Ice bank and method for assembling the same

Abstract

The invention relates to an ice storage device with a hollow, circular cylindrical base (1) in which heat exchanger tubes (11) are arranged as heat exchangers, in which a heat exchanger fluid is guided to exchange heat with a second heat exchanger fluid located in the base (1), wherein the heat exchanger tubes (11) are supported on the base (1) only by vertical supports (12). Furthermore, a method for assembling an ice storage device according to one of the preceding claims is shown, wherein the vertical supports (12) and the heat exchanger tubes (11) are mounted radially from the inside out.

Description

[0001] The invention relates to an ice storage unit or an ice storage heat exchanger or a corresponding construction with a hollow base body in which heat exchanger tubes are arranged as heat exchangers, in which a heat exchanger fluid is guided in order to exchange heat with a second heat exchanger fluid located in the base body, wherein a support structure for the heat exchanger tubes is provided, which has supports that are essentially aligned in the direction of gravity.

[0002] Ice storage heat exchangers, hereinafter referred to as ice storage systems, are typically divided into two categories: static ice storage systems and dynamic ice storage systems. In static ice storage systems, ice forms on heat exchanger tubes / coils or plates immersed in water and is stored there. In dynamic ice storage systems, the ice that forms on the surface of the heat exchanger tubes is harvested and stored in a separate container.

[0003] Ice storage systems can also be classified based on static and dynamic ice storage systems into: ▪ "Ice-on-Coil" (static ice storage) ▪ "Sheet Ice Harvester" (dynamic ice storage) ▪ "Encapsulated Ice" (static ice storage) ▪ "Ice Slurry" (dynamic ice storage)

[0004] In "frozen coil" ice storage systems, which are static ice storage systems, the heat exchanger fluid (water-additive mixture or evaporating refrigerant) flows through heat exchanger tubes called coils, and ice grows on the tube surface. These ice storage systems can be further divided into two different systems: one with an internal melt and one with an external melt.

[0005] In iced heat exchanger tubes with internal melting, the water is contained in a closed vessel, referred to as the base body. It therefore has no hydraulic connection to the building's cooling system. The heat exchanger fluid flowing through the heat exchanger tubes in this configuration is a water-additive mixture. During the charging process of the storage tank, the heat exchanger fluid flows into the heat exchanger tubes at a temperature below the freezing point of water. This causes ice to form on the tube surface. During the discharging process, i.e., during cooling or regeneration of the ice storage tank, the heat exchanger fluid flows into the ice storage tank warm, is cooled by the ice already present, and can then be fed into the building's cooling system. The ice thus melts from the inside out, hence the term "internal melting."

[0006] In the "Frozen Pipe Coils" ice storage system with external melting, either another pipe coil-based system is located within the ice storage tank, or water can be drawn from the ice storage tank. In the latter case, there is an open container that is hydraulically connected to the building's cooling system. The charging process of the ice storage tank is analogous to the variant with internal melting. During the discharging process, i.e., during cooling or regeneration, warm heat exchanger fluid flows through these pipe coils in the storage tank in the "External Pipe Coils" ice storage system, cools down, and can then be used for cooling purposes. The heat input from the warm heat exchanger fluid melts the ice from the outside. In the case of the open storage tank, the cold water is pumped out of the tank, passed through a plate heat exchanger, heated, and then returned to the ice storage tank.In this way, the ice also melts from the outside due to the heated water in the ice storage tank. Therefore, the term "external melting" is used for this type of storage management.

[0007] The charging and discharging interval of ice storage systems can be daily, weekly, or seasonal. Typically, the size of the ice storage system increases with longer intervals, as a higher thermal capacity is required.

[0008] Seasonal ice storage systems are used as a heat source for brine / water heat pumps and are frequently implemented in the "ice-on-coil" variant with internal or external melting. The base units are typically made of waterproof concrete, have a cylindrical shape, and are located underground near the building. A connecting pipe links the ice storage unit to the building housing the heat pumps. These pumps extract heat at a low temperature level from the heat exchanger fluid / storage medium, which is usually water, and raise it to a temperature suitable for building heating / domestic hot water preparation. For this purpose, the ice storage unit contains a so-called extraction heat exchanger, which enables the utilization of both the sensible and latent heat of the water.

[0009] Since the storage capacity is insufficient to supply the heat pumps with all the source energy during the heating season, a regeneration source is required. The heat provided by the regeneration source is fed into the ice storage tank over the course of the heating season. This requires a so-called regeneration heat exchanger within the ice storage tank. In the case of internal melting, the extraction heat exchanger also serves as the regeneration heat exchanger. Here, when heat is introduced into the storage tank, the ice on the pipe is heated or melted from the inside. In the case of external melting, a second heat exchanger is located within the ice storage tank, through which the heat is transferred. Here, when heat is introduced into the storage tank, the ice on the extraction heat exchanger is heated or melted from the outside.

[0010] The heat exchanger ice storage system thus functions at least as a heat extraction heat exchanger, in which heat transfer to the heat exchanger fluid is achieved. The injection of the heat exchanger fluid into the heat exchanger tubes is typically accomplished using external heat pumps. The injection of heat exchanger fluid into the heat exchanger tubes by the heat pump is referred to as the flow, and the direction of the heat exchanger fluid flow is called the flow direction.

[0011] In the further course of the presentation of the present technical invention, the extraction heat exchanger will be referred to simply as a heat exchanger, and a conceptual differentiation from the regeneration heat exchanger will thus be continued.

[0012] The heat exchanger used in ice storage systems to date, according to the state of the art, consists of a complex structure of heat exchanger levels arranged in a spiral within the ice storage system and connected at a manifold. The base is a stable frame construction made of aluminum or another corrosion-resistant material. First, vertical supports are installed within the heat exchanger-ice storage system. Then, according to the state of the art, horizontal beams are installed between these supports. Finally, a heat exchanger tube, typically made of plastic, is fixed to each of these horizontal beams on a single level.

