This paper presents the results of testing the content of 5-hydroxymethylfurfural (HMF) in honey from Greater Poland. The production of honey from this area of Poland, its processing, and its consumption are closely related to the sustainable development of this region. It is created in the process of the production, storage, and transport of honey, especially during its thermal processing. Therefore, it can be an indicator in the analysis of sustainable development throughout the life cycle of honey and its products. The aim of this research was to determine the HMF content in Greater Poland’s honey available on the Polish market using three different methods and to compare the obtained results. The methodology used was as follows: two spectrophotometric methods (White and Winkler) and an HMF determination method based on the LC-MS/MS technique developed especially for this study. The determined HMF content in all tested honey samples did not exceed the applicable standard. The determined HMF values in all honey samples ranged from 0 to 28.5 mg HMF/kg honey. All results fell within the scope of European Council Directive 2001/110/EC of 20 December 2001, i.e., they did not exceed the HMF content in honey, which is 40 mg/kg. The results will encourage modifications to the universal honey testing procedures to be developed for the agri-food sector. In the study, seven honeys of different origins and types were selected; three HMF detection methods were selected; a comparative procedure was developed; and the content of the reference ingredient in honey was determined.

This work presents coal analyses for heavy metal content (Tl, Cu, Zn, Cd, Fe). The tested coal samples came from a Russian deposit in the Kuzbass Basin (Novosibirsk and Kemerovo Oblasts, near Kazakhstan) and from Poland. The concentration of thallium in coal was determined using DPASV—differential pulse anodic stripping voltammetry—and other metals were examined with FAAS, i.e., flame atomic absorption spectrometry. The study confirmed the presence of thallium in the tested coal sample. The coal samples from outside the European Union contained four times more thallium (the maximum content of thallium in coal has been determined to be 0.636 mg·kg⁻¹) than the samples of Polish coal (where the maximum content of thallium was 0.055 mg·kg⁻¹). Cadmium concentration was on average 1.99 mg·kg⁻¹ in the samples from outside the European Union, and 1.2 mg·kg⁻¹ in the samples of Polish coal. Zinc concentration in the samples from outside the European Union was on average 11.27 mg·kg⁻¹, and in the samples of Polish coal approx. 7 mg·kg⁻¹. In addition, iron concentration in all coal samples was determined as 14.96 mg·kg⁻¹, whereas copper concentration in the samples from outside the European Union averaged as 3.96 mg·kg⁻¹. The obtained results do not show any correlation between the presence of thallium and the presence of other metals. It is worth noting that heavy metals pose a threat to living organisms due to their persistence and bioaccumulation, particularly in the context of dust emissions to the atmosphere.

The paper presents the results of calculations related to determination of temperature distributions in a steel pipe of a heat exchanger taking into account inner mineral deposits. Calculations have been carried out for silicate-based scale being characterized by a low heat transfer coefficient. Deposits of the lowest values of heat conduction coefficient are particularly impactful on the strength of thermally loaded elements. In the analysis the location of the thermocouple and the imperfection of its installation were taken into account. The paper presents the influence of determination accuracy of the heat flux on the pipe external wall on temperature distribution. The influence of the heat flux disturbance value on the thickness of deposit has also been analyzed.

Low-power boilers fueled with solid fuels comprised a group of most rapidly technologically advancing traditional equipment in Poland. New energy/emissions related criteria are the most influencing factors in this respect. They clearly put a lot of emphasis on the reduction of emission from the 'distributed energy sector'. The authors have attempted to investigate the possibilities of application of modern numerical methods in improving the efficiency of low-power heating equipment. In order to validate the obtained results of numerical calculations, a series of experimental investigations has been performed that directly referred to the simulation and confirmed the applicability in this sector.

In the paper, the results of numerical simulations of the steam flow in a shell and tube heat exchanger are presented. The efficiency of different models of turbulence was tested. In numerical calculations the following turbulence models were used: k-ε, RNG k-ε, Wilcox k-ω, Chen-Kim k-ε, and Lam-Bremhorst k-ε. Numerical analysis of the steam flow was carried out assuming that the flow at the inlet section of the heat exchanger were divided into three parts. The angle of steam flow at inlet section was determined individually in order to obtain the best configuration of entry vanes and hence improve the heat exchanger construction. Results of numerical studies were verified experimentally for a real heat exchanger. The modification of the inlet flow direction according to theoretical considerations causes the increase of thermal power of a heat exchanger of about 14%.