Combustion Characteristics of a Non-Premixed Oxy-Flame Applying a Hybrid Filtered Eulerian Stochastic Field/Flamelet Progress Variable Approach

Abstract

The oxidation of methane under oxy-fuel combustion conditions with carbon capture is attractive and deserves huge interest towards reducing CO2 and NOx emissions. The current paper reports on the predictions and analysis of combustion characteristics of a turbulent oxy-methane non-premixed flame operating under highly diluted conditions of CO2 and H2 in oxidizer and fuel streams, respectively. These are achieved by applying a novel, well-designed numerical combustion model. The latter consists of a large eddy simulation (LES) extension of a recently suggested hybrid model in Reynolds averaging-based numerical simulation (RANS) context by the authors. It combines a transported joint scalar probability density function (T-PDF) following the Eulerian Stochastic Field methodology (ESF) on the one hand, and a flamelet progress variable (FPV) turbulent combustion model under consideration of detailed chemical reaction mechanism on the other hand. This novel hybrid ESF/FPV approach removes the weaknesses of the presumed-probability density function (P-PDF)-based FPV modeling, along with the solving of associated additional modeled transport equations while rendering the T-PDF computationally less affordable. First, the prediction capability of the LES hybrid ESF/FPV was appraised on the well-known air-piloted methane jet flame (Sandia Flame D). Then, it was assessed in analyzing the combustion properties of a non-premixed oxy-flame and in capturing the CO2 dilution effect on the oxy-fuel flame behavior. To this end, the so-called oxy-flame B3, already numerically investigated in a RANS context, was analyzed. Comparisons with experimental data in terms of temperature, scalar distributions, and scatter plots agree satisfactorily. Finally, the impact of generating the FPV chemistry table under condition of unity Lewis number, even with CO2 dilution, was investigated on the general prediction of the oxy-fuel flame structure, stability and emissions. In particular, it turns out that 68% molar percentage of CO2 leads to 0.39% of CO formation near the burner fuel nozzle and 0.62% at 10 dfuel above the nozzle.

Validation of an Eulerian Stochastic Fields Solver Coupled with Reaction–Diffusion Manifolds on LES of Methane/Air Non-premixed Flames

“…The radical OH is also better represented by this manifold. The unrealistic structures of temperature within 0.8 < f < 0.9 reported by Hinz (2000) and Mahmoud et al (2019) and attributed to the IEM model are not seen in this work, confirming the validity of the REDIM tabulation method when coupled with the ESF. Due to the low level of local extinction of flame D, the conditional fluctuations are expected to be small.…”

“…Since the target of this investigation is further reducing the computational cost required by the transport of the ESF based on a full chemistry state, the ESF transport equations were coupled with a reduced chemistry model. Recently, ESF solvers combined with pretabulated chemistry deriving from the FPV (Pierce and Monin 2004) or the FGM (Oijen and de Goey 1992) combustion models were proposed by several groups (Avdic et al 2017;Collonval 2015;Duan et al 2019;Kulkarni and Polifke 2013;Mahmoud et al 2019) for OpenFOAM applications. In this work, the ESF solver retrieves the thermo-chemical state from REDIM tables instead.…”

Analysis of Local Exergy Losses in Combustion Systems Using a Hybrid Filtered Eulerian Stochastic Field Coupled with Detailed Chemistry Tabulation: Cases of Flames D and E

“…In the present work, the mixture fraction, Z, introduced according to Bilger et al [33], and the progress variable, Y c , are considered as the controlling variables. The progress variable, Y c , is defined as [34]:…”

“…It was updated and applied in [15][16][17] to solve the evolution equation of the FDF for controlling variables. The transport equation for the filtered joint probability density function P(Ψ), also denoted as FDF, can be derived as [11,[15][16][17]34,[39][40][41]:…”

Sustainable Energy Systems: Optimization and Efficiency

“…A thermoeconomic modelling and parametric study of a simple orc, for the recovery of waste heat from a 2 MW gas engine under different working fluids, was presented in [19], and a parametric numerical study of the airflow and thermal performance of a real data center, for improving sustainability by reducing the thermal load [20]. The predictions and analysis of the combustion characteristics of a non-premixed oxy-flame, by applying a hybrid filtered Eulerian stochastic field/flamelet progress variable approach, was addressed in [21]. Comparisons with experimental data, in terms of temperature, scalar distributions and scatter plots, were made, and satisfactory results were obtained.…”