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Статті в журналах з теми "Endothermic reaction"

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Автор: Grafiati

Опубліковано: 14 березня 2023

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1

CONROY, DEVIN T., and STEFAN G. LLEWELLYN SMITH. "Endothermic and exothermic chemically reacting plumes." Journal of Fluid Mechanics 612 (October 10, 2008): 291–310. http://dx.doi.org/10.1017/s0022112008002917.

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Анотація:

We develop a model for a turbulent plume in an unbounded ambient that takes into account a general exothermic or endothermic chemical reaction. These reactions can have an important effect on the plume dynamics since the entrainment rate, which scales with the vertical velocity, will be a function of the heat release or absorption. Specifically, we examine a second-order non-reversible reaction, where one species is present in the plume from a pure source and the other is in the environment. For uniform ambient density and species fields the reaction has an important effect on the deviation from pure plume behaviour as defined by the source parameter Γ. In the case of an exothermic reaction the density difference between the plume and the reference density increases and the plume is ‘lazy’, whereas for an endothermic reaction this difference decreases and the plume is more jet-like. Furthermore, for chemical and density-stratified environments, the reaction will have an important effect on the buoyancy flux because the entrainment rate will not necessarily decrease with distance from the source, as in traditional models. As a result, the maximum rise height of the plume for exothermic reactions may actually decrease with reaction rate if this occurs in a region of high ambient density. In addition, we investigate non-Boussinesq effects, which are important when the heat of reaction is large enough.

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2

Zhou, Guang Fen, Jie Ren, and Shao Wen Zhang. "Initial Surface Reactions Mechanisms of Atomic Layer Deposition TiO₂Using Ti(OCH₃)₄ and H₂O as Precursors." Advanced Materials Research 785-786 (September 2013): 832–36. http://dx.doi.org/10.4028/www.scientific.net/amr.785-786.832.

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The initial surface reaction mechanisms of atomic layer depositionTiO2using Ti (OCH3)4and H2O as the precursors are investigated by density functional theory. The ALD process is divided into two half-reactions, i.e., Ti (OCH3)4and H2O half-reactions. The adsorption of Ti (OCH3)4on OH/Si (100)2×1 surface is exothermic. However, the overall reaction of Ti (OCH3)4is endothermic. In addition, H2O half-reactions are endothermic and thermodynamically unfavorable.

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3

Wu, Jun-Lin, Zhi-Hui Li, Ao-Ping Peng, Xing-Cai Pi, and Xin-Yu Jiang. "Utility computable modeling of a Boltzmann model equation for bimolecular chemical reactions and numerical application." Physics of Fluids 34, no. 4 (April 2022): 046111. http://dx.doi.org/10.1063/5.0088440.

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A Boltzmann model equation (kinetic model) involving the chemical reaction of a multicomponent gaseous mixture is derived based on Groppi's work [“A Bhatnagar–Gross–Krook-type approach for chemically reacting gas mixtures,” Phys. Fluids 16, 4273 (2004)], in which the relaxation parameters of elastic collision frequency for rigid elastic spheres are obtained based on the collision term, and the pivotal collision frequency of the chemical reaction is deduced from the chemical reaction rate that is determined by the direct simulation Monte Carlo (DSMC) method. This kinetic model is shown to be conservative, and the H theorem for an endothermic reaction is proven. In the framework of the gas-kinetic unified algorithm, the discrete velocity method, finite volume method, and implicit scheme are applied to solve the proposed kinetic model by introducing a suitable boundary condition at the wall surface. For hypersonic flows around a cylinder, the proposed kinetic model and the corresponding numerical methods are verified for both endothermic and exothermic reactions by comparison of the model's results with results from the DSMC method. The different influences of endothermic and exothermic reactions are also given. Finally, the proposed kinetic model is also used to simulate an exothermic reaction-driven flow in a square cavity.

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4

Subbarao, Duvvuri, Reem Hassan Abd Elghafoor Hassan, and Marappagounder Ramasamy. "Heat Transfer with Chemical Reaction in Wall Heated Packed Bed Reactor." Applied Mechanics and Materials 625 (September 2014): 722–25. http://dx.doi.org/10.4028/www.scientific.net/amm.625.722.

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Анотація:

Information on wall heat transfer to packed bed reactors operating with exothermic or endothermic reactions is scarce. Overall wall heat transfer coefficients in a packed bed reactor in presence of an endothermic reaction are measured and observed to be smaller than the expected in the absence of reaction. This observation is in contrast with the reported observations with exothermic reactions in packed beds. A model equation based on energy balance is presented to explain the observations.

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5

Sobel, D. R., and L. J. Spadaccini. "Hydrocarbon Fuel Cooling Technologies for Advanced Propulsion." Journal of Engineering for Gas Turbines and Power 119, no. 2 (April 1, 1997): 344–51. http://dx.doi.org/10.1115/1.2815581.

