Patent Application
20180231279
The invention relates to an adsorber for a motor vehicle, to a method for producing such an adsorber, and to a vehicle having such an adsorber.
An adsorber is basically used in what is referred to as an adsorption system which serves predominantly for storing and later outputting heat. For this purpose, the adsorber has a housing in which a sorbent, i.e., a sorption material and a sorbate are arranged, wherein, depending on whether heat is to be discharged from or fed into the adsorber, said sorbate is incorporated into the sorbent or released therefrom. The sorbent is frequently a crystalline solid, and the sorbate is gaseous in the released state, and is then adsorbed by the sorbent accompanied by the outputting of heat. Known materials in this context are, for example, zeolite as sorbent and water as a sorbate. During the adsorption, adsorption heat, which is output by the adsorber, is then released. The incorporation typically takes place here in a purely physical way and is, in particular, of an electrostatic nature; there is no chemical bond present. In contrast, in the reverse process, specifically the desorption, heat is absorbed by the adsorber, in order to release the sorbate again, i.e., to desorb the sorbent.
The discharging of heat and feeding in of heat are typically carried out by way of a heat exchanger which is in contact with the sorbent. A heat medium flows through the heat exchanger itself and serves to transport heat to the adsorber and away from it. The adsorber is accordingly a heat accumulator which can be used both as a heat sink and as a heat source for cooling or heating other components which are thermally coupled to the adsorber via the heat exchanger.
In a vehicle, i.e., a motor vehicle, electric vehicle or hybrid vehicle, an adsorber is sometimes used as part of an adsorption system which serves to air-condition various parts of the vehicle, for example the passenger compartment. In this context, for example a zeolite-water system is used in which adsorption heat is released at the zeolite by way of the adsorption of water. For this purpose, the water is frequently arranged in a vessel or else reservoir which is connected to the zeolite in a pressure-conducting fashion. The water then vaporizes in the vessel accompanied by the absorption of heat. The use of such an adsorption system makes it then possible to dispense with a conventional refrigeration circuit and, in particular, with a compressor as well as conventional refrigerants.
The invention is based on the object of specifying an improved adsorber. Said adsorber is to be as efficient as possible, i.e., to have the highest possible power density and to ensure the most efficient possible heat transfer between the heat medium and the sorbent. In this context, special automotive requirements, which arise owing to the use of the adsorber in a motor vehicle, are also to be taken into account. These include, for example, the installation space, fabrication costs and mechanical stability of the adsorber, in particular in the case of impact loads and vibration loads. Furthermore, a method is to be specified for producing the adsorber, as well as a vehicle having such an adsorber.
The object and other objects are achieved by way of an adsorber in accordance with embodiments of the invention. Furthermore, one or more objects are achieved by way of a method in accordance with embodiments of the invention, and by way of a vehicle in accordance with embodiments of the invention. Advantageous refinements, developments and variants are also provided in other embodiments of the invention. In this context, the descriptions relating to the adsorber also apply correspondingly to the method and to the vehicle, and vice versa.
The advantageous refinements of the adsorber also give rise to an improvement in an adsorption system in which such an adsorber is installed. An object is therefore also achieved, in particular, by way of an adsorption system which has a number of such adsorbers as system parts.
The adsorber is designed for use in a vehicle, i.e., satisfies, in particular, the standards and regulations regarding safety and stability which are current in the field of vehicles. The adsorber has a housing and a heat exchanger as essential components. The heat exchanger has a wall which encloses a cavity for conducting a heat medium, for example a water/glycol mixture or a heat transfer oil. The heat medium serves predominantly to discharge heat from the adsorber and to feed heat to the adsorber. Correspondingly, the heat exchanger can be connected via suitable connections to a line system which permits heat to be transferred between various components of the vehicle and the adsorber.
The heat exchanger is arranged inside the housing, i.e., the housing surrounds the heat exchanger and forms an adsorber space which is therefore bounded and defined by an inner wall of the housing and an outer wall, also referred to as an outer surface, of the heat exchanger. A sorbent, for storing heat which is output by the heat exchanger and for outputting stored heat to the heat exchanger is arranged in the adsorber space. The storage and the outputting of heat are carried out here, in particular, by way of desorption and adsorption of a sorbate. For the exchange of heat, the outer surface of the heat exchanger is in contact with the sorbent, i.e., the sorbent is arranged on the outer surface. In this context, in particular, at least 75% of the outer surface is in thermal contact with the sorbent, i.e., at least 75% of the outer surface is in planar or punctiform contact with the sorbent.
