Effects of the Initial Gel Fuel Temperature on the Ignition Mechanism and Characteristics of Oil-Filled Cryogel Droplets in the High-Temperature Oxidizer Medium

Dmitrii O. Glushkov, Alexander G. Nigay, Vyacheslav A. Yanovsky, Olga S. Yashutina

Research output: Contribution to journalArticle

Abstract

The ignition mechanism was studied for a group of gel fuel compositions in a high-temperature oxidizer medium. It was determined how the initial temperature of the fuel influences the ignition characteristics. The gel fuel (oil-filled cryogel) was prepared from an oil emulsion based on the mixture of a combustible liquid and polyvinyl alcohol. The composition of primary oil emulsions was as follows: the aqueous solution of polyvinyl alcohol (5, 10 wt %) + 40-60 vol % of oil + 2 vol % of emulsifier. The initial temperature of gel fuels ranged from 188 to 293 K. Combustion was initiated in high-temperature motionless air at 873-1273 K. Using a high-speed video recording system, we established that at different initial temperatures of the gel fuel, a set of identical processes occurs during the induction period; these are different from the same physical and chemical processes during the ignition of a combustible liquid. After reaching threshold conditions, the flame spreads in the droplet's vicinity from a hot spot through the gas mixture. Hot spot is an ignited and a small-sized fragment separating and moving away from the molten fuel droplet as a result of a microexplosion. The values of the main process characteristic - ignition delay times - differ 25-95% for fuel samples with the initial temperature of 293 K and temperatures of 188-233 K because of a long heating and melting stage of the latter. This is explained by a 2.5-3.6-fold difference in the amount of energy, which is necessary to supply to a colder fuel sample for this phase transformation to occur, other things being equal.

Original languageEnglish
Pages (from-to)11812-11820
Number of pages9
JournalEnergy and Fuels
Volume33
Issue number11
DOIs
Publication statusPublished - 21 Nov 2019

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ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology

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