Aluminosilicate microspheres are a valuable fraction of coal fly ash with diverse applications due to their low density. Currently, there is no efficient and ecologically rational method of cenosphere recovery from fly ash. A combination of dry methods for the recovery of both fine ash particles and aluminosilicate microspheres from coal fly ash is presented. It is comprised of fluidised bed separation followed by screening and pneumatic separation in a free-fall air chamber. Fluidised bed separation was assisted by a mechanical activator to prevent agglomeration. This step reduced the portion of material that required further treatment by 52–55 wt.%, with the recovery of microspheres exceeding 97%. Then, the concentrates were individually subjected to pneumatic separation. The final separation product for the fly ash containing 0.64 wt.% cenospheres was a cenosphere concentrate that constituted about 17 wt.% of the initial fly ash. The recovery of cenospheres was around 81%. Usage of a combination of dry methods allowed for maintaining almost 83 wt.% of the raw material in its dry form. Furthermore, the produced fly ash grain fractions could be used for different industrial purposes.

The paper presents mathematical models which have been developed by the authors, and the results of which may be used to design an experimental refrigeration unit operating in the Stirling cycle. The systems engineered and based on Stirling cycle may be considered as an alternative to commonly employed internal combustion engines and Linde circulation cooling systems. The article presents a time discretization model assuming the cylinders as adiabatic spaces. The model enables the size optimization of all particular elements of the Stirling device such as: heat exchangers, the regenerator, the cylinders, piston motion and phase displacement. The advantage of modelling is the calculation speed when compared to modelling based on full Navier-Stokes system of equations (CFD) therefore enabling the dimensioning of the device. The results obtained using the simplified model have been verified by the other modelling type – that is the full 3D CFD, in which the whole working space including the heat exchangers and the regenerator has been modelled. Additionally, a dynamic MESH option has been applied in order to simulate the movement of the pistons in the cylinders

Wind power is currently one of the most promising energy sources, both in Europe andacrossthe world. In Poland, a large annual increase in the installed wind turbine capacity has been observed for many years. Power generation from wind turbines is related to wind parameters, which, in turn, result from changes in atmospheric conditions. This is why the observed wind speed has different values depending on time and place (location and altitude). This affects the amount of generated power and the continuity of its production. The authors of this article carried out an analysis of the potential of the diversification of wind energy sources in Poland. The research was conducted with the aim of assessing the variability of the potential production of electrical energy. The analysis concerned the volatility of the wind speed and the variability of available turbine power, as well as its distribution over appropriate points in the location grid-a set of combinations for every point in the location grid, aiming to present the effect of the diversification. For this purpose, the standard deviation in relation to the average power of wind turbines was selected as a comparative measure. The analyses were conducted based on historical wind measurements and data retrieved from the MERRA database. The results indicate that it is more advantageous for both the Polish power system and power plant owners (energy companies) to build smaller wind farms that are distant from each other and to group them in pairs in order to create a virtual power plant. Despite a wind-farm downtime of less than 15% for most of Poland in the analysed period, the existing power differences do not provide the possibility of ensuring continuity of energy supplies.

The results of thermal recycling of rubber in the fluidized bed are presented. Two different types of the bed material were used: sand and low density spheres (cenospheres). For two bed types, rubber decomposition time, as the mass and the bed temperature functions, were determined. Time of the samples residence time was calculated with the assumption, that reactor and the analytical block may be described with the well-stirred model. Time of samples decomposition, decrease with increasing temperature, as expected. It was also established, there are significant deviations between shirking core model, and obtained results of the residence time as a mass function. Cenospheric bed application allows to reduce of the process pressure drop, and caused shift of the gas decomposition products zone to the deeper region of the bed. Acoustic and optical effects confirmed significant differences between combustion of sand and cenospheric bed. Higher frequency of bubbles explosions and reduction of diffusive flames number were observed during incineration in cenospheric bed. The relationship between exhaust emission (VOC, CO, NOx) and type of the bed was not confirmed, the identical situation is observed for the samples combustion time. In the presented manuscript, the above physical quantity depends almost completely on sample type and bed temperature.