DE102004035732A1 - Refrigeration device and Peltier cooling device for it - Google Patents

Abstract

A Peltier cooling device comprises at least one support part (1), a Peltier element (17) and two heat exchangers (9, 14) which are fastened on opposite sides of the support part (1), clamping the Peltier element (17).

Description

The The present invention relates to a Peltier cooling device and a refrigerator in which a such cooler is used.

One Contains Peltier element two different electrical conductors, mostly semiconductors, in one circuit are connected in series, wherein each first ends of the two conductors with each other and with a first heat bath and second ends with a second heat bath stay in contact. Depending on the direction of a through the Peltier element flowing direct current will heat from the first to the second heat bath or vice versa. A problem with refrigeration by means of Peltier effect is that cooled and warmed side of a Peltier element close to each other, and that a natural heat flow by the Peltier element of a cooling by Peltier effect counteracts. To this heat flow Keeping small, the temperature difference between the two must be If possible, sides of the Peltier element be kept low, and this is a very close thermal connection the sides of the Peltier element to the two heat baths by means of heat exchangers required. Such heat exchangers are therefore common in a Peltier cooler contain.

Around the heat transfer between the heat exchangers and the Peltier element as efficiently as possible It is intrinsically interesting to manufacture these components cooling device vorzumontieren and install as a unit in the housing of a refrigerator. It is included however difficult to clear the connection between the Peltier cooler and the housing from thermal bridges too shape. By contrast, if one builds the components of the Peltier cooling device successively in and on a breakthrough in the housing wall, so the heat transfer can easily between Peltier element and heat exchangers impaired be, and the efficiency of the finished device is bad.

task The invention is a structure for a Peltier cooling device or specify a refrigeration device, the simple installation of the cooling device in a housing wall allows the refrigerator and at the same time an efficient heat transfer ensures.

The Task is solved through a Peltier cooler according to claim 1 or a refrigeration device according to claim 19th

Around To further simplify the structure while maintaining a uniform clamping It is preferable to ensure the Peltier element on its entire surface only a single carrier part provided that one opening in which the Peltier element is arranged.

Around a direct contact between the Peltier element and the Insulation material of a refrigeration device housing too Avoid getting into the Peltier cooler is installed, the Peltier element receiving opening is preferably of a sleeve the carrier part surround. To the thermal contact between Peltier element and heat exchangers to ensure, should then expediently at least one of the heat exchangers one in the sleeve have engaging and the Peltier element contacting projection.

The Sleeve exists preferably made of a poorly heat-conductive material to a the efficiency impairing heat flow through the environment of the Peltier element from its warm to hinder its cold side.

Preferably a shoulder is formed in the sleeve receiving the Peltier element; and the Peltier element is held at that height in the shoulder, wherein the Peltier element or the projection engaging in the sleeve to the shoulder can strike to the location of the Peltier element inside the sleeve define.

Preferably this shoulder is formed approximately centrally in the sleeve, and both heat exchangers have one in the sleeve engaging projection in contact with the Peltier element.

Around to allow a simple assembly of the cooling device according to the invention, has the carrier part preferably one between the heat exchangers substantially extending parallel to the sides of the Peltier element flange on, on which the heat exchanger are anchored. Here are the locations of the flange, where the heat exchangers are anchored, preferably. in the plane of the flange from each other away. Because it is hardly possible is, completely to prevent heat from over Flange from the warm to the cold heat exchanger flows, is intended by this arrangement of anchoring points at least the zurückzulegende Made long way and thereby the heat flow is limited.

The Anchoring the heat exchanger can be achieved in particular by means of anchoring pins, such as screws or bayonet coupling pins, which are in the Flange molded mounting sleeves intervention.

To install the Peltier cooler to simplify a refrigerator, the mounting sleeves for both heat exchangers are preferably arranged projecting from a same side of the flange, so that the flange can be practically directly in contact with one of the heat exchanger, while it is spaced from the other by a space receiving the mounting sleeves which can accommodate an insulation layer of its housing wall in a mounted in a refrigerator Peltier cooling device.

