Evaluation of sooting tendency of different oxygenated and paraffinic fuels blended with diesel fuel

In this study a comparative experimental work about the sooting tendency of different fuel blends has been carried out. Three groups of alternative fuels, blended with diesel fuel, were tested: (1) an animal fat biodiesel; (2) two paraffinic fuels: a hydro-treated vegetable oil (HVO) and a gas-to-liquid (GTL) from natural gas and (3) two alcohols: ethanol and butanol. The smoke point of different binary alternative-diesel fuel blends was determined by means of a standardized Smoke Point Lamp. A low sulphur diesel fuel without biodiesel content was used as reference fuel. As sooting tendency parameters, both Threshold Sooting Index (TSI) and Oxygen Extended Sooting Index (OESI) from blends with respect to diesel fuel were compared. Two main trends were obtained. While biodiesel-, HVO- and GTL-diesel fuel blends showed similar exponential decreasing trend in sooting tendency as a function of blending percentage (with an exponential factor between -0.005 and -0.01), alcohol-diesel fuel blends resulted to be more effective suppressors of the soot (around 20 times better). Comparing the sooting tendency of fuel blends to engine opacity/particle emissions achieved by other authors, when great differences were obtained, as in the case of alcohol blends compared to biodiesel, HVO and GTL, the translation are in good agreement. (C) 2016 Elsevier Ltd. All rights reserved.