Efficiency of using heat pumps with various refrigerants in real steam turbine power units with PT-80 and T-250 turbinesVitaliy Sergeyev, Irina Anikina, Konstantin Kalmykov and Ivan NaletovE3S Web Conf., 140 (2019) 10001DOI: https://doi.org/10.1051/e3sconf/201914010001