DE102017114404A1 - heater - Google Patents

Abstract

The invention relates to a heating device (1), in particular an electric instantaneous water heater, for heating an electrically conductive liquid heating medium for a heating circuit, comprising a housing (10), preferably of cylindrical basic shape, having an inflow opening (14) and an outflow opening (15). for an electrically conductive liquid heating medium, at least one, in particular rod-shaped, first electrode (30a, 30b, 30c), at least one second electrode (40), preferably designed as a cylindrical jacket electrode, which at least partially surrounds at least one first electrode (30a, 30b, 30c), wherein the electrodes (30a, 30b, 30c, 40) extend approximately parallel to each other, in particular parallel to the longitudinal axis (A) of the housing (10), and within the housing (10) from each other electrically are arranged isolated, wherein the housing (10) at least one passage opening (17a, 17b, 17c, 18) for ele Ctral leads (50a, 50b, 50c, 51) for connecting each of the electrodes (30a, 30b, 30c, 40) to an electrical potential, and at least one electrode support (61, 62) for receiving an electrode (30a, 30b , 30c, 40), wherein the electrode holder (61, 62) consists essentially of a dielectric, impact resistant, in particular ceramic, material. Moreover, the invention relates to a heating circuit (100) comprising such a heating device.

Description

The invention relates to a heating device according to claim 1 and a heating circuit with such a heating device according to claim 16.

Water heaters for heating electrically conductive liquids, in particular water, are known from the prior art, which heat a liquid flow by means of electric current by means of electrodes immersed therein. In this case, the liquid to be heated serves as an electrolyte, wherein its electrical conductivity, or conversely its specific resistance, influences the heat output. Moving carriers present in the electrolyte allow current to flow between the electrodes. Such water heaters can be operated in the low voltage range.

The heating with electric power, both for hot water treatment as well as for heating commercial and / or residential premises, is energetically and economically attractive by the increasing decentralized production of electricity by photovoltaics, wind power or the like.

From the US 2605381 A For example, a water boiler with electrodes is known wherein three conductive electrodes are arranged around a central neutral conductor. The electrodes are connected via electrode bolts, sleeves and screwed-out lead-out connecting pins with porcelain insulators or with a cover plate of the shell of the boiler. The lower ends of the electrodes are as in 1 of the US 2605381 A shown, free.

The DE 2426196 A1 describes electrodes for heating water, wherein each inner electrode is concentrically surrounded by an outer electrode in the form of a shell open at both ends.

From the WO 2009/013279 A2 For example, there is known a conductive liquid electric flow heater having three conductive electrodes and a neutral electrode installed in a hermetically sealed body and electrically isolated from the body.

The water heater known from the prior art have the disadvantage that the attachment of the electrodes in the housing is structurally complex and / or technically inadequate, in particular with regard to the sealing of the housing to the outside. In particular, there is the problem that rod-shaped electrodes erode strongly over time due to the large electrical currents and high temperatures at the ends, especially at the edges. As a result, leaks may occur in the housing of an electrode in the housing. In particular, in the structurally simple bonding of electrodes in the housing, an adhesive connection has proven to be insufficiently resistant to current and / or heat.

The present invention therefore has the object to provide a heating device for heating an electrically conductive liquid heating medium, which can be operated as reliable, safe and maintenance-free. In particular, the heater should be as compact as possible and have a high efficiency. In addition, the heater should be suitable both for heating residential and / or commercial premises and for hot water treatment.

The object is achieved by a heating device according to claim 1.

• - ein Gehäuse, vorzugsweise mit zylindrischer Grundform, das eine Zuströmöffnung und eine Abströmöffnung für ein elektrisch leitfähiges flüssiges Heizmedium aufweist,
• - mindestens eine, insbesondere stabförmige, erste Elektrode,
• - mindestens eine, vorzugsweise als zylindrische Mantelelektrode ausgebildete, zweite Elektrode, die sich im Abstand zumindest teilweise um mindestens eine erste Elektrode herum erstreckt, wobei die Elektroden sich etwa parallel zueinander, insbesondere parallel zur Längsachse des Gehäuses, erstrecken und innerhalb des Gehäuses voneinander elektrisch isoliert angeordnet sind, wobei das Gehäuse mindestens eine Durchgangsöffnung für elektrische Anschlussleitungen aufweist, um jede der Elektroden mit einem elektrischen Potential zu verbinden, und
• - mindestens eine Elektrodenhalterung zur Aufnahme einer Elektrode, wobei die Elektrodenhalterung im Wesentlichen aus einem dielektrischen, durchschlagfesten, insbesondere keramischen, Material besteht.

