EP1967799A2 - Sorption cooling element with regulating organ and additional heat source - Google Patents

Abstract

Cooling element is hermetically surrounded by a gas-tight multiple layer film to enclose a regulating unit (3), a steam passage (4) and a vaporizer (2). The vaporizer and the steam passage are flexible and the steam is only able to pass via the regulating unit to an absorbent (1). An independent claim is also included for a method for evacuating a cooling element. Preferred Features: The regulating unit contains a valve (6) which is operated by deforming the multiple layer film and a thermostatic valve. The thermostatic valve contains a regulating body made from a bimetal and is in thermal contact with the steam.

Description

The invention relates to a sorption cooling element with a control element and with a gas-tight multi-layer film for cooling in which by evaporation of a working fluid and subsequent sorption of the working medium vapor in a sorbent under vacuum cold generated. The evaporator is flexibly designed to be adapted to various cooling tasks.

Sorption cooling elements are devices in which a solid adsorbent sorbs a second, boiling at lower temperatures agent, the working medium, in vapor form with heat release (sorption). The working fluid evaporates in an evaporator while absorbing heat. After the adsorbent is saturated, it can be desorbed by supplying heat at a higher temperature (desorption phase). During this process, working fluid evaporates from the adsorbent. The working fluid vapor can be reliquefied and then re-vaporized.

Adsorption apparatus for cooling with solid sorbents are from EP 0 368 111 and the DE-OS 34 25 419 known. Sorbent container, filled with sorbents, thereby absorb working agent vapor, which is produced in an evaporator, and sorb it under heat release. The heat of sorption must be removed from the sorbent. The chillers can be used to cool and keep food warm in thermally insulated boxes.

The WO 01/10738 A1 describes a self-cooling beverage can with an evaporator inside and a sorber outside the can. The cooling is started by opening a steam channel between evaporator and sorber. The cold generated in the evaporator is discharged through the surfaces of the drink to be cooled within the can. The heat generated in the sorbent is stored in a heat buffer. The self-cooling beverage can is heavily modified over an ordinary can and expensive to manufacture.

Further, more theoretical embodiments of self-cooling containers are in the WO 99/37958 A1 compiled. Cost effective is none of the devices implement and manufacture.

The US Pat. No. 6,474,100 B1 finally describes a self-cooling cooling element on the outside of a bag for liquids or bulk materials. The sorbent is enclosed in a flexible, multi-layered film. The contact with the hot sorption filling is reduced to a minimum by insulation and flow materials as well as by intervening heat storage masses. The temperature compensation between the hot sorber filling and the cold evaporator, which are opposed over a large area, must be reduced by an elaborate insulation.

The DE 10 2005 034297 A1 describes a sorption cooling element with gas-tight film in which a sorbent is filled in a gas-tight sorbent bag, which is cut to start the cooling function by means of cutting tool. A regulation of the cooling capacity is not possible.

Object of the invention are inexpensive sorption cooling elements for single use in which the cooling is adjustable.

This object is achieved by the characterizing features of claims 1 and 24. The dependent claims show further inventive cooling elements.

According to the invention, the individual components of a cooling element are sealed in a gas-tight, flexible multi-layer film under vacuum so that the effluent from the liquid working fluid can flow only through the working medium vapor passage and the control element to the sorbent. The deformation forces generated by the external air pressure must be sufficient to nestle the multilayer film around the individual components in such a way that no sidestream remains open for the working medium vapor to bypass the control element. The individual components must therefore not be connected to each other gas-tight. They are only to be inserted into a bag made of the multilayer film and to be fixed until the bag settles firmly under vacuum around the components and only the working medium steam channel remains open.

According to the invention, the control element can be easily opened and closed by deforming the multilayer film. Elaborate vacuum feedthroughs are therefore not necessary.
Particularly advantageous, the control element can be formed from a valve seat and a matched sealing surface. By means of a lever mechanism, the regulating member can be opened and closed by the multi-layer film and, if necessary, also be used for power control.
In order to press the sealing surface onto the valve seat, no further spring elements are necessary if the flexible film rests on the sealing surface in such a way that the external air pressure can act suitably on the valve.

It is advantageous for the working medium steam ducts to use hoses that Although withstand the external pressure, but not an additional pressure, eg generated by a squeezing tool, which acts from the outside on the multi-layer film and squeezes the tube so strong that the flow path is blocked.
Another very inexpensive control organ is formed when the sorbent is sealed within a separate bag. If this bag is pierced at the point of contact with the working medium vapor channel by means of a sharp-edged cutting tool, the regulating member is likewise opened. Of course, the cutting tool can also be inserted between the multilayer film and the separate bag. For the triggering then the outer film must be deformable at the point in question without even be leaking.

The control element may be extended by a thermostatic valve in addition to the actual closure element. With the help of the thermostatic valve, the temperature of the evaporator can be maintained at a control temperature. At higher temperatures, the thermostatic valve releases the path of the working medium vapor to the sorbent, at too low temperatures, the thermostatic valve closes the way.
As a thermostat, all known elements that pull a change in temperature with a change in temperature are suitable. The most well-known here are stretchers and bi-metals. Memory alloys can also be used to advantage. Bi-metal spirals can be used particularly cost-effectively for the control element. This temperature variations of less than 0.1 Kelvin can be achieved.

