Winding with optimized heating surface
By employing structured uprights with inclined sections in heating devices, the heating surface area loss is minimized, and the effective heating surface is optimized, addressing the inefficiencies of smooth cylindrical uprights.
Patent Information
- Application Number
- FR2023013752
- Authority / Receiving Office
- FR · FR
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2023-12-07
- Publication Date
- 2025-06-13
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing heating devices with smooth cylindrical uprights suffer from a loss of heating surface area due to the trapezoidal shape of the winding, which does not match the rectangular surface of the device, and additional losses from the spacing between turns.
The use of structured uprights with sections that include rounded cylindrical or truncated cone-shaped parts, where the ribbon makes a U-turn, and the sections are inclined at an angle alpha prime, optimizing the heating surface to be inscribed in a rectangle.
This configuration minimizes the loss of heating surface area by eliminating the trapezoidal shape and reducing the spacing losses between turns, thereby maximizing the effective heating surface.
Smart Images
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Abstract
Description
Title of the invention: Winding with optimized heating surface
[0001] FIELD OF THE INVENTION The present invention relates to a device for electrically heating premises by means of a winding of electrically heated tape in the form of a flat coil, the loss of heating surface presented towards the premises to be heated, compared to the rectangular surface in which the device is fitted, is minimised.
[0002] BACKGROUND OF THE INVENTION Heating premises using electrical energy essentially uses the Joule effect in an electrical resistive element powered by electrical connectors from an electrical energy source. The transfer of heat to the premises, the air and the occupants occurs by thermal conduction and / or convection and / or infrared radiation emitted by the electrical resistive element due to its temperature.
[0003] The electrical resistive element may be in the form of a winding (coil) of a resistive strip on a core, for example made of ceramic. The core may be, for example, cylindrical in shape with a director in the form of a circle or a very flattened ellipse or a polygon with rounded corners. The core can be a solid solid body or a hollow body, generally the resistive element has proximity and / or extensive contact with the mass of the core The core may be structured, comprising for example at its periphery longitudinal beams distributed radially regularly at the vertices of a regular polygon, thus allowing support of the strip by means of the contact of the strip with the beams and the absence of contact of the strip with the core in the inter-beam spaces. The resistive strip may be, for example, but not limited to, rectangular in section. An example of a heating tape winding is a stainless steel or aluminum alloy tape winding where the width of the tape is between 25mm and 50mm typically having the value of 30mm and where its thickness is between 15micrometers and 100micrometers typically having the value of 20micrometers at 35mm pitch. Another example of a heating tape winding is a tape made of polymeric material such as polypropylene or PET or Teflon 50micrometers thick and 25mm wide aluminized on at least one of its faces to a thickness of 5micrometers.
[0004] We are preferably considering here flat cores which are capable of allowing a large surface area of ribbon capable of emitting heat. The shape of the cores is therefore preferably oblong so that the winding has in its lower part a radiating surface of large extension while keeping a limited vertical dimension.
[0005] In an exemplary embodiment known as a parallelepiped shape with rounded ends, each turn is inscribed on a volume consisting of a rectangular parallelepiped volume of large horizontal extension and much lower vertical height, two of the opposite vertical faces of which are each adjoining a semi-cylindrical volume of diameter equal to the height of said face.
[0006] In another embodiment, each turn is inscribed on an ellipsoid with a major horizontal axis much larger than the minor vertical axis; for example, the major axis is ten times larger than the minor axis. Generally speaking, such a core can be conventionally described as consisting of three parts a central part called the longitudinal part of oblong shape, that is to say of length greater than the thickness, and potentially concave over at least a fraction of its length two end parts, called uprights, cylindrical and convex with a rounded and flat section facing the rounding, The three parts can be part of a monolithic whole or assembled together.
[0007] Winding the ribbon on such a core with smooth, i.e. unstructured, cylindrical uprights (103) implies that the ribbon has a rectilinear trajectory but is inclined at an angle alpha in the longitudinal part or the angle alpha is equal to the angle of the half helix that the ribbon travels when turning around the upright. The angle alpha must satisfy the condition that at the end of the movement along a full turn the variation in position along Z, axis of the uprights, is equal to the winding pitch p, i.e. the width of the ribbon plus the desired distance margin between two turns. Therefore the surface presented by the ribbon on one of the faces of the device and therefore the heating surface, let us agree that it is the front, is inscribed in a trapezoid with two of the opposite sides inclined at the angle alpha. However, it is desirable to inscribe the heating coil device in a rectangle or square to be able to assemble several of them in paving, of the ceiling for example.
[0008] The very simple calculation shows that alpha=Atan(p / (2*pi*r+2L) where L is the length of the longitudinal part and r the radius of the rounded part of the amount
[0009] For example, for: p=6 cm -L=60cm, alpha=2.75 degrees Therefore, compared to this rectangular surface, we lose the surface of two right triangles with a small side equal to half the pitch of the coil and a large side equal to the length of the longitudinal part. This loss is all the more significant as the width of the ribbon increases.
[0010] Furthermore, there is another source of heating surface loss which is the distance required between the turns of ribbon to avoid short circuits. This loss is all the more significant as the ratio between the inter-turn distance relative to the width of the turns is high and all the more significant as the number of turns is high. What has been said for the front is strictly identical for the back. This appears clearly in [Fig.l]. It should be noted, however, that the two sides do not play the same role since one is a priori oriented towards the room to be heated, the other not.