In particular, the adsorber is part of an adsorption system which has a reservoir for the sorbate. The reservoir is connected to the adsorber space, with the result that during the desorption, excess sorbate is intermediately stored in the reservoir accompanied by an outputting of heat there. During the adsorption, sorbate is correspondingly fed into the adsorber space from the reservoir accompanied by absorption of heat there. The adsorber space in the adsorber and the reservoir of the adsorption system are connected to one another in a first variant by way of a suitable line and form together a system which is closed off, in particular in a pressure-tight fashion, from the surroundings, with the result that no sorbate escapes. It is also contemplated that a plurality of adsorber spaces and/or a plurality of reservoirs are connected to one another to form such a closed-off system and then form a sorbate distribution system. In a second variant, the reservoir is arranged directly at one end of the adsorber space and forms a collector space there. In this context, the adsorber space and the reservoir also correspondingly form a system which is closed off in a pressure-tight fashion. Generally, the term pressure-tight system is understood to mean, in particular, that this system is vacuum-tight up to an absolute pressure of approximately 5 to 10 mbar. Furthermore, the cavity in the heat exchanger, in which a heat medium is conducted, and all the adsorber parts and system components and, in particular, lines which are used to conduct the heat medium, are expediently configured in an overpressure-tight fashion, in order to conduct the heat medium up to an overpressure of up to 80 bar.
Further requirements owing to the automotive use arise, for example, with respect to the environmental compatibility of the materials and chemicals used. The sorbent and the sorbate are preferably nontoxic, in order to avoid leakage of toxic substances in the event of damage. Furthermore, the sorbent and the sorbate are expediently noncombustible or at least flame-resistant, in order to keep the potential hazard as low as possible in the case of an accident. The sorbate is then preferably water or a water/anti-freezing agent mixture, in particular a water/glycol mixture, and the sorbent is a zeolite or a mixture of a plurality of zeolites. In particular, a bonding agent, preferably with a proportion by weight of at most approximately 20% is added to the zeolite.
An advantage which is achieved with the invention is, in particular, the fact that improved exchange of heat within the adsorber between the sorbent and the heat medium is implemented through the specific and improved contact of the sorbent with the heat exchanger. The adsorber exhibits as a result particularly high dynamics, i.e., a high power density, i.e., a particularly high rate with which the sorbate is input and output by the sorbent, during operation. Furthermore, improved absorption of heat makes it possible to utilize the storage capacity of the sorbent to an optimum degree, with the result that the adsorber also has a particularly high heat storage capacity, i.e., energy density. The adsorber therefore has an improved size to performance ratio compared to conventional adsorbers. This is advantageous, in particular, in the case of an automotive application, i.e., use in a vehicle. A further advantage of the invention is in this context, in particular, the improved resistance to vibration and generally the improved robustness of the adsorber with respect to, in particular long-lasting, mechanical effects.
Of particular significance for the method of functioning and the efficiency of the adsorber is the transfer of heat between the heat exchanger and the sorbent, i.e., the sorption material. The efficiency is mainly dependent here on the contact, i.e., in particular the contact area between the sorbent and the heat exchanger. However, the improvement in the contact through simple scaling of the heat exchanger and/or simple enlargement of its external wall, i.e., external area, is usually achieved at the cost of significantly increased expenditure and the requirement for a considerably larger amount of space. The invention is then based on the idea that these two factors are disadvantages which are typically accepted with use outside the automotive field, but which, in the context of use specifically in this field, take on an entirely different significance. In this respect, the previous concepts for the configuration of an adsorber are not tailored in an optimum way to use in a vehicle. In contrast, according to one or more embodiments of the invention, particularly good contact is produced, and in this context, in particular, increased expenditure on fabrication is accepted, in contrast with the known embodiments.
The heat exchanger is, in particular, embodied as a tubular heat exchanger, tube bundle heat exchanger, lamellar heat exchanger, plate heat exchanger or microchannel heat exchanger. The heat exchanger generally has a cavity with a specific cross-section which determines what quantity of heat medium can flow per unit of time through the heat exchanger. The cavity is surrounded by a wall with a specific wall thickness which decisively determines the pressure-tightness and stability of the heat exchanger. Heat is exchanged between the heat medium and the sorbent via this wall, wherein the quantity of heat which is transferred per unit of time is determined essentially by the contact of the sorbent with the outer surface, i.e., the coverage thereof with sorbent.
In this context, specifically heat exchangers in which the largest possible outer surface is obtained with at the same time the smallest possible wall thickness are particularly suitable, in respectively suitable refinements. Against the background of the basic limitation of installation space in the automotive field, heat exchangers with dimensions which are significantly smaller in comparison with conventional heat exchangers are therefore preferred. In one refinement as a tubular heat exchanger, the heat exchanger then has an internal diameter which is advantageously at most 10 mm, wherein a refinement with at most a 6 mm internal diameter is particularly advantageous. The internal diameter is, however, in particular at least 1 mm. In one refinement as a tube bundle heat exchanger, i.e., as a heat exchanger with a multiplicity of tubular heat exchangers, these tubular heat exchangers each have an internal diameter which is preferably in the range from 1 to 6 mm. Such small tubular diameters are not selected, in particular owing to the increased expenditure on fabrication, in conventional heat exchangers for adsorbers, but they offer significant advantages, since with the same cross section there is, on the one hand, a significantly increased outer surface and, on the other hand, owing to reduced pressure stresses in the wall the wall thickness is also significantly smaller, permitting a saving in material and in weight.
