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A GENERIC THERMODYNAMIC EQUILIBRIUM MODEL-BASED FRAMEWORK FOR BIOMASS GASIFICATION PROCESSES

A GENERIC THERMODYNAMIC EQUILIBRIUM MODEL-BASED FRAMEWORK FOR BIOMASS GASIFICATION PROCESSES

In step 3, the thermodynamic equilibrium model is used to represent the gasification process as shown in Table-2. Two main general reactions that might occur to the feedstock during the gasification process based on the reactant used either using air or steam. The reaction occurs in the downdraft gasifier is using air as reactant and the reaction occurs in the fluidized bed gasifier is employing steam as reactant for gasification. The chemical formula of the selected biomass is determined from the data of ultimate analysis. In the ultimate analysis, the composition in mass fraction of element in the materials which includes the composition of carbon, hydrogen, nitrogen, sulphur and oxygen are given as shown in Figure-2. This information is then used to calculate the chemical formula using Equations (1) - (2). For example, the calculation of general biomass chemical formula C n H a O b is determined
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A sub-grid, mixture fraction-based thermodynamic equilibrium model for gas phase combustion in FIRETEC: development and results

A sub-grid, mixture fraction-based thermodynamic equilibrium model for gas phase combustion in FIRETEC: development and results

Computational costs constrain grid refinement in HIGRAD/ FIRETEC, limiting resolution to length scales on the order of 1 m. Since the physics and chemistry of combustion occur at length scales that are not resolved in HIGRAD/FIRETEC, it becomes necessary to utilise sub-grid models to account for these phenomena. To facilitate the application of the mixture–fraction model to HIGRAD/FIRETEC, a new sub-grid model was con- ceived and developed in order to account for the fact that volatiles and oxygen are not homogeneously distributed within the cells. The products of solid pyrolysis are a mixture of gases includ- ing combustible hydrocarbon-like species. It is assumed that these combustible gases reside within spherical pockets, as illus- trated in 2-D by the solid circle in Fig. 1, which is a simplified cartoon describing the mixing and reaction zone for gas phase chemical reactions. Part of the volume of the hydrocarbon pocket mixes with a volume of surrounding air and this mixture reacts to form product chemical species and produce a heat of reaction. It is assumed that the combustible gases from the hydrocarbon pocket and the volume of air mix rapidly to form a homogenous mixture at each numerical time step. The volume of this mix- ing layer around the spherical pockets depends on the radius of the pocket, r, and the length, l + l · a, over which air and com- bustible gases mix, as depicted in Fig. 1 by the lightly shaded region. The pocket parameters also define the ratio of the volume of pure hydrocarbons from the pocket to the volume of air that
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Energy recovery from human faeces via gasification : a thermodynamic equilibrium modelling approach

Energy recovery from human faeces via gasification : a thermodynamic equilibrium modelling approach

Non-sewered sanitary systems (NSS) are emerging as one of the solutions to poor sanitation because of the limitations of the conventional flush toilet. These new sanitary systems are expected to safely treat faecal waste and operate without external connections to a sewer, water supply or energy source. The Nano Membrane Toilet (NMT) is a unique domestic-scale sanitary solution currently being developed to treat human waste on-site. This toilet will employ a small-scale gasifier to convert human faeces into products of high energy value. This study investigated the suitability of human faeces as a feedstock for gasification. It quantified the recoverable exergy potential from human faeces and explored the optimal routes for thermal conversion, using a thermodynamic equilibrium model. Fresh human faeces were found to have approximately 70–82 wt.% moisture and 3–6 wt.% ash. Product gas resulting from a typical dry human faeces (0 wt.% moisture) had LHV and exergy values of 17.2 MJ/kg and 24 MJ/kg respectively at optimum equivalence ratio of 0.31, values that are comparable to wood biomass. For suitable conver- sion of moist faecal samples, near combustion operating conditions are required, if an external energy source is not supplied. This is however at 5% loss in the exergy value of the gas, provided both thermal heat and energy of the gas are recovered. This study shows that the maximum recoverable exergy poten- tial from an average adult moist human faeces can be up to 15 MJ/kg, when the gasifier is operated at optimum equivalence ratio of 0.57, excluding heat losses, distribution or other losses that result from operational activities.
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Polynyas in a dynamic-thermodynamic sea-ice model