A further simplification of the assembly results when the anchoring pins in all sleeves are introduced from a same side of the flange, then the anchoring pins, the one on the introduction side arranged heat exchanger anchor, first without anchoring by drilling this heat exchanger guided are and with the fixing sleeves in Anchoring engagement while standing the one on the opposite Side arranged heat exchanger anchoring anchoring pins initially without anchoring through the fastening sleeves guided are and at the second heat exchanger to be in anchorage.

Is appropriate in this case, too, that the heat exchanger disposed on the inlet side Flange only partly covered, and that the fastening sleeves, which the the other heat exchanger take anchoring anchoring pins, in a not of the introduction side Heat exchangers covered Part of the flange are arranged. Thus, these anchoring pins remain freely accessible, even if the introduction side heat exchangers is mounted and it is possible for maintenance or repair purposes only one of the two heat exchangers to solve.

A considerable Intensification of heat exchange with the Peltier element is achievable that at least one of the heat exchangers is designed as a thermosyphon, as known from WO99 / 58906, i.e. that the heat exchanger having a cavity, the heat transfer fluid simultaneously in liquid and in gaseous phase contains. By the heat transfer fluid on the warm side of the heat exchanger evaporated and the steam flows to the cold side and condenses there, can even at low temperature gradients in the heat exchanger a high thermal Transmit power become. Since the boiling temperature of the heat transfer fluid of the dense in the Cavity ruling pressure depends and this varies with the ambient temperature, is the transport effect usable by evaporation over a wide temperature range.

Around an efficient heat transfer to ensure, should the heat transfer fluid a high heat of evaporation and at the occurring during normal operation of the cooling device Temperatures as possible high saturation vapor pressure exhibit. On the other hand, too high a saturation vapor pressure requires a high Compressive strength of the heat exchanger, which can only be realized with high costs, and strong pressure fluctuations in the heat exchanger while the operation, which can lead to deformation of the heat exchanger housing, the thermally conductive Contact between heat exchanger and Peltier element. Preferably, therefore, a heat transfer fluid chosen that Under normal operating conditions, saturation vapor pressure in the environment the atmospheric pressure, in particular between 0.8 and 1.5 bar, or its saturation vapor pressure when not in use, when the device is at an ambient temperature of a maximum of 50 ° C is stored, does not exceed 5 to 6 bar. A well suited Heat transfer fluid is butane.

Around the evaporation of the heat transfer fluid to is effective, is preferably an inner wall of the cavity with a porous one Layer provided, in which the heat transfer fluid rises by capillary effect, so a big one surface to disposal stands on which it can evaporate.

A such porous Layer is particularly beneficial to one on the cold side of the Peltier element arranged heat exchanger. Here is the porous one Layer expediently on an inner wall of the cavity facing away from the Peltier element attached, by which heat in the heat exchanger accrues and heat transfer fluid in the porous Layer brings to evaporation, which then on the Peltier element facing, cooler Inner wall of the cavity precipitates.

Around an intense vapor flow from one side of the cavity to the other by forming convection cells in the vaporous heat transfer fluid to enable should be the distance between opposite walls of the Interior at least 9 mm, preferably between 9 and 15 mm.

The support part can be realized simply and inexpensively as an injection molded plastic part be.

The Peltier cooler described above is preferably in a refrigerator Mounted so that its sleeve extends through an insulating layer of the housing of the refrigerator, so that a the heat exchanger on one inside and the other on an outside of the housing too lie comes.

Of the at least one heat exchanger having a cavity is then preferred arranged in the interior of the refrigerator.

Further Features and advantages of the invention will become apparent from the following Description of exemplary embodiments with reference to the attached Characters. Show it:

1 an exploded perspective view of a first embodiment of a Peltier cooling device according to the invention;

2 an exploded perspective view of a second embodiment of a Peltier cooling device according to the invention;

3 an outside view of the support part of the cooling device 2 ;

4 a section through the cooling device 2 and a wall of a refrigerator in which the cooling device is installed;

5 an external view of a refrigerator with a cooling device according to the invention; and

6 and 7 in each case a section through an outer heat exchanger of the Peltier cooling device according to the invention

1 shows a first embodiment of the cooling device according to the invention in an exploded view. Two sprayed from a poorly heat-conductive plastic carrier part 1a . 1b are essentially each constructed of a flat flange, of which on one side four lying on a line mounting sleeves 6 . 7 stand out, of which the longer ones 7 each with triangular wings 8th are stabilized. The two support parts 1a . 1b are provided to be mounted spaced apart from one another on a wall of a refrigerator housing as shown in the figure.

According to a modification, the two support parts 1a . 1b by in the figure as dashed outline drawn bridge sections 1c one-piece and a central opening 4 be connected.

A first heat exchanger 9 includes a rectangular base plate 10 with four holes at the corners 11 , a massive metallic projection projecting from the front of the base plate 12 and from the back of the base plate outgoing, not shown in the figure, known per se heat dissipation elements. The cuboid projection 12 is sized to fit in the opening 4 engages when the holes 11 the base plate 10 with narrower holes 13 the sleeves 6 aligned. To attach the first heat exchanger 9 on the support part 1 serve in the figure, not shown, the screws; from the back of the base plate 10 introduced, the holes 11 traverse freely and into a preformed or self-tapped thread of the holes 13 intervention.

A second heat exchanger 14 has the shape of a cuboid aluminum with protruding at the front heat exchange ribs 15 and one protruding at the back, not in 1 but only in the sectional view of the 4 visible advantage 16 , The depth of the projection 16 is sufficient to a disc-shaped Peltier element 17 between the two protrusions 12 . 16 to keep the heat exchanger trapped when both heat exchangers 9 . 14 firmly on the support parts 1a . 1b are mounted.

From the back of the second heat exchanger 14 stand in alignment with the sleeves 7 the carrier part 1 four feet 18 each with a central hole 19 (please refer 4 ), whose diameter is smaller than that of an aligned bore 20 the sleeves 7 , The second heat exchanger 14 is on the carrier part 1 fixed with the help of screws 21 , which thread themselves through the holes 20 extend and with a preformed or through the screws 21 self-cut thread of the holes 19 engage.

2 shows a second cooling device according to the invention in an exploded view. A sprayed from a poorly thermally conductive plastic carrier part 1 is essentially composed of a flat flange 2 with a central, from a sleeve 3 surrounding opening 4 , The sleeve 3 is made up of two sections 3a . 3b , where the section 3a that is between the flange 2 and the section 3b lies, has a larger free cross-section than the latter. The two sections 3a . 3b are by a shoulder 5 connected.

To the corners of the section 3a are four stubby mounting sleeves 6 formed. Four more mounting sleeves 7 , each with triangular wings 8th stabilized, are at the flange 2 arranged near its outer corners. All pods 3 . 6 . 7 extend to the same, in 2 the viewer facing side of the flange 2 ; the opposite side of the flange 2 is just.

A first heat exchanger 9 is essentially identical to the heat exchanger 9 out 1 ; only his in 1 elongated base plate 10 is in 2 shown in square. The cuboid projection 12 of the heat exchanger 9 here is sized to fit in the sleeve 3 is insertable and its section 3a on essentially the entire free cross section and in depth to school ter 5 or just before filling. The holes 11 the base plate 10 aligned with the holes 13 the sleeves 6 when the lead 12 in the sleeve 3 is introduced.

A second heat exchanger 14 is completely identical to the heat exchanger 14 of the 1 , The cross section of his projection 16 (please refer 4 ) fills the section 3b the sleeve essentially free of play; its depth is sufficient to form a disk-shaped Peltier element 17 between the two protrusions 12 . 16 to keep the heat exchanger clamped. Also the Peltier element 17 is from the sleeve 3 Surrounded essentially without play, so that an undesirable heat flow from the warm to the cold side of the Peltier element 17 only through the Peltier element 17 itself or by the poor heat-conducting material of the sleeve 3 can take place.

3 shows a view of in 2 hidden rear side of the carrier part, wherein the protruding from the front sleeves 3 . 6 . 7 and wings 8th drawn with dashed outlines. It can be seen on the lower inner wall of the section 3a two of the flange 2 up to the shoulder 5 extending grooves 22 , which are intended to provide electrical supply lines at the level of the shoulder 5 between the projections 12 . 16 the heat exchanger clamped Peltier element 17 take.

4 shows the Peltier cooling device of 2 in the assembled and in a wall 23 a refrigeration device housing inserted state. The wall 23 each has a solid outer and inner skin 24 respectively. 25 made of metal or plastic and an intervening, filled with not shown in the figure thermally insulating foam gap 26 on. Outer and inner skin 24 respectively. 25 are each with openings for passing the projections 3 . 6 . 7 . 8th of the flange 2 or section 3b the sleeve 3 Mistake. On the outer skin 24 a contiguous opening can be provided for all said protrusions; the inner skin 25 has an opening 27 whose edges are outside on the shoulder 5 and four holes 28 that with the holes 19 and 20 aligned. By the sleeves 7 are made slightly shorter than the section 3a , When tightening the screws, the inner skin 25 put something under tension, so she - possibly supported by a not shown in the figure, between her and the shoulder 5 clamped sealing ring - foam-tight at the shoulder 5 is applied.

For mounting the refrigerator is initially the carrier part 1 with in the opening of the wall 23 engaging sleeve 3 on the outer skin 24 the Wall 23 and matching the second heat exchanger 14 placed in the interior of the refrigerator. By screwing carrier part 1 and heat exchangers 14 with the help of screws 21 Both parts are attached to each other as well as to the wall 23 fixed. Subsequently, the Peltier element 17 from the outside into the opening 4 the sleeve 3 inserted, and then the lead 12 of the heat exchanger 9 in the opening 4 inserted. The base plate 10 of the heat exchanger 9 is bolted to the heat exchanger 9 and the carrier part 1 to connect with each other and at the same time the Peltier element 17 between the polished surfaces of the projections 12 . 16 clamp and thus an unimpeded heat flow between the Peltier element 17 and the heat exchangers 9 . 14 sure.

If that is in 4 only fragmentarily shown heat dissipation element 29 the holes 11 the base plate 10 not covered, it may be pre-assembled on this or preformed in one piece with her, if the base plate 10 on the support part 1 is attached; otherwise it will only be after mounting the base plate 10 attached to this.

Once the carrier part 1 and the heat exchanger 9 connected together and thereby the inner skin 25 against the shoulder 5 is pressed, the gap can 26 be filled with insulating foam. Since the foam at no point with the heat exchangers 9 . 14 does not interfere with their subsequent disassembly for the purpose of repair or maintenance. Unless the heat dissipation element 29 the heads of those in the pods 6 . 7 hidden covered screws, if necessary, a single of these heat exchangers can be removed.

The structure of the mounted inside the refrigerator heat exchanger 14 is determined by 4 explained in more detail. The made of solid metal, preferably aluminum, existing projection 15 hangs in one piece with a cuboid housing 30 together, that on one of the tab 16 facing away from the ribs 15 wearing. A tightly closed cavity 31 In the interior of the housing contains a heat transfer fluid, such as butane, partly in the liquid, partly in the gaseous state. At the ribs 15 adjacent inside of the cavity 31 is a porous layer 32 attached, which dips in its lower portion in the liquid heat transfer fluid, so that the latter in the pores of the layer 32 rise and spread over the entire height of the inner wall.

The porous layer may be formed of various materials. A first possibility is a ceramic material which, for example, in the form of an emulsion of fine particles, for example of aluminum oxide or silica gel, is sprayed or painted onto the inner wall and becomes permanent with the aid of a binder contained in the emulsion stick layer solidified. Alternatively, the layer may also consist of fiber material, for example glass or carbon fiber, natural textile fiber or synthetic fluid resistant to the heat transfer fluid, which is glued to the inner wall or between a grid (not shown) and the inner wall is clamped.

From the ribs 15 Heat absorbed from the interior of the refrigerator causes the evaporation of heat transfer fluid from the porous layer 32 which subsequently adjoins the opposite inner side of the cavity 31 at the level of the Peltier element 17 cooled projection 16 condenses and heats it. Thus, the heat flow, on a large surface in the heat exchanger 14 occurs, effective on the comparatively small cross-sectional area of the projection 16 bundled and in the lead 16 achieves a high power flux density, which allows the temperature jump in the Peltier element 17 small and to keep its efficiency high.

In order to favor the formation of convection cells in the vapor phase, the heat transfer through the cavity 31 significantly promote the width of the cavity 31 set between the porous layer and the opposite inner side to about 10 mm. The other dimensions of the cavity 31 have little effect on its heat transfer capability and can be determined in terms of convenience, typically between 10 and 20 cm.

To ensure sufficient pressure capacity of the heat exchanger 9 When not cooled, its walls are made of aluminum with a thickness of at least 5 mm.

Since at the in 4 shown embodiment, the back of the housing 30 the inner skin 25 Not touched, too, much of this back can heat from the interior to the case 30 penetration. In order to use this heat effectively for the evaporation of heat transfer fluid, can also on this side of the cavity 31 a porous layer not shown in the figure may be provided, however, the height of the projection 16 lying wall area spared, so as not to interfere with the condensation of the heat transfer fluid.

The heat dissipation element 29 on the outside of the refrigeration device housing can be realized in different ways. 5 shows a perspective view of a refrigerator according to the invention from behind an embodiment in which this heat dissipation element 29 one attached to the here hidden base plate tank 33 for a heat transfer fluid and a pump, the heat transfer fluid through a mounted on the rear panel of the cooling coil assembly 34 circulates.

Alternatively, as in 6 shown, the external heat exchanger 9 as the inner 14 as a hollow, partially filled with gaseous and partly with liquid heat transfer fluid housing 35 with cooling fins 36 be realized, for its dimensions and wall thicknesses the same applies, as above to the heat exchanger 9 executed. The lead 12 is at the bottom of this case 35 arranged so that over the projection 12 Incoming heat first, the supply of liquid heat transfer fluid in the lower region of the inner cavity 37 of the housing 35 reached. This heat reaches the arranged on the opposite side of the housing cooling fins 36 via convection of the liquid heat transfer fluid or by its evaporation and subsequent condensation at the cooling fins 36 adjacent wall of the housing 35 , The heat transfer fluid used in this heat exchanger can, as in the case of the heat exchanger 9 Be butane; both heat exchangers are designed to tolerate an internal pressure of 5 bar, which may occur when the Peltier cooler is stored at an ambient temperature of 50 ° C, without plastic deformation or leakage.

At the in 7 shown in section embodiment of the outer heat exchanger 9 is the lead 12 at mid-height on the wall of the housing 35 arranged above the mirror 38 the heat transfer fluid in the cavity 37 , A porous layer 32 extends from the bottom of the cavity 37 up to the level of the projection 12 so that over the lead 12 incoming heat is essentially the porous layer 32 and heats the heat transfer fluid therein. It therefore satisfies a comparatively low on the projection 12 incoming thermal power to the heat transfer fluid in the porous layer 32 Efficiently evaporate and so the heat from the projection 12 Dissipate touched Peltier element.

Claims (21)

Peltier cooling device with at least one support part ( 1 ; 1a . 1b ), a Peltier element ( 17 ) and two heat exchangers ( 9 . 14 ) located on opposite sides of each support member ( 1 ; 1a . 1b ) the Peltier element ( 17 ) are clamped attached. Peltier cooling device according to claim 1, characterized in that the Peltier element in an opening ( 4 ) of the single carrier part ( 1 ) is arranged. Peltier cooling device according to claim 2, characterized in that the opening ( 4 ) of a sleeve ( 3 ) of the carrier part ( 1 ) is surrounded, and that at least one of the heat exchangers ( 9 . 14 ) a protruding into the sleeve projection ( 12 . 16 ) in contact with the Peltier element ( 17 ) having. Peltier cooling device according to claim 3, characterized in that the sleeve ( 3 ; 3a . 3b ) is formed of poor thermal conductivity material. Peltier cooling device according to claim 3 or 4, characterized in that in the sleeve ( 3 ) one shoulder ( 5 ) and that the Peltier element ( 17 ) in the sleeve ( 3 ) at the level of the shoulder ( 5 ) is held. Peltier cooling device according to claim 5, characterized in that the shoulder ( 5 ) approximately in the middle of the sleeve ( 3 ) is formed, and that also the second heat exchanger ( 14 ) one in the sleeve ( 3 ) engaging projection ( 16 ) in contact with the Peltier element ( 17 ) having. Peltier cooling device according to one of the preceding claims, characterized in that the carrier part ( 1 ) between the heat exchangers ( 9 . 14 ) extending flange ( 2 ), to which the heat exchangers ( 9 . 14 ) are anchored to each other in the plane of the flange spaced apart locations. Peltier cooling device according to claim 7, characterized in that on the flange ( 2 ) Fixing sleeves ( 6 . 7 ), in which the two heat exchangers ( 9 . 14 ) anchoring anchoring pins. Peltier cooling device according to claim 8, characterized in that the fastening sleeves ( 6 . 7 ) for both heat exchangers ( 9 . 14 ) from a same side of the flange ( 2 ) stand out. Peltier cooling device according to claim 8 or 9, characterized in that the anchoring pins in all mounting sleeves ( 6 . 7 ) from a same side of the flange ( 2 ) and that the first ( 9 ) the heat exchanger ( 9 ; 14 ) anchoring anchoring pins initially without anchoring by drilling ( 11 ) of the first heat exchanger ( 9 ) are guided and with the respective associated mounting sleeve ( 6 ) in anchoring engagement, while the second heat exchanger ( 14 ) anchoring anchoring pins ( 21 ) first without anchoring engagement by the respectively associated fastening sleeve ( 7 ) and at the second heat exchanger ( 14 ) are in anchorage engagement. Peltier cooling device according to claim 10, characterized in that the first heat exchanger ( 9 ) the flange ( 2 ) only partially covered, and that the fastening sleeves ( 7 ) connecting the second heat exchanger ( 14 ) anchoring anchoring pins ( 21 ), in one not from the first heat exchanger ( 9 ) covered part of the flange ( 2 ) are arranged. Peltier cooling device according to one of claims 8 to 11, characterized in that the anchoring pins screws ( 21 ) or bayonet locking pins. Peltier cooling device according to one of the preceding claims, characterized in that at least one of the heat exchangers ( 9 . 14 ) a cavity ( 31 . 37 ), which contains a heat transfer fluid simultaneously in the liquid and in the gaseous phase. Peltier cooling device according to claim 13, characterized in that in the cavity ( 31 . 37 ) filled heat transfer fluid has a saturation vapor pressure of 0.8 to 1.5 bar under normal operating conditions of the cooling device. Peltier Cooler according to claim 13 or 14, characterized in that the heat transfer fluid a saturation vapor pressure of less than 6 bar at 50 ° C having. Peltier cooling device according to claim 13, 14 or 15, characterized in that the cavity ( 31 . 37 ) on an inner wall with a porous layer ( 32 ) is provided, in which heat transfer fluid rises by capillary effect. Peltier cooling device according to claim 16, characterized in that the porous layer ( 32 ) at one of the Peltier element ( 17 ) facing away from the inner wall of the cavity ( 31 ) is attached. Peltier cooling device according to one of the preceding claims, characterized in that the carrier part ( 1 ) is injected in one piece from plastic. Refrigerating appliance with a heat-insulating housing surrounding an interior, characterized by a Peltier cooling device according to one of the preceding claims, in which an insulating layer ( 26 ) of the housing between the heat exchangers ( 9 . 14 ). Refrigerating appliance according to claim 19, wherein the Peltier cooling device is a cooling device according to one of claims 3 to 6, the sleeve ( 3 ) in the insulation layer ( 26 ) is embedded. Refrigerating appliance according to claim 19 or 20, wherein the Peltier cooling device is a cooling device according to one of claims 13 to 17, characterized in that the at least one a hollow space ( 31 ) having heat exchanger ( 14 ) is arranged in the interior of the refrigerator.