies against said housing (5) is designed as an aluminium section, the interior of which has at least one thermally conductive wall (10) projecting from the delimiting wall (7).

Description

 Heizölvorwärmer

The invention relates to a Heizölvorwärmer with at least one heating element, which has a heating surface, and at least one ölkanalge- housing having at least one oil passage with a first boundary wall, the outside of which abuts the heating surface.

Such Heizölvorwärmer is known for example from DE 42 16 008 A1. The oil passage housing has an oil passage, are arranged in the heat conducting body. These heat-conducting body can have different shapes. Proposed are a good heat-conducting porous material or a separately formed shaped body made of sintered bronze.

US 4,447,706 shows an oil preheater in which the oil passage housing is formed by a Flachkantrohr. Alternatively, you can also cut out flat channels in a plastic or provide tightly adjacent holes in a plastic.

DE 2422 216 A1 shows a nozzle rod for an oil burner, in which the heating is performed by heating elements which extend axially to an oil feed pipe. Alternatively, one can use heating elements that are wound around the oil feed tube. These heating elements are cast in a heat storage aluminum.

DE 198 59 014 A1 shows an oil preheater, which is composed of a plurality of elements, namely a tube, an outer Wärmevertei- management element and an inner heat distribution element, wherein a heating resistor is in heat-conducting connection with the outer heat distribution element. Heating oil preheaters are used to raise the fuel oil supplied to an oil burner to an elevated temperature. This increased temperature reduces the viscosity of the heating oil and facilitates its atomization. The better the fuel oil is atomized, the lower the environmental impact of burning the heating oil.

The known Heizölvorwärmer are relatively expensive to manufacture. In order to allow a good heating of the heating oil, the flow cross sections, through which the heating oil can flow, kept as small as possible. The smaller these cross-sections are, the greater the risk that the heating oil preheater becomes clogged, thus overloading the heating oil pump during operation.

The invention has for its object to realize a Heizölvorwärmer with a simple structure.

This object is achieved in a Heizölvorwärmer of the type mentioned above in that the oil passage housing is formed at least in a region in which the heating element on the oil passage housing, as an aluminum profile having at least one protruding from the boundary wall in the heat-conducting wall.

With this configuration, it is achieved that you have to handle only a single element at a relatively large heat transfer surface, namely the aluminum profile. The aluminum profile has two tasks. It surrounds the oil channel. Heat can then be transferred to the heating oil through the boundary wall of the oil channel. The heat transfer is further improved by the fact that protrudes from the boundary wall, the heat conducting wall inwards into the oil passage. Since the oil passage housing is formed overall as an aluminum profile, the heat conducting wall is integrally connected to the boundary wall, so that a heat flow from the heating element to the boundary wall and of There is possible on the Wärmeleitwand without major losses. This makes it possible to make the free cross section, through which the fuel oil can flow, a little larger. This reduces the risk that the heating oil preheater gets clogged. At the same time, there is less pressure drop over the heating oil preheater, which helps to protect the oil pump. There is comparatively little material used. By using an aluminum profile, the manufacturing costs are kept low. In addition, the use of aluminum is beneficial because it is much more resistant to bio-oils, ie biofuels, than copper or brass. The slightly lower thermal conductivity of aluminum compared to copper or brass can be compensated by a corresponding dimensioning of the heat conducting wall.

Preferably, the heat-conducting wall connects the first boundary wall with a second boundary wall, which lies opposite the first boundary wall. The Wärmeleitwand then has a second function. It not only serves to transfer heat to the fuel oil that flows along the heat-conducting wall. The Wärmeleitwand also serves the mechanical support of the second boundary wall with respect to the first boundary wall, so that for example on the second

Limiting wall can apply a force with which the oil channel housing is pressed against the heating element and the greater this force, the better the heat transfer between the heating element and the oil channel housing in general. This force can then be applied for example by a spring. The heat conducting wall divides the oil channel into several channels.

