scholarly journals The calculation of specific heats for some important solid components in hydrogen production process based on CuCl cycle

2014 ◽  
Vol 18 (3) ◽  
pp. 823-831 ◽  
Author(s):  
Jurij Avsec
Keyword(s):  
Mathematical Model ◽  
Hydrogen Production ◽  
Thermodynamic Properties ◽  
Large Scale ◽  
Solid Phase ◽  
Statistical Thermodynamics ◽  
Thermochemical Cycle ◽  
Direct Production ◽  
Production Of Hydrogen ◽  
The Mathematical Model

Hydrogen is one of the most promising energy sources of the future enabling direct production of power and heat in fuel cells, hydrogen engines or furnaces with hydrogen burners. One of the last remainder problems in hydrogen technology is how to produce a sufficient amount of cheap hydrogen. One of the best options is large scale thermochemical production of hydrogen in combination with nuclear power plant. copper-chlorine (CuCl) cycle is the most promissible thermochemical cycle to produce cheap hydrogen.This paper focuses on a CuCl cycle, and the describes the models how to calculate thermodynamic properties. Unfortunately, for many components in CuCl cycle the thermochemical functions of state have never been measured. This is the reason that we have tried to calculate some very important thermophysical properties. This paper discusses the mathematical model for computing the thermodynamic properties for pure substances and their mixtures such as CuCl, HCl, Cu2OCl2 important in CuCl hydrogen production in their fluid and solid phase with an aid of statistical thermodynamics. For the solid phase, we have developed the mathematical model for the calculation of thermodynamic properties for polyatomic crystals. In this way, we have used Debye functions and Einstein function for acoustical modes and optical modes of vibrations to take into account vibration of atoms. The influence of intermolecular energy we have solved on the basis of Murnaghan equation of state and statistical thermodynamics.

Experimental Validation of the Mathematical Model of the Dimethyl Phthalate Degradation by Ozone in the Solid Phase

2020 ◽  
Vol 59 (37) ◽  
pp. 16136-16145
Author(s):  
Jaime Dueñas Moreno ◽  
Tatyana Poznyak ◽  
Julia Liliana Rodríguez ◽  
Isaac Chairez ◽  
Hector J. Dorantes-Rosales
Keyword(s):  
Mathematical Model ◽  
Experimental Validation ◽  
Solid Phase ◽  
Dimethyl Phthalate ◽  
The Mathematical Model

scholarly journals Approximation of potential-driven flow dynamics in large-scale self-similar tree networks

2011 ◽  
Vol 467 (2134) ◽  
pp. 2810-2824 ◽  
Author(s):  
Jason Mayes ◽  
Mihir Sen
Keyword(s):  
Mathematical Model ◽  
Analytical Solutions ◽  
Large Scale ◽  
Differential Algebraic Equations ◽  
Flow Dynamics ◽  
Algebraic Equations ◽  
Tree Networks ◽  
Self Similar ◽  
Large Scale Flow ◽  
The Mathematical Model

Dynamic analysis of large-scale flow networks is made difficult by the large system of differential-algebraic equations resulting from its modelling. To simplify analysis, the mathematical model must be sufficiently reduced in complexity. For self-similar tree networks, this reduction can be made using the network’s structure in way that can allow simple, analytical solutions. For very large, but finite, networks, analytical solutions are more difficult to obtain. In the infinite limit, however, analysis is sometimes greatly simplified. It is shown that approximating large finite networks as infinite not only simplifies the analysis, but also provides an excellent approximate solution.

Modeling of Macrosegregation and Secondary Phase Precipitation During Solidification of Binary Alloys

2002 ◽  
Author(s):  
O̸yvind Nielsen ◽  
Harald Laux ◽  
Anne Lise Dons
Keyword(s):  
Mathematical Model ◽  
Solid Phase ◽  
Binary Alloys ◽  
Secondary Phase ◽  
Cfd Model ◽  
Phase Precipitation ◽  
Solutal Convection ◽  
Metall Trans ◽  
Averaged Model ◽  
The Mathematical Model

A multiphase volume-averaged model describing macrosegregation in an alloy that solidifies by the formation and growth of a primary and a secondary solid phase has been formulated. The model is based on the work presented by Ni and Beckermann (Metall. Trans. 22B, 1991, p. 349), but is extended to account for secondary phase precipitation. A CFD model has been developed by implementation of the mathematical model in a commercial CFD code. Macrosegregation due to thermo-solutal convection in binary alloys with a stationary solid phase (primary and secondary solids) has been simulated. The predictions compare fairly well to experimental results and simulations previously reported in the literature.

