Impact of nitric oxide on n-heptane and n-dodecane autoignition in a new high-pressure and high-temperature chamber

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Spray and Combustion Characterizations of Acetone-Butanol-Ethanol (ABE) blend at High-Pressure and High-Temperature Conditions

ÈN] Abstract The intermediate fermentation mixture of butanol production, Acetone, Butanol and Ethanol (ABE), is increasingly considered as a new alternative fuel in CI engines due to its physical and chemical properties, which are similar to those of butanol, and its advantages of no additional cost or energy consumption due to butanol separation. In a previous study, the High-Pressure and High-Temperature (HPHT) chamber, called ‘New One Shot Engine” (NOSE), was used to investigate macroscopic spray-combustion parameters by validating Spray-A conditions of the Engine Combustion Network. The present study concerns the spray-combustion characteristics of the ABE mixture (volume ratio 3:6:1), blended with n-dodecane at a volumetric ratio of 20% (ABE20), compared to n-dodecane as reference fuel. The macroscopic spray and combustion parameters were investigated, for non-reactive conditions, in pure Nitrogen and for reactive conditions, in 15% oxygen, at ambient pressure (60 bar), ambient density (22.8 kg/m3 ) and different ambient temperatures (800 K, 850 K and 900 K). The liquid and vapor spray penetrations were investigated by the Diffused Back Illumination (DBI) and Schlieren techniques in non-reactive conditions. In reactive conditions, the lift-off length was measured by OH* chemiluminescence images at 310 nm. The Schlieren technique was also used to verify the choice of detection criterion. The ignition delay results of the two fuels were compared. It was found that the behavior of the two fuels as a function of temperature was similar even if the liquid length of ABE20 was shorter than that of n-dodecane at all ambient temperatures. On the other hand, no real difference in vapor spray penetration between the two fuels was observed. The vaporization properties and the lower autoignition ability of ABE20 led to longer ignition delays and lift-off length.The authors acknowledge the National Research Agency (contract ANR-14-CE22-0015-01) for financial support to the ECN-France project and Region Centre Val de Loire (CPER 2007-2013 Energies du Futur) and FEDER for financial support to build the experimental set-up. We also thank G.Bruneaux and M.Bardi from IFPen for interesting discussions that helped us to refine the analysis.Nilaphai, O.; Ajrouche, H.; Hespel, C.; Moreau, B.; Chanchaona, S.; Foucher, F.; Mounaïm-Rousselle, C. (2017). Spray and Combustion Characterizations of Acetone-Butanol-Ethanol (ABE) blend at High-Pressure and High-Temperature Conditions. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 798-805. https://doi.org/10.4995/ILASS2017.2017.4852OCS79880

Characterization of the ECN spray A in different facilities. Part 1: boundary conditions characterization

The Engine Combustion Network (ECN) community has greatly contributed to improve the fundamental understanding of spray atomization and combustion at conditions relevant to internal combustion engines. In this context, standardized spray experiments have been defined to facilitate the comparison of experimental and simulation studies performed in different facilities and with different models. This operating mode promotes collaborations among research groups and accelerates the advancement of research on spray. In efforts to improve the comparability of the ECN spray A experiments, it is of high importance to review the boundary conditions of different devices used in the community. This work is issued from the collaboration in the ECN France project, where two new experimental facilities from PPRIME (Poitiers) and PRISME (Orleans) institutes are validated to perform spray A experiments. The two facilities, based on Rapid Compression Machine (RCM) design, have been investigated to characterize their boundary conditions (e.g., flow velocity as well as fuel and gas temperatures). A set of standardized spray experiments were performed to compare their results with those obtained in other facilities, in particular the Constant Volume Pre-burn (CVP) vessel at IFPEN. It is noteworthy that it is the first time that RCM type facilities are used in such a way within the ECN. This paper (part 1) focuses on the facilities description and the fine characterization of their boundary conditions. A further paper (part 2) will present the results obtained with the same facilities performing ECN standard spray A characterizations. The reported review of thermocouple thermometry highlights that it is necessary to use thin-wires and bare-bead junction as small as possible. This would help to measure the temperature fluctuations with a minimal need for error corrections, which are highly dependent on the proper estimation of the velocity through the junction, and therefore it may introduce important uncertainties. Temperature heterogeneities are observed in all spray A devices. The standard deviation of the temperature distribution at the time of injection is approximately 5%. We report time-resolved temperature measurement from PPRIME RCM, performed in the near nozzle area during the injection. In inert condition, colder gases from the boundary layer are entrained toward the mixing area of the spray causing a further deviation from the target temperature. This emphasizes the importance of the temperature in the boundary (wall) layer. In reacting condition, the temperature of these entrained gases increases by the effect of the increased pressure, as the RCM has a relatively small volume. Generally, the velocity and turbulence levels are an order of magnitude higher in RCM and constant pressure flow compared to CVP vessels. The boundary characterization presented here will be the base for discussing spray behavior in the part 2 of this paper

Characterization of the ECN spray A in different facilities. Part 2: spray vaporization and combustion

One of the objective of Engine Combustion Network (ECN), (https://ecn.sandia.gov