Thermal stability control of the water-in-diesel microemulsion fuel produced by using a nonionic surfactant combined with aliphatic alcohols

Abstract

One of the central challenges in producing water-in-diesel microemulsion fuels is to attain their thermal stability (to separate phases) for possible utilization and storage in various environmental and operating conditions. Thus, it should be possible to control the stability of the microemulsion systems at different temperatures. The present study discusses how to control the thermal stability of the microemulsion fuels in a temperature range from −21 °С to +73 °С. The effects of various alcohols, the concentration of ammonium acetate, and the surfactant/co-surfactant and diesel/water ratios are examined. Various C₅-C₉ alcohols can be used as co-surfactants to stabilize the microemulsions. An increase in the co-surfactant content and the usage of ammonium acetate brines as dispersed phase shifts the ranges of the thermal stability of the water-in-diesel microemulsion fuel towards lower temperatures. A decrease of the water fraction in the microemulsion fuel by 30% contributes to more than two-fold widening of the temperature band of stability. The optimum composition of the microemulsion fuel with the temperature bandwidth of thermal stability of about 86 °С is formulated. The thermal stability of the water–diesel–Neonol AF 9-6–2-ethylhexanol microemulsion system are compared with the known counterparts.

Graphical Abstract

Keywords:

• Water-in-diesel microemulsion
• alternative fuel
• fish diagram
• nonionic surfactant
• aliphatic alcohol

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Russian Science Foundation under Grant [18-73-00083].