METHOD FOR MAINTAINING THE TEMPERATURE OF FLUID MEDIA

Description

[0001] The present invention relates to a method for maintaining the temperature of fluid media in pipes even when the flow of the fluid media is interrupted, a pipe sheathed with the method, a passive heat retention system for hot water pipes and / or a cold retention system for cold water pipes in residential and office buildings as well as process engineering plants, and the use of the sheathed pipe.

[0002] Residential and office buildings are typically equipped with cold and hot water pipes. While the temperature of the cold water in cold water pipes is usually not regulated, the hot water must be heated sufficiently so that it is perceived as hot water after the hot water tap is opened, even after traveling through the hot water pipes. Since hot water in multi-story buildings is often heated centrally, for example in the basement, and distributed from there throughout the building, the hot water pipes must be well insulated to reduce heat loss during transport.

[0003] In buildings, hot water is typically only needed for a few minutes at most per use. Afterwards, the water in the hot water pipe cools down again despite thermal insulation. Therefore, when a hot water tap is turned on, it often takes some time for the water to become hot. To prevent this, some building codes require that hot water pipes be kept warm, for example, by means of a circulation system or pipe heating.

[0004] In a circulation system, a circulation pump continuously pumps reheated hot water in a pipe parallel to the hot water pipe – for example, in a double-walled pipe or a return pipe – in order to keep the water temperature of the hot water pipe at the desired temperature, even if the flow of the medium is interrupted for some time.

[0005] Pipe tracing involves wrapping or running an electrical resistance, such as a cable or heating tape, around or along the pipe. Applying an electrical voltage heats the cable or heating tape, thus electrically heating the pipe. Temperature sensors can also be incorporated.

[0006] Circulation systems, particularly those with double-sheathed or return lines, and electric pipe tracing are so-called active heat retention systems. These are technically complex to manufacture and very energy-intensive and therefore costly to operate, even when no hot water is used. They also have the disadvantage that if the pipework malfunctions (cable breakage, for example, due to thermal expansion of the pipe, aging of the cable insulation, etc.), structural damage can occur and the system's function can be interrupted along the entire length of the pipe. Furthermore, there is a risk that if the electric pipe tracing breaks, the electrical voltage could cause smoldering fires and / or, for example, endanger people or cause other damage via the metallic pipework, even at remote locations.These systems – and electric trace heating in particular – consume a great deal of electrical energy, which is also significantly more valuable than heat energy. Therefore, not least for environmental reasons, they should be avoided whenever possible.

[0007] For hygienic reasons, cold water pipes should be kept below 25°C, as temperatures above 25°C lead to the proliferation of human pathogenic germs, particularly Legionella. However, in residential and office buildings, cold water pipes are generally not cooled nowadays due to a lack of simple, suitable solutions; instead, the low temperature of the water at the point where it enters the building is relied upon.

[0008] The object of the present invention is therefore to provide a passive hot water retention system and a passive cold water retention system for cold water pipes in residential and office buildings. The passive hot water retention system should ensure that the water temperature in hot water pipes remains warm for hours after water has been drawn, without any external energy input. The passive cold water retention system should prevent the water temperature of cold water from remaining cold, i.e., not rising above 25°C, even at warm outside temperatures and for hours after water has been drawn. This should prevent the growth of Legionella bacteria in the hot / cold water pipes. Furthermore, the passive hot / cold water retention system should be easy to cut to size on-site and simple to attach to the hot or cold water pipe. It should also be possible to easily insulate the hot water retention system.

[0009] The problem was surprisingly solved with a method according to claim 1 for maintaining the temperature of fluid media in pipes even when the flow of the fluid media is interrupted, wherein the pipes are suitable for building services engineering, structural engineering, and chemical and process engineering plants, wherein a) in a first step a heat storage layer (1) is produced comprising at least one latent heat storage material (2) and at least one matrix material (3), wherein, if the latent heat storage material (2) is in microencapsulated form in the matrix material (3), the matrix material (3) is not a thermal insulation material (5), and b) in a second step the heat storage layer (1) is arranged around a pipe (4) and subsequently the pipe (4) covered with the heat storage layer (1) is encased with thermal insulation material (5) in the form of a pipe shell, thus obtaining an encased pipe (41), wherein the thermal insulation material (5) has a thermal conductivity of ≤ 0.1 W / ((m·K).

[0010] Furthermore, a sheathed tube (41) is also claimed to be obtained according to the inventive method.

[0011] A passive warming system for hot water pipes and / or a colding system for cold water pipes in residential and office buildings as well as for chemical and process engineering plants, comprising at least one sheathed pipe (41) according to the invention, is also claimed. The use of the sheathed pipe (41) according to the invention for keeping fluid media warm, in particular as hot water pipes in buildings, steam pipes, pipes for transporting chemicals, bitumen, silicones, hot melt adhesives, and / or foodstuffs such as chocolate, and / or for keeping fluid media cold, in particular fluid media under pressure, gases and / or liquids, in particular cooling liquids, chemicals, solvents with high vapor pressure, and / or foodstuffs such as dairy products and beverages, is also claimed.

[0012] The inventive method, the inventive sheathed pipe (41), the passive heat retention system for hot water pipes and / or cold retention system for cold water pipes – hereinafter referred to as the hot / cold retention system for hot / cold water pipes – in residential and office buildings as well as in process plants, and the inventive uses surprisingly offer many advantages. For example, a permanently effective passive temperature retention system for temperatures higher or lower than the ambient temperature, i.e., a heat retention system or a cold retention system, can be provided in a simple manner. This system can be used not only for hot and / or cold water pipes in residential and office buildings, but – depending on the selected phase transition temperature of the latent heat storage material (2) – also for higher temperatures of the fluid medium, such as 125°C for steam pipes.If the fluid medium is no longer being pumped, causing its temperature to drop despite the thermal insulation, the latent heat storage material (2) releases enthalpy of fusion to the surroundings and to the medium in the pipe (4) during the phase transition from liquid to solid. With optimal thermal conductivity of the pipe wall, this maintains the temperature of the medium in the pipe at its melting point, and it only drops when essentially all of the latent heat storage material (2) has frozen, i.e., when the phase transition from liquid to solid is complete. This allows the temperature of the fluid medium to be passively maintained, i.e., without additional energy input or output, for extended periods – for example, over several hours – essentially at the phase change temperature of the latent heat storage material (2), even during a flow interruption.Consequently, the inventive hot / cold water maintenance system for hot / cold water pipes, particularly in residential and office buildings as well as in process plants, surprisingly eliminates the need for energy-intensive circulation systems and pipe tracing. Furthermore, retrofitting existing hot / cold water pipes with the inventive passive hot / cold water maintenance system is always simple, especially when the hot / cold water pipes are located in a pipe shaft – for example, one that is accessible. The passive cold water maintenance system also allows for the easy keeping of water cold in cold water pipes, which is generally not practiced for energy efficiency reasons. The lower temperature significantly slows the proliferation of potential pathogens in cold water pipes.Consequently, water drawn from such pipes has a lower proportion of germs, which is a positive health aspect.

[0013] Surprisingly, the inventive method, the inventive sheathed pipe (41), the passive hot / cold retention system for hot / cold water pipes, and the inventive uses, with a suitable selection of the latent heat storage material (2), can be used to maintain the temperature of both heated fluid media, such as steam pipes or hot water pipes in buildings, and cold fluid media, such as in refrigeration systems. Furthermore, the inventive sheathed pipe (41), and thus the passive hot / cold retention system for hot / cold water pipes, can surprisingly be easily cut to size both at the factory and on-site using tools commonly available on site.

[0014] Thus, thanks to the present invention, temperatures of fluid media in pipes can surprisingly and in a simple, low-energy manner be maintained over an extremely wide selectable temperature range for hours or even days without the input or output of energy, i.e. passively and therefore also without recirculation, without a double jacket and without electrical trace heating or electrically operated Peltier elements, essentially at the phase change temperature of the latent heat storage material (2) used, even if the fluid medium no longer flows - or not continuously.

[0015] The inventive method and the inventively sheathed pipe (41) can thus be used in a surprisingly versatile manner according to the inventive uses, such as in hot water pipes in buildings, and in heating and cooling systems. It also provides simple, energy-efficient temperature protection, for example, in the event of malfunctions in chemical plants and / or pumps of temperature-sensitive fluid media. Furthermore, the inventively sheathed pipe (41) can be easily cut to the required length – typically on-site – without any latent heat storage material (2) escaping from it, even at temperatures above the melting point of the latent heat storage material (2).

[0016] The heat storage layer (1) can be easily cut to size if necessary, even without any latent heat storage material (2) escaping from the heat storage layer (1) – either alone or in combination with the thermal insulation material (5), and thus forming an unstressed heat storage-insulation composite (51). In other words, the heat storage layer (1) and the heat storage-insulation composite (51) do not bleed, or at most only minimally, even when cut to size.

[0017] Surprisingly, the inventive passive hot / cold water maintenance system for hot water pipes and / or the inventive passive cold water maintenance system for cold water pipes in residential and office buildings, as well as in chemical and process engineering plants, allows the hot or cold water temperature to be maintained for many hours or even days without the need for active energy input. This enables a significant reduction in energy consumption in residential and office buildings, as well as in chemical and process engineering plants. Furthermore, the simple and maintenance-free operation of the passive hot / cold water maintenance system for hot / cold water pipes also allows for installation in houses and buildings where no such system has previously been installed. This significantly reduces water consumption.

[0018] Pipelines, especially deep-sea pipelines for transporting crude oil, which are surrounded by a phase-change material, are frequently described in the literature. The phase-change material serves to extend the cooling time and to prevent the solidification of the medium flowing in the pipeline, particularly the crude oil.

[0019] US Patent 6,000,438 describes a deep-sea pipeline with passive insulation featuring improved transient heat loss properties. The pipeline is equipped with thermal insulation incorporating a dispersed or microencapsulated phase-change material. This is intended to significantly extend the cooling time of the produced or conveyed hydrocarbon liquid in the event of a production interruption. A disadvantage of thermal insulation containing dispersed or microencapsulated phase-change material is its reduced thermal insulation function. Furthermore, only the portion of the phase-change material located near the conveyed hydrocarbon, i.e., close to the pipeline, contributes to the extended cooling time. The majority of the phase-change material within the thermal insulation is below its phase-change temperature and therefore cannot extend the cooling time.However, due to an increased thermal conductivity caused by the presence of the thermally conductive phase change material, the thermal insulation is reduced (. Figs. 1 and 2 ).

[0020] WO-A-2011 / 161472 describes a passive thermal management system for underwater pipelines used to transport liquids such as crude oil away from an underwater wellhead. During extraction, the crude oil has a temperature of approximately 50°C to 90°C, while the ambient seawater temperature is around 0°C. However, if the crude oil temperature drops below approximately 25°C, it can solidify and clog the pipeline. Therefore, the passive thermal management system incorporates a phase-change material with a melting point selected such that, if the crude oil transport is interrupted, heat is transferred from the phase-change layer to the cooling crude oil, thus keeping it in a liquid state for a longer period.

[0021] WO-A-2012 / 175994 relates to a device and a method for maintaining the temperature, in particular of crude oil, in an underwater pipeline. It uses a material with high latent heat of phase change to transfer latent heat to the fluid when the fluid temperature decreases towards a threshold value. The material may be encased in an insulating tape. A matrix comprising a matrix material, a phase change material, and a thermal insulation material is not mentioned.

[0022] WO-A-02 / 062918 describes a process for producing a quasi-incompressible phase-change material with shear-thinning properties and low thermal conductivity. The phase-change material, consisting of a mixture of selected chemical compounds in the liquid phase, is mixed with a bulky polymer as a texturizing agent. The texturizing agent gives the phase-change material a gel-like consistency without shear stress; however, it liquefies again under shear stress. The gelled phase-change material is used for thermal insulation of pipelines such as hydrocarbon transport pipelines, particularly deep-sea crude oil pipelines. The process does not mention the encasing of such pipelines, coated with the gelled phase-change material, with thermal insulation material.

[0023] EP-A-2 712 893 describes a process for manufacturing pipelines, particularly offshore pipelines, with heat-storing properties. In this process, an organic polyisocyanate is mixed with at least one polymeric compound having at least two hydrogen atoms reactive towards isocyanate, a catalyst, wax, and optionally other additives to form a reaction mixture. This mixture is then applied to a pipe and reacted to form a polyurethane layer. Thermal insulation materials, especially those enclosing the pipeline with the reacted reaction mixture, are not mentioned.

[0024] WO-A-02 / 16733 describes a temperature control device to prevent the formation of alkane hydrates in underwater oil and gas production, particularly at a subsea eruption cross (also known as a Subsea Christmas Tree). The device comprises a housing and a phase-change material located within the housing. The phase-change material has a phase transition temperature higher than the temperature at which alkane hydrates form. The phase-change material is used as is, without being embedded in a matrix or encapsulated. Furthermore, thermal insulation materials are not mentioned.

[0025] These devices and methods for crude oil pipelines, particularly for deep-sea crude oil production, are not suitable for residential and office buildings or for above-ground pipelines. Deep-sea pipelines and the equipment used for them must, among other things, withstand high water pressure and be highly resistant to external mechanical damage. Crude oil pipelines also have a complex structure and significantly larger dimensions than water pipes in residential and office buildings. Furthermore, thermal insulation materials such as those used according to the invention are not suitable for deep-sea applications because they would be destroyed or at least severely compressed by the forces acting upon them, thereby destroying their thermal insulation properties. The procedure

[0026] The inventive method serves to maintain, i.e., stabilize, the temperature of fluid media in pipes even when the flow of the fluid media through the pipes is interrupted. The pipes are suitable for building services engineering, structural engineering – and thus for residential and office buildings – as well as for chemical and process engineering plants, and are therefore preferably part of building services engineering, structural engineering, and chemical and process engineering plants. Thus, the method relates to above-ground pipes, in particular those of residential and office buildings as well as chemical and process engineering plants.

[0027] The inventive method and the sheathed pipe (41) are not suitable for apparatus and pipelines of the petroleum and natural gas industry and therefore not for the extraction of crude oil, in particular not for deep sea crude oil extraction.

[0028] The term fluid media, also called fluid or simply medium, encompasses, according to the invention, any media that are flowable and thus transportable at the temperature prevailing in the pipe at the time of transport. Non-limiting examples of such fluid media include, in particular, gases, liquids, suspensions, slurries, dispersions, emulsions, and / or mixtures thereof. However, crude oil is not a preferred fluid medium for the purposes of the invention.

[0029] In a first step a) of the inventive method, a heat storage layer (1) is produced, wherein the heat storage layer (1) comprises at least one latent heat storage material (2) and at least one matrix material (3), wherein, if the latent heat storage material (2) is in microencapsulated form, the matrix material (3) is not a thermal insulation material (5).

[0030] In the embodiment of the second step b) of the inventive method, the heat storage layer (1) is arranged around the pipe (4), for example in the form of a band, and optionally fastened. The heat storage layer (1) can completely or only partially cover the pipe (4). The heat storage layer (1) can be fastened spirally around the pipe (4) and / or – for example in the form of an elongated rectangle – around the pipe (4). Fig. 4The width of the rectangle can be chosen, for example, to correspond to the circumference of the pipe (4) and thus, when placed around the pipe (4), completely enclose it. It is also possible to choose a width of the rectangle smaller than the pipe circumference, so that part of the pipe is not covered by the heat storage layer (1), and / or to place two or more rectangles of the heat storage layer (1) parallel to each other on the pipe surface. Furthermore, it is also possible to place two or more heat storage layers (1) with the same or different composition on top of each other. Subsequently, the pipe (4) covered with the heat storage layer (1) is encased with thermal insulation material (5), in particular with thermal insulation material (5) having a suitable profile, i.e., a recess, that optimally surrounds the pipe (4) with the heat storage layer (1), thereby obtaining an encased pipe (41).

[0031] In an unclaimed embodiment of the method, the heat storage layer (1) is first brought into contact with the thermal insulation material (5), thereby obtaining a heat storage-insulation composite (51), with which the pipe (4) is then encased such that the heat storage layer (1) of the heat storage-insulation composite (51) is located between the pipe (4) and the thermal insulation material (5) of the heat storage-insulation composite (51). The heat storage layer (1) can comprise all or only part of the inner layer of the thermal insulation material (5). Fig. 3It is also possible to equip only a part, for example only half, of a multi-part pipe shell with a heat storage layer (1). The thermal insulation material (5) is preferably provided with a profile, i.e., a recess, in which the heat storage layer (1) is arranged. The profile of the thermal insulation material (5) is typically selected such that it optimally encompasses the pipe (4) and the heat storage layer (1).

[0032] The latent heat storage material (2) of the heat storage layer (1) is advantageously selected such that the melting point, i.e., the solid / liquid phase change or phase transition temperature, of the latent heat storage material (2) differs somewhat, i.e., typically by 1°C to 5°C, from the temperature of the fluid medium contained in the pipe and being conveyed. If the medium temperature—typically in the case of warm fluid media—is higher than the ambient temperature, the melting point is advantageously lower than the temperature of the conveyed medium. And if the medium temperature—typically in the case of cooled fluid media—is lower than the ambient temperature, the melting point of the latent heat storage material (2) is advantageously higher than the temperature of the conveyed medium.

[0033] For example, in larger buildings, the target water temperature for hot water pipes is 55°C. If the hot water flow is stopped, the hot water cools down only with thermal insulation and without a heat retention system. If a latent heat storage material (2) with a melting point of 50 to 54°C – for example, diphenylamine with a melting point of 52.9°C or paraffin with 24 carbon atoms at 50.6°C – is used, the entire latent heat storage material (2) present in the heat storage layer (1) has a temperature above its melting point. Accordingly, the latent heat storage material (2) is in a molten, i.e., liquid, state. If the hot water flow is now interrupted, the hot water cools down somewhat.However, as soon as the temperature of the hot water approaches the melting point of the latent heat storage material (2), a portion of the latent heat storage material (2) solidifies, releasing enthalpy of fusion. This enthalpy is then transferred to the surroundings and to the hot water. This prevents further cooling and stabilizes the temperature of the hot water at the melting point of the latent heat storage material (2). This process continues until all of the latent heat storage material (2) has solidified. Therefore, the duration for which the hot water is maintained at the desired temperature can be determined by selecting the thickness of the heat storage layer (1), the type and quantity of latent heat storage material (2) within the heat storage layer (1), and the type and thickness of the thermal insulation material (5).During the next hot water draw-off, the flowing hot water heats the solidified latent heat storage material (2), causing it to melt again and thus be activated for the next cycle.