[0013] In accordance with current best practices, the pipes are laid exclusively on a horizontal plane in a spiral pattern and connected to the manifold. In this way, several levels of horizontal supports are constructed within the ice storage tank. The assembly process begins at the bottom of the ice storage tank with the first horizontal level and ends approximately 80 cm below the top of the tank, depending on its height. In the version with internal melting, this extraction heat exchanger also serves as a regeneration heat exchanger. In the version with external melting, the regeneration heat exchanger consists of a pipe system arranged in a helical pattern around the periphery of the ice storage tank (the so-called annular space). Supports are also installed within the ice storage tank for the regeneration heat exchanger.Finally, the heat transfer pipes / plastic pipes are attached to these supports as vertical concave pipe coils / heat exchanger pipes and also brought together at a distributor.

[0014] The current state of the art design of the heat exchanger in the ice storage tank has disadvantages, which can be summarized as follows, categorized as assembly, material usage, and thermodynamic properties: The heat exchanger levels are installed from bottom to top. The first few heat exchanger levels can be installed without difficulty, as the installation personnel can move around on the typically concrete floor of the ice storage tank's base. However, above a certain height, the installation personnel can no longer walk on the base of the ice storage tank. From this critical height onward, moving and installing the heat exchanger levels can only be accomplished using mobile floor segments placed on the aluminum supports. This method of movement and installation within the ice storage tank is not only time-consuming but also requires additional safety precautions due to working at height.

[0015] Furthermore, the existing ice storage heat exchanger design is very material-intensive due to the large number of aluminum supports, although this is necessary for its technical functionality. These aluminum supports primarily serve to absorb the forces and moments occurring during the continuous freezing process by transferring the buoyancy force of the ice block forming in the storage tank to the roof of the ice storage heat exchanger's base structure. They are therefore necessarily designed to be buckling-resistant. Secondarily, the aluminum supports accommodate the heat exchanger tubes, fixing them at calculated intervals within the ice storage tank and serving as a substructure for mobile floor segments during assembly.

[0016] The thermodynamic properties are not optimal due to the current arrangement of the heat exchanger tubes in the storage tank. During the charging process of the ice storage tank in the heating season (ice build-up), natural convection is the predominant mechanism of heat transfer within the core of the ice storage heat exchanger. The effect of the well-known thermal density inversion / density anomaly of water can be observed not only in the water temperatures but also in the heat exchanger fluid. Before ice formation begins, the warmest water collects at the bottom of the core of the ice storage heat exchanger, and the coldest water at the surface. As a result, the heat exchanger fluid in the lower heat exchanger levels heats up more than the heat exchanger fluid in the upper levels. Therefore, the upper heat exchanger levels exhibit a lower extraction rate than the lower levels in this operating range.The different water temperatures lead to uneven ice formation in the core of the ice storage heat exchanger. Since the coldest water temperatures are found at the surface, ice forms first on the upper heat exchanger levels and then slowly spreads downwards.

[0017] External melting via a regeneration heat exchanger leads to inefficient operation of the heat pump. This is due to two reasons. Firstly, with the same storage volume, the surface area for the extraction heat exchanger is smaller. This is because the regeneration heat exchanger, which is typically installed at the periphery of the ice storage heat exchanger, reduces the effective space available for the extraction heat exchanger. The extraction heat exchanger must therefore be built more compactly, resulting in smaller distances between the heat exchanger tubes. This causes the growing ice layer on the heat exchanger tubes to coalesce more quickly into a solid block of ice. This leads to a faster decrease in the brine outlet temperature from the ice storage and consequently to a lower coefficient of performance (COP) for the heat pump. Secondly, during regeneration, the heat input occurs from the periphery of the ice storage. The ice block is thus reheated or thawed from the outside.Once a solid block of ice has formed around the heat exchanger tubes of the extraction heat exchanger, the ice behaves like a large solid cylinder. This solid cylinder can be supercooled by further heat extraction. That is, the ice cylinder can be cooled far below the melting point of water. If the ice cylinder is then heated and thawed from the outside, temperatures well below freezing can still prevail inside, leading to poor performance figures for the heat pump and thus inefficient operation.

[0018] Against this background, the object of the present invention is to avoid or at least mitigate the disadvantages known from the prior art with regard to the assembly, the use of materials and the thermodynamic properties of the heat exchanger construction of the ice storage system.

[0019] In a typical ice storage system or heat exchanger construction of an ice storage system, this is solved by arranging the supports in such a way that they define concentric shells.

[0020] One could also say that in the heat exchanger design of a heat extraction heat exchanger implemented as an ice storage system with internal melting, only vertical supports are required to support the heat exchanger tubes of the heat exchanger-ice storage system. This allows for material savings and assembly advantages. Horizontal supports, which in previous ice storage system designs according to the prior art were provided for fixing the heat exchanger tubes (laid exclusively on a single horizontal plane) and for multiple horizontal planes, are no longer structurally necessary. According to the invention, the heat exchanger tubes are arranged in such a way that ice formation in the heat exchanger-ice storage system is specifically influenced.

[0021] In principle, the ice storage heat exchanger according to the invention only provides one heat exchanger, a so-called extraction heat exchanger, in the main body of the ice storage heat exchanger, thus constituting an ice storage system with internal melting. By eliminating the need for a second, so-called regeneration heat exchanger, the two challenges of the prior art that lead to inefficient operation of the heat pumps are eliminated. This counteracts, firstly, the loss of surface area caused by an additional regeneration heat exchanger that would have to be integrated into the ice storage system. Secondly, the heat extraction at the extraction heat exchanger, resulting in progressive subcooling of the interior of the ice block, and the thawing of the ice block from the outside / periphery via the regeneration heat exchanger cannot occur simultaneously.If a second heat exchanger is required, it can be installed in the ice storage tank's base body as before. The integration of the regeneration heat exchanger has no effect on the design of the internal extraction heat exchanger. The installation of the heat exchanger assembly according to the invention no longer takes place from bottom to top in the ice storage tank, as is the case in the prior art, but rather from the center to the outer wall of the ice storage tank / ice storage tank periphery, and thus, by definition, from the inside out. The center of the ice storage tank's base body does not necessarily have to correspond to the center of an ice storage tank heat exchanger assembly / support structure according to the invention.

