DE202012012960U1 - Heating device in a water-conducting household appliance - Google Patents

Abstract

Heating device for heating a fluid flow, in particular a liquid flow (I) in a water-bearing household appliance, characterized in that the heating device has a heat pipe (1) with a heat-absorbing evaporator section (23) and a heat-emitting condenser section (25) which is in thermal connection with the Liquid flow (I) is.

Description

The invention relates to a heating device for heating a liquid flow in a water-conducting household appliance according to the preamble of claim 1 and such a water-conducting household appliance according to claim 14.

In general, the use of heat pipes (heatpipes) is known in many areas. Such a heat pipe contains a hermetically sealed volume which is filled with a working medium (for example water). The working fluid fills the volume to a small extent in liquid, for the most part in a vaporous state. When a heat enters the heat pipe, the working medium begins to evaporate. As a result, the pressure in the overlying vapor space is locally increased above the liquid level. The resulting vapor flows therefore in the direction of a heat transfer surface of the heat pipe, where it condenses due to low temperatures. As a result, the previously absorbed heat is released again. The liquid working medium can then be guided back to the evaporator by gravity and / or by a capillary force.

From the DE 10 2007 060 193 A1 is a generic heating device for heating a liquid flow in a water-conducting household appliance known. The heating device is arranged, for example, as a thick-film element on the outside of a cylindrical housing wall of the pump housing. The cylindrical housing radially inside a pressure chamber through which the pumped by a pump impeller liquid is guided under pressure to an outlet-side discharge nozzle. The attachment of the thick film heater on the outside of the pump housing is associated with high production costs. In addition, the thermal resistance to be overcome of the metal-made pump housing is considerable, whereby heat losses occur in heating operation.

From the DE 10 2004 055 926 A1 is the use of a heat pipe (heat pipe) in a dishwasher known. Accordingly, in a final rinse drying step, the air to be dried is brought into thermal contact with a heat-receiving evaporator section of the heat pipe, thereby condensing water from the air to be dried. Subsequently, the dried air is brought into thermal contact with the heat-emitting condenser section of the heat pipe to heat the dried air. The thus dried and heated air is returned to the washing room.

The object of the invention is to provide a heating device for heating a liquid flow in a water-conducting household appliance, which is simple in construction and works with reduced heat losses.

The object is solved by the features of claim 1 or 14. Preferred developments of the invention are disclosed in the subclaims.

The invention relates to a heating device for heating a liquid flow in a water-conducting household appliance. According to the invention, the heating device has a heat pipe which has a heat-absorbing evaporator section and a heat-emitting condenser section. For heating the liquid flow is heat-emitting condenser section in thermal communication with the liquid flow. In contrast to the generic state of the art, therefore, according to the invention, the heat pipe is integrated directly in the hydraulic circuit of the water-conducting household appliance, for example, as a water heater. In this way, the circulated in the device operation liquid is heated directly by means of the heat pipe.

In such a heat pipe (heat pipe), the energy is released almost exclusively at the condensation surface of the heat pipe. This means that by condensing the vaporous working fluid, a targeted release of energy takes place at the condensation surface. In contrast, in the uncooled heat pipe area, where no condensation of the vaporous working fluid takes place, only a significantly reduced energy transfer takes place. For the energy transfer optionally the available surfaces can be used completely for condensation. This circumstance can be used either to reduce space or to reduce the required energy density during energy transfer.

The hydraulic circuit of the household appliance has known liquid lines and / or a circulating pump, with the aid of which, for example, rinsing liquid is circulated and passed through the washing compartment of a dishwasher. The heater can be integrated directly in the liquid line in the manner of a water heater. In this case, the heat pipe may preferably have a liquid passage through which the liquid flows. The heat pipe limits a fluid-tight closed space in which a working fluid is provided, with which a heat transfer from the heat-absorbing evaporator section to the heat-emitting condenser section of the heat pipe. The heat-emitting condenser section of the heat pipe can while being directly in thermal contact with only one heat transfer surface in fluid flow through the fluid passage. To further improve the thermal conductivity between the heat pipe and the liquid flow, the inner tube through which liquid flows can additionally have on the inside a flow contour and / or flow guide elements, for example a wave profile which assists heat transfer into the liquid flow.

