scholarly journals The Influence of the Distributed Reaction Regime on Fuel Reforming Conditions

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Richard Scenna ◽  
Ashwani K. Gupta
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Soot Formation ◽  
Product Distribution ◽  
Fuel Reforming ◽  
Length Scales ◽  
Reaction Regime ◽  
Available Information ◽  
Kinetics Of ◽  
Reforming Reactions

Previous works have demonstrated that the distributed reaction regime improved the reformate product distribution, prevented soot formation, and favored higher hydrogen yields. The experimental data from these works and additional literature focusing on individual reactions provided an insight into how the distributed reaction regime influenced the reformate product composition. The distributed reaction regime was achieved through the controlled entrainment of hot reactive products (containing heat, carbon dioxide, steam and reactive radicals and species) into the premixed fuel air mixture, elongating the chemical time and length scales. High velocity jets enhanced mixing, while shortening the time and length scales associated with transport. As some steam and carbon dioxide will form in the reforming process, it was theorized that the mixing of the entrained flow (containing heat, carbon dioxide, and steam) into the premixed fuel air mixture promoted dry and steam reforming reactions, improving conversion. The available information on chemical kinetics of reformation is rather limited. In this work, the activity and timescales of these reactions were determined from the available experimental data. This was then used to assess which reactions were active under Distributed Reforming conditions. These data help in the design and development of advanced reformers using distributed reforming conditions.

Influence of Distributed Reaction Regime on Fuel Reforming

2017 ◽  
Author(s):  
Richard Scenna ◽  
Ashwani K. Gupta
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Time Scales ◽  
Steam Reforming ◽  
Product Distribution ◽  
Fuel Reforming ◽  
Entrained Flow ◽  
Kinetic Information ◽  
Reaction Regime ◽  
Reforming Reactions

Previous works have demonstrated that the Distributed Reaction regime impact on the reformate product distribution. Using previous works, a theory of how the Distributed Reaction regime influences the reformate product composition is provided. Distributed Reaction regime is achieved by entraining exhaust products into the premixed fuel air mixture. As some steam and carbon dioxide will form in the exhaust, it is theorized that the mixing of the entrained flow (containing heat, carbon dioxide, and steam) into the premixed fuel air mixture will promote dry and steam reforming reactions, improving conversion. As kinetic information on reforming literature is limited, the activity and time scales of these reactions were determined from existing experimental data. This was then used to determine which reactions were active under Distributed Reforming conditions.

Wet Partial Oxidation of JP8 in a Well-Insulated Reactor

2016 ◽  
Author(s):  
Richard Scenna ◽  
Ashwani K. Gupta
Keyword(s):  
Carbon Monoxide ◽  
Power Systems ◽  
Partial Oxidation ◽  
Soot Formation ◽  
Catalytic Reforming ◽  
High Sulfur Content ◽  
Reaction Regime ◽  
Reduced Costs ◽  
Direct Use ◽  
Reforming Reactions

This work investigates wet and dry non-catalytic partial oxidation of JP8 under distributed reaction regime condition. Previous works have demonstrated the potential of the distributed reaction regime to increase hydrogen and carbon monoxide production over conventional non-catalytic reforming and suppress soot formation inside the reactor. Jet propellant 8 (JP8) has a high sulfur content (up to 3000ppm) and a tendency to form coke, making it an ideal candidate for this non-catalytic approach. Experimental results are reported with the reactor operated at fixed oxygen to carbon ratio of 1.08 and steam to carbon ratios varied from 0.0 to 0.23. Numerical simulations were used to determine flame regime and extent of distribution. Steam provided favorable effects even with trace amounts (S/C=0.01), but more pronounced effects were observed at steam to carbon ratio of 0.17. Syngas composed of 22.5–24.6% hydrogen and 20.1–23.3% carbon monoxide was evolved. Of the hydrocarbons detected, only methane was seen in finite amounts (0.17–0.29%). The increase in performance in terms of reforming efficiency and conversion exceeded what can be ascribed to steam reforming reactions alone. Additional enhancement is attributed to distributed reaction in the reactor. Reforming efficiency of approximately 68–80% is comparable to that from catalytic reforming. Low steam to carbon ratio offers higher sustainability in mobile power systems at reduced costs from direct use of water recovered from fuel cells.

