The utilization of solar radiation to obtain high-temperature heat can be realized by multiplying it on the illuminated surface with solar concentrating technologies. High-temperature heat with significant energy potential can be used for many technological purposes, e.g. the production of heat, cold or electricity. The following paper presents the results of the experimental study, on the operation of the parabolic linear absorber in the parabolic concentrator solar system. The parabolic mirror with an aperture of 1 m and a focal length of 0.25 m focuses the simulated radiation onto a tubular absorber with a diameter of 33.7 mm, which is placed in a vacuum tube. The length of the absorber is 1 m. The installation is illuminated by the solar simulator, which allows to carry out tests under constant and repeatable conditions. The simulator consists of 18 metal halide lamps, with a nominal power of 575 W each with a dimming possibility of up to 60%. The paper presents preliminary results of heat absorption by the analysed absorber, temperature increment, collected heat flux, and the pressure drop crucial for the optimization of the absorber geometry.

Changes in energy fuel markets, the rise of renewables and the aging of existing coal-fired units are leading to increased popularization of research on potential pathways for restructuring power systems. One proposed concept is the Coal-to-Nuclear path, which involves the partial use of existing coal-fired power plant infrastructure in favor of the construction of nuclear units, which can reduce investment costs. An additional benefit is the ability to manage the workforce competencies identified within the coal-fired power unit, and which are also required for the effective operation of the nuclear unit. The article considers the possibility of repowering the Kozienice power plant in Poland from the perspective of the availability of water used to cool the power units. Three different nuclear reactor technologies that are potentially being considered for the construction of the first nuclear units in Poland were analyzed. The study showed that the lowest water flows in the Vistula river recorded in 2022, equal to 146 m3/s, make it impossible to simultaneously cool the nuclear units and ensure sufficiently low water temperatures from an environmental perspective. Nuclear units were shown to require about 1.55−1.67 times more water for cooling than typical coal-fired units.