Experimental investigation of the effects of air swirling and fuel mixtures on emission characteristics of a cylindrical furnace

In this research, experimental investigation was undertaken to find the effects of air swirling on pollutant emissions in a cylindrical combustion chamber fuelled with diesel-biodiesel-ethanol blends. At the first, a burner system with various radial air swirl generator (the vane angles were 15°, 25°, 35°, 45°, 60° and 90°) attached to the combustion chamber of 400 mm inside diameter and 2000 mm length. Fuel blends were D100, D85B10E5 (85% diesel, 10% biodiesel and 5% Ethanol on a volume basis), D80B10E10, D75B20E5, and D70B25E5. Biodiesel fuel was produced from waste cooking oil and ethanol as a renewable fuel was made from corn and other plant materials. CO, CO2 and NOx as the emission characteristics were determined in this research. According to the results the minimum CO emission belongs to fuel blend for D70B25E5 and air swirl generator with the vane angles of 15° and the maximum CO emission happens for net diesel (D100) and air swirl generator with the vane angles of 90°. Moreover, fuel blend D80B10E10 has the maximum CO2 emission. It shows that ethanol can more effective to increase in CO2 values than that of biodiesel. Besides, the minimum CO2 emission obtained for fuel blend D100. However the results showed that vane angle has not significant effect on CO2 emission. About NOx emission, the minimum value occurs for D100 and air swirl generator with the vane angles of 45°. In addition, air swirling condition with higher vane angles of 45° leads to higher premixed combustion and temperature and causes an increase in NOx emission. Also the maximum value of NOx emission will be for D70B25E5 because of higher biodiesel content as an oxygenated fuel. Higher NOx formation occurred in using biodiesel due to the presence of the chemically bound oxygen content in the biodiesels. On the other hand, NOx value of ethanol included fuel blends is higher than that of net diesel (D100) because of that the cetane number reduced by the addition of ethanol and the condition leads to higher premixed combustion and ignition delay and then NOx increase.