Segregation/cycling effects on thermophysical properties of salt hydrate phase change materials

Abstract

AbstractEnergy storage systems designers normally use the thermophysical properties of phase change materials (PCMs) from the manufactures/suppliers data sheet. Unfortunately, sometimes PCMs systems do not behalf according to supplier data sheet, especially after cycling use. Designing systems based on these unrealistic data sheet make the system operates at off design conditions most of time. The problem is substantially appears in salt hydrates PCMs systems. In this short communication, a case study of such discrepancies in air free cooling is addressed. The system design was based on SP24E PCM data sheet, but results showed that liquids and solidus lines cannot shown on the temperature transient history during charging and discharging process, and complete solidification and melting could not be obtained. For further detailed investigations; differential scanning calorimeter (DSC) tests were conducted for SP24E PCM and completely different results than supplier data sheet were obtained DSC tests showed (a) a wide range of temperature variation during melting and solidifications, (b) phase change starts and ends at lower temperatures compared with supplier data sheet, and (c) phase change latent heat is lower than the one listed in supplier data sheet.