Basically, in order to make the outer surface larger, it is possible to equip it additionally with a number of fins, lamellas, heat-conducting plates or generally with projections, wherein the term “lamellas” is used below in a simplifying fashion for any such projections, without restricting the generality. These lamellas then extend from the heat exchanger into the adsorber space and increase the outer surface correspondingly, i.e., the lamellas each have a surface which is part of the outer surface. The heat exchanger preferably therefore has a number of lamellas, wherein in a particularly suitable refinement the heat exchanger and the lamellas are embodied in one piece or in one part, i.e., the lamellas are not installed as separate components on the wall. As a result, particularly good transfer of heat from the lamellas to the wall is ensured. However, a configuration with lamellas which are attached to the wall is alternatively also conceivable. These lamellas are then, for example, welded or bonded on and preferably connected in a materially joined fashion to the wall, in order to ensure an optimum transfer of heat.
In particular in a refinement as a lamellar heat exchanger, but also generally in the case of a heat exchanger with lamellas, in one preferred refinement the outer surface is enlarged by virtue of the fact that the heat exchanger is embodied with a significantly increased lamellar density. In a lamellar heat exchanger with a plurality of lamellas which are, in particular, parallel to one another, said lamellas are then preferably arranged at a distance of at most 1 mm from one another. In other types of heat exchanger, in particular in the case of a tubular heat exchanger, two lamellas which are respectively adjacent, which are also frequently referred to as fins in this context, are spaced apart from one another by preferably at most 2 mm.
In one suitable embodiment, the heat exchanger extends in a longitudinal direction, which during operation is also a direction of flow of the heat medium in the heat exchanger, and the lamellas are, in particular, embodied in an elongate fashion and extend straight in this longitudinal direction. However, in a second suitable variant, the lamellas have a relatively complex profile and extend, for example, obliquely or perpendicularly with respect to the longitudinal direction, and in a tubular heat exchanger they extend, in particular, in a helix-like fashion around said heat exchanger, with the result that a throughput of heat which is generally additionally generated by the lamellas is increased further. In principle, a profile in which the lamellas intersect or overlap one another is also contemplated here.
The refinement of the lamellas described above relates to the profile thereof along the wall of the heat exchanger, i.e., a longitudinal profile of the lamellas. Alternatively or additionally in one advantageous refinement the lamellas also start from the wall and follow, into the adsorber space, a relatively complex, i.e., non-linear, profile, in particular a curved profile. As a result, in comparison with lamellas which extend straight outward, a significantly larger additional area can be accommodated in the same construction volume. This embodiment is particularly suitable in the case of a tubular heat exchanger or lamellar heat exchanger in which the profile starting from the wall to the outside is then a radial profile. In one advantageous variant, a complex longitudinal profile is combined with a complex profile from the wall toward the outside.
In addition, a space which, in particular in the case of a tubular heat exchanger, preferably increases outward is formed between two respectively adjacent lamellas. As a result, improved flow of the, in particular, gaseous sorbate can be achieved in the region of the heat exchanger. Such spreading of the intermediate space between adjacent lamellas is, however, also implemented in the case of a lamellar heat exchanger, preferably by virtue of the fact that the lamellas each have a thickness which is reduced starting from the wall toward the outside, with the result that the lamellas are therefore made so as to be thinner toward the outside.
In one preferred development, at least two different types of lamellas are formed which are of different lengths starting from the wall toward the outside. As a result, so-called a lamella density gradient is generated, i.e., the number of lamellas which extend as far as a certain distance from the wall decreases as the distance from the wall increases. As a result, in particular the flow properties of the heat exchanger are then improved.
In one suitable refinement, the lamellas of different types are arranged alternately on the outer surface. In one preferred refinement, every second lamella is embodied so as to be merely half as long as the two lamellas adjacent thereto.
By way of a combination of the above-mentioned different types of lamellas with a complex profile of the lamellas, it is possible to obtain a refinement which is particularly suitable for automotive use and which is particularly compact and nevertheless has a particularly high power density. In this context, in particular the flow properties can also be adjusted particularly precisely.
The heat exchanger preferably has a carrier structure for the sorbent. The carrier structure significantly enlarges the outer surface, and the contact with the sorbate during operation is significantly improved. The carrier structure is, in particular, porous or fibrous, wherein the term “porous carrier structure” is understood in a first variant to mean a sponge-like structure, having a plurality of cavities which are in contact with one another and as a result form a network of open pores and/or channels. In this context, a respective cavity, i.e., a pore or a channel, has a diameter which is, in particular, smaller than 5 mm and larger than 0.02 mm.