[0022] In the context of explaining advantageous embodiments, the radial direction is defined as the direction along the radius of the ice storage unit's base and thus of the heat exchanger assembly. The circumferential direction is described by the circumference of the ice storage unit's base. The cylindrical direction lies at the height of the ice storage unit's base. The term "cylindrical plane" therefore refers to a horizontal plane of the ice storage unit's base that correlates with a specific height.

[0023] Advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0024] In connection with the ice storage heat exchanger construction / supporting structure, it is advantageous if the heat exchanger pipes are attached to the supports at connection points.

[0025] The supports are advantageously aligned in the direction of gravity. For a base body of the ice storage heat exchanger that is oriented horizontally to the Earth's surface, this implies a preferably vertical orientation of the supports. In accordance with the present invention, it is advantageous that, for a circular cylindrical base body, the supports are arranged in an annular pattern at predetermined intervals around the circumference of the base body. This annular arrangement of the supports accommodates the geometry of the base body of the ice storage heat exchanger, which is preferably circular. The positions of the supports are advantageously located on the circumference of the circular cylindrical base body, depending on its radius. By positioning the supports in an annular pattern at predetermined intervals, the technical advantage is realized that a base area (so-called...) is not required.The base of the ice storage unit is defined and preferably uniformly loaded with respect to the forces absorbed by the supports and transferred into or from the base during freezing. However, according to the invention, both the geometry of the base and the entire ice storage heat exchanger, as well as the advantageous geometric arrangement of the supports, are fundamentally variable to achieve the intended technical effect.

[0026] The number of supports required can advantageously be kept constant or scaled / adjusted depending on the distance from the center of the ice storage heat exchanger structure / support structure. The center of the ice storage heat exchanger structure according to the invention advantageously corresponds to the center of the base body of the ice storage heat exchanger. However, other centers are also conceivable. In the following explanations of the advantageous embodiments, the center will be referred to as the center of the ice storage heat exchanger structure according to the invention. For a preferably circular cylindrical base body of the ice storage system, the number of supports can either be kept constant or scaled / adjusted depending on the circumference of a horizontal circular plane and thus the radius.Compared to prior art heat exchanger designs, it is advantageous to provide a higher number of supports oriented in the direction of gravity, preferably vertical ones, so that the buoyancy forces of the ice block formed during discharge are distributed more homogeneously over the surface of the hollow, preferably circular cylindrical, base body, a so-called concrete container lid or bottom. The additional material required for the preferably vertical supports is advantageously less than the material required for horizontal supports according to the prior art, so that the inventive solution offers advantages with regard to saving the support material aluminum and the construction is more resource-efficient than the previously conventional design.

[0027] Because the preferably vertical and rigid supports perform the functions of transferring the buoyancy force of the ice block forming in the ice storage tank into the roof of the ice storage heat exchanger's base body and absorbing the forces and moments occurring during the continuous freezing process, fixing the heat exchanger tubes to these supports allows for a defined positioning of the heat exchanger tubes during operation of the ice storage heat exchanger. Furthermore, this fixing method advantageously facilitates the simple positioning of the heat exchanger tubes at predetermined, and if necessary, calculated, defined intervals in both horizontal and radial directions. This implies fixing the heat exchanger tubes relative to each other in the circumferential, radial, and vertical directions.The heat exchanger tubes, attached to the supports, which are preferably arranged in an annular and preferably vertically oriented, describe circular rings. The length of the supports is advantageously selected according to the height of the base body, i.e., the distance from its base to its top. In this way, it is technically advantageous to fix the supports to the base and top of the ice storage heat exchanger's base body using suitable connecting elements such as screws or dowels, either positively or non-positively, thus ensuring their position during operation of the ice storage heat exchanger and under the acting forces and moments.With regard to the heat exchanger tubes, a force-fit and / or form-fit fixing of the heat exchanger tubes to the supports using pipe clamps and screws is advantageous for protection against the effective buoyancy forces. This allows the heat exchanger tubes to be fixed via the screws using defined and reproducible preload forces, thus securing the position of the heat exchanger tubes even under load. Fixing the heat exchanger tubes using clamp connections, for example, is also conceivable. Clips, in particular, represent an advantageous embodiment for a locking device that is preferably detachable from the connection point and utilizes form-fit technology. This device is primarily made of plastic.The spacing of the individual supports arranged circumferentially is advantageously selected such that the segments of the heat exchanger tubes (circular segments) not directly supported or fixed to the supports have a sufficient length, depending on the selected tube material and the forces occurring during operation of the ice storage system. This ensures that the flow of the heat exchange fluid in the base of the ice storage system is not obstructed by, for example, hanging tube segments. The free length is advantageously designed taking into account the fluid, the forces acting upon it, as well as fluid mechanics, structural mechanics, and thermodynamic considerations. Other design criteria may also be applied.

[0028] Furthermore, it has proven advantageous that the heat exchanger tubes are fixed in position solely by means of the, preferably vertical, supports in the base body. This method of fixing the position of the heat exchanger tubes allows for savings in material resources, such as aluminum as the base material for the horizontal supports according to the prior art, which are no longer necessary according to the invention due to the multitude of preferably vertical supports. Moreover, assembly is technically advantageous and simplified, as only the supports and the associated connecting elements need to be provided and fastened.

[0029] Furthermore, it is advantageous if exactly one heat exchanger tube is arranged helically on a circular ring / horizontal plane on the, preferably vertical, supports, wherein a plurality of helixes formed by several heat exchanger tubes (12) describe a circular ring shell. The heat exchanger tube / convex tube helix extends on a horizontal plane with respect to the base body of the ice storage system and the ice storage-heat exchanger assembly / support structure over at least 180° and a maximum of 270° or even 360°. Once a circular ring of, preferably vertical, supports has been erected, it is advantageous to attach one heat exchanger tube to each circular ring. The arrangement of the heat exchanger tube is advantageously as a convex tube helix.

