Search results for "isotherm"
showing 10 items of 268 documents
Development of a combined solver to model transport and chemical reactions in catalytic wall-flow filters
2017
Abstract In this work, we develop a non-isothermal model for diesel particulate filters including exothermic and competing chemical reactions. We begin with an isothermal, single-reaction model and we gradually increase its complexity. By comparing various models, we aim at establishing the minimum degree of complexity required to effectively model the system under investigation. Based on the numerical simulations, we conclude that isothermal models are adequate only if the temperature of the catalyst is, at all times, completely below or completely above a critical temperature. However, if the goal is to predict the critical temperature, only non-isothermal models should be used. The resul…
Determination of Kinetic and Thermochemical Parameters of a Substitution Reaction at a Square-Planar Palladium(II) Complex in Water/AOT/n-Heptane Mic…
1995
Abstract The substitution reaction [Pd(bipy)(en)] 2+ + en → [Pd(en) 2 ] 2+ + bipy (where bipy = 2,2′-bipyridine and en = ethylenediamine) has been studied in water and water/AOT/ n -heptane microemulsions at various values of the molar ratio R ( R = [water]/[AOT]) by flow microcalorimetry. From calorimetric data, molar enthalpies of reaction and rate constants were obtained. These quantities indicate that, by increasing R , the reaction becomes less exothermic and its rate constant decreases, trending to the value observed in water. These features can be reasonably rationalized in terms of the peculiar solvation state of reactants inside the AOT reversed micelles and/or the peculiar physico…
Sugar reduction in extruded cereal based products : impact of water content on the structure and molecular dynamics in such material
2019
Low-moisture biopolymer-based systems are commonly encountered in food. Obviously, understanding the physical basis of their quality: e.g texture, or performance over time or as a function of their composition is of primary importance. The objectives of this work were to evaluate how the presence of sucrose and water content affects physico-chemical properties. The physical stability of these materials were monitored through an insight at different molecular scales. Then the relations between the multi-scale studies were investigated. The effect of sucrose (0–20%) and feed water (10 and 15%) on extrusion blends was studied using a twin screw extruder under the same processing settings. The …
(Photo)catalyst characterization techniques: Adsorption isotherms and BET, SEM, FTIR, UV-Vis, photoluminescence, and electrochemical characterizations
2019
This chapter reports on some characterization techniques that are commonly used for catalysts and photocatalysts. Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), UV-visible (UV-Vis), photoluminescence (PL), and electrochemical characterization techniques are presented with experimental details and actual case studies from literature are discussed. The chapter starts with adsorption phenomena on (photo)catalysis and adsorption isotherms are presented. Then BET analysis technique and its applications in (photo)catalysis are explained. Morphological properties (SEM), functional groups, and the interaction of substrate (and inter…
Calorimetric investigation of the vulcanization of factice
1991
Sulphur factice is produced from a mixture of a vegetable oil and sulphur at temperatures between 130 and 160‡C. The slow exothermal vulcanization results in rubber-like elastomers. We have developed an isothermal calorimeter for measurements both in the liquid and the solid state and simulated the production process at the laboratory scale. The compensating calorimeter consists of a hot plate equipped with thin aluminium rods descending into a Dewar vessel. Besides optimization of the temperature control, remarkable savings of time were achieved by previous elaidinization of the oil using hydrosulphide.
Thermoosmotic transfer of sterically stabilized ferrofluid particles in non-isothermal capillary porous layer
2005
Experiments on thermodiffusive transfer of ferrofluid nanoparticles in capillary porous layer are presented. The layer consists of a number of capillary filter sheets pressed between two plates of different temperatures. Steady profiles of particle concentration are detected after the experiment from magnetization of each filter sheet. It is shown that particle separation in porous layer is remarkably influenced by thermoosmotic forces. The observed effect is different for colloids of various surfactants and of various carrier liquids.
Non-isothermal mass transfer of ferrocolloids through porous membrane
2011
Abstract The present paper deals with transport properties of ferrofluid nanoparticles in non-isothermal capillary-porous layer. Experiment establishes that the temperature difference, which is applied across the layer, induces a thermoosmotic pressure gradient directed toward increasing temperature. The measurement results are interpreted in a frame of phenomenology of linear irreversible thermodynamics. The transport coefficients are evaluated comparing the measured separation curves with approximate solution of the corresponding mass transfer problem.
Natural convection heat transfer in a partially—or completely—partitioned vertical rectangular enclosure
1991
Abstract The effect of symmetric partitions protruding centrally from the end walls of a rectangular vertical enclosure on heat transfer rates is investigated numerically. The enclosure has opposite isothermal walls at different temperatures. The Rayleigh number is varied from 10 4 to 10 7 and the aspect ratio from 0.5 to 10. The thickness of the partitions is fixed and equal to one tenth of the width of the enclosure. Their non-dimensional length ( L / H ) is varied from 0 (non-partitioned enclosure) to 0.5 (two separate enclosures). The effect of different thermal boundary conditions at the end walls and at the partitions is included in the investigation.
Numerical evidence for a thermal driving force during adsorption of butane in silicalite.
2009
International audience; The transport properties of nano-porous materials determine their applicability, e.g. as separators or catalysts (J. Ka¨rger, D. Ruthven. Diffusion in zeolites, Wiley, New York (1991); L.V.C. Rees, D. Shen. Adsorption of gases in zeolite molecular sieves. In Introduction to Zeolite Science and Practice, Studies in surface science and catalysis, H.V.C. van Bekkum, E.M. Flanigen, P.A. Jacobs, J.C. Jansen (Eds.), vol. 137, pp. 579–631, Elsevier, Amsterdam (2001)). Adsorption in zeolites is explained as a two-step process; adsorption to the external crystal surface and subsequent intra-crystalline diffusion (R. M. Barrer. Porous crystal membranes. J. Chem. Soc. Faraday T…
High-Performance PCR for Alleles Discrimination of Chromo-Helicase-DNA Binding Protein (CHD1) Gene in Bird Sexing
2023
Genetic analyses aiming at assessing the presence of specific sequences or alleles are often carried out by PCR. Sexing of most birds is nowadays based on PCR with “universal” primers and relies on the assessment of the presence of the sex-linked CHD1-Z and -W alleles. The entire workflow is relatively time-consuming, especially for batch analyses, whereas methods that allow carrying out the entire procedure in a short time are highly desirable. The only method for outdoor analyses reported so far relies on LAMP; however; it fails to work properly in Procellariiformes. Besides improving the LAMP test; we have developed a PCR-based DNA amplification procedure (named high-performance PCR); wh…