Effects of Atomization Condition on Flame Structure and Emission Characteristics of Burning Rich-Premixed Spray Jets

2007 ◽  
Author(s):  
Nobutoshi Nakachi ◽  
Masato Mikami ◽  
Naoya Kojima
Keyword(s):  
Equivalence Ratio ◽  
Droplet Diameter ◽  
Flame Structure ◽  
Flame Height ◽  
Exhaust Emission ◽  
Emission Characteristics ◽  
Combustion Modes ◽  
Atomization Condition ◽  
Emission Index ◽  
Blue Flame

Flame structure and emission characteristics of burning premixed spray were experimentally studied for different atomization conditions. Two combustion modes with and without an internal flame were observed. As Sauter mean droplet diameter became larger than a specific value, the internal flame appeared inside the external group flame. The existence of the internal flame was affected by the equivalence ratio of premixed spray jet, too. As Sauter mean droplet diameter was increased, the average flame height increased but the average blue-flame height decreased. These tendencies were same for different equivalence ratios of premixed spray jet. As the equivalence ratio of premixed spray jet was increased, the average flame height increased but the average blue-flame height did not vary very much. Exhaust emission characteristics were also affected both by Sauter mean droplet diameter and the equivalence ratio of premixed spray jet. As Sauter mean droplet diameter was increased, the emission index of CO (EICO) increased. EINO took maximum at Sauter mean droplet diameter of about 60 μm ∼ 80 μm. These tendencies in terms of Sauter mean droplet diameter were same for different equivalence ratios of premixed spray jet. EICO concentration showed low values without the internal flame.

Effects of Equivalence Ratio on the Emission and Temperature Characteristics of Spray Flames of Jet A/Butanol Blends Under Lean Conditions

2012 ◽  
Author(s):  
Tanjir H. Ratul ◽  
Ramkumar N. Parthasarathy ◽  
Subramanyam R. Gollahalli
Keyword(s):  
Equivalence Ratio ◽  
Flame Temperature ◽  
Nox Emission ◽  
Flame Height ◽  
Temperature Characteristics ◽  
Global Emission ◽  
Spray Flames ◽  
Index Level ◽  
Petroleum Fuels ◽  
Emission Index

Butanol is an attractive alternate fuel because it can be produced from renewable sources and has properties similar to those of petroleum fuels. Thus, blending butanol with petroleum fuels is a promising solution to reduce the dependence on petroleum fuels. In a previous study, we investigated the differences in the structure and emissions of Jet A and Butanol flames. The objective of this investigation was to study the emission and in-flame temperature characteristics of spray flames of Jet A/butanol blends at two equivalence ratios: 0.75 and 0.95. In addition to pure Jet A and pure butanol, blends of Jet A with 25%, 50% and 75% volumetric concentrations of butanol were used as fuel. The liquid fuel was atomized and combusted with air in a heated environment (479 K). The equivalence ratio was changed by altering the fuel flow rate, while maintaining the atomizing and coflow air flow rates constant, thus maintaining gas velocity field invariant. The global emission index of CO varied non-monotonically with the volume concentration of butanol in the blend at the lower equivalence ratio whereas the variation was gradual at the higher equivalence ratio. The global NOx emission index decreased monotonically as the butnaol content was increased at both equivalence ratios. The global NOx emission index level in the flames at equivalence ratio of 0.95 was higher than that at equivalence ratio of 0.75. At 25% flame height, the peak reaction zone was located off-axis; this radial location moved further away from the centerline as the equivalence ratio was increased. The peak temperatures were comparable in all the flames. The flames with butanol highlighted the effects of preferential vaporization of butanol.

scholarly journals Emission Characteristics for Swirl Methane–Air Premixed Flames with Ammonia Addition

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 662
Author(s):  
Joanna Jójka ◽  
Rafał Ślefarski
Keyword(s):  
Equivalence Ratio ◽  
Combustion Process ◽  
Great Influence ◽  
Emission Characteristics ◽  
Firing Rates ◽  
Numerical Tests ◽  
Ammonia Addition ◽  
Swirl Flame ◽  
Reactor Network ◽  
No Emissions

This paper details the experimental and numerical analysis of a combustion process for atmospheric swirl burners using methane with added ammonia as fuel. The research was carried out for lean methane–air mixtures, which were doped with ammonia up to 5% and preheated up to 473 K. A flow with internal recirculation was induced by burners with different outflow angles from swirling blades, 30° and 50°, where tested equivalence ratio was 0.71. The NO and CO distribution profiles on specified axial positions of the combustor and the overall emission levels at the combustor outlet were measured and compared to a modelled outcome. The highest values of the NO emissions were collected for 5% NH3 and 50° (1950 ppmv), while a reduction to 1585 ppmv was observed at 30°. The doubling of the firing rates from 15 kW up to 30 kW did not have any great influence on the overall emissions. The emission trend lines were not proportional to the raising share of the ammonia in the fuel. 3D numerical tests and a kinetic study with a reactor network showed that the NO outlet concentration for swirl flame depended on the recirculation ratio, residence time, wall temperature, and the mechanism used. Those parameters need to be carefully defined in order to get highly accurate NO predictions—both for 3D simulations and simplified reactor-based models.

Sign in / Sign up

Export Citation Format

Share Document