In one particularly advantageous refinement, the carrier structure has a porosity and has a density which changes, in particular decreases, starting from the wall and toward the outside. In other words, the quantity of material is reduced toward the outside, and the density decreases toward the outside. In contrast, the porosity increases toward the outside, i.e., becomes larger toward the outside, and a number of cutouts in the material is increased. As a result, preferably a density gradient is formed which gives rise to a coarser porosity starting from the wall toward the outside, i.e., the diameter of the cavities increases as the distance from the wall increases. As a result, similarly to what has already been stated above in relation to the lamellas the carrier structure near to the wall is on average denser and therefore a high thermal conductivity is ensured and a high power density is implemented. In contrast, owing to the relatively large cavities more sorbent is arranged further outward, and/or an improved throughflow of sorbate is implemented further outward during operation, with the result that the arrangement also has a high heat storage capacity and power density.
For example, in a refinement with lamellas, these same lamellas are made so as to be porous, for example embodied as a porous or sponge-like structure, or a porous, in particular sponge-like structure, is applied to the wall proceeding toward the outside, for example in addition to lamellas or alternatively also in the case of a heat exchanger without lamellas. In this context, the carrier structure is then attached to the wall in a suitable way, for example securely bonded, securely soldered or securely welded.
However, in a first refinement, the carrier structure is embodied in one part, i.e., in one piece with the heat exchanger, that is to say, is formed into the wall or embodied as a projection of the wall toward the outside, as a result of which an enlarged surface is then advantageously combined with particularly high heat conduction.
In a second refinement, the carrier structure is embodied as a fiber bundle, having a plurality of fibers and having a plurality of intermediate spaces between the fibers, wherein the intermediate spaces then form the cavities of this, in this sense also porous, carrier structure. In this context, the term fibers is to be understood to mean, in particular, bodies which are thin, elongate elements such as e.g., wire sections, strips of sheet metal, threads or the like, and particularly also fibers or elements which have a particularly small diameter or a particularly small thickness, e.g., in the range from approximately 0.5 mm to approximately 0.02 mm. In one expedient refinement, the fibers are fabricated from aluminum and generally, in particular, from the same material as the wall of the heat exchanger, in order to ensure the best possible heat conduction. The sorbent is then arranged in the intermediate spaces, wherein the fiber bundle forms an advantageous enlargement of the outer surface. In one expedient refinement, the fibers are connected, at points, to one another in a mutually thermally conductive fashion, e.g., by sintering.
The fibers are then guided along the wall and/or around it and expediently pressed onto said wall or thermally conductively attached to the wall, e.g., by soldering or welding. The embodiment of the carrier structure as a fiber bundle is particularly suitable in combination with lamellas on the walls, wherein the fibers are then correspondingly laid between the lamellas, wherein the lamellas then form a number of intermediate spaces in which the fibers are laid and which are filled, in particular, by the fibers and the sorbent.
The heat exchanger is preferably fabricated from a lightweight metal, in particular from aluminum, which is particularly lightweight and cost-effective and additionally has good heat conduction properties. Aluminum is particularly suitable in particular for forming the abovementioned porous carrier structure. For example an aluminum sponge or aluminum foam is manufactured therefrom and is then attached to the wall. Steel is also suitable as a material, and so, in principle, is also copper which has particularly good heat conduction properties, but is less preferred owing to its electrochemical properties. In one advantageous alternative, metal is not used but instead a temperature-resistant plastic is used which is distinguished, in particular, by low costs, good heat conduction properties, a high level of flexibility, simple fabrication and low weight. The adsorber is generally embodied in a temperature-resistant fashion, which is to be understood as meaning, in particular, that the adsorber withstands a temperature of approximately 150° C. up to approximately 300° C., in particular a temperature of the heat medium of this order of magnitude.
Particularly a rapid prototyping method, in which the adsorber, i.e., here the housing and the heat exchanger thereof, are advantageously produced in one piece, is suitable for producing the heat exchanger or the entire adsorber. In one advantageous variant, parts of the adsorption system such as e.g., gas-tight or pressure-resistant line geometries for guiding sorbate or heat medium are also produced in one piece with the adsorber. In this context, e.g., both metal and plastic are contemplated as the starting material. During the production by way of a rapid prototyping method, the wall thickness of the heat exchanger is expediently at least 0.5 mm, in order to ensure sufficient gas-tightness. Depending on the specific selection of material, the wall thickness can, however, also be smaller. A refinement of the heat exchanger or of the entire adsorber as a rapid prototyping part entails, in particular, the advantage of particularly high ease of shaping, as a result of which the adsorber can be adapted in an optimum fashion to the respective installation space situation in the vehicle and as a result of which the amount of installation space required is further reduced.