Polynyas in a dynamic-thermodynamic sea-ice model

In the first flux polynya model, proposed by Pease (1987), the frazil ice inside the polynya is immediately transferred to the edge of the consolidated ice, where it piles up. The model by Ou (1988), and later models, assume a constant (and finite) velocity for the frazil ice, but this must always be greater than the velocity of the consolidated ice. In reality the frazil ice drifts faster than the consolidated ice because frazil ice, near or at the surface, experiences less water shear stress than the consolidated ice. The water velocity inside the polynya is also different from that under the consolidated ice, but this can be difficult to account for in a simplified setup. Finally the initial ice pack may not drift at the (local) free drift speed, as the wind that creates the polynya is non- uniform and may be weaker further off shore. Islands and other coast lines may also slow down the drift of the initial ice pack.
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THERMODYNAMIC EQUILIBRIUM PREDICTION FOR NATURAL GAS DRY REFORMING IN THERMAL PLASMA REFORMER

THERMODYNAMIC EQUILIBRIUM PREDICTION FOR NATURAL GAS DRY REFORMING IN THERMAL PLASMA REFORMER

conducted. In our opinion, the thermodynamic equi- librium prediction should be done to forecast an op- timal operating condition and some other working conditions for a thermal plasma reformer. The ex- perimental procedure for the test plan is then predefined with reference to the predicted results. Without ex- act knowledge about possible reactions in CH 4 dry

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Partial equilibrium model – beef

Partial equilibrium model – beef

The significant increases in the import and export volumes are modified by the development of the rate between the domestic and foreign price as well as by the development of domestic consumption, as confirmed by the outputs of the estimated model. Both categories have a significantly positive param- eter of the time vector, whilst import would also be increased at an increase in the domestic demand as well as at an increase in the domestic processed meat price, which would make domestic products less competitive. Proven in the export equation were the standard economic principles, which increase export at increasing the rate of the export price compared with the domestic processed meat price. The total domestic offer of the meat processing sector is, ac- cording to the model outputs, strongly and positively influenced mainly by the realized import. The meat processing plant price is over-proportionally influ- enced by the farmer price and sub-proportionally pulled by the consumer price. The function of do- mestic consumption has the expected development, because an increase in the consumer price would induce a significant decrease in demand, and on the contrary, increasing income would slightly increase the demand. From the point of the consumer price, statistically significant influences of the processed meat price, the price of chicken and foreign trade prices were observed, whilst the industrial producer price increases the consumer price, similarly to the price of chicken, from which it is possible to assume the competitive relation between both types of meat.
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The Thermodynamic Model on Paraffin Wax Deposition Prediction

The Thermodynamic Model on Paraffin Wax Deposition Prediction

In process of crude oil production and transportation, wax and other solid deposition issues have a significant impact on oilfield production. Solid precipitation not only reduces the production ef- ficiency and increases the cost of production. Therefore, there is a need to study the rate of paraf- fin wax deposition and cloud point temperature in order to guide the oil field control the paraffin wax deposition. In this paper, we use the Flory theory of polymer solution to correct the liquid ac- tivity coefficients, and regular solution theory to correct for the non ideality of the solid mixture, and we consider the impact of isoparaffin. Finally, thermodynamic model is established. The ac- tual example calculation shows that the forecast results of this model are more accurate.
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Return to equilibrium in the XY-model

Return to equilibrium in the XY-model

If the PN E A~ is a norm bounded sequence of self-adjoint operators in A~ and {lPN ' A]} converges strongly for each a strongly continuous *-automorphism group T~ is the closure in A~ X [r]