Preferably, a plurality of Wärmeleitwände from the first boundary wall and a mean distance between the Wärmeleitwänden is provided which is smaller than a mean extent of the Wärmeleitwände of the first boundary wall away. If several heat conducting walls are provided, one can in a preferred embodiment make the distances between the Wärmeleitwänden equal. This then ensures a relatively even distribution of the fuel oil to the spaces between the Wärmeleitwänden. However, equal distances are not absolutely necessary. If the distances are not equal, then a mean distance is formed by dividing the sum of the distances by the number of distances. In the same way, it is generally advantageous if the Wärmeleitwände the same "height", ie extension away from the first boundary wall, have. But this is not mandatory. If they do not have the same extension, then a mean extension is formed from the sum of the extensions of all the heat-conducting walls divided by the number of heat-conducting walls. If one now chooses the average extent greater than the average distance between the Wärmeleitwänden, then there is a relatively large heat transfer surface for the fuel oil at a rela-5 tively small layer thickness of the fuel oil. Thus, a good heating of the fuel oil can be achieved even if the Heizölvorwärmer has only a limited length in the flow direction of the fuel oil.

The average extension of the heat-conducting walls of o of the first boundary wall is preferably 3 to 4 times the mean distance. This results in a flow path for the heating oil between two Wärmeleitwänden, which has a rectangular cross section in principle. The rectangle formed by the cross-section has a broad side which is about 3 to 4 times the height of the rectangle. This allows a satisfactory heat transfer.

Preferably, the heat conducting walls have an average thickness which is in the range of 0.5 to 1, 2 times the average distance. The heat conducting walls need not have the same thickness, although this is advantageous. The average thickness is then calculated from the sum of the thicknesses divided by the number of heat conducting walls. The thickness is the extension of a Wärmeleitwand parallel to the first boundary wall. By the ratio between the average thickness and the distance you can take advantage of the available space in the oil channel housing particularly well. On the one hand, a satisfactory heat conduction through the Wärmeleitwände is ensured. On the other hand, it is ensured by the limitation of the thickness of the Wärmeleitwände. That there is also enough space through which the fuel oil can flow in the heating oil preheater.

Preferably, at least one heat-conducting wall limits a section of the oil passage that is essentially triangular in cross-section. By choosing a "triangle" for the section of the oil channel is achieved even then a good heat transfer and thus a satisfactory temperature for the fuel oil when spatially unfavorable conditions.

This is especially true when the substantially triangular portion of the oil passage forms a laterally outer portion of the oil passage. In this case, you can form the oil channel housing approximately trapezoidal.

Preferably, the oil passage housing has at least one end portion into which the aluminum profile is inserted. This facilitates the production. Basically, only a few parts are required for the heating oil preheater. In addition to the heating element, you need the oil channel housing and two end sections that are simply put together. The end portion has the task to connect the oil passage housing with a supply or discharge for the fuel oil. In addition, the end section has the task of distributing the heating oil as evenly as possible over the cross section of the oil channel housing.

In this case, it is preferred that the end section has a plug-in space with an end face provided with an opening, into which the aluminum section profile is inserted with a distance to the front side. The insertion space then forms the connection between the opening and the oil channel housing. The fuel oil which enters the insertion space through the opening can then spread over the cross section of the oil passage housing and thus flow through the oil channel housing with the corresponding distribution. At the other end of the oil channel housing, the fuel oil is then collected in the insertion space before it can flow through the opening in the end face.

Preferably, the end portion is formed of cold pressed aluminum. The use of aluminum for the end section has the advantage that at least substantially the same coefficient of thermal expansion is obtained for the end section and the oil channel housing. Even with temperature changes that result in operation, thermal stresses are then avoided or at least kept small. Aluminum can be brought into the desired shape by means of cold pressing without the need for complex metal-cutting shapes. By cold pressing the end section also gets a sufficient mechanical strength.

Preferably, the aluminum profile and the end portion are soldered, welded or glued together. This can be omitted a seal between the aluminum profile and the end portion. The tightness is rather generated by the connection between the aluminum profile and the end portion.

Preferably, the outside is at least partially flat. This makes it easier to bring the heating element and the oil channel housing to each other to the plant.

Alternatively or additionally, it can be provided that the outside is at least partially curved. This is especially advantageous if the Outside and the heating element with their shapes are adapted to each other, so that here too a flat contact can be made. By contrast, a curvature ensures that the heating element can be displaced laterally relative to the oil channel housing.

It is preferred that the outer side at least partially has a circular curvature. A circular, more precisely a cylindrical curvature can be easily produced with the required accuracy.

Preferably, the outside has a concave curvature. In this curvature then the heating element can be inserted. The heating element can then, for example, have a cylindrical shape, the radius of the cylinder matching the radius of the curvature.