By installing a thermostatic valve, the cooling elements can be used particularly advantageous for temperature-controlled cooling of transport isolation containers. Isolated transport containers serve e.g. for shipping temperature-sensitive food or pharmaceutical goods between +2 and +8 ° C. Equipped with cooling elements according to the invention, insulated transport containers are storable over an arbitrarily long period of time. To start the cooling function, only the control element has to be opened and the product to be cooled must be packed into the interior. The thermostatic valve then regulates the interior in a narrow temperature window, regardless of the prevailing outside temperature over several days. Since the insulating container can be made of inexpensive material (for example, polystyrene) can be dispensed with an often expensive return transport.

According to the invention, all inner walls of an insulating container can be covered with evaporator surfaces. The interior temperature is then very homogeneous even with strongly fluctuating outside temperatures. Since the evaporator is constructed flexibly according to the invention, at least one evaporator region can be made foldable. This area can be opened up if necessary and grant full access to the internal volume.

Under vacuum, all flow channels to the sorbent must be maintained. For this purpose, spacers are provided, which allow the working medium vapor flow freely from the liquid working fluid and at the same time contact the cold surfaces with good thermal conductivity of the film.
According to the invention flexible plastic spacers are used, which are adapted to the respective cooling task. However, the prerequisite is that the plastic spacers do not outgas during storage and worsen the vacuum. It is advantageous if polycarbonate, polyamide or polypropylene are used as the plastic, since these materials can be heated to higher temperatures and degassed before or during the production process.
Spacers made of plastic can be produced inexpensively by known manufacturing processes such as deep drawing, extrusion or thermal blasting. Advantageously, in the manufacturing process, it is important to ensure that no later outgassing substances such as plasticizers are added.

In today used thermal transport containers, the cargo is cooled by means of ice packs, which must be located within the container. Since these ice packs occupy a multiple of the volume of an evaporator according to the invention, on the one hand the internal volume is significantly reduced, or on the other hand, a larger insulating container necessary. Larger containers in turn have more outer surfaces over which more heat flows into the interior, which in turn must be buffered by larger ice packs.

The application areas are not limited to insulated containers. In principle, each article can be equipped with cooling elements according to the invention. It is advantageous, for example, the cooling of tents, in which even entire tent walls can be replaced by cooling elements according to the invention. The cooling of patients or injured in a hot environment or to reduce body temperature is just as possible as a use as a cooling vest, cooling suit or respirator.
In principle, the place of use will be found everywhere where today cooling batteries or ice rechargeable batteries are used. The cooling elements according to the invention can be stored for any length of time relative to the cooling and ice accumulators and can be adapted to the task to be cooled, since the evaporator is designed to be flexible.

Sorbents can reach temperatures of over 100 ° C during the sorption process. For such high temperatures, the multilayer films commonly used in the packaging sector are not always suitable. In particular, the polyethylene layers used for the sealing soften even at 80 ° C and leave the sheath to leak under vacuum. A sealant layer made of polypropylene, however, can withstand significantly higher temperatures. Its melting point is above 150 ° C.

In combination with high temperatures, sharp edges, corners and tips of the sorbent granules in the films can cause impermissible leaks. This danger can be counteracted by at least one polyester or polyamide layer within the multi-layer film. Polyamide films are particularly tear and puncture resistant. The actual gas barrier is ensured by a layer of thin metal foil or a metallized layer. For this, thin aluminum foils with a layer thickness from 8 μm have proven suitable. Less dense are metallized plastic films. Nevertheless, with short storage periods, the use of these metallized films is possible, especially since they are cheaper to produce compared to the metal foils.
The individual layers of a multilayer film are bonded together by adhesive. Conventional adhesives contain solvents which are not completely removed from the adhesive layer during bonding. Over long periods of time, these solvents then diffuse through the internal layers, affecting the vacuum within the cooling element. The diffusion is enhanced at higher temperatures, such as occur in the sorption and manufacturing process of the cooling elements. The adhesive used must therefore also be designed for high temperatures.
Advantageously, multi-layer films having a polyamide layer thickness of 12 to 50 microns, an aluminum layer thickness of 6 to 12 microns and a polypropylene layer thickness of 50 to 100 microns are used. Use find such films z. As for the packaging of foods that are sterilized after packaging for preserving at temperatures above 120 ° C.

Inventive multilayer films are z. B. on the company Wipf AG in Volketswil, Switzerland or the company PAWAG Verpackungen G.m.b.H., Wolfurt, Austria. When using such films cooling elements with a leakage rate of less than 1x10 high -8 mbarl / sec are possible. The shelf life thus reaches several years, without the cooling readiness is impaired.

The welding (sealing) of multilayer films to bags and the filling of bulk material and the subsequent evacuation are state of the art in the food industry.
Countless bag sizes and shapes are in use there. Particularly noteworthy are stand-up pouches, pouches with pouring openings, pouches with cardboard reinforcement, tear-open pouches, peel-effect pouches for easier opening and pouches with valves. All of them can be advantageous with their specific properties for the cooling elements according to the invention.

When filling solid sorbent in bags, dust forms, which deposits on the inner surfaces of the film. Dust on the subsequent sealing sites can lead to leaks if the dust layer is too thick compared to the polypropylene layer. Polypropylene layer thicknesses of 50 to 100 microns are sufficient to fine Dust granules melt into the polypropylene layer safely and vacuum-tight.

