Effects of blending a heavy alcohol (C_(20)H_(40)O with diesel in a heavy-duty compression-ignition engine

摘要

There is an extensive worldwide search for alternate fuels that can displace fossil-based resources, yet still fit within existing infrastructure. At Argonne National Laboratory, strains of fuel have been designed that are generated by photosynthetic bacteria, eventually producing a heavy alcohol called phytol (C_(20)H_(40)O). Phytol's physical and chemical properties (cetane number, heat of combustion, heat of vaporization, density, surface tension, etc.) correspond in magnitude to those of diesel fuel, suggesting that phytol might be a good blending agent in compression ignition (CI) engine applications. The main objective of this study is to investigate the feasibility of using phytol as a blending agent with diesel. Three phytol-diesel blends were chosen for evaluation: P5, P10, and P20 (5%, 10%, and 20% phytol by volume). The fuel blends were extensively analyzed to determine their chemical and physical properties, with mostly comparable values, excepting viscosity and vapor pressure. In order to understand the effects of higher viscosity phytol in the fuel injector, three-dimensional simulations of transient, turbulent nozzle flow compared the injection and cavitation characteristics of the various blends. Specifically, area and discharge coefficients and mass flow rates of diesel and phytol blends were compared under corresponding engine operating conditions. Experimental research was performed using a single-cylinder engine under conventional operating conditions to gather comparative performance and emissions characteristics of the various blends of phytol and diesel. The influence of the fuel's chemical composition on performance and emission characteristics was captured by executing an injection timing sweep. Combustion characteristics such as the in-cylinder pressure trace were comparable for the diesel and all the blends with phytol at each of the injection timings. The diesel/phytol blends show similar emissions characteristics as the diesel. The combustion event was depicted by performing high-speed, natural luminosity endoscopic imaging. The conclusion is that phytol may be a suitable blending agent with diesel fuel for CI applications.