[0011] DETAILED DESCRIPTION OF THE INVENTION The device which is the subject of the invention presented below makes it possible to heat a room in particular by infrared radiation while avoiding the aforementioned drawback in the sense that it makes it possible to create a large heating surface, while minimizing the losses of heating surface compared to the rectangular surface in which the device fits. By convention, the front side is the side facing the room to be heated. It is therefore this side whose heating surface it is important to optimize. The device which is the subject of the invention is characterized in that the uprights are not smooth as in the prior art but structured so as to present a series of sections following one another where each section:
[0012] - comprises a rounded cylindrical or truncated cone-shaped part around which the ribbon makes a U-turn - has a height equal to p - whose axis is inclined in a plane parallel to the longitudinal part of the angle al-phaprime relative to the general axis of the amount. The sections of one amount correspond to those of the other amount through a simple translation. It is easy to obtain the following result: p= sin(alphaprime)* 2*pi*r+tan(2*alphaprime)*L or to the first order: p= alphaprime* 2*pi*r+2*alphaprime*L, or alphaprime =p / (2*pi*r+2*L)
[0013] To the nearest first order the angle alphaprime is equal to the angle alpha which defines the angle of inclination of the longitudinal parts of the turns in the prior art with smooth uprights. To be more precise, the value of alphaprime can be found numerically. When the choice is made of a rounded cylindrical part, the portions of ribbon in the longitudinal part of the front face are perpendicular to the general axis of the uprights, are located in the same plane, and all of the portions of ribbon in the front face are inscribed in a rectangle (and not in a trapezoid as in the art prior) which eliminates the surface loss triangles existing in the prior art.
[0014] However, the loss of surface area due to the necessary spacing between each turn still exists, because the longitudinal parts being coplanar it is necessary to maintain a distance between them in this plane.
[0015] Correlatively, the portions of ribbon in the longitudinal part of the reverse face are inclined by the angle 2*alphaprime and therefore all of the portions of ribbon in the reverse face are inscribed in a trapezium which generates two right triangles of loss of small side equal to the pitch of the turn and large side equal to the length of the longitudinal part.
[0016] The choice of a truncated cone shape for the rounded part makes it possible to reduce and even eliminate the loss of heating surface due to the spacing between turns. In fact, the longitudinal parts of the turns of the front face are always perpendicular to the general axis of the uprights, but are no longer coplanar because they are inclined at the same angle as the angle of the truncated cone. The spacing between turns then results from the vertical component of the distance existing between the upper edge of one turn and the lower edge of the next turn. This is illustrated by the drawings in FIG.
[0017] By combining the alphaprime angle inclination and the truncated cone shape of the rounded parts, the ultimate optimization of the heating surface of the front is obtained.
[0018] BRIEF DESCRIPTION OF THE DRAWINGS Other objects, characteristics and advantages of the invention will be better understood in light of the detailed description which follows, with reference to the appended drawings in which:
[0019] [Fig.l] represents an exemplary embodiment of the state of the art. A smooth upright (103) is shown isolated. The wound ribbon (101) is shown in front and back views inside the rectangular frame (102) which is present to visualize the geometries. On each of the front and back views we can see the two triangles (1011) of surface loss.
[0020] [Fig.2A] and [Fig.2B] relate to an embodiment where the angle alpha is 5 degrees.
[0021] [Fig.2A] shows two views of the core (202) with the two uprights (203). [[Fig.2B]] shows views relating to the same embodiment of the invention where the angle alpha is 5 degrees. There we see a double-sided presentation of the ribbon (201) wound on the core with its two uprights in the frame (204) intended to allow good visualization of the geometries. We see the two surface loss triangles (2011) on the reverse side; we note the absence of surface loss triangles on the front side.
[0022] [Fig.3A] and [Fig.3B] relate to an embodiment where the sections constituting the amounts are truncated cone-shaped.
[0023] [Fig.3A] shows an upright (303) assembled from frustoconical sections (304) on a tube (305). [Fig.3B] shows the ribbon (301) as in this embodiment where the sections constituting the uprights are of truncated cone shape. We see the slight superposition (3015) without contact between two consecutive turns.
Claims
Claims
1. An electric heating device consisting of at least one single-layer three-dimensional p-p pitch winding of an electrical resistive ribbon on a core having a longitudinal central portion and two uprights where the uprights are structured and are composed of a plurality of sections having a rounded portion around which the ribbon makes a half-turn at a height equal to p whose axis is inclined in a plane parallel to the longitudinal portion at an angle alpha relative to the general axis of the upright
2. Claim according to 1 the angle alpha is defined by the relation alpha=Atan(p / (2*pi*r+2L) where L is the length of the longitudinal part and r the radius of the rounded part of the upright
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6. Claim according to 1 and 2 where the rounded part is cylindrical Claim according to 1 and 2 where the rounded part is frustoconical Claim according to 1 to 4 where the uprights are monolithic Claim according to 1 to 4 where the uprights are made up of an assembly of sections.
7. Claim according to 6 where the sections are assembled on a tube or axis common to all the sections.
8. Claim according to 1 to 7 wherein the ribbon is made of aluminum alloy or iron alloy or aluminized polymeric material.
9. Claim according to 1 to 8 where the width of the tape is between 25mm and 50mm and where its thickness is between 15 micrometers and 100 micrometers.