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Equilibrium and Thermodynamic Studies of Cesium Adsorption on Natural Vermiculite and Optimization of Operation Conditions

Equilibrium and Thermodynamic Studies of Cesium Adsorption on Natural Vermiculite and Optimization of Operation Conditions

The present work deals with a series of experiments to assess the optimum conditions of vermiculite for the removal of cesium from aqueous solutions. The amounts adsorbed at equilibrium sorption were measured at different pHs and temperatures. The adsorption isotherms at varying solution temperatures and pHs were measured, and suitable model equations were tried to fit the experimental data

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Adsorption of Congo Red by Ni/Al-CO3: Equilibrium, Thermodynamic and Kinetic Studies

Adsorption of Congo Red by Ni/Al-CO3: Equilibrium, Thermodynamic and Kinetic Studies

Temkin adsorption isotherm model is usually chosen to evaluate the adsorption potentials of an adsorbent for the adsorbate from an experimental data. This model gives the mechanism and adsorption capacity of an adsorbate in a sorption process. By plotting q e against Inc e, the Temkin constants A and B where calculated from the slope and intercept. The constants A and B are 1.377 and 2.0498 respectively while the correlation coefficient value was 0.9689, indicating that the adsorption process is physical.

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Equilibrium, kinetic and thermodynamic studies of silarhodanine tautomers by highly CBS Q method

Equilibrium, kinetic and thermodynamic studies of silarhodanine tautomers by highly CBS Q method

Heterocyclic compounds are organic compounds that contain a ring structure containing atoms in addition to carbon, such as sulfur, oxygen or nitrogen as part of the ring. A heterocyclic compound is a cyclic compound which has atoms of at least two different elements of its ring(s). Heterocyclic compounds can be spotted in hemoglobin, penicillin, vitamins (C, B6 and B12), alkaloids, flavonoids and DNA structure. The prototropic tautomerizm and rotamerization of heterocyclic compounds are including, in particular, biologically active compounds, are of great importance in many areas of chemistry and biochemistry. The term tautomerizm refers to a compound existing in an equilibrium between two or more isomeric form called tautomers [1,2]. The tautomers of Rhodanine (2-thioxothiazolidin-4-one) and its derivatives have showed many biological activities including antibacterial, antiviral, antidiabetical and anti-inflammatory action [3-7]. The molecular properties including the Gibbs free energy of salvation of doxorubicin were investigated by computational methodology [8]. The tautomerizm of substituted thiazolidine and oxazolidine heterocycles were studied theoretically at the B3LYP/6- 311G(2d,p) level. The thermodynamic parameters for the molecules were calculated in the gas phase and in two different solvents, the study revealed that same tautomer is the most stable both in gas phase and in solution [9]. The usefulness of the quantum mechanical descriptors has been investigated by DFT, the relationship between molecular descriptors and biological activities have been produced [10]. The equilibrium geometries and harmonic frequencies of the 6-methylnicotinic acid have been investigated at density functional theory with satisfactory results [11]. Recently, we are investigated the sila- and thio- derivative of formohydroxamic acid in the same manner [12-13].
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Equilibrium, isotherms and thermodynamic studies of congo red adsorption onto Ceratophyllum Demersum

Equilibrium, isotherms and thermodynamic studies of congo red adsorption onto Ceratophyllum Demersum