[0030] Alternatively or additionally, the heat exchanger tube can advantageously be arranged such that each heat exchanger tube extends beyond a horizontal plane and is arranged in a corkscrew-like fashion on the vertical supports. In connection with this particularly corkscrew-shaped / helical arrangement of the heat exchanger tubes, running from bottom to top, it is especially advantageous that a predetermined slope of the heat exchanger tubes is specified and set. The preferably continuous slope of the heat exchanger tubes enables automatic venting of the tubes, thereby preventing air pockets / cavities in the heat exchanger tubes and advantageously increasing the efficiency of the heat transfer and thus of the entire ice storage system. The slope is advantageously dependent on the diameter of the respective heat exchanger tube and continuous along the length of the tube.The automatic venting represents a significant advantage of the invention compared to the prior art. Furthermore, the helical or corkscrew-like routing of the heat exchanger tubes achieves technically advantageous stabilization effects. Deflection / sagging of the heat exchanger tubes is reduced, thereby further improving the flow characteristics. The pipe routing makes the ice storage heat exchanger structure more rigid, thus requiring less support material. In conjunction with the use of aluminum supports, savings of up to 50% in aluminum resources for ice storage heat exchanger structures compared to the prior art can be achieved.

[0031] With regard to the number of heat exchanger tubes arranged on the circular rings and the circular ring shells, it is also conceivable - and advantageous in the sense of the technical invention - if not just one, but several heat exchanger tubes are arranged on the circular ring.

[0032] With the assembly of the subsequent circular ring, preferably extending radially outwards, the next circular ring of heat exchanger tubes is integrated into the ice storage heat exchanger. In this way, circular ring after circular ring and circular ring shell after circular ring shell are assembled from the inside out. The heat exchanger tubes are generally designed as convex coils, although other arrangements and less uniform profiles are conceivable. By designing the heat exchanger tubes with the geometry of convex coils, a technical advantage can be achieved in that the heat transfer between a heat exchanger fluid and a surface of the heat exchanger tube / coil is advantageously increased compared to a straight tube due to the secondary flow in the form of a double vortex, which can be realized as a result of centrifugal forces.This is accompanied by an increased Nusselt number as a result of the curvature of the heat exchanger tube, which serves as an indicator of the increased convective heat transfer between the surface of the heat exchanger tube and the heat exchanger fluid.

[0033] The radial spacing of the individual circular rings is advantageously determined such that the distances between the heat exchanger tubes are advantageously large, allowing the ice layer growing on the heat exchanger tubes to coalesce into a solid block of ice at an advantageously slow rate. This advantageously controls the rate at which unfavorably lower brine outlet temperatures are reached from the ice storage tank, thus preventing unfavorably lower performance figures for the heat pump. Adjacent circular rings can advantageously be arranged to form so-called circular ring shells. The combination of approximately six individual circular rings into a circular ring shell has proven advantageous in this regard. A radial mounting distance of 10 to 15 cm has proven advantageous for arranging the circular rings.Furthermore, in connection with the heat exchanger tubes, the use of state-of-the-art plastic tubes has proven advantageous in terms of corrosion resistance, flexibility and durability.

[0034] Furthermore, it is advantageous that the distributor switches the supply of the heat exchanger fluid to the heat exchanger tubes depending on the individual circular rings / horizontal planes and that the position of the heat exchanger tubes can be configured variably.

[0035] In connection with the mounting of a heat exchanger tube / convex coil onto the supports of the circular ring, it is advantageous, with regard to accessibility, installation effort, and occupational safety, to connect the heat exchanger tube directly to a manifold for the heat transfer fluid after mounting. The manifold is preferably designed to be lockable. The manifold can advantageously be made of plastic pipe. Furthermore, the manifold is advantageously configured to be fluidically connected to an external heat pump for heat exchange via the heat transfer fluid.By connecting to the heat exchanger pipe manifold in the sense of a heat exchanger fluid manifold / distributor, the fluidic connection with an external heat pump can be advantageously realized in order to exchange heat with it via the heat exchanger fluid. The position of the heat exchanger pipes can be advantageously configured variably in the vertical direction of the base body.

[0036] Furthermore, the coil geometry of the heat exchanger tubes allows for advantageously flexible configuration of the heat exchanger fluid inflow. By arranging the heat exchanger tubes advantageously as a convex coil, it is advantageously possible to concentrate the inflow of the heat exchanger fluid in local areas of the base body of the ice storage heat exchanger. This advantageously implies that the inflow point of the heat exchanger fluid supplied via the distributor is variable in the heat exchanger tubes, which are preferably designed as convex coils, such that the heat exchanger fluid can enter the respective heat exchanger tube of the ice storage heat exchanger from either the top or the bottom of the convex coil / heat exchanger tube.The position of the inflow, whether from above or below, defines the flow direction of the fluid and thus the supply direction. The designations "above" and "below" refer to the ice storage system's construction. The area of ​​the ice storage system closest to the bottom is located at the bottom. The area closer to the lid, and therefore closer to the surface, is located at the top. If the supply enters the heat transfer pipe / convex coil from below, the supply configuration is "supply below." If the supply enters from above, the configuration is "supply above." According to the invention, the configuration for the individual heat exchanger tubes of the circular rings is variably selectable.According to the invention, the heat exchanger tubes of the individual circular rings can have identical or different configurations compared to one another, so that a distinction is preferably made between the configurations "flow at bottom", "flow at top", and "alternating flow" across circular rings and circular shells. While in the configurations "flow at bottom" and "flow at top" the flow is the same in all heat exchanger tubes of the ice storage system, in the configuration "alternating flow" differences in the flow direction between the heat exchanger tubes of the individual circular rings and, advantageously, in radially successive circular rings are implemented. In this sense, it is advantageously possible for the tube coils to be guided alternately in the base body of the ice storage system.Furthermore, other consequences of the configurations of the flow for successive and non-successive heat exchanger tubes are also conceivable in principle.

[0037] By strategically designing the flow path in the heat exchanger tubes of the cylindrical base of the ice storage system, advantages and control over the speed and direction of ice formation can be achieved. Furthermore, various operational requirements of the ice storage system can be advantageously addressed by utilizing the thermal density inversion / density anomaly of water. This approach improves the overall heat transfer capacity of the ice storage heat exchanger.

