Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
  • C09K5/02—Materials undergoing a change of physical state when used
  • C09K5/06—Materials undergoing a change of physical state when used the change of state being from liquid to solid or vice versa
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
  • C09K5/02—Materials undergoing a change of physical state when used
  • C09K5/06—Materials undergoing a change of physical state when used the change of state being from liquid to solid or vice versa
  • C09K5/063—Materials absorbing or liberating heat during crystallisation; Heat storage materials
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
  • C04B22/08—Acids or salts thereof
  • C04B22/085—Acids or salts thereof containing nitrogen in the anion, e.g. nitrites
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
  • C04B40/0028—Aspects relating to the mixing step of the mortar preparation
  • C04B40/0039—Premixtures of ingredients

Definitions

• the present invention relates to phase change materials (PCM) for storing thermal energy in the form of phase change heat based on lithium nitrate trihydrate and their use.
• PCM phase change materials
• Heat exchangers are usually used for this. They contain heat transfer media that transport heat from one place or medium to another. To dissipate heat peaks e.g. the heat is released into the air via a heat exchanger. This heat is then no longer available to compensate for heat deficits.
• Known storage media are e.g. Water or stones / concrete to store sensible ("sensitive") heat or phase change materials (PCM) such as salts, salt hydrates or their mixtures to store heat in the form of heat of fusion (“latent" heat). It is known that when a substance is melted, i.e.
• the quality of the heat depends on the temperature at which it is available again: the higher the temperature, the more versatile the heat can be used. Because of this, it is It is desirable that the temperature level drops as little as possible during storage.
• latent heat storage In the case of sensitive heat storage (e.g. by heating water), the entry of heat is associated with a constant heating of the storage material (and vice versa during unloading), while latent heat is stored and discharged at the melting temperature of the PCM. Compared to sensitive heat storage, latent heat storage therefore has the advantage that the temperature loss is limited to the loss during heat transport from and to the storage.
• Lithium nitrate trihydrate as PCM Lithium nitrate trihydrate as PCM.
• Shoka describes in JP 07118629 for a PCM based on a mixture of LiN0 3 and Mg (NO 3 ) 2 * 6H 2 O a nucleating agent made of BaZrO 3 .
• the task was to avoid the hypothermia of lithium nitrate trihydrate. There should be a maximum loading temperature of the PCM of
• a first subject of the present invention is accordingly a means for storing heat, comprising a) lithium nitrate trihydrate and b) a mixture of at least two compounds selected from the group consisting of magnesium nitrate, nickel nitrate and strontium nitrate,
• Magnesium acetate, nickel acetate and strontium acetate or their Hydrates which contain at least one compound of the nitrate group, and c) optionally higher-melting nitrates.
• a second object is the process for the preparation of an agent, characterized in that a) the mixture of at least two compounds selected from the group consisting of magnesium nitrate, nickel nitrate, strontium nitrate, magnesium acetate, nickel acetate and strontium acetate or their hydrates, at least one compound from the nitrate group being present , in water or a mixture with a suitable organic solvent, the proportion of the individual components in the mixture being in the range from 10 to 90 mol%, b) the solution is evaporated and the crystals obtained or the melt of the meltable hydrates are heat-treated are, c) the mixture obtained from b) is mixed with lithium nitrate trihydrate, optionally in gelled or thickened form, and melted and, after cooling, is crystallized below the melting point.
• the corresponding can also be used to produce pure nitrate mixtures
• Oxides, hydroxides or carbonates are reacted with nitric acid and heated.
• Another object of the invention is the use of the above-mentioned agent, optionally with auxiliaries, as a storage medium in latent heat storage, for thermostating buildings, in plaster or in or on blinds, and in air conditioning devices for
• agent according to the invention can be used in clothing
• Thermostat can be used.
• Thermostat in the sense of the present invention means both thermal insulation and thus keeping one constant
• a phase change material is defined as the inventive means for storing heat, which in combination with a