The adsorption of Congo red onto Ceratophyllum demersum (C. demersum) has been investigated. It is observed from the experiments that an adsorbent prepared from the Ceratophyllum demersum plant is effective for the removal of Congo red from aqueous solutions at room temperature. The adsorption of Congo red is found to be dependent on contact time, initial dye concentration and adsorbent dose. The results indicate that Ceratophyllum demersum has a strong capability of removing Congo red dye directly from contaminated water. Therefore, it can be concluded that Ceratophyllum demersum could be used for the removal of pollutants from aqueous solutions. The equilibrium adsorption data is analyzed using three common adsorption models: Freundlich, Langmuir and Temkin. The thermodynamic parameters ∆G ° , ∆H ° , and ∆S ° are calculated for the adsorption of Congo red onto Ceratophyllum demersum. The Gibbs free energy change values show that the adsorption of Congo red onto Ceratophyllum demersum is spontaneous.
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Seed equilibrium moisture curves, water binding and its relationship with thermodynamic magnitudes

Seed equilibrium moisture curves, water binding and its relationship with thermodynamic magnitudes

Water molecules at low temperatures have lower kinetic energy, insufficient to overcome the corresponding adsorp- tion energy. They can also be linked with other organic mo- lecules like carbohydrates, protein and lipids at the atmos- phere-seed interface. This binding is based on hydrogen links that require exothermic reactions which decrease as T increases (Vega et al., 2006). This relationship between increased lipid content and fewer sorption sites is shown in Fig. 5. Temperature and seed fat content (SFC) caused a de- crease of the number and intensity of sorption sites with weak binding. Therefore, it is reasonable to believe that each species has a different number of sorption sites where weak binding is dominant, and that the intensity of these inter- actions also varies due to morphological characteristics. Fig. 2. Curves of equilibrium sorption isotherms for eight cultivars fitted by three hygroscopic models: D’Arcy-Watt (DAW) (long dashed line), Socorro (SOC) (small dashed line) and Henderson-Thompson (HTH) (solid line). Experimental values of equilibrium moisture content are represented with dots. A – cabbage, B – carrot, C – drybean, D – lettuce, E – maize, F – pepper, G – soybean, H – tomato.
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Perfect Equilibrium in a Bargaining Model

Perfect Equilibrium in a Bargaining Model

I will consider the following bargaining situation: two players have to reach an agreement on the partition of a pie of size 1.. After one party has made such an offer, the other[r]

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Breakdown of Local Thermodynamic Equilibrium...

Breakdown of Local Thermodynamic Equilibrium...

A great deal of effort has gone into approximating the actual case of many levels of excitation by setting up and solving the rate equations for three and four levels or approximating any particular transition of interest by an "equivalent two level atom" (see D.Mihalas 3 , pp. 391-394). However, the advent of modern, swift computers has made most of these approximations obsolete. Instead, one considers an n-level atom (with continuum) and solves the rate equations directly. We have already indicated that this procedure can be integrated into the standard algorithm for generating a model atmosphere quite easily. Consider the generalization of equations (15.2.22) through (15.2.24). Simply writing equations for each level, by balancing the transitions into the level with those out of the level, will yield a set of equations which are linear in the level populations. However, as we have already indicated, these equations are redundant by one. So far we have only needed population ratios for the source function, but if we are to find the population levels themselves, we will need an additional constraint. The most obvious constraint is that the total number of atoms and ions must add up to the abundance specified for the atmosphere. Mihalas 4 suggests using charge conservation, which is a logically equivalent constraint. Whatever additional constraint is chosen, it should be linear in the level populations so that the linear nature of the equations is not lost.
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Understanding Equilibrium in the IS/LM Model

Understanding Equilibrium in the IS/LM Model

The Equilibration Process: In struggling with the problem of teaching the student why the intersection of the IS and LM curves yields the general equilibrium solution to the interest rate and output variables, I wondered why students are able to understand quickly how a market equilibrates. The typical student knows that D=S generates the P e , Q e combination that we seek. He also knows, however, the process by which such a solution is reached. From the first course in economics he is taught that any price above the equilibrium price generates a surplus which forces suppliers to cut prices in order to sell their inventories. On the other hand, a P below P e results in a shortage and upward pressure on the price as consumers bid up the price. When asked why the intersection of S and D yields P e , the typical student responds with this story. The student hasn't memorized that S=D generates P e , he has learned that there is an "equilibration process" at work.
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The Determination of the Equilibrium Exchange Rates Based on a General Equilibrium Model

