# Measurement of Instantaneous Mass Flow Rate of Polypropylene Gasification Products in Airflow
## 6 Conclusions  
A simple semi-empirical method for determining the instantaneous mass flow rate of gasification products of low-melting solid materials in a flow-through gas generator was proposed. The method is based on measuring the instantaneous mass flow rate of gas mixture at gas-generator inlet and outlet by gas-dynamic techniques. We presented the procedures of calculating the air mass flow rate at the gas-generator inlet, the mass flow rate of gaseous mixture at the gas-generator outlet, as well as the mass flow rate and yield of gasification products. The corresponding measurement errors were estimated. To demonstrate the method, a series of over 100 test fires of flow-through gas generator with polypropylene sample gasification was conducted using ambient-temperature air as a gasifying agent. The ignition of a polypropylene sample was triggered either by short-term hydrogen injection and ignition or by activating a pyro-charge during 0.1-0.5 s. After sample ignition, the gasification process was continued due to sample combustion in the air flow. The application of the proposed method for processing experimental data for the nine selected typical test fires showed that the time-averaged yield of polypropylene gasification products varied from 43 to 120 g/s, while the ratio of the mass of air to the yield of gasification products varied from 2.30 to 2.90. The results of other experiments not discussed herein confirm the applicability of the proposed method for determining the mass flow rate of gasification products. The universality of the proposed method was confirmed by applying two different schemes of gas generator: one with hydrogen ignition and another with pyro-charge ignition. The method can be readily applied to low-melting solid materials other than polypropylene if they are gasified without formation of liquid phase (condensate), since the method is based on gas dynamic relationships not generally applicable to the two-phase flows containing liquid or solid particles.  
Further work will be focused on the uncertainty analysis of the proposed method.  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline  & **Test Fire** & **6** & **7** & **8** & **9** \\ \hline Start of combustion, s & 1.30 & 1.25 & 1.33 & 1.32 \\ End of combustion, s & 5.10 & 5.37 & 5.40 & 5.48 \\ Air mass flow rate, g/s & 166.4 & 159.79 & 156.4 & 124.8 \\ Mass of air, g & 632.4 & 658.0 & 636.4 & 519.3 \\ Mass flow rate of gasification products, g/s & 71.2 & 67.0 & 65.0 & 43.0 \\ Yield of gasification products, g & 270.7 & 276.2 & 264.7 & 179.0 \\ Ratio of mass flow rates of air and gasification products & 2.34 & 2.38 & 2.40 & 2.90 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Operation parameters of GG at pyro-charge-assisted ignition.  
**Author Contributions:** V.I.Z.: conceptualization, methodology; D.A.V.: investigation; D.G.N.: investigation; S.M.F.: writing--original draft and editing, project administration. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was financially supported by the Ministry of Science and Higher Education of Russian Federation under state contract N13.1902.21.0014 (agreement N075-15-2020-806).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available upon request from the corresponding author.  
**Conflicts of Interest:** The authors declare no conflict of interest.