The Numerical Simulation of Directional Solidification Process Temperature Field for Large-Scale Frustum of a Cone Ingot

2011 ◽  
Vol 189-193 ◽  
pp. 1476-1481
Author(s):  
Kun Liu ◽  
Zhe Wang ◽  
Ren Zhi Han ◽  
Zi Ping Ren
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Temperature Field ◽  
Directional Solidification ◽  
Large Scale ◽  
Solidification Process ◽  
Directional Solidification Process ◽  
Ingot Quality ◽  
Fluent Software ◽  
The Mathematical Model

By using Fluent software, the mathematical model of temperature field is established on directional solidification process for large-scale frustum of a cone ingot, and the result is analyzed by Origin software, Tecplot. The influences of different width/thickness ratio to directional solidification process of cone ingot are discussed in order to provide basis for design optimization and ingot quality improvement.

MODELING AND SIMULATION OF THE PRODUCTION OF HYDROGEN USING HYDROELECTRICITY IN VENEZUELA

2018 ◽  
pp. 88-95 ◽  
Author(s):  
A. Contrerasa ◽  
F. Possob ◽  
Т. N. Veziroglu
Keyword(s):  
Mathematical Model ◽  
Hydrogen Production ◽  
Modeling And Simulation ◽  
Regression Models ◽  
Low Cost ◽  
Total Cost ◽  
Time Horizons ◽  
Proposed Model ◽  
Production Of Hydrogen ◽  
The Cost

The purpose of this work is to develop and evaluate a mathematical model for the process of hydrogen production in Venezuela, via electrolysis and using hydroelectricity, with a view to using it as an energy vector in rural sectors of the country. Regression models were prepared to estimate the fluctuation of the main variables involved in the process: the production of hydrogen, the efficiency of energy conversion, the cost of hydroelectricity and the cost of the electrolyser. Finally, the proposed model was applied to various different time-horizons and populations, obtaining the cost of hydrogen production in each case. The results obtained are well below those mentioned in the references, owing largely to the low cost of the electricity used, which accounts for around 45% of the total cost of the system.

Nickel Multi-walled Carbon Nanotube Composite Electrode for Hydrogen Generation

2012 ◽  
Vol 1387 ◽  
Author(s):  
Nitin Kalra ◽  
Kalathur Santhanam ◽  
David Olney
Keyword(s):  
Carbon Nanotube ◽  
Hydrogen Production ◽  
Large Scale ◽  
Coulombic Efficiency ◽  
Superior Performance ◽  
Efficient Production ◽  
Scale Production ◽  
Production Of Hydrogen ◽  
Carbon Nanotube Composite ◽  
Decomposition Of Water

ABSTRACTThe electrochemical decomposition of water is an attractive method, however, the performance of the electrodes and efficiencies are of great concern in its large scale production. In this context, we wish to report here the superior performance of Ni-multiwalled carbon nanotube composite as cathode in the decomposition of water. The current voltage curves recorded with this electrode in different media showed a significant electrocatalysis in the reduction of hydrogen ion; the background electrolysis is shifted in the anodic direction. The nanocomposite composition has been found to be crucial in the efficient production of hydrogen. A coulombic efficiency of about 68% has been obtained at this electrode with a hydrogen production rate of 130L/m2 d. This electrode is more efficient than the 316L stainless steel (composition in percentage: C 0.019, Cr 17.3, Mo 2.04, Ni 11.3, Mn 1.04, N 0.041, Fe bulk) cathode that produces 10 ml/h at an area of 20 cm2 (5L/m2.h) (2). The results obtained with different electrolytes, performance variation with electrode composition, and current densities will be presented. The trials carried out using solar panel instead of DC power source showed similar hydrogen production rates and efficiencies.

scholarly journals Performance of rGO/TiO2 Photocatalytic Membranes for Hydrogen Production

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 218 ◽  
Author(s):  
Juan Corredor ◽  
Eduardo Perez-Peña ◽  
Maria J. Rivero ◽  
Inmaculada Ortiz
Keyword(s):  
Hydrogen Production ◽  
High Performance ◽  
Large Scale ◽  
Membrane Surface ◽  
Life Time ◽  
Dip Coating ◽  
Production Of Hydrogen ◽  
Nafion Membranes ◽  
The Matrix ◽  
Low Efficiency

