Heat storage medium with higher capacity based on hydrated salt - with additive partic. formamide or N-alkyl-sulpho-succinamate

摘要

A heat storage medium is based on a compsn. contg. a material with a liq.-solid change of state, prone to undesirable depositing of a solid particle fraction which appears when the compsn. is at least at the phase change temp., such as Na2SO4.10H2O, Na2CO3.10H2O. The compsn. also contains a nucleating agent. The medium is obtd. by forming a suspension of the compsn. in a colloidal slurry of a thixotropic material such as attapulgite, sepiolite, bentonite. The medium also contains >=0.1% pref. >=0.5% of an additive which is an organic solvent e.g. formamide a dye e.g. azorutinol, or organic salt e.g. fatty acid salt. This additive has a dielectric constant >= that of water and pref. >=90, and a dipolar moment >about 3; it is chemically stable w.r.t. the other components of the medium. The medium is used partic. for solar heat storage, and can have a capacity of is approx. 90-100% of the theoretical value. Degradation of the medium during storage and discharge is reduced.