In particular, the object is achieved by a heating device, in particular an electric instantaneous water heater, for heating an electrically conductive liquid heating medium for a heating circuit, comprising:

• a housing, preferably with a cylindrical basic shape, which has an inflow opening and an outflow opening for an electrically conductive liquid heating medium,
• at least one, in particular rod-shaped, first electrode,
• - At least one, preferably designed as a cylindrical sheath electrode, the second electrode which extends at least partially around at least a first electrode at a distance, wherein the electrodes extend approximately parallel to each other, in particular parallel to the longitudinal axis of the housing, and electrically insulated from each other within the housing are arranged, wherein the housing has at least one passage opening for electrical connection lines to connect each of the electrodes with an electrical potential, and
• - At least one electrode holder for receiving an electrode, wherein the electrode holder consists essentially of a dielectric, impact-resistant, in particular ceramic, material.

According to the invention, the term electrode holder can be understood to mean a device, an assembly or an element for receiving an electrode, in particular for holding, fastening or supporting an electrode in or on the housing, in particular the housing wall. For example, an electrode holder as a connecting element or a multi-part component for mechanically connecting the electrode with the Be executed housing. In particular, a surface of the electrode holder covers the electrode surface in regions, wherein preferably a positive connection is produced. In particular, the electrode and the electrode holder are in a covering area in preferably direct contact, in particular direct surface contact. A slight clearance for easier assembly or disassembly or a narrow gap for backfilling, for example with a sealing material and / or an adhesive, but may be provided. In the context of the invention, the inclusion of an electrode by or in an electrode holder implies a partial covering of the electrode surface with a surface of the electrode holder, whereby in this area the direct contact between the electrode and the heating medium is prevented or at least limited.

According to the invention, the electrode holder consists essentially of a material which is dielectric and puncture resistant, in particular of an insulator. A dielectric material may be understood as an electrically weak or non-conductive solid, in particular in comparison to the electrical conductivity of an electrically conductive heating medium used. Preferably, the electrical conductivities of the material of the electrode holder and the heating medium differ by several orders of magnitude. For the purposes of the invention, a material which, in the case of a given design and dimensioning of the electrode holder and the heating voltages applied to an electrode, which are in particular in the low-voltage range, for example at alternating voltages up to 1000 V, prevents a voltage breakdown. Preferably, the electrode holder consists essentially of a ceramic material, wherein the ceramic material is in particular dielectric and puncture resistant. The electrode holder can be made entirely of a dielectric, impact-resistant, in particular ceramic, material, in particular be made in one piece from such a material. The electrode holder can also be constructed in several parts, wherein in particular only a part of the electrode holder, which receives an electrode according to the invention, can be made of a dielectric, dielectric, in particular ceramic, material. The electrode holder may also contain small amounts of another material, provided that they do not affect the function of the electrode holder according to the invention. Preferably, the material of the electrode holder is heat-resistant, in particular up to a range of 500 ° C to 2000 ° C.

Electrode holders according to the invention can be provided for receiving a first and / or second electrode, wherein electrode holders according to the invention are preferably provided only for the first electrodes.

An electrical connecting line is to be understood in particular as meaning a metallic line section for electrically contacting an electrode from outside the housing, for example in the form of a wire section extending through the through opening, a plug socket formed in the through opening or a plug pin extending out of the through opening.

An electrical potential is provided, in particular, by a voltage source outside the heating device, preferably by a connection usually laid in buildings to a voltage source in the low-voltage range, e.g. 1000 V AC voltage.

The electrodes preferably extend approximately parallel to the longitudinal axis of the housing. A first electrode is in particular rod-shaped with two front ends, preferably with a circular-cylindrical cross section and two circular end faces. In particular, the second electrode extends over the entire length of the first electrode, preferably at least over the entire free portion of the first electrode. The free section can be understood as the section of an electrode in which the electrode surface comes into fluid contact with the flow of the heating medium. The covered portion may be understood to be the portion of an electrode which is covered by an electrode holder or covered by it in relation to the flow of the heating medium. Alternatively, however, the second electrode can also extend only in sections, in particular not continuously, along the first electrode, and not over its entire length. In particular, the second electrode is flush on a bearing surface of the housing bottom and / or is flush with a bearing surface of the housing cover.

The inflow opening and the outflow opening are in particular arranged such that the housing can be filled substantially completely with the heating medium. During operation of the heating device, the electrode holders preferably dip at least partially into the heating medium. The heating medium is in particular an electrolyte aqueous solution, preferably a caustic soda, i. Sodium hydroxide (NaOH), or potassium hydroxide, i. Potassium hydroxide (KOH), dissolved in water, in particular distilled water, wherein the electrical conductivity is adjustable by the concentration. The use of other electrically conductive heating media, such as water with added salts, acids or other bases is possible.

The invention is based on the idea that an electrode is mechanically held in a defined position by the inclusion in an electrode holder according to the invention on the one hand and on the other hand electrical, electrochemical and thermal effects that can occur in a direct contact between the flow of the heating medium with the electrode surface , partially protectable. In particular, those effects which promote the erosion of the electrode can be prevented or at least reduced in the region of the reception in the electrode holder. Preferably, by receiving a front end of an electrode in an electrode holder, the frontal erosion, in particular due to small radii of curvature of the electrode (high electrical flux density), for example at the edges of the electrode can be prevented. In addition, the temperatures occurring at the electrode can be reduced. In particular, by such an electrode holder, the location of the bearing of the electrode with the prevailing electric field and the location of the seal of the housing in a structurally simple manner spatially decoupled from each other. By means of an electrode holder according to the invention, the housing can be reliably and permanently sealed to the outside in an area of the housing in which the operation of the heating device is governed by less extreme electrical, electrochemical and / or thermal conditions than at the electrode itself.

