فهرست نشریات علمی دسترسی آزاد ایران

The study focuses on four key indicators selected from eleven parameters characterizing hard coal quality. It presents and substantiates statistical approaches for processing the results of interlaboratory comparison testing, with particular attention to the assessment of sample homogeneity and stability. The stages of organizing and conducting interlaboratory comparisons are described, taking into account the specific features of fuel and energy sector enterprises. Selected statistical methods were applied to analyze coal quality indicators and to evaluate the reliability of the obtained measurement results. Based on the analysis, recommendations were developed to improve measurement procedures, enhance the interpretation of statistical outcomes, and increase the reliability and trueness of test results. The findings may be applied by fuel and energy enterprises in the validation and optimization of measurement procedures for hard coal quality indicators. The interlaboratory comparison involving 63 laboratories demonstrated that the measured values of gross calorific value (32225–32275 kJ/kg), volatile matter yield (11.558–11.73%), ash content (8.68–8.74%), and mass fraction of total sulfur (0.241–0.256%) are comparable and fall within permissible limits, with no outliers detected according to robust statistical analysis. These results confirm the homogeneity of the prepared coal samples and the reliability and consistency of the measurement procedures used by participating laboratories.