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Storable hydrocarbon fuels that undergo endothermic reaction provide an attractive heat sink for future high-speed aircraft. An investigation was conducted to explore the endothermic potential of practical fuels, with inexpensive and readily available catalysts, under operating conditions simulative of high-speed flight applications. High heat sink capacities and desirable reaction products have been demonstrated for n-heptane and Norpar 12 fuels using zeolite catalysts in coated-tube reactor configurations. The effects of fuel composition and operating condition on extent of fuel conversion, product composition, and the corresponding endotherm have been examined. The results obtained in this study provide a basis for catalytic-reactor/heat-exchanger design and analysis.

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6

Selim, Ezzat T. M., M. A. Rabbih та M. A. Fahmey. "Kinetic Energy Release and Position of the Transition State for С6Н7+ Ions Produced from Isomeric C7H8O Precursors". Zeitschrift für Naturforschung A 46, № 12 (1 грудня 1991): 1021–25. http://dx.doi.org/10.1515/zna-1991-1204.

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Abstract The energetic requirement and mechanisms for CHO' loss from the molecular ions of isomeric C7H8O precursors have been reported. The heat of formation of [C6H7]+ (protonated benzene) was determined and ε* evaluated. Measurement of the kinetic energy release TB gives the energy-partitioning quotients q= TB/εr* which range from 0.38 to 0.99. The energy available and TB are small for the strongly endothermic reaction of benzyl alcohol but increase sharply in the case of the weakly endothermic reaction of anisole. All reactions have "late" transition states, the position X0*of the transition state on the reaction coordinate varying from 0.64 to 0.93

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7

Stone, John Alfred, Xiaoping Li, and Patricia Anne Turner. "A high pressure mass spectrometric study of proton transfer between tri-, tetra-, penta-, and hexamethylbenzene." Canadian Journal of Chemistry 64, no. 10 (October 1, 1986): 2021–30. http://dx.doi.org/10.1139/v86-334.

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Анотація:

The proton affinities (PA) of some methylaromatic compounds and the rates of proton transfer reactions have been measured using high pressure mass spectrometry. The equilibria studied were of the form [Formula: see text]. Van't Hoff plots yielded the following PA values (kcal mol−1) relative to PA(ethylacetate) = 200.7 as standard: mesitylene 201.0, 1,2,3,5-tetramethylbenzene 203.2, pentamethylbenzene 204.4, hexamethylbenzene 206.6. ΔS0 values for the proton transfer equilibria are not fully determined by changes in rotational symmetry numbers and it is suggested that vibrational and torsional changes must be considered. Proton transfer is slow in both the forward (exothermic) and reverse (endothermic) directions and, in addition, for all except the most endothermic reaction studied (1,2,3,5-tetramethylbenzene + protonated hexamethylbenzene) the rate constants for proton transfer increase with decreasing temperature. Such behaviour can be associated with the potential energy profile along the reaction coordinate for the reaction. A limited number of charge transfer experiments involving molecular ions [Formula: see text] showed that reaction occurs at every collision in the forward (exothermic) direction and the reaction efficiency in the reverse (endothermic) direction is small but increases with increasing temperature.

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8

Watt, S. D., H. S. Sidhu, A. C. McIntosh, and J. Brindley. "Chaotic flow in competitive exothermic–endothermic reaction systems." Applied Mathematics Letters 115 (May 2021): 106960. http://dx.doi.org/10.1016/j.aml.2020.106960.

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9

Simon, P. L. "Inhibition of flame propagation by an endothermic reaction." IMA Journal of Applied Mathematics 68, no. 5 (October 1, 2003): 537–62. http://dx.doi.org/10.1093/imamat/68.5.537.

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10

Shen, Fan, Shao Long Huang, Zheng Sun, and Qing Jun Ding. "Research on Hardening Mechanism of Cement-Emulsified Asphalt-Epoxy Resin." Advanced Materials Research 430-432 (January 2012): 434–37. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.434.

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This article researched the cementation and hardening mechanisms of cement asphalt emulsion and waterborne epoxy mortar by using the XRD, and heat of hydration testing methods. The results of this study show that the mixture of cement with epoxy and cement- asphalt-epoxy are endothermic reaction. There are occurring endothermic reactions between cement with epoxy. The waterborne epoxy resin and basic structure unit of ettringite [Ca3Al(OH)6•12H2O] were reacted and formed Ca-complex at earlier period of hydration.

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11

Taskin, M. Ertan, Alexandre Troupel, Anthony G. Dixon, Michiel Nijemeisland, and E. Hugh Stitt. "Flow, Transport, and Reaction Interactions for Cylindrical Particles With Strongly Endothermic Reactions." Industrial & Engineering Chemistry Research 49, no. 19 (October 6, 2010): 9026–37. http://dx.doi.org/10.1021/ie1003619.

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12

Gubernov, V. V., A. V. Kolobov, A. A. Polezhaev, H. S. Sidhu, A. C. McIntosh, and J. Brindley. "Stabilization of combustion wave through the competitive endothermic reaction." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, no. 2180 (August 2015): 20150293. http://dx.doi.org/10.1098/rspa.2015.0293.

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Анотація:

In this paper, we numerically investigate the stability of propagating combustion waves in the competitive exothermic–endothermic reaction model. The analysis is based on the Evans function method and direct numerical integration of the governing partial differential equations. The critical conditions for the onset of instability are found for a broad range of parameter values of the model. It is demonstrated that for the parameter values for which the combustion wave is unstable in the one-step reaction model, the inclusion of the endothermic step can lead to flame stabilization.

