Flow heater with corrugations

Abstract

A flow heater is described, having a housing (1) and a metal plate (6); a flow channel extends in the housing (1) from a liquid inlet (2) to a liquid outlet (3); the metal plate (6) carries an electric heating resistor, and the flow channel extends along the metal plate (6). According to the invention, it is provided that the metal plate (6) carries a corrugated sheet (7) which projects into the flow channel, and has openings (8) through which the liquid to be heated can pass.

Description

Technical Field

[0001] This invention relates to a flow heater. A flow heater having the features described in the preamble of claim 1 is known from DE10 2017 121 341 B4. Background Technology

[0002] Flow heaters are needed, for example, in automobiles, to heat various liquids, especially water or aqueous solutions. The consistent goals in the development of automotive flow heaters have been compact design, low manufacturing costs, and high efficiency, enabling the heating of large quantities of liquid in a short time. Summary of the Invention

[0003] The purpose of this invention is to achieve these objectives to a greater extent.

[0004] This objective is achieved by the flow heater according to claim 1. Advantageous improvements of the invention are the subject of the dependent claims.

[0005] In the flow heater of the present invention, a corrugated sheet is attached to a metal plate that carries an electric heating resistor (e.g., a resistive layer), the ridges of which protrude into a flow channel for the liquid to be heated. The corrugated sheet has openings through which the liquid to be heated can pass. Therefore, the liquid to be heated flows in the flow channel, i.e., between the metal plate and the corrugated sheet (that is, within the ridges of the corrugated sheet), and also on the sides of the corrugated sheet away from the metal plate (i.e., in the grooves of the corrugated sheet). In this way, heat dissipation from the metal plate can be significantly improved, thereby achieving higher efficiency and higher power density.

[0006] The openings in the corrugated sheet allow for the exchange of liquids between the liquids below and above the sheet. Furthermore, in cases of overheating, the openings prevent water vapor from accumulating beneath the ridges of the corrugated sheet. This is advantageous because the water vapor will thermally insulate the metal sheet from the liquid being heated.

[0007] The corrugated sheet may have a sinusoidal cross-section. In other embodiments of the invention, the corrugated sheet may have an angular cross-section, wherein the ridges have flat sidewalls extending from flat grooves. This allows for good thermal coupling between the corrugated sheet and the metal plate within the grooves.

[0008] In an advantageous improvement of the invention, the metal plate is specified to be made of steel and the corrugated sheet to be made of an aluminum-based alloy (that is, an alloy mainly composed of, for example, at least 80% by weight or more, aluminum). For example, the corrugated sheet can be attached to the metal plate by brazing. The openings in the corrugated sheet increase its flexibility, thereby making it easier to compensate for mechanical stresses that may arise during temperature changes due to different coefficients of thermal expansion.

[0009] In another advantageous improvement of the invention, an opening is provided in the peak of the ridge opposite to the metal plate. In the event of overheating, water vapor can be removed from the metal plate particularly rapidly in this manner.

[0010] In another advantageous improvement of the invention, the opening density in the initial section of the flow channel is specified to be greater than the opening density in the central section of the flow channel. When the liquid to be heated reaches the metal plate, it can be particularly quickly divided into a portion flowing between the metal plate and the corrugated sheet (i.e., flowing within the ridges), and a portion flowing along the portion of the corrugated sheet away from the metal plate (i.e., flowing in the grooves). In the central section of the flow channel, a lower opening density is advantageous, for example, an opening density of only half or less. Here, opening density is understood as the quotient of the opening surface area and the total surface area.

[0011] In another advantageous improvement of the invention, the opening density in the end sections of the flow channel is specified to be greater than the opening density in the central section of the flow channel. This allows the two component flows of the liquid flowing above and below the corrugated sheet to be rapidly and efficiently recombined.

[0012] In another advantageous improvement of the invention, the opening density in the initial section of the flow channel is specified to be greater than the opening density in the central section of the flow channel. Attached Figure Description

[0013] Referring to the accompanying drawings, other details and advantages of the invention will be explained through examples of embodiments. Wherein:

[0014] Figure 1 An example of a transient liquid heater is shown;

[0015] Figure 2 It shows Figure 1 sectional view; and

[0016] Figure 3 An example of a heating plate for a transient liquid heater is shown. Detailed Implementation

[0017] Figure 1 and Figure 2 The flow heater shown has a housing 1, which has an inlet 2 and an outlet 3, as well as electrical connectors 4 and 5. A flow channel for the liquid to be heated extends from the inlet 2 to the outlet 3 in the housing 1.

[0018] A flow channel extends along a metal plate 6, which carries one or more electrically heated resistors, for example, in the form of conductive rails. To improve heat dissipation for the liquid in the flow channel, the metal plate 6 carries at least one corrugated sheet 7 that protrudes into the flow channel.

