Experimental Study on the Flow Patterns and Two-phase Pressure Drops in a Horizontal Impacting T- Junction

The present paper analyzes the experimental results concerning the flow patterns and pressure drops in two-phase flow through an horizontal impacting T-junction, whose outlet pipes are aligned and perpendicular to the inlet pipe. The test section consists of plexiglass pipes with inner diameter of 10 mm. A mixture of water and air at ambient temperature and pressures up to 2.4 bar flows through the T-junction, with different splitting of flow rates in the two outlet branches; superficial velocities of air and water in the inlet pipe are varied up to a maximum of 35 m/s and 3.5 m/s respectively. The flow patterns occurring in the inlet and branch pipes were compared with the predictions of Baker’s and Taitel – Dukler’s maps. The pressure drops along the branches have been measured relatively to different splitting of the flow rate through the two branches and the pressure loss coefficients in the junction have been evaluated. Friction pressure drops have allowed us to evaluate two-phase friction multipliers, which have then been compared to the predictions of Lockhart-Martinelli, and Friedel correlations. Local pressure drops were extrapolated at the junction centre and analyzed; the two-phase multiplier has been evaluated and compared with the predictions of Chisholm correlation; the value of the empirical coefficient that minimizes the discrepancies has also been evaluated

Thermal hydraulic analysis of Alfred bayonet tube steam generator

The paper analyzes the performance of ALFRED steam generator from the thermal-hydraulic point of view highlighting the effect of some design features. The parameters object of the study are the regenerative heat transfer, the dimension of the inner tube and the length of the bayonet. The system code RELAP5-3D/2.4.2 has been chosen for the analysis. Sensitivities analysis allowed the determination of the different design parameters influence, here briefly summarized. The increase of regenerative heat transfer affects the efficiency of the steam generator through a degradation of the outlet steam quality: the number of bayonet tubes required to remove the nominal power increases with the increase of the global heat transfer coefficient of the inner tube. A higher inner diameter results in a larger surface area for the regenerative heat transfer and in a higher heat transfer coefficient in the annular region because of the reduction of the cross section. The result is an improvement of the performances of the steam generator thanks to the dimension reduction of the annular gap. Finally, if the height of the bayonet tube is reduced by 1 meter, the number of bayonet tubes required to remove the nominal power increases up to 20%

One-step synthesis of a highly homogeneous SBA-NHC hybrid material: En route to single-site NHC-metal heterogeneous catalysts with high loadings

The one-step synthesis of a mesoporous silica of SBA type, functionalized with a 1-(2,6-diisopropylphenyl)-3-propyl-imidazolium (iPr2Ar-NHC-propyl) cation located in the pore channels, is described. This material was obtained by the direct hydrolysis and co-condensation of tetraethylorthosilicate (TEOS) and 1-(2,6-diisopropylphenyl)-3-[3-(triethoxysilyl)propyl]-imidazolium iodide in the presence of Pluronic P123 as a non-ionic structure-directing agent and aqueous HCl (37%) as an acid catalyst. Small-angle X-ray diffraction measurements, scanning and transmission electron microscopies, as well as dinitrogen sorption analyses revealed that the synthesized material is highly mesoporous with a 2D hexagonal arrangement of the porous network. 13C and 29Si CP-MAS NMR spectroscopy confirmed that the material contains intact iPr2Ar-NHC-propyl cations, which are covalently anchored via silicon atoms fused into the silica matrix. Moreover, comparison of the latter data with those of an analogous post-synthetic grafted SBA–NHC material allowed us to establish that, as expected, (i) it is most probably more homogeneous and (ii) it shows a more robust anchoring of the organic units. Finally, elemental mapping by energy dispersive X-ray spectroscopy in the scanning electron microscope demonstrated a very homogeneous distribution of the imidazolium units within the one-pot material, moreover with a high content. This study thus demonstrates that a relatively bulky and hydrophilic imidazolium unit can be directly co-condensed with TEOS in the presence of a structure-directing agent to provide in a single step a highly ordered and homogeneous mesoporous hybrid SBA–NHC material, possessing a significant number of cationic NHC sites

Two-phase flow in a horizontal t-junction : pressure drop and phase separation

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.An experimental investigation of dividing flow rates and pressure drops in a plexiglas tee junction with horizontal inlet, run, and branch sides using air-water mixtures has been performed. The branch stream is orthogonal to the inlet and run streams. The pipes forming the tee junction are about 1 m long, their inner diameter is 10 mm. The flow loop was supplied with compressed air and water through a mixing tee, at 1.5 bar and approximately ambient temperature. Air flow rate ranges from 0.3 to 9 Nl/s, water flow rate from 14.5 to 58 g/s, air superficial velocity from 1.5 to 47 m/s, water superficial velocity from 0.2 to 0.7 m/s and flow quality from 0.6% to 43%. The extraction ratio (branch flow rate / inlet flow rate) ranges from 0 to 1. Intermittent (bubble and slug flow) and annular flow patterns, as well as transition flow patterns have been obtained. Experimental values of flow rate, phases superficial velocity, extraction ratio and pressure drops across the tee junction pipes are here reported. Pressure drop test results across the inlet and branch pipes have also been compared with predicted ones. A new pressure drop correlation have been derived from test data.cs201