[0038] To delay ice formation on the heat exchanger tube for as long as possible, for example to increase the heat transfer capacity of the ice storage heat exchanger and thus also the efficiency of the entire ice storage system, a flow configuration is advantageous in which the flow of the heat exchanger fluid of the ice storage heat exchanger is directed in the lower part of the ice storage system in the sense of the "flow at the bottom" configuration.Due to the water located in the lower part of the cylindrical base of the ice storage heat exchanger, resulting from a density anomaly / density inversion of the water, the routing of the flow in this area advantageously ensures that the heat exchanger fluid with the coldest temperature comes into contact with the water in the base of the ice storage heat exchanger with the warmest temperature via the heat exchanger tubes, and an advantageously high heat transfer is achieved without necessarily causing ice formation.

[0039] In contrast, with regard to accelerated ice formation on the heat exchanger tubes, which is advantageous in specific applications, it has proven beneficial to arrange the tube coils in the upper sections of the base body in a "flow direction at the top" configuration. Due to the less dense, colder water layers in the upper section of the ice storage tank resulting from a density anomaly / density inversion, the flow of the heat exchanger fluid into the heat exchanger tubes located in the upper section of the base body (in a so-called flow direction) ensures that the coldest temperature of the heat exchanger fluid in the heat exchanger tubes is surrounded by the coldest temperature of the water in the ice storage tank. The resulting accelerated ice formation is advantageous when using the ice storage tank as a pure cold storage unit.This is especially true since ice storage facilities are often only iced up to a small percentage, so it is not crucial where ice formation starts.

[0040] In contrast, an alternating configuration with alternating flow and the associated orientation of the heat exchanger tubes / convex coil, characterized by the alternating sequence of "flow at the top" and "flow at the bottom," results in the ice fronts on the heat exchanger tubes merging at the last possible moment, since ice formation due to the alternating flow is not homogeneous but conical. The shape of this so-called ice cone is determined by the temperature profile in the heat exchanger tube from inlet to outlet. Due to the exponential temperature of the heat exchanger fluid, the ice thickness on the heat exchanger tube decreases in a similar pattern. Thus, the alternating flow arrangement advantageously ensures that the ice thicknesses of greatest and smallest are always opposite each other during ice formation.This configuration can be advantageous if the ice storage volume is very compact, the distances between the pipes are very small, and the icing of the ice storage is to be advantageously delayed.

[0041] Furthermore, it is advantageous that the curvature of the heat exchanger tubes decreases radially outwards from the center of the ice storage unit (the ice storage-heat exchanger assembly / support structure). By decreasing the curvature of the heat exchanger tubes, arranged as coils, with the radius and thus radially outwards from the center of the ice storage-heat exchanger assembly / support structure, the heat transfer capacity of the heat exchanger tubes can be advantageously reduced with increasing distance from the center of the ice storage unit. This implies that, despite the same tube length, the heat transfer capacity of the inner heat exchanger tubes / coils is advantageously higher than that of the outer heat exchanger tubes / coils due to their higher Nusselt number.This design of the heat exchanger tubes allows the direction of ice formation to be advantageously influenced. Thus, when the ice storage system is discharged, ice formation advantageously begins in its center, at the bottom, before progressing to the outer area of ​​the ice storage structure.

[0042] It is also advantageous that several annular shells are arranged consecutively. Several of these annular shells are arranged radially to fill the base of the ice storage heat exchanger, with assembly proceeding from the inside out for ease of installation and safety. This inside-out assembly allows the installation personnel to work with a firm footing on the base of the cylindrical body at all times. Depending on the storage height, it may also be advantageous to use a ladder or rolling scaffold as an installation aid. Furthermore, access to an entry shaft located on the outer circumference or outer wall of the cylindrical body is freely available at all times during installation, thus providing a convenient escape route for the installation personnel, thus enhancing workplace safety.The free space within the cylindrical base, and especially on the bottom of the ice storage unit, can be advantageously used as a storage area during assembly. The number of annular shells required depends primarily on the dimensions of the cylindrical base and thus its diameter.

[0043] In connection with the technical invention, it has also proven advantageous that the shells are arranged at uneven intervals around a common center or at different intervals around a common center. The uneven or different spacing between the annular shells, and especially between the annular rings they contain, makes it advantageously possible to adjust the spacing depending on the respective heat transfer capacity of the individual coils as a function of curvature / radial position, ice formation dynamics, or other thermodynamic, fluid-mechanical, or assembly-related considerations. As already explained in connection with other advantageous embodiments, the center of the ice storage heat exchanger structure / supporting structure can coincide with the center of the ice storage base.However, the centers can also be arranged at any distance from each other or in a predetermined ratio to each other. Regardless of the features of the patent claims, it is also possible to implement the invention separately as an ice storage system with trays according to claims 1 to 5 and to discard this additional feature. The feature of varying the distance is not essential for this variant.

[0044] Furthermore, it is advantageous if, after a predefined number of shells, there is a greater distance between two shells than between at least two subsequent shells. This greater distance is advantageously designed in the form of a gap that can be used as an inspection opening. It has proven advantageous to provide a gap of approximately 50 cm between the individual annular shells in order to allow access to all installed pipes for inspection purposes.

[0045] In the event that a regeneration heat exchanger is required in addition to the extraction heat exchanger, the regeneration heat exchanger can be installed in the base body of the ice storage heat exchanger according to the prior art, without affecting the design of the inner extraction heat exchanger according to the invention shown.

[0046] In connection with the ice storage heat exchanger construction / support structure according to the invention, an assembly method has proven advantageous as part of the invention. Here, supports define the ice storage heat exchanger construction / support structure as concentric shells, with at least two heat exchanger tubes running in different planes and attached to the supports, starting at the supports that define the innermost shell. The heat exchanger tubes are mounted radially from the inside out according to the method.

[0047] Furthermore, a method for operating the ice storage system has proven advantageous in which the coldest area at the bottom of one of the inner shells is specifically created to achieve almost complete icing, or the coldest area in the inner shell furthest from the bottom is specifically created to achieve rapid but incomplete icing in the long term. It is advantageous if the coldest area at the bottom is created by one or more—preferably three to five—of the inner shells, or by the innermost shell. It is particularly efficient if at least one pipe, selected pipes, or all pipes are designed according to the patent granted to the applicant DE 10 2019 121 166 B4.