Preferably, the Heizölvorwärmer on two aluminum profiles, between which the heating element is arranged. You can then press the two aluminum profiles against each other, for example by means of a spring, so that both aluminum profiles are pressed against the heating element.

The invention will be described below with reference to preferred embodiments in conjunction with the drawing. Herein show:

1 is a Heizölvorwärmer in section,

2 shows an end portion of the heating oil preheater,

3 shows the heating oil preheater in a partially cut-away perspective view,

Fig. 4 shows a modified embodiment of a Heizölvorwärmers. An illustrated in FIGS. 1 and 3 Heizölvorwärmer 1 has a heating element 2, which may be formed for example as a PTC element. The heating element 2 is supplied with electrical energy via connecting lines 3, 4. Since it changes its electrical resistance with temperature, the heating element 2 acts largely self-regulating, ie it can be kept at a certain temperature.

1 and 3 has two Ölkanalge- housing 5, which are inserted into two end portions 6. Each oil channel housing 5 is designed as an aluminum profile, which can be produced for example by extrusion. To produce a Heizölvorwärmer 1, it is only necessary to separate a desired length of an aluminum profile. This separated part is then inserted together with the heating element 2 in the end portions 6. The oil channel housing 5 are then soldered, glued or welded to the end sections 6. Thus, the Heizölvorwärmer 1 is completed in principle. The end sections 6 can ensure that the two oil channel housings 5 are pressed against the heating element 2 with sufficient force. If this is not the case, then you can use a non-illustrated bracket to press the two oil channel housing 5 against the heating element 2.

Both oil channel housing 5 are formed the same, so that only one will be described below.

Each oil channel housing has a first boundary wall 7 and a second boundary wall 8. The outside of the first boundary wall 7 abuts against the heating element 2, wherein the surface on which the oil channel housing 5 bears against the heating element 2 is referred to as the heating surface 9. When, as shown in FIG. 1, the heating oil preheater 1 has two oil channel housing 5, then the heating element 2 accordingly has two heating surfaces. 9

From the first boundary wall 7 are more heat conduction walls 10 approximately perpendicular. The heat-conducting walls 10 connect the first boundary wall 7 with the second boundary wall 8. Accordingly, forces exerted on the second boundary wall 8 are transmitted through the heat-conducting walls 10 to the first boundary wall 7.

Between the Wärmeleitwänden 10 channels 11 are formed, can flow through the fuel oil. In this flow heat is generated by the heating element 2, transmitted via the first boundary wall 7 and the heat-conducting walls 10 to the fuel oil flowing through.

The Wärmeleitwände 10 all have approximately the same distance a from each other. If the distances a are not equal, then, for the purposes of the following explanation, one may consider a mean distance that results from the sum of the distances a divided by the number of distances a.

Furthermore, the heat-conducting walls 10 have a thickness d. The thicknesses d of the Wärmeleitwände 10 are also the same. If this is not the case, then an average thickness is considered that results from the sum of the thicknesses d of the heat-conducting walls 10 divided by the number of heat-conducting walls 10.

Finally, the heat conducting walls 10 have an extension e of the first boundary wall 7 away. These extensions are the same for almost all Wärmeleitwände 10. From Fig. 1 it follows that the two outer Wärmeleitwände 10 'have a smaller extension. Here, too, one can consider a mean extent of the heat-conducting walls 10, 10 '. th, which is the sum of the extensions e of the Wärmeleitwände 10, 10 'divided by the number of Wärmeleitwände 10, 10' results.

A favorable dimensioning results when the average distance a between the heat-conducting walls 10 is smaller than the average extent e of the heat-conducting walls 10, 10 'of the first boundary wall. This results in rectangular channels 11, in which the "broadside" is available for heat transfer from the oil channel housing to the fuel oil flowing through. At the same time, the "layer thickness" of the heating oil, which must be penetrated by the heat, kept small. The mean extension should be 3 to 4 times the mean distance a.

The heat conducting walls 10 preferably have an average thickness d which is in the range 0.5 to 1.2 times the mean distance a. The thickness d of the Wärmeleitwände 10, 10 'is chosen so that on the one hand, a sufficiently large cross section for the heat conduction available, on the other hand, not too much material is used. It is in a given volume enough flow area for the flowing fuel oil available.

