DE4020859A1 - Heat accumulator mfr. process - with component protection during baking or evacuation of insulation area - Google Patents

Abstract

The process is esp. for the mfr. of a latent heat accumulator for vehicle heating systems supplied by engine waste heat. It has a double casing (10), enclosing an insulation area; an accumulator core; and an inlet and outlet for the heat carrier, connected to a flow path. After mechanical fabrication of the casing, the insulation area is baked for degasifying, and evacuated. Baking takes place at a temp. above the operational temp. of the heat exchanger, and the components of the accumulator core are protected against temp. dependent damage. USE - Latent heat accumulator for vehicle.

Description

The invention relates to a method for manufacturing a heat store, in particular a latent heat memory for motor vehicles fed by waste heat from the engine Stove heaters, with a housing that an outside container and one spaced from it Contains inner container, the Iso between them Enclosure area, with one in the inner container arranged memory core in which at least one Chamber for a storage medium through a partition of at least one flow path for a heat carrier is separated, and with an inflow line and a drain line for the heat transfer medium, with the Flow path in connection and through the Iso lierbereich are led to the outside, the Iso area after the mechanical completion of the Housing for degassing is heated and evacuated, as well as a heat store for performing the Ver driving.

In the case of vehicle heaters, it is desirable that the heat can be saved overnight to start at Vehicle in the morning on sufficiently stored To have heat until the engine cooling water reaches its Has reached operating temperature. Taking into account compliance with the usual requirements in vehicle construction low weight and volume, he can do this required insulation quality of the heat storage only through double-walled housing can be achieved, the Spei enclose the core of the core on all sides and in your dop  pelt wall have an insulating vacuum. It can be a high vacuum, or insulation from microporous materials, such as. B. Powders or fibers that are also evacuated. There are therefore housings with an outer container and an inner container used, between the an insulating area is provided for both containers, that of the inflow line and the outflow line for is passed through the heat transfer medium, whereby Wärmver loss through convection and heat conduction of the heat transfer gers, e.g. B. the engine cooling water or the engine exhaust can be caused. A heat storage with one such insulation is for example from DE OS 36 14 318 known.

The high insulation quality of such heat storage is based on one on the application of vacuum technology, which since is known for a long time, and on the other hand on the closed design of the insulating vessel from outside and Inner container, causing heat conduction through hard body on the inlet and outlet line and on the Storage of the inner container in the outer container be is restricted. The heat conduction via the inlet and outlet River pipe can be trained by small Cross-section and long distances kept relatively small will.

After the mechanical completion of one Storage housing is the desired insulating effect by evacuating the isolation area within a few minutes away. This isolating effect is but not in existence because of the isolation richly facing surfaces of the exterior and exterior Inner container, on the surfaces of if necessary radiation shields located in the isolation area or  micro-porous insulating materials, as well as on the non avoidable built-in parts in the insulation area, namely the inlet and outlet pipes and the storage of the Inner container, substances that can be absorbed in the Evaporate over time, causing the pressure in the iso lier range increase and thus the insulating effect of the Remove vacuum.

For this reason, vacuum-insulated vessels are used mechanical production over a long period guest, the insulation area being constantly pumped out becomes. For example, the duration of the degassing To reduce 24 hours, the vacuum flask is at the degassing brought to an elevated temperature, what is called baking. According to experience causes a temperature increase of 10 ° C halving the degassing time.

It is also known to be a major contaminant water deposited on the walls by vacuum vessels is. For water removal there are three Embossed temperature levels, namely approx. 120 ° C with low evaporation rates, 180 ° C with very high Evaporation rates and about 360 ° C with practically hun % evaporation.

It is also known that the degassing Long-term effect from the lowest temperature depends on the surfaces in the insulation area is aimed. It follows that for a particular Long-term effect all facing the isolation room Surfaces reach or exceed the minimum temperature have to walk.  

For large-scale application in motor vehicle construction a long-term effect of the vacuum is required, the at least one heating in the area of the second Levels of 180 ° C required. The operating temperature for heat storage of this type, however, is 90 ° C with a maximum required temperature of 125 ° C. Which is required when creating a good vacuum Liche baking temperature is therefore much higher than the operating temperature to be expected later. This results in the problem of thermal damage heat storage in the manufacturing process, for example, by using increased vapor pressure storage media, through degradation of load-bearing Parts in the storage core, for example plastics, through thermal expansion and the like.

The invention has for its object a method for the production of heat storage gangs mentioned design so that without tem temperature-related damage in an under economic considerable aspects, significantly ver high quality insulation can be created, especially for the An persistence sufficiently long in motor vehicles dig is. In addition, a heat storage device is designed in this way be that he uses the application of the allowed method according to the invention.

The solution to the problem is that the heating with a much higher than the loading operating temperature of the heat storage tem temperature takes place and the temperature sensitive Components of the memory core against temperature-related Damage is protected.  

The type of protection for the temperature sensitive Components of the memory core depends on the Kind of possible damage to the memory core that on the one hand, as explained above, directly due to the heat sensitivity of the mate used rialien and / or due to material stress through thermal expansion of the mechanical components of the Storage core or due to excessive steam pressure in the food can result.

An expedient embodiment of the invention be is therefore that at least during the off heating of the memory core in relation to the insulation area is heat insulated, according to further advantageous Embodiments an isolation space between the Spei core and the inner container at least during the Heating the insulation area either with a gas low thermal conductivity filled or evacuated is.

Another expedient embodiment is that during the heating of the isolation area on the partitions of the Kam containing the storage medium acting, excessive vapor pressure of the storage space diums is supported, according to an appropriate Design during the bake out of the inflated Static compensating vapor pressure of the storage medium Pressure built up in the flow paths in the inner container becomes.

According to another appropriate training while heating the inner container with a Filled liquid whose temperature dependent Vapor pressure curve is selected so that it is the steam pressure of the storage medium during baking  compensated, this liquid during the Heating in the inner container hermetically sealed becomes. The inner container is preferably included Filled with ethylene glycol.

There is still another practical embodiment in that a cooling medium during baking is passed through the flow path, the cooling medium, for example, a mixture of ethylene glycol and can be water.

In the case of a heat accumulator with an insulating gap, the between a lateral surface that the memory core between two end faces, in which the flow path leading through the storage core or opens out, and the inner container is, be is a further advantageous embodiment, that the flow of the cooling medium through the insulation gap between the two end faces blocked becomes, whereby the flow prevented from flowing medium warms up and an undesirable cooling of the inner container prevented during baking.

Another, very advantageous embodiment be stands for a heat accumulator with an insulating gap, which is between a lateral surface that the Spei core between two faces in which the flow path leading through the storage core or empties, and the inner container is there rin that the cooling medium in the range of the operating temperature of the heat accumulator heated up and then during the baking in this Temperature range is maintained. As a result, the ge Desired bakeout temperature reached faster and  excessive cooling of the Inner container prevented.

The evacuation of the isolation area represents one expensive measure, which is why it is desired is to increase the duration of this process as much as possible restrict. An advantageous further embodiment is therefore that the memory core first with a flow medium serving as a heat transfer medium to the maximum permissible temperature for the memory core preheated and then until the end of Bakeout process held at this temperature level becomes.

The flow medium is used until the desired temperature levels as heating medium and after that, until the end of the heating process at one the maximum allowable temperature of the storage bake-out temperature exceeding the core as cooling dium.

Another useful embodiment is that the evacuation of the isolation area with time Delay compared to preheating the food core begins, being particularly beneficial if, according to a further preferred embodiment form of storage with preheated storage core fed to a heating station and there the insulation area is heated and evacuated.

A heat accumulator is used to carry out the method with a housing that has an outer container and a spaced from this inner container includes an isolation area between them close with one arranged in the inner container  Storage core in which at least one chamber for one Storage medium through a partition of at least a flow path for a heat transfer medium separated is, and with an inflow pipe and a drain pipe for the heat transfer medium, with the flow path communicate and through the isolation area are guided to the outside, designed such that the Storage core at a distance from the inner wall of the Inner container is stored and the space between the Inner container and the storage core with the flow away communicates. This makes it possible speed, while heating the space between the Inner container and the memory core over the after leading outside, when operating the heat exchanger Flow path in the storage core with the heat transfer medium supplying line connection with a thermal insulation charging gas or evacuating this room ren. But it can also during baking, at for example using the heat insulating Gases, a static pressure in the flow paths be built up, which occur when baking out compensate for the increased vapor pressure of the storage medium siert. Finally, there is also the possibility during baking out via the cable connection the flow path with a liquid, such as Ethylene glycol, to be filled, the temperature-dependent ger steam pressure curve is selected so that it the Vapor pressure of the storage medium during baking compensated.

The storage core is preferably above supporting elements from heat-insulating and in the area of the heated temperature-resistant material on the inner container ter supported.  

According to a further advantageous embodiment, mun the inlet and outlet pipes in the inner container ter, in which on opposite sides of the Memory core, through which the memory core through flowing flow paths, each between a collecting space for the inner container and the storage core is kept free for the heat transfer medium.

Another advantageous embodiment consists of Heat storage, in the storage core, the chamber for the storage medium into a number of through the Flow path for the heat transfer medium separated from each other te, enclosed by thin partitions and one sub-chambers with a flat cross-section is sharing, the long cross-sectional sides of each other are facing in that the distance of this flat Cross-sectional sides of adjacent subchambers like this is dimensioned that these cross-sectional pages under the influence of the cross section of the subchambers increasing steam pressure when baking each other out support before stretching the walls of the part a safety limit.

Another useful embodiment is at a heat accumulator, in whose storage core the Kam mer for the storage medium in a number of part chambers and the flow path into a number of themselves channels extending between these subchambers is divided, the channels and the subchambers are separated from each other by thin partitions, in that the partitions by spacers are connected to each other, whereby by increased Forces caused by vapor pressure and / or thermal expansion can be supported. After an expedient The spacers are tensile with the design  Partition walls connected and can therefore also one support increased vapor pressure in the room in which the Spacers are arranged.

Especially when the currents are baked out path for the heat transfer medium from a cooling medium is flowed through, there is another advantageous Design in that the spacers in the channels for the heat transfer medium are arranged. The heat absorption of the coolant increases it Vapor pressure, so that the vapor pressure of the cooling by means of the thin partitions between the channels and endanger the partial chambers for the storage medium can. The under the influence of the vapor pressure in the cooling forces acting on the partition walls absorbed as tensile forces by the spacers.

An advantageous embodiment is that the memory core is surrounded by a core jacket is supported on the inner container.

According to a further expedient embodiment instructs the core jacket between two end faces where the channels belonging to the flow path open, an outer surface that forms an iso lierspäß the outer surface of the inner container ge opposite, this insulating gap for permanent insulation with a microporous Insulation material can be filled. Preferably the isolation gap is at least with one of the Collection rooms in connection to one of the cooling of the Storage coolant serving the inflow or Allow flow. Is the isolation gap only that comes in connection with one of the collecting rooms Coolant in the insulating gap to a standstill and warmed up  itself, which in the manner already described Cooling of the inner container is prevented.

Based on the following description of the in the Drawing illustrated embodiments of the Invention this is explained in more detail.

It shows:

Fig. 1 is a schematic longitudinal section through a latent heat storage for automotive heating tongues, which is suitable for performing the method according to the Invention, and

Fig. 2 shows a cross section through this cher thermal storage according to a first embodiment;

Fig. 3 shows the same cross section in another embodiment and

Fig. 4 is a detail view to FIG. 2.

The heat accumulator shown has a housing, identified overall by 10 , consisting of an outer container 12 and an inner container 14 arranged at all sides from the outer container 12 , wherein, for simplification of the illustration, position elements for supporting the inner container 14 in the outer container 12 to form an insulating vessel are not shown. In the inner container 14 , a memory core 16 is arranged, in which the Speicherbe rich 18 for the heat storage medium is crossed by a number of channels 20 running parallel to one another for a heat transfer medium, the arrangement being made such that the channels 20 on two opposite ends 22 and exit 24 of the core enclosed by a jacket 26 memory core 16, and there in each case open out into collecting chambers 28 and 30 for the heat carrier.

Figs. 2 and 3 show two different shapes of the exporting approximately enclosed by the core shroud 26 SpeI cherkerns sixteenth

In the variant according to FIG. 2, the Kernman tel 26 encloses a group of flat, parallel to one another and to form the channels 20 spaced from one another, filled with the heat-storing medium partial chambers 18 a.

The sub-chambers 18 a are separated from the thin-walled, almost no pressure deformable walls 38 opposite the channels 20, wherein only indicated once in the channels 20 are disposed with 40 designated, and in Fig. 4 clearly shown spacers, with the partition walls 38 and on the edge of the memory core 16 are firmly connected to the core jacket 26 . In addition to the improvement in mechanical strength which will be explained below, the spacers 40 also serve the purpose of generating turbulence when a medium flows through the flow path.

The sub-chambers 18 a having a flat cross section, for example in the form of flattened ovals or rectangles, with opposite long sides of the cross sections be nachbarter sub-chambers 18 a to each other.

The embodiment according to FIG. 3 differs from the embodiment according to FIG. 2 in that a uniform chamber 18 b is provided for the heat-storing medium, which is closed by the core jacket 26 . In the interior of the chamber 18 , which is filled with the storage medium, the channels 20 are delimited by membrane-like, tubular, through not shown Darge spacers or support elements in a flat cross-sectional shape with spaced walls 21 .

The flow path formed by the plenums 28 and 30 and the channels 20 for the heat transfer medium in the memory core 16 is connected to an inflow line 32 and a return line 34 which open into the inner container 14 , either the inflow line 32 in one and the Return line 34 in the other ren collecting space 28 and 30 , as shown, or both lines in one of the two collecting spaces, which is then divided into an inflow and a reflux chamber under and then the other collecting space serves as a deflection chamber for the heat transfer medium .

Between the two end faces 22 and 24 , the core jacket 26 has a lateral surface 35 , which extends ge parallel distance parallel to the opposite man telfläche 37 of the inner container 14 , so that an insulating gap 39 is formed between the two lateral surfaces 35 and 37 , which stores the heat Medium in the memory core 16 protects against overheating when baking out.

In the variant of FIG. 2, the core jacket 26 and thus also the jacket surface 35 need not be closed, so that the insulating gap 39 forms part of the flow path for the heat transfer medium.

In the case of a closed design of the core jacket 26 , as is required in the variant of the memory core 16 according to FIG. 3, but can also be used in the variant according to FIG. 2, the insulating gap 39 can be closed. However, it can also be open towards the collecting spaces 28 and 30 and thus also form part of the flow path for the heat transfer medium. The insulating gap 39 can, however, also be filled with a microporous material in order to form permanent insulation between the inner container 14 and the storage core 16 .

Between the outer container 12 and the inner container 14 there is an insulating region 36 which contains a vacuum or is filled with microporous substances and is additionally evacuated. This insulating region 36 is traversed by the inflow line 32 and the return flow line 34 , which ends outside of the outer container 12 .

Between the core jacket 26 and the inner container 14 , support or storage elements 42 made of sufficiently heat-resistant and preferably thermally insulating material are arranged.

After the complete assembly of the above-described heat accumulator, the above-described heating and evacuation of the insulating region 36 is carried out for permanent thermal insulation of the memory core 16 , for which purpose the complete heat accumulator is introduced, for example, into the furnace for the intended heating time.

To protect the storage core 16 , for example, the flow path and thus also the space forming an insulating space between the inside of the inner container 14 and the outside of the core jacket 26 can be filled with a heat-insulating gas or with a liquid, such as ethylene glycol, the temperature-dependent vapor pressure profile of which compensates the vapor pressure in the storage medium during baking. But it can also be generated in the flow path, a heat-insulating vacuum, where appropriate, the inflow line 32 and the return line 34 must be hermetically sealed.

If the subchambers 18 are deformed by an increased vapor pressure of the storage medium, another adjacent partition 38 can be supported against one another.

However, a cooling medium, such as a mixture of water and ethylene glycol, can also circulate through the flow path in order to keep the insulation space at a temperature which does not exceed the operating temperature. It is possible to heat the cooling medium before starting the heating and evacuation, for example, to this desired temperature of 120 ° C, so that in the initial phase of heating the inner container 14 and thus the inner boundary of the insulating area 36 is also heated from the inside and thereby faster reach the bakeout temperature. If subsequently the cooling medium is kept at this temperature of, for example, 120 ° C. by the heat to be dissipated, the storage core is protected against harmful heat. However, the cooling medium mentioned at a temperature of 120 ° C. has a vapor pressure of 2 bar, which the partition walls 38 alone could not withstand. The forces acting on the partition walls 38 are therefore absorbed by the spacers 40 as tensile forces.

A variant, not shown, is that the insulating gap 39 is separated from one of the plenums 28 or 30 , whereby a flow through the insulating gap 39 is prevented while the cooling medium flows through the channels 20 through the storage core and maintain the desired low temperature can. In contrast, the cooling medium standing in the insulating gap 39 can heat up and thus prevent undesired cooling of the inner container 14 .

A particularly economical way of producing heat memory is achieved when you look at the memory core e.g. B. at a preheating station to its maximum preheated temperature and then the heat storage to a heating station, where the insulation area brought to the baking temperature and evacuated becomes.

Claims (27)

1. A method for producing a heat accumulator, in particular a latent heat accumulator for motor vehicle heaters fed by engine waste heat, with a housing which comprises an outer container and an inner container arranged at a distance therefrom, which enclose an insulating area between them, with a memory core arranged in the inner container, in which at least one chamber for a storage medium is separated by a partition from at least one flow path for a heat transfer medium, and with an inflow line and an outflow line for the heat transfer medium, which are connected to the flow path and are led through the insulating region to the outside, wherein the insulating area after the mechanical completion of the housing for degassing is heated and evacuated, characterized in that the heating takes place with a temperature substantially above the operating temperature of the heat accumulator and the components are te n of the memory core are protected from temperature-related damage. 2. The method according to claim 1, characterized characterized, characterized in that at least wäh rend of the storage core compared to the Isolation area is thermally insulated. 3. The method according to claim 2, characterized records that an isolation space between the memory core and the inner container at least during the off heating of the isolation area with a gas less Thermal conductivity is filled. 4. The method according to any one of claims 2 or 3, characterized in that an isolation space between the storage core and the inner container at least evacuated during heating of the insulation area is. 5. The method according to any one of claims 1 to 4, characterized in that during baking the insulation area of the inflated, on the partitions of the acting chambers containing the storage medium Vapor pressure of the storage medium is supported. 6. The method according to claim 5, characterized records that during the bake a the over increased vapor pressure of the storage medium  static pressure in the flow paths in the inner container ter is built. 7. The method according to claim 5, characterized records that during the heating of the inner container is filled with a liquid, the tempe rature-dependent vapor pressure curve is chosen so that he the vapor pressure of the storage medium during the Heating out compensates and that this liquid hermetically during baking in the inner container is completed. 8. The method according to claim 7, characterized records that the inner container during baking is filled with ethylene glycol. 9. The method according to claims 1 or 2, because characterized in that a during heating Cooling medium is passed through the flow path. 10. The method according to claim 9 in a heat storage cher with an insulating gap between one Lateral surface, the memory core between two forehead surrounds areas where the through the memory core leading flow path opens and ends, and the Inner container is located, characterized in that the flow of the cooling medium through the insulating gap is blocked between the two end faces. 11. The method according to claim 9 in a heat storage cher with an insulating gap between one Lateral surface, the memory core between two forehead surrounds areas where the through the memory core leading flow path opens and ends, and the Inner container is located, characterized in that  at the beginning of the heating, the cooling medium in the Be range of the operating temperature of the heat accumulator heated and then during baking in this Temperature range is maintained. 12. The method according to any one of claims 1 to 9, characterized in that the memory core first with a flow serving as a heat transfer medium medium to the maximum for the memory core permissible temperature preheated and then up to End of the heating process at this tempera level is maintained. 13. The method according to claim 12, characterized records that the evacuation of the isolation area with a time lag compared to preheating of the memory core begins. 14. The method according to claim 13, characterized records that the memory with preheated memory core of a heating station and there the Insulated area is heated and evacuated. 15. Heat accumulator for performing the method according to claim 1, with a housing ( 10 ) which comprises an outer container ( 12 ) and a spaced from this inner container ( 14 ), which enclose an insulating region ( 36 ) between them, with an in Inner container ( 14 ) arranged storage core ( 16 ), in which at least one chamber ( 18 ) for a storage medium is separated by a partition ( 38 ) from at least one flow path ( 20 ) for a heat transfer medium, and with an inflow line ( 32 ) and one Drain line ( 34 ) for the heat transfer medium, which are connected to the flow path ( 20 ) and are led out through the insulating area ( 36 ), characterized in that the storage core ( 16 ) is mounted at a distance from the inner wall of the inner container ( 14 ) . 16. Heat storage device according to claim 15, characterized in that the space between the inner container ( 14 ) and the storage core ( 16 ) is designed as a closed insulation space. 17. Heat storage device according to claim 15, characterized in that the space between the inner container ( 14 ) and the storage core ( 16 ) is in communication with the flow path ( 20 ). 18. Heat accumulator according to one of claims 15 to 17, characterized in that the storage core ( 16 ) is supported on the inner container ( 14 ) via support elements ( 42 ) made of heat-insulating and temperature-resistant material in the region of the baking temperature. 19. Heat storage device according to one of claims 15 to 18, characterized in that the inflow and the outflow line ( 32 , 34 ) into the inner container ( 14 ), in which on the mutually facing end faces of the storage core ( 16 ), at which the said memory core (16) by pulling the flow paths (20) open out, in each case cherkern between the inner container (14) and SpeI (16) a collection space (28, 30) is kept free for the heat carrier. 20. Heat storage in its storage core ( 16 ), the chamber for the storage medium is divided into a number of chambers ( 18 ) divided by thin flow walls ( 38 ) and a flat cross section through the flow path for the heat transfer medium from one another Long cross-sectional sides facing each other, according to one of claims 15 to 19, characterized in that the distance between these flat cross-sectional sides neighboring subchambers ( 18 ) is dimensioned such that these cross-sectional sides enlarge under the influence of the cross section of the subchambers ( 18 ) Support the vapor pressure against one another when baking out before the expansion of the walls ( 38 ) of the subchambers ( 18 ) exceeds a safety limit. 21. Heat store, in the storage core ( 16 ) of which the chamber for the storage medium is divided into a number of subchambers ( 18 ) and the flow path into a number of channels ( 20 ) extending between these subchambers ( 18 ), the channels ( 20 ) and the subchambers ( 18 ) are separated from one another by thin partition walls ( 38 ), according to one of claims 15 to 20, characterized in that the partition walls ( 38 ) are connected to one another by spacers ( 40 ). 22. A heat accumulator according to claim 21, characterized in that the spacers ( 40 ) are connected to the partition walls ( 38 ) in a tensile manner. 23. Heat accumulator according to one of claims 21 or 22, characterized in that the spacers ( 40 ) in the channels ( 20 ) for the heat transfer medium are angeord net. 24. Heat accumulator according to one of claims 15 to 23, characterized in that the memory core is enclosed (16) of a core shroud (26) which is supported on the inner container (14). 25. The heat accumulator according to claim 24, characterized in that the core jacket ( 26 ) between two end faces ( 22 , 24 ), on which the flow path associated channels ( 20 ) open out, has a lateral surface ( 35 ) which forms an insulating gap ( 39 ) of the outer surface ( 37 ) of the inner container ( 14 ) opposite. 26. Heat accumulator according to claim 25, characterized in that the insulating gap ( 39 ) is filled with a microporous insulating material. 27. Heat storage device according to claims 19 and 26, characterized in that the insulating gap ( 39 ) is at least connected to one of the collecting spaces ( 28 , 30 ).