Compositions – Frost-preventing – ice-thawing – thermostatic – thermophoric,...
Patent
1997-10-20
2000-02-08
Green, Anthony
Compositions
Frost-preventing, ice-thawing, thermostatic, thermophoric,...
252 71, 252 74, 126910, 16510415, 16510417, C09K 500, C09K 506
Patent
active
060224878
DESCRIPTION:
BRIEF SUMMARY
The invention pertains to a heat-transfer concentrate, a process for its preparation, as well as its use for thermochemical energy storage for producing chemical heat pumps or for chemical heat transformation, and moreover, a latent heat-storage device.
In direct utilization of solar energy, for example recovery of heat with solar collectors, the economic storage of heat (and other energy) in heat-storage devices in which sensible or latent heat can be stored is a central question, since the heat losses increase with increasing storage time. Thus, for storage of sensible heat, water constitutes the simplest storage medium but it is uneconomical for long-term storage devices. Other storage media are latent heat-storage devices that use latent heat taken up and given off during phase transitions such as the heat of melting, heat of vaporization, and heat of crystallization.
Latent heat-storage devices are known and contain water, Glauber's salt, natural stone, synthetic stone, or fired alumina such as chamotte as the heat-storage medium. Although water with a specific heat capacity of 4.18 kJ/kg.multidot.K (kilojoule per kilogram.times.Kelvin) has the highest specific heat capacity of all elements, a storage temperature of greater than 82.degree. C. is problematical since at this temperature, the minerals dissolved in the water precipitate and deposit as so-called boiler scale. Due to the boiling point of 100.degree. C. at standard pressure and the resulting increasing vapor pressure, pressure problems arise with increasing temperature.
For Glauber's salt, the melting or solidification temperature in the aggregate change of state from solid to liquid or vice versa, from liquid to solid, must be considered in heat-storage. However, Glauber's salt only permits a limited number of aggregate changes of state. Thereafter it remains in the liquid state.
For natural stone materials such as, e.g., basalt, or synthetic stones or fired alumina such as chamotte, use as a heat-storage device is limited to high temperatures due to the low specific heat capacity.
Heat-transfer fluids (HTF) with addition of metal dusts are known, which however cannot be used in the chemical industry in chemical reactors with heat exchangers since in case of a tube rupture, there is a high risk of explosion due to the fine metal particles, especially metal particles, such as lead or mercury which must not reach the soil due to their high toxicity.
It was therefore the goal of the invention to create a heat-transfer concentrate for heat-transfer media for storage or for transport of heat that allows inexpensive storage of heat, is stable, nontoxic, and not explosive, as well as indicating a process for its preparation and its use, and a high-capacity latent heat-storage device.
The object of the invention is therefore a heat-storage concentrate characterized by a storage-stable dispersion of a heat-transfer medium and at least one fine-particle and/or high-porosity solid to which gallium has been adsorbed.
An additional object of the invention is a process for preparation of this heat-transfer concentrate which is characterized by the fact that a heat-transfer medium with at least one fine-particle and/or high-porosity solid and gallium, preferably in liquid form, are mixed, and the gallium is caused to homogeneously adsorb to the fine-particle and/or high-porosity solid as a result of mixing and the effects of the high mixing energy, e.g., using a high-speed homogenizer, and the solid particles laden with gallium are homogeneously dispersed.
An additional object of the invention is a heat-transfer mixture prepared from the heat-transfer concentrate prepared as per the invention, as well as a heat-transfer medium.
An additional object of the invention is the use of the heat-transfer concentrate of the invention in heat-transfer mixtures for storage and transfer of heat in reactors with heat exchangers, for use in heat pumps, and as a medium for thermochemical energy storage.
An additional object of the invention is a latent heat-storage devi
REFERENCES:
patent: 3882033 (1975-05-01), Wright
patent: 4099557 (1978-07-01), Bricard et al.
patent: 4099558 (1978-07-01), Bricard et al.
Bauer Heinrich
Daume Jochen
Grimm Arnold
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