Soot Formation Reaction Effect in Modeling Thermal Partial Oxidation of Jet-A

2014 ◽  
Author(s):  
Richard Scenna ◽  
Ashwani K. Gupta
Keyword(s):  
Experimental Data ◽  
Carbon Monoxide ◽  
Partial Oxidation ◽  
Kinetic Models ◽  
Soot Formation ◽  
Radical Formation ◽  
Fuel Reforming ◽  
Chemical Modeling ◽  
Formation Reaction ◽  
One Dimensional

The results obtained from the modeling of thermal partial oxidation of kerosene based Jet-A fuel are presented using one dimensional chemical modeling. Two detailed kinetic models for alkenes chemistry ranging between C8 to C16 were evaluated and compared against experimental data of thermal partial oxidation of Jet-A fuel. The key difference between these two kinetic models was the inclusion of model for soot formation reactions. Chemical modeling was performed using dodecane to represent Jet-A fuel. The results showed that the model with soot reactions was significantly more accurate in predicting reformate products from Jet-A. In particular, the formation of carbon monoxide, methane and acetylene closely followed the experimental data with the model that included soot formation reactions. The results revealed that the soot formation reactions promoted the smaller hydrocarbons to decompose via the alternate kinetic pathways and from additional radical formation. The results also reveal that the inclusions of soot formation reactions are critical in the modeling of thermal partial oxidation of fuels for fuel reforming.

Effect of Oxygen Concentration on Distributed Flame Regime

2017 ◽  
Author(s):  
Richard Scenna ◽  
Ashwani K. Gupta
Keyword(s):  
Carbon Monoxide ◽  
Oxygen Concentration ◽  
Chemical Reaction ◽  
Partial Oxidation ◽  
Product Distribution ◽  
Length Scales ◽  
Reaction Condition ◽  
Effect Of Oxygen ◽  
Reforming Reactions ◽  
Oxygen Concentrations

This work investigated the effect of oxygen concentrations in the reactor on the partial oxidation of JP8 under the distributed reaction condition. Reforming efficiency as high as 74% was achieved; syngas composition consisted of 20.7 to 22.3% hydrogen and 20.2 to 21.5% carbon monoxide. Reformate product distribution and quality was found to depend on the reactor oxygen concentrations and, to a lesser extent on flame regime. Previous works operating at similar conditions found that higher reformate quality was associated with the more distributed reactor conditions. An increase in reactor oxygen concentrations fostered a more rapid chemical reaction, which shortened chemical time and length scales. While this resulted in a less distributed reactor, the potential decrease in reformate quality was offset by the increased availability of oxygen. As the reactions were limited by the availability of oxygen, the addition of oxygen enhanced the extent of reforming reactions, to promote increased conversion and reforming efficiency.

Kinetics of pH equilibration in solutions of hydrogen carbonate during bubbling with a gas containing carbon dioxide

1985 ◽  
Vol 50 (3) ◽  
pp. 553-558
Author(s):  
Karel Lívanský
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Chemical Equilibrium ◽  
Reaction Rate ◽  
Sudden Change ◽  
Hydrogen Carbonate ◽  
Equilibrium Data ◽  
Chemical Reaction Rate ◽  
Kinetics Of ◽  
Good Agreement

The kinetics of the title process is approximated by differential equations based on kinetic and equilibrium data for carbon dioxide. The course of pH after a sudden change of the concentration of CO2 in the gas is calculated by numerical integration. The course of pH during absorption of CO2 is different from that during desorption. The course of pH during desorption calculated on the assumption that the rate of the noncatalysed hydration of CO2 is sufficient to ensure chemical equilibrium is in good agreement with experimental data from the literature. During absorption of CO2 in a solution of hydrogen carbonate, the chemical reaction rate is sometimes insufficient to ensure chemical equilibrium prior to pH measurement.

