Impact of new multiple twisted tapes on treatment of solar heat exchanger M. Sheikholeslami, Seyyed Ali Farshad, M. Barzegar Gerdroodbary and Amir H. Alavi Eur. Phys. J. Plus, 137 1 (2022) 86 Published online: 03 January 2022 DOI: 10.1140/epjp/s13360-021-02157-6