[0048] The invention is explained in more detail below with the aid of drawings. Various embodiments of the invention are shown in more detail. The drawings show: Fig .1 an ice storage heat exchanger design according to the state of the art in a perspective partial view, Fig. 2 an ice storage heat exchanger construction / support structure according to the invention with a circular cylindrical base body in a top view, Fig. 3 a section of an ice storage heat exchanger construction / support structure according to the invention in a side view in a first embodiment with a circular cylindrical base body, Fig. 4 a section of an ice storage heat exchanger construction / support structure according to the invention in a side view in a second embodiment with a circular cylindrical base body, Fig. 5 a section of an ice storage heat exchanger construction / support structure according to the invention in a side view in a first embodiment with a circular cylindrical base body, Fig. 6 a graphical representation of measurement results as a function of temperature over time for a cooling experiment of water for a "bottom feed" configuration and Fig. 7 A graphical representation of measurement results as a function of temperature over time for a cooling experiment of water for a "top feed" configuration.

[0049] The figures are purely schematic and serve only to illustrate the invention. The same elements are identified by the same reference symbols.

[0050] In the Fig. 1 Figure 1 depicts an ice storage heat exchanger design according to the prior art. The ice storage unit is designed as a extraction heat exchanger with an integrated regeneration heat exchanger. Aluminum supports 2 are arranged vertically on the inner surface of a circular cylindrical base 1 made of concrete for the ice storage heat exchanger, in accordance with the prior art for ice storage regeneration heat exchangers. Plastic pipes are attached to these aluminum supports 2, extending towards the center 3 of the heat exchanger-ice storage unit, for heat transfer. These pipes are arranged circumferentially and thus concentrically to the center 3 of the ice storage heat exchanger. The regeneration heat exchanger surrounds the extraction heat exchanger.According to the prior art, the extraction heat exchanger is characterized by a centrally located vertical aluminum support 5, from which horizontal aluminum beams 6 extend radially or star-shaped at approximately 30° intervals, reaching vertical aluminum beams 7 of the extraction heat exchanger at the edge of the ice storage heat exchanger structure. At the ends of the horizontal aluminum beams 6, vertical aluminum beams 7 form the frame for the extraction heat exchanger of the ice storage heat exchanger structure. Spirally arranged plastic tubes 8 of the extraction heat exchanger are mounted on the horizontal aluminum beams 6 in the horizontal plane. This configuration is repeated on various horizontal planes. Assembly is carried out from bottom to top.

[0051] In the Fig. 2 The walls 9 and base 10 of a circular cylindrical base body 1 of an ice storage heat exchanger according to the invention are shown. An ice storage heat exchanger structure / support structure 11 according to the invention, with heat exchanger tubes 12 in a first embodiment, shown in a top view, is arranged within these. Vertical supports 13 (appearing as points in the top view) are visible, arranged in circular rings 14, on which heat exchanger tubes 12, in the form of plastic tubes, are attached. Five circular rings 14 are arranged to form a circular ring shell 15. Starting from the center 3 of the ice storage heat exchanger structure / support structure 11, five circular ring shells 15 are arranged successively in the radial direction. The circular ring shells 15 are interrupted by a gap 16, which is advantageous for accessing the heat exchanger tubes 12 for maintenance purposes.The radial length of the gap 16 and its variation for the individual annular shells 15 are variable according to the invention, but can also be uniform. The curvature of the heat exchanger tubes 12 decreases radially from the center 3 of the ice storage heat exchanger assembly / support structure 11. As a consequence of the decreasing Nusselt number with decreasing curvature of the heat exchanger tubes 12, the heat transfer capacity of the heat exchanger tubes 12 decreases radially, causing ice formation to begin in the center 3 of the ice storage heat exchanger assembly / support structure 11 and progress radially. Five annular shells 15 are arranged successively in the radial direction, starting from the center 3 of the ice storage heat exchanger assembly / support structure 11. The heat exchanger tubes 8 are connected to a lockable manifold 17.In contrast to the circular cylindrical shape of the base body 1, other basic shapes, and in particular non-rotationally symmetrical ones, are conceivable. Further variations are possible with regard to the material of the heat exchanger tubes 12, which are made of plastic according to the prior art. Compared to the aluminum construction of the vertical supports 13, the use of other materials is also conceivable. In the illustrated embodiment, the vertical supports 13 of the respective circular rings 14 are arranged at the same positions circumferentially within a circular ring shell 15. A comparison of the circular rings 14, separated from each other by a gap 16, reveals that in the illustrated embodiment the vertical supports 13 are arranged at different positions circumferentially.Both in connection with the position of the vertical supports 13 in an annular shell 15 and in connection with the relative position of the vertical supports 13 of different annular shells 15 to each other, other embodiments with varying distances are explicitly conceivable and possible. By varying the distance of the vertical supports 13 in the circumferential direction, the length of a circular segment 18 guided between two vertical supports 13 is fundamentally variable. The distances shown as equal in the radial direction, which characterize a gap 16, can also be implemented in a variable manner or designed according to the distance between the annular rings 14. In connection with the shape of the arrangement of the heat exchanger tubes 12 as plastic tubes arranged concentrically to the center 3 of the ice storage heat exchanger construction / support structure 11, other embodiments are also fundamentally conceivable.

