Effects of dimethyl ether on n-butane oxidation

Abstract

h i g h l i g h t s" Effects of DME addition to n-butane oxidation were studied. " DME was found to decrease the formations of CO, aromatic species and PAHs. " DME addition increased the formations of formaldehyde and acetaldehyde. " Effects of equivalence ratio were investigated in fuel-rich conditions. " Increasing equivalence ratio increased the formations of aromatic and PAH species. a r t i c l e i n f o t r a c tDimethyl ether (DME) is the simplest ether and it is used as an alternative fuel or fuel additive to reduce toxic emissions from combustion processes. The effects of DME on n-butane oxidation were investigated for two different concentrations of DME in the fuel mixture (i.e., 20% and 50%) and two different fuel-rich equivalence ratios (i.e., 2.6 and 3.0) using detailed chemical kinetic modeling. Reactor model was selected as atmospheric-pressure, adiabatic, tubular reactor, operated under laminar flow conditions. The concentration profiles of major, minor, and trace species were obtained for n-butane/DME/oxygen/argon at six different reactor inlet temperatures, and the results were compared with those attained for pure n-butane oxidation case (n-butane/oxygen/argon). Dimethyl ether addition decreased formations of various toxic species such as carbon monoxide, aromatic species, and polycyclic aromatic hydrocarbons, while it increased the formations of formaldehyde and acetaldehyde. Increasing equivalence ratio increased the formations of carbon monoxide, methane, aromatic species, and polycyclic aromatic hydrocarbons, while its effects on formaldehyde and acetaldehyde were not pronounced under the conditions studied.

Effects of reactor pressure and inlet temperature on n‐butane/dimethyl ether oxidation and the formation pathways of the aromatic species

“…The higher reactor pressure (5 atm) decreased the mole fractions of C 2 H 2 (Figure a), C 3 H 3 (Figure b), and C 4 H 2 (Figure a), while increasing the mole fractions of C 4 H 4 (Figure b) and c‐C 5 H 6 (Figure c). DME was shown to decrease the formations of these precursor species in our previous study . In this study, this decreasing effect seemed to be more dominant at the higher pressure.…”

“…. The results of this comparison were described in our previous work . The mole fraction profiles of n ‐C 4 H 10 , CO, CO 2 , and C 2 H 4 were successfully reproduced with the detailed mechanism, with only CO 2 being slightly over predicted.…”

“… with the detailed mechanism developed at the same operating conditions, mole fraction profiles of CH 3 OCH 3 , O 2 , and CH 4 were successfully predicted, while CH 2 O (formaldehyde) mole fractions were slightly under predicted. The results of these comparisons were also presented in our previous work .…”

“…Using the same reactor specifications and process conditions employed pre-viously, mole fraction profiles of n-C 4 H 10 , CO, CO 2 , and C 2 H 4 (ethylene) were obtained with the detailed mechanism developed, and compared with the experimental data of Chakir et al [13]. The results of this comparison were described in our previous work [8]. The mole fraction profiles of n-C 4 H 10 , CO, CO 2 , and C 2 H 4 were successfully reproduced with the detailed mechanism, with only CO 2 being slightly over predicted.…”

“…In a previous work, we studied the oxidation of n‐butane/DME blend in a tubular reactor, for two different DME concentrations in the fuel mixture (20 and 50 mol %) and for two different equivalence ratios (2.6 and 3.0) at varying inlet temperatures . Concentrations of various toxic species, such as CO, aromatic species, and polycyclic aromatic hydrocarbons (PAHs) were found to decrease with increasing DME concentration.…”