In an advantageous embodiment of the invention, three first electrodes are provided, wherein each of the first electrodes is connectable via a respective connecting line with an outer conductor of a three-phase AC voltage source. In particular, the number of first electrodes may be a multiple of three. The first electrodes are arranged in particular uniformly spaced from each other. In principle, it is also possible to provide at least one first electrode, which can be connected to a single-phase voltage source via a connecting line. Embodiments are possible in which the second electrode is electrically connected to a neutral conductor, as well as those in which the second electrode is not electrically connected to a neutral conductor, in particular in an electrically puncture-proof housing.

In an advantageous development of the invention, a second electrode is provided, which can be connected via a connecting line to a neutral conductor of a three-phase alternating voltage source, wherein the second electrode is designed in particular as a metallic sheath electrode, which extends in particular along the inside of the housing. Preferably, a second electrode encloses three centrally arranged first electrodes in the circumferential direction of the housing. In particular, a plurality of second electrodes, in particular designed as separate electrode sections, may be provided, for each of which separate through openings for one connection line each may be provided, or which may be connected within the housing to a common through opening for a connecting line. The second electrode is designed in particular in the form of a hollow cylinder or tubular section open on both sides and preferably rests against the inside of the housing.

In an advantageous development of the invention, each electrode, in particular the first electrode, is accommodated at both ends in an electrode holder. It may be provided for each electrode per an electrode holder, or a common electrode holder for a plurality of electrodes, wherein the electrodes are mutually isolated in the electrode holder, for example, by a plurality of retaining recesses. Both sides provided electrode holders have the advantage that the electrode mechanically stable, namely in particular radially and axially stored, for example, axially clamped is. Thereby, such a heater can be mounted arbitrarily oriented in space, without the risk that could solve an electrode due to gravity. In addition, the heating device can be made particularly compact, for example, when an electrode extends along the entire length of the interior of the housing, in particular from an electrode holder on a housing bottom to an electrode holder on a housing cover.

Alternatively, an electrode holder may be provided for receiving an electrode, in particular a first electrode, but also only at one of the two front ends, wherein the other front end in particular forms a free end of the electrode. Such a free end of an electrode can be provided with an electrode cover, wherein the electrode cover substantially consists of a dielectric, impact-resistant, in particular ceramic, material. Such an electrode cover can be embodied as already described with regard to the material and the function analogously to an electrode holder according to the invention. In particular, an electrode cover has the form of a cap, which is in particular attached to a free end of the electrode, in order to cover it. Preferably, an electrode cover is cylindrical with an adapted to the front end of the electrode inner recess, in particular pot-like executed. An electrode cover has the advantage that the erosion of the electrode in a free end can be prevented or at least mitigated.

In an advantageous development of the invention, the first electrode is designed as a carbon electrode, in particular a carbon rod electrode.

Preferably, a carbon electrode has a Kontaktierungsausnehmung, preferably in the form of a blind hole, into which an electrical connection cable is inserted. A connection line can be e.g. extend a few centimeters into a first electrode and in particular be glued within the Kontaktierungsausnehmung with conductive adhesive to the electrode. This ensures a reliable electrical contact. Carbon electrodes have the advantage that they are relatively cheap and electrochemically resistant. The first electrode may be coated, for example with a noble metal, such as platinum, or titanium.

In an advantageous development of the invention, the electrode holder has a front end of an electrode correspondingly shaped, in particular cup-cylindrical, holding recess into which the front end of the electrode can be inserted, in particular fitted, is. Preferably, a clearance fit is provided. In particular, the front end of the electrode is inserted into a suitably formed holding recess. Preferably, a holding portion of the electrode holder is sleeve-shaped or cap-shaped. The front end of an electrode is preferably formed circular-cylindrical, wherein the holding recess is designed as a corresponding counterpart, in particular with a matching inner cylinder. Other shapes of the front end or the retaining recess, for example a square, a star, a slot or another profile are conceivable, for example, to positively prevent rotation of the electrode in the retaining recess. In particular, the electrode holder has a holding portion which forms the holding recess, and a connecting portion for connection to the housing. The cross section of the electrode holder is not necessarily constant in the longitudinal direction. In particular, the cross section in a holding section is different from the cross section of the connecting section. For example, the connecting portion is tapered or springing back. In particular, an inner circumferential surface of the retaining recess overlaps with an outer peripheral surface of the front end of the electrode in a covering region. Preferably, the front end is inserted or pressed into the retaining recess such that no heating medium can penetrate between the electrode and the retaining recess. The depth of the retaining recess may be greater than the length of the covered portion of the electrode, which projects into the retaining recess. Preferably, the electrode lies with its end face but flush against a stop surface of the holding recess.