However, an alternative refinement of the adsorber is particularly suitable such that only the housing or a part of it is produced as a rapid prototyping part, in particular in combination with parts of the adsorption system, but the heat exchanger is not, with the result that for the heat exchanger it is possible to have recourse to semi-finished products and cost-effective standard methods, while the housing and/or, if appropriate, the corresponding parts of the adsorption system is or are fabricated according to requirements and with adaptation to the automotive use. In this context, suitable connections, for distributing and/or feeding on the heat medium to the components of the vehicle to be cooled or to be heated and/or to other adsorbers which are accommodated in the vehicle, are expediently also formed directly on the housing.
Extruded profiles, which are produced, in particular, in an extrusion method and as endless products, are especially suitable as a particularly cost-effective semi-finished product for producing the heat exchanger, in particular a tubular heat exchanger or tube bundle heat exchanger. During the production of such extruded profiles, the lamellas are then advantageously also formed at the same time.
Alternatively, production of the heat exchanger, of the housing, or of the entire adsorber by way of a casting method or injection molding method is also advantageous. Such a method is preferably used to produce the porous carrier structure. For this purpose, in a first step, a casting mold is filled with a sacrificial material which generates the cavities in the material during the injection of the material, and is liquefied or vaporized owing to the temperature of the injected material, and then, or even later, e.g., in a separate lost wax process, flows away, with the result that a porous structure with cavities which are connected to one another remains. For example, a plurality of plastic balls is used as a sacrificial material, which balls each have a diameter which then corresponds approximately to the diameter of the respective cavity.
The entire heat exchanger is advantageously produced by way of the previously mentioned injection molding method, wherein the cavity is then kept free by a corresponding molded part made of the sacrificial material. It is to be noted here that in this context a closed wall is also formed for the cavity, e.g., also as a component of the housing. As a result, a single-piece heat exchanger with a porous carrier structure on its wall can be produced in a particularly simple way. Owing to the one-piece, i.e., material connection, optimum heat conduction properties are then obtained between the carrier structure in which the sorbent is incorporated and the wall. In a likewise preferred refinement, the adsorber is produced in the above-mentioned way partially or completely and additionally including the housing and further sorbate guides and heat carrier guides.
For the sorbent there are basically a plurality of suitable refinements which, in combination with the variants described above for the heat exchanger, each provide specific combinatorial advantages. A significant aspect here is the arrangement of the sorbent on the heat exchanger, in order to achieve the best possible contact.
In principle, it is possible to arrange zeolite as the sorbent and as an, in particular, spherical or sphere-like bulk material, i.e., in the form of a filler, around the heat exchanger and, for example, to secure it additionally by way of a securing net. However, this solution only generates punctiform contact with the outer surface of the heat exchanger and gives rise to a correspondingly low power density. Furthermore, this solution is unfavorable in terms of mechanical criteria and has, in particular, poor stability with respect to vibrations. Nevertheless, the use of bulk material in combination with the improved heat exchangers described above permits in the first place an efficiency level of the adsorber which is sufficient for the automotive field. Filling is performed here, in particular, in such a way that for example 2 to 3 layers of balls or filler bodies are arranged on the outer surface, wherein the balls each have a central diameter of approximately 0.3 to 2 mm. The filler is distinguished, in particular, by a high heat storage capacity and with respect to this criteria is also basically suitable for use in a vehicle.
An improved contact is achieved in one advantageous variant by virtue of the fact that the sorbent is embodied as a number of molded parts which are arranged, in particular in an exactly fitting fashion, on the heat exchanger. The sorbent is therefore specifically not embodied as a loose bulk material but is instead shaped in such a way that the sorbent can be applied in a particularly exactly fitting fashion, in particular in a positively engaging fashion, on the heat exchanger. As a result, the contact surface is improved significantly and the available volume is filled with sorbent and utilized to an optimum degree.
In a further particularly advantageous variant, the sorbent is applied as a direct coating, referred to for short as coating, to the heat exchanger, as a result of which particularly good contact is ensured between the sorbent and the heat exchanger. The coating has here, in particular, a thickness in the range from 0.05 to 1.5 mm. The coating is produced, for example, on the basis of a paste which is applied to the wall and cured there. Alternatively, a combination of the bulk material mentioned above with an adhesive or a binding agent is suitable for forming an, in particular continuous, coating, wherein the sorbent then fills, in particular, parts of the intermediate spaces between the bulk material. The embodiment of the sorbent as a coating has, in particular, the advantage that the sorbent is connected to the heat exchanger in a particularly fixed and stable fashion, and the adsorber therefore has lower susceptibility to vibrations and is therefore particularly suitable for use in a vehicle. In addition, in particular comparatively costly attachment by way of a soldering process or a securing net is then unnecessary, with the result that the production of the adsorber is also correspondingly simplified.
