In search of correct approaches for using heat balance relations in the theory of energetic materials combustion

• Heat balance relations are often used without sufficient theoretical basis. • The article exhibits examples of incorrect use of approximate thermal balances. • Experimental checking the balance relations is not available due to the lack of correct kinetic parameters of exothermic reactions. • The approaches corresponding to correct use of heat balance relations are described. Approximate heat balance relations are widely used in the theory of energetic materials (EM) combustion, but often without sufficient theoretical basis. In some cases this serves a source of erroneous information. Direct experimental validation of the balance relations is not available at present time due to the lack of reliable data on the kinetic parameters of exothermic reactions in the condensed phase of EM at high heating rates and temperatures of the reaction zone. Accordingly, all calculations of EM chemical transformations at high temperatures published so far in literature contain errors of unknown magnitude. The article provides examples of incorrect use of approximate thermal balances, including those which deal with the principle of equivalence between radiant flux and increased initial propellant temperature and with criterion of ignition in the form of equal rates at this moment of heat gain and heat loss from the reaction zone in the condensed phase. The approaches corresponding to correct using the heat balance relations are described.