In an advantageous embodiment of the invention, the electrode is glued into the electrode holder, in particular with a dielectric, preferably ceramic, adhesive. In this way, on the one hand a firm connection between the electrode and the electrode holder is achieved and on the other hand prevents penetration of the heating medium in the covering area. By a dielectric adhesive, the front end of the electrode is electrically isolated from the heating medium. An adhesive layer may be formed thin, namely preferably as an intermediate layer of a clearance fit between the electrode and the holding recess of the electrode holder.

In an advantageous development of the invention, the electrode holder has a passage for carrying out a connecting line. The passageway preferably extends centrally, in particular along the longitudinal axis of the electrode holder. In particular, the through-channel forms a passage between the holding recess of the electrode holder and a through-opening of the housing for an electrical connection line. Preferably, the through-channel opens into a stop surface of the holding recess. The electrode may be electrically contacted on the front side within the holding recess by a connecting lead, either detachably, e.g. by a press or clamping contact, or firmly connected, in particular cohesively, e.g. through a soldering point. By means of an electrically conductive adhesive, a suitable electrical contacting of the connecting line can be ensured. Preferably, however, the electrode is electrically conductively connected, in particular adhesively bonded, to the connection line within a contacting recess. Due to the weakened electric field and the reduced temperatures which are achieved by an electrode holder according to the invention in the region of the front end of the electrode, an adhesive bond permanently withstands the conditions prevailing there.

In an embodiment with an electrode holder on both front ends of an electrode, a through-channel is preferably provided only in one of the electrode holders. An e.g. for technical reasons, provided in an electrode holder through-channel can by a channel closure, e.g. a plug of a suitable material, be closed. Alternatively, an electrode holder may also be integrally formed with a retaining recess closed to the housing, i. in particular without a through-passage for a connecting cable to be made.

In an advantageous development of the invention, the electrode holder is in a correspondingly shaped recess of the housing stored, in particular fitted in this. Such a recess of the housing may for example be cast or drilled. The electrode holder can be screwed into the recess, for example, pressed or glued. Preferably, the electrode holder is glued on the side of the through hole in the housing. Such an adhesive layer may have a sealing effect. Alternatively or additionally, in the recess between the electrode holder and the housing, a seal, in particular a sealing ring, for example made of rubber, be arranged, for example, inserted into a groove in the peripheral surface of the electrode holder or in a groove in the housing. In addition, a seal may be arranged between an outer side of the electrode holder and an inner side of the recess. Such a seal may be formed by a cured adhesive and / or by at least one additional layer of a sealing material.

In an advantageous development of the invention, the passage opening in the electrode holder correspondingly shaped recess of the housing is formed. In this way, an electrical connection line can be inserted from outside into the recess of the housing and further through the passageway in the electrode holder into the holding recess. In particular, the passage opening in the housing and the passageway in the electrode holder in the attached state of the electrode holder are coaxial with each other. An electrical contacting of the connecting line with the electrode in the interior of the electrode holder in this way easily and reliably executable, in particular spatially separated from fluid contact between the electrode surface and the heating medium. For example, the housing may be sealed against the outlet of the heating medium on the outside of the passage opening.

In an advantageous development of the invention, the electrode holder consists of a technical ceramic, for example having alumina, soapstone, magnesium silicate, magnesium-aluminum silicate, glass and / or porcelain. Technical ceramics are in particular heat-resistant, but also sufficiently resistant to electrochemical effects, in order to ensure a permanently reliable mounting and, in particular, reliable protection of the recorded front end of the electrode even at high heating powers of the heating device.

In an advantageous embodiment of the invention, the housing comprises a plastic or a synthetic resin, preferably polyamide or an epoxy resin, more preferably a glass fiber reinforced plastic, more preferably PA 6.6 with a glass fiber content of, for example, 20% to 50%. In particular, the housing is made therefrom, preferably cast. Dielectric plastics or synthetic resins ensure electrical insulation of the outside of the housing, in particular against the potential of the second electrode. Glass fiber reinforced plastics are available with sufficient dielectric strength, e.g. under the designation PA 6.6 GF 35 with a glass fiber content of 35% with a dielectric strength of approximately 28 kV / mm, in order, when the housing is designed with a corresponding wall thickness, e.g. between 3 mm and 15 mm, preferably between 5 mm and 12 mm, more preferably approximately 8 mm, to achieve the desired safety. By a suitable plastic or a synthetic resin, optionally with a coated or sealed surface, in particular the absorption of moisture into the housing can be prevented or reduced. In this way, the breakdown safety can be further increased. In addition, such a glass fiber reinforced plastic is sufficiently temperature resistant, dimensionally stable, and chemically resistant, especially in basic environment.

