Coupling thermal-chemical

The numerical jet model [9-11] is based on the numerical solution of the time-dependent, compressible flow conservation equations for total mass, energy, momentum, and chemical species number densities, with appropriate in-flow/outfiow open-boundary conditions and an ideal gas equation of state. In the reactive simulations, multispecies temperature-dependent diffusion and thermal conduction processes [11, 12] are calculated explicitly using central difference approximations and coupled to chemical kinetics and convection using timestep-splitting techniques [13]. Global models for hydrogen [14] and propane chemistry [15] have been used in the 3D, time-dependent reactive jet simulations. Extensive comparisons with laboratory experiments have been reported for non-reactive jets [9, 16] validation of the reactive/diffusive models is discussed in [14]. 

Abstract A fully coupled model of hygro-thermo-chemo-mechanical phenomena in concrete is presented. A mechanistic approach has been used to obtain the governing equations, by means of the hybrid mixture theory. The final equations are written in terms of the chosen primary and internal variables. The model takes into account coupling between hygral, thermal, chemical phenomena (hydration or dehydration), and material deformations, as well as changes of concrete properties, caused by these processes, e.g. porosity, permeability, stress-strain relation, etc. 

The governing equations (1) - (10) are completed by an appropriate set of state and thermodynamic equations as well as boundary conditions and constitutive relationships. The latter ones express some inherent couplings between chemical and hygro-thermal phenomena and medium deformations. 

Poly(dimethylsiloxane) was the backbone of this growing industry. The unprecedented inertness of this polymer under thermal, chemical, and biological environments, coupled with its unique physical behavior, led to a myriad of commercial applications. Its uses include mechanical applications, in which stability in hostile environments was the desired attribute surface treatments, in which low surface energy was the important feature and cosmetic and biomedical applications, in which the biological inertness of the material was exploited. During this period, this new and healthy industry was expanding in all directions. 

Lichtner (2001) developed the computer code FLOTRAN, with coupled thermal-hydrologic-chemical (THC) processes in variably saturated, nonisothermal, porous media in 1, 2, or 3 spatial dimensions. Chemical reactions included in FLOTRAN consist of homogeneous gaseous reactions, mineral precipitation/dissolution, ion exchange, and adsorption. Kinetic rate laws and redox... 

The flow of groundwater in a sedimentary basin results from the combined influence of the different driving forces for groundwater flow (mechanical, thermal, chemical and electrical driving forces) and the hydraulic conductivity of the subsurface. The transport of grovmdwater, heat and electricity, the mass transport of chemical components and the deformation of the solid part of the subsurface are coupled processes. 

The thermal effects of solar and atmospheric radiation have been studied using mathematical models, generally by solving the radiative transfer equations which we have just described (e.g., Ramanathan, 1976). The most elaborate models, particularly those with fine spectral resolution, require rather large computing resources, and cannot be coupled with chemical or dynamical models using present computers unless they are greatly simplified. 

Batteries exposed to certain abusive conditions may experience thermal runaway - a series of coupled exothermic chemical reactions involving metallic lithium, lithium dithionite and possibly sulfur, resulting in the formation of sulfides. At the elevated temperatures resulting from these reactions, these products may further react with the carbon in the cathode to form carbon dioxide (CO2) and carbon disulfide (CS2). Carbon... 

Abstract This paper introduces the current state of research on the coupled Thermal-Hydraulic-Mechanical-Chemical (THMC) processes in geo-materials and applications for geotechnical and geo-environmental engineering in China. The paper puts equal emphasis on both the achievements of experimental results for fundamental studies, and the applications in rock mechanics and foundation engineering, tunnel engineering, geothermal mining, unsaturated soil and dynamic consolidation. At the end, it presents a model for chemical mining. 

Painter, S.L, P.C. Lichmer, and M.S. Seth. MULTIFLO User s Manual MULTIFLO Version 1.5-Two-Phase Nonisothermal Coupled Thermal-Hydrologic-Chemical Flow Simulator. Revision 3. Change 0. San Antonio. TX Center for Nuclear Waste Regulatory Analyses. 2001. 

The DST is the second underground thermal test to be carried out in the Exploratory Studies Facility (ESF) at Yucca Mountain, Nevada. The purpose of the test is to evaluate the effect of coupled thermal, hydrological, chemical, and mechanical processes that take place in unsaturated fractured tuff over a range of temperatures (approximately 25°C to 200°C). The DST heaters were activated on December 3,1997, with a planned period of 4 years of heating, followed by 4 years of cooling. After just over 4 years, the heaters were switched off and since that time the system has been slowly cooling. 

Since the model involves the Komine s theoretical model for evaluating swelling pressure in saturation, it has the potential to include the effects of chemical change in bentonite and pore water. Using this model, fully coupled thermal, hydraulic, mechanical and chemical analysis can be conducted in the future. 

Despite their separation, the two parts of the system influence each other so that an increase of water level in one causes an increase of the water level in the other and vice versa. This reciprocal coupling between different types of quantities, mechanical, thermal, chemical, electrical, etc., is central to thermodynamics and matter dynamics. We will go into this more deeply in Chap. 9 when we have acquired the necessary background. 

Achieving desirable resolution, however, is a complicated process that extends beyond the simple addition of an UV absorber. Resolution may be affected by what is essentially a coupled optical-chemical-thermal process that occurs during polymerization in the pSL environment. Initial photolysis of the photo-initiators... 

When exposed to high temperatures and fire, FRP composites experience complex changes in material states involving the interaction of thermal, chemical, physical, mechanical, and structural phenomena. Modeling and predicting aU the coupled responses of FRP stmctures is therefore a complex task. By treating independently only one or two of these phenomena in each model, however, the task becomes more reasonable. The thermal phenomena (heat transfer, temperature distribution, etc.) are mainly determined by the thermophysical properties of the material and the thermal boundary conditions, while the mechanical and stmctural phenomena... 

Factor analytical methods can clearly be coupled to chemical intuition to enhance the understanding of processes such as controlled pyrolysis. The real power of the use of factor-analytical methods in the analysis of complex chemical phenomena, such as the pyrolysis of ruhher hlends, lies in the ability to gain molecular chemical insights that might otherwise he obscured. The belief that temperature control and knowledge of the process temperature is of major importance in avoiding thermal decomposition in a polymer blending process is confirmed by these workers. Further use of these mathematical methods could help discover why nominally identical materials from different batches are, in fact, very different in their performance in actual use. 

In this Chapter, the theoretical models for non-equilibrium chemical kinetics in multi-component reacting gas flows are proposed on the basis of three approaches of the kinetic theory. In the frame of the one-temperature approximation the chemical kinetics in thermal equilibrium flows or deviating weakly from thermal equilibrium is studied. The coupling of chemical kinetics and fluid dynamics equations is considered in the Euler and Navier-Stokes approximations. Chemical kinetics in vibrationaUy non-equilibrium flows is considered on the basis of the state-to-state and multi-temperature approaches. Different models for vibrational-chemical coupling in the flows of multi-component mixtures are derived. The influence of non-equilibrium distributions on reaction rates in the flows behind shock waves and in nozzle expansion is demonstrated. 

Various thermochemical water-splitting processes have been proposed to address hydrogen production on a large scale. Most of these cycles utilize a high-temperature heat source for rapid chemical kinetics and high conversion efficiencies. In the thermochemical processes, a set of coupled, thermally-driven chemical reactions decompose water into H2 and O with various intermediate regents. All reagents returned within the cycle and... 

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