Combustion Limits of Hydrogen Ammonia Mixtures

this is only an estimate. The formula is not applicable for near borderline mixtures or for cases when the combustion pressure grows significantly. To obtain reliable data either Kp or du should be directly measured. 

The value du and the minimum ignition energy are bound by a single-valued correspondence as is shown in Fig. 4.24 [29]. 

Therefore, the experimental data obtained for one of these parameters can be applied for the other. It is easily seen in Fig. 4.24 that the minimum ignition energy 0.02 mJ in the stoichiometric H2 + air mixtures corresponds to the critical gap du = 0.6 mm. This value is close to the value estimated by the aforementioned formula (du = 0.7 mm). 

The initial pressure effect on the critical gap for H2 + air mixtures is presented in Fig. 4.25, based on data from [33]. 

To complete this investigation of H2 + air mixtures. Fig. 4.26 presents a diagram of LCL for the binary fuel H2 + NH3 at downward (1) and upward (2) flame propagation. 

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