The two outer channels 11 ^* in each oil passage housing 5 are substantially triangular shape. Each oil channel housing then has an approximately trapezoidal cross-section. This makes it easier to accommodate the Heizölvorwär- mer 1 in a cylindrical envelope, which is often desired.

The end portion 6 has an opening 12 which is arranged in an end face 13. Through the opening 12 in an end portion 6 fuel oil can flow. Through the opening 12 in the other end portion 6, the heated fuel oil can flow. The end portion 6 has for both oil passage housing 5 each have a plug-in space 14 into which the respective oil passage housing 5 can be easily inserted. A tight connection results from the above-mentioned soldering, gluing or welding.

As can be seen in particular from Fig. 3, remains after insertion of the oil channel housing 5 in the end portion 6, a distance 15 to the end face 13. In this distance 15, a distribution space is formed, is distributed by the fuel oil from the opening 12 that it can pass through all channels 11, 11 'substantially evenly. However, an exactly uniform distribution is not required.

Fig. 4 shows a modified embodiment. While in the embodiment according to FIGS. 1 to 3, the heating element 2 has a cuboid shape, the heating element 2 in the embodiment according to FIG. 4 has a cylindrical shape. Accordingly, the heating surface 9 is circular in cross-section and convex. The oil channel housing 5 has a first boundary wall 7, which is concave with the same radius. In this case, the Wärmeleitwände 10 extend substantially in the radial direction.

Claims

claims 1. Heizölvorwärmer with at least one heating element, which has a heating 5 surface, and at least one oil passage housing having at least one oil passage with a first boundary wall, the outside of which abuts the heating surface, characterized in that the oil passage housing (5) at least in one Area in which the heating element (2) rests against the oil passage housing (5) is formed as an aluminum profile having inside at least one of the boundary wall (7) projecting heat-conducting wall (10). 2. Heizölvorwärmer according to claim 1, characterized in that the Wärmeleitwand (10) connects the first boundary wall (7) with a second boundary wall (8), which is opposite to the first boundary wall (7). 3. Heizölvorwärmer according to claim 1 or 2, characterized in that a plurality of Wärmeleitwände (10) of the first boundary o wall (7) protrude and a mean distance (a) between the Wärmeleitwänden (10) is provided, which is smaller than one average extension (e) of the Wärmeleitwände (10) of the first boundary wall (7) away. 5 4. Heizölvorwärmer according to claim 3, characterized in that the average extent (e) of the Wärmeleitwände (10) of the first boundary wall (7) away is 3 to 4 times the mean distance (a). 0 5. Heizölvorwärmer according to claim 3 or 4, characterized in that the Wärmeleitwände (10) have an average thickness (d), the in the range of 0.5 to 1, 2 times the average distance (a). 6. Heizölvorwärmer according to one of claims 1 to 5, characterized 5 characterizes that at least one heat-conducting wall (10) in the Cross section substantially triangular section (1 1 ¹ ) of the 01- channel limited. 7. Heizölvorwärmer according to claim 6, characterized in that0 of the substantially triangular portion (11 ¹ ) of the oil passage forms a laterally outer portion of the oil passage. 8. Heizölvorwärmer according to one of claims 1 to 7, characterized in that the oil channel housing (5) has at least one end-5 section (6), in which the aluminum profile is inserted. 9. Heizölvorwärmer according to claim 8, characterized in that the end portion (6) has a Einsteckraum (14) with an opening (12) provided with an end face (13), in which the aluminum umprofilprofil with a distance (15) End face (13) is inserted. 10. Heizölvorwärmer according to claim 9, characterized in that the end portion (6) is formed of cold pressed aluminum. 5 11. Heizölvorwärmer according to claim 9 or 10, characterized in that the aluminum profile and the end portion (6) are soldered together, welded or glued. 12. Heizölvorwärmer according to any one of claims 1 to 11, characterized o characterizes o that the outside is at least partially flat. 13. Heizölvorwärmer according to one of claims 1 to 12, characterized in that the outer side is at least partially curved. 14. Heizölvorwärmer according to claim 13, characterized in that the outer side at least partially has a circular curvature. 15. Heizölvorwärmer according to claim 14, characterized in that the outer side has a concave curvature. 16. Heizölvorwärmer according to one of claims 1 to 15, characterized in that it comprises two aluminum profiles, between which the heating element (2) is arranged.