In addition, the heat pipe allows a free surface design on the inner tube delimiting the liquid flow. With such a free surface design, the following advantages are summarized: On the one hand, a surface enlargement of the heat exchange surface on the inner tube can be carried out in a simple manner. In addition, a fluid mechanical optimum shape can be achieved both in terms of increased heat transfer and in terms of flow efficiency. In addition, as already mentioned above, small micro-vortexes can be generated in the liquid flow, which further increase the heat transfer without appreciably increasing the flow resistance. Finally, with appropriate design, the flow contour can increase the component rigidity of the inner tube. Due to the increased component stiffness, in turn, material can be saved, for example stainless steel, whose material thickness can be reduced to a range of 0.2 or 0.3 mm.

Instead of the above-mentioned wave profile can be provided as a flow contour any other suitable surface structure. By way of example, the above-mentioned corrugated profile may be a corrugated corrugated structure or a cross-corrugated corrugated structure or a diagonally corrugated corrugated structure. In this way, micro vortexes can be generated at the liquid flow limiting inner wall, with the aid of which the heat exchange is increased. If appropriate, the flow contour may also have a diamond-shaped bump structure, for example.

The term household appliance is broad in the context of the invention, in particular, for example, permanently installed water heater should be included. Moreover, the invention can be used in any other water-conducting household appliance, for example in washing machines, dishwashers or even in coffee machines or coffee machines.

The heat pipe according to the invention as such is not fixed to a tube geometry. Rather, the heat pipe may have any shape, as long as a sufficient thermal contact with the liquid flow to be heated is ensured. With regard to a reduction in space, however, it is advantageous if the heat pipe is designed circular in profile. In a space-saving design, the heater can be designed as a double-walled heating pipe. The heating tube may have an outer tube forming the heat pipe, an inner tube forming the fluid passage and an intermediate annular gap. The annular gap, together with a collecting space described later, can form the aforementioned fluid-tight closed space of the heat pipe. In this way, the entire cylindrical outer surface of the inner tube serves as a heat transfer surface.

At the heat-emitting evaporator section of the heat pipe, the heat is introduced into the heat pipe. For the heat input, the evaporator section may have a heating element which can be actuated in particular electrically. With regard to the reduction of heat losses, the heating element, such as a tubular heater, may be disposed within the fluid-tight closed space of the heat pipe.

Depending on the design of the heat pipe, the working fluid condensed on the condensation surface (heat transfer surface) can return to the evaporator section by gravity or, for example, by capillary action. In a preferred embodiment according to the invention, the heat pipe is designed as a so-called two-phase thermosyphon or a gravitational heat pipe. In such a gravity heat pipe, the fluid-tightly closed space is divided into a, in installation position, bottom-side collecting space for the liquid working fluid and into a vapor space arranged above it. When heat is introduced into the collecting space, the liquid working fluid is evaporated and thus transferred into the vapor space. The vaporous working fluid condenses with heat release on a heat transfer surface and then returns automatically in liquid form due to gravity back into the plenum. For circulating the working fluid, therefore, the heat pipe does not require any additional auxiliary energy for activating a circulating pump with which the working fluid can be returned. This minimizes both the maintenance and the operating costs.

To form the bottom-side collecting space, the outer tube may have a radially outwardly projecting heat pipe housing, which delimits the collecting space. The inner tube and the outer tube of the double-walled heating tube may be connected to each other at their axially opposite sides in a fluid-tight manner. By way of example, the nested inner and outer tubes may be on each of the axially opposite ones End faces to be joined together to form a double-walled annular collar.

