A computationally efficient, physics-based model for simulating heat loss during compression and the delay period in RCM experiments

Goldsborough, S. Scott; Banyon, Colin; Mittal, Gaurav

doi:10.1016/j.combustflame.2012.07.010

Cited by 38 publications

(19 citation statements)

References 58 publications

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“…The presence of the RCM crevice region could eventually influence the NTC behavior when multistage ignition occurs. The pressure rise due to the first stage ignition is reduced in experiments since a mass flow from the combustion chamber into the crevice occurs [46,47]. This effect should be quite small, but a worst-case estimation is made by forcing the simulation to follow a non-reactive pressure profile that completely suppresses the pressure increase due to first stage ignition.…”

Section: Rapid Compression Machine Ignitionmentioning

confidence: 99%

A comprehensive combustion chemistry study of 2,5-dimethylhexane

Sarathy

Javed

Karsenty

et al. 2014

Combustion and Flame

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Iso-paraffinic molecular structures larger than seven carbon atoms in chain length are commonly found in conventional petroleum, Fischer-Tropsch (FT), and other alternative hydrocarbon fuels, but little research has been done on their combustion behavior. Recent studies have focused on either mono-methylated alkanes and/or highly branched compounds (e.g., 2,2,4-trimethylpentane). In order to better understand the combustion characteristics of real fuels, this study presents new experimental data for the oxidation of 2,5-dimethylhexane under a wide variety of temperature, pressure, and equivalence ratio conditions. This new dataset includes jet stirred reactor speciation, shock tube ignition delay, and rapid compression machine ignition delay, which builds upon recently published data for counterflow flame ignition, extinction, and speciation profiles. The low and high temperature oxidation of 2,5-dimethylhexane has been modeled using a comprehensive chemical kinetic model developed using established reaction rate rules. The agreement between the model and data is presented, along with suggestions for improving model predictions. The importance of propene chemistry is highlighted as critical for correct prediction of high temperature ignition delay. The oxidation behavior of 2,5-dimethylhexane is also compared with oxidation behavior of other linear and branched octane isomers, in order to determine the effects of the number of methyl branches on combustion properties. Both experimental data and model predictions indicate that increasing the level of branching decreases fuel reactivity at low and intermediate temperatures. The model is used to elucidate the structural features and reaction pathways responsible for inhibiting the reactivity of 2,5-dimethylhexane. FUEL or CNF, Sarathy et al. submitted July 2013Introduction Detailed chemical kinetic models for transportation fuels have reached a level of fidelity where accurate predictions can be made of combustion phenomenon relevant to the operation of practical devices. Schofield [1] states that these large scale models are adequate as engineering tools for studying the combustion of new fuel molecules. A recent review paper by Pitz and Mueller [2] describing the development of diesel surrogate fuel models concluded that major research gaps remain in modeling high molecular weight (i.e., C 8 and greater) aromatics, alkyl aromatics, cyclo-alkanes, and lightly branched iso-alkanes. The present study is concerned with the combustion of branched alkanes, specifically 2,5-dimethylhexane, which has been reported as a component of petroleum combustion exhaust, smog, and tobacco smoke [3]. Branched alkanes are important components of conventional diesel and jet fuels derived from petroleum [2,4]; synthetic Fischer-Tropsch diesel and jet fuels derived from coal, natural gas, and/or biomass [5,6]; and renewable diesel and jet fuels derived from thermochemical treatment of bio-derived fats and oils (e.g., hydrotreated renewable jet (HRJ) fuels) [7,8]. Detailed com...

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Section: Rapid Compression Machine Ignitionmentioning

confidence: 99%

A comprehensive combustion chemistry study of 2,5-dimethylhexane

Sarathy

Javed

Karsenty

et al. 2014

Combustion and Flame

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“…One example of a modeling approach to account for heat loss is the physics-based multi-zone model (MZM) proposed by Goldsborough et al [Goldsborough, Banyon, & Mittal, 2012]. With this approach, the pressure profile for an RCM experiment is calculated from the MZM.…”

Section: Original Multi-zone Modelmentioning

confidence: 99%

Application of a multi-zone model for the prediction of species concentrations in rapid compression machine experiments