When using films according to the invention, it is possible to wrap hot, sharp-edged and dust-releasing sorbent directly under vacuum without further protective liners and to store it over a period of several years without foreign gases entering the cooling element from the film material itself or through it Impair sorption or even completely stop.

The sorbent used is advantageously zeolite. In its regular crystal structure, this can reversibly absorb up to 36% by mass of water. In the application according to the invention, the technically feasible water absorption is about 20 to 25%. Zeolites still have a considerable water vapor sorption capacity even at relatively high temperatures (above 100 ° C.) and are therefore particularly suitable for the use according to the invention.
Zeolite is a crystalline mineral that contains silicon and aluminum oxides in a framework structure. The very regular framework structure contains cavities,
in which water molecules can be sorbed with heat release. Within the framework structure, the water molecules are exposed to strong field forces whose strength depends on the amount of water already contained in the framework structure and the temperature of the zeolite.
Naturally occurring natural zeolite types absorb significantly less water. Per 100 g of natural zeolite, only 7 to 11 g of water are sorbed. This reduced water absorption capacity is due on the one hand to their specific crystal structures and on the other hand to non-active impurities of the natural product. For cooling elements, which also have the opportunity during a longer cooling period to release the heat of sorption via the shell, synthetic zeolites with their greater sorption capacity are therefore to be preferred. For cooling elements with high cooling capacity and / or short cooling time, in which the sorbent remains relatively hot, according to the invention also natural zeolites are used. At high sorbent temperatures, synthetic zeolites are no longer at an advantage over the natural ones. Typically, with inhibited release of the heat of sorption and concomitant high sorbent temperatures of over 100 ° C, both types can sorb only 4 to 5 g of water vapor per 100 g of dry sorbent mass. Economically, even the natural representatives are clearly in the advantage for this application, since the price is considerably lower.
Natural zeolites have another advantage. The non-active admixtures are typically 10 to 30%. Although they are not actively involved in the production of refrigeration, they are still heated by the neighboring zeolite crystals. They thus act as an additionally installed, inexpensive heat buffer. The result is that the zeolite filling is less hot and thus sorb additional water vapor at lower temperatures can.

Natural zeolite granules consist of broken or crushed fragments and therefore have sharp and pointed geometric shapes that can pierce or cut through the multi-layer films under vacuum and elevated temperatures.

Among the approximately 30 different natural zeolites, the following are to be used advantageously for the cooling elements according to the invention: clinoptilolites, chabazites, mordenites and phillipsites.
Naturally occurring substances can also be returned to nature without environmental requirements. Natural zeolites can after their use in cooling elements z. B. be used as soil conditioner, as a liquid binder or to improve the quality of water in stagnant water.
Of the synthetic zeolite types, the types A, X and Y, each in their inexpensive Na form are recommended.

In addition to the combination of zeolite / water, other solid sorption pairings are also possible for use in cooling elements according to the invention. Particularly noteworthy are bentonites and salts, which also represent suitable combinations with the working medium water. Activated carbon can also be an advantageous solution in combination with alcohols. Since these pairings also work under reduced pressure, they can be welded in multi-layer fabrics according to the invention.

According to the invention, the amount of sorbent is to be dimensioned and arranged so that only a minimal pressure drop within the sorbent must be overcome for the incoming water vapor. The pressure drop should be less than 5 mbar, in particular for water as working fluid. In addition, the sorbent must provide the inflowing agent vapor sufficient surface for attachment. In order to ensure a uniform sorption within the sorbent and a low pressure drop, particularly sorbent granules have been proven. Granule diameters between 2 and 10 mm show the best results. These are easy to unpack and form after evacuation a hard, pressure and dimensionally stable sorbent-shaped body, which retains the forced upon evacuation form. In order to still be able to represent variable geometries with the dimensionally stable sorbent moldings, according to the invention the sorbent is introduced into a plurality of regions connected only via steam flow channels. The individual solid areas can then, if the steam channel is still flexible, move against each other, fold and stack to z. For example, cramped spaces to satisfy and still allow a good air flow around.

Also advantageous are zeolite powder preformed, dimensionally stable zeolite blocks, in which already the flow channels can be incorporated and whose shape is adapted to the desired cooling element geometry. The stable zeolite blocks may have cavities in the region of the working medium vapor channel in order not to obstruct the flow.

The sorption heat releases heat of sorption that heats the sorbent. The absorption capacity for water decreases sharply at higher sorbent temperatures. In order to maintain a high cooling capacity over a longer period, it makes sense to cool the sorbent.
In direct contact of the sorbent with the multi-layer film resulting heat of sorption can be dissipated unhindered through the film to the outside. As a rule, the heat will be dissipated to the surrounding air. It is also very efficient to cool the sorption container with water.

Since the heat transfer to an air flow from the outside of the sorbent bag is of the same order of magnitude as the heat transfer of a sorbent granulate to the inside of the bag, in principle large film surfaces without ribbing, such as cylinder, plate or tube geometries, are recommended. In particular, since zeolite granules have a low heat conduction, the sorption containers are to be designed so that the average heat conduction within the sorbent does not exceed 5 cm.