Two-phase flow in a horizontal t-junction : pressure drop and phase separation

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.An experimental investigation of dividing flow rates and pressure drops in a plexiglas tee junction with horizontal inlet, run, and branch sides using air-water mixtures has been performed. The branch stream is orthogonal to the inlet and run streams. The pipes forming the tee junction are about 1 m long, their inner diameter is 10 mm. The flow loop was supplied with compressed air and water through a mixing tee, at 1.5 bar and approximately ambient temperature. Air flow rate ranges from 0.3 to 9 Nl/s, water flow rate from 14.5 to 58 g/s, air superficial velocity from 1.5 to 47 m/s, water superficial velocity from 0.2 to 0.7 m/s and flow quality from 0.6% to 43%. The extraction ratio (branch flow rate / inlet flow rate) ranges from 0 to 1. Intermittent (bubble and slug flow) and annular flow patterns, as well as transition flow patterns have been obtained. Experimental values of flow rate, phases superficial velocity, extraction ratio and pressure drops across the tee junction pipes are here reported. Pressure drop test results across the inlet and branch pipes have also been compared with predicted ones. A new pressure drop correlation have been derived from test data.cs201

A Novel Approach for an Integrated Straw tube-Microstrip Detector

We report on a novel concept of silicon microstrips and straw tubes detector, where integration is accomplished by a straw module with straws not subjected to mechanical tension in a Rohacell $^{\circledR}$ lattice and carbon fiber reinforced plastic shell. Results on mechanical and test beam performances are reported on as well.Comment: Accepted by Transactions on Nuclear Science (2005). 11 pages, 9 figures, uses lnfprep.st

Surgical ‘damage control’ treatment of a large retroperitoneal liposarcoma encasing a horseshoe kidney

Damage control is a surgical strategy for severely compromised trauma patients based on speed control of life-threatening injuries that aims to rapidly resuscitate patients in an intensive care unit (ICU). We report on the use of such therapeutic strategy in a patient affected by a retroperitoneal sarcoma concomitant to a horseshoe kidney, a relatively rare anatomical malformation

Multifunctional Epoxy/Nanocomposites Based on Natural Moroccan Clays with High Antimicrobial Activity: Morphological, Thermal and Mechanical Properties

In this study, a series of new epoxy/clay nanocomposites (ECN) has been prepared and characterized in order to investigate the properties and compare the effect of the unmodified Moroccan clay on the structure and properties of the composite materials. Five natural clays have been used to reinforce the neat epoxy resin with 1% wt and 5% wt achieving the clay dispersion only through strong milling and mechanical stirring without previous organic modifications of the clays. The quality of clay dispersion in the epoxy matrix and the morphology of nanocomposites have been studied by transmission electron microscopy (TEM), environmental scanning electron microscopy (ESEM), and X-ray diffraction (XRD). The mechanical and thermal properties have also been investigated. The antimicrobial activity of the nanocomposites has been tested against E. coli and S. aureus in order to evaluate their applicability as advanced antimicrobial materials. The results showed that the epoxy/crude clay nanocomposites exhibited a high inhibition action attending 99% against both bacteria in the case of the clay labeled A5

Multifunctional Epoxy/Nanocomposites Based on Natural Moroccan Clays with High Antimicrobial Activity: Morphological, Thermal and Mechanical Properties

In this study, a series of new epoxy/clay nanocomposites (ECN) has been prepared and characterized in order to investigate the properties and compare the effect of the unmodified Moroccan clay on the structure and properties of the composite materials. Five natural clays have been used to reinforce the neat epoxy resin with 1% wt and 5% wt achieving the clay dispersion only through strong milling and mechanical stirring without previous organic modifications of the clays. The quality of clay dispersion in the epoxy matrix and the morphology of nanocomposites have been studied by transmission electron microscopy (TEM), environmental scanning electron microscopy (ESEM), and X-ray diffraction (XRD). The mechanical and thermal properties have also been investigated. The antimicrobial activity of the nanocomposites has been tested against E. coli and S. aureus in order to evaluate their applicability as advanced antimicrobial materials. The results showed that the epoxy/crude clay nanocomposites exhibited a high inhibition action attending 99% against both bacteria in the case of the clay labeled A5