Estimation of usage efficiency of freon-steam turbines in mine energy complexesMykhailo Kirsanov, Inna Diakun, Vitalii Ruban, Viktor Skosyriev and Oleksandr ZhevzhykE3S Web Conf., 168 (2020) 00048DOI: https://doi.org/10.1051/e3sconf/202016800048