Efficiency of fire suppression systems using dry powder sprays to extinguish fires amid non-steady heat exchange processes and heterogeneous inhibition of active flame centres by powder particles

Introduction. Presently, there are several problems in the field of dry powder fire suppression that require the indepth study of the physics and technology of fire suppression processes using these substances. One of the ways to find the solution to these problems is the efficiency analysis (theoretical and experimental) of frequently implemented fire extinguishing patterns involving fire suppression systems spraying dry powder, when the term of interaction between the dry fire extinguishing powder and the burning material is close to the duration of principal fire extinguishing patterns, or thermal and heterogeneous inhibition of active flame centres. Purpose and objectives. The purpose of the work was to assess the efficiency of principal fire extinguishing patterns (thermal and heterogeneous inhibition of active flame centres) amid non-stable heat exchange processes and heterogeneous inhibition of active combustion product particles by powder particles. Methods. The pre-set objective was achieved through theoretical modeling of patterns of thermal fire extinguishing and heterogeneous inhibition of active flame centres by dry chemical powder particles. Results. It was established that fire suppression with the help of general purpose dry chemical powder under non-steady conditions is the more effective, the smaller the effective size of powder particles, the longer the time of their stay in the combustion area and the shorter the characteristic period of heat transfer to powder particles and heterogeneous inhibition of active flame centres. Conclusions. The results optimize conditions and patterns of dry fire extinguishing powder application to a combustion area to achieve the highest extinguishing effect and to conduct a targeted search for new dry chemical powders having pre-set thermal and physical specifications.