scholarly journals Numerical Investigation of the Chemical Effect and Inhibition Effect Improvement of C3H2F3Br (2-BTP) Using the Perfectly Stirred Reactor Model

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2670
Author(s):  
Ping Li ◽  
Bo Ke ◽  
Jian Zhang ◽  
Xianfeng Chen
Keyword(s):  
Numerical Investigation ◽  
Chemical Effect ◽  
Reactor Model ◽  
Hydrocarbon Flames ◽  
Inhibition Effect ◽  
Chemical Effects ◽  
Stirred Reactor ◽  
Combustion Enhancement ◽  
Co2 Addition ◽  
Chemical Rate

The overall chemical rate and chemical effect of CF3Br, 2-BTP and 2-BTP/CO2 with hydrocarbon flames are calculated using the perfectly stirred reactor (PSR) model. The chemical effects of CF3Br with CH4/air flames always inhibit combustion. The chemical saturation concentration of CF3Br in stoichiometric and lean (Φ = 0.6) CH4/air flames at 298 K and 1 bar is roughly 2.5% and 0.8%, respectively. The overall chemical rate of 2-BTP with moist C3H8/air flames is always less than the uninhibited condition and fluctuates with sub-inerting agent additions. The net chemical effect variation of 2-BTP is more complicated than experimented and calculated flame speeds with 2-BTP added to lean hydrocarbon flames. There are negative chemical effects (chemical combustion effects) with certain sub-inerting 2-BTP concentrations (0.015 ≤ Xa ≤ 0.034), which result in the experimented unwanted combustion enhancement in lean moist C3H8/air flames. CO2 can obviously improve the inhibition effect of 2-BTP in lean moist C3H8/air flames, driving negative chemical effects (enhance combustion) into positive chemical effects (inhibit combustion) with lean moist C3H8/air flames. No enhanced combustion would occur with the blends (2-BTP/CO2) when CO2 addition is larger than 4% in Φ = 0.6 moist C3H8/air flames at 298 K and 1 bar.

Investigation of nitrite pathways in sugar beet extraction

2014 ◽  
pp. 626-635 ◽  
Author(s):  
Florian Emerstorfer ◽  
Christer Bergwall ◽  
Walter Hein ◽  
Mats Bengtsson ◽  
John P. Jensen
Keyword(s):  
Sugar Beet ◽  
Laboratory Experiments ◽  
Ph Value ◽  
Full Scale ◽  
Chemical Effect ◽  
Spectrophotometric Detection ◽  
Sugar Factory ◽  
Chemical Effects ◽  
Set Up ◽  
Nitrate And Nitrite

The investigations presented in this work were carried out in order to further deepen the knowledge about nitrite pathways in the area of sugar beet extraction. The article consists of two parts with different experimental set-up: the first part focuses on laboratory trials in which the fate of nitrate and nitrite was studied in a so-called mini-fermenter. These trials were carried out using juice from the hot part of the cossette mixer of an Agrana sugar factory in Austria. In the experiments, two common sugar factory disinfectants were used in order to study microbial as well as microbial-chemical effects on nitrite formation and degradation caused by bacteria present in the juice. The trials demonstrated that the direct microbial effect (denitrification) on nitrite degradation is more pronounced than the indirect microbial-chemical effect coming from pH value decrease by these bacteria and subsequent nitrite loss. The second part describes the findings from laboratory experiments and full scale factory trials using a mobile laboratory set-up based on insulated stainless steel containers and spectrophotometric detection of nitrite in various factory juices. The trials were made at two Nordzucker factories located in Finland (factory A) and Sweden (factory B). The inhibiting effect of the two common sugar factory disinfectants on nitrite formation was evaluated in laboratory trials, whereas the full scale trials focused on one disinfectant. Other trials to evaluate potential contamination sources of thermophilic nitrite producing bacteria to the extraction system, reactivation of nitrite producing bacteria in raw juice and the effect of a pH gradient on bacterial nitrite activity in cossette mixer juice are also reported.