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13

Tamaura, Y. "Heat absorption process using endothermic reaction with metal oxide." Progress in Nuclear Energy 29 (January 1995): 159–63. http://dx.doi.org/10.1016/0149-1970(95)00039-m.

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14

Naidenov, V. I. "Hydrodynamic mechanism of spontaneous retardation of an endothermic reaction." Journal of Applied Mechanics and Technical Physics 26, no. 6 (1986): 785–88. http://dx.doi.org/10.1007/bf00919524.

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15

Li, Ming Chun, Yu Sheng Wu, and Ying Tao Song. "The Coupled Heat and Mass Transfers in the Endothermic Chemical Reaction Packed Beds." Advanced Materials Research 402 (November 2011): 436–41. http://dx.doi.org/10.4028/www.scientific.net/amr.402.436.

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Анотація:

According to the assumption of local thermal non-equilibrium and the heat transfer controlled regime, a mathematical model describing the coupling between the heat and mass transfer processes in a porous packed bed with endothermic chemical reactions was established and solved by the alternate dimension implicit method. The calculated results showed that, the profiles of the temperature distributions of the two phases and the solid conversion ratio all decay near the radial boundary wall corresponding to the momentum boundary layer. However, the concentration of the product gas increases near the wall owing to the slower speed layer. The temperatures difference between the gas flow and solid pellets can not be ignored during the study of ore decomposition in the porous packed bed. The reaction features of the packed bed with endothermic reactions under different conditions can be analyzed by the established model.

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16

Kim, Joongyeon, Sun Hee Park, Byung-Hee Chun, Byung Hun Jeong, Jeong Sik Han, and Sung Hyun Kim. "Improvement of the heats of reaction in endothermic reactions of methylcyclohexane with zeolites." Catalysis Today 185, no. 1 (May 2012): 47–53. http://dx.doi.org/10.1016/j.cattod.2011.09.020.

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17

Zhou, Guang Fen, Jie Ren, and Shao Wen Zhang. "Initial Surface Reactions Mechanisms of Atomic Layer Deposition TiO₂ on H/Si(100)-2×1 Surface." Advanced Materials Research 750-752 (August 2013): 1052–56. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.1052.

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The initial surface reaction mechanisms of atomic layer deposition TiO2on H/Si (100 )-2×1 surface using Ti (OCH3)4and H2O as precursors are investigated by density functional theory. The ALD process is divided into two half-reactions, i.e., Ti (OCH3)4and H2O half-reactions. The adsorption energy of Ti (OCH3)4on H/Si (100)2×1 surface is only-2.4 kJ/mol. The overall reaction of Ti (OCH3)4is exothermic, which indicates that Ti (OCH3)4half-reactions are favorable on thermodynamic. Howerver, H2O half-reactions are endothermic and thermodynamically unfavorable.

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18

Fröck, Hannes, Christian Rowolt, Benjamin Milkereit, Michael Reich, Wolfgang Kowalski, Andreas Stark, and Olaf Kessler. "In situ high-energy X-ray diffraction of precipitation and dissolution reactions during heating of Al alloys." Journal of Materials Science 56, no. 35 (October 1, 2021): 19697–708. http://dx.doi.org/10.1007/s10853-021-06548-z.

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AbstractDuring heating of Al alloys, typically a sequence of precipitation and dissolution reactions occurs and the single (partly opposing) reactions superimpose. Differential scanning calorimetry (DSC) is one common technique to analyse the kinetic development of precipitation and dissolution in Al alloys, but the superposition of the exothermic precipitation and endothermic dissolution reactions complicates the DSC signal interpretation, as DSC measures the sum of any heat effect. Synchrotron high-energy X-ray diffraction (HEXRD) allows the kinetic development of phase transformations to be obtained and can support the separation of superimposed DSC signals. HEXRD results from this work offer a new approach to separate part of the superimposed reactions and their kinetic development for the equilibrium phases β-Mg2Si in EN AW-6082 and η-Mg(Zn,Cu,Al)2 in EN AW-7150. Comparing DSC and HEXRD results confirms serious overlap issues. Common DSC evaluation methods alone, using zero crossing between endothermic and exothermic heat flow or peak positions can be misleading regarding individual reaction start and finish temperatures as well as regarding reaction intensities, which can be unambiguously determined by in situ HEXRD.

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19

Harutyunyan, Avetik R., Oleg A. Kuznetsov, Christopher J. Brooks, Elena Mora, and Gugang Chen. "Thermodynamics behind Carbon Nanotube Growth via Endothermic Catalytic Decomposition Reaction." ACS Nano 3, no. 2 (January 29, 2009): 379–85. http://dx.doi.org/10.1021/nn8005569.

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20

Horák, Josef, and Zina Valášková. "Characteristics for evaluating the reactor regime with endothermic reversible reaction." Collection of Czechoslovak Chemical Communications 52, no. 4 (1987): 929–38. http://dx.doi.org/10.1135/cccc19870929.