[0034] In a refrigeration system where a cooled fluid medium flows through the pipe (4), the ambient temperature is higher than the temperature of the fluid medium. If the latter has a temperature of, for example, -23°C, a latent heat storage material (2) with a melting point of -16°C to -21°C can be used. Non-limiting examples are ethylene glycol with a melting point of -16°C or an aqueous calcium chloride, CaCl₂, solution of -21.3°C. Thus, in this arrangement, all latent heat storage material (2) is in solidified form. If the flow of the refrigeration system's fluid medium is now stopped, the cooled medium warms up to the melting point of the latent heat storage material (2). If heat then penetrates from the outside towards the pipe (4) via the thermal insulation, the latent heat storage material (2) is melted first.During this process, the cooled fluid medium remains at a constant temperature until all the latent heat storage material (2) has melted. By appropriately selecting the thickness of the heat storage layer (1), the type and quantity of the latent heat storage material (2) in the heat storage layer (1), and the type and thickness of the thermal insulation material (5), the duration for which the cooled fluid medium is to be maintained at the desired temperature can be determined. When the interruption is resolved, the flowing cold fluid medium cools the molten latent heat storage material (2), causing it to solidify and thus be reactivated for the next interruption.

[0035] When transporting fluids at their boiling point and at temperatures below ambient temperature, an interruption of the fluid transport leads to evaporation of the liquid, resulting in a rapid pressure increase and potentially dangerous conditions. The inventive method, the inventively sheathed pipe (41), the unclaimed heat storage insulation composite (51), and the passive hot / cold keeping system for hot / cold water pipes prevent this effect for a longer period, during which the fault can usually be rectified. This prevents the activation of safety valves or rupture discs in most cases. This is particularly important for modern refrigeration systems using natural refrigerants such as pentane, butane, propane, ammonia, and / or CO₂, as these fluids operate at temperatures close to their boiling points.

[0036] Thermal networks in the low-temperature range are also increasingly operated with CO2, in which significantly more efficient and energy-efficient pipe insulation can be installed between the heat source and the sink using the present invention.

[0037] Based on known, publicly available data and, where appropriate, on the basis of his or her expertise, the expert can determine suitable latent heat storage materials (2), their proportion in the heat storage layer (1), the necessary thickness of the heat storage layer (1) and the type and thickness of the optimal thermal insulation material (5). The heat storage layer (1)

[0038] The heat storage layer (1) preferably exists in the form of a planar layer with a typically uniform thickness. At temperatures above the melting point of the latent heat storage material (2), the heat storage layer (1) is typically flexible and thus bendable and malleable.

[0039] The thickness of the heat storage layer (1) can be chosen essentially arbitrarily and adapted to the specific requirements. In In many cases, however, a layer thickness of the heat storage layer (1) of approximately 0.1 to 20 cm, preferably of approximately 0.15 to 10 cm, in particular of approximately 0.2 to 5 cm, measured with a caliper according to DIN 862, in particular with a caliper according to DIN 862 with vernier form A1, is sufficient.

[0040] The heat storage layer (1) of the inventive method and of the unclaimed heat storage insulation composite (51) comprises at least one latent heat storage material (2) and at least one matrix material (3), wherein, if the latent heat storage material (2) is in microencapsulated form, the matrix material (3) is not a thermal insulation material (5).

[0041] The latent heat storage material (2) is embedded in the matrix material (3). Thus, the matrix material (3) ensures that the latent heat storage material (2) remains in place even in its liquid state and does not flow away. This also prevents the latent heat storage material (2) from reaching the surface of the heat storage layer (1) as a liquid, meaning that the bleeding, also known as sweating, of the heat storage layer (1) is significantly reduced or even completely prevented.

[0042] In a preferred embodiment, the amount of latent heat storage material (2) in the heat storage layer (1) is selected such that the solid / liquid heat capacity (including the phase change enthalpy) of the heat storage layer (1) within a temperature range of 10 K is at least 50 kJ, preferably at least 80 kJ, and particularly at least 120 kJ, per kg of heat storage layer (1), as measured by DSC according to EN ISO 11357-1 and -4. It is known to those skilled in the art how to determine this amount without inventive step. The amount of latent heat storage material (2) depends in particular on the desired melting temperature of the heat storage layer (1), the selected latent heat storage material (2), and the heat capacity of the fluid medium. The matrix material (3) used generally contributes little to the heat capacity of the heat storage layer (1).

[0043] In another preferred embodiment, the heat storage layer (1) consists essentially of 30 to 95 wt.%, preferably 40 to 90 wt.%, in particular 50 to 85 wt.%, latent heat storage material (2), 5 to 70 wt.%, preferably 10 to 60 wt.%, in particular 15 to 50 wt.%, matrix material (3), and 0 to 20 wt.%, preferably 0 to 15 wt.%, in particular 0 to 10 wt.%, further components.

[0044] A preferred further component of the heat storage layer (1) comprises at least one nucleation additive in an advantageous amount of 0.1 to 10 wt.%, preferably 0.2 to 6 wt.%, and in particular 0.3 to 5 wt.%, based on the total amount of the latent heat storage material (2) used. Suitable nucleation additives are known to those skilled in the art. Non-limiting examples include silicon dioxide, silica, nanoparticles, metal oxide particles of iron, copper and / or aluminum, and / or carbon nanotubes. The layer (11)

[0045] According to the invention, at least one side of the heat storage layer (1) – either completely or only a portion of the surface – is covered by a layer (11), wherein the layer (11) preferably comprises a paper layer, a plastic film, in particular a polyethylene, PE, polypropylene, PP, polystyrene, PS, polyethylene terephthalate, PET and / or plastic laminate film, a metal film, in particular an aluminum, copper, tin, zinc and / or steel film, a metal-plastic layer, and / or a laminate. The layer (11) may also be reinforced by fibers, in particular glass fibers, carbon fibers and / or plastic fibers.

[0046] If the side of the heat storage layer (1) facing the fluid medium comprises a layer (11), this layer is preferably a thermally conductive layer (11). If the side of the heat storage layer (1) facing away from the fluid medium comprises a layer (11), this layer is preferably a non-thermally conductive layer (11). A thermally conductive layer (11) is understood to have a thermal conductivity of ≥ 10 W / (m K). Preferred, non-limiting examples of suitable thermally conductive layers (11) are metal foils such as aluminum foil, copper foil, tin, zinc, and / or steel foil. Preferred, non-limiting examples of suitable non-thermally conductive layers (11) are plastic films such as PE films, PP films, and / or PET films.

[0047] Advantageously, the layer (11) has a layer thickness of 0.001 mm to 2 cm, preferably 0.002 mm to 1 cm, and in particular 0.003 mm to 0.5 cm, measured with a caliper according to DIN 862, in particular with a caliper according to DIN 862 with vernier form A1. If layer thickness measurement with a caliper is not possible due to insufficient layer thickness, i.e., if the standard deviation of the mean of 5 measurements is more than 30% of the mean, the layer thickness is determined with an ultrasonic thickness gauge. The composites (13, 14, 15, 16)

[0048] In a particularly preferred embodiment, the heat storage layer (1) essentially, i.e. in particular to at least 80 wt.%, is a composite, in particular a composite (13, 14, 15, 16).

[0049] In a preferred embodiment i), the heat storage layer (1) essentially comprises a composite (13), wherein the composite (13) is obtained by heating, mixing, and cooling at least one latent heat storage material (2), at least one matrix material (3), and optionally at least one nucleation additive. Such composites (13) are known to those skilled in the art and are described in the literature, for example, in WO-A-2009 / 118344. They can be produced, for example, by extrusion, then optionally granulated, and further processed, for example, into a planar heat storage layer (1) or into fibers. The fibers can, for example, be used to produce nonwovens and / or woven fabrics and, in this form, incorporated as a composite (13) in the heat storage layer (1).

[0050] In a preferred embodiment ii), the heat storage layer (1) essentially comprises a composite (14), wherein the composite (14) includes the latent heat storage material (2) which is sorbed, i.e., adsorbed and / or absorbed, onto the matrix material (3). The matrix material (3) preferably comprises a nonwoven fabric, a woven fabric, and / or a sheet-like porous material, wherein the nonwoven fabric and / or woven fabric may optionally comprise fibers made from the composite (13). The nonwoven fabric and / or woven fabric may also comprise hollow fibers in which the latent heat storage material (2) is arranged, i.e., for example, filled, adsorbed, and / or absorbed. Suitable nonwoven fabrics, woven fabrics, and sheet-like porous materials are known to those skilled in the art. A non-limiting example of a sheet-like porous material is a thin porous metal layer, for example, sintered metal.

[0051] In a preferred embodiment iii), the heat storage layer (1) essentially comprises a composite (15), wherein the composite (15) comprises a powder and / or granules (151) bonded to at least one matrix material (3), in particular an adhesive, and optionally also to at least one layer (11). The powder and / or granules (151) preferably constitute a microencapsulated latent heat storage material (2) and / or the latent heat storage material (2) is sorbed, i.e., adsorbed and / or absorbed, onto a porous powder- and / or granular carrier material. For the purposes of the invention, the carrier material and the capsule material are considered to be the matrix material (3).

[0052] The production of microencapsulated latent heat storage materials (2) is known and commercially available.

[0053] Suitable porous, powder- and / or granular carrier materials for producing the powder and / or granules (151) of the composite (15) are known to those skilled in the art. The adsorption and absorption of latent heat storage materials (2) onto the powder and / or granules (151) is also known. This preferably takes place at temperatures above the melting point of the respective latent heat storage material (2). The powder and / or granules (151), together with the latent heat storage material (2) contained therein, can also be coated, for example, with a polymer film to further prevent the latent heat storage material (2) from desorbing in the liquid state.

[0054] A suitable and particularly preferred matrix material (3) for bonding the powders and / or granules (151) of the composite (15) together is an adhesive with which the powders and / or granules (151) are held together, i.e., fixed. For example, the powders and / or granules (151) can be applied to a layer (11) and then bonded with the adhesive. Optionally, another layer (11) can be applied over this with the adhesive. The adhesive can be a one-, two-, or multi-component adhesive and thus optionally a reactive adhesive. Suitable adhesives are known to those skilled in the art.