Although there are promising environmental and energy characteristics for the photocatalytic production of hydrogen, two main drawbacks must be overcome before the large- scale deployment of the technology becomes a reality, (i) the low efficiency reported by state of the art photocatalysts and, (ii) the short life time and difficult recovery of the photocatalyst, issues that need research and development for new high performance catalysts. In this work 2% rGO/TiO2 composite photocatalysts were supported over Nafion membranes and the performance of the photocatalytic membrane was tested for hydrogen production from a 20% vol. methanol solution. Immobilization of the composite on Nafion membranes followed three different simple methods which preserve the photocatalyst structure: solvent-casting (SC), spraying (SP), and dip-coating (DP). The photocatalyst was included in the matrix membrane using the SC method, while it was located on the membrane surface in the SP and DP membranes showing less mass transfer limitations. The performance of the synthesized photocatalytic membranes for hydrogen production under UVA light irradiation was compared. Leaching of the catalytic membranes was tested by measuring the turbidity of the solution. With respect to catalyst leaching, both the SC and SP membranes provided very good results, the leaching being lower with the SC membrane. The best results in terms of initial hydrogen production rate (HPR) were obtained with the SP and DP membrane. The SP was selected as the most suitable method for photocatalytic hydrogen production due to the high HPR and the negligible photocatalyst leaching. Moreover, the stability of this membrane was studied for longer operation times. This work helps to improve the knowledge on the application of photocatalytic membranes for hydrogen production and contributes in facilitating the large-scale application of this process.

scholarly journals Investigation of Thermodynamic Properties of the Slurry of the Molding Process Beryllium Ceramics

Proceedings ◽  
2018 ◽  
Vol 2 (22) ◽  
pp. 1391
Author(s):  
Zamira Sattinova ◽  
Gaukhar Ramazanova ◽  
Bakhytzan Assilbekov ◽  
Elmira Mussenova
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Thermal Properties ◽  
Heat Exchange ◽  
Thermodynamic Properties ◽  
Physical Properties ◽  
Beryllium Oxide ◽  
Molding Process ◽  
The Mathematical Model

Obtaining of ceramic fabrications by hot molding from dispersion materials with anomalous physical properties, such as BeO is particularly complicated. In this case, the difficulties of obtaining of quality products were caused firstly by thermal properties of beryllium oxide, in particular, its unique thermal conductivity. Results of experiments and calculations of the mathematical model of the motion and heat exchange of the slurry mass in the annular cavity are presented. The results of experiments and calculations show the process of molding of the slurry in the annular cavity.

scholarly journals Mathematical simulation of catalytic paste flow in a ram extruder

2004 ◽  
Vol 58 (9) ◽  
pp. 387-392
Author(s):  
A.V. Zhensa ◽  
V.V. Kostutchenko ◽  
I.A. Petropavlovskiy ◽  
V.A. Filippin ◽  
E.M. Koltsova
Keyword(s):  
Mathematical Model ◽  
Film Thickness ◽  
Volume Content ◽  
Solid Phase ◽  
Functional Dependencies ◽  
Plastic Strength ◽  
Dispersed Phases ◽  
The Mathematical Model

A mathematical model was developed for the stage of catalyst paste preparation. The mathematical model allows the calculation of solvate film thickness and volume content of the solid phase at any moment of time. Functional dependencies were found, which correlated the solvate film thickness and volume content of the solid phase with the plastic strength and viscosity of catalyst pastes. A range of plastic strength was determined, which ensures the optimum forming properties of the pastes. The mathematical model allowed the determination of the concentrations of the components of the continuous and dispersed phases, which ensured the optimum paste forming rheological properties, which, in turn, influence the end properties of an a-FezOs catalyst. The significant role of the solvate film thickness in the forming properties of pastes was demonstrated.

scholarly journals Numerical model of heat transfer in three phases of the poroelastic medium

2016 ◽  
Vol 38 (2) ◽  
pp. 53-59
Author(s):  
Anna Uciechowska-Grakowicz ◽  
Tomasz Strzelecki
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Solid Phase ◽  
Irreversible Thermodynamics ◽  
Pore Fluid ◽  
Gas Filtration ◽  
Two Phase ◽  
Phase Medium ◽  
Thermal Consolidation ◽  
The Mathematical Model

Abstract In this paper, the results of numerical analysis of the thermal consolidation of a two phase medium, under the assumption of independent heat transfer in fluid and the solid phase of the medium, are presented. Three cases of pore fluid were considered: liquid, represented by water, and gas, represented by air and carbon dioxide. The mathematical model was derived from irreversible thermodynamics, with the assumption of a constant heat transfer between the phases. In the case of the accepted geometry of the classical dimensions of the soil sample and boundary conditions, the process leads to equalization of temperatures of the skeleton on the pore fluid. Heat transfer is associated with the fluid flow in the pores of the medium. In the case of gas as the pore fluid, a non-linear mathematical model of gas filtration through the pores of the medium was accepted. For the computing process, relationships between viscosity or density and temperature proposed by other authors were taken into account. Despite accepting mechanical constants of the solid phase that do not depend on temperature, the obtained model is nonlinear and develops the classical Biot–Darcy model.

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