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Анотація:

Criteria are proposed in the paper for evaluating the reactor regime (with endothermic reversible reaction, heated by radiation of combustion products) from thermodynamic and kinetic points of view. The limiting reactor regimes in which the controlling process is the process kinetics or the heat transfer are defined. The effect of the catalyst activity on the reactor output and the surface temperature of the reaction tube and the effect of heat input power of the reactor radiation section on the conversion and the surface temperature of the tube are discussed. The results are verified on a simplified mathematical model of steam reforming and employed to discuss the selection of the regime of an industrial reactor.

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21

Thierry-Jebali, Nicolas, Rodica Chiriac, and Christian Brylinski. "Evidence of Low Temperature Decomposition of GaN Hetero-Epitaxial Layers on C-Plane Sapphire Surface Characterized by Differential Scanning Calorimetry." Materials Science Forum 778-780 (February 2014): 1185–88. http://dx.doi.org/10.4028/www.scientific.net/msf.778-780.1185.

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This work reports on the characterization of the decomposition of GaN layers epitaxied on c-plane Sapphire substrate by Differential Scanning Calorimetry. Many configurations have been characterized from two different GaN epilayer providers with a large range of doping concentrations from Non-intentionally Doped layers up to 2x1019cm-3. All intentionally doped layers exhibit an endothermic reaction starting at 200-300 °C while the NiD layer thermogram is the same as the blank experiment. XPS and SEM observations demonstrated that the endothermic reaction is related to the GaN decomposition through Threading Dislocation and nanoPipe.

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22

Zhao, Zhanyong, Peikang Bai, Liang Li, Jing Li, Liyun Wu, Pengcheng Huo, and Le Tan. "The Reaction Thermodynamics during Plating Al on Graphene Process." Materials 12, no. 2 (January 21, 2019): 330. http://dx.doi.org/10.3390/ma12020330.

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This research explored a novel chemical reduction of organic aluminum for plating Al on a graphene surface. The thermodynamics of the Al plating reaction process were studied. The Al plating process consisted of two stages: the first was to prepare (C2H5)3Al. In this reaction, the ΔH(enthalpy) was 10.64 kcal/mol, the ΔG(Gibbs free energy) was 19.87 kcal/mol and the ΔS(entropy) was 30.9 cal/(mol·K); this was an endothermic reaction. In the second stage, the (C2H5)3Al decomposed into Al atoms, which were gradually deposited on the surface of the graphene and the Al plating formed. At 298.15 K, the ΔH was −20.21 kcal/mol, the ΔG was −54.822 kcal/mol, the ΔS was 116.08 cal/(mol·K) and the enthalpy change was negative, thus indicating an endothermic reaction.

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23

Xie, Yao Zhong, De Jun Fei, and Ya Gu Dang. "Kinetic Study on the Transport of Chromium(III) by Emulsion Liquid Membrane." Advanced Materials Research 781-784 (September 2013): 2750–57. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.2750.

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The interfacial reactions and thermodynamic properties of the emulsion liquid membrane on separation and concentration of chromium (III) were discussed. Interfacial chemical reaction equations of membrane phase with P204 and mass transfer mechanism of ELM system were determined. The extraction reaction enthalpy is 11.41 kJmol1, while stripping reaction enthalpy is-143.65 kJmol1, were obtained by investigating reaction temperature on the distribution ratio under two different conditions. So extraction is an endothermic process and stripping is an exothermic process. And the main driving force of the separation system is the concentration gradient of hydrogen ion between external and internal phase interface.

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24

Chen, Junjie. "Methanol steam reforming for hydrogen production in microchannel reactors." Chemical Engineering Journal Storage 1, no. 4 (April 26, 2022): 1. http://dx.doi.org/10.29103/cejs.v1i4.6176.

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Анотація:

Many attempts have been made to improve heat transfer for thermally integrated microchannel reforming reactors. However, the mechanisms for the effects of design factors on heat transfer characteristics are still not fully understood. This study relates to a thermochemical process for producing hydrogen by the catalytic endothermic reaction of methanol with steam in a thermally integrated microchannel reforming reactor. Computational fluid dynamics simulations are conducted to better understand the consumption, generation, and exchange of thermal energy between endothermic and exothermic processes in the reactor. The effects of wall heat conduction properties and channel dimensions on heat transfer characteristics and reactor performance are investigated. Thermodynamic analysis is performed based on specific enthalpy to better understand the evolution of thermal energy in the reactor. The results indicate that the thermal conductivity of the channel walls is fundamentally important. Materials with high thermal conductivity are preferred for the channel walls. Thermally conductive ceramics and metals are well-suited. Wall materials with poor heat conduction properties degrade the reactor performance. Reaction heat flux profiles are considerably affected by channel dimensions. The peak reaction heat flux increases with the channel dimensions while maintaining the flow rates. The change in specific enthalpy is positive for the exothermic reaction and negative for the endothermic reaction. The change in specific sensible enthalpy is always positive. Design recommendations are made to improve thermal performance for the reactor.

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25

Chen, Junjie. "Methanol steam reforming for hydrogen production in microchannel reactors." Chemical Engineering Journal Storage 1, no. 4 (April 26, 2022): 1. http://dx.doi.org/10.29103/cejs.v1i4.6176.