In an advantageous development of the invention, the housing is constructed in several parts, in particular in two parts, wherein the housing parts can be connected to one another via a flange. In particular, the housing consists of a first and a second housing part, which each form a flange, wherein the flange connection is preferably arranged centrally along the longitudinal axis of the housing. In particular, through holes distributed over the circumferential direction of the flange are provided for screw connections. A two-part housing is easy to manufacture, especially castable. In particular, the first housing part and the second housing part may be the same and preferably made with the same mold, e.g. by an injection molding process. Between the flange surfaces, at least one circumferential seal, in particular a flat sealing ring, e.g. made of rubber, preferably in a recess in the flange surfaces, be inserted.

In an advantageous development of the invention, the connection line for the second electrode is arranged in a radially extending groove of a flange surface. In one or both abutting flange surfaces, a depression can be formed towards the inside of the housing, into which, in particular, an annular connecting line for contacting the second electrode can be inserted, preferably between two circumferential seals. A connecting line can be soldered to the second electrode, preferably pointwise, in particular brazed. Such a connecting line can be led out of the housing, for example via a radially extending groove, for example via a Contacting by means of a cable lug for a connection cable.

In an advantageous development of the invention, an inflow channel or an outflow channel are formed on one end side of the housing, in particular in a housing bottom or a housing cover, preferably each tangential to the circumferential direction of the housing opening or discharging, that in the housing a helical flow a heating medium forms around the longitudinal axis. In particular, the inflow opening and the outflow opening are each formed in connecting pieces of the housing, which are preferably aligned parallel to one another. The inflow opening is preferably formed below the housing bottom and the outflow opening above the housing cover, wherein the flow direction may also be reversed. In particular, the cross section of the inflow channel in the circumferential direction of the housing continuously decreases along the flow direction away from the inflow opening, while the cross section of the outflow channel continuously increases in the circumferential direction of the housing along the flow direction to the outflow opening. In this way, a possible laminar flow of the heating medium in the housing, in particular with a speed component in the circumferential direction and in the longitudinal direction of the housing. In particular, a gentle introduction or discharge of the heating medium in or out of the housing is largely ensured without turbulence. Characterized a spatially and temporally as uniform as possible heating of the heating medium is achieved in the housing.

The above object is also achieved by a heating circuit according to claim 16.

• - eine Heizvorrichtung,
• - einen Wärmetauscher,
• - eine Umwälzpumpe und
• - Leitungen für das Heizmedium, die mit einer Zuströmöffnung und einer Abströmöffnung der Heizvorrichtung verbunden sind,

dadurch gekennzeichnet, dass die Heizvorrichtung erfindungsgemäß ausgeführt ist.In particular, the object is achieved by a heating circuit for an electrically conductive liquid heating medium, in particular as a primary circuit of a heating system for residential and / or commercial premises or for hot water treatment, comprising:

• a heating device,
• a heat exchanger,
• - a circulation pump and
• Pipes for the heating medium, which are connected to an inflow opening and an outflow opening of the heating device,

characterized in that the heating device is designed according to the invention.

A heating circuit with a heating device, a heat exchanger, a circulation pump and lines for the heating medium is known from the prior art. By a combination with a heating device according to the invention, however, the same advantages arise for a heating circuit according to the invention as have already been described in connection with the heating device according to the invention. In particular, a heating circuit can be operated as maintenance-free as possible, since the heater is reliable and permanently tight.

In particular, the heating circuit according to the invention is thermally coupled via a heat exchanger to a secondary circuit. The heat generated in the primary circuit by the heater according to the invention is transferred to the secondary circuit via the heat exchanger. In the secondary circuit, in particular another, preferably electrically non-conductive, heating medium itself is heated for consumption, for example, water used as hot water, or for heating residential and / or commercial premises, in particular via radiators. In particular, the heating circuit according to the invention can be easily retrofitted as a primary circuit in a heating system with an existing secondary circuit.

In an advantageous embodiment of the invention, the heating medium has an electrical conductivity between 100 μS and 10000 μS, preferably between 500 μS and 5000 μS, more preferably between 700 μS and 2000 μS, more preferably between 800 μS and 1200 μS, more preferably about 1000 μS (μS: microsiemens, ie 1 × 10 ^-6 Siemens). In this way, the heater or the heating circuit in the supply of voltages in the low voltage range, in particular when connected to a household single-phase AC voltage of 220 V to 230 V or when connected to a three-phase AC voltage of 380 V to 400 V, sufficient heating power for heating of residential and / or commercial premises.

• 1 eine schematische Darstellung einer Ausführungsform einer erfindungsgemäßen Heizvorrichtung in einer Seitenansicht;
• 2 eine schematische Darstellung der Ausführungsform einer erfindungsgemäßen Heizvorrichtung nach 1 in einer Schnittansicht entlang der Linie C-C;
• 3 eine schematische Darstellung der Ausführungsform einer erfindungsgemäßen Heizvorrichtung nach 1 in einer Schnittansicht entlang der Linie B-B;
• 4 eine schematische Darstellung der Ausführungsform einer erfindungsgemäßen Heizvorrichtung nach 1 in einer Draufsicht;
• 5 eine schematische Darstellung einer Ausführungsform eines erfindungsgemäßen Heizkreises mit einer an eine Dreiphasenwechselspannungsquelle angeschlossenen Heizvorrichtung.