[0052] In the Fig. 3 Figure 1 shows a side view of an ice storage heat exchanger construction according to the invention in a first embodiment with a circular cylindrical base body 1. The ice storage heat exchanger according to the invention is designed as a plastic pipe extraction / regeneration heat exchanger. Vertically oriented supports 13 made of aluminum are visible, arranged concentrically to the center 3 of the ice storage heat exchanger construction / support structure 11 and also to the base body 1 of the ice storage heat exchanger. The vertical supports 13 are rigidly connected to the bottom 11 and the top / lid 19 of the circular cylindrical base body 1 of the ice storage heat exchanger. The arrangement of the vertical supports 13 is radial from the inside out, thus extending from the center 3 of the ice storage heat exchanger construction / support structure 11.A predetermined distance is provided between the vertical supports 13 in both the radial and circumferential directions. After four consecutive vertical supports 13 in the radial direction, a larger distance is implemented, for example, for maintenance purposes. This distance can be provided in the form of a gap 16. Omission of the gap 16 and varying gap lengths are also conceivable. The radial distance between the vertical supports 13 can be uniform or vary. Plastic pipes, serving as heat exchanger pipes 12, are arranged on the vertical supports 13, oriented towards the center 3 of the heat exchanger-ice storage structure / supporting structure 11. Alternative shapes of the base body 1, and in particular non-rotationally symmetrical shapes, are generally conceivable.The center 3 of the ice storage heat exchanger assembly and the center point / centroid of the base of the base body 1 are identical for the illustrated embodiment, but need not be so according to the invention in further embodiments. Also visible in the illustration are the heat pump-side pipes 20, which carry the heat transfer fluid and belong to the heat pump. These pipes are provided for supplying the distributor 17 and for the flow 21 and return of the heat exchanger fluid.

[0053] In the Fig. 4 Figure 1 shows a section of an ice storage heat exchanger construction / support structure according to the invention in a side view, in a second embodiment with a circular cylindrical base body 1. In this embodiment, in contrast to the one shown in Figure 2, the following features are used: Fig. 3 In the illustrated embodiment, the heat exchanger tubes 12, which are made of plastic, are attached to the outside of the vertical aluminum supports 13 at a connection point 22, on the sides oriented towards the walls 9 of the base body 1. The attachment is achieved by guiding a connection system in a recess / groove in the vertical support 13. This connection system consists of a groove-side connection element and a form-fit and / or force-fit connection element relating to the heat exchanger tube 12. Form-fit, force-fit, or material-fit alternatives to the illustrated connection system are conceivable. It can be seen that six circular rings 14, which have a predetermined distance from each other, are arranged to form four circular ring shells 15. The distance between the shells 15, and thus the gap 16 between the shells, is, according to the embodiment, larger than the distance between the individual circular rings 14.The horizontally arranged annular shells 15, with a height relative to the base body 1, form a horizontal plane. The horizontal planes of the annular shells 15, with the heat exchanger tubes 12 included therein, are arranged at a uniform, predetermined horizontal distance from one another. However, this distance can, in principle, be variable and differ between the horizontal planes, in accordance with the technical invention. In the illustrated embodiment, six horizontal planes are arranged one above the other. The uppermost horizontal plane has a predetermined distance to the top / lid 20 of the base body 1, which, however, can be variably configured. The ice storage heat exchanger is fundamentally designed as a plastic tube extraction / regeneration heat exchanger.

[0054] In the Fig. 5 Figure 11 shows a section of an ice storage heat exchanger construction / support structure 11 according to the invention in a third embodiment, in side view. The figure 11 is shown in Figure 2. Fig. 3 and Fig. 4 In addition to the embodiments shown, a distributor 17 is shown in the front view, through which a supply line 21 of the heat exchanger fluid is provided to the heat exchanger tubes 12, which are designed as plastic tubes and fixed at connection points 22 on the vertical supports 13. The distributor 17 is fixed to the ceiling / cover 20 of the base body 1. However, other embodiments of the fixing are conceivable in principle. The supply line 21 is provided via heat transfer tubes 12, designed as plastic tubes, connected to the distributor 17, which, in the illustrated embodiment, are routed into the lower region of the base body 1. Other configurations of the supply line 21 are conceivable. The configuration shown is referred to as "supply line bottom". Other conceivable configurations include, for example, the configurations "supply line top" or "alternating supply line".The advantages of the "lead-down" and "lead-up" configurations are discussed in connection with the following. Fig. 6 and Fig. 7 The illustrated embodiments are explained.

[0055] In Fig. 6 and Fig. 7 The cooling process from a temperature of approximately ϑ = 11 to a temperature of approximately ϑ = 1 °C for the configurations of the flow 21 "flow below" ( Fig. 6 ) and "lead-up top" ( Fig. 7 ) shown. The results shown are based on cooling experiments in which the behavior of water during a cooling process through the region of its density maximum at a temperature ϑ = 4 °C was investigated. The abscissa of Fig. 6 and Fig. 7 The time τ and the ordinate represent the water temperature ϑ in the base body 1 of the ice storage heat exchanger. The dashed curve (23, 26) corresponds to the mean water temperature in the upper part of base body 1 for the configuration "inlet bottom" and "inlet top," respectively. The dash-dotted curve (24, 27) corresponds to the mean water temperature in the middle part of base body 1 for the configuration "inlet bottom" and "inlet top," respectively. The solid curve (25, 28) corresponds to the mean water temperature in the lower part of base body 1 for the configuration "inlet bottom" and "inlet top," respectively.

[0056] As in Fig. 6 and Fig. 7 As can be seen, a temperature stratification forms in the base body 1 of the ice storage heat exchanger right from the start of the measurements. The warmest water is located in the upper part of base body 1 and the coldest in the lower part. The temperature gradient in base body 1 is, with the "flow at the bottom" configuration ( Fig. 6 ), at approximately Δϑ = 3.7 K and with the "lead-in at the top" configuration ( Fig. 7 ), at approximately Δϑ = 2.9 K. The reason for this smaller temperature gradient is that in the case of the configuration: "flow at the top" ( Fig. 7 The coldest temperature of the heat exchanger fluid flows into the upper part of the base body 1, where the water cools down more rapidly. Within a temperature range of ϑ = 4 °C, the characteristic density inversion / density anomaly of the water occurs. The density of the warm water in the upper part of the base body 1 increases during the cooling process until it reaches its point of highest density at ϑ = 4 °C. The water then stratifies within the base body 1, so that from this point on, the warmest temperature prevails in the lower part of the base body 1. Temperature fluctuations occur in the region of the density inversion / density anomaly, from approximately τ = 25,000 s to τ = 50,000 s. These could be due to internal instabilities in the temperature stratification and the resulting stronger convection in the base body 1. The heat transfer in the ice storage heat exchanger should therefore be higher in this area than with stable temperature stratification in the ice storage.Due to the faster cooling of the water temperature in the base body 1, the following occurs in the "flow at top" configuration (. Fig. 7 ), the density inversion / density anomaly occurs approximately τ = 2,000 s earlier. In general, heat transfer is dominated by natural convection. Below ϑ = 4 °C, a stable temperature stratification re-establishes itself in the base body 1. However, the coldest temperature is now located in the upper part of the base body 1 and the warmest in the lower part of the base body 1. The temperature gradient for the "flow at the bottom" configuration ( Fig.6 ), is in this case marginally smaller than with the "lead-up top" configuration ( Fig. 7 The reason for this is the same as for water temperatures above ϑ = 4°C.