[0019] Figure 3 An example of such a metal plate 6 having a corrugated sheet 7 is shown. It can be seen that the corrugated sheet 7 has a plurality of openings 8 through which the liquid to be heated can pass. In the flow channel, the liquid to be heated thus flows between the metal plate 6 and the corrugated sheet (i.e., below the ridges of the corrugations), and also flows on the sides of the corrugations away from the metal plate 6 (i.e., in the grooves of the corrugations). Here, in the event of overheating, the openings 8 also prevent water vapor from accumulating below the ridges of the corrugated sheet 7, thereby thermally insulating the metal plate 6.

[0020] In the example of the illustrated embodiment, the flow channel has a U-shaped profile. The density of the openings increases at both ends of the flow channel. Figure 3 Correspondingly, the initial section 9a and the end section 9b of the flow channel are shown, wherein the density of openings is increased compared to the opening density of the central section 9c. The increased opening density of the initial section 9a makes it easier to divide the liquid flow entering the flow channel into one flow component flowing between the metal plate 6 and the corrugated sheet 7 and another flow component flowing on the side of the corrugated sheet 7 away from the metal plate 6. In a similar manner, the increased opening density of the end section 9b makes it easier to combine the two flow components. In the central section 9c, several openings 8 are sufficient to prevent any bubbles that may form from accumulating between the metal plate 6 and the corrugated sheet 7.

[0021] In the illustrated embodiment, all openings 8 have the same dimensions within manufacturing tolerances. However, an increased opening density can also be achieved in the initial segment 9a and / or the end segment 9b by utilizing larger openings rather than increasing their number per unit surface area. In the initial segment 9a and the end segment 9b, the distance between the openings 8 may be less than the width of the opening 8, measured in the longitudinal direction of the corrugated portion. In the central segment 9c, the distance between the openings 8 is greater than the width of the opening 8, measured in the longitudinal direction of the corrugated portion.

[0022] In each case, the openings 8 are arranged in the peaks of the ridges of the corrugated portion opposite to the metal plate 6. This allows any air bubbles to escape particularly quickly from the space between the metal plate 6 and the corrugated sheet 7. Each ridge of the corrugated portion has multiple openings 8.

[0023] The metal plate 6 is, for example, a steel sheet. The corrugated sheet 7 may be made of, for example, an aluminum-based alloy and brazed to the metal plate 6. In order not to weaken the bond between the metal plate 6 and the corrugated sheet 7, the grooves of the corrugated sheet adjacent to the metal plate 6 do not have openings.

[0024] List of icon numbers

[0025] 1. Outer shell

[0026] 2 entrances

[0027] 3. Exports

[0028] 4 Connectors

[0029] 5 connectors

[0030] 6 metal plates

[0031] 7 Corrugated Sheets

[0032] 8 Openings

[0033] 9a Initial Section

[0034] 9b End section

[0035] 9c Central section.

Claims

1. A flow heater, comprising: The outer casing (1), wherein the flow channel extends from the inlet (2) to the outlet (3), and A metal plate (6) carries an electric heating resistor, and the flow channel extends along the metal plate (6). Its features are, The metal plate (6) supports the corrugated sheet (7) and has an opening (8) in which the corrugated sheet (7) protrudes into the flow channel, through which the liquid to be heated can pass. The metal plate (6) is made of steel, and the corrugated sheet (7) is made of aluminum-based alloy and brazed to the metal plate (6). The electric heating resistor is in the form of a conductive rail; The density of the openings (8) in the initial section (9a) of the flow channel is greater than the density of the openings in the central section (9c) of the flow channel.

2. The flow heater according to claim 1, characterized in that, The opening (8) is formed at the peak of the ridge of the corrugated sheet (7), away from the metal plate (6).

3. The flow heater according to claim 1, characterized in that, Each ridge of the corrugated sheet (7) has at least one opening (8).

4. The flow heater according to claim 1, characterized in that, The density of the openings (8) in the end section (9b) of the flow channel is higher than the density of the openings in the central section (9c) of the flow channel.

5. The flow heater according to claim 1, characterized in that, In the initial section (9a) and / or end section (9b) of the flow channel, the width of the opening (8) cut into the ridge of the corrugated sheet (7) is greater than the distance from the edge of one opening (8) to an adjacent opening (8) on the same ridge, the width being measured in the longitudinal direction of the ridge.

6. The flow heater according to claim 1, characterized in that, The grooves of the corrugated sheet (7) adjacent to the metal plate (6) do not contain openings (8).

7. The flow heater according to claim 1, characterized in that, The metal plate (6) supports multiple corrugated sheets (7).

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