Embodiments of the invention are explained below with reference to the drawings. Hereby show:

• 1 a schematic representation of an embodiment of a heating device according to the invention in a side view;
• 2 a schematic representation of the embodiment of a heating device according to the invention 1 in a sectional view taken along the line CC;
• 3 a schematic representation of the embodiment of a heating device according to the invention 1 in a sectional view taken along the line BB;
• 4 a schematic representation of the embodiment of a heating device according to the invention 1 in a plan view;
• 5 a schematic representation of an embodiment of a heating circuit according to the invention with a heater connected to a three-phase AC voltage source.

In the following description of the invention, the same reference numerals are used for the same and like elements. In the 1 to 4 is an embodiment of a heating device according to the invention 1 shown in different views.

1 shows a heating device according to the invention 1 in a side view. The housing 10 has a cylindrical basic shape with a longitudinal axis A and is in two parts with a first housing part 23 and a second housing part 24 running, which has a centrally located flange 19 , For example, via screw, connected to each other. The housing 10 has an inflow opening 14 and a discharge opening 15 for an electrically conductive liquid heating medium in the heating device 1 is heated by electric current. The first and second housing parts 23 respectively. 24 are the same here, especially made with the same mold. In the two adjacent flange surfaces 20 is each a groove 21 executed in the radial direction, so that a passage opening 18 for an electrical connection cable 51 in the case 10 is formed. The heater 1 is, for example for the heating of commercial and residential premises, by a liquid to be heated heating medium with adjustable electrical conductivity (eg sodium hydroxide with distilled water) flows through, wherein the medium in the housing 10 by an electric field between three, centrally located rod-shaped first electrodes 30a . 30b . 30c and a cylindrical sheath electrode arranged around it in a radial direction as a second electrode 40 is electrically heated (see 2 ). In this embodiment, the housing has 10 a capacity of about 1 l. But it can also have, for example, between 0.5 l to 10 l capacity. The electrical conductivity of the heating medium is approximately 1000 μS. The heating power of the heater may for example be 10, 15 or 30 kW.

The 2 shows a heating device according to the invention 1 in a longitudinal section. The housing 10 is on the front sides by a caseback 12 and a housing cover 13 limited, each in one piece with the first housing part 23 or second housing part 24 are executed. Inside the case 10 are three first electrodes 30a . 30b and 30c evenly spaced from each other centrally. The first electrodes 30a . 30b and 30c are designed as rod-shaped carbon electrodes, for example with a length of about 10 cm and a diameter of about 10 mm. A second electrode 40 that stretch along the inside 22 of the housing 10 extends in the circumferential direction, surrounds or surrounds the first electrode 30a . 30b . 30c , The second electrode 40 is designed as a sheath electrode in the form of a metallic hollow cylinder or pipe section and is located on both end faces of annular bearing surfaces 28 of the housing 10 at. The second electrode 40 is by a circumferential connecting cable 51 in the form of a point-by-point soldered metal ring which fits into a recess in the flange surfaces 20 is inserted in the circumferential direction and has a radial connecting line piece for connection to a cable lug, electrically contacted. The connection cable 51 is between two circumferential seals 29 arranged in the form of flat sealing rings. The first electrodes 30a . 30b and 30c (in 2 not shown) are each associated with connecting lines 50a . 50b and 50c (in 2 not shown), in Kontaktierungsausnehmungen 33 protrude into the electrodes (shown in phantom), electrically contacted, here glued with electrically conductive adhesive. The connecting cables 50a . 50b . 50c are designed for example as copper wire sections.

The first electrodes 30a . 30b . 30c are on both sides of an electrode holder 61 respectively. 62 taken in relation to 2 as upper or lower electrode holders 61 respectively. 62 be designated. The upper electrode holders 61 have passageways 63 on, through which a connecting cable 50a . 50b . 50c from the outside through a passage opening 17a . 17b . 17c in the case 10 and continue through the passageway 63 into a holding recess 64 the electrode holder 61 is guided. The retaining recess 64 is in particular designed as a pot-cylindrical recess into which a front end 31 . 32 the first electrode 30a . 30b . 30c insertable, in particular, is customizable. The upper electrode holder 61 has a continuous passageway 63 for carrying out a connecting cable 50a . 50b . 50c on while the lower electrode holder 62 preferably closed, that is at least not provided with a continuous channel or an opening. It would also be conceivable to use the same electrode holders on both sides, wherein an existing through-channel 63 at a lower electrode holder 62 simply remain unused. Here is the passageway of the electrode holder 62 through a channel closure 66 closed in the form of a plug. The first electrode 30a . 30b . 30c can in the holding recess 64 plugged and optionally additionally glued, preferably with a dielectric, in particular ceramic, adhesive.