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Анотація:

Many attempts have been made to improve heat transfer for thermally integrated microchannel reforming reactors. However, the mechanisms for the effects of design factors on heat transfer characteristics are still not fully understood. This study relates to a thermochemical process for producing hydrogen by the catalytic endothermic reaction of methanol with steam in a thermally integrated microchannel reforming reactor. Computational fluid dynamics simulations are conducted to better understand the consumption, generation, and exchange of thermal energy between endothermic and exothermic processes in the reactor. The effects of wall heat conduction properties and channel dimensions on heat transfer characteristics and reactor performance are investigated. Thermodynamic analysis is performed based on specific enthalpy to better understand the evolution of thermal energy in the reactor. The results indicate that the thermal conductivity of the channel walls is fundamentally important. Materials with high thermal conductivity are preferred for the channel walls. Thermally conductive ceramics and metals are well-suited. Wall materials with poor heat conduction properties degrade the reactor performance. Reaction heat flux profiles are considerably affected by channel dimensions. The peak reaction heat flux increases with the channel dimensions while maintaining the flow rates. The change in specific enthalpy is positive for the exothermic reaction and negative for the endothermic reaction. The change in specific sensible enthalpy is always positive. Design recommendations are made to improve thermal performance for the reactor.

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26

Omran, Mamdouh, Timo Fabritius, Yaowei Yu, and Guo Chen. "Thermal and Mass Spectroscopic Analysis of BF and BOF Sludges: Study of Their Behavior under Air and Inert Atmosphere." Metals 10, no. 3 (March 19, 2020): 397. http://dx.doi.org/10.3390/met10030397.

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Анотація:

Differential thermal analysis (DTA), thermogravimetry (TG), and mass spectrometry (MS) were used to study the thermal behavior of the blast furnace (BF) and basic oxygen furnace (BOF) sludges generated from the iron-making industry. The results indicated that under air atmosphere the two types of sludge are different in their thermal behavior. In BF sludge, the exothermic carbon gasification (CO/CO2) reaction dominated the process, while in BOF sludge, the significant reaction occurred at 755 °C and was associated with a slight mass gain owing to the partial oxidation of Fe3O4 to Fe2O3. Under inert atmosphere, the thermal behavior of both BF and BOF sludges were dominated by a reduction reaction. In BF sludge, the endothermic reactions ranged from 785 to 1115 °C due to the reduction of iron oxides as follows: Fe2O3 → Fe3O4 → FeO → Fe. A total mass loss of about 27.78% was observed in the TG curve. While in BOF sludge, the endothermic peaks corresponded to magnetite reduction to iron (Fe). The overall mass loss of the BOF was approximately 16.92%. The mass spectrum of gases evolution for both BF and BOF sludges revealed that CO/CO2 gases were released from the sludges.

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27

Watt, Simon, Zhejun Huang, and Harvinder Sidhu. "Analysis of two-dimensional combustion waves arising in the presence of a competitive endothermic reaction." ANZIAM Journal 60 (July 15, 2019): C95—C108. http://dx.doi.org/10.21914/anziamj.v60i0.14065.

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Анотація:

We consider a system of reaction-diffusion equations describing combustion dynamics. The reaction is assumed to undergo two competitive reactions, one which is exothermic and one which is endothermic. The one-dimensional model has been shown to exhibit complex behaviour, from propagating combustion waves with a constant speed to period doubling cascades and the possibility of chaotic wave speeds. In this study, we extend the combustion model from one to two dimensions by exploring a model of an insulated strip with no heat loss and axially symmetric spread. In particular, we compare and contrast the behaviour of the systems in one and two dimensions. References J. D. Buckmaster and G. S. S. Ludford. Theory of Laminar Flames. Cambridge Monographs on Mechanics and Applied Mathematics. Cambridge University Press, 1982. doi:10.1017/CBO9780511569531. V. Gubernov, A. Kolobov, A. Polezhaev, H. Sidhu, and G. Mercer. Period doubling and chaotic transient in a model of chain-branching combustion wave propagation. P. Roy. Soc. A Math. Phy., 466:27472769, 2010. doi:10.1098/rspa.2009.0668. A. Hmaidi, A. C. McIntosh, and J. Brindley. A mathematical model of hotspot condensed phase ignition in the presence of a competitive endothermic reaction. Combust. Theor. Model., 14:893920, 2010. doi:10.1080/13647830.2010.519050. G. N. Mercer and R. O. Weber. Combustion waves in two dimensions and their one-dimensional approximation. Combust. Theor. Model., 1:157165, 1997. doi:10.1088/1364-7830/1/2/002. J. J. Sharples, H. S. Sidhu, A. C. McIntosh, J. Brindley, and V. V. Gubernov. Analysis of combustion waves arising in the presence of a competitive endothermic reaction. IMA J. Appl. Math., 77:1831, 2012. doi:10.1093/imamat/hxr072. S. D. Watt, R. O. Weber, H. S. Sidhu, and G. N. Mercer. A weight-function approach for determining watershed initial conditions for combustion waves. IMA J. Appl. Math., 62:195206, 1999. doi:10.1093/imamat/62.2.195.