[0055] In a preferred embodiment iv), the heat storage layer (1) essentially comprises a composite (16), wherein the composite (16) comprises the latent heat storage material (2) and a thickener, and wherein the composite (16) is typically in the form of a highly viscous liquid, gel, powder, granules, flakes, and / or paste. Particularly suitable latent heat storage materials (2) of the composite (16) include water and aqueous mixtures and / or aqueous solutions.

[0056] Some of the thickeners can additionally act as nucleation agents for the latent heat storage material (2). SiO₂ is an example of this.

[0057] Suitable thickeners are those that are tailored to the respective latent heat storage material (2) and include organic and inorganic thickeners. A person skilled in the art is familiar with suitable thickeners and can also select one that is optimally tailored to the respective latent heat storage material (2).

[0058] In another particularly preferred embodiment (v), the heat storage layer (1) essentially comprises, i.e., in particular, at least 80 wt.% of the heat storage layer (1), a plurality, i.e., two or more, of chambers made of matrix material (3), wherein the chambers contain latent heat storage material (2), i.e., the chambers are preferably filled with the latent heat storage material (2). The latent heat storage material (2) is preferably in pure form, as a powder and / or granules (151), as a composite (13, 14, 15, 16), and / or as mixtures of two or more composites (13, 14, 15, 16). The chambers can, for example, be open on one side so that they can be easily filled, and the chambers can be covered by a subsequently applied layer (11). The latent heat storage material (2)

[0059] The latent heat storage material (2) of the heat storage layer (1) stores the phase transition enthalpy or releases it to the fluid medium. Thus, the latent heat storage materials (2) utilize the phase change from solid to liquid to absorb heat or the phase change from liquid to solid to release heat. The term phase transition enthalpy, also called phase change enthalpy, refers to the enthalpy of fusion or solidification of the phase transition between solid and liquid or liquid and solid, respectively.

[0060] According to the invention, a phase change is understood to be the change of the state of matter from solid to liquid, i.e., melting, or from liquid to solid, i.e., solidification or freezing. According to the invention, melting, solidification, and freezing are used synonymously. All phase changes generally exhibit the same enthalpy, whereby the absolute value, i.e., the magnitude, of the enthalpy value is relevant. These terms are also used synonymously.

[0061] The term phase change temperature refers to the melting temperature for the phase transition from solid to liquid and the freezing temperature for the phase transition from liquid to solid. These temperatures generally have the same value and are used synonymously. If the latent heat storage material (2) has a phase change temperature range, the phase change temperature is understood to be the arithmetically averaged temperature of the temperature range. If this cannot be clearly determined, the phase change temperature is understood to be the temperature at which the enthalpy uptake of a DSC measurement reaches its maximum. For the purposes of the invention, the melting temperature range is thus understood to be the melting temperature and the freezing temperature range to be the freezing temperature.

[0062] According to the invention, latent heat storage materials (2), also called phase change materials or PCMs, are materials that exhibit a solid-liquid phase change enthalpy of at least 120 kJ / kg of latent heat storage material (2) within a phase change temperature range of 5 K. Phase change enthalpies of suitable substances are known to those skilled in the art from the literature. If corresponding enthalpy values ​​are unavailable, the phase change enthalpy can be measured using DSC according to EN ISO 11357-1 and -4.

[0063] In a preferred embodiment, the latent heat storage material (2) has a melting point between -182°C and +175°C, preferably between -80°C and +150°C, and particularly between -25°C and +125°C. For example, methane, with a melting point of -182°C, can be used as the latent heat storage material (2) to cool oxygen, which has a boiling point of -182°C at normal pressure, and to protect it from evaporation in the event of a cooling system failure. This is because if the oxygen is at a slightly higher pressure, its boiling point also increases accordingly, for example to -180°C. When methane is used as the latent heat storage material (2), it is advantageous if the methane is adsorbed onto a support material at room temperature and optionally encapsulated to prevent evaporation. A pipe (4) can also include a steam line in which steam is conveyed at, for example, a temperature of 125°C.For this purpose, a latent heat storage material (2) is advantageously used which has a phase change temperature of around 120°C to 123°C. A non-limiting example of a suitable latent heat storage material (2) is benzoic acid with a melting point of 121.7°C.

[0064] In another preferred embodiment, the latent heat storage material (2) comprises at least one organic compound, in particular a hydrocarbon, paraffin, alcohol, glycol, polyol, sugar, ketone, ester, ether, carboxylic acid, fatty acid, amide, a sulfur, phosphorus and / or nitrogen compound, and / or an inorganic compound, in particular an inorganic salt, salt hydrate, water and / or an aqueous mixture. Suitable latent heat storage materials (2) are known to those skilled in the art and are described extensively in the literature, for example in the VDI Heat Atlas, 10th edition, Springer Verlag.

[0065] Preferred, non-limiting examples include C14 to C34 paraffins with melting points between 5.5 and 75.9°C and a fusion enthalpy of about 200 to 269 kJ / kg, such as hexadecane with a melting point of 18.3°C and a fusion enthalpy of 210 kJ / kg, ethylene glycol, which has a melting point of -12.9°C and a fusion enthalpy of 160 kJ / kg, water with a melting point of 0°C and a fusion enthalpy of 333.6 kJ / kg, aqueous mixtures such as a glycol-water mixture, which, at an optimal mixing ratio of approximately 70 wt% glycol and 30 wt% water, can be used to obtain a freezing point of -56°C and a fusion enthalpy of 212 kJ / kg, or water-salt mixtures, wherein the salt may be sodium chloride, calcium chloride and / or potassium chloride. Metal salts such as sodium silicate pentahydrate, Na₂SiO₃ · 5H₂O with a melting point of 72.2°C and a fusion enthalpy of 267 kJ / kg, myristic acid with a melting point of 54°C and a fusion enthalpy of 199 kJ / kg. The Matrix material (3)

[0066] The matrix material (3) of the heat storage layer (1) forms a matrix, i.e., a structure that prevents the latent heat storage material (2) from flowing away in liquid, i.e., molten, form – and optionally also in powder and / or granular form. Therefore, it is generally advantageous if the matrix material (3) is in a substantially solid form at room temperature and typically also up to at least 10°C, preferably up to at least 25°C, and particularly up to at least 50°C, above the phase transition temperature of the latent heat storage material (2) incorporated therein.

[0067] InIn a preferred embodiment, the matrix material (3) is a synthetic and / or natural polymer, in particular a polymer based on olefinic monomers such as acrylates, styrene and / or olefins such as polymethyl acrylate, styrene (co)polymers, polyethylene and / or polypropylene, a block copolymer such as block copolymers comprising styrene and / or ethylene, a condensation polymer, in particular polyester, polyamide and / or polyethylene terephthalate, a biopolymer, in particular a protein, a polysaccharide, and / or a natural fiber, a carrier material, a thickener and / or an adhesive. Accordingly, the matrix material (3) is a fully reacted polymer at the time it is mixed with the latent heat storage material (2) and is therefore typically chemically inert to the exposed environment.

[0068] According to the particularly preferred embodiments i), ii), iii) iv) and v) and the composites (13, 14, 15, 16) a matrix material (3) or a plurality of different matrix materials (3) can be used.

[0069] Preferred matrix materials (3) for embodiments i) and ii) include acrylates and methacrylates such as polymethyl methacrylate, PMMA, polyethylene, LDPE, HDPE, polypropylene, polyethylene terephthalate, polystyrene, block polymers such as styrene-butadiene block copolymer, styrene-polybutadiene block copolymer, styrene-isoprene block copolymer, styrene-polyisoprene block copolymer, styrene-ethene-butene-styrene block copolymer (SEBS), styrene-[ethylene-(ethylene-propylene)]-styrene block copolymer (SEEPS), polyamides, polyesters, cellulose, silicates, glass fibers, fabrics such as glass fabrics and / or nonwovens.

[0070] Preferred matrix materials (3) for embodiments iii) include carrier materials and adhesives. Non-limiting examples of suitable carrier materials include expanded clay, expanded glass, Aerosil, silica, expanded vermiculite, amorphous silicon dioxide, pumice, expanded shale, perlite, fly ash, and / or organic powders and / or granules such as porous polysaccharides like starch ethers and / or cellulose fibers. Non-limiting examples of suitable adhesives include organic adhesives such as water-based adhesives, for example, dispersion adhesives based on vinyl acetate or ethylene-vinyl acetate, polyacrylate adhesives, polyurethane adhesives, epoxy-hardener adhesives, hot melt adhesives, in particular reactive hot melt adhesives, and / or inorganic adhesives such as water glass, gypsum, and / or cement.

[0071] It is noted that porous materials can be used both as thermal insulation material (5) and as a carrier material, for example, for the production of a composite (15) of embodiment iii) or as a thickener for the production of a composite (15) of embodiment iv). These materials, such as expanded clay, Aerosil, and / or amorphous silicon dioxide, are suitable as thermal insulation materials (5) provided their pores are filled with gas, in particular air. However, if a liquid or a solid fills these pores, they lose their thermal insulation properties. Nevertheless, they then function as a carrier material or as a thickener.

[0072] Preferred matrix materials (3) for embodiment iv) include organic and inorganic thickeners. Non-limiting examples of suitable thickeners—particularly for water and aqueous systems—include acrylate thickeners, cross-linked polyacrylic acids, associative thickeners, polysaccharide thickeners such as starch ethers, cellulose ethers, guar ether, carrageenan, locust bean gum, pectins, xanthan gum, polyvinyl alcohol, polyvinyl acetate, silicates, silicon dioxide, SiO₂, aerogels, silica gels, aerosils, bentonite, hectorite, and / or carbon nanotubes. For organic latent heat storage materials (2), hydrophobically modified thickeners such as hydrophobic organic polymers and / or hydrophobic SiO₂ may also be used.