In a first advantageous refinement, the direct coating is applied by means of an immersion bath, wherein the heat exchanger to be coated or the carrier structure to be coated is immersed in the immersion bath, and the sorbent is then deposited. In this context, part of the material of the heat exchanger then advantageously merges with the coating, with the result that a particularly secure, material, and therefore materially joined, connection is produced.
A second refinement in which the direct coating is applied by way of crystallization to the heat exchanger, e.g., also in an immersion bath, is particularly preferred. Here, the sorbent or portions of the sorbent are preferably deposited uniformly on the outer surface, and in the process become connected, in particular securely, to the material of the wall. Particularly when a zeolite and a heat exchanger made of aluminum are used, the coating connects in a materially joined fashion to the wall by virtue of the fact that aluminum from the wall is introduced into the coating during the crystallization. The sorbent and the heat exchanger are then embodied in one piece, as a result of which optimum heat conduction between the sorbent and heat exchanger is ensured. Such coating is additionally particularly stable and is therefore particularly suitable for an adsorber which is used in a vehicle. In particular, the embodiment of the heat exchanger with a porous carrier structure is suitable for the application of a direct coating, since in this context the greatly enlarged outer surface is utilized particularly efficiently, and a particularly compact adsorber with a high power density is implemented.
The direct coating is also suitable with the carrier structure described above in an embodiment as a fiber bundle. In this context, the individual fibers or the entire fiber bundle are provided with a coating composed of sorbent, wherein, in particular, the selection of material described above also provides the specified advantages here.
The direct coating and generally the coating are alternatively produced by spraying the sorbate onto a surface, wherein a good connection, in particular after a curing process or drying process, is achieved.
In an alternative and also advantageous method, a molded part composed of sorbent is formed by compacting a carrier structure with powderous sorbent, i.e., the sorbent in powder form. A molded part which is produced in this way is also referred to as a combined molded part, since it is a combination of the sorbent and the carrier structure.
This method is particularly suitable for compacting fibers of a fiber bundle. In this context, the powderous sorbent is arranged in a suitable mold, and the fibers are scattered, placed or drawn into the sorbent. The portion of the fibers is preferably approximately 5 to 25% by volume here; the rest is, in particular, sorbent. This arrangement is then compacted, with the result that a combined molded part is formed which has fibers running through it. This combined molded part then has an improved thermal conductivity compared to a molded part fabricated solely from sorbent, owing to the additional fibers. Basically, an application of this method to other carrier structures is also advantageous. The combined molded part is then, for example, adhered to the heat exchanger, for the purpose of securement and thermal connection.
For further improvement, in one advantageous development a number of channels are then introduced, for example drilled, into the compacted sorbent, that is to say in the combined molded part. The channels then act during operation, in particular, as gas channels for the sorbate, with the result that the incorporation and release of the sorbate is significantly simplified. Such a combined molded part with channels is then preferably used in any refinements of the adsorber with the sorbent as a molded part, instead of a conventional molded part.
In a suitable variant, the powderous sorbent is pressed directly onto the heat exchanger, or compacted around it, with the fibers incorporated in said sorbent, generally the incorporated carrier structure. In this context, both a tubular heat exchanger and a tube bundle heat exchanger are suitable as a starting point for this method. Compaction of the sorbent with the heat exchanger and without a carrier structure is also advantageous, in particular in the case of a heat exchanger which has a number of lamellas.
A particularly efficient and high-performance adsorber is implemented in one preferred refinement by virtue of the fact that the sorbent is present in at least two different configurations which are selected from a group of configurations. Such a group may include, e.g., sorbent as filler; sorbent as coating; sorbent as a molded part; sorbent on a carrier structure; sorbent with a carrier structure as a combined molded part; and/or sorbent which is compacted together with the heat exchanger, i.e., in particular sorbent as a combined molded part which is compacted together with the heat exchanger. These configurations have already been described above, but have further advantages in combination. For example, the combination of different configurations permits optimum configuration of the power density and of the heat storage capacity of the adsorber. This is based on the realization that a sorbent which is embodied e.g., as bulk material or as a molded part, has, owing to the associated solidity, a particularly high heat storage capacity, i.e., energy density, while the use of e.g., a carrier structure and/or of a direct coating is of considerable advantage for the dynamics, i.e., the power density of the adsorber. An adsorber which is particularly suitable for the automotive field can then be implemented by combining these two advantages.
In one suitable refinement, for this purpose, on the wall and/or, if appropriate, between the lamellas of a heat exchanger in a first, near region, i.e., near to the wall, the sorbent is embodied as a direct coating, either directly on the wall and/or the lamellas and/or on a carrier structure which is arranged between the lamellas, e.g., an aluminum foam. In a second, distant region further away from the wall, the sorbent is then arranged as a molded part and/or as bulk material and/or a coated or compacted fiber bundle is arranged. As a result of the direct coating which is arranged near to the wall, high dynamics are then made available during the conduction of heat, which dynamics are particularly advantageous during operation and during the periodic adsorption and desorption. In contrast, the solid sorbent, which is located further toward the outside, makes available a high heat storage capacity which is advantageous, in particular, in the case of operational interruptions and subsequent cold starts of the vehicle, since this solid sorbent stores heat densely in terms of energy over a relatively long time period, for example several hours or days.