A Multidisciplinary Approach for the Comprehensive Assessment of Integrated Rotorcraft–Powerplant Systems at Mission Level

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Ioannis Goulos ◽  
Fakhre Ali ◽  
Konstantinos Tzanidakis ◽  
Vassilios Pachidis ◽  
Roberto d'Ippolito
Keyword(s):  
Environmental Impact ◽  
Fuel Consumption ◽  
Comprehensive Assessment ◽  
Pollutant Emissions ◽  
Operational Performance ◽  
Civil Aviation ◽  
Accurate Estimation ◽  
Nox Emissions ◽  
Reactor Model ◽  
Stirred Reactor

This paper presents an integrated methodology for the comprehensive assessment of combined rotorcraft–powerplant systems at mission level. Analytical evaluation of existing and conceptual designs is carried out in terms of operational performance and environmental impact. The proposed approach comprises a wide-range of individual modeling theories applicable to rotorcraft flight dynamics and gas turbine engine performance. A novel, physics-based, stirred reactor model is employed for the rapid estimation of nitrogen oxides (NOx) emissions. The individual mathematical models are implemented within an elaborate numerical procedure, solving for total mission fuel consumption and associated pollutant emissions. The combined approach is applied to the comprehensive analysis of a reference twin-engine light (TEL) aircraft modeled after the Eurocopter Bo 105 helicopter, operating on representative mission scenarios. Extensive comparisons with flight test data are carried out and presented in terms of main rotor trim control angles and power requirements, along with general flight performance charts including payload-range diagrams. Predictions of total mission fuel consumption and NOx emissions are compared with estimated values provided by the Swiss Federal Office of Civil Aviation (FOCA). Good agreement is exhibited between predictions made with the physics-based stirred reactor model and experimentally measured values of NOx emission indices. The obtained results suggest that the production rates of NOx pollutant emissions are predominantly influenced by the behavior of total air inlet pressure upstream of the combustion chamber, which is affected by the employed operational procedures and the time-dependent all-up mass (AUM) of the aircraft. It is demonstrated that accurate estimation of on-board fuel supplies ahead of flight is key to improving fuel economy as well as reducing environmental impact. The proposed methodology essentially constitutes an enabling technology for the comprehensive assessment of existing and conceptual rotorcraft–powerplant systems, in terms of operational performance and environmental impact.

Coherent Flame Model to Predict Formation Pollutants in Turbulent Premixed Flame

2010 ◽  
Author(s):  
Abdelhalim Bentebbiche ◽  
Denis Veynante
Keyword(s):  
Kinetic Scheme ◽  
Turbulent Flames ◽  
Premixed Flame ◽  
Reactive Flow ◽  
Reactor Model ◽  
Turbulent Premixed Flame ◽  
No Formation ◽  
Stirred Reactor ◽  
Good Issue ◽  
Turbulent Premixed

The objective of this work is to analyze and to model the turbulent flames in the context of coherent flame model. We present a detailed description of equations and the flamelet regimes in turbulent premixed flame. A surface density models proposed here represents a good issue for numerical simulation. Extension of coherent flame model and homogenous stilled reactor model is proposed to consider the dynamics behavior of flame and pollutants formation. From the results of this work it is concluded that the coherent flame model allows surpassing difficulties of the turbulent reactive flow modeling. Calculations based on a semi-global kinetic scheme and flamelet formulation combined with a well stirred reactor analysis of the burnt gases are used and provided reasonably accurate values of CO and NO formation. Also, we have observed that CO is formed near the reaction zone (front flame) but emission of CO2, H2O and NO are formed in the hot gases.

scholarly journals Thermo diffusion and chemical effects with simultaneous thermal and mass diffusion in MHD mixed convection flow with ohmic heating

2010 ◽  
Vol 6 (2) ◽  
pp. 84-93 ◽  
Author(s):  
N Ananda Reddy ◽  
SVK Varma ◽  
MC Raju
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Ohmic Heating ◽  
Soret Effect ◽  
Fluid Velocity ◽  
Chemical Effect ◽  
Convection Flow ◽  
Heated Plate ◽  
Mixed Convection Flow ◽  
Chemical Effects