In a preferred embodiment, the heating device can be integrated as a water heater in a circulating pump, with which the fluid is forcibly circulated in a hydraulic circuit, for example.

Preferably, the heat pipe can be arranged within a pump housing in a flow chamber of the circulation pump. As a flow chamber, the circulation pump can have on the inlet side a paddle wheel chamber with a paddle wheel conveying the fluid. On the outlet side, the circulation pump may have a pressure chamber, which is arranged downstream of the Schaufelradkammer and into which the fluid conveyed by the impeller flows at high flow velocity. The pressure chamber may transition in the flow direction in a flow channel, which leads the liquid to an outlet-side discharge nozzle. Preferably, the heat pipe can be facing with its heat transfer surface of the pressure chamber. The pressure chamber preferably extends annularly around a central axis of the circulation pump. In addition, the pressure chamber may be bounded radially outward by the inner tube of the double-walled heating tube. The liquid flow moves in the pressure chamber in a rotational movement, that is tangent to the inside of the inner tube. In this way, a comparatively long residence time of the liquid flow in the pressure chamber results.

As mentioned above, the inner tube of the heat pipe can radially outwardly limit the pressure chamber of the circulation pump. The outer tube of the heat pipe, however, can be arranged spaced from a cylindrical, outer housing wall of the pump housing via an intermediate air gap. In this way it is ensured that the vaporous working fluid is largely not condensed on the outer tube, but alone on the inner tube and thus gives off heat to the liquid flowing through.

In the cylindrical housing wall of the pump housing, a recess may be provided through which the heat pipe housing defining the collecting space of the heat pipe protrudes. Optionally located on the heat pipe housing sockets of the heating element are thus accessible from the outside.

The cylindrical outer housing wall of the pump housing on the front side via a chamber wall into a radially inner cylindrical pump wall over. The inner cylindrical pump wall defines together with the inner tube of the double-walled heating tube, the pressure chamber.

Preferably, the double-walled heating tube is fixed to the axially opposite end chamber walls of the pressure chamber. For this purpose, each end-side annular collar of the double-walled heating tube is in each case inserted in an annular groove of the facing chamber wall with the interposition of a sealant. One of the two axially spaced chamber walls forms a transition between the outer and the inner pump housing wall, while the other, axially opposite chamber wall may be a removable cover through which a drive shaft of the impeller is guided to the electric drive motor of the pump.

Instead of the above-mentioned liquid flow to be heated, any kind of fluid flow can be used regardless of the phase state. The fluid flow may also be cooled in departure from the above embodiments of the heat pipe. By way of example, the cooling space of a refrigerator can be cooled by means of the heat pipe. For this purpose, instead of the liquid flow to be heated by means of a blower, a stream of air to be cooled can be passed through the heat pipe. In a cooling operation, for example, the annular gap of the heat pipe acts as a heat-absorbing evaporator section of the heat pipe, while the heat pipe housing acts as a heat-emitting condenser section. In the heat pipe housing - in contrast to the previous embodiments - no radiator, but a suitably designed cooling element is arranged.

In such a cooling operation, heat is removed from the air stream flowing along the inner tube, which heat is transferred to the working medium located in the annular gap. The working fluid is transferred by the energy input from the air flow from the liquid phase to the vapor phase. The vaporous working medium is in turn condensed on the cooling element.

The advantageous embodiments and / or further developments of the invention explained above and / or reproduced in the subclaims can be used individually or else in any combination with one another, for example in the case of clear dependencies or incompatible alternatives.

The invention and its advantageous embodiments and further developments and advantages thereof are explained in more detail below with reference to drawings.

Show it:

1 to 3 in each case different views of a heater according to the invention in isolation;

4 a side sectional view of a circulating pump used in a hydraulic circuit of a water-conducting household appliance; and

5 different variants of an inner tube of the heater.