[0073] Suitable matrix materials (3) for the chambers of embodiment v) include polymethyl methacrylate, PMMA, polyethylene, LDPE, HDPE, polypropylene, polyethylene terephthalate, polystyrene, block polymers such as styrene-butadiene block copolymer, styrene-polybutadiene block copolymer, styrene-isoprene block copolymer, styrene-polyisoprene block copolymer, styrene-ethene-butene-styrene block copolymer (SEBS) and / or styrene-[ethylene-(ethylene-propylene)]-styrene block copolymer (SEEPS). The pipe (4)

[0074] The pipe (4) of the inventive method is typically a commercially available pipe that can also be used in conventional processes. According to the invention, the term pipe (4) also includes hoses, i.e., flexible and bendable pipes, for example, a plastic hose. The pipe (4) can have a smooth, corrugated, or otherwise profiled surface. Corrugated hoses made of plastic and / or metal are thus included.

[0075] The diameter of the pipe (4) depends on the application and the quantity of fluid being conveyed. For smaller refrigeration units, it can be a thin pipe with a diameter of, for example, 1 cm or less. The term pipe (4) also includes pipelines or lines, provided they are suitable for conveying fluids as described in the invention.

[0076] The tube (4) is preferably a tube made of essentially one type of material and thus typically consists of a single layer. Accordingly, the tube (4) preferably does not consist of a plurality of different layers of different materials, as disclosed, for example, in WO-A-2011 / 161472 or WO-A-2012 / 175994.

[0077] For the purposes of the invention, the pipe (4) does not include pipelines or pipes for the petroleum or natural gas industry.

[0078] In a preferred embodiment, the tube (4) is a glass tube, a metal tube, in particular a brass tube, steel tube, stainless steel tube, aluminum tube, and / or copper tube, and / or a plastic tube, in particular a tube made of PVC, PET, acrylic glass, polyurethane, polycarbonate, polybutadiene, polypropylene, polyethylene and / or composite materials.

[0079] Suitable pipes (4) for hot water in building services engineering, for example for multi-story apartment buildings, typically have an inner diameter of about 0.5 cm to about 50 cm, in particular from about 1 cm to about 35 cm. The inner diameters are preferably measured with a caliper according to DIN 862, in particular with a caliper according to DIN 862 with vernier form A1.

[0080] The pipe (4) can have any cross-section. In many cases, the preferred cross-section is round. However, it can also be oval, ellipsoidal, rectangular (e.g., square), and / or angular. If the pipe is arranged in a spiral, for example, the entire spiral can be encased as if the overall diameter of the spiral were the diameter of the pipe (4). It is also possible—and often preferred—if the fluid media flowing in the pipe (4) are under pressure, i.e., have a pressure greater than 1 bar, for example, water in water pipes such as hot water, gases in refrigeration units, or steam in steam lines.

[0081] If the pipe (4) is first encased with the heat storage layer (1) and then with thermal insulation material (5) or with the heat storage insulation composite (51) according to process step b1), the encased pipe (41) obtainable according to the inventive method is obtained. The thermal insulation material (5)

[0082] The thermal insulation material (5) serves to insulate both the heat storage layer (1) and the pipe (4) and the fluid medium contained therein. This significantly slows down the temperature equalization with the ambient temperature. However, the thermal insulation is unsuitable for the purpose of heat storage, as the heat capacity of the thermal insulation materials (5) is generally too low.

[0083] The thermal insulation materials (5) have a thermal conductivity of ≤ 0.1 W / (m·K), preferably ≤ 0.07 W / (m·K), in particular ≤ 0.04 W / (m·K).

[0084] The optimal thickness of the thermal insulation material (5) depends on the specific application and individual needs, and the professional can easily make the appropriate choice.

[0085] It is often helpful if the thermal insulation material (5) completely encloses the pipe (4) and the heat storage layer (1).

[0086] Suitable thermal insulation materials (5) are known to the expert. Preferred non-limiting thermal insulation materials (5) include expanded polystyrene (EPS), extruded polystyrene (XPS), polyurethane (PUR), polyisocyanurate (PIR), phenolic resin (PF), flexible elastomeric foam (FEF), polyethylene foam (PEF), urea-formaldehyde resin foam (UF), rigid PVC foam, polyurethane spray insulation, rubber such as natural rubber or synthetic rubber such as styrene-butadiene rubber (SBR) or ethylene propylene diene monomer rubber (EPDM), mineral fiber, mineral foam, mineral wool (MW), rock wool, glass wool, foam glass (CG), expanded clay, perlite and expanded perlite (EPB), vermiculite and expanded vermiculite, aerated concrete, wood fiber insulation board (WF), wood wool insulation board (WW), cellulose insulation (CI), cork, cork granules, Cork board and cork insulation board (ICB), microporous insulation material, aerogel, vacuum insulation panel (VIP), vacuum insulation and / or insulation materials of animal and / or plant origin,such as insulation boards made of sheep's wool, reed boards, coconut fiber mats and / or flax fiber boards, wherein EPS, PU, ​​PIR, elastomer, rubber, styrene-butadiene rubber (SBR), ethylene propylene diene monomer (EPDM), FEF, stone, glass wool, glass foam and / or mineral foam are particularly preferred.

[0087] In one embodiment, foamed thermal insulation materials (5) are particularly preferred, with expanded or extruded organic polymers being especially preferred.

[0088] The thermal insulation material (5) and the unloaded heat storage insulation composite (51) can also have a vapor barrier in the cladding, i.e. in the outer layer.

[0089] The thickness of the thermal insulation material (5) can be chosen essentially arbitrarily and adapted to the specific requirements. In many cases, thicknesses of the thermal insulation material (5) of approximately 0.2 to 40 cm are suitable, preferably approximately 0.5 to 20 cm, and in particular approximately 0.5 to 10 cm, measured with a caliper according to DIN 862. The heat storage insulation composite (51; not claimed)

[0090] The unstressed heat storage insulation composite (51) is obtained by bringing the heat storage layer (1) into contact with, i.e., bonding it to, the thermal insulation material (5). It is particularly suitable for building services engineering. However, due to its dimensions, which allow for the encasing of pipes (4) with certain diameters, the heat storage insulation composite (51) can also be used for chemical and process engineering plants, especially in the field of specialty chemicals.

[0091] In a preferred embodiment, the thermal insulation material (5) has a profile, i.e., a recess, which allows the thermal insulation material (5) to be easily placed around the pipe (4). If this recess is enlarged somewhat, i.e., substantially by the thickness of the heat storage layer (1), the heat storage layer (1) can be inserted into this recess and advantageously fastened, i.e., clamped, screwed, nailed, fixed, and / or glued, thereby obtaining the unstressed heat storage insulation composite (51). Thus, the heat storage insulation composite (51) is in the form of a closable pipe shell, which may optionally be surrounded by a film, in particular a fiber-reinforced protective film.

[0092] The unloaded thermal storage insulation composite (51), particularly when it is in the form of a pipe shell, is advantageously manufactured at the factory. This allows the pipe (4) to be encased on-site, for example at the construction site, such that the thermal storage layer (1) of the thermal storage insulation composite (51) is located between the pipe (4) and the thermal insulation material (5) of the thermal storage insulation composite (51). Consequently, the thermal storage insulation composite (51) is also very well suited for retrofitting existing, permanently installed pipes (4) and conduits. The passive hot / cold keeping system for hot / cold water pipes

[0093] The passive hot water maintenance system and / or cold water maintenance system according to the invention, i.e., the hot / cold maintenance system for hot / cold water pipes, comprises at least one pipe (41) sheathed according to the invention. It is particularly suitable for pipes used in building services engineering, structural engineering, and chemical and process engineering plants.

[0094] In a preferred embodiment, the passive warming system does not have a circulation system with a circulation pump and therefore no return lines.

[0095] In another preferred embodiment, the passive hot / cold storage system requires no external energy input or output to function. In other words, the energy contained in the hot water is sufficient to supply the latent heat storage material (2) with the necessary enthalpy of fusion to heat and melt it, thus "activating" it. When the hot water flow is interrupted, the energy stored in the latent heat storage material (2) is released to the water over an extended period, keeping the water in the pipe above a defined temperature for hours, for example, 7 hours or more. No additional energy needs to be added during a flow interruption. Furthermore, no circulation system is required to keep the hot water sufficiently warm. And the cold water can quickly and easily access the energy stored in the latent heat storage material (2).The latent heat storage material (2) is dissipated and thus "activated" by transferring the enthalpy of fusion. If the flow of the cold water is interrupted, the enthalpy of fusion must first be replenished by means of external heat input, causing the latent heat storage material (2) to begin melting. With appropriate dimensions, this process takes hours, during which time the water remains cooled. Again, no energy needs to be added to cool the water if the flow is interrupted.

[0096] In a preferred embodiment of the passive heat retention system for hot water pipes, a latent heat storage material (2) with a phase change temperature of preferably about 40°C to 70°C, and in particular about 50°C to 60°C, is used. A suitable, non-limiting latent heat storage material (2) comprises myristic acid with a melting point of 54°C and an enthalpy of fusion of 199 kJ / kg.

[0097] In a preferred embodiment of the passive cold-keeping system for cold water pipes, a latent heat storage material (2) with a phase change temperature of preferably about -10°C to 20°C, and in particular about -2°C to 18°C, is used. Suitable non-limiting latent heat storage materials (2) include hexadecane with a melting point of 18°C ​​and a enthalpy of fusion of 210 kJ / kg, and tetradecane with a melting point of 6°C and a enthalpy of fusion of 225 kJ / kg.