In one exemplary and preferred refinement, the heat exchanger is embodied with lamellas of different lengths, wherein in the near region which is then more densely fitted with lamellas, a coating composed of sorbent is applied, and in the distant region into which only a subset of the lamellas projects, the sorbent is arranged in a configuration as bulk material, or a number of fiber bundles or an aluminum foam, which are each coated with sorbent.
In further advantageous refinements with the sorbent in two different configurations, firstly a direct coating is applied to the heat exchanger, in particular by way of crystallization, and subsequently additional sorbent is arranged, in particular as bulk material, and the sorbent is then connected in a materially joined fashion to the direct coating by subjecting the entire arrangement composed of the direct coating and additional sorbent to crystallization, e.g., in an immersion bath, during which crystallization the additional sorbent is, as it were, baked with the direct coating and integrated therein thermally and mechanically. This brings about a particularly stable arrangement of the two configurations of the sorbent simultaneously. This combination therefore also permits the use of bulk material, wherein the original disadvantage of the lack of resistance to vibrations is eliminated by the materially joined connection to the coating. The same advantages result in an analogous fashion when a coating is combined with a number of molded parts by crystallization.
In one suitable variant, in the refinement described above the initial direct coating is omitted and the sorbent is merely arranged as bulk material or as a molded part on the heat exchanger and is then subjected to direct coating by way of an immersion bath or crystallization.
Generally, the combination of two different configurations of the sorbent therefore results in an adsorber which has high dynamics during operation and at the same time also a high heat storage capacity.
The sorbate which is used in a respective configuration, or else the material from which the sorbent is composed, is expediently selected as a function of this configuration. This is based on the realization that certain materials, in particular zeolites, are particularly suitable for certain configurations. In particular in conjunction with water as the sorbate, for example zeolite of the type NaY or 13X is suitable e.g., as a bulk material for a desorption temperature of e.g., above 160° C. and zeolite of the type SAPO34 is suitable e.g., for direct coating by way of crystallization for a desorption temperature of e.g., below 160° C.
The adsorber is expediently embodied overall in such a way that it can be integrated into another component of the vehicle, or that another component of the vehicle is integrated into the adsorber. This other component is here, in particular, a component of an adsorption system of the vehicle, for example a vaporizer, a condenser, an auxiliary heater, a valve for controlling the guiding of the heat medium, a switching valve or a flap valve or non-return valve, for controlling the guiding of the sorbate, i.e., for example, water vapor. The component is suitably thermally decoupled from the adsorber here, for example by way of air gaps or interruptions in the housing. In this way, in particular the power density of the entire adsorption system is increased.
In a further expedient refinement, a sensor or state sensor is integrated into the adsorber as a component. Said sensor is, for example, a temperature sensor, a pressure sensor or a combination sensor or a sensor for determining the sorbate concentration in the adsorber space and generally, in particular, a sensor for detecting a state of the adsorber. This is based on the concept that dynamically changing requirements are made of the operation of the adsorber particularly in the automotive field, and it is not possible to estimate the state purely on the basis of a known charging and discharging curve for the incorporation and release of the sorbate. Instead, it is to be assumed that during dynamic operation, the adsorption and the desorption take place differently depending on the requirements and demand, e.g., with respect to the dynamic adaptation of the operating point of the adsorption system, and therefore a measurement of the state, e.g., of the sorbate concentration in the adsorber space, is then correspondingly advantageous.
Alternatively or additionally, it is also expedient to integrate a position pickup into the adsorber as a component, by way of which position pickup a position of, in particular, passive, i.e., non-actively open-loop or closed-loop controlled valves, for example vapor valves or non-return valves, is detected during operation. By detecting and, in particular, monitoring the position, it is then possible to derive further information about the state of the adsorber.
Overall, the state is then advantageously monitored by integrating one or more sensors and/or position pickups. For this purpose, in particular, a control unit is also arranged, also referred to as a controller, or the sensors and/or position pickups are connected to a suitable control unit of the vehicle, with the result that optimum monitoring of the state takes place and, if appropriate, the adsorber or the adsorption system of the vehicle is controlled as efficiently as possible. In this context, particularly the switching over of the adsorber between adsorption and desorption is of interest. In order to achieve optimum use, in particular in terms of performance, of the existing heat storage capacity, a switchover time is advantageously determined on the basis of the detected state of the adsorber, with the result that the adsorber is switched over exactly at the correct moment.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.