In the 1 to 3 is a heating device for heating a liquid flow I ( 1 or 3 ) shown according to a first embodiment. By way of example, the heating device can be a water heater installed in the hydraulic circuit of a dishwashing machine, which can be installed in one in the 1 indicated liquid line 3 is integrated. The heater has according to the 1 to 3 a double-walled heating pipe 5 on, where the outer tube 1 is designed as a heat pipe or as a heat pipe. In addition, the double-walled heating pipe has 5 a liquid-flowed inner tube 7 and an intermediate annular gap 9 ( 3 ) on. The two inner and outer tubes 1 . 7 are in accordance with the 1 to 3 arranged coaxially with each other, whereby the annular gap 9 has a constant gap width along the circumference. The annular gap 9 is together with a laterally described bottom plenum 13 Part of a fluid-tight and pressure-tight closed space 8th between the inner and the outer tube 1 . 7 , For fluid-tight encapsulation, the inner and outer tubes 1 . 7 at their opposite end faces in the axial direction in each case to a double-walled annular collar 11 put together, as it is in the 1 is shown. Every ring collar 11 of the heating tube 5 is in a manner not shown on the liquid line 3 connected.

In the 3 is the double-walled heating pipe 5 shown in the installation position. Consequently, its outer tube has 1 bottom side a radially outwardly projecting housing 17 on, a heat pipe sump or the above-mentioned collection space 13 limited. In the collection room 13 is a tubular heater 15 arranged, whose electrical connections 19 through the heat pipe housing 13 are led to the outside.

Within the fluid-tight closed space 8th is a working fluid 14 provided that when the heater is deactivated for the most part in the liquid phase bottom side in the plenum 13 collects. A minor portion of the working fluid is in the vapor phase in the annulus above 9 distributed, the steam room of the heat pipe 1 forms. When activated in the collection room 13 arranged radiator 15 is the liquid working fluid under heat in the overlying annulus 9 evaporated. The vaporous working fluid condenses on the outer surface 21 of the inner tube 7 and is automatically returned to the plenum due to gravity 13 recycled. The collection room 13 thus forms a heat-absorbing evaporator section 23 while the annulus above 9 with the heat transfer surface 21 a heat-emitting condenser section 25 of the heat pipe 1 forms.

To increase the thermal conductivity of the inner tube 7 to the liquid flowing through I, the inner tube 7 inside a wave profile example 29 on. The resulting turbulences in the liquid flow I increase the thermal conductivity, especially in the edge region of the liquid flow I.

In the 4 is in a second embodiment, the double-walled heating tube 5 not in the liquid line 3 but rather within a pump housing of a recirculation pump 30 arranged. The structure and operation of the heating tube 5 is identical to that of the first embodiment. Therefore, the description of the 1 to 3 directed.

Like in the 4 indicated, is a liquid line 31 with its line end to an intake manifold 33 the circulation pump 30 pushed, which here coaxial with a central axis 35 the circulation pump 30 runs. The circulation pump 30 points around the central axis 35 rotatable paddle wheel 37 on that in a paddle wheel room 38 inside the pump housing 40 is provided. The paddle wheel 37 is via a drive shaft 40 with a not indicated electric motor in drive connection. The bucket wheel space 38 is on its radially outer side over an annular gap 42 with an annular pressure chamber 43 in fluid communication. The pressure room 43 extends rotationally symmetrical about the central axis 35 and radially outward over the intake manifold 33 , Between the paddle wheel space 38 and the pressure room 43 is in the annular gap 42 a stationary stator 44 provided, the non-rotatably on a bearing seat of the pump housing 40 sitting. The baffles of the stator 44 are made steep, so that the inflowing liquid flow I in high flow velocity and in the radial circumferential direction of the pressure chamber 33 flows through. The pressure chamber 33 is radially outward through the inner tube 7 the double-walled heating pipe 5 limited. This means that the liquid flow is almost tangential along the inner tube 7 flows. This tangential flow is also due to the wave profile 29 supported on the inner tube. The residence time of the liquid flow I within the pressure chamber is correspondingly high 43 , In addition, the liquid flow I by means of the stator 44 a low velocity component in the axial direction toward the downstream flow channel 46 impressed. Through the flow channel 46 the liquid flow I is tangential in an outlet side pressure port 47 and more in the liquid line 31 promoted.

