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Common Interface (common + interface)
Selected AbstractsNew insight into suction and dilution effects in CE coupled to MS via an ESI interface.ELECTROPHORESIS, Issue 10 2009Dilution effect Abstract The hyphenation of CE with MS is nowadays accepted as a powerful analytical approach. As far as ESI, the most common interface, is concerned, one challenge is to provide the most sensitive as well as quantitative information, which is quite a difficult task, as it is linked, among other factors, to suction and dilution effects. In the coaxial ESI configuration, it has been previously demonstrated that suction effect depends on many parameters inherent to the ESI interface geometry, the prevailing ones being the CE capillary protrusion from the interface needle, the sheath liquid (SL) and the overall BGE flow rates and velocity profile. In this paper, dilution effect is studied, as the CE electrolyte is mixed with SL at the interface. Considering peak intensity and efficiency, this effect was studied as a function of the various parameters of the interface (capillary protrusion from the SL tube, nebulizing gas, SL and CE electrolyte flow rates) or of the source (skimmer and ESI voltages, drying gas flow rate and temperature). It appears that the dilution effect seems slightly lower than what can be anticipated from the proportions of the liquid flow rates. This study also indicates that suction effect has to be considered first to better understand the dilution phenomenon, as suction effect leads to an increase in peak intensity, before a dilution effect appears. [source] A numerical approximation of the thermal coupling of fluids and solidsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2009Javier Principe Abstract In this article we analyze the problem of the thermal coupling of fluids and solids through a common interface. We state the global thermal problem in the whole domain, including the fluid part and the solid part. This global thermal problem presents discontinuous physical properties that depend on the solution of auxiliary problems on each part of the domain (a fluid flow problem and a solid state problem). We present a domain decomposition strategy to iteratively solve problems posed in both subdomains and discuss some implementation aspects of the algorithm. This domain decomposition framework is also used to revisit the use of wall function approaches used in this context. Copyright © 2008 John Wiley & Sons, Ltd. [source] Homogenization of a composite medium with a thermal barrierMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 4 2004Mongi Mabrouk Abstract In this work, we consider a heat transfer problem between two periodic connected media exchanging a heat flux throughout their common interface. The interfacial exchange coefficient , is assumed to tend to zero or to infinity following a rate ,=,(,) when the size ,of the basic cell tends to zero. Three homogenized problems are determined according to the value of ,=lim,,0,/,. Copyright © 2004 John Wiley & Sons, Ltd. [source] CFD modeling of rotary cement kilnsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2008Kaustubh S. Mujumdar Abstract Rotary cement kilns are widely used to convert calcineous raw meal into cement clinker, and are key components in the cement industry. In this article, we report a comprehensive computational fluid dynamics (CFD)-based model to capture key transport processes in rotary cement kilns. Separate but coupled computational models were developed for the bed and the freeboard regions of the rotary kiln. The complex swirling airflow produced by kiln burners, coal combustion, gas-phase combustion of volatile matter and radiative heat transfer in the freeboard region were modeled. The clinkerization reactions in the bed region were modeled assuming solids as pseudo fluids. Coating formation in cement kilns (for both bed and freeboard regions) was considered. Appropriate source and sink terms were developed to model transfer of CO2 from the bed to the freeboard region due to calcination reaction in the bed region. The developed bed and freeboard models were coupled by mass and energy communication through common interface. These coupled computational models were able to quite satisfactorily predict the available data from industrial kilns and previously published results. The computational models were also able to capture the intricacies of the burning zones of rotary cement kilns for changing burner-operational parameters like axial to swirl ratio and oxygen enrichment. The developed approach, computational models and simulation results will not only help in developing better understanding of cement kilns but also provide quantitative information about influence of burner design and other design parameters on kiln performance. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Identification of desulphoglucosinolates in Brassicaceae by LC/MS/MS: Comparison of ESI and atmospheric pressure chemical ionisation-MSMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 12 2007Nadine S. Zimmermann Abstract In order to develop a sensitive method for the detection of desulphoglucosinolates by HPLC-MS, the two most common interfaces for HPLC-MS, atmospheric pressure chemical ionisation (APCI) and ESI, were compared. While working with the APCI-interface the evaporation temperature and corona amperage were optimised. In doing so 300°C and 6 ,A proved to be most suitable for aliphatic and indole desulphoglucosinolates. The use of formic acid instead of water in the eluent in HPLC-ESI-MS measurements increased the sensitivity for the indole desulphoglucosinolates in the presence of 1 mM formic acid, while the sensitivity for the aliphatic desulphoglucosinolate desulphoglucoraphanin was substantially increased by the presence of 5 mM formic acid. Using an Agilent ion trap, two optimisation procedures for the MS parameters, smart and expert mode, were available. In smart mode the software optimises several parameters automatically, which is much more time efficient than expert mode, in which the optimisation is done manually. It turned out that ESI-MS is most sensitive in smart mode, while for APCI-MS a higher sensitivity could be gained using the expert mode. Comparing both interfaces, APCI-MS was more sensitive than ESI-MS. However, no additional information, in terms of structure determination, was obtained by APCI-MS. [source] | ||||||||||