The wall 8 and the housing 4 enclose an adsorber space 12, which is additionally accessible via at least one feedline 14. The adsorber 2 is additionally connected to the adsorption system also via the feedline 14. In order to store heat and to implement the essential functionality of the adsorber 2, a sorbate 16 is then arranged on the heat exchanger 6, as well as a sorbent 16 which is initially present here in a gaseous state in the adsorber space 12. The sorbate 18 is arranged on the heat exchanger 6, to be more precise on an outer surface 20 of the heat exchanger 6, and is in contact therewith, with the result that particularly efficient conduction of heat between the wall 8 and the sorbate 16 is ensured.
During the outputting of heat, i.e., during the discharging of heat from the adsorber 2, cold heat medium is guided through the heat exchanger 6, which heat medium picks up heat via the wall 8, which heat is generated by adsorption of sorbate 18 into the sorbent 16. Conversely, during the storage of heat, i.e., during the charging of the adsorber 2 with heat, heat is extracted from the heat medium, and the sorbent 16 is desorbed, i.e., sorbate 18 which is incorporated in the sorbent 16 is released and output into the adsorber space 12. Discharging of sorbate 18 from the adsorber space 12, and feeding sorbate 18 into said adsorber space 12 are then possible via the feedline 14, with the result that, for example, excess sorbate 18 can be fed to a reservoir (not illustrated). Any lines, reservoirs and housings which are connected to the feedline 14 then form, with the adsorber space 12, in particular a system which is closed off in a gas-tight and pressure-tight fashion. The sorbent 16 is, in particular, a zeolite, and the sorbate 18 is, in particular, water or a water/anti-freezing agent mixture, e.g., a water/glycol mixture.
On the one hand, the contact between the wall 8, to be more precise between the outer surface 20 and the sorbent 16, and, on the other hand, the accessibility of the sorbent 16 for the sorbate 18 for the purpose of adsorption and desorption are of essential significance for the performance capability of the adsorber 2. A significant improvement in the performance capability is then achieved, in particular, by way of suitable configuration of the heat exchanger 6 in general and of the outer surface 20 in particular, and by way of a suitable configuration of the sorbent 16 and suitable arrangement thereof on the wall 8.
The heat exchanger 6 shown in
In
In contrast, in the distant region 24b, a fiber bundle 28 with a plurality of fibers 30 is arranged between in each case two adjacent, long lamellas 22b. The fibers 30 are in turn coated with sorbent 16. A respective fiber bundle 28 constitutes here a carrier structure 32 which has, owing to the fibers 30, a particularly large surface on which, on the one hand, a particularly large amount of sorbent 16 can be arranged and which, on the other hand, permits a good flow of sorbate 18 through the fiber bundle 28. Overall, through this embodiment with two different configurations, an adsorber 2 is implemented which has both a high power density and therefore high dynamics during the exchange of heat, and a high heat storage capacity. The particular power density is generated here predominantly by the improved contact of the direct coating 26 in the near region 24a, while the particular heat storage capacity is generated predominantly by the large mass of sorbent 16 in the distant region 24b, wherein the fibers 30 permit good feeding in and discharging of heat, and the intermediate spaces permit a good throughflow of sorbate 18.
In a variant (not shown), in the distant region 24b there is no fiber bundle 30 arranged but instead another carrier structure 32 which is embodied, for example, as a sponge and preferably made from aluminum, and is coated with sorbent 16. Such a sponge and generally a porous carrier structure 32 are also suitable, owing to the good heat conduction, for arrangement in the near region 24a. In a further variant (not shown), in the distant region 24b, it is only the case that sorbent 16 is arranged as bulk material or as a molded part, which sorbent 16 can then absorb a correspondingly large amount of sorbate 18 and as a result has a particularly high heat storage capacity.
In a further variant, a respective different material is also used as the sorbent 16 in the different configurations, for example a zeolite of the type SAPO34 is used as the sorbent 16 for the direct coating 26, while a zeolite of the type 13X or NaY is used as the sorbent 16 in the form of bulk material.
The carrier structure 32 itself is produced in
The cavities 34 are preferably produced by way of a sacrificial material in the form of spherical bulk material, with the result that the cavities 34 are basically spherical or essentially spherical and each have a specific diameter D. As illustrated in
Before the compaction, the sorbent 16, e.g., as a powder, and the fibers 30 are arranged in a suitable mold and the arrangement is subsequently compacted to form the combined molded part 36. In order then to permit efficient penetration of sorbate 18 during operation, a number of channels 38 are additionally introduced, for example drilled, into the combined molded part. In the exemplary embodiment in
The exemplary embodiments which are shown in
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 219 688.7 | Oct 2015 | DE | national |
This application is a continuation of PCT International Application No. PCT/EP2016/073736, filed Oct. 5, 2016, which claims priority under 35 U.S.C. § 119 from German Patent Application No. 10 2015 219 688.7, filed Oct. 12, 2015, the entire disclosures of which are herein expressly incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2016/073736 | Oct 2016 | US |
| Child | 15949550 | US |