Wilson

Allen

2016

Combustion and Flame

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Accurate chemical kinetic models, which predict species evolution and heat release rates in chemically reactive systems, are essential for further advancements in fuel and combustion technology. An experimental facility that is widely used for evaluating the accuracy of kinetic models is a rapid compression machine (RCM), which creates a well-defined reaction environment by compressing a reactive mixture inside a chamber. Generally, RCM experiments are conducted in order to obtain ignition delay data. However, chemical speciation data provides greater insight into reaction pathways, and is therefore a more rigorous benchmark for validating kinetic models.In order for a chemical kinetic model to be evaluated using RCM data, the kinetic model must be coupled with a thermodynamic model that can predict the temporally varying conditions that evolve during an RCM experiment. The most common approach is to utilize a thermally and compositionally homogeneous 0-dimensional reactor model (HRM), which predicts conditions inside the hot core region of the main combustion chamber of an RCM, where a significant portion of the chemical reaction in an RCM takes place. This approach requires an effective volume profile, which is derived from the pressure profile of either a non-reactive experiment with similar transport properties as the condition of interest, or a separate multi-zone model (MZM), via the relationship between pressure and volume for an isentropic process. While HRMs have been shown to yield adequate ignition delay predictions, they cannot be used to predict average speciation data, since the conditions in the core region vary considerably from the average conditions of the total reaction chamber.This work introduces a modified MZM, which simulates chemical reaction throughout the entire temperature-varying main combustion chamber of an RCM, in addition to boundary work, conduction, and crevice flows as the traditional MZM approach. Simulating chemistry in the MZM allows for average speciation predictions, and eliminates the need for an HRM. The new approach is shown to yield similar average speciation data as CFD simulations (within 15% difference) for the combustion of primary reference fuels at various conditions. iii ACKNOWLEDGEMENTS

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“…Zone interactions are handled by specifying energy-and mass-transfer boundary conditions. For example, recent work by Goldsborough et al [61] divided the reaction chamber and piston into four zones, including the reaction chamber, the piston gap, the crevice volume, and the ringpack used to seal the piston in the reaction chamber. Using these zones, it was found [61] [61].…”

Section: Adequacy Of Zero-dimensional Approach In Rcm Modelingmentioning

confidence: 99%

“…For example, recent work by Goldsborough et al [61] divided the reaction chamber and piston into four zones, including the reaction chamber, the piston gap, the crevice volume, and the ringpack used to seal the piston in the reaction chamber. Using these zones, it was found [61] [61]. Two MZM-based methodologies to account for multi-stage ignition effects were recently proposed by Goldsborough et al [62] in an attempt to improve the robustness of homogeneous reactor modeling of RCM experiments.…”

Section: Adequacy Of Zero-dimensional Approach In Rcm Modelingmentioning

confidence: 99%

“…[60] and references therein. Several researchers have applied MZM to RCMs in order to improve model fidelity while retaining the simplicity and computational effort required for zero-D models [e.g., 29,61,62]. MZM typically divides the reaction chamber and piston assembly of the RCM into several zones, each of which are simulated separately.…”

Section: Adequacy Of Zero-dimensional Approach In Rcm Modelingmentioning

confidence: 99%

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Using rapid compression machines for chemical kinetics studies

Sung¹,

Curran²

2014

Progress in Energy and Combustion Science

260

127

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Rapid compression machines (RCMs) are used to simulate a single compression stroke of an internal combustion engine without some of the complicated swirl bowl geometry, cycle-to-cycle variation, residual gas, and other complications associated with engine operating conditions. RCMs are primarily used to measure ignition delay times as a function of temperature, pressure, and fuel/oxygen/diluent ratio; further they can be equipped with diagnostics to determine the temperature and flow fields inside the reaction chamber and to measure the concentrations of reactant, intermediate, and product species produced during combustion. This paper first discusses the operational principles and design features of RCMs, including the use of creviced pistons, which is an important feature in order to suppress the boundary layer, preventing it from becoming entrained into the reaction chamber via a roll-up vortex. The paper then discusses methods by which experiments performed in RCMs are interpreted and simulated. Furthermore, differences in measured ignition delays from RCMs and shock tube facilities are discussed, with the apparent initial gross disagreement being explained by facility effects in both types of experiments. Finally, future directions for using RCMs in chemical kinetics studies are also discussed.

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A computationally efficient, physics-based model for simulating heat loss during compression and the delay period in RCM experiments

Cited by 38 publications

References 58 publications

A comprehensive combustion chemistry study of 2,5-dimethylhexane

A comprehensive combustion chemistry study of 2,5-dimethylhexane

Application of a multi-zone model for the prediction of species concentrations in rapid compression machine experiments

Using rapid compression machines for chemical kinetics studies

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