Kinetics of the carbon monoxide conversion with steam at elevated pressures

1979 ◽  
Vol 44 (3) ◽  
pp. 652-659 ◽  
Author(s):  
Pavel Fott ◽  
Jan Vosolsobě ◽  
Vladimír Glaser
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Reaction Kinetics ◽  
Gaseous Phase ◽  
Reaction Rate ◽  
Surface Reaction ◽  
Elevated Pressures ◽  
Limiting Step ◽  
Kinetics Of

The kinetics of the carbon monoxide conversion with steam on a Czechoslovak FeCr catalyst was investigated. The experimental data were obtained on a gradient-free differential reactor with recirculating gaseous phase at temperatures of 633 and 693 K and pressures from the range 0.1-0.9 MPa. The evaluation of experimental data showed that the reaction rate increases with increasing pressure according to a downward convex and that it also increases with increasing content of carbon monoxide in the gas and with decreasing content of carbon dioxide. The reaction kinetics was described by an equation derived from the Langmuir-Hinshelwood concept for the case when the limiting step of the reaction is a surface reaction.

A fuzzy neural network approach for modeling the growth kinetics of FeB and Fe2B layers during the boronizing process

2018 ◽  
Vol 106 (6) ◽  
pp. 603 ◽  
Author(s):  
Bendaoud Mebarek ◽  
Mourad Keddam
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Fuzzy Neural Network ◽  
Treatment Time ◽  
Calculation Model ◽  
Average Error ◽  
Network Approach ◽  
Neural Network Approach ◽  
Fuzzy Neural ◽  
Kinetics Of

In this paper, we develop a boronizing process simulation model based on fuzzy neural network (FNN) approach for estimating the thickness of the FeB and Fe2B layers. The model represents a synthesis of two artificial intelligence techniques; the fuzzy logic and the neural network. Characteristics of the fuzzy neural network approach for the modelling of boronizing process are presented in this study. In order to validate the results of our calculation model, we have used the learning base of experimental data of the powder-pack boronizing of Fe-15Cr alloy in the temperature range from 800 to 1050 °C and for a treatment time ranging from 0.5 to 12 h. The obtained results show that it is possible to estimate the influence of different process parameters. Comparing the results obtained by the artificial neural network to experimental data, the average error generated from the fuzzy neural network was 3% for the FeB layer and 3.5% for the Fe2B layer. The results obtained from the fuzzy neural network approach are in agreement with the experimental data. Finally, the utilization of fuzzy neural network approach is well adapted for the boronizing kinetics of Fe-15Cr alloy.

Features of the kinetics of cyclic elastoplastic deformation diagrams at dwells in cycles and superimposition of variable stresses on them

2020 ◽  
Vol 86 (12) ◽  
pp. 46-53
Author(s):  
M. M. Gadenin
Keyword(s):  
Experimental Data ◽  
Elastoplastic Deformation ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Loading Cycle ◽  
Additional Variable ◽  
Dynamic Creep ◽  
Variable Stresses ◽  
Kinetics Of ◽  
Deformation Diagrams

The goal of the study is determination of the regularities of changes in cyclic strains and related deformation diagrams attributed to the existence of time dwells in the loading modes and imposition of additional variable stresses on them. Analysis of the obtained experimental data on the kinetics of cyclic elastoplastic deformation diagrams and their parameters revealed that in contrast to regular cyclic loading (equal in stresses), additional deformations of static and dynamic creep are developed. The results of the studys are especially relevant for assessing the cyclic strength of unique extremely loaded objects of technology, including nuclear power equipment, units of aviation and space systems, etc. The experiments were carried out on the samples of austenitic stainless steel under low-cycle loading and high temperatures of testing. Static and dynamic creep deformations arising under those loading conditions promote an increase in the range of cyclic plastic strain in each loading cycle and also stimulate an increase in the range of elastoplastic strain due to active cyclic deformation. At the same time the existence of dwells on extrema of stresses in cycles without imposition of additional variable stresses on them most strongly affects the growth of plastic strain ranges in cycles. Imposition of additional variable stresses on dwells also results in the development of creep strains, but their growth turns out to be somewhat less than in the presence of dwells without stresses imposed. The diagrams of cyclic deformation obtained in the experiments are approximated by power dependences, their kinetics being described in terms of the number of loading cycles using corresponding temperature-time functions. At the same time, it is shown that increase in the cyclic plastic deformation for cycles with dwells and imposition of additional variable stresses on them decreases low cycle fatigue life compared to regular loading without dwells at the same stress amplitudes, moreover, the higher the values of static and dynamic creep, the greater decrease in low-cycle fatigue life. This conclusion results from experimental data and analysis of conditions of damage accumulation for the considered forms of the loading cycle using the deformation criterion of reaching the limit state leading to fracture.

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