Experimental investigation of barium hydroxide octahydrate as latent heat storage materials

摘要

Phase change materials have a predominant role in heat storage technology. This paper focused on experimental study of barium hydroxide octahydrate (BHO-Ba(OH)(2)center dot 8H(2)O), which is a low temperature phase change material with the melting point at 78 degrees C and a large latent heat with reported values in a range of 233 kJ/kg to 332 kJ/kg. Despite the great advantage of large heat capacity, it has significant supercooling and phase separation phenomena during the cooling process, which has limited its application. In this paper, five nucleating agents have been added to BHO to suppress the supercooling phenomena, including sodium borate, copper powder, calcium fluoride, calcium chloride and calgon. The experimental results indicated that the addition of 1% copper powder, 1% calcium fluoride, and 1% calgon by weight can reduce the supercooling degree to 2.7 degrees C, 1.8 degrees C and 2.3 degrees C respectively. In addition, gelatin has been used to suppress the phase separation phenomenon. The results indicate that the addition of 1% gelatin can hinder the phase separation by observing obvious less solid accumulations after 30 thermal cycles. Moreover, the thermal conductivity, specific heat capacity and corrosion characteristics were also measured in the experiments. The nucleating and gelling agents have successfully minimized the supercooling and phase separation issues of Ba(OH)(2) center dot 8H(2)O, which is essential for its application as phase change material for thermal storage.