EP2614764A2 - Waste water heat exchanger for a dishwasher and dishwasher - Google Patents

Abstract

The heat exchanger has channel forming plates (102,104,106,108) that are made of plastic material. The side open channels (322,324,326,342,344,346) are placed on side of channel forming plates and provided with outlet opening and inlet opening. The heat transfer plates (203,205,207) are made of metallic material, or thermally conductive plastic. The channel forming plates and heat transfer plates are arranged such that open side of channel is arranged opposite to open side of another channel, and open sides of channels are closed by heat transfer plate.

Description

The present invention relates to a waste water heat exchanger for dishwashers, in particular for commercial dishwashers, and a dishwasher with such a waste water heat exchanger.

When operating dishwashers, rinsing water for dishwashing must be heated, while at the same time heated waste water is being removed so that it is either disposed of or treated.

It is therefore known to use heat exchangers in dishwashers, s. for example the EP 0 689 791 A1 , It is an object of the present invention to provide an improved wastewater heat exchanger and a dishwasher with an improved wastewater heat exchanger.

This object is achieved by a waste heat exchanger for dishwashers according to claim 1 and a dishwasher with such a waste water heat exchanger according to claim 9. Claims 2 to 8 each relate to advantageous embodiments of the wastewater heat exchanger according to the invention for dishwashers.

According to the invention, the wastewater heat exchanger comprises at least two channel molding plates and at least one heat transfer plate. The at least two channel molding plates are made of a plastic material, while the heat transfer plate of a metallic material or a thermally conductive plastic material, in particular a plastic, the additives, in particular metallic additives, are added. A thermally conductive plastic or a plastic with increased thermal conductivity in the context of this invention comprises in particular plastics with a thermal conductivity of 1.0 W / (m * K) to 10 W / (m * k), preferably plastics with thermal conductivities of 5.0 W / (m * K) to 10 W / (m * K).

In the case of a plastic with increased thermal conductivity, preference is given to using PP (polypropylene). The thermal conductivity of PP, PA (polyamide) or similar plastics is normally about 0.2 W / (m * K). By additives, such as aluminum oxide, magnesium oxide, graphite, aluminum nitride or boron nitride, significantly higher values can be achieved. An additive is added to the plastic granules prior to processing (spraying). Thermal conductivities of 1, 0 (W / (m * K) to 10 W / (m * K) are achieved, which means an increase of the thermal conductivity by a factor of 5 to 50 compared to normal PP.

The term "metallic material" for the purposes of this invention includes all metals, semimetals and alloys and intermetallic phases, as well as materials that undergo a metallic bond. Such materials are characterized by a high thermal conductivity.

The term "plastic material" includes, inter alia, materials whose basic component is synthetically or semi-synthetically prepared from monomeric organic molecules.

The term plastic material in the context of this invention includes in particular thermoplastics, thermosets, elastomers and thermoplastic elastomers.

A channel molding plate has on at least one side of the channel molding plate on one side open, in particular continuously extending channel, which preferably extends from an outer region or edge region of the channel molding plate in an inner region and from there again in an outer region or edge region of the channel molding plate. The channel has an inlet opening at one end and an outlet opening at its other end, so that a flowable medium, in particular fresh water on the one hand and sewage on the other hand, can be introduced into the channel at the inlet opening, through the channel and through the outlet opening can be discharged again.

Depending on the structure of the wastewater heat exchanger duct plates are used, which form a channel only on one side, or channel molding plates, which form a channel on both sides. Channel molding plates, which form a channel on both sides, are used in particular when a larger-sized wastewater heat exchanger is required, these channel molding plates are then used in an inner region of the wastewater heat exchanger or as intermediate plates. Channel molding plates with a channel on only one side are used as so-called end plates, which include the above-mentioned intermediate plates in a sandwich construction, especially in smaller-dimensioned wastewater heat exchangers or even larger-sized wastewater heat exchangers.