• Nucleating agent and possibly a higher melting nitrate is present.
• the nucleating agent is a mixture according to the invention of at least two compounds selected from the group consisting of magnesium nitrate, nickel nitrate, strontium nitrate, magnesium acetate, nickel acetate and strontium acetate.
• the nucleating agent contains at least one compound from the
• Nitrate group The respective hydrates of these compounds can also be used.
• Binary and ternary mixtures are preferably used.
• the systems magnesium nitrate-nickel acetate-strontium nitrate, magnesium nitrate-nickel acetate, nickel acetate-strontium nitrate, magnesium nitrate-strontium nitrate or their hydrates are particularly preferred. It has been found that the agents according to the invention show a significantly more reliable nucleation for supercooled lithium nitrate trihydrate melts than the BaZrO 3 or MgCO 3 and MgO mixtures described in the literature.
• hypothermia that occurs with a maximum overheating to 95 ° C is between 5 and 7 K.
• the composition of the mixtures is in the range from 10 to 90 mol%, preferably from 30 to 70 mol%.
• the salts are dissolved in water or in a mixture with organic solvents. It is preferably dissolved in water and its mixtures with acetone or alcohol.
• the solution is evaporated to dryness at temperatures between room temperature and 120 ° C., depending on the solvent used, and the crystals are then tempered. Annealing is 10-80 hours, preferably 48 hours at temperatures between 50 and 150 ° C, preferably at 100 ° C.
• meltable hydrates of these salts can also be used to form the mixtures.
• the repetition of the melting and crystallization step leads to an improvement in the crystallization. At 3 cycles, it is almost 5% to 7 K subcooling in almost 100% of the samples tested. It was found that even small amounts (a few microliters) of the mixtures crystallize with comparable hypothermia. This makes the material particularly suitable for microencapsulation.
• the PCM lithium nitrate trihydrate is melted with a share of 0.5 to 10% by mass of nucleating agent. 1 to 3 mass%, particularly preferably 2 mass%, of nucleating agents are preferably used.
• the melting temperature of lithium nitrate trihydrate is 29 ° C, in mixtures with nucleating agents and additives it is in the range of 18-29 ° C. After cooling below the melting point, the crystallization can also be initiated by acoustic or mechanical stress.
• alkali metal or alkaline earth metal nitrates can optionally be added.
• Sodium and / or magnesium nitrates can preferably be used.
• the alkali metal or alkaline earth metal nitrates can be added to the PCM in amounts of between 1 and 50% by mass, preferably between 5 and 15% by mass.
• the PCM can optionally be gelled or thickened.
• auxiliaries known to the person skilled in the art can be added to the PCM, such as, for example, derivatives of cellulose or gelatin.
• the mixtures of PCM and nucleating agents according to the invention can, if appropriate with the addition of further auxiliaries, be microencapsulated or macroencapsulated.
• Microencapsulated mixtures of PCM and nucleating agent can be used in clothing for thermostatting.
• composition of the mixtures takes place in a range between
• an aqueous solution consisting of ⁇ 5 the salts in the above ratio, or a mixture of the meltable
• aqueous solution is evaporated to dryness at about 100 ° C. and the crystals are preferably for a while
• the PCM lithium nitrate trihydrate 2 ° is mixed with a proportion of> 1 mass% nucleating agent.
• the annealing conditions are summarized in Table 1. In the subsequent cooling step at 1 K / min, the crystallization temperatures are recorded, which are also shown in Table 1.
• the nucleating agents 5/2/1 and 2/3/6 are used to carry out DSC measurements between 5 and 95 ° C at a heating rate of 2 K / min on sample volumes in the ⁇ l range. The results are shown in Table 2.

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• 2002
  • 2002-05-08 DE DE10220516A patent/DE10220516A1/de not_active Withdrawn
• 2003
  • 2003-04-16 CN CNA038103818A patent/CN1653156A/zh active Pending
  • 2003-04-16 CA CA002487239A patent/CA2487239A1/en not_active Abandoned
  • 2003-04-16 JP JP2004503579A patent/JP2005524755A/ja active Pending
  • 2003-04-16 AU AU2003240454A patent/AU2003240454A1/en not_active Abandoned
  • 2003-04-16 US US10/513,655 patent/US20050167633A1/en not_active Abandoned
  • 2003-04-16 KR KR10-2004-7017805A patent/KR20050005467A/ko not_active Application Discontinuation
  • 2003-04-16 EP EP03729928A patent/EP1501908A1/de not_active Withdrawn
  • 2003-04-16 WO PCT/EP2003/004009 patent/WO2003095584A1/de not_active Application Discontinuation

Non-Patent Citations (1)

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