The electrode holders 61 . 62 are made of a ceramic material that is dielectric, impact-resistant and heat-resistant. The electrode holder 61 . 62 is integrally formed from two circular cylindrical part bodies of different diameters, namely a thicker holding portion and a narrower connecting portion, wherein the retaining recess 64 is designed as an inner cylinder, for example with a depth between 3 mm and 5 mm, preferably about 4 mm, in which a front end 31 . 32 fits accurately inserted. As a result, a region of the electrode surface at a front end 31 . 32 from an inner surface of the retaining recess 64 covered so that no heating medium in fluid contact with the front end 31 . 32 can come. In this way, the first electrode 30a . 30b . 30c in the covered section at the front ends 31 . 32 protected against erosion, in particular by reducing the temperatures occurring.

The electrode holders 61 . 62 each electrode 30a . 30b . 30c are in correspondingly shaped recesses 16a . 16b respectively. 16c in the housing cover 13 or caseback 12 stored. A seal against the escape of the heating medium may be between the outer surface of the electrode holder 61 and the inner surface of the recess 16a be provided here in the form of an adhesive layer frontally outside and an additional sealing ring 65 placed in a circumferential groove of the electrode holder 61 is inserted. The sealing ring 65 could also be in a groove in the case 10 be provided. Alternatively or additionally, the housing 10 also on the outside at the passage opening 17a . 17b . 17c be sealed. Because of that, the first electrodes 30a . 30b . 30c not directly in the housing 10 received, in particular glued therein, but an electrode holder 61 . 62 is interposed between a suitable material, the location of the mechanical support from the point of the seal can be decoupled, so that prevail at the sealing point less extreme electrical, electrochemical and / or thermal conditions. The seal is thus more reliable and stable.

At the front sides of the housing 10 is in the housing cover 13 or the housing bottom 12 a discharge channel 26 or inflow channel 25 formed for the heating medium. The inflow and outflow channels 25 . 26 are, as in 3 represented as groove or trough-like depressions with in the circumferential direction of the housing 10 decreasing or increasing cross-section executed. As a result, the flow of the heating medium on the one hand as possible laminar in the interior of the housing 10 On the other hand, a helical flow along the circumferential direction of the housing results, so that an efficient and uniform heating of the heating medium is made possible. The inflow channel 25 opens into the inflow opening 14 in a connecting piece 27 while the outflow channel 26 in the discharge opening 15 another connection support 27 empties. It could also reverse the inflow on the side of the housing cover 13 and the outflow on the side of the housing bottom 12 be provided.

3 shows a sectional view of the heating device according to the invention 1 in which all three first electrodes 30a . 30b and 30c with electrode holders 62 are shown.

In 4 is a plan view of the heater according to the invention 1 shown the three through holes 17a . 17b , 17c with connecting cables 50a . 50b respectively. 50c in the form of copper wire sections. The two connecting pieces 27 are aligned the same to facilitate connection to a piping system of a heating circuit.

5 shows a schematic representation of a heating circuit according to the invention 100 with a heat exchanger 110 , a circulation pump 102 , Cables 103 for a heating medium and a heating device according to the invention 1 , The heater 1 is to a three-phase AC source 2 connected, wherein the outer conductor L1 . L2 . L3 each with a connecting cable 50a . 50b . 50c and the neutral conductor N with a connection cable 51 for a second electrode 40 electrically connected. The heating circuit 100 is provided here as a primary circuit of a heating system, via the heat exchanger 101 that of the heater 1 generated and stored in the electrically conductive liquid heating medium heat to a secondary circuit 200 is transferred, for example, for hot water treatment or for heating residential and / or commercial premises.

It should be noted at this point that all aspects of the invention described above taken alone and in any combination, in particular the details shown in the drawings, as essential for the invention claimed. The same applies to the described method steps. Variations thereof are familiar to the person skilled in the art.

LIST OF REFERENCE NUMBERS

1

heater

2

Three-phase AC power source

10

casing

12

caseback

13

housing cover

14

inflow

15

outflow

16a, 16b, 16c

recess

17a, 17b, 17c

Through opening

18

Through opening

19

flange

20

flange

21

groove

22

inside

23

first housing part

24

second housing part

25

inflow

26

outflow channel

27

spigot

28

bearing surface

29

poetry

30a, 30b, 30c

first electrode

31

first front end

32

second front end

33

Kontaktierungsausnehmung

40

second electrode

50a, 50b, 50c

connecting cable

51

connecting cable

61

electrode holder

62

electrode holder

63

Through channel

64

holding recess

65

sealing ring

66

channel closure

100

heating circuit

101

heat exchangers

102

circulating pump

103

cables

200

Secondary circuit

A

longitudinal axis

L1, L2, L2

outer conductor

N

neutral

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2605381 A [0004]
• DE 2426196 A1 [0005]
• WO 2009/013279 A2 [0006]

Claims (17)