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28

Quyen, Nguyen Duc Vu, Tran Ngoc Tuyen, Dinh Quang Khieu, Ho Van Minh Hai, Dang Xuan Tin, and Kiyoshi Itatani. "Oxidation of dibenzothiophene using the heterogeneous catalyst of tungsten-based carbon nanotubes." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 68–77. http://dx.doi.org/10.1515/gps-2017-0189.

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Abstract Highly effective tungsten-based carbon nanotubes (W/CNT) were synthesized and used as a heterogeneous catalyst for the oxidation of dibenzothiophene (DBT) with the oxidant H2O2. The obtained materials were characterized by modern methods. The Langmuir–Hinshelwood kinetics model described the precursor mechanism of the reaction well through an intermediate compound. The low activation energy showed that the reaction was mainly controlled by diffusion. The positive activation enthalpy proved the endothermic nature of the activation process, and this process did not alter the inside structure of the catalyst. The thermodynamic parameters of the reaction were determined, which implied that the oxidation was endothermic and spontaneous at 303 K. The more negative values of the Gibbs free energy from 283 to 323 K confirmed that the reaction was more favorable at high temperatures. The stability and activity of catalyst were retained after three reaction cycles.

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29

Arsene, Ion, Eduard Coropceanu, and Viorica Purcel. "DFT study of condensation mechanisms of 4-pyridinecarboxaldehyde with o-, m-, p-aminobenzoic acids." Acta et commentationes: Ştiinţe Exacte şi ale Naturii 13, no. 1 (November 2022): 122–32. http://dx.doi.org/10.36120/2587-3644.v13i1.122-132.

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It was theoretically studied the mechanism of the condensation reaction of 4-pyridinecarbo\-xaldehyde with o-, m- and p-aminobenzoic acids. Theoretical calculations represent a primary advantage in studying these reactions, along with the determination of a wide range of molecular properties. The studied reactions take place in two stages, each stage is accompanied by a transition state and for each stage it is calculated the activation energy. Thermodynamically speaking, all reactions are endothermic and the most convenient from an energetic point of view is the reaction for obtaining 4-(pyridine-3-yl-methylene amino) benzoic acid in methanol with an energy value of 9.98 kcal/mol.

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30

Cao, Jianwei, Yanan Wu, Haitao Ma, Zhitao Shen, and Wensheng Bian. "Dynamics and kinetics of the Si(1D) + H2/D2 reactions on a new global ab initio potential energy surface." Physical Chemistry Chemical Physics 23, no. 10 (2021): 6141–53. http://dx.doi.org/10.1039/d0cp05540a.

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31

Thirabunjongcharoen, Sasinun, and Pattaraporn Kim-Lohsoontorn. "Effect of impurity on thermally self-sustained double reactor coupling hydrogen production from glycerol reforming and methanol production from carbon dioxide and hydrogen." E3S Web of Conferences 155 (2020): 01004. http://dx.doi.org/10.1051/e3sconf/202015501004.

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Thermally self-sustained double reactor (TSSDR) operating without external heat source consists of dual channels for endothermic and exothermic reactions. Hydrogen (H2) is produced from wasted glycerol by aqueous-phase glycerol reforming (APGR) at 200-250 ºC and 20-25 bar while carbon dioxide (CO2) is a by-product. Produced H2 and CO2 are used as raw materials for methanol synthesis (MS) at 200-250 ºC and 50-80 bar. Methanol synthesis and glycerol reforming occur at inner and outer channels of TSSDR, respectively. The TSSDR is fully packed with catalyst. Generated heat of exothermic reaction is sufficient for endothermic reaction. Main products of glycerol reforming in gas phase are H2 and CO2 while CO and CH4 are by-products. All products in gas phase are totally recycled as a feed stream for exothermic channel. CO and CH4 in feed reduce CO2 conversion and methanol yield in MS. The effect of impurities in glycerol feed stream also influences with hydrogen production in APGR. Especially, methanol, which is an impurity in glycerol feed obtained from biodiesel production, significantly reduces glycerol conversion in TSSDR.

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32

Forbes, Lawrence K. "Thermal solitons: travelling waves in combustion." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 469, no. 2150 (February 8, 2013): 20120587. http://dx.doi.org/10.1098/rspa.2012.0587.

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A competitive reaction system is considered, under which some chemical reagent decays by means of two simultaneous chemical reactions to form two separate inert products. One reaction is exothermic, and the other is endothermic. The governing equations for the model are presented, and a weakly nonlinear theory is then generated using the method of strained coordinates. Travelling-wave solutions are possible in the model, and the temperature is found to have a classical sech-squared profile. The stability of these moderate-amplitude temperature solitons is confirmed both analytically and numerically.

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33

Wang, Keyun, and Michael D. Sacks. "Mullite Formation by Endothermic Reaction of alpha-Alumina/Silica Microcomposite Particles." Journal of the American Ceramic Society 79, no. 1 (January 1996): 12–16. http://dx.doi.org/10.1111/j.1151-2916.1996.tb07874.x.

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34

Zhang, Xiangwen, Enhui Xing, Gexin Chen, and Zhentao Mi. "Monomolecular endothermic reaction of n-decane catalyzed by HZSM-5 films." Reaction Kinetics and Catalysis Letters 89, no. 2 (August 2006): 237–45. http://dx.doi.org/10.1007/s11144-006-0133-0.

