DE102018127928A1 - Heat transport unit - Google Patents

Abstract

The invention relates to a heat transport unit (1), which is designed in particular as a flexible heat pipe, with an evaporation area (2) and with a condensation area (3) and a line area (4) arranged between the evaporation area (2) and condensation area (3), via which thermal energy is transported from the evaporation area (2) to the condensation area (3), and with a fluid (14) located in the evaporation area (2), the line area (4) consisting of two connecting lines and vaporized fluid (14 ') via one of the two connecting lines. ) from the evaporation area (2) to the condensation area (3) and the other of the two connecting lines serves as a return line for condensed fluid (14).

Description

The invention relates to a heat transport unit, which is designed in particular as a flexible heat pipe, according to the preamble of claim 1.

State of the art

Heat pipes are also known under the term "heat pipes". Such heat pipes have an evaporation area where a fluid is evaporated by the application of heat. The vaporous fluid passes through a pipe section to a condensation area, where the vaporous medium is cooled and brought back into the liquid state. The cooled fluid is led back to the evaporation area via a capillary structure, so that there is a constant heat transport circuit from the evaporation area to the condensation area. Such a heat pipe is from the DE 10 2010 003 893 A1 known.

From the DE 10 2009 010 897 A1 A control cabinet with a plurality of switching devices arranged in the interior of the control cabinet is known, in which control cabinet components are cooled by means of heat pipes. In the prior art, heat pipes are used, for example, to cool microprocessors in device cabinets, it being possible for several computer units with microprocessors to be used as device racks in one device cabinet. The cooling in the individual plug-in units can be done quietly and very effectively by using heat pipes, whereby large amounts of heat energy can be dissipated from the inside of the device via the heat pipes. There is no need to use fans, which not only helps to avoid fan noise, but also has the great advantage that fan vibrations in the area of the sensitive electronic components are avoided.

Heat pipes can also be used to transfer heat from an evaporation area to a condensation area against gravity, since the capillary action enables the fluid to be transported back from the condensation area to the evaporation area against gravity. In contrast, there are also heat pipes that are operated by gravity, with the fluid flowing back from the condensation area to the evaporation area due to gravity.

The use of heat pipes is extremely versatile and is in no way limited to applications in the field of micro or power electronics. LED components, rechargeable high-performance batteries or other elements with high heat loss can also be effectively cooled using heat pipes. It is desirable that the circulation circuit between the evaporation area and the condensation area has the highest possible circulation speed, i. H. that as much fluid as possible is transported from the evaporation area to the condensation area and back to the evaporation area per unit of time, whereby an improvement in the heat transfer from the evaporation area to the condensation area is achieved.

The invention has for its object to provide a tubular heat transport unit that has the function of a heat pipe with the highest possible heat transfer performance.

The solution to this problem is obtained with the features of claim 1. The heat transport unit, which has the function of a heat pipe and has an evaporation area and a condensation area connected to it via a line area, has a line area which consists of two connecting lines, one via of the two connecting lines evaporated fluid from the evaporation area to the condensation area and condensed fluid flows back to the evaporation area via the other connecting line. The use of two connecting lines between the evaporation area and the condensation area has the advantage that the cooled fluid flowing back does not get impaired in its flow rate by the evaporated fluid flowing to the condensation area. Tests have shown that with this arrangement a high circulation speed and thus a very effective heat transfer from the evaporation area to the condensation area of the heat pipe can be achieved.

It is particularly advantageous to design the connecting lines between the evaporation area and the condensation area as a flexible double hose line, which preferably consists of an outer hose and an inner hose running in the outer hose. But it can also be one of two flexible, e.g. B. existing side-by-side hose lines can be used, in which case the evaporation area and the condensation area can each be formed as a chamber with two hose connectors.

Such a line connection has the great advantage that the heat transport unit can be easily positioned on the elements of a computer or other device to be cooled, position tolerances being completely unproblematic due to the flexibility of the heat transport unit are. Assembly problems, as can occur with the conventional rigid copper heat pipes, are avoided with the flexible heat transport unit according to the invention.

In the heat transport unit, a capillary structure can be provided on the inner wall in the connecting line serving as a return line, whereby a return transport of the cooled fluid to the evaporation area can be supported.

Since the connecting lines do not always have exactly the same flow resistance, the vaporized fluid will preferably use one of the two connecting lines during the evaporation process, so that this results in a fluid circuit in the heat transport unit. So that a specific connection line is used for the transport of the evaporated fluid and the other connection line for the backflow of the cooled fluid, a flow resistance element can be arranged in the transition area between one of the two connection lines and the evaporation area. This flow resistance element has the effect that gas bubbles rising during the evaporation process do not use the connecting line with the flow resistance element, but instead use the connecting line which is further open for the rising gas bubbles. In this way, for example, an inner hose concentrically located in an outer hose can be used for transporting the evaporated fluid to the condenser, so that the cooled fluid flows back from the condensation area through the space between the inner hose and outer hose to the evaporation area.

According to a development of the invention, the cross-sectional area of the connecting line provided for the forwarding of the vaporized fluid from the evaporation area to the condensation area can have a larger cross-sectional area in the transition area from the evaporation area to the connecting line than the connecting line provided for returning the condensed fluid in this transition area. This also ensures that ascending gas bubbles predominantly get into the connecting line, which has a larger cross-sectional area, during the evaporation process, so that a connecting line for the transport of the fluid to the condensation area can also be specifically specified thereby. The other connecting line is then inevitably used as a return line for the condensed and cooled fluid.

The evaporation area and the condensation area can advantageously consist of a plastic material with high thermal conductivity, wherein a high thermal conductivity can be achieved by using additives with high thermal conductivity. Depending on the area of application of the heat transport unit, the evaporation area and the condensation area can e.g. B. can also be formed as a copper tube closed on one side, the connecting lines then being connected to the open sides of these elements.

The fluid used in the heat transport unit preferably has a low boiling temperature, which can be, for example, at a pressure within the heat transport unit of 1 to 3 bar in a range between 25 ° Celsius and 40 ° Celsius. Depending on the area of application of the heat transport unit, fluids can also be used which have a higher or lower boiling point, which can be between -20 ° Celsius and + 1000 ° Celsius at a pressure of 0.001 to 100 bar.

Such a fluid is, for example, under the trade name Novec 7000 known. A low boiling temperature has the advantage that even with low heat development in the area of a component to be cooled, the heat transport and thus the cooling process can be used effectively.

The connecting line provided for the transport of the vaporized fluid can protrude slightly into the space of the evaporation area and protrude deeply into the space of the condensation area. The functionality of the heat transport unit is positively supported both in the evaporation area and in the condensation area.

The capillary structure formed on a connecting line can be produced in the extrusion process during the production of the connecting line. This results in a very inexpensive production for the connecting line equipped with capillary action.

There is also the possibility of inserting a longitudinal wick or a corresponding other element into the space between an outer tube and an inner tube, which has a capillary effect and thus supports a return transport of the cooled fluid from the condensation area to the evaporation area in this space.

The invention will be explained in more detail with reference to exemplary embodiments shown in the drawing.

• 1 eine Wärmetransporteinheit mit einer flexiblen Doppelschlauchleitung,
• 2 eine Wärmetransporteinheit wie bei 1, jedoch mit einem Strömungswiderstandselement im Übergangsbereich zwischen der Doppelschlauchleitung und einem Verdampfungsbereich,
• 3 eine vergrößerte Darstellung eines Teilbereichs der Wärmetransporteinheit von 2 im Bereich des Strömungswiderstandselements,
• 4 einen Querschnitt einer Doppelschlauchleitung mit einer Kapillarstruktur,
• 5 einen Längsschnitt entlang der Schnittebene A-A von 4,
• 6 einen Querschnitt einer Doppelschlauchleitung mit einem Dochtelement,
• 7 ein Längsschnitt entlang der Schnittebene B-B der Doppelschlauchleitung von 6 und
• 8 eine schematisch dargestellte Anordnung von zwischen Thermokopplungseinheiten wirksamen Wärmetransporteinheiten.

Show it:

• 1 a heat transport unit with a flexible double hose line,
• 2nd a heat transport unit like in 1 , but with a flow resistance element in the transition area between the double hose line and an evaporation area,
• 3rd an enlarged view of a portion of the heat transport unit of 2nd in the area of the flow resistance element,
• 4th 2 shows a cross section of a double hose line with a capillary structure,
• 5 a longitudinal section along the section plane AA from 4th ,
• 6 3 shows a cross section of a double hose line with a wick element,
• 7 a longitudinal section along the section plane BB the double hose line from 6 and
• 8th a schematically illustrated arrangement of effective heat transport units between thermal coupling units.

In the 1 heat transport unit shown 1 has the functionality of a heat pipe and has an evaporation area 2nd as well as a condensation area 3rd that have a line area 4th are connected to each other for the transfer of thermal energy. The evaporation area 2nd can consist of a metal sleeve closed on one side, for example made of copper. The condensation area 3rd can also be made from a metal sleeve closed on one side. But there is also the possibility of the evaporation area 2nd and the condensation area 3rd made of a plastic material 5 with the best possible thermal conductivity. In the following description, examples for the evaporation area are therefore exemplary 2nd and the condensation area 3rd used sleeves as plastic sleeves 6 , 7 designated.

The management area 4th is in the illustrated embodiment of a double hose 8th formed from an outer tube 9 and one in the outer tube 9 concentric inner hose 10th consists. Because an exact concentric arrangement of the outer hose 9 and inner tube 10th are not mandatory are in 1 no centering elements shown, but in the form of the inside of the outer tube 9 protruding centering bars could be present. There could also be intervals in the flexible double hose 8th annular centering elements can be used.

The double hose line 8th consists of a flexible plastic material, so that the heat transport unit 1 at least in the management area 4th can be bent flexibly and thus the evaporation area 2nd and the condensation area 3rd can be brought into different positions or orientations. In 1 is a heat source to be cooled 11 indicated as a circular area with broken lines, while a heat dissipation area 12th is also indicated with a broken circular line. The heat dissipation area is located 12th at a different position than the one shown, it is due to the flexible double hose line 8th possible that the heat transport unit 1 can be bent so that the condensation area 3rd forming plastic sleeve 7 with the heat dissipation area 12th can be brought into thermal contact. The heat dissipation area 12th can have an element with aluminum cooling fins or also an element through which a coolant flows.

The function of heat transfer will now be described below.

With that from the heat source 11 emitted heat energy is in the evaporation area 2nd in the plastic sleeve 6 located fluid 14 warmed and evaporated. The vaporous fluid 14 ' passes through the inner tube 10th according to the direction of the arrow 15 to the condensation area 3rd which is at a lower temperature so that the vaporized fluid 14 ' in the condensation area 3rd on the inner wall of the plastic sleeve 7 condensed and according to the direction of the arrow 16 again as a fluid 14 to the evaporation area 2nd flows back. As long as the heat source 11 continue thermal energy according to the directions of the arrows 13 the evaporation area 2nd feeds and in the condensation area 3rd a condensation takes place, a circulation cycle according to the directions of the arrow 15 , 16 maintained and thus a constant heat transfer from the heat source 11 to the condensation area 3rd or to a heat emission area 12th carried out.

As a fluid 14 low boiling point liquids are suitable which are generally known for such applications in heat pipes or heat pipes. Very good heat transfer results were achieved with a fluid that had a boiling point at approximately 30 ° Celsius. The boiling point of the fluid used 14 can be set to different heights depending on the area of application in different heat transport units, wherein a range between 25 ° Celsius and 80 ° Celsius can be provided, for example, as the boiling point for a given application. The boiling point of the fluid 14 can also be achieved by varying the internal pressure in the heat transport unit 1 Set, which can be, for example, 1 to 10 bar.

The heat transport unit 1 can be made with a length of less than 2 cm or also with a length of more than 1 m, with diameters from less than 1 mm to over 10 mm depending on the application. For a flexible heat transport unit 1 with a diameter of 10 mm, a heat transfer with a heat output of 1200 watts can be achieved, namely at a temperature difference of 10 ° C between the evaporation area 2nd and the condensation area 3rd . The end pieces, ie the plastic sleeves 6, 7, of the heat transport unit 1 can according to 8th with thermocouple units designed as metal blocks 31 be connected in a heat-conducting manner, for example in that the end pieces in bores 51 of these thermal coupling units 31 are plugged in. These thermocouple units 31 can then use heat sources - for example a microprocessor 32 - or on the other hand with cooling devices 33 be connected in a heat-conducting manner to implement a heat transport system. In the 8th Arrows show an example of the transport direction of the heat transfer via the heat transport units 1 .

In 2nd is a version of the heat transport unit 1 according to 1 specified, but in addition, a flow resistance element 17th than one on the plastic sleeve 6 inwardly projecting ring edge is provided. The ring edge can also be referred to as a ring bead and serves to ensure that in this transition area between the evaporation area 2nd and the management area 3rd the cross section for the backflow of the fluid 14 is concentrated. This ensures that the vaporized fluid 14 ' prefers the way through the inner tube 10th chooses according to the direction of the arrow 15 . It is important that the flowing back condensed fluid is not too strong at the return flow in the direction of the arrow 16 to the evaporation area 2nd is prevented. The same also applies to a similar flow resistance element 18th at the transition area between the line area 4th and the condensation area 3rd .

The two flow resistance elements 17th , 18th also serve as centering elements for the inner hose 10th , so that it is at least in the transition areas approximately concentric with the outer tube or the plastic sleeves 6 , 7 is arranged. The flow resistance elements 17th , 18th can very advantageously also be designed as knobs, which the inner tube lying between them 10th fix in position. There may be free spaces between the individual knobs through which the fluid flowing back 14 according to the direction of the arrow 16 from the condensation area 3rd to the evaporation area 2nd can flow back.

In 1 and 2nd is the heat transport unit 1 about half each with fluid 14 filled. The fill level can be selected differently depending on the area of application and the fluid used. Good circulation properties were achieved at a fill level of 30% to 50% of the available volume. Depending on the fluid used and depending on the area of application, other fill levels may be appropriate.

3rd shows a longitudinal section of the heat transport unit 1 from 2nd in the evaporation area 2nd . By supplying heat in the direction of the arrow 13 over the plastic sleeve 6 to the fluid 14 becomes the fluid 14 heated so that an evaporation process takes place. This causes bubbles to rise 20th in the fluid 14 on what is indicated by single arrows. Because the effective cross-section of the inner tube 10th is greater than that for the backflow according to the direction of the arrow 16 provided line cross section, the fluid evaporates 14 over the inner tube 10th and also gets through the inner tube 10th to the condensation area 3rd ( 1 , 2nd ).

In 4th is a version of a double hose line 8th shown, in which the outer hose 9 a capillary structure on its inner wall 21st that extends the entire length of the outer tube 9 extends. The broken circular line indicates that the capillary structure 21st can extend over the entire circumference on the inner wall. 5 shows the longitudinal section of the in 4th shown arrangement.

6 and 7 show a cross section and a longitudinal section of a double hose line 8th with an inserted wick element extending over the entire length 22 . The wick element extends here as an example 22 only over a sub-segment of that for the backflow from the condensation area 3rd to the evaporation area 2nd provided space 23 . Basically, the wick element 22 also the space 23 fail completely. The wick element 22 and the capillary structure 21st ( 4th , 5 ) can help support the reflux of the condensed fluid.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 102010003893 A1 [0002]
• DE 102009010897 A1 [0003]

Claims (11)

Heat transport unit (1), which is in particular designed as a flexible heat pipe, with an evaporation area (2) and with a condensation area (3) and a line area (4) arranged between evaporation area (2) and condensation area (3), via the thermal energy from the evaporation area (2) is transported to the condensation area (3), and with a fluid (14) located in the evaporation area (2), characterized in that the line area (4) consists of two connecting lines and that vaporized fluid (14 ') from the evaporation area (2) to the condensation area (3), and that the other of the two connecting lines serves as a return line for condensed fluid (14). Heat transport unit (1) after Claim 1 , characterized in that the connecting lines form a flexible double hose line (8) consisting of an outer hose (9) and an inner hose (10) running in the outer hose (9). Heat transport unit (1) after Claim 1 , characterized in that the return line has a capillary structure (21) on its inner wall. Heat transport unit (1) according to one of the preceding claims, characterized in that at least one flow resistance element (17) is arranged in the transition region between one of the two connecting lines and the evaporation region (2). Heat transport unit (1) according to one of the preceding claims, characterized in that the cross-sectional area of the connecting line provided for the transmission of the vaporized fluid (14 ') from the evaporation area (2) to the condensation area (3) is larger at least in the transition area from the evaporation area (2) to the connecting line is the cross-sectional area of the connecting line provided for the return of the condensed fluid (14) from the condensation area (3) to the evaporation area (2) in this transition area. Heat transport unit (1) according to one of the preceding claims, characterized in that the evaporation area (2) and the condensation area (3) consist of a material with high thermal conductivity. Heat transport unit (1) after Claim 6 , characterized in that the material is a plastic material with additives that increase the thermal conductivity. Heat transport unit (1) according to one of the preceding claims, characterized in that the fluid (14 ') has a low boiling temperature, which is at a pressure of 0.001 to 100 bar in a range between -20 ° Celsius and + 1000 ° Celsius. Heat transport unit (1) according to one of the preceding claims, characterized in that the connecting line provided for the transmission of the vaporized fluid (14 ') projects slightly into the space of the evaporation area (2) and deep into the space of the condensation area (3). Heat transport unit (1) according to one of the preceding claims, characterized in that a capillary structure (21) is produced on an inner wall of one of the connecting lines in the extrusion process. Heat transport unit (1) according to one of the preceding claims, characterized in that the heat transport unit (1) is used for cooling electronic components, in particular microprocessors, in an electrical device.

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