In the, in the 4 installation position shown limits the inner tube 7 of the heat pipe 1 radially outside the pressure chamber 43 the circulation pump 30 , In addition, the outer tube 1 radially outward with the interposition of an air gap 49 from the outer cylindrical housing wall 39 of the pump housing 40 spaced. With the help of the air gap 49 is a heat transfer through the outer tube 1 reduced, in favor of a heat transfer via the inner tube 7 to the liquid flow I.

The pump housing 40 is in the 4 executed essentially in two parts, one in the 4 left housing part 51 the cylindrical outer housing wall 39 having, in one piece via a vertical chamber wall 53 in a radially inner cylindrical pump wall 54 passes. On the, the pressure chamber 43 facing side, the chamber wall 53 an annular groove 55 in, in the interposition of a sealing element a frontal collar 11 the double-walled heating pipe 5 is inserted. The axially opposite annular collar 11 is in contrast in a corresponding annular groove 56 of the second housing part 57 inserted fluid-tight, which is the pressure chamber 43 in the 4 closes fluid-tight to the right.

In the 5 are different variants of the inner tube 7 represented, after which additional flow guide elements 59 inside on the inner tube 7 are formed, with the aid of the liquid flow I can be impressed for supporting the heat transfer flow pattern.

Instead of the above-mentioned liquid flow I, any type of fluid flow independent of the phase state can be used. Although the fluid flow I is heated in the above-mentioned embodiments by application of the heat pipe. In extension of the embodiments shown, however, the heat pipe can also be used for cooling a fluid flow. By way of example, the cooling space of a refrigeration device with the aid of the heat pipe 1 be cooled. For this purpose, instead of in the 3 described liquid flow I with the help of a fan to be cooled air flow I through the heat pipe 1 be guided. In a cooling operation, the annular gap acts 9 the heat pipe as a heat absorbing evaporator section of the heat pipe, while the heat pipe housing 17 acts as a heat-emitting capacitor section. In the heat pipe housing 17 is - in contrast to the previous embodiments - no radiator 15 , But arranged a suitably designed cooling element.

In cooling mode, this is along the inner tube 7 flowing air flow I extracted heat, which is on the in the annular gap 9 working medium 14 is transmitted. The working medium 14 is converted by the energy input from the air flow I of the liquid phase in the vapor phase. The vaporous working medium 14 will turn on the cooling element 15 condensed.

LIST OF REFERENCE NUMBERS

1

heat pipe

3

liquid line

5

double-walled heating pipe

7

inner tube

8th

fluid-tight closed space

9

annular gap

11

collar

13

plenum

14

working fluid

15

heating element

17

Heat pipe housing

21

Heat transfer surface

23

heat-absorbing evaporator section

25

heat-emitting capacitor section

29

flow contour

30

circulating pump

31

liquid line

33

spigot

38

Schaufelradraum

40

pump housing

42

annular gap

43

pressure chamber

44

stator

47

pressure port

51

Pump housing part

53

chamber wall

55, 56

ring groove

57

Pump housing part

59

flow guide

I

liquid flow

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

• DE 102007060193 A1 [0003]
• DE 102004055926 A1 [0004]

Claims (14)