Thermo diffusion and chemical effects on heat transfer in MHD mixed convection flow and masstransfer past an infinite vertical plate with Ohmic heating and viscous dissipation have beenstudied. Approximate solutions have been derived for velocity, temperature, concentration profiles,skin friction, rate of heat transfer and rate of mass transfer using perturbation technique. Theobtained results are discussed with the help of graphs to observe the effect of various parameterslike Schmidt number (Sc), Prandtl number (Pr), Magnetic parameter (M),Soret number (So) andchemical parameter (K), taking two cases viz. Case I: when Gr > 0 (flow on cooled plate) and CaseII: Gr < 0 (flow on heated plate). Thermal diffusion causes both the fluid velocity and temperature tofall due to the presence of the chemical effect. Velocity and temperature profiles are higher formercury than electrolytic solution. Soret effect increased the concentration of the fluid while chemicaleffect decreased.Keywords: Chemical effect; thermo diffusion; magnetic field; heat-mass transfer.DOI: 10.3329/jname.v6i2.3761

Numerical Investigation of the Effect of Impeller Design Parameters on the Performance of a Multiphase Baffle-Stirred Reactor

2011 ◽  
Vol 34 (8) ◽  
pp. 1271-1280 ◽  
Author(s):  
A. Iranzo ◽  
R. Barbero ◽  
J. Domingo ◽  
D. Cuadra ◽  
J. Costa ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Design Parameters ◽  
Stirred Reactor

scholarly journals A Model for Bluff Body Flame Stabilization

1986 ◽  
Author(s):  
J. A. De Champlain ◽  
M. F. Bardon
Keyword(s):  
Experimental Data ◽  
Equivalence Ratio ◽  
Bluff Body ◽  
Laminar Flame ◽  
Flame Stabilization ◽  
Effect Of Temperature ◽  
Laminar Flame Speed ◽  
Tabular Form ◽  
Chemical Effects ◽  
Stirred Reactor

Previous work on bluff body stabilization mechanisms is reviewed, and existing models are categorized in tabular form, showing the underlying assumptions and resulting equations. Lacunae in existing models are discussed, particularly their reliance on characteristics such as laminar flame speed which is difficult to predict for the conditions encountered in turbojet afterburners. A model for bluff body flame stabilization is proposed based on the stirred reactor approach. In addition to the effect of temperature, pressure and geometry, it includes chemical effects such as vitiation and fuel-air equivalence ratio. Blow off velocities predicted by the model are compared to experimental data for various conditions.

Micro-Kinetic Study of Reduction of NO on Pt Group Catalysts

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Dinesh B Mantri ◽  
Preeti Aghalayam
Keyword(s):  
Reaction Mechanism ◽  
Surface Coverage ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Effect Of Temperature ◽  
Exponential Potential ◽  
Reactor Model ◽  
Reduction Activity ◽  
Stirred Reactor ◽  
High Durability

Catalytic reduction using CO has significant potential for the control of NOx using Pt group catalysts as CO is already present in the exhausts and Pt group catalysts have high durability in the presence of SO2 and H2O. Different reaction mechanisms are given in the literature for this reaction based on NO dissociation, -NCO formation and so on, but the exact reaction mechanism capable of capturing experimentally observed features is as yet unavailable. To determine the kinetics and reaction mechanism, we propose here an elementary reaction mechanism based on NO dissociation applicable to Pt group catalysts and simulated with CHEMKIN 4.0.2 using single and multiple PSR (Perfectly Stirred Reactor) model. The activation energies of the elementary steps are found from the Unity Bond Index-Quadratic Exponential Potential (UBI-QEP) method. Excellent agreement between literature experiments and our simulation results are observed for the NO-CO reaction on Pt and Rh catalysts and for the NO-CO-O2 reaction on Ir catalyst. The effect of temperature on the NO reduction activity is captured well by the model. Additionally the simulations can also point towards importance of particular reactions, selectivity to N2, effects of surface coverage, effects of residence time and catalytic surface area on NO reduction.

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