Experimental Investigation on the Effect of Dilution and Air Stream Swirl on the NOx Emission in Premixed C3H8-Air Flame

Document Type : Research Article

Authors

Abstract

The reaction of thermal NO is highly sensitive to temperature and if a technique can reduce the flame temperature, it would be effective to reduce NOx formation. The dilution of the fuel and also producing swirling flows can reduce the flame temperature and as a result, decrease the rate of NOx formation. In the present study, the effect of dilution and the swirling flow on NOx emission in the premixed propane-air mixture is investigated experimentally. The experiments were carried out in an axially symmetric cylindrical furnace for an equivalence ratio of 0.7 to 1.3 and (0.0-1.0) dilution ratios. The swirling is achieved by a swirler with 45-degree angle corresponding to the swirl number of 0.7. The results show that by increasing the dilution ratio, the flame temperature and as the result, the NOx emissions are decreased. The results also reveal that the swirler causes better mixing of the fuel, air and the diluents and parts of combustion products are return to the reaction zone and since the present species have high heat capacities, they absorb the heat of combustion, which in turn decreases the temperature of the furnace and consequently decreases the NOx emissions. The experimental results are in a good agreement with the results reported by other researchers.

Keywords


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