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35

Van Der Vaart, D. R., and H. R. Van Der Vaart. "Use of a second endothermic reaction to desensitize a tubular reactor." AIChE Journal 37, no. 2 (February 1991): 225–32. http://dx.doi.org/10.1002/aic.690370208.

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36

van der Vaart, D. R., and H. R. van der Vaart. "Use of sensitivity analysis to describe an endothermic/exothermic reaction system." AIChE Journal 38, no. 3 (March 1992): 461–65. http://dx.doi.org/10.1002/aic.690380315.

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37

Singare, Pravin U., Akmal L. Khan Mohammed, and N. N. Dixit. "Comparative Study of Uni-Univalent H⁺/Na⁺ and Uni-Bivalent H⁺/Ca²⁺ Ion Exchange Reactions Using Nuclear Grade Resin Indion-223." International Letters of Chemistry, Physics and Astronomy 33 (May 2014): 127–35. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.33.127.

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The present paper deals with the ion exchange equilibrium studies of uni-univalent and uni-bivalent ion exchange reactions using nuclear grade anion exchange resin Indion-223 in H+ form towards Na+ and Ca2+ ions in the solution. It was observed that with rise in temperature the equilibrium constants K values for H+/Na+ uni-univalet ion exchange reaction increases from 0.01389 to 0.01855. Similarly for H+/Ca2+ uni-bivalet ion exchange reaction the equilibrium constants K values increases from 0.000397 to 0.000639. The increase in equilibrium constant values with rise in temperature indicate endothermic ion exchange reactions having the enthalpy change values of 25.55 and 38.92 kJ/ mol respectively.

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38

Singare, Pravin U., Akmal L. Khan Mohammed, and N. N. Dixit. "Comparative Study of Uni-Univalent H<sup>+</sup>/Na<sup>+</sup> and Uni-Bivalent H<sup>+</sup>/Ca<sup>2+</sup> Ion Exchange Reactions Using Nuclear Grade Resin Indion-223." International Letters of Chemistry, Physics and Astronomy 33 (May 11, 2014): 127–35. http://dx.doi.org/10.56431/p-66md9e.

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Анотація:

The present paper deals with the ion exchange equilibrium studies of uni-univalent and uni-bivalent ion exchange reactions using nuclear grade anion exchange resin Indion-223 in H+ form towards Na+ and Ca2+ ions in the solution. It was observed that with rise in temperature the equilibrium constants K values for H+/Na+ uni-univalet ion exchange reaction increases from 0.01389 to 0.01855. Similarly for H+/Ca2+ uni-bivalet ion exchange reaction the equilibrium constants K values increases from 0.000397 to 0.000639. The increase in equilibrium constant values with rise in temperature indicate endothermic ion exchange reactions having the enthalpy change values of 25.55 and 38.92 kJ/ mol respectively.

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39

Wee, Wilson, Harvinder Sidhu, Jason Sharples, Isaac Towers, and Vladimir Gubernov. "Properties of reaction fronts in a non-adiabatic two stage exothermic-endothermic competitive reaction scheme." ANZIAM Journal 54 (October 10, 2013): 646. http://dx.doi.org/10.21914/anziamj.v54i0.6302.

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40

Feng, Yu, Silong Zhang, Kun Wu, Jiang Qin, Yong Cao, and Hongyan Huang. "Numerical investigation of distribution of reaction rate during convective heat transfer with endothermic chemical reaction." International Communications in Heat and Mass Transfer 83 (April 2017): 1–7. http://dx.doi.org/10.1016/j.icheatmasstransfer.2016.12.021.

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41

Ito, Naotsugu, Toshikatsu Hakuta, Hiroshi Yoshitome, and Teiriki Tadaki. "Reaction progress mechanism in a rotary drum reactor of solid particles with an endothermic reaction." KAGAKU KOGAKU RONBUNSHU 11, no. 6 (1985): 721–28. http://dx.doi.org/10.1252/kakoronbunshu.11.721.

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42

Wang, Y., and C. M. Kinoshita. "Temperature Field and Reaction Zones in Biomass Gasification." Journal of Solar Energy Engineering 113, no. 4 (November 1, 1991): 224–27. http://dx.doi.org/10.1115/1.2929966.

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A method used to measure and validate the temperature field in an experimental downdraft biomass gasifier and reformulate the discrete test data into continuous mathematical functions is described. The reformulated temperature field is analyzed to identify different reaction zones within the gasifier. Distinct endothermic and exothermic regions, separated by rather complicated boundaries, are found.

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43

Dong, Mao Jin, Ran Fang, Yu Qing Xiong, Duo Shu Wang, Ji Zhou Wang, Chen Li, and Ling Zhang. "Reaction Mechanism of Atomic Layer Deposition of Al on the Si (100) Surface: A Density Functional Theory Study." Advanced Materials Research 941-944 (June 2014): 1283–87. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.1283.