[0057] In the further course of the cooling tests, the two configurations "lower feed" ( Fig. 6 ) and "lead-up top" ( Fig. 7 ) led to icing. It was found that ice formation already occurs at water temperatures in the base body 1 of the ice storage heat exchanger of ϑ > 0 °C. In this case, the ice formation process differs between the "bottom flow" configurations ( Fig. 6 ) and "lead-up top" ( Fig. 7 ). Is the configuration "lead-up top" ( Fig. 6 If the configuration "flow at bottom" is selected, both the coldest water temperature of the base body 1 and the coldest temperature of the heat exchanger fluid are located at the surface of the base body 1. This promotes ice formation in this area, which can then proceed constantly downwards along the heat exchanger tubes 12. However, if the configuration "flow at bottom" ( Fig. 7 If the temperature of the heat exchanger fluid is selected, the coldest temperature is located in the warmest area of ​​the base body 1. Ice growth on the heat exchanger is suppressed by the warmer water surrounding the ice layer. In this case, ice growth proceeds more slowly.

[0058] These measurements suggest that the "lead-down" configuration ( Fig. 6 ) enables optimal extraction performance at all heat exchanger tubes 12 and optimal ice formation. Bezugszeichenliste

[0059] 1 Support structure / Ice storage heat exchanger construction Base body of an ice storage heat exchanger / Base body 2 Aluminum support according to state of the art for ice storage regeneration heat exchangers 3 Center of a heat exchanger ice storage construction 4 Heat exchanger tube / Plastic tube according to state of the art for ice storage regeneration heat exchangers 5 Vertical aluminum support according to state of the art for ice storage extraction heat exchangers 6 Horizontal aluminum supports according to state of the art for ice storage extraction heat exchangers 7 Vertical aluminum supports according to state of the art for ice storage extraction heat exchangers 8 Spiral plastic tube according to state of the art for ice storage extraction heat exchangers 9 Walls / Ice storage periphery 10 Base 11 Ice storage heat exchanger construction / Support structure / Inventive ice storage heat exchanger construction 12 Heat exchanger tube / Plastic tube / Coil / Pipe coil / Pipe loop 13 In the direction of gravityAligned supports / Vertical supports / Supports 14 Circular ring 15 Circular ring shell / Shell / Concentric shell 16 Gap / Gap between circular ring shells 17 Manifold / Lockable manifold / Lockable plastic pipe manifold 18 Circular ring segment 19 Heat pump side pipe 20 Ceiling / Cover 21 Flow / Flow direction 22 Connection point 23 Average water temperature in the upper part of the base for the "flow at bottom" configuration 24 Average water temperature in the middle part of the base for the "flow at bottom" configuration 25 Average water temperature in the lower part of the base for the "flow at bottom" configuration 26 Average water temperature in the upper part of the base for the "flow at top" configuration 27 Average water temperature in the middle part of the base for the "flow at top" configuration 28 Average water temperature in the lower part of the base for the "flow at top" configuration

Claims

1. Ice storage unit with a hollow base body (1) in which heat exchanger tubes (12) are arranged as heat exchangers, in which a heat exchanger fluid is guided to exchange heat with a second heat exchanger fluid stored in the base body (1), wherein a support structure (11) for the heat exchanger tubes (12) is provided, which has supports (13) oriented substantially in the direction of gravity, characterized by the fact that the supports (13) are arranged such that they define concentric shells (15).

2. Ice storage system according to claim 1, characterized by the fact that the heat exchanger tubes (12) are attached to connection points (22) on the supports (13).

3. Ice storage unit according to claims 1 and 2, characterized by the fact that the heat exchanger tubes (12) are only fixed in their position by the vertical supports (13) in the base body (1).

4. Ice storage system according to claims 1 to 3, characterized by the fact thatexactly one heat exchanger tube (12) is arranged in a helical fashion on a horizontal plane on the vertical supports (13), wherein a plurality of helixes formed by several heat exchanger tubes (12) describe an annular shell (15) or each heat exchanger tube (12) leaving a horizontal plane is arranged in a corkscrew-like fashion on the vertical supports (13).

5. Ice storage unit according to claim 4, characterized by the fact that several annular shells (15) are arranged successively in the radial direction.

6. Ice storage system according to claims 4 and 5, characterized by the fact that the shells (15) are arranged at uneven intervals around a common center (3) or at different distances around a common center (3).

7. Ice storage system according to claims 4 to 6, characterized by the fact that after a predefined number of shells (15) there is a greater distance (16) between two shells (15) than between at least two further shells (15).

8. Ice storage unit according to claim 4, characterized by the fact that the curvature of the heat exchanger tubes (12) decreases radially outwards from the center (3) of the ice storage or the supporting structure (11).

9. Ice storage device preferably according to claims 1 to 8, characterized by the fact that a distributor (17) is prepared to switch the supply of the heat exchanger fluid to the heat exchanger tubes (12) depending on the individual horizontal planes / circular rings and to configure the position of the heat exchanger tubes (12) variably.

10. Method for assembling an ice storage system wherein supports (13) of a supporting structure (11) define concentric shells (15), wherein at least two heat exchanger tubes (12) run in different planes and are attached to the supports (13) starting from the supports (13) defining the innermost shell (15).

11. Method for operating the ice storage system according to one of claims 1 to 8, wherein the coldest area at the bottom of one of the inner shells (15) is specifically created in order to effect partial or complete icing from there, or the coldest area in the inner shell (15) is specifically created far from the bottom in order to effect rapid but incomplete icing in the long term.

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