Combustion Science and Technology, Vol.192, No.2, 240-259, 2020
Experimental Investigation of a Small-Scale Combustion Chamber Fuelled with Vegetable Oil
This study demonstrates the feasibility of employing high viscosity fuels such as vegetable oils in a premixed combustion configuration, applied to a small-scale combustion chamber. The main challenges to be solved are the poor atomization of vegetable oil, the issues in vaporizing the liquid droplets before combustion and the possible formation of solid deposits which may compromise the device, especially at small scale. For the purpose, a regenerative combustion chamber surrounded by two sets of helicoidal fins, acting as a recuperator, was developed and tested using vegetable oils as fuel. The regenerative combustion chamber has a diameter of 18 mm and the overall radial dimension, which includes two helicoidal channels surrounding the inner tube, is 32 mm. A sintered steel porous medium was placed in the combustion chamber to achieve flat flame. To guarantee good atomization of oil, a flow blurring injector was mounted on the combustion chamber. The combustion chamber was encased in insulating ceramic material to ensure adequate vaporization of fuel and it was tested under ambient pressure. The combustion chamber was able to run on vegetable oil with heat release rate ranging between 194 and 554 W for oil flow rates ranging between 0.35 and 0.875 ml/min. Results in terms of concentration of combustion products and axial distribution of temperature in the combustion chamber are presented, along with a visual observation of the flame. However, after a period of time operating exclusively using vegetable oil, clogging issues due to the formation of solid deposits upstream of the flame holder were encountered.