Phase change-type heat storage materials - based on hydrated magnesium nitrate

摘要

A novel phase change-type heat storage material comprises (i) Mg(NO3)2.xH2O (x = 2-4); or (ii) Mg(NO3)2.xH2O (x = 0-9) mixed with alkali and/or alkaline earth metal nitrates. Pref. type (ii) materials, comprising (a) a mixt. of Mg(NO3)2.6H2O and LiNO3 in a 9:1 wt. ratio, (b) the eutectic Mg(NO3)2.2H2O+Mg(NO3)2 and (c) the eutectic Mg(NO3)2.6H2O+Mg(NO3)2.2H2O, are specifically claimed. USE/ADVANTAGE - The materials are esp. useful for storing automobile engine waste heat and, in the case of material (b), for process and electrical heat storage. They have suitable melting pts. (e.g. 75 deg.C for material (a) and 127.7 deg.C for material (b)), are heat stable (e.g. material (a) can be heated to 125 deg.C without decomposition), are non-etching and non-corrosive, and have a high crystallisation or melting enthalpy.