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Alternative fuels providing diesel engine emission reductions are developed in order to provide practical solutions to environmental problems in different areas of the world. Diesel fuel emulsions containing water, considered as alternative fuels, have shown their potential to help reaching simultaneous reduction of NOx and PM exhaust emissions. In this study, diesel fuel microemulsions have been developed and optimized considering their cost-effectiveness. Water is incorporated into the fuel in the form of micelle structures, mostly using naturally derived surfactants. The finished fuel is visually transparent and thermodynamically stable over a wide range of storage and handling conditions. Experimental work was conducted to explore the impact of water in diesel fuel microemulsions on CIDI engine performance, regulated and non-regulated exhaust emissions.

Six commercial different additive packages to be used in the Venezuelan Internal Market Diesel formulations were evaluated in terms of their performance in corrosion inhibition, oxidation stability, injector cleanliness and emissions, as well as fuel economy improvement. Laboratory, field and bench tests were carried out. In laboratory tests, additives evaluated were added to four Venezuelan Diesel fuel formulations at the recommended supplier doses: corrosion (ASTM D665), oxidation stability (ASTM D2274), emulsification (ASTM D1094). Also, physicochemical properties required by Venezuelan Diesel fuel specifications were evaluated. Three different trucks (per additive) were run in fleet tests in order to determine injector cleanliness performance. Truck injector flow was measured in every injector, according to ISO 4010 procedure, before and after 5000-6000 km field accumulations. Two trucks were run without additive dosification, and were used for base line comparison.

Fuel reformulation represents a major approach to reduce emissions in the current fleet. In this work, a medium-duty engine was used to determine the potential benefits of using reformulated Diesel fuel with controlled composition. This particular engine technology is used approximately in more than 60% of the corresponding transport fleet. The fuel properties that received special attention were sulfur content (390 - 8670 ppm), aromatic content (9.8 - 32.6 wt %), cetane number (40 - 51.6) and distillation temperature for 90 % volume recovered T90 (307 - 350 °C). Testing was conducted on the engine installed on a test bench and operated on a 4-mode cycle with two speeds and medium to high load. Data was taken on each mode and statistical procedures for averaging, weighting and analyzing, were applied to study engine operation. Combustion performance was observed based on a heat release analysis, comparing burning rates and ignition delay.