Design and Characteristics of a New Pre-Evaporation Chamber Geometry for Low-Grade Palm Oil Fuel Evaporation for Micro Gas Turbine Application

Abstract

Recent increase in fuel prices, greenhouse emissions, global warming issue, as well as future predictions regarding fossil fuel depletion concerns have prompted widespread research on carbon-neutral renewable liquid biofuels as an alternative of petroleum fuels. In the present study, a numerical approach was used to design and optimize a novel design of pre-evaporation chamber, to pre-evaporate crude palm oil fuel using exhaust gas recycling to allow partially premixed fuel vapors to be introduced to the main combustion chamber. Discrete Phase Model (DPM) and species non-premixed model used in ANSYS-FLUENT software to simulate fuel evaporation. The pre-chamber optimization included the addition of variable number of revolve geometry to the walls to induce turbulence and to enhance the cyclonic motion caused by the tangential hot exhaust gas inlets with different fuel injection configurations. The number of revolves was varied in the range of 5-8 and diameter range of 40-90 mm with three injector configurations. The results revealed that the optimum chamber geometry consist of 7 revolves with 70 mm diameter with fuel evaporation rate about 0.0023kg/s and fuel evaporation percentage about 89%. Increasing the exhaust gas temperature from 950 °C up to 1050°C did not show a significant fuel evaporation enhancement. Results also showed that the evaporation enhancement is proportional to the number of fuel injectors where evaporation increased gradually from 73% to 89% when increasing number of injectors from 1 to 3.