Compression ignition engine modifications for straight plant oil fueling in remote contexts: Modification design and short-run testing

Abstract

Though many plant oils have a similar energy density to fossil diesel fuel, several properties of plant oils are considerably different from those of diesel. Engine modifications can overcome some of these differences. An engine modification kit has been designed and tested for a slow speed, stationary, indirect-injection diesel engine – the Lister-type CS 6/1, common throughout the developing world. The kit allows waste vegetable oil fueling with similar performance to that of diesel fueling. The kit’s simple yet robust design is targeted for use as a development mechanism, allowing remote farmers to use locally grown plant oils as a diesel substitute. The modification kit includes a preheating system and the tuning of the injector pressure and timing to better atomize given the unique properties of straight plant oils. The design methodology for the modifications is detailed and a suite of performance test results are described including fuel consumption, efficiency, pre-combustion chamber pressure, and various emissions. The results of the study show how a combination of preheating the high pressure fuel line, advancing the injector timing and increasing the injector valve opening pressure allows this engine to efficiently utilize plant oils as a diesel fuel substitute, potentially aiding remote rural farmers with a lower cost, sustainable fuel source – enabling important agro-processing mechanization in parts of the world that needs it most.