All applications are characterized in that a cooling element is stored for an indefinite period at any ambient temperatures. At the start of the cooling effect, the control element is opened. From this point on, working agent vapor can flow to the sorbent and be deposited by it. The sorbent becomes hot because it liquefies and adsorbs the vapor within its crystal structure. The evaporator cools down and can be used as a source of cold. In the case of rapid cooling tasks (eg cooling of a liquid), the period of time will generally be insufficient to cool the sorbent appreciably. The working fluid vapor capacity will therefore be limited because of the hot sorbent temperatures unless admixtures act as heat buffers.
For cooling elements with a longer cooling time, the sorbent will be able to give off heat through the multi-layer film and, depending on the application, this heat can also be transferred to a product to be kept warm at a higher temperature level.

For applications in the deep-freeze area are also sufficiently sized flow channels and optionally freezing point-lowering additives in Work equipment to be considered. With these additives, water evaporation temperatures below zero ° C can be achieved even with the working fluid without the water freezing.

In particular, in applications in temperature-controlled transport, it may happen that the ambient temperatures are below the control temperature of the thermostat. When the temperature drops, the thermostat will first close and interrupt the active cooling of the cooling element. As soon as the temperature in the evaporator drops below 0 ° C, when pure water is used, it solidifies and releases the solidification heat at 0 ° C into the interior. If the water filling is sufficiently dimensioned, then the interior temperature will not fall below the freezing point.
For transport tasks where 0 ° C is too low, instead of pure water, an aqueous eutectic mixture may be used whose transformation point is set slightly below the control temperature of the thermostat (eg transformation point 3 to 4 ° C and a thermostat control temperature of 5 ° C). In this constellation is thus, as long as the temperature of the interior is above the control temperature of the thermostat evaporate working medium vapor from the aqueous mixture and cool the interior. At temperatures below the control point, the thermostat closes the steam channel. If the outside temperature falls below the transformation point and heat from the mixture continues to flow to the environment, the temperature in the evaporator will drop until the mixture falls below the transformation point. The mixture now transforms and gives off heat to the interior. Accordingly, with appropriate dimensioning, a cooling element according to the invention can not only cool at a constant temperature but provide heat of transformation when it falls below this temperature and keep the transported goods at least at the transformation temperature.

For applications in which no enlargement of the evaporator volume is desired by additional eutectic mixtures, according to the invention, a separate heat source can also be arranged between the evaporator and the container insulation. In the simplest case, this heat source does not need its own regulation, since its excess heat is dissipated by the evaporator through its thermostatic control before the higher temperatures reach the cargo. The output of this heat source should be such that their heat dissipation is sufficient to keep the insulated container at the lowest expected ambient temperatures at least to the required indoor temperature. According to the invention, the heat source also does not have to be arranged homogeneously within the insulated container. Rather, it is sufficient a selective heat release, since the evaporator acts as a steam heater, which distributes the amount of heat absorbed by the heat source over the entire evaporator surface and controls. Water in the thermal contact with the heat source evaporates, condenses within the evaporator structure on cooler surfaces and heats them to the level of the evaporating site. The temperature of the entire evaporator thus remains homogeneous. As soon as the temperature at the thermostat exceeds its control temperature, the control element opens and allows working medium vapor to flow into the sorbent until the control temperature has been reached again.

Of course, this is excellent electrical heating elements that are powered by entrained batteries or rechargeable batteries. In this type of heat source, the heating element can also be controlled via an additional, electrical thermostat.

As a separate heat source, in principle all known exothermic chemical reactions are suitable, which are used for keeping bodies warm (eg open flames, catalytic combustion, etc.). Particularly advantageous is the oxidation of iron powder with atmospheric oxygen in the presence of water, salts and activated carbon. This slow-running oxidation consumes only a small amount of oxygen, which is either diffused into the interior through the generally porous insulation walls or else directed from the outside to the heat source via suitably dimensioned openings.

According to the invention, the power of these heat sources can be regulated via the air supply (oxygen supply). In times when no heat is required, the air supply can be completely suppressed but be further increased below a limit temperature. By controlling the air supply, both the cooling capacity of the cooling element and the heat capacity of the heat source can be reduced.
Without regulation, a once activated heat source would still heat even if the ambient temperature is already well above the desired interior temperature. In these cases, the cooling element would have to dissipate both the heat incident from the outside and the heat of reaction released by the heat source. Since the ambient temperatures can fall or rise several times above and below the required interior temperature during a transport lasting several days, regulation of the heat source makes sense.

According to the invention, the air supply to the oxidation process of the heat source can be regulated by means of its own air thermostat which, depending on the ambient temperature, more or less releases the air supply to the heat source. The heat source is advantageously located within the insulating container, distributed on one or more surfaces between the inner Isolierboxwand and evaporator. The air thermostat may include a bimetallic element that closes the outer end of an air duct above a threshold temperature. In order to let oxygen-poor air flow out of the interior, the airtight bag may be provided with another opening over which is consumed Air can flow into the interior of the insulated container. From there, the air can get over the natural pores of the insulating material to the outside or it will be appropriate outlet openings created that allow the exchange of air and are selectively opened when starting the heating element. Through the targeted opening of the openings can also be prevented that the heat source is automatically activated during storage time unintentionally at low storage temperatures.
Ideally, the inlet opening and the outlet opening are at different heights. In this case, a natural air movement is used and with open air thermostat, supported by thermal buoyancy of the heated air at the heat source, always new oxygen to the stored iron powder to transport.
Ideally, the supply of fresh air through the air thermostat will begin when the ambient temperature falls below the average of the set control temperature. The lower the outside temperature drops, the further the air thermostat should open to increase the power of the heating source. An exact power control is not necessary because the exact temperature control takes over the thermostatic valve in the cooling element. Too high an output of the heat source is dissipated by the cooling element before the useful volume would be affected. The heat source is therefore preferably arranged between Isolierbehälterwand and evaporator surface.

