Search results for "Flow Rate"
showing 10 items of 166 documents
Prediction models to analyse the performance of a commercial-scale membrane distillation unit for desalting brines from RO plants
2018
Abstract Desalting brines from Reverse Osmosis (RO) plants is one of the most promising applications of Membrane Distillation (MD) systems. The development of accurate models to predict MD system performances plays a significant role in the design of this kind of industrial applications. In this paper, a commercial-scale Permeate-Gap Membrane Distillation (PGMD) module was modelled by means of two different approaches: Response Surface Methodology (RSM) and Artificial Neural Networks (ANN). Condenser inlet temperature, evaporator inlet temperature, feed flow rate and feed water salt concentration were selected as inputs of the model, while permeate flux and Specific Thermal Energy Consumpti…
Nitrogen recovery using a membrane contactor: Modelling nitrogen and pH evolution
2020
[EN] A hollow fibre membrane contactor has been applied for nitrogen recovery from anaerobic digestion supernatant at different operating conditions obtaining nitrogen recovery efficiencies over 99 %. A mathematical model able to represent the time evolution of pH and nitrogen concentration during the recovery process is presented in this paper. The developed model accurately reproduced the results obtained in 26 experiments carried out at different pH values (from 9 to 11), temperatures (from 25 to 35 degrees C), membrane surfaces (from 1.2 to 2.4 m(2)) and feed flow rates (from 0.33 x 10(-5) to 5.83 x 10(-5) m(3)/s) predicting the variations in nitrogen recovery rates measured at the diff…
Observable Quantities for Electrodiffusion Processes in Membranes
2008
Electrically driven ion transport processes in a membrane system are analyzed in terms of observable quantities, such as the apparent volume flow, the time dependence of the electrolyte concentration in one cell compartment, and the electrical potential difference between the electrodes. The relations between the fluxes and these observable quantities are rigorously deduced from balances for constituent mass and solution volume. These relations improve the results for the transport coefficients up to 25% with respect to those obtained using simplified expressions common in the literature. Given the practical importance of ionic transport numbers and the solvent transference number in the ph…
Origin and correction of the deviations in retention times at increasing flