Experimental study on liquid seal and crystal surface morphology of barium hydroxide octahydrate

摘要

Molten barium hydroxide (BHO) with strong alkalinity will absorb CO2 in the air and denaturing part of BHO, so it is very important to treat it with liquid seal. In this paper, the effects of liquid seals with different cooling methods and white suspended substances on the phase change process of BHO were compared for phase change experiments, so as to study the influencing factors of powdery expansion of BHO and the crystal crystallization mode. The experimental results show that the probability of powdery expansion of BHO increases with the decrease of cooling rate. Liquid paraffin and high temperature silicone oil can play the role of air insulation, but will make BHO supercooling and powder expansion probability increase, some white powder suspended between molten BHO and liquid sealing material (BaCO3 attached to tiny bubbles) has a certain promoting effect on nucleating crystallization of BHO, and the supercooling degree of BHO without white powder will increase again, the surface of the BHO crystal shows a tight structure around the loose and porous center, known as a branch cavity structure, which becomes apparent as the cooling rate increases. This experiment provides a reference for the study of phase change materials in the field of phase change energy storage. (C) 2019 Elsevier B.V. All rights reserved.