Biofuels have been arisen in the last decades as a new source of energy both because of the possible production all over the world and for their intrinsic capability to be a renewable source of carbon. The most used biofuels are biodiesel and bioethanol. Ethanol has been studied under several combustion conditions. It has been found that its use reduces or promotes the amount of the formed particulate depending on the combustion configuration. In diffusion flames, for example, the addition of a small amount of ethanol to the fuel increases particle formation. Vice versa, in premixed flames with different equivalent ratios a decrease in the particulate matter is obtained. This latter configuration has been investigated just for very fuel-rich conditions, whereas there is a lack of experimental data for flames near the soot threshold. The aim of this work is to study the effect of the equivalent ratio near the soot threshold when different amount of ethanol are added to the fuel. Ethylene laminar premixed flames with equivalent ratios ranging from 2.01 to 2.31 have been studied varying the ethanol amount from 0 to 30%. The flames were stabilized with a stainless steel plate on a capillary burner with a cold gas velocity of 10 cm/s. To avoid condensation and keeping constant the temperature in all the investigated conditions, recirculating water in the burner was fixed at 75°C. Premixed gases were preheated at 150°C and sent to the burner. The ethanol was supplied by a New Era syringe pump that allows having high repeatability of the measurements with stable and constant flow rate. The measure of nanoparticle and soot was made by laser induced fluorescence (LIF) and laser induce incandescence (LII), respectively. The laser light source was the fourth harmonic of a Nd:YAG pulsed laser, i.e. at 266 nm. The LIE signal was measured with an ICCD camera 90 deg to the incident excitation light. In the investigated conditions, the lower is the equivalent ratio the higher is the reduction of total particulate matter. Moreover wavelength peaks of emission signal did not change when ethanol was added. This means that particles produced with and without ethanol are quite similar. Hence, the effect of ethanol in the flame is probably related to the effect on the flame front through its decomposition, rather than to a change in the growth process of the particles in flame.
ADDITION OF ETHANOL IN RICH PREMIXED FLAMES OF ETHYLENE: THE EFFECT OF THE EQUIVALENCE RATIO
M Commodo;P Minutolo;
2011
Abstract
Biofuels have been arisen in the last decades as a new source of energy both because of the possible production all over the world and for their intrinsic capability to be a renewable source of carbon. The most used biofuels are biodiesel and bioethanol. Ethanol has been studied under several combustion conditions. It has been found that its use reduces or promotes the amount of the formed particulate depending on the combustion configuration. In diffusion flames, for example, the addition of a small amount of ethanol to the fuel increases particle formation. Vice versa, in premixed flames with different equivalent ratios a decrease in the particulate matter is obtained. This latter configuration has been investigated just for very fuel-rich conditions, whereas there is a lack of experimental data for flames near the soot threshold. The aim of this work is to study the effect of the equivalent ratio near the soot threshold when different amount of ethanol are added to the fuel. Ethylene laminar premixed flames with equivalent ratios ranging from 2.01 to 2.31 have been studied varying the ethanol amount from 0 to 30%. The flames were stabilized with a stainless steel plate on a capillary burner with a cold gas velocity of 10 cm/s. To avoid condensation and keeping constant the temperature in all the investigated conditions, recirculating water in the burner was fixed at 75°C. Premixed gases were preheated at 150°C and sent to the burner. The ethanol was supplied by a New Era syringe pump that allows having high repeatability of the measurements with stable and constant flow rate. The measure of nanoparticle and soot was made by laser induced fluorescence (LIF) and laser induce incandescence (LII), respectively. The laser light source was the fourth harmonic of a Nd:YAG pulsed laser, i.e. at 266 nm. The LIE signal was measured with an ICCD camera 90 deg to the incident excitation light. In the investigated conditions, the lower is the equivalent ratio the higher is the reduction of total particulate matter. Moreover wavelength peaks of emission signal did not change when ethanol was added. This means that particles produced with and without ethanol are quite similar. Hence, the effect of ethanol in the flame is probably related to the effect on the flame front through its decomposition, rather than to a change in the growth process of the particles in flame.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