Heating device for heating a fluid flow, in particular a liquid flow (I) in a water-conducting household appliance, characterized in that the heating device is a heat pipe ( 1 ) with a heat-absorbing evaporator section ( 23 ) and a heat-emitting capacitor section ( 25 ) which is in thermal communication with the liquid flow (I). Heating device according to claim 1, characterized in that the heat pipe ( 1 ) a liquid passage (I) through which the fluid (I) flows 7 ), which extends through the radially outer heat pipe ( 1 ), and / or the heat pipe ( 1 ) a fluid-tight closed space ( 8th ), in which a working fluid ( 14 ) is provided, with which a heat transfer from the heat-absorbing portion ( 23 ) to the heat-emitting section ( 25 ) of the heat pipe ( 1 ) he follows. Heating device according to claim 1 or 2, characterized in that the heat-emitting portion ( 25 ) of the heat pipe ( 1 ) a heat transfer surface ( 21 ) for heat transfer from the fluid-tight closed space ( 8th ) of the heat pipe ( 1 ) to the liquid flow (I). Heating device according to one of the preceding claims, characterized in that the heating device as a double-walled tube ( 5 ), with a heat pipe ( 1 ) forming the outer tube, a the fluid passage ( 7 ) forming inner tube ( 7 ) and an intermediate annular gap ( 9 ), the component of the fluid-tight closed space ( 8th ) of the heat pipe ( 1 ). Heating device according to one of the preceding claims, characterized in that the heat-absorbing evaporator section ( 23 ) of the heat pipe ( 1 ) a particular electrically operable heating element ( 15 ), which in particular within the fluid-tight closed space ( 8th ) of the heat pipe ( 1 ) is arranged. Heating device according to claim 4 or 5, characterized in that the liquid-flow- through inner tube ( 7 ) in free surface design a flow contour ( 29 ), in particular, for example, a dent profile or wave profile, and / or flow guide elements ( 59 ) having. Heating device according to one of the preceding claims, characterized in that the heat pipe ( 1 ) is designed as a two-phase thermosiphon or a gravitational heat pipe, in which the fluid-tight closed space ( 8th ) is divided into a mounting space in the bottom-side collecting space ( 13 ) for the liquid working medium ( 14 ) and in a steam room ( 9 ) into which the liquid working medium ( 14 ) evaporated under heat input and at the in the steam room ( 9 ) arranged heat transfer surface ( 21 ) condenses under heat and automatically returns to the collecting space due to gravity ( 13 ) flows back. Heating device according to claim 7, characterized in that for the formation of the collecting space ( 13 ) the outer tube ( 1 ) a radially outwardly projecting heat pipe housing ( 17 ), which the collecting space ( 13 ) limited. Heating device according to one of claims 4 to 8, characterized in that the inner tube ( 7 ) and the outer tube ( 1 ) are fluid-tightly connected to one another on their axially opposite sides, in particular in each case on the face side to form a double-walled annular collar ( 11 ) are joined together. Heating device according to one of the preceding claims, characterized in that the heat pipe ( 1 ) in a flow chamber of a pump ( 30 ) is arranged, and that in particular the pump ( 30 ) as a flow chamber a Schaufelradkammer ( 38 ) with a paddle wheel conveying the fluid ( 37 ) and a pressure chamber arranged downstream thereof ( 43 ) having. Heating device according to claim 10, characterized in that the pressure chamber ( 43 ) of the pump ( 30 ) radially outside of the inner tube ( 7 ) of the double-walled heating tube ( 5 ) is limited, and / or that the outer tube ( 1 ) of the heating tube ( 5 ), in particular with the interposition of an air gap ( 49 ) within an outer cylindrical housing wall ( 39 ) of the pump housing ( 40 ) is arranged. Heating device according to claim 11, characterized in that the cylindrical housing wall ( 39 ) of the pump housing ( 40 ) a recess ( 55 ), through which the collecting space ( 13 ) of the heat pipe ( 1 ) limiting housing ( 17 protrudes. Heating device according to claim 11 or 12, characterized in that the cylindrical housing wall ( 39 ) of the pump housing ( 40 ) in a radially inner cylindrical pump wall ( 54 ), which together with the inner tube ( 7 ) of the double-walled heating tube ( 5 ) the pressure chamber ( 43 ) limited. Pump with a heating device according to one of the preceding claims.

Images