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Using H2 and Al (CH3)3(TMA) as precursor, we investigated the atomic layer deposition mechanism of the metal Al on Si (100) surface by density functional theory. The reaction process comprises two half-reaction depositions: TMA "half-reaction" includes I and II on the H blunt reaction surface; H2 "half-reaction" includes the subsequent reaction Ⅲ and Ⅳ. In the TMA half reaction process, trimethyl aluminum first molecularly adsorbed in the active site of H*-Si9H12-H* to form a stable complex in the form of chemical adsorption state. Potential curves show that at 298 K, adsorption energy is -2.26kJ/mol, with respect to the chemical adsorption state, the activation barrier energy is 124.72kJ/mol, and finally the whole exothermic reaction energy is 41.4kJ/mol. After H2 half reaction, the bond length between Al-Si can be considered equal; two Al-C bonds become relatively stable molecular structure. The adsorption energy is -0.10kJ/mol at 298 K, and the activation barrier energy 189.15kJ/mol. The results show that two half-reaction process mechanism is similar, TMA endothermic reaction needs more energy to be carried out under heating conditions ; endothermic and exothermic reaction energy is basic balance, the activation energy is large, so the reaction is the best using ionized gas to be carried out.

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44

Horák, Josef, and Simona Červenková. "The Effect of Interparticle Heat and Mass Transfer on the Behaviour of Catalytic Adiabatic Reactors with Endothermic Reactions. I. The Reactor Model." Collection of Czechoslovak Chemical Communications 57, no. 9 (1992): 1888–98. http://dx.doi.org/10.1135/cccc19921888.

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The effect of gas-particle heat and mass transfer on the reaction rate and the catalyst temperature in an adiabatic reactor with strongly endothermic reaction was studied using a mathematical model. It was found that subcooling of the catalyst surface against the reaction mixture is the prevailing phenomenon affecting the effectiveness factor and the longitudinal profile of the reaction rate.

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45

Broadbridge, P., B. H. Bradshaw-Hajek, and D. Triadis. "Exact non-classical symmetry solutions of Arrhenius reaction–diffusion." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, no. 2184 (December 2015): 20150580. http://dx.doi.org/10.1098/rspa.2015.0580.

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Exact solutions for nonlinear Arrhenius reaction–diffusion are constructed in n -dimensions. A single relationship between nonlinear diffusivity and the nonlinear reaction term leads to a non-classical Lie symmetry whose invariant solutions have a heat flux that is exponential in time (either growth or decay), and satisfying a linear Helmholtz equation in space. This construction also extends to heterogeneous diffusion wherein the nonlinear diffusivity factorizes to the product of a function of temperature and a function of position. Example solutions are given with applications to heat conduction in conjunction with either exothermic or endothermic reactions, and to soil–water flow in conjunction with water extraction by a web of plant roots.

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46

Ghosal, Partha S., and Ashok K. Gupta. "An insight into thermodynamics of adsorptive removal of fluoride by calcined Ca–Al–(NO3) layered double hydroxide." RSC Advances 5, no. 128 (2015): 105889–900. http://dx.doi.org/10.1039/c5ra20538g.

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Анотація:

A framework for determination of thermodynamic equilibrium constant and Gibbs free surface energy change was presented. The interactive effect of temperature on adsorption process was addressed by RSM. Endothermic, spontaneous reaction was observed.

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47

KOJIMA, Noboru, and Iwane FUJII. "A Measurement Method of Endothermic and Exothermic Reaction on Chemical Heat Storage." Journal of the Japan Society for Precision Engineering 58, no. 12 (1992): 1989–94. http://dx.doi.org/10.2493/jjspe.58.1989.

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48

Li, Haiyue, Huangwei Zhang, and Zheng Chen. "Effects of endothermic chain-branching reaction on spherical flame initiation and propagation." Combustion Theory and Modelling 23, no. 3 (December 9, 2018): 496–514. http://dx.doi.org/10.1080/13647830.2018.1555338.

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49

Na, J. H. "The Origin of a Two-Stage Endothermic Reaction in Zr36Ti24Be40 Metallic Glass." Metals and Materials International 14, no. 5 (October 23, 2008): 553–57. http://dx.doi.org/10.3365/met.mat.2008.10.553.

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50

Jeyabarathi, Ponraj, Lakshmanan Rajendran, Michael E. G. Lyons, and Marwan Abukhaled. "Theoretical Analysis of Mass Transfer Behavior in Fixed-Bed Electrochemical Reactors: Akbari-Ganji’s Method." Electrochem 3, no. 4 (October 17, 2022): 699–712. http://dx.doi.org/10.3390/electrochem3040046.

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Анотація:

The theoretical model for a packed porous catalytic particle of the slab, cylindrical, and spherical geometries shape in fixed-bed electrochemical reactors is discussed. These particles have internal mass concentration and temperature gradients in endothermic or exothermic reactions. The model is based on a nonlinear reaction–diffusion equation containing a nonlinear term with an exponential relationship between intrinsic reaction rate and temperature. The porous catalyst particle’s concentration is obtained by solving the nonlinear equation using Akbari-Ganji’s method. A simple and closed-form analytical expression of the effectiveness factor for slab, cylindrical, and spherical geometries was also reported for all values of Thiele modulus, activation energy, and heat reaction. The accordance with results of a reliable numerical method shows the good accuracy that their approximate solution yields.

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