Only in rare cases, the working fluid in the evaporator can be present in unbound form. Mostly it is distributed in an absorbent fleece and fixed by hygroscopic forces. Particularly low-priced materials are absorbent papers, as they are used in a great variety for household and industry for the absorption of liquids. The water-storing nonwovens, as well as the spacers made of plastic or natural zeolite, must not outgas under vacuum and higher temperatures. Commercially available microfibers made of polypropylene are particularly suitable for this purpose. These fibers are prepared for water absorption and do not emit the vacuum disturbing gases.
Advantageously, the evaporator in the region of the heat source is assigned a slightly larger amount of fleece, so there is also more liquid working fluid for steam heating available. In addition, the fleece geometry can be designed in this way; that a decreasing amount of working medium is refilled via the suction effect of the nonwoven material.
Another solution opens the fixation of the working fluid in organic binders such. B. Water Lock from Grain Processing Corp. USA. Also advantageous may be the combination of several measures mentioned above.

In order to maintain the necessary Dampflcanalquerschnitt between evaporator and Sorptionsmittelfiillung despite the pending from the outside air pressure, According to the invention, the steam channel can be formed and stabilized by several layers of a plastic net. There remains enough cross section for the flow between the network structure. When using polypropylene nets higher temperatures can be allowed without gas release. The flexible structure of the nets also optimally adapts to the respective geometries.

According to the invention, the evaporator can take on any shape and be made of different materials. Technically, it is necessary that during the cooling process a sufficiently large opening for the outflow of water vapor in the working medium vapor channel remains working fluid remains in the liquid state at the point to be cooled, entrainment of liquid components is prevented and a good thermal connection to the object to be cooled possible is.

The sealing of the multi-layer films usually takes place thermally by pressing hot sealing bars onto the outer film surfaces until the superimposed sealing layers become liquid and fuse together.

The welding process can take place within a vacuum chamber under vacuum. In this case, in the vacuum chamber at the same time from the water mass and all other components sucked out all the later adsorption process obstructing gases.

It is also advantageous, however, to evacuate the bag without a vacuum chamber at a still open point of the sealed seam by means of a suction device. In order to keep the suction channel open, a polypropylene spacer, advantageously in analogy to the structural material that spans the flow channel in the interior of the cooling element, is inserted between the foil surfaces. Once the evacuation is complete, the foil surfaces, including the spacer, are heated by sealing bars until the sealing layer and the identical material of the spacer merge into one another and enter into a gastight connection upon cooling.

• Fig. 1 ein erfindungsgemäßes, noch flach liegendes Kühlelement für die Kühlung einer isolierten Transportbox,
• Fig. 1a ein nahezu baugleiches Kühlelement mit einem separaten Zeolith-Beutel,
• Fig. 2 den flexiblen Verdampfer aus Fig. 1 in perspektivischer und geschnittener Darstellung,
• Fig. 3 das Kühlelement nach Fig. 1 zusammen mit einer isolierten Transportbox,
• Fig. 3a eine Wärmequelle,
• Fig. 3b eine Wärmequelle innerhalb einer isolierten Box,
• Fig. 4 ein Thermostatventil,
• Fig. 5 ein Regelorgan für einen Einwegkühler,
• Fig. 6 eine weitere Ausgestaltung eines Verdampfers in geschnittener Darstellung und
• Fig. 7 einen Sorptionsmittel-Bereich mit drei Sorptionsmittel-Taschen.

The drawing shows in:

• Fig. 1 an inventive, still lying flat cooling element for cooling an insulated transport box,
• Fig. 1a a nearly identical cooling element with a separate zeolite bag,
• Fig. 2 the flexible evaporator Fig. 1 in perspective and in section,
• Fig. 3 the cooling element after Fig. 1 together with an insulated transport box,
• Fig. 3a a heat source,
• Fig. 3b a heat source inside an insulated box,
• Fig. 4 a thermostatic valve,
• Fig. 5 a regulating device for a disposable cooler,
• Fig. 6 a further embodiment of an evaporator in a sectional view and
• Fig. 7 a sorbent section with three sorbent pockets.

This in Fig. 1 (and Fig. 1a ) shown cooling element still has its flat shape, as dictated by the manufacturing process. Two suitably cut multi-layer films 7 are stacked with their opposite sealing layers and equipped with the individual components of the cooling element. In the drawing, the upper multilayer film 7 is shown transparent to show the position of the components. The two multilayer films 7 consist of four individual layers bonded together. The films are hermetically sealed (welded) at the peripheral edges 23 via the innermost polypropylene layer. A gas-tight aluminum layer is enveloped in each case by two polyamide layers, which in turn protect the aluminum layer against destruction and allow a graphic printing of the multi-layer film. The evaporator 2 contains two superimposed integral spacers 11 on which six fleece plates 10 are placed. The fleece 10 consists of several layers of a hydrophilic microfiber mat of polypropylene. It is soaked with the working fluid water. The maximum water absorption is limited because of the externally applied pressure on the capillary structure of the microfiber. The filled amount of water is slightly larger than can be absorbed by the amount of sorbent. At low ambient temperatures, the surplus water mass can freeze and keep the interior of the insulation box at 0 ° C during icing. The six nonwoven sheets 10 are spaced at predetermined crease lines 24. Under a nonwoven a thermostatic valve 8 is inserted, from which a working medium vapor channel 4 leads to a control element 3 and from there into the sorbent 1. The working medium steam channel 4 is clamped by a flexible tubing 24 made of plastic, which withstands the external overpressure and is not crushed even when kinking. Under vacuum, the multi-layer film 7 nestles around the internals, that the way to the sorbent 1 for the water vapor only by the thermostatic valve 8, the tubing 24 and the control element 3 is possible.

For the manufacture of the cooling element according to the invention, the cut multi-layer films 7 are pre-sealed segment-wise, equipped with the individual components and then welded to a small suction opening 40 in the region of a sealed seam 23. To the suction opening 40, a vacuum pump is docked, the air from the cooling element and possibly released Suction gases. Following this, the suction opening 40 through which, in order to keep open the suction channel, a part of a spacer 11 protrudes, heated by means of suitable welding bar so far that the material of the spacer 11 merges with the sealing layer. Under certain geometric conditions, it may be advantageous if the evaporator 2 and the sorbent 1 are evacuated at separate locations.

Fig. 1a shows against the disposable cooler Fig. 1 following variations:
The flexible tubing 24 now leads from another point from the evaporator section 2 in the sorbent 1. The sorbent 1, in this case zeolite, has been filled within a separate bag 47 and additionally enclosed by the multilayer films 7. To make the vapor connection of the bag 47 must be pierced by the control element 3. For this purpose, the control element 3 has sharp edges which pierce the envelope of the bag 47 by a strong, external impact on the covering multilayer film 7. The flexible tubing 24 between the evaporator 2 and control element 3 is in this embodiment of a plastic corrugated hose, which holds thanks to its structure even with thin material thickness the external air pressure and still allows an extremely flexible working medium vapor connection. The six nonwoven sheets 10 are contacted at the crease lines 24 by further nonwoven material 57 in order to redistribute the liquid working medium evenly by the suction effect of the material if it should evaporate through a partially acting heat source at the contact points and recondensate in other places.

Also the production of the disposable cooler after Fig. 1a differs from the production method of the disposable cooler Fig. 1 , The preparation of the bag 47 can be done separately. It does not have to be evacuated and sealed simultaneously with the sealing of the cooling element. Rather, it can be filled, evacuated and sealed in a separate manufacturing step with hot zeolite. In the final production of the cooling element of the cooled bag 47 is inserted together with the other components between the multi-layer films 7 and aligned with the control member 3 and the flexible hose 34. The evacuation takes place in this example within a vacuum chamber in which all components are removed, including the working fluid water of adhering or contained, gassing residues. Even within the vacuum chamber, the cooling element is welded to the still open sealing seams and removed as a finished unit from the re-flooded vacuum chamber.

Fig. 2 shows the evaporator 2 according to Fig. 1 cut along the line AA and in perspective view. Along the fold lines 24, the evaporator 2 has been folded into its cubic shape. At the cut surfaces of the spacer 11 and the water-impregnated nonwovens 10 are visible. Everything together is wrapped by the multilayer film 7. In the area of the kinks 24 there is no fleece 10, so that the upper multi-layer film 7 can push through to the spacer 11 in order to compensate for the length contraction resulting from the outer film. In this way, a slight deformation of the evaporator 2 without wrinkling can be achieved. On the left wall of the evaporator 2, the thermostatic valve 8 is inserted between web 10 and spacer 11. About the spacer 11 are all areas of the nonwovens 10 with the thermostatic valve 8 in conjunction.

Fig. 3 shows the cooling element according to Fig. 1 in the folded state before insertion into an insulated transport box 12 which can be covered with a cover 25. The transport box 12 has at one edge a free space 26, in which the Arbeitsmitteldarripfkanal 4 can be used. The control element 3 and the sorbent 1 thus come to lie in the outer region of the transport box 12 on a side wall. The six surfaces of the evaporator 2 that are folded into a cuboid occupy the six inner surfaces of the transport box 12. The resulting interior space serves to receive a transport item. The upper evaporator plate 5 is hinged. About them the interior is accessible in full cross section. On two inner walls of the transport box 12 are recesses 27, each of which can receive a heat source 18. The heat sources 18 contain a mixture of iron powder, water, salt, cellulose and activated carbon in an air-permeable casing. When exposed to air, the iron powder oxidizes exothermically. The atmospheric oxygen passes through the porous styrofoam insulation of the transport box 12 to the iron powder and / or additional, thin air channels 28 in the recesses 27. The heat sources 18 provide heating of the interior in the event that the transport box 12 in a respect to the control temperature of the thermostat 8 is too cold environment. The heat development of the heat sources 18 itself remains unregulated. If the heat sources 18 supply more heat than is needed for the interior, the thermostatic valve 8 opens and allows so much steam to flow into the sorbent 1 until the evaporator temperature is within the control range again. Since the evaporator 2 contains only water and water vapor, the temperature throughout the evaporator 2 remains homogeneous. Of evaporator lots in the, z. B. of the heat sources 18, more heat is incident, water evaporates under heat absorption and in areas from which heat flows to the environment, steam will flow and condense exothermic. Due to the capillary suction effect of the nonwoven material, the water concentration can equalize again.

Fig. 3a FIG. 5 shows a heat source 48 in a marginally sealed, gas tight foil wrap 49 containing an entrance port 50 and an exit port 51. The heat source 48 contains two paper bag-filled reactive iron powder blends 58 that undergo an exothermic reaction when exposed to oxygen. In order to ensure the air access are within the film sleeve 49th other flow paths kept open. In the exemplary embodiment, the flow paths are spanned by a flexible grid 52. The inlet opening 50 is connected in a gas-tight manner to a hose line 53, which can be closed at its outer end by an air thermostat 54. The outlet opening 51 is closed with an adhesive tape 51. It is only deducted to start the heat source 48. The air thermostat 54 may also be closed until its use with an additional sheath (not shown). The heat source is dimensioned so that it can be bent in the middle and thus cover two inner surfaces of an insulated box.

Fig. 3b shows the heat source 48 from Fig. 3a inserted in an insulated box 60 in a sectional view. The air thermostat 54 is disposed at a lower corner outside the box 60. It contains a bi-metal spiral, which opens the inlet opening 50 below a temperature of 5 ° C. The tubing 53 forms the gas-tight connection from the external air thermostat 54 through the insulation of the box 60 to the inlet opening 50. The heat source 48 is centrally kinked and covers the bottom and a side wall of the box 60. The flexible grid 52 and the two iron powder mixtures 58 are surrounded by the gas-tight film envelope 49. At the upper end of the heat source 48 is the outlet opening 51. It is still closed with the adhesive tape 55. To start the heat source 48, the adhesive tape 55 must be removed. By the air inlet starts the exothermic reaction and heats the air in the grid, which then rises heated, flows through the outlet opening 51 into the box and flows from there via a small ventilation duct 59 in the lid 61 of the box 60 to the outside and at the same time opened air thermostat 54 new oxygen-rich air via the hose 53 can flow. On the presentation of a box 60 lining and applied to the heat source 48 cooling element has been omitted.

Fig. 4 shows a thermostatic valve 8 in cross section. A rolled into a spiral bi-metal strip 9 is fixedly connected at its inner end 41 with a housing 29 open on one side, while the free end 42 includes a sealing disc 30 which closes the opening 31 of the working medium vapor channel 4 at the control temperature. The opening 31 is formed by a gas-tightly integrated into the housing 29 pipe section 38, on the other end of a plastic hose 14 is pushed. Around the tube 14 in turn nestles the multi-layer film 7, which is sealed gas-tight at the edges 23. The multi-layer film 7 and the tube 14 can be pressed so far in the further course by engaging from outside squeezing (not shown) that the working medium vapor channel 4 can be blocked from the outside. To start the cooling, the squeezing elements are removed. By the restoring forces of the plastic hose 14 now opens the flow path for the working medium steam. The control element according to the invention is formed in this embodiment by the thermostatic valve 8 and the squeezing. Under the housing 29 of the thermostatic valve 8 is a layer of a plastic network 43. Since the threads 39 of the network 43 overlap at the intersections, remain Arbeitsmitteldampflkanäle also within the network level. Good results are obtained with nets that have a thread thickness of about 2 mm with a thread spacing of about 3 mm. Although the microfiber of the nonwoven fabric is pressed onto the plastic net 43 from one side of the mesh and the flexible multilayer film from the other side, sufficient cross section remains for the working medium vapor. If the cross-section of individual areas is too short, z. B. in the inflow to the thermostatic valve 8, several layers of the plastic mesh 43 can be stacked. The flexibility of the evaporator 2 according to the invention thus remains intact.

Fig. 5 shows a control element 3 in a sectional view, which is kept closed by the fact that the external air pressure deforms the multilayer film 7 so far that a disk-shaped sealing surface 16 is pressed onto a sealing seat 17. The sealing seat 17 is again formed by a piece of pipe 32 on the second end of a flexible plastic corrugated hose 13 is attached. On the rectangular continuation 44 of the working medium vapor channel 4, a corrugated hose 13 is also pushed from plastic. The continuation 44 begins in a plastic housing 33 in which the sealing surface 16 can be lifted or unfolded from the sealing seat 17 without hindrance by the multi-layer film 7. The lever force required for folding is applied via a lever rod 34 connected to the sealing surface 16. The lever rod 34 is embedded in a suitably cut side pocket 45 of the multilayer film 7. These side pocket 45 is sealed vacuum-tight at the edges 23. Under vacuum, the sealing surface 16 is pressed by means of the multi-layer film 7 and lever rod 34 to the sealing seat 17. A slight tilting movement on the lever rod 34 from the plane of the drawing deforms the multilayer film 7 so far that the path for the working medium vapor can be released completely or in metered form. With an optimal structure of the control element 3, the sealing surface 16 closes automatically as soon as the tilting force on the lever rod 34 falls away.

Fig. 6 shows a further embodiment of a cut and perspective illustrated evaporator 2, which absorbs heat from an air stream to be cooled. The flow channel 37 for the air flow is formed by the evaporator 2 itself and clamped. For this purpose, the originally flat produced evaporator 2 was folded around a centrally applied Arbeitsmitteldampflcanal, which is formed in this embodiment of a perforated corrugated tube 13, after evacuation by 180 °. The originally opposite seal seams 35 and 36 are now directly opposite. Because the inner Film ends are cut shorter than the outer, the outer ends 22 of the multilayer film 7 can be re-welded and thus hermetically closed. Form flow channel 37 for the air flow. At the rear end 46 of the flow channel 37 of the flat air flow is converted into a round flow geometry.
In the embodiment shown, the working medium vapor channel is formed by two layers of a net-shaped spacer 11. The webs 10 are in thermal contact with the flow channel 37.

