Microcapsule geometry and nanomaterial enhancement of PCMs (sp07&sp11) for free heating applications
Allan T. Muzhanje, Hamdy Hassan
Abstract
Thermal analysis for the charging/discharging process of PCMs in different encapsulation geometries for free heating applications is performed. PCMs; sp07 and sp11 for cold climate conditions are simulated with Al2O3 and CuO nanoparticles (NPs) in circular, elliptical, rectangular, and square physical models. Complete mathematical equations of the physical model are constructed and solved using Ansys-fluent and validated using an experimental setup. Findings show that rectangular microcapsules have the shortest melting and solidification times, over 41% shorter than those of circular capsules. Minimum melting times of 79 and 135 min are realized using Al2O3 NPs with sp07 and sp11, respectively for a rectangular model. NPs inclusion increases the melting and solidification rates by 4.17–16.90%. Al2O3 NPs resulted in better thermal performances compared with CuO NPs. The largest free cooling and heating potential is 2.32K and 1.50K, respectively using sp07 with Al2O3 NPs and sp11 Al2O3 NPs, respectively for rectangular microcapsule. The study recommends sp11. Sp11 with 4 wt% Al2O3 NPs in a rectangular capsule achieved free heating and cooling degrees of 1.50K and 1.30K respectively. Complete solidification and melting times of 120 and 135 min with the largest heat transfer rates of 13.4 W and −11.6 W, respectively are achieved.