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Prediction of Ignition Delay Times for Amine-based Liquid Propellants through a QSPR Approach

Zohari Narges, Pakdehi Shahram Ghanbari, Zarei Rohollah

Central European Journal of Energetic Materials

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2024

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Vol. 21, no. 1

68--79

EN

Decreasing the ignition delay time in the combustion chamber of a rocket engine is required from a safety point of view. However it takes a lot of time and money to find the most suitable compounds with a low ignition delay time. In the present research, a model is proposed to predict the ignition delay time of aminebased liquid propellants through the quantitative structure-property relationship (QSPR) method. This model was derived based on 35 data sets collected from reliable references and by the selection of appropriate descriptors using multivariate linear regression (MLR). The determination coefficient, mean absolute deviation and root mean square deviation of the new model were 0.9901, 2.51 and 3.19 ms, respectively, which indicates high reliability. Furthermore, the values of the cross validation coefficients of the new proposed model were Q²LOO = 0.9903 and Q²LMO = 0.9906, which confirm its sufficient validation. The most important variables which have an effect on the ignition delay time of amine-based liquid propellants were identified as the elemental composition, temperature and the percentage ratio of oxidizer to fuel (O/F).

2

Effect of Some Inorganic Nitrate Salts on the Ignition Delay Time of DMAZ-IRFNA and DMAZ-WFNA Bi-propellants

Pakdehi S. G., Shirzadi B.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 1

162--174

EN

Dimethylaminoethyl azide (DMAZ) is a good replacement for the hydrazine group in the space industry. However, it has a relatively long ignition delay time with the liquid oxidizer, white fuming nitric acid (WFNA), and is nonhypergolic with inhibited red fuming nitric acid (IRFNA). In this article, the ignition delay times of DMAZ-WFNA and DMAZ-IRFNA bi-propellants were reduced by the addition of some inorganic nitrate salts, such as NH4NO3, KNO3, NaNO3, AgNO3 and LiNO3, to the liquid oxidizers. The results showed that WFNA containing 0.1 wt.%, 0.3 wt.% and 0.5 wt.% of LiNO3 reduced the ignition delay time of DMAZ-WFNA from 88 ms to 18 ms, 14 ms and 8 ms, respectively. The same percentages of LiNO3 caused the nonhypergolic DMAZ-IRFNA bi-propellant to have ignition delay times of 42 ms, 34 ms and 22 ms, respectively. Moreover, calculations indicated that the addition of LiNO3 to both oxidizers did not have a significant affect on the specific impulse of the bi-propellants. Consequently LiNO3 could be an appropriate additive for the reduction of the ignition delay times of DMAZ-WFNA and DMAZ-IRFNA bi-propellants.

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Investigation of glycerol doping on ignition delay times and laminar burning velocities of gasoline and diesel fuel

Jach A., Cieślak I., Teodorczyk A.

Combustion Engines

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2017

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R. 56, nr 2

167--175

EN

Glycerol is a major by-product of biodiesel production. Per one tone of produced biodiesel, one hundred kilograms of glycerol is produced. Production of glycerol is increasing due to increase of demand for biodiesel. One of methods of glycerol utilization is combustion. Recent experimental studies with use of a diesel engine and a constant volume combustion chamber show that utilization of glycerol as a fuel results in lower NOx emissions in exhaust gases. It combusts slower than light fuel oil, what is explained by higher viscosity and density of glycerol. Glycerol has low cetane number, so to make combustion in a diesel engine possible at least one of the following conditions need to be fulfilled: a pilot injection, high temperature or high compression ratio. The aim of the paper is to compare glycerol to diesel and to assess influence of glycerol doping on gasoline and diesel fuel in dependence of pressure, temperature and equivalence ratio. The subject of this study is analysis of basic properties of flammable mixtures, such as ignition delay times and laminar burning velocities of primary reference fuels (diesel: n-heptane and gasoline: iso-octane). Calculations are performed with use of Cantera tool in Matlab and Python environments. Analyses of influence of glycerol on ignition delay times of n-heptane/air and iso-octane/air mixtures covered wide range of conditions: temperatures from 600 to 1600 K, pressure 10-200 bar, equivalence ratio 0.3 to 14, molar fraction of glycerol in fuel 0-1 in air. Simulations of LBV in air cover temperatures: 300 K and 500 K, pressures: 10, 40, 100, 200 bar and equivalence ratio from 0.3 to 1.9. Physicochemical properties of gasoline, diesel and glycerol are compared.

4

The Influence of Flame Retardant on the Ignitability of Wood Determined by Cone Calorimeter Method

Helwig M., Wolański P.

Archivum Combustionis

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2002

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Vol. 22 nr 3-4

173-186