Salt Water Solutions as PCM for Cooling Applications
Abstract
The objective of the paper is for experimentally studying and analysing aqueous salt solutions of sodium chloride (NaCl) and potassium chloride (KCl) that could be candidates of phase change materials (PCM) for the cooling applications and cold storage systems. These salts were selected because of their easy availability at low cost. Total 16 aqueous salt solutions of 8 different concentrations each of the NaCl and KCl were prepared and analysed by cyclation and corrosion tests. Cyclation tests were performed in temperature range of -24 ºC to -10 ºC to check feasibility of their use for cooling applications. KCl-H2O mixtures were analysed with 1% glycerine to avoid volume expansion. Results showed that KCl-H2O has more phase segregation than NaCl-H2O. Overall, melting-freezing temperature ranges of these mixtures are from -20 ºC to -3 ºC, which is feasible for the cold storage. However, all the 16 solutions showed subcooling. Corrosion tests were performed during 1 week and 1 month using 5 different common metals (Aluminium, Stainless steel, Laminated black steel, Copper and Galvanized steel) immersed in these 16 aqueous salt solutions to check their long term compatibility and corrosion rate of the metal-PCM pairs. 1 week results showed that 5% KCl with copper and galvanized steel and 21% NaCl with galvanized steel have highest corrosivity, while during 1 month, galvanized steel gave high corrosivity with 15% KCl and 21% NaCl.