[0098] Any of the aforementioned matrix materials (3) are suitable as matrix materials (3) for producing the heat storage layer (1).

[0099] The above-mentioned thermal insulation materials (5) are suitable as thermal insulation material (5) for producing a suitable, unstressed heat storage insulation composite (51) and / or for sheathing the pipe (4) covered with a heat storage layer (1) according to the invention, wherein foamed thermal insulation materials (5) are particularly preferred, and expanded or extruded organic polymers are especially preferred.

[0100] In a preferred embodiment of the passive hot / cold water system for hot / cold water pipes, the ratio of the thickness of the thermal insulation material (5) to the thickness of the heat storage layer (1) in the sheathed pipe (41) according to the invention is preferably from about 40:1 to about 0.5:1, more preferably from about 20:1 to about 1:1, and particularly from about 10:1 to about 2:1. For example, a suitable embodiment of the pipe (41) has a heat storage layer (1) comprising the latent heat storage material (2) with a thickness of 10 mm and the thermal insulation material (5) with a thickness of 30 mm. In another exemplary embodiment, the heat storage layer (1) has a thickness of 5 mm and the thermal insulation material (5) has a thickness of 50 mm. Example 1: Production of a heat storage layer (1)

[0101] As matrix material (3) 100 g of granular polymethyl methacrylate (PMMA) and 150 g of granular styrene-ethene-butene-styrene block copolymer (SEBS, manufacturer Kraton Polymers Inc.) were mixed together and premixed in the first zone, i.e. the pre-flow zone, of a commercially available twin-screw extruder at 250°C for 2 minutes.

[0102] In a 2.5-liter vessel, 740 g of paraffin with a melting point of 31 °C (RT31 from Rubitherm) and 1 g of hydrophobic, pyrogenic silica SiO₂ (silicon dioxide, Evonik) as nucleating agent and thickener were mixed and dispersed at 50 °C using a commercially available dispersing device (rotor-stator rod homogenizer from IKA) for 5 minutes at a shear rate of 20,000 s⁻¹. They were then added to the second zone of the extruder and mixed with the polymers of the matrix material (3) for 3 minutes at 250 °C PCM. The extrudate was subsequently cooled in a water bath and granulated to an average particle size of 3 mm, measured using a sieve.

[0103] A larger quantity of the granules was extruded in a Coperion ZSK-MC-18 extruder at T = 250°C and a residence time of 2 minutes to form a flat heat storage layer (1) with a layer thickness of 5 mm and a width of 0.5 m. For easier handling, both sides were then laminated with aluminum foil and the heat storage layer (1) was cut to size.

[0104] The heat storage layer (1) thus obtained is, for example, relatively inflexible at temperatures of 20°C, i.e., well below the melting point of the paraffin used; that is, it can be easily deformed plastically with some pressure. However, if the heat storage layer (1) – and thus all the paraffin, i.e., the entire quantity of latent heat storage material (2) – is heated to, for example, 40°C, i.e., well above the melting point of the paraffin used, the granules, as well as the heat storage layer (1) produced from them, are elastically deformable. The paraffin can be felt at the cut edges, but even when pressure is applied to the granules or the heat storage layer (1) with molten paraffin at 40°C, no paraffin oozes out. Thus, neither the granules nor the heat storage layer (1) bleed out, even when pressure is applied to the molten paraffin. The heat storage layer (1) thus obtained comprises 74 wt.-% Latent heat storage material (2) has a heat capacity, measured by DSC according to EN ISO 11357, of 140 kJ / kg heat storage layer (1). Example 2: Production of a sheathed pipe (41)

[0105] The flat heat storage layer (1) produced in Example 1, with a layer thickness of 5 mm, a width of 0.5 m, and aluminum lamination on both sides, was cut into strips 2 cm wide. A stainless steel pipe with an outer diameter of 5.4 cm was wrapped with a heat storage layer strip at an angle of approximately 45°. The wrapping was continued at the ends of the strips with another strip. The ends of the strips were optionally glued and / or wrapped with adhesive tape to secure the heat storage layer strips to the pipe.

[0106] In a subsequent step, the pipe (4), thus covered with the heat storage layer (1), was encased with thermal insulation material (5) in the form of a pipe shell, the pipe shell being in the form of a polyisocyanurate foam (PIR foam). The pipe shell has an inner diameter of 6.4 cm, a thickness of 5 cm, and a thermal conductivity of 0.027 W / (m·K). Advantageously, the longitudinally arranged opening of the pipe shell has a self-adhesive layer with which the pipe shell is subsequently sealed. The construction of such an encased pipe (41), which is enclosed with a pipe shell made of thermal insulation (5), is shown by way of example in Fig. 7 depicted. Example 3: Production of a sheathed pipe (41)

[0107] Example 2 was repeated, using a standard rubber hose with an outer diameter of 5 cm as the pipe (4). Additionally, a flexible polyurethane foam pipe shell with a thickness of 5 cm was used as the thermal insulation material (5).

[0108] The sheathed tube (41) thus obtained, i.e. the sheathed rubber hose, exhibits a comparably high flexibility even at temperatures significantly below the melting temperature of the latent heat storage (2) present in the heat storage layer (1) as without the heat storage layer (1). Example 4: Production of a heat storage insulation composite (51) and sheathing of the pipe (4) (not claimed)

[0109] Example 2 was repeated, using the same amount of myristic acid with a measured melting point of approximately 53°C and a fusion enthalpy of 199 kJ / kg as the latent heat storage material (2) instead of paraffin. The resulting planar heat storage layer (1) with a thickness of 10 mm, a width of 0.5 m, and aluminum lamination on both sides was cut into strips. The width was chosen to completely line the interior of the thermal insulation material (5). A hinged, two-part PIR foam pipe shell with a thickness of 5 cm and an outer diameter of 14.2 cm was used as the thermal insulation material (5) around the pipe with an outer diameter of 2.2 cm (see Figure 1). Fig. 3 , left half). A stainless steel pipe with a wall thickness of 1.2 mm and an outer diameter of 2.2 cm was encased in the heat storage insulation composite (51) thus obtained, which was not subjected to stress. Example 5:Determination of the temperature behavior of the passive hot / cold keeping system with hot / cold water pipes during flow interruption

[0110] In a climate chamber with constant room temperatures, an experimental setup was constructed to determine the temperature behavior of the passive hot / cold water system with hot / cold water pipes during a flow interruption. For the experiments with a water temperature of 60°C, a room temperature of 21°C (heated room in winter) was set, and for the experiments with a water temperature of 12°C, a room temperature of 26°C (summer temperature) was set.

[0111] The test setup comprises a 3-meter-long test and measurement section consisting of a linear, horizontally arranged stainless steel tube, the ends of which are connected to a thermostat. The fluid temperature was precisely set and maintained using the thermostat, with drinking water being used as the fluid. The necessary connecting lines from the thermostat to the tube and back were minimized and optimally insulated with thermal insulation material.

[0112] For the hot water tests, i.e., with a water temperature of 60°C, both a pipe with an outer diameter of 22 mm and a wall thickness of 1.2 mm and a pipe with an outer diameter of 54 mm and a wall thickness of 1.5 mm were used. For the cold water tests, i.e., with a water temperature of 12 to 13°C, a pipe with an outer diameter of 22 mm and a wall thickness of 1.2 mm was used. Following Example 4, the stainless steel pipes were encased with a different, non-loaded heat storage insulation composite (51). A swissporKISODUR PIR shell with a thermal conductivity of 0.027 W / (mK), a specific heat capacity of 1.4 kJ / (kg.K), and a bulk density of 32 kg / m³ was used as the thermal insulation material (5) of the heat storage insulation system (51). The respective composition can be found in the footnotes to Table 1.In addition, comparative tests were carried out with standard thermal insulation as well as completely without thermal insulation.

[0113] Along the test track, four temperature sensors were installed at regular intervals inside the stainless steel pipe to determine the water temperature in the pipe, whereby only the average temperature of the two middle temperature sensors is shown below.

[0114] The experimental setup was circulated for a sufficient length of time before each experiment to ensure that all the latent heat storage material (2) was in liquid (for hot water) or solid (for cold water) state.

[0115] Test series A and B demonstrate the cooling of warm water at a temperature of 60°C when the flow is interrupted in a stainless steel pipe with a diameter of 22 mm (test series A) and 54 mm (test series B), respectively. Without thermal insulation, the water cools down quickly. Due to its greater mass, the cooling of the warm water in the thicker pipe is somewhat slower (1 hour) than in the thinner pipe (20 minutes). If the pipe is then encased in a standard PIR foam with a thickness of 50 mm, the time until the limit of 48°C is reached increases by approximately a factor of 4. If a thin layer of a heat storage layer (1) comprising 75% of a suitable latent heat storage material (2) with a melting point of 53°C is placed between the pipe and the thermal insulation, the time until the limit of 48°C is reached increases significantly again.For the thinner pipe (test series A), a heat storage layer (1) thickness of 10 mm is sufficient to increase the time from 1.5 hours to 7 hours! For the thicker pipe, a heat storage layer (1) only 5 mm thick extends the time from 3.7 hours to 6.75 hours. And a heat storage layer (1) that is 25% thicker increases the time until 48°C is reached by a further 2 hours (with a slightly smaller thickness of the thermal insulation).

[0116] Test series C shows the heating of cold water at a temperature of 12 to 13°C when the water flow is interrupted in a stainless steel pipe with a diameter of 22 cm. Without thermal insulation, the limit of 20°C is reached within only 55 minutes.

