Numerical study on melting and heat transfer characteristics of paraffin wax/SiC paraffin using enthalpy-porosity model

The present numerical study addresses the buoyancy assisted transient two-dimensional early-stage heat transfer and melting process of PCM's in a square enclosure. Two PCM materials are used namely pure paraffin wax and paraffin with 1 mass % fraction of SiC nano particles. The square enclosure walls are subjected to a constant temperature of 65 degrees C (Hot wall) and 27 degrees C (Cold wall) at bottom and top side, respectively, while remaining sides of the enclosure are perfectly insulated. A finite volume (FVM)-based Ansys fluent software along with enthalpy-porosity method is used to capture the phase change process from solid to liquid. The pressure-velocity coupling is performed by coupled scheme, while pressure correction is done by PRESTO method. The transient variation of PCM liquid fraction, temperature, velocity and enthalpy are plotted. The results obtained shows that a notable difference is confined between early melting stages of both paraffin and nano-enhanced paraffin materials. The close observation of velocity vectors clearly shows that the addition of SiC nanoparticles in pure paraffin improves the convective heat transfer rate with time. The addition of SiC nano particles in paraffin reduces the melting time of paraffin but contrary influence the uniformity in temperature distribution and heat transfer characteristics. The presence of SiC nanoparticles increases the liquid fraction and temperature rise by 33% as compared with pure paraffin.