Heating device (1), in particular electric instantaneous water heater, for heating an electrically conductive liquid heating medium for a heating circuit, comprising: a housing (10), preferably of cylindrical basic shape, which has an inflow opening (14) and an outflow opening (15) for an electrically conductive liquid heating medium, at least one, in particular rod-shaped, first electrode (30a, 30b, 30c), at least one second electrode (40), preferably designed as a cylindrical jacket electrode, which extends at least partially around at least one first electrode (30a, 30b, 30c) at a distance, wherein the electrodes (30a, 30b, 30c, 40) extend approximately parallel to one another, in particular parallel to the longitudinal axis (A) of the housing (10), and are disposed inside the housing (10) in an electrically insulated manner, wherein the housing (10) has at least one through-hole (17a, 17b, 17c, 18) for electrical leads (50a, 50b, 50c, 51) for supplying each of the electrodes (30a, 30b, 30c, 40) with an electric potential connect, and at least one electrode holder (61, 62) for receiving an electrode (30a, 30b, 30c, 40), wherein the electrode holder (61, 62) substantially consists of a dielectric, impact-resistant, in particular ceramic, material. Heating device (1) according to Claim 1 , characterized in that three first electrodes (30a, 30b, 30c) are provided, wherein each of the first electrodes (30a, 30b, 30c) via a respective connecting line (50a, 50b, 50c) with an outer conductor (L1, L2, L3 ) is connectable to a three-phase AC power source. Heating device (1) according to Claim 1 or 2 , characterized in that a second electrode (40) is provided, which is connectable via a connecting line (51) with a neutral conductor (N) of a three-phase AC voltage source, wherein the second electrode (40) is in particular formed as a metallic sheath electrode, in particular along the inside (22) of the housing (10). Heating device (1) according to one of the preceding claims, characterized in that each electrode (30a, 30b, 30c, 40), in particular first electrode (30a, 30b, 30c), is secured at both front ends (31, 32) in an electrode holder (61, 62) is recorded. Heating device (1) according to one of the preceding claims, characterized in that the first electrode (30a, 30b, 30c) is designed as a carbon electrode, in particular carbon rod electrode. Heating device (1) according to one of the preceding claims, characterized in that the electrode holder (61, 62) has a holding recess (64) corresponding to the front end (31, 32) of an electrode (30a, 30b, 30c), in particular pot-cylindrical, in which the front end (31, 32) of the electrode (30a, 30b, 30c) insertable, in particular einpassbar, is. Heating device (1) according to one of the preceding claims, characterized in that the electrode (30a, 30b, 30c) is glued into the electrode holder (61, 62), in particular with a dielectric, preferably ceramic, adhesive. Heating device (1) according to one of the preceding claims, characterized in that the electrode holder (61) has a through-channel (63) for passing through a connecting line (50a, 50b, 50c). Heating device (1) according to one of the preceding claims, characterized in that the electrode holder (61, 62) in a correspondingly shaped recess (16a, 16b, 16c) of the housing (10) mounted, in particular in this fit. Heating device (1) according to one of the preceding claims, characterized in that the passage opening (17a, 17b, 17c) in the electrode holder (61, 62) correspondingly shaped recess (16a, 16b, 16c) of the housing (10) is formed. Heating device (1) according to one of the preceding claims, characterized in that the electrode holder (61, 62) consists of a technical ceramic, for example comprising alumina, soapstone, magnesium silicate, magnesium-aluminum silicate, glass and / or porcelain. Heating device (1) according to one of the preceding claims, characterized in that the housing (10) is a plastic or a synthetic resin, preferably polyamide or an epoxy resin, more preferably a glass fiber reinforced plastic, more preferably PA 6.6 with a glass fiber content of, for example 20% to 50 %, in particular produced therefrom, preferably cast, is. Heating device (1) according to one of the preceding claims, characterized in that the housing (10) in several parts, in particular two-part, is constructed, wherein the housing parts (23, 24) via a flange (19) are connected to one another. Heating device (1) according to one of the preceding claims, characterized in that the connecting line (51) for the second electrode (40) in a radially extending groove (21) of a flange (20) is arranged. Heating device (1) according to one of the preceding claims, characterized in that on one end side of the housing (10) an inflow channel (25) or a discharge channel (26) are formed in such a manner, in particular in a housing bottom (12) or a housing cover ( 13), preferably each tangential to the circumferential direction of the housing (10) opening or discharging, that in the housing (10) a helical flow of a heating medium about the longitudinal axis (A) is formed. Heating circuit (100) for an electrically conductive liquid heating medium, in particular as a primary circuit of a heating system for residential and / or commercial premises or for hot water treatment, comprising: - a heating device, - a heat exchanger (101), - a circulation pump (102) and - lines ( 103) for the heating medium, which are connected to an inflow opening (14) and an outflow opening (15) of the heating device, characterized in that the heating device (100) according to one of Claims 1 to 15 is executed. Heating circuit (100) according to Claim 16 , characterized in that the heating medium has an electrical conductivity between 100 μS and 10000 μS, preferably between 500 μS and 5000 μS, more preferably between 700 μS and 2000 μS, more preferably between 800 μS and 1200 μS, particularly preferably about 1000 μS ,

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