Entropy generation for spiral heat exchanger with considering NEPCM charging process using hybrid nanomaterialAhmad Shafee, M. Jafaryar, Metib Alghamdi and Iskander TliliEur. Phys. J. Plus, 135 3 (2020) 285DOI: https://doi.org/10.1140/epjp/s13360-020-00284-0