Effects of TRiEGME on water icing behavior in aviation turbine fuel

Abstract

The high vapor pressure of diethylene glycol monomethyl ether, the only approved civil aviation fuel system icing inhibitor (FSII), causes the peeling of fuel tank topcoat material. This leads to increased maintenance costs and decreased aircraft mission capabilities. Triethylene glycol monomethyl ether (TriEGME) has been proposed as a potential replacement as it has a low vapor pressure and can partition into any free water in the fuel forming a solution with a low freezing point. However, its use has not been approved by airworthiness authority because very few data are available for its impacts on water solubility and icing behavior in fuel. The effects of TriEGME on water solubility, solidification temperature, and water icing behavior in fuel were thoroughly studied. At added concentration ranging from 0.10 to 0.15 vol. % water solubility in jet fuel almost tripled compared with that without FSII. The solidification temperatures for water in fuel with FSII and for mixture of water and FSII decreased with increased FSII concentration. Moreover, partition coefficient, defined as equilibrium FSII concentration in aqueous phase divided by equilibrium FSII concentration in fuel phase, decreased with increased FSII concentration in fuel. At equilibrium condition with fixed FSII concentration in fuel, decrease in fuel temperature led to an increase in partition coefficient. An estimation of required dosage for TriEGME to prevent water icing in fuel can be achieved by comparison of TriEGME concentration in aqueous phase with its corresponding freezing temperature.