Combustion of n-heptane with steam injection in a laboratory spray burner
I.S. Anufriev1,2, E.P. Kopiev1, I.S. Sadkin1,2, M.A. Mukhina1, A.V. Minakov1, V.A. Kuznetsov1
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: burner, superheated steam, n-heptane, diesel fuel, regime control, NO
Abstract
This work is a continuation of a cycle of research by the authors aimed at studying the laws of liquid hydrocarbon combustion under steam supply conditions as applied to the development of low-emission burners. When simulating numerically diesel fuel combustion, n-heptane (formula C7H16) is used as a one-component analogue. Reliable experimental data are required to verify the obtained results. In this work, for the first time, the combustion parameters of n-heptane are experimentally studied when it is sprayed with superheated steam in a new laboratory atmospheric burner with forced air supply to the gas generation chamber. The calculation results are compared with data on diesel fuel. The performed comparison shows that the characters of gas component dependences inside the flame for diesel and heptane differ. This is primarily due to the different densities, viscosities of fuels, their flammability and burning rate (depending, among other things, on the forced supply of air (oxidizer)). At that, a quantitative comparison shows that the values of gas components at the flame boundary are quite close to each other. The effect of ongoing physicochemical processes in the presence of steam (gasification, hydrocarbon splitting, combustible mixture dilution, formation of active OH radicals) on the composition of final combustion products is higher than the effect of fuel properties. It is shown that during the combustion of n-heptane atomized by a steam jet, all the main features characteristic of diesel combustion with steam supply are retained. High completeness of fuel combustion and low level of toxic emissions into the atmosphere are ensured, which satisfies the European standard EN:267. With an increase in the share of steam in the combustible mixture, the tendency to a CO and NOx decrease remains. The air flow control in the gas generation chamber of the burner allows further regulation of the level of toxic combustion products released into the atmosphere. The dynamics of dependences of CO and NOx emissions repeats for heptane and diesel with some local differences. Also, the paper analyzes the correctness of n-heptane applicability for the problems of numerical simulation of diesel combustion in a steam jet with the indicated assumptions.
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