Publication: Development and optimization ofmicro gas turbine combustor fueled by refined palm oil
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Date
2024-03-01
Authors
Mohammed Raad, Abdulwahab
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Abstract
Investigations on alternative renewable liquid biofuels to replace petroleum oils have drastically increased in the past decades to mitigate the energy crisis and
global warming issues. In Malaysia, the abundance of liquid palm oil waste that can be used directly as fuel or converted into biodiesel (B100) to replace diesel fuel. However, these fuels suffer from high viscosity and lower heating value compared to diesel which presents a major challenge towards achieving clean and complete combustion. This research optimized a new combustion chamber alternative design for micro gas turbine (MGT) applications that can provide clean combustion of low-grade liquid biofuels without the need of fuel preheating or blending with fossil fuels. Chamber design optimization was performed in three stages Design of Experiment (DoE), while combustion and flow hydrodynamics were evaluated using CFD simulation in ANSYS-FLUENT program. Cold-flow spray atomization tests were experimentally performed for refined bleached deodorized palm oil (RBD), B100 and diesel, where spray pictures were analyzed using IC-measure software. RBD oil showed long liquid film extension before breaking down to large droplets resulting in low spray angle <10°, while B100 performed significantly better at lower flow. Increasing the flow increased the spray angle to 21°. The optimum combustion design was then fabricated and tested with Garrett GT-25 turbocharger in single stage MGT test rig. Modifications were then performed to optimize the MGT start-up process with RBD oil. Finally, MGT performance was characterized in the pressure range of 0.2-0.7 bar gauge pressure using RBD oil and palm biodiesel. The performance was compared to diesel as the benchmark fuel. The trend lines of turbine power against compressor pressure using diesel were similar to those of B100 and RBD oil at same pressure range. Minimum CO emission in the range of 132-135 ppm for diesel and B100 were achieved at the higher operating pressures, while RBD oil showed slightly higher value of 207 ppm. NOx emission showed comparable values in the range of 32-39 ppm for all the fuels. Finally, diesel suffered from its higher TIT value that reached 800°C at 0.7 bar compared to 785°C and 762°C for RBD oil and B100 respectively. Chamber efficiency was comparable for all fuel used with low values at low operation pressure and low flame intensity with the range about 85% to 92%. The CFD model was verified with experimental findings at 0.7 bar with low error of 1.6% for TIT, 2.6% for CO and 0.8% for NOx.