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Using sensitivity analysis and gradual evaluation of ignition delay error to produce accurate low-cost skeletal mechanisms for oxidation of hydrocarbon fuels under high-temperature conditions

Shakeri, A ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1021/acs.energyfuels.7b01671
  3. Abstract:
  4. Three-dimensional thermo-hydrodynamic analysis of gas turbine combustion chambers is of great importance in the power generation industry to achieve higher efficiency and reduced emissions. However, it is prohibitive to use a comprehensive full-detailed mechanism in their simulation algorithms because of the huge CPU time and memory space requirements. Many reduction approaches are available in the literature to remedy this problem. Here a new approach is presented to reduce large detailed or skeletal mechanisms of oxidation of hydrocarbon fuels to a low-cost skeletal mechanism. The method involves an integrated procedure including a Sensitivity Analysis (SA) and a procedure of Gradual Evaluation of Ignition Error (GEIE). The sensitivity analysis identifies reactions which have less effect on the flame temperature (Tf) and also those with less effect on the NO concentration (XNO). Using the GEIE procedure also identifies reactions that have less effect on the ignition delay time (τign). In this process, three cutoff limits are selected for Tf, XNO, and τign. The procedure is validated and examined for two different hydrocarbon fuels, i.e., methane and kerosene. The detailed mechanism of GRI-3.0 is used for methane, to produce a low-cost skeletal mechanism containing 118 reactions and 39 species. Similarly, a validated skeletal mechanism for kerosene including 382 reactions and 106 species is used to generate a low-cost skeletal mechanism including only 180 reactions and 79 species. The accuracy of the obtained skeletal mechanisms was investigated to predict the ignition delay and the flame temperature for ranges of inlet temperatures (T0) of 1000-1800 K, combustion pressures (pc) of 1.0-30.0 atm, and equivalence ratios (φ) of 0.5-2.0 using a homogeneous IGNITION model. In addition, the applicability of the produced mechanisms to predict oxidation parameters such as flame temperature, velocity of burnt gas, concentration of the main fuel species, some minor radicals, and other selected species was investigated and validated for both skeletal mechanisms using homogeneous models PSR and PREMIXED over a range of different T0 (300-1800 K), pc (1.0-30.0 atm), and φ values (0.5-2.0). Comparisons show that the two new skeletal mechanisms have a good agreement with similar known base mechanisms but offer a significant gain in terms of computational cost. © 2017 American Chemical Society
  5. Keywords:
  6. Combustion chambers ; Cost benefit analysis ; Costs ; Fuels ; Gas emissions ; Gas turbines ; Hydrocarbons ; Kerosene ; Methane ; Musculoskeletal system ; Oxidation ; Sensitivity analysis ; Combustion pressure ; Computational costs ; Gas-turbine combustion ; High temperature condition ; Oxidation parameters ; Power generation industries ; Simulation algorithms ; Thermo-hydrodynamic analysis ; Ignition
  7. Source: Energy and Fuels ; Volume 31, Issue 10 , 2017 , Pages 11234-11252 ; 08870624 (ISSN)
  8. URL: https://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.7b01671