Thermodynamic criteria advantages

Microemulsions form spontaneously and exhibit nano-disperse structures. In contrast to emulsions there is no additional energy input necessary for the production of a microemulsion. The formation is thermodynamically favoured due to the ultra-low interfacial tension between the oil and water domains. The microemulsified fuels are in principle thermodynamically stable for an unlimited period of time only the chemical stability of the single components could be a limiting factor. A further advantage of microemulsions in contrast to emulsions is the fact that the water content can be adjusted over a broad range. Therefore, the combustion process can be customised to specific needs. An important criterion for a microemulsion to be used as fuel is that the one-phase region extends over a wide temperature range (Fig. 11.4). Mixtures of ionic and non-ionic surfactants, which exhibit almost temperature-invariant phase behaviour by optimal composition, are suitable to meet these standards. 

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