Variables Affecting NOx Formation in Lean-Premixed Combustion

Abstract

The formation of NOx in lean-premixed, high-intensity combustion is examined as a function of several of the relevant variables. The variables are the combustion temperature and pressure, fuel type, combustion zone residence time, mixture inlet temperature, reactor surface-to-volume ratio, and inlet jet size. The effects of these variables are examined by using jet-stirred reactors and chemical reactor modeling. The atmospheric pressure experiments have been completed and are fully reported. The results cover the combustion temperature range (measured) of 1500 to 1850 K, and include the following four fuels: methane, ethylene, propane, and carbon monoxide/hydrogen mixtures. The reactor residence time is varied from 1.7 to 7.4 ms, with most of the work done at 3.5 ms. The mixture inlet temperature is taken as 300 and 600 K, and two inlet jet sizes are used. Elevated pressure experiments are reported for pressures up to 7.1 atm for methane combustion at 4.0 ms with a mixture inlet temperature of 300 K. Experimental results are compared to chemical reactor modeling. This is accomplished by using a detailed chemical kinetic mechanism in a chemical reactor model, consisting of a perfectly stirred reactor (PSR) followed by a plug flow reactor (PFR). The methane results are also compared to several laboratory-scale and industrial-scale burners operated at simulated gas turbine engine conditions.

Combustor Stability and Emissions Research Using a Well Stirred Reactor

“…when z = 2.5 ms. Also, as seen in Fig. 10, our measured values of NO emissions were in close agreement with propane-air data of Steele et. al.…”

Ultrafast Heating in Nanosecond Discharges in Atmospheric Pressure Air

“…For the first positive system, a 600 grooves/mm grating and a longpass interference filter absorbing light for  < 420 nm were used. The emission of the N 2 (CB) (0,2) and (1,3) vibrational bands were recorded around 380 nm, and that of N 2 (BA) (3,0) to (11,8) between 610 and 710 nm. Absolute intensity calibration was done with a tungsten radiance standard (OL 550) keeping all parameters identical.…”

An Experimental Investigation on the NO and CO Emission Characteristics of a Swirl Convergent-Divergent Nozzle at Elevated Pressure

“…Nevertheless, when Rutar [13] studied NO x and CO emissions at an elevated pressure of 3.0-6.5 atm he concluded that NO x decreased a little with increasing pressure for a fixed residence time, which was also revealed by Steele et al [14]. Biagioli and Güthe [15] analyzed the NO from 1-30 bar based on a model, and they found that the NO x pressure exponent is negative under fully premixed conditions.…”

“…From Equation (14), one can clearly see the influence of P and ṁF/ṁpri on tg, tg decreased with an increase in P (P −0.43 ), but increased significantly with the increasing of ṁF/ṁpri ((ṁF/ṁpri) 2.07 ). A comparison of the measurement and prediction of tg with correlation Equation 14is presented in Figure 11.…”