Patent Application
20220082297
This disclosure refers to a flow heater of the type generally known from DE 10 2017 121 341 B4.
Flow heaters are needed, for example, in automobiles to heat various liquids, in particular water or aqueous solutions. Constant objectives in the development of flow heaters for automobiles are a compact design, low manufacturing costs, and a high efficiency, such that a large amount of liquid can be heated in a short time.
This disclosure teaches a flow heater that achieves these objectives to an even greater extent.
In a flow heater according to this disclosure, a corrugated sheet is attached to a metal plate that carries an electrical heating resistor, for example a resistive layer, the ridges of which plate protrude into a flow channel of the liquid that is to be heated. The corrugated sheet has openings, through which the liquid that is to be heated can pass. The liquid that is to be heated therefore flows in the flow channel, both between the metal plate and the corrugated sheet, that is to say, within the ridges of the corrugated sheet, and also on the side of the corrugated sheet facing away from the metal plate, i.e., in the furrows of the corrugated sheet. In this way, the heat removal from the metal plate can be significantly improved, and thus a greater efficiency with a higher power density can be achieved.
The openings in the corrugated sheet allow an interchange between the liquid below and above the corrugated sheet. In addition, in the event of overheating, the openings prevent water vapor from accumulating under a ridge of the corrugated sheet. This is advantageous as water vapor would thermally insulate the metal plate from the liquid to be heated.
The corrugated sheet may have a sinusoidal cross-section. In other embodiments, the corrugated sheet may have an angular cross-section in which the ridges have flat side walls that extend from a flat furrow. In this way, a good thermal coupling of the corrugated sheet to the metal plate can be achieved in the furrows.
In an advantageous development, provision is made for the metal plate to be made of steel and the corrugated sheet to be made of an aluminium-based alloy, that is to say, an alloy that contains predominantly aluminium, for example, of at least 80% aluminium by weight, or more. The corrugated sheet can, for example, be attached to the metal plate by means of brazing. Openings in the corrugated sheet increase its flexibility, so that mechanical stresses that may arise in the course of temperature alterations, on account of different thermal expansion coefficients, can be compensated for more easily.
In a further advantageous refinement, provision is made for the openings to be arranged in the peaks of the ridges facing away from the metal plate. In the event of overheating, water vapor can in this way be removed from the metal plate particularly rapidly.
In a further advantageous refinement, provision is made for the density of the openings in an initial section of the flow channel to be greater than in a central section of the flow channel. When liquid that is to be heated reaches the metal plate, it can then divide particularly rapidly into one part flowing between the metal plate and the corrugated sheet, that is to say, within the ridges, and one part flowing along the part of the corrugated sheet facing away from the metal plate, that is to say, in the furrows. In a central section of the flow channel, on the other hand, a lower openings density is advantageous, for example an openings density that is only half as large, or less. Here the openings density is understood to be the quotient of the surface area of the openings and the total surface area.
In a further advantageous refinement, provision is made for the density of the openings in an end section of the flow channel to be greater than in a central section of the flow channel. In this way, the two component flows of liquid, flowing above and below the corrugated sheet, can be rapidly and efficiently recombined.
In a further advantageous refinement, provision is made for the density of the openings in an initial section of the flow channel to be greater than that in a central section of the flow channel.
The above-mentioned aspects of exemplary embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:
The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.
The flow heater shown in
The flow channel runs along a metal plate 6, which carries one or a plurality of electrical heating resistors, for example in the form of conductive tracks. In order to improve heat dissipation to the liquid in the flow channel, the metal plate 6 carries at least one corrugated sheet 7, which protrudes into the flow channel.
In the example of embodiment shown, the flow channel has a U-shaped profile. The density of the openings is increased at both ends of the flow channel.
In the embodiment shown, all openings 8 have the same size within manufacturing tolerances. However, it is also possible to achieve an increased openings density in the initial section 9a, and/or the end section 9b, by using larger openings instead of increasing their number per unit surface area. In the initial section 9a and the end section 9b, the distance between openings 8 may be smaller than the width of the openings 8, measured in the longitudinal direction of the corrugations. In the central section 9c, the distance between openings 8 is larger than the width of the openings 8, measured in the longitudinal direction of the corrugations.
The openings 8 are in each case arranged in the peaks of the ridges of the corrugations facing away from the metal plate 6. In this way, any gas bubbles can escape particularly rapidly from the spaces between the metal plate 6 and the corrugated sheets 7. Each ridge of the corrugations has a plurality of openings 8.
The metal plate 6 is, for example, a steel sheet. The corrugated sheets 7 can, for example, be made of an aluminium-based alloy, and brazed to the metal plate 6. In order not to weaken the bonding between the metal plate 6 and the corrugated sheet 7, the furrows of the corrugated sheets adjacent to the metal plate 6 are free of openings.
While exemplary embodiments have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 123 996.3 | Sep 2020 | DE | national |
This application claims priority to DE 10 2020 123 996.3, filed Sep. 15, 2020, the entire disclosure of which is hereby incorporated herein by reference.