The Determination of the Equilibrium Exchange Rates Based on a General Equilibrium Model

It’s obvious that in the equilibrium of this economy the demand for each commodity will equal the supply of that commodity, and the unit expenditure of each agent will equal its unit revenue. In other words, there are no free commodity and no inactive firm in the equilibrium of this economy. Hence the equilibrium formulas can also be written as  T ( , )  T ( ) 

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Biosorption of Azure Dye with Sunflower Seed Hull: Estimation of Equilibrium, Thermodynamic and Kinetic Parameters

Biosorption of Azure Dye with Sunflower Seed Hull: Estimation of Equilibrium, Thermodynamic and Kinetic Parameters

The data obtained from biosorption experiments are generally represented by equilibrium isotherms. These provide more important parameters for designing and optimizing of the biosorption systems. Different isotherm models can be used to determine the biosorption characteristics of a biosorbent. In the present study the Azure dye biosorption was analyzed by three different models Langmuir, Freundlich and Dubinin– Radushkevich (D–R). The data were fitted and the calculated isotherm constants are presented in Table 1. The fundamental assumption of the Langmuir isotherm model is that biosorption takes place at specific sites within the biosorbent. Once a biosorbate occupies a binding site, no further biosorption occurs at this site. In the other words Langmuir model assumes that biosorbed layer is one molecule thickness (monolayer biosorption) [33] .
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Equilibrium Isotherm, Kinetic and Thermodynamic studies of Rhodamine B Adsorption using Thespesia populnea Bark

Equilibrium Isotherm, Kinetic and Thermodynamic studies of Rhodamine B Adsorption using Thespesia populnea Bark

There are essentially three steps in the adsorption process by porous adsorbents[14]. 1. solute transfer from the bulk solution to the external surface of the sorbent through liquid boundary layer(film resistance); 2. solute transfer from the sorbent surface the intraparticle actives sites(internal particle resistance); and 3. interaction of the solute with available sites on both the external and internal surface of the adsorbent (reaction resistance). One or more of the above mentioned steps may control the rate at which the solute is adsorbed on to the adsorbent. In this study, the kinetic of the dye removal were carried out to understand behavior of the chosen carbon. The adsorption of the Rhodamine B dye from an aqueous solution follows reversible first order kinetics, when a single species is considered on a heterogeneous surface. The heterogeneous equilibrium between the dye solution and the activated carbon have been expressed as
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Modelling thermally induced non-equilibrium gas flows by coupling kinetic and extended thermodynamic methods

Modelling thermally induced non-equilibrium gas flows by coupling kinetic and extended thermodynamic methods

In the present study, the application of coupling macro- and microscopic approaches for simulating thermally induced non-equilibrium flows has been explored. The R26 moment equation system is employed at the macroscopic level, meanwhile the Boltzmann model equation associated with the DVM are used to describe the gas dynamics at the microscopic level. Three types of thermally induced flows have been investigated with different Knudsen numbers and the results have been validated using DVM results. The simulation results show that the hybrid DVM/R26 approach can be faithfully used for thermally induced non-equilibrium low-speed flows. Since we only solve the Boltzmann model equation in the near-wall regions, tremendous computational memory and time can be saved in comparison with the DVM. The entropy fields also show that the reconstructed VDF f (5) is able to yield accurate results when the Knudsen number is less than unity. It is also interesting to find that, unlike the other flow parameters, the distributions of system entropy present totally different characteristics between the lower and higher Knudsen numbers in the temperature gradient cases. Author Contributions: Conceptualization, X.-J.G., D.R.E. and Y.Z.; software, W.Y. and X.-J.G.; validation, W.Y.; supervision, X.-J.G., D.R.E., Y.Z. and S.T.; original draft preparation, W.Y.
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