Effect of Alcohol Carbon Chain on Enthalpy of Combustion and Ignition Delay Time for Gelled Hypergolic Propellant System

Abstract

Study conducted for this paper was to understand the effect on a) enthalpy of combustion and b) ignition delay for gelled hypergolic propellants for the alcohol family, when carbon chain length is varied from ethanol to heptanol. Gel propellant formulated from the alcohol family, ethanol to heptanol, using organic gel with least weight percent added was 2 wt% by weight of the gelling agent. It was observed that the enthalpy of combustion of only pure ethanol gel fuel shows a marked increase in energy with respect to pure liquid and metalized gelled ethanol. Whereas, in the case of other alcohol fuel from propanol to heptanol, the enthalpy of combustion of both gel and metalized gel case is lower with respect to their respective liquid state. Hypergolicity of the formulated gel propellant were achieved using two catalyst CCAT (Copper (II) chloride) and MCAT (Manganese (II) acetylacetonate) with Hydrogen Peroxide (Purity>90 %). The ignition delay time of the formulated gel system with hydrogen peroxide in the presence of catalyst was also investigated and it was observed that the ignition delay time of the all the investigated gels (both pure and metalized) were lower with MCAT with respect to CCAT. The delay time increases for both the catalysts with formulated gel alcohol fuel with increasing carbon chain. At the same time with increase in carbon chain and decrease in vapor density of the fuel, the respective investigated fuel in liquid phase were not hypergolic in the presence of MCAT and CCAT catalyst except for propanol and butanol, which showed hypergolicity only with CCAT.