The channel molding plates and the heat transfer plate (s) are arranged such that the open side of a channel of a first channel molding plate faces the open side of a channel of a second thermoforming plate, the open side of the two channels being disposed through a heat transfer plate disposed between the two channel molding plates is, are separated from each other. The open on one side channels of the channel molding plates are therefore completed by the heat transfer plate.

By a wastewater heat exchanger according to the present invention, therefore, two channels are realized, a channel for a first fluid, typically fresh water, and a channel for a second fluid, typically wastewater, these two channels being very close to each other and these two channels passing through the heat transfer plate , which is very good thermal conductivity, are separated from each other.

The wastewater heat exchanger of the present invention has the particular advantage that it can be made very cost-effective, on the other hand, it has the advantage that the channel molding plates on the one hand and the heat transfer plate or the heat transfer plates on the other hand, both in terms of their structure and in terms of their Material selection can be optimally adapted to their desired function.

The channel molding plates form the structures that are required for the formation of the channels, and they must therefore have a certain dimensional stability and thus a certain material thickness. The channel molding plates are therefore made according to the invention of plastic, since it is a relatively light material in plastic, even at thicker wall thicknesses, cost, preferably by injection molding, can be produced without the total weight is too large, while the thermal conductivity due the structure of the invention need not be considered.

On the other hand, the heat transfer plate or the heat transfer plates made of a metallic material or a thermally conductive plastic or a plastic with increased thermal conductivity, in particular a plastic with metallic additives, so that a very high thermal conductivity is provided. This is particularly advantageous because heat transfer from one channel to another channel occurs through this heat transfer plate and only to a lesser extent through the channel die plates which, due to their plastic material and the required thickness of the material to provide the dimensional stability noted above, have lower thermal conductivity exhibit.

Since, due to the structure and construction of the waste heat exchanger according to the present invention, the heat transfer plates need not have any inherent dimensional stability, but merely constitute a separating layer between the channels formed by the channel molding plates, these heat transfer plates can be made very thin, so that both costs As well as weight are minimized, at the same time a maximum thermal conductivity and thus a maximum efficiency of the heat exchanger is provided.

The particular structure and construction of the wastewater heat exchanger according to the invention therefore lead to optimal results in terms of the exchange of heat between two fluids, wastewater and fresh water, at the same time costs and weight are kept very low.

In a preferred embodiment, the channel molding plates are formed so that a substantially spiral-shaped channel is formed, wherein the spiral shape may be formed nearly circular, but may also have a more straight or oval shape. It is particularly preferred to change the curvature of the spiral as evenly as possible and in particular to provide no edges or corners in the channels, as this may hinder the flow of fluids, wastewater and fresh water. The shape of the spiral channels, as a double spiral, can be adapted in particular to the cross-sectional shape of the channel plate or the heat transfer plates, both substantially circular or oval channel plates and heat transfer plates can be provided, or even rectangular cross-sectional shapes can be provided, in particular with rounded Corners. The overall shape of the wastewater heat exchanger can be adapted in many areas to the requirements of the dishwasher.

A particularly preferred wastewater heat exchanger comprises two channel molding plates which form a channel on its two sides, that is to say on the front side and the rear side, and two channel molding plates which form a channel on only one side. Furthermore, such a particularly preferred wastewater heat exchanger comprises a total of three heat transfer plates.

The channel molding plates and the heat transfer plates are arranged so that a total of three pairs of opposing channels are formed, wherein the opposite channels of each pair are separated by a heat transfer plate.

As a result, a multi-layer waste heat exchanger is realized, so that the effective total length of the channel or channels through which the fresh water on the one hand and the wastewater flows on the other hand is extended, so that a total of higher heat exchange performance is realized.

The channel molding plates and the heat transfer plates are arranged so that a fluid first passes through a channel in a first channel plate shape, then a channel in a second channel plate and finally a channel in a third channel plate form, for both fluids, so the waste water and the fresh water , applies.

Alternatively, it is also possible to provide a waste water heat exchanger with only one channel molding plate, which forms a channel on both sides, and two channel molding plates, which form a channel only on one side. Further, it is also possible to provide waste heat exchangers having three or more channel molding plates which form a channel on both sides to further increase the heat exchange performance of the wastewater heat exchanger.

