DE1087291B - Electric tubular heater with enlarged heat-emitting surface - Google Patents

Description

GERMAN

The invention relates to electric tubular heating elements with an enlarged heat-emitting surface.

The need arises when solid, liquid or gaseous media are heated by electric tubular heating elements on, the largest possible amount of electricity generated by a radiator with energy to transfer small external dimensions to the medium to be heated. Apart from the installation method the tubular heating element and the material-related thermal parameters, the maximum Transferable power or amount of heat mainly due to the electrical surface load Determined power per unit of the heat emitting radiator surface. A high surface load of the electric tubular heater leads under otherwise identical heat transfer conditions to a high temperature of the tubular heater. Conversely, by increasing the Heat-emitting tubular heating element - surface the temperature of the tubular heating element surface is reduced which is sought in many cases for electrical and thermal reasons.

The previously known embodiments of tubular heaters, in which it was attempted, the heat-emitting Surface of the metallic pipe jacket by sheet metal ribs or by enlarging the surface "Profiling" of the pipe jacket to increase, have a number of disadvantages, which result had that these tubular heating elements are not widely accepted in practice could.

Thus, for surface enlargement, In particular, sheet metal ribs running perpendicular to the pipe axis control the flow, in particular in the direction hinder the pipe axis. Tubular heating element with sheet metal ribs that run particularly along the axis of the tube cannot be bent into the shapes required for tubular heating elements after the ribs have been applied will.

The previously known methods, the heat-emitting surface by rolling or pressing special Enlarging tubular profiles to the required size was not possible on finished tubular heating elements can be made without significantly impairing the electrical properties. Will this Profiles, however, applied before the final production of the tubular heating element, these profile tubes can are not compressed or processed in the manner required for tubular heating elements.

The invention has set itself the task, with a simple design of the surface-enlarging Means to avoid these disadvantages.

The invention is based on an electric tubular heater with enlarged heat-emitting upper

Electric tubular heater

with enlarged heat emitting

surface

Applicant:

CERU electrical heating company

Czepek & Co.,

Hausen via Offenbach / M.,

Freiligrathstrasse 6-10

Rudolf Scherbach and Dipl.-Ing. Rudolf Czepek,

Frankfurt / M.,
have been named as inventors

surface which is in good thermal contact with the pipe jacket additional metal parts is achieved. It consists in the fact that, according to the invention, the metal parts consist of a co-

a5 axial, tightly attached, made of wire, pipe or one or more electrical tubular heaters made helical winding exist. Of the Wire of this helical winding can preferably be circular, oval or rectangular Have cross-section, as well as the tube or the tubular heating element (s), which for the helical Winding come into question. The helical winding is either wound tightly onto the tubular heating element or pushed over the tubular heating element as a pre-wound coil. The good heat transfer between Pipe jacket and helical winding are made by shrinking, pressing, hammering, welding, Soldering or, im. Course of the surface treatment of the tubular heater, through metallic deposits achieved.

The slope of the helical turns of the surface-enlarging winding is expediently 1.5 to 15 times the diameter of the wire or pipe or tubular heater which the surface-enlarging winding is made.

The diameter of the helically tightly attached wire, pipe or des Tubular heater. is preferably 0.1 to 1 times the outer diameter of the tubular heater, whose surface is to be enlarged.

The advantages of the invention are particularly significant when flowing liquids in relatively small containers should be heated quickly.

009 587/371

The helical winding with those described above Features increases the heat-emitting surface of the tubular heater to such an extent that that the power per unit of the tubular heater length due to the reduced pipe jacket temperature can be increased to a multiple of the previously customary specific performance values. Simultaneously favors the helical arrangement of the coaxial, preferably made of round wire Wire winding the intensive flushing of the tubular heating element with the flowing past and to be heated liquid or gaseous medium.

