1. Department of Heat, Hydraulics and Environmental Engineering, University of Ruse “Angel Kanchev”, 7017 Ruse, Bulgaria
2. Department Chemistry and Hydrogen Energy, Kazan State Power Engineering University, 420066 Kazan, Russia
3. Department Nuclear and Thermal Power Plants, Kazan State Power Engineering University, 420066 Kazan, Russia
4. Agricultural Machinery Department, University of Ruse “Angel Kanchev”, 7017 Ruse, Bulgaria