[0117] If the pipe is encased in 30 mm thick thermal insulation made of commercially available PIR foam, the time it takes for the water temperature in the pipe to reach the limit of 20°C increases to 3.2 hours. If a thin layer of only 5 mm of a heat storage layer (1) comprising 75% of a suitable latent heat storage material (2) with a melting point of 17°C is now placed between the pipe and the thermal insulation, the time until the limit of 20°C is reached increases even further to 10.5 hours!

[0118] The experiments clearly show that even a thin layer of a heat storage layer (1) with a suitable latent heat storage material (2) between the pipe (4) and the thermal insulation (5) can significantly increase the cooling of hot water or the heating of cold water in hot / cold water pipes. It is irrelevant whether the inventive, sheathed pipe (41) is obtained by first covering a pipe (4) with the heat storage layer (1) and subsequently sheathing it with thermal insulation (5), or whether the pipe (4) is sheathed with an unloaded heat storage composite (51). The resulting passive hot / cold water system with hot / cold water pipes functions without an energy input and allows countless heating / cooling cycles without wear. It is also simple and inexpensive to manufacture and maintenance-free.

[0119] The present invention is explained in more detail below with reference to the following drawings, and non-limiting, preferred embodiments of the method according to the invention, the sheathed tube (41) obtained according to the invention, and the unclaimed heat storage insulation composite (51) are shown. These are not to be interpreted as limiting and are understood as part of the description: Fig. 1 shows an example of the logarithmically decreasing temperature profile of a warm fluid medium along the radius of a pipe (4) with thermal insulation material (5), from inside the pipe (4) to the pipe wall (marked d1) and further through the thermal insulation material (5) to the outside. The dotted line ( ········· ) schematically shows the temperature profile inside the thermal insulation material (5), where no latent heat storage material (2) is present between the pipe (4) and the thermal insulation material (5). The thermal insulation material (5) itself also does not contain any latent heat storage material (2). Thus, the dotted line represents a conventional, state-of-the-art design. The dashed line ( - - - ) schematically shows the temperature profile inside the thermal insulation, where conventional microencapsulated latent heat storage material (2) is incorporated into the thermal insulation.The temperature profile is shown while the latent heat storage material is not yet completely solidified, i.e., relatively soon after the flow through the pipe is switched off, and correspondingly soon after the holding period begins. Such thermal insulation materials are known in the literature. Even if microencapsulated latent heat storage material (2) is distributed throughout the entire thermal insulation, only that portion of the latent heat storage material (2) which is also in liquid form can serve as a heat storage medium; that is, the temperature within this area of ​​the thermal insulation must be at least equal to the melting point. However, the area within the thermal insulation that exhibits such high temperatures is generally extremely small (marked d2), particularly because the latent heat storage material (2) is also selected such that its melting point is only slightly below the temperature of the conveyed fluid medium.Consequently, the proportion of thermal insulation that can function as a heat storage medium is also very small. In contrast, the thermal insulation with microencapsulated latent heat storage material (2) exhibits increased thermal conductivity, which limits the effectiveness of the thermal insulation. As a result, both effects—i.e., temperature retention and reduced thermal insulation due to increased thermal conductivity—can even cancel each other out. The line with a dash-dot ( - · - ) schematically shows the temperature profile according to the present invention. The temperature inside the pipe (4) at the pipe wall (marked d1) also corresponds to the temperature inside the heat storage layer (1) (marked from d1 to d3). Only then does it decrease towards the outside within the thermal insulation material (5) (from d3 onwards). Fig. 2 shows the same. Fig. 1The exponentially decreasing temperature profile TR during flow interruption within the pipe (4). The dotted line ( ········· ) shows the temperature profile with only thermal insulation material (5) according to the prior art. The dashed line ( - - - ) shows the temperature profile with thermal insulation containing microencapsulated latent heat storage material (2) according to the prior art, and the line with dash-dot ( - · - ) shows the temperature profile of the pipe (4) encased according to the present invention. The temperature inside the pipe (4) up to time t 1 corresponds to the temperature of the fluid medium during flow, i.e., the temperature corresponds to the desired temperature. If the flow of the fluid medium is now stopped at time t 1, and the pipe (4) is protected from cooling only by the thermal insulation material (5), the temperature of the fluid medium inside the pipe (4) drops relatively quickly (dotted line ········· ).If the thermal insulation contains microencapsulated latent heat storage material (2) according to the prior art (dashed line - - -), the temperature initially drops only slightly and cannot be maintained. However, as soon as the portion of the microencapsulated latent heat storage material (2) that is in the immediate vicinity of the pipe (4) and thus in a molten state, i.e., at time t 2, has released its phase transition enthalpy, the temperature drops and the fluid medium cools down. With the heat storage layer (1), the temperature of the sheathed pipe (41) is maintained for a longer period of time (line with dash-dot - · -) even when the flow of the fluid medium is interrupted (time t 1), until all the latent heat storage material (2) has released its phase transition enthalpy to the surroundings via the thermal insulation material (5). Only then, i.e., at time t 3, does the fluid medium cool down.In practice, however, and with optimized layer thicknesses, this only occurs during unusually long interruptions, for example, during extended maintenance work. Fig. 3 shows the same. Fig. 2The measured temperature profiles of water with a flow temperature of 60°C after a flow interruption in a stainless steel pipe with an outer diameter of 22 mm and a wall thickness of 1.2 mm. The dotted line ( ········· ) shows the temperature profile in the pipe without thermal insulation material (5) and without a heat storage layer, according to the state of the art. The dashed line ( - - - ) shows the temperature profile with thermal insulation (5) made of commercially available PIR foam with a layer thickness of 50 mm, according to the state of the art.The line with a dash and dot ( - · - ) shows the temperature profile of the pipe (4) encased in an unloaded heat storage composite (51) made of commercially available PIR foam with a layer thickness of 50 mm and a 10 mm thick heat storage layer (1), where a temporary cap on the pipe temperature in the region of the melting point of the latent heat storage material (2) is clearly visible; see Example 5 and Table 1 for further details. By using the unloaded heat storage composite (51) with a heat storage layer (1) only 10 mm thick, the cooling time from 60°C to the set limit (fine, dotted and horizontal line) of 48°C can be increased from 1.5 hours to 7 hours! Fig. 4 shows a similar effect. Fig. 3The measured temperature profiles of water with a flow temperature of 60°C after a flow interruption in a stainless steel pipe with an outer diameter of 54 mm and a wall thickness of 1.5 mm. The dotted line ( ········· ) shows the temperature profile in the pipe without thermal insulation (5) and without a heat storage layer, according to the state of the art. The dashed line ( - - - ) shows the temperature profile with thermal insulation (5) made of commercially available PIR foam with a layer thickness of 50 mm, according to the state of the art. The line with dash-dot ( - · - ) shows the temperature profile of the pipe (4) encased in an unloaded heat storage composite (51) made of commercially available PIR foam with a layer thickness of 50 mm and a 5 mm thick heat storage layer (1).The line with dash-dot-dot-dash (- · · -) shows the temperature profile of the pipe (4) encased in an unloaded heat storage composite (51) made of commercially available PIR foam with a layer thickness of 48.75 mm and a 6.25 mm thick heat storage layer (1); see Example 5 and Table 1 for further details. When the pipe (4) is surrounded by the heat storage composite (51), a temporary cap on the pipe temperature in the region of the melting point of the latent heat storage material (2) is clearly visible. By using the unloaded heat storage composite (51) with a heat storage layer (1) only 5 mm thick, the cooling time from 60°C to 48°C can be increased from 3.7 hours to 6.75 hours. If a 6.25 mm thick heat storage layer (1) is used, the cooling time from 60°C to the set limit (fine, dotted and horizontal line) of 48°C can even be increased to 8.75 hours! Fig. 5 shows analogous results. Fig. 3The measured temperature profiles of water with a flow temperature of 12 to 13°C after a flow interruption in a stainless steel pipe with an outer diameter of 22 mm and a wall thickness of 1.2 mm. The dotted line ( ········· ) shows the temperature profile in the pipe without thermal insulation (5) and without a heat storage layer, according to the state of the art. The dashed line ( - - - ) shows the temperature profile with thermal insulation (5) made of commercially available PIR foam with a layer thickness of 30 mm, according to the state of the art. The line with dash-dot ( - · - ) shows the temperature profile of the pipe (4) encased in an unloaded heat storage composite (51) made of commercially available PIR foam with a layer thickness of 50 mm and a 5 mm thick heat storage layer (1); see Example 5 and Table 1 for further details.By using the unstressed heat storage composite (51) with a heat storage layer (1) only 5 mm thick, the warm-up time from 12 to 13°C to the set limit (fine, dotted and horizontal line) of 20°C can be increased from 55 minutes to 10.5 hours! Fig. 6 shows an example of an unstressed heat storage insulation composite (51) in the form of a pipe shell. The two halves are, by way of example, surrounded on the outside by a fiber-reinforced protective film, as indicated by the protruding flaps on the left and right. This holds them together and allows them to be easily placed around a pipe (4), whose outer diameter ideally fits flush with the inner diameter of the pipe shell.The left embodiment of the pipe shell has a continuous heat storage layer (1) which is surrounded on the outside by a continuous layer of thermal insulation material (5), while the right embodiment—as one exemplary embodiment—has three strips of the heat storage layer (1) which are embedded in recesses in the thermal insulation material (5). The heat storage layer (1) can be attached to the thermal insulation material (5), for example, by adhesive bonding, which is a preferred embodiment of the left heat storage insulation assembly (51), i.e., pipe shell half. Alternatively, the thermal insulation layer (1) can also be pressed into recesses in the thermal insulation material (5) and thus mechanically fastened. Fig. 7 shows, by way of example, a pipe (4) which is spirally surrounded by an elongated rectangular heat storage layer (1).Thermal insulation material (5) is arranged above this, for example in the form of a pipe shell made of thermal insulation material (5) or as a heat storage insulation composite (51) placed around the covered pipe (4). Alternatively, the covered pipe (4) can also be inserted into a sleeve made of thermal insulation material (5) or heat storage insulation composite (51). Together they form the sheathed pipe (41) according to the invention. Fig. 8 shows, by way of example, the heat storage layer (1) in the form of a composite (13) according to embodiment i). A layer (11) is attached to the lower side of the heat storage layer (1). For example, a composite (13) produced by extrusion from matrix material (3) and latent heat storage material (2) can be applied to the layer (11) and formed into the heat storage layer (1).The latent heat storage material (2) is arranged in finely dispersed domains within the matrix material (3), which typically forms a continuous phase in the composite (13). Fig. 9 shows an example of the heat storage layer (1) in the form of a composite (14) according to embodiment ii). A layer (11) is also attached to the lower side of the heat storage layer (1). In the illustrated composite (14), the latent heat storage material (2) is absorbed in a nonwoven fabric. Fig. 10 shows two exemplary embodiments of the heat storage layer (1) in the form of a composite (15), both arranged on a layer (11). A powder and / or granules (151), for example in the form of microencapsulated latent heat storage material (2), as in . Fig. 10arepresented, or in the form of powdered or granular carrier material (151) onto which latent heat storage material (2) is sorbed, as in Fig. 10b Figure 11 shows an example of the matrix material (3) in the form of chambers. For easier filling, the chambers can initially be open on one side. After filling, the chambers can then be covered with a layer (11) and thus sealed. The chambers can be filled, for example, with pure latent heat storage material (2), with the composite (13), the composite (14), the composite (15), and / or the composite (16), which comprises a latent heat storage material (2) and a thickener and is available, for example, in the form of a highly viscous liquid, a gel, a powder, granules, flakes, and / or a paste. Fig. 8 The last chamber is currently being filled with the composite (16).