Fig. 7 finally shows a sketch of the filled with sorbent area of a cooling element. The multi-layer film 7 is divided into three pockets 19, which communicate with each other only through the working medium vapor channel 4. The working medium steam channel 4 can be formed by a perforated corrugated hose (not shown), which is extremely pressure-stable and at the same time flexible due to its corrugation. The three sorbent bags 19 contain a Zeolithschüttung which is pressure-stable under vacuum but inflexible. In the overflow areas 39, where no zeolite is filled, the structure remains flexible thanks to the flexible corrugated hose. At these overflow areas 39, the entire cooling element can be folded in order to optimally adapt to the task required in each case.

Claims (24)

Cooling element with a sorption agent (1) which can sorb a vaporous working medium under vacuum, which evaporates from a liquid working medium in an evaporator (2) and with a control element (3) in a working medium vapor channel (4) between sorbent (1) and evaporator ( 2)
characterized in that
the entire cooling element is hermetically enclosed by a gas-tight multilayer film (7),
the multilayer film (7) is designed to be flexible and under vacuum so the control element (3), the working medium vapor channel (4) and the evaporator (2) surrounds that evaporator (2) and working medium vapor channel (4) remain flexible and the working medium vapor only over the control element (3) can flow to the sorbent. Cooling element according to claim 1,
characterized in that
the control member (3) includes a valve (6) operable by deforming the multilayer film (7). Cooling element according to one of the preceding claims,
characterized in that
the control element (3) contains a thermostatic valve (8). Cooling element according to one of the preceding claims,
characterized in that
the thermostatic valve (8) in the evaporator (2) is arranged. Cooling element according to one of the preceding claims,
characterized in that
the thermostatic valve (8) contains a control body made of bi-metal (9) and is in thermal contact with the liquid working fluid. Cooling element according to one of the preceding claims,
characterized in that
the sorbent (1) zeolite and the working fluid contains water. Cooling element according to one of the preceding claims,
characterized in that
the evaporator (2) contains a fleece (10) from which the working fluid can evaporate and a spacer (11) which forms between the fleece (10) and multi-layer film (7) working medium steam channels (4). Cooling element according to one of the preceding claims,
characterized in that
the flexible evaporator (2) covers a plurality of inner walls of a thermally insulated container (12). Cooling element according to claim 8,
characterized in that
at least one surface of the evaporator (2) is designed to be foldable. Cooling element according to one of the preceding claims,
characterized in that
the liquid working fluid contains substances which shift the solidification point to +2 to +4 ° C. Cooling element according to one of the preceding claims,
characterized in that
the working medium vapor channel (4) contains a flexible corrugated hose (13). Cooling element according to one of the preceding claims,
characterized in that
the working medium vapor channel (4) contains a piece of tubing (14) which can be squeezed by external squeezing elements to inhibit the flow of the working medium vapor. Cooling element according to one of the preceding claims,
characterized in that
the control member (3) includes a sealing surface (16) which is pressed by the multi-layer film (7) onto a sealing seat (17). Cooling element according to claim 8,
characterized in that
a thermally insulated container (12, 60) via a heat source (18, 48) which heats its interior at lower ambient temperatures. Cooling element according to claim 14,
characterized in that
the heat source (18, 48) contains iron powder which maintains an exothermic reaction upon the admission of atmospheric oxygen. Cooling element according to one of the preceding claims,
characterized in that
the heat source (48) is surrounded by a gas-tight film envelope (49) and the access of atmospheric oxygen is controlled via an air thermostat (54). Cooling element according to one of the preceding claims,
characterized in that
the air thermostat (54) is open at ambient temperatures below the required working chamber temperature and allows fresh air to flow to the iron powder and does not allow fresh air to flow in at ambient temperatures above the useful room temperature. Cooling element according to one of the preceding claims,
characterized in that
the gas-tight film envelope (49) next to an inlet opening (50) also has an outlet opening (51) for low-oxygen air. Cooling element according to one of the preceding claims,
characterized in that
the outlet opening (51) is closed during storage and is opened to start the heat source (48). Cooling element according to one of the preceding claims,
characterized in that
the insulated box 60 contains a ventilation duct 59 for the discharge of oxygen-poor air. Cooling element according to one of the preceding claims,
characterized in that
the sorbent (1) is arranged in several parts (19) within the multi-layer film (7) and the parts (19) remain movable relative to each other and can be reached via flexible working fluid flow channels (4) from the working medium vapor. Cooling element according to one of the preceding claims,
characterized in that
the working medium vapor channel (4) is formed from flexible plastic nets (20) which maintain a sufficient cross section for the working medium vapor flow. Cooling element according to one of the preceding claims,
characterized in that
on the multilayer film (7) in the outer region of the evaporator (2) an air channel (21) is provided, via which in the evaporator (2) heat can be absorbed. Method for evacuating a cooling element according to one of the preceding claims,
characterized in that
the multi-layer film (7) in the region of a sealed seam contains a spacer (11) made of polypropylene via which a vacuum pump evacuates the interior of the cooling element and that after evacuation the spacer (11) is heated to such an extent that it is in contact with the sealing layer of the multilayer Foil (7) melts and forms a gas-tight, evacuated cooling element.

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