Experimental study of the multi-factor coupling effect of coal dust explosion intensity based on Box-Behnken response surface

Using the Box-Behnken experimental design method, the influence of multi-factor coupling effects on the intensity of coal dust explosion during the transient explosion reaction process was studied. Forty-five sets of explosion tests were carried out in a 20L spherical explosion test system, examining the macroscopic characteristics of the coal dust explosion intensity under the coupling effects of five factors: coal dust concentration (ρ), coal dust particle size (D), coal volatile matter (w), ignition energy (E), and ignition delay (t_d). The explosion process was monitored by measuring pressure changes, and the maximum explosion pressure (response value p_max) and the maximum explosion pressure rise rate (response value $ {\dot{p}}_{\max } $) were determined from the pressure-time curve. The Design-Expert software was used to analyze the experimental results to establish a quadratic regression model for response values p_max and $ {\dot{p}}_{\max } $, and the models were verified by four different methods. The results show that in the variance analysis, the coefficient of determination R² for p_max and $ {\dot{p}}_{\max } $ is 0.9771 and 0.9258, respectively, indicating a good fit between the model and experimental data. The single factors with the greatest influence on the maximum explosion pressure (p_max) are ignition energy (E) and ignition delay(t_d), while the single factors with the greatest influence on the rise rate of the maximum explosion pressure ($ {\dot{p}}_{\max } $) is coal dust particle size(D) and ignition delay(E). In the quadratic regression model, the significant two-factor interaction affecting p_max are ρD, ρE, ρt_d, Dw, wE, wt_d, and Et_d, wheras the significant two-factor interaction affecting $ {\dot{p}}_{\max } $ are ρt_d, Dw, Dt_d, wt_d, and Et_d. Among these, ignition delay (t_d) plays a decisive role in response values p_max and $ {\dot{p}}_{\max } $.