Combustion induced rapid phase transition of CO/H2/O2/N2/CO2 mixtures

The oxy-combustion of hydrogen and carbon monoxide mixtures at initial atmospheric condition of temperature and pressure has shown the presence of intense peak overpressures, higher than the adiabatic value and oscillating pressure signal. In this thesis the observed explosion mode have been addressed to the rapid phase transition of super-heated liquid water produced by the combustion reaction and condensed on the vessel walls. Such complex phenomenon has to be included in the general explosion classification and it is due to the synergic coupling between a physical explosion (Rapid Phase Transition) and a chemical explosion (Deflagration). This mode has been named combustion-induced Rapid Phase Transition (c-RPT). c-RPT does not occur for CO/O2/N2 mixture because of the absence of hydrogen (no H2O in the products). The limiting value of H2 in CO/O2/N2 mixtures, for the c-RPT occurrence, has been identified as 1% in the fuel (H2+CO) . A general criterion for c-RPT peaks based on characteristic times of evaporation and combustion has been developed. When applying the criterion of c-RPT phenomenon to literature data, it turns out that they are often the result of c-RPT rather to Deflagration to Detonation Transition or Heat Explosion