Simulation of microalgae oil spray characteristics for mechanical fuel injection and CRDI systems

A possibility of obtaining the micro- and macroparameters of a microalgae oil spray very similar to that of a diesel fuel as well as of ensuring the good level of their correspondence within a wide range of injection pressures distinct from mechanical fuel injection systems (800–1400 bar) and common rail direct injection systems (2000–2500 bar) will definitely lead to the fact that microalgae oil is at or very near commercialization. In this study, mathematical equations proposed by Lyshevsky and later approved by Razleytcev and Kuleshov were further rearranged to obtain dimensionless parameters capable of characterizing the variation of the integral liquid “core” length of a microalgae oil spray, the integral Sauter mean diameter, and the integral spray cone half-angle tangent for a broad range of injection pressures and preheating temperatures. At high fuel injection pressures and ambient temperature, the evolution of microalgae oil spray was completely different from the baseline mineral diesel, suggesting its far worse fuel atomization with a 41–49% larger droplet size distribution, a 40–58% narrower spray cone angle, and a 307–419% longer distance from the exit of the nozzle to the break-up point. We propose a method that allows variations in relational expressions of the spray-describing variables to be considered as part of the injection process capability study. A temperature interval of 105–115°C was found to ensure the correspondence of micro- and macroparameters of the microalgae oil spray vis-a-vis diesel fuel spray (20 °C) with a high level of precision (r = 0.91–1.0) for both the MFI and CRDI systems.