Claims

1. Method for maintaining the temperature of fluid media in pipes even when the flow of the fluid media is interrupted, wherein the pipes are suitable for building services engineering, structural engineering, and chemical and process engineering plants, wherein a) in a first step, a heat storage layer (1) is produced comprising at least one latent heat storage material (2) and at least one matrix material (3), wherein, if the latent heat storage material (2) is present in the matrix material (3) in microencapsulated form, the matrix material (3) is not a thermal insulation material (5), and b) in a second step, the heat storage layer (1) is arranged around a pipe (4) and then the pipe (4) covered with the heat storage layer (1) is sheathed with thermal insulation material (5), thus obtaining a sheathed pipe (41), characterized in that the thermal insulation material (5) has a thermal conductivity of <_0.1 W / (m K) and is in the shape of a pipe shell.

2. Method according to claim 1, characterized in that at least one side of the heat storage layer (1) is covered by a layer (11), wherein the layer (11) is preferably a paper layer, a plastic film, in particular a polyethylene, PE, polypropylene, PP, polystyrene, PS, polyethylene terephthalate (PET) and / or plastic laminate film, a metal film, in particular an aluminum, copper, tin, zinc and / or steel film, a metal-plastic layer and / or a laminate, wherein the layer (11) may also be reinforced by means of fibers, in particular glass fibers, carbon fibers and / or plastic fibers.

3. Method according to claim 1 or 2, characterized in that the heat storage layer (1) essentially i. constitutes a composite (13), wherein the composite (13) is obtained by heating, mixing, and cooling of at least one latent heat storage material (2), at least one matrix material (3), and optionally at least one nucleation additive, wherein the composite (13) is optionally further processed into fibers, ii. constitutes a composite (14), wherein the composite (14) comprises the latent heat storage material (2) which is sorbed on the matrix material (3), wherein the matrix material (3) preferably represents a mat of fibers, a fabric and / or a flat porous material, wherein the mat of fibers and / or fabric may optionally comprise fibers produced from the composite (13), iii. constitutes a composite (15) comprising a powder and / or granulate (151) which is bonded to at least one matrix material (3), in particular an adhesive, wherein the powder and / or granulate (151) is preferably present as a microencapsulated latent heat storage material (2) and / or the latent heat storage material (2) is sorbed on a porous powder and / or granulate-shaped carrier material, iv. constitutes a composite (16) comprising the latent heat storage material (2) and a thickener, wherein the composite (16) is in the form of a highly viscous liquid, a gel, powder, granulate, flakes, and / or paste, and / or v. comprises a plurality of chambers made of matrix material (3), wherein the chambers contain latent heat storage material (2), wherein the latent heat storage material (2) is preferably present in pure form, as powder and / or granules (151), as a composite (13, 14, 15, 16) and / or mixtures thereof.

4. Method according to at least one of claims 1 to 3, characterized in that the amount of latent heat storage material (2) in the heat storage layer (1) is selected such that the solid / liquid heat capacity of the heat storage layer (1) within a temperature range of 10 K is at least 50 kJ, preferably at least 80 kJ, in particular at least 120 kJ, per kg of heat storage layer (1) and measured by DSC according to EN ISO 11357-1 and -4.

5. Method according to at least one of claims 1 to 4, characterized in that the heat storage layer (1) consists essentially of - 30 to 95 wt% latent heat storage material (2), - 5 to 70 wt% matrix material (3), and - 0 to 20 wt% of other components.

6. Method according to at least one of claims 1 to 5, characterized in that the latent heat storage material (2) has a melting point between -182°C and +175°C, preferably between -80°C and +150°C, in particular between -25°C and +125°C.

7. Method according to at least one of claims 1 to 6, characterized in that the latent heat storage material (2) comprises at least one organic compound, in particular a hydrocarbon, paraffin, alcohol, glycol, polyol, sugar, ketone, ester, ether, carboxylic acid, fatty acid, amide, a sulfur compound, phosphorus compound, and / or nitrogen compound, and / or an inorganic compound, in particular an inorganic salt, salt hydrate, water, and / or an aqueous mixture.

8. Method according to at least one of claims 1 to 7, characterized in that the matrix material (3) is a synthetic and / or natural polymer, in particular a polymer based on olefinic monomers such as acrylates, styrene and / or olefins, a block copolymer, a condensation polymer, a biopolymer, in particular a protein, a polysaccharide, and / or a natural fiber, a carrier material, a thickener and / or an adhesive.

9. Method according to at least one of claims 1 to 8, characterized in that the pipe (4) is a glass pipe, a metal pipe, in particular a brass pipe, steel pipe, stainless steel pipe, aluminum pipe and / or copper pipe and / or a plastic pipe, in particular a pipe made of PVC, acrylic glass, polyurethane, polycarbonate, polybutadiene and / or composite materials.

10. Method according to at least one of claims 1 to 9, characterized in that the thermal insulation material (5) is based on expanded polystyrene (EPS), extruded polystyrene (XPS), polyurethane (PUR), polyisocyanurate (PIR), phenolic resin (PF), flexible elastomer foam (FEF), polyethylene foam (PEF), urea-formaldehyde resin foam (UF), rigid PVC foam, polyurethane spray insulation, rubber, styrenebutadiene rubber (SBR), ethylene propylene diene rubber (EPDM), mineral fiber, mineral foam, mineral wool (MW), rock wool, glass wool, cellular glass (CG), expanded clay, perlite and expanded perlite (EPB), vermiculite and expanded vermiculite, aerated concrete, wood fiber insulation board (WF), wood wool insulation board (WW), cellulose insulation (CI), cork, cork granules, cork board and cork insulation board (ICB), microporous insulation, aerogel, vacuum insulation panel (VIP), vacuum insulation and / or insulation materials of animal and / or plant origin, such as insulation boards made of sheep's wool, reed boards, coconut fiber mats, and / or flax fiber boards.

11. Sheathed pipe (41) obtained by - a first step in which a heat storage layer (1) is produced comprising at least one latent heat storage material (2) and at least one matrix material (3), wherein, if the latent heat storage material (2) is present in the matrix material (3) in microencapsulated form, the matrix material (3) is not a thermal insulation material (5), and - a second step in which the heat storage layer (1) is arranged around a pipe (4) and then the pipe (4) covered with the heat storage layer (1) is covered with with thermal insulation material (5) in the form of a pipe shell, thus obtaining the sheathed pipe (41), wherein the sheathed pipe (41) is suitable for building services and domestic engineering as well as for process engineering systems, wherein the thermal insulation material (5) has a thermal conductivity of ≤ 0.1 W / (m.K), and the pipe (4) is preferably a glass pipe, a metal pipe, in particular a brass pipe, steel pipe, stainless steel pipe, aluminum pipe, or copper pipe; or a plastic pipe, in particular a pipe made of PVC, acrylic glass, polyurethane, polycarbonate, polybutadiene, or composite materials.

12. Passive heat retention system for hot water pipes and / or cold retention system for cold water pipes in residential and office buildings as well as for chemical and process engineering plants, comprising at least one sheathed pipe (41) according to claim 11.

13. Use of a sheathed pipe (4) according to claim 11 for keeping fluid media warm, in particular as a hot water pipe in buildings, water vapor pipes, pipes for transporting chemicals, bitumen, silicones, hot melt adhesives, and / or foodstuffs such as chocolate, and / or for keeping fluid media cold, in particular fluid media under pressure, gases and / or liquids, in particular coolants, chemicals, solvents with high vapor pressure, and / or foodstuffs such as dairy products and beverages.