If the surface-enlarging helical winding consists of a tubular heating element, then there is a Another advantage of the invention is that, in addition to increasing the surface area, a distribution or Branching of the electrical power is achieved. In certain cases it is worth striving for Heating conductor of the tubular heater whose surface is to be enlarged, electrically as low as possible to charge. By using a tubular heater as a winding and increasing the surface area by electrical parallel or series connection of a heating conductor with the heating conductor of the wound one The tubular heating element takes over the surface-enlarging helical winding part of the Heating output, the heating conductor of the wound tubular heating element works with reduced surface load and assumes a relatively low temperature.

The invention is illustrated by way of example in the drawing.

Fig. 1 shows the plan view of a U-shaped bent tubular heater with a surface enlarging Winding, which is arranged in the form of a round wire helix close to the pipe jacket is;

Fig. 2 shows a tubular heater whose surface-enlarging winding consists of an electrical Tubular heating element.

1 is the metallic tubular jacket of the wound tubular heater, 2 is made of round wire, for example produced helical winding, which is tightly connected to the pipe jacket and at simultaneous improvement of the flooding in the case of media flowing in the direction of the pipe axis Surface enlargement of the tubular heater 1 causes. 3 and 4 are the electrical connections of the wound tubular heating element.

According to FIG. 2, the helical winding 2 consists of a tubular heating element. The connection end 5 of the helical tubular heater is connected to the connection end 4 of the wound tubular heater. In the case of the series connection shown for example, the power is connected to the connection ends 3 and 6. In a similar way, the two tubular heating elements can also be connected in parallel or connected in a switchable series-parallel connection. The additional tubular heating element can also act as a return conductor. In this case, 2 is a heat conductor material is conveniently carried out either for the wrapped tubular heating element 1 or for the helically coiled tubular heating element 2, or to both tubular heater 1 is used, the electrical resistance at elevated temperature so greatly increases _r that a temperature increase of 100 ° C, an increase in resistance of at least 20 ° /" is equivalent to. The use of heating conductor alloys with a highly temperature-dependent electrical resistance for the tubular heater 1 or 2 or 1 and 2 brings particular advantages with regard to the automatic power control in the arrangement according to the invention according to FIG. 2 because of the different heating conductor temperatures in the two tubular heating elements.

7 is the tapered end of the tubular heater 1. It is after the connection of the two connection ends 4 and 5 are tightly connected to one end of the coiled tubular heating element 2. In this way Both power connections 3 and 6 are at one end of the entire radiator, and this can be used as cartridges - Immersion heaters can be used.

Claims (6)

Patent claims: 1. Electric tubular heater with enlarged heat-emitting surface, which through on Additional metal parts attached to the pipe jacket and in good thermal contact with it is achieved, characterized in that the metal parts from a coaxial, tightly applied, from Wire, pipe or one or more electrical tubular heating elements produced helical Winding. 2. Electrical tubular heater according to claim 1, characterized in that the wire, the tube or the electrical tubular heating element (s) for the helical winding is circular Have cross-section and the helical winding has a slope, which is preferably 1.5 to 1 times the wire or tube or pipe jacket diameter. 3. Electrical tubular heater according to claims 1 and 2, characterized in that the Diameter of the wires, pipes or tubular heating elements of the helical, enlarging the surface Winding is 0.1 to 1 times the outer diameter of the pipe jacket. 4. Electrical tubular heater according to claims 1 to 3, in which the enlargement of the heat emitting Surface-causing helical winding consists of one or more tubular heating elements, characterized in that that the coiled or elongated heating conductor of the tubular heating element or the helical Winding in series or parallel connection or in switchable series-parallel connection with the heating conductor of the electric tubular heater, the surface of which is increased are. 5. Electrical tubular heater according to claim 4, characterized in that on his one end both the heating conductor electrical and the pipe jackets of the coiled and the wrapped Tubular heater are tightly connected to each other and that merge the electrical power connections of both tubular heating elements are at the other end. 6. Electrical tubular heater according to claims 4 and 5, characterized in that either for the wrapped or for the helically wound or for both tubular heating elements a heating conductor material is used, the electrical resistance of which at increased temperature increases so much that a temperature increase of 100 ° C an increase in resistance of at least Corresponds to 20%. 1 sheet of drawings © i 009 587/371 8.60