The wastewater heat exchanger of the present invention is therefore modular in design and, with very few, different components, can be adapted or extended very flexibly, which is a further advantage of the wastewater heat exchanger according to the present invention.

However, it is crucial in the modular structure that basically two different types of components, preferably of two different materials, are present, namely on the one hand the channel molding plates made of plastic, which in particular dictate the dimensional stability and structure and are stable enough to hold this structure, and on the other hand, the heat transfer plates, which are made of metal or a plastic with increased thermal conductivity and which can be made very thin, to allow maximum heat transfer, without special structural claims are made of these heat transfer plates. The advantages described above are not attainable with a heat exchanger, even with a plate heat exchanger, which is composed essentially of identical components.

In particular, it should be noted that in the wastewater heat exchanger according to the present invention, regardless of the dimensioning, ie regardless of whether only two channel molding plates and a heat transfer plate or more channel molding plates and more heat transfer plates are used, the heat transfer plate or the heat transfer plates always in an interior are arranged, so basically surrounded on both sides of channel molding plates, which give a necessary shape structure and protect the heat transfer plates from possible shocks and damage from the outside.

In a preferred embodiment, the channel molding plates and the heat transfer plates are glued together, in particular pressed and glued, which allows a particularly simple and therefore cost-effective production. Also, the plates can, for example, be welded, if all plates are made of plastic.

The channel molding plates are preferably produced in an injection molding process, wherein as a material in particular polypropylene (PP), polyamide (PA) or similar materials are suitable. Suitable materials for the heat transfer plates are materials with higher conductivity than PP or PA, in particular copper, stainless steel or plastics with conductivity-increasing additives, which have a very high thermal conductivity, or even alloys.

Due to the advantageous structure of the wastewater heat exchanger according to the invention, the heat transfer plates can be made very thin, preferably the heat transfer plates have a thickness of 0.1 mm to 1.5 mm, more preferably from 0.2 mm to 0.8 mm, further preferably 0.4 mm to 0.6 mm and in particular from 0.2 mm to 0.4 mm.

The invention further relates to a dishwasher, in particular a commercial dishwasher, with a waste water heat exchanger, as has been described above.

Fig. 1

eine perspektivische Ansicht einer Ausführungsform eines erfindungsgemäßen Abwasserwärmetauschers;

Fig. 2

eine teilweise geschnittene, perspektivische Ansicht der in Fig. 1 gezeigten Ausführungsform des Abwassertauschers gemäß der vorliegenden Erfindung;

Fig. 3

eine perspektivische Ansicht einer Ausführungsform einer Wärmeübergangsplatte, wie sie in einem Abwasserwärmetauscher gemäß der vorliegenden Erfindung eingesetzt werden kann;

Fig. 4

eine Ausführungsform einer Kanalformplatte, wie sie in einem erfindungsgemäßen Abwasserwärmetauscher eingesetzt werden kann;

Fig. 5

eine weitere Ausführungsform einer Kanalformplatte, wie sie in einem erfindungsgemäßen Abwasserwärmetauscher, beispielsweise in der in den Fig. 1 und 2 gezeigten Ausführungsform, eingesetzt werden kann.

These and other advantages and features of the invention will become more apparent from the particular embodiment shown below. Show it:

Fig. 1

a perspective view of an embodiment of a wastewater heat exchanger according to the invention;

Fig. 2

a partially sectioned, perspective view of the in Fig. 1 shown embodiment of the wastewater exchanger according to the present invention;

Fig. 3

a perspective view of an embodiment of a heat transfer plate, as it can be used in a wastewater heat exchanger according to the present invention;

Fig. 4

an embodiment of a channel molding plate, as it can be used in a wastewater heat exchanger according to the invention;

Fig. 5

a further embodiment of a channel molding plate, as used in a wastewater heat exchanger according to the invention, for example in the in the Fig. 1 and 2 shown embodiment, can be used.

Fig. 1 shows a perspective view of an embodiment of a wastewater heat exchanger 10 according to the invention, comprising a total of four channel molding plates 102, 104, 106 and 108. Between the channel molding plates 102, 104, 106 and 108 a total of three heat transfer plates 203, 205 and 207 are arranged, the heat transfer plate 203 between the channel molding plates 102 and 104, the heat transfer plate 205 between the channel molding plates 104 and 106, and the heat transfer plate 207 between the channel molding plates 106 and 108th

As in particular in the Fig. 2 . 4 and 5 As can be seen, the channel molding plates 102, 104, 106 and 108 are shaped to form a one-side open channel extending continuously and substantially spirally from an outer region or edge region of the channel molding plate 102, 104, 106, 108 into an interior region and from there again into an outer region or edge region of the channel molding plate 102, 104, 106, 108 extends.

The open sides of the channels are closed by the heat transfer plates 203, 205 and 207, so that closed channels arise.

The wastewater heat exchanger 10 has an inlet opening F1 for the introduction of fresh water. The fresh water introduced through the inlet port F1 is first led into the channel 322 formed by the channel forming plate 106 and the heat transfer plate 207. The fresh water then flows through the channel 324 formed by the channel molding plate 104 and the heat transfer plate 205. Finally, the fresh water is passed through the channel 326, which is formed by the channel plate 102 and the heat transfer plate 203. The fresh water is finally removed again at an outlet opening F2.

Further, the waste water heat exchanger 10 includes an inlet port A1 for the waste water. The waste water first flows through the channel 342 formed by the channel forming plate 104 and the heat transfer plate 203, subsequently through the channel 344 formed by the channel forming plate 106 and the heat transfer plate 205, and finally through the channel 346 passing through the channel forming plate 108 and the heat transfer plate 207 is formed. The wastewater is removed at an outlet A2 the wastewater heat exchanger.

The channel molding plates 102, 104, 106 and 108 and the heat transfer plates 203, 205 and 207 and the inlets A1, F1 and the outlets A2, F2 are designed so that wastewater and fresh water in opposite channels in opposite directions and in directly adjacent Run channels and wastewater and fresh water and the entire wastewater heat exchanger in opposite directions, through the different levels of the channels, ie also in the vertical direction V (s. Fig. 1 ), so that fresh water, which has just been introduced through the inlet F1, flows in a channel region 322 which opposes a channel region 346 in which Wastewater is located, which has already passed through almost the entire wastewater heat exchanger. The same applies vice versa for wastewater that is being led through the inlet A1 into the wastewater heat exchanger.

The channel molding plates 102, 104, 106 and 108 are made of PP or PA in this embodiment, while the heat transfer plates 203, 205 and 207 are made of plastic in this embodiment, wherein the plastic is provided with additives that increase the thermal conductivity. Alternatively, the heat transfer plates can also be made of metal, for example, copper.

Fig. 3 shows an embodiment of a heat transfer plate 200, which is formed very similar to the heat transfer plates, which in the Figures 1 and 2 Therefore, identical reference numerals are used for these similar elements. At the in Fig. 3 shown heat transfer plate 200 is a heat transfer plate made of stainless steel, which has a thickness of 0.3 mm. Again, it is of course possible that alternatively a heat transfer plate made of plastic with thermal conductivity increasing additives is used.

How clearly in Fig. 3 As can be seen, the heat transfer plate 200 has two openings 220 and 240, can pass through the wastewater or fresh water to pass through all the channel formed by the channel molding plates and the heat transfer plates channel or channels of the wastewater heat exchanger.

Fig. 4 shows an embodiment of a channel molding plate 104, which in the Figures 1 and 2 shown channel molding plate 104 is very similar, so that identical reference numerals are used. At the in Fig. 4 Channel plate shown is a mold plate, which forms on both sides each one open on one side channel, wherein in the perspective view of Fig. 4 only the channel 342 is visible on one side. In the Fig. 4 shown channel molding plate 104 is therefore a channel molding plate, which in a multi-layer wastewater heat exchanger, such as in Fig. 1 and Fig. 2 is shown, and is used there in an indoor area.

Fig. 5 shows a perspective view of another channel molding plate 108, which in the Figs. 1 and 2 shown channel plate 108 is very similar and can also be used in a multi-layer wastewater heat exchanger.

At the in Fig. 5 illustrated embodiment of a channel molding plate 108 is such a channel molding plate, in which only one side of a channel 346 is formed.

In the Fig. 5 illustrated embodiment of the channel plate 108 is therefore suitable both for a multi-layer wastewater heat exchanger, as in the Fig. 1 and 2 is shown, in this case, for a channel molding plate, which is used in a peripheral region of the waste water heat exchanger as the end plate, also suitable in Fig. 5 also shown channel plate for a smaller wastewater heat exchanger, for example, consists of only two channel plates, which are separated by a heat transfer plate.

Will the in the Fig. 4 and 5 illustrated embodiments of the channel molding plates 104 and 108 used in a wastewater heat exchanger, as shown in the Fig. 1 and 2 is shown, serve in the Fig. 4 and 5 visible channels 342 and 346 of the management of wastewater, the arrows shown represent the flow direction of the wastewater.

The features disclosed in the foregoing description, claims and drawings may be significant to the practice of the invention in its various forms both individually and in any combination thereof.

Claims (11)

Wastewater heat exchanger (10) for dishwashers, in particular commercial dishwashers, comprising at least two channel forming plates (102, 104, 106, 108) and at least one heat transfer plate (203, 205, 207),
wherein the at least two channel molding plates (102, 104, 106, 108) are made of a plastic material and each channel molding plate (102, 104, 106, 108) on at least one side of the channel molding plate (102, 104, 106, 108) one on one side open channel (322, 324, 326, 342, 344, 346),
wherein the channel (322, 324, 326; 342, 344, 346) has an inlet opening at one end and an outlet opening at its other end, and
wherein the at least one heat transfer plate (203, 205, 207) is made of a metallic material or of a thermally conductive plastic, and wherein the at least two channel molding plates (102, 104, 106, 108) and the at least one heat transfer plate (203, 205, 207 ) are arranged such that the open side of a channel of a first channel molding plate faces the open side of a channel of a second channel molding plate, wherein the open sides of the two channels are closed by a heat transfer plate disposed between the two channel molding plates. A wastewater heat exchanger (10) according to claim 1, characterized in that the channel from an outer region of the channel molding plate (102, 104, 106, 108) in an inner region of the channel molding plate (102, 104, 106, 108) and from there back to an outdoor area the channel molding plate (102, 104, 106, 108) extends. Wastewater heat exchanger according to claim 1 or 2, characterized in that the channel is formed spirally. A waste water heat exchanger according to any one of the preceding claims, comprising two duct plates (104, 106) forming a duct on both sides, two duct plates (102, 108) forming a duct on one side only, and three heat transfer plates (203, 205, 207) ), which are arranged so that a total of three pairs of opposing channels (322, 346, 324, 344, 326, 342) are formed, wherein the opposite channels of each pair are separated by a heat transfer plate (203, 205, 207). Wastewater heat exchanger according to one of the preceding claims, characterized in that the channel molding plates (102, 104, 106, 108) and the heat transfer plates (203, 205, 207) are glued together. Wastewater heat exchanger according to one of the preceding claims, characterized in that the channel molding plates (102, 104, 106, 108) and the heat transfer plates (203, 205, 207) are welded together. Wastewater heat exchanger according to one of the preceding claims, characterized in that the at least one heat transfer plate (203, 205, 207) consists of thermally conductive plastic, the additives are added, which increase the thermal conductivity. Wastewater heat exchanger according to one of claims 1 to 6, characterized in that the at least one heat transfer plate (203, 205, 207) consists of copper or stainless steel. Wastewater heat exchanger according to one of the preceding claims, characterized in that the channel molding plates (102, 104, 106, 108) are produced by injection molding. Wastewater heat exchanger according to one of the preceding claims, characterized in that the thickness of the at least one heat transfer plate is 0.1 mm to 1.5 mm. Dishwasher, in particular a commercial dishwasher, with a waste water heat exchanger (10) according to one of the preceding claims

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