Modeling the combustion of high molecular weight fuels by a functional group approach

Abstract

Modeling the combustion behavior of real fuels is a challenging task: Significant analytical efforts are required to characterize the fuel composition, and comprehensive kinetic models are necessary to reproduce the behavior of the different fuel components. Both these aspects become increasingly critical for fuels having a high molecular weight, wherein both the characterization of the single components and the kinetics involved in their oxidation become extremely complex. Indeed, kinetic models for large hydrocarbons can include thousands of species and tens of thousands of reactions. For these reasons, only a limited number of representative components are generally included in the simulations and these large kinetic mechanisms are reduced to simulate the behavior of real fuels in practical conditions. We propose a novel approach to the simulation of the combustion of high molecular weight fuels, wherein the fuel surrogate is defined in terms of pseudospecies including the functional groups contained in the actual fuel. These pseudocomponents, representing linear, branched, aromatic, saturated, and unsaturated structures, can undergo the typical reactions responsible for the low-temperature ignition of hydrocarbon as well as the interactions occurring in fuel blends. The basics of this concept will be presented, through application to linear and branched alkanes, and the potential of this approach is assessed by means of comparisons with experimental data and detailed kinetic simulations. The potential of this methodology for reducing computational expense in computational fluid dynamics simulations is also highlighted. C

A minimalist functional group (MFG) approach for surrogate fuel formulation

“…Yang et al [38] used the basic compositional data of jet fuels to predict the TSI in gas turbine combustors. Mehl et al [56] defined fuel surrogates for high molecular weight compounds by using pseudo components that contain the functional groups present in the target fuel. The functional group based lumping techniques employed by Ranzi et al [57,58] at the CRECK modeling group in POLIMI replaced the long polymer chains with monomer pseudo species that participate in different reactions like initiation and abstraction.…”

Establishment and Validation of a Two-Component Surrogate Fuel Chemical Kinetic Skeletal Model for Fischer–Tropsch Fuel Synthesized from Coal

“…Mehl et al [28] stated that the low prediction value of CO2 concentration may be due to the lack of the description of partial oxidation products in the mechanism, with the same problem existing in the present mechanism.…”

“…Meanwhile, the concentration of C 2 H 2 is overestimated from 750 to 1000K, but the overall predictions are still reasonable. Westbrook et al [12], Mze-Ahmed et al [27] and Mehl et al [28] also found that the predicted value of CO2 concentration was low at low temperatures when using a detailed mechanism to predict the oxidation behavior of hydrocarbon fuels. Pitz and Mueller [26] revealed that the species histories are extremely important in the validation of a chemical kinetic mechanism for surrogate fuels.…”

“…The laminar flame propagation velocity is one of the important parameters that is indicative of fuel combustion characteristics; it is solved by the premixed laminar flame-speed calculation reactor Mehl et al [28] stated that the low prediction value of CO2 concentration may be due to the lack of the description of partial oxidation products in the mechanism, with the same problem existing in the present mechanism.…”

Synthesis and Preliminary Characterization of a PPE-Type Polymer Containing Substituted Fullerenes and Transition Metal Ligation Sites

“…Hence, the polymer portions associated with the PPE backbone may interact with the media, but the fullerene portion is effectively ignored. While several researchers have successfully utilized GPC for fullerene-containing polymers without issue [27,43,44], many of these systems have significantly more limited fullerene loading than our structures. However, other groups [ 26,45] have reported large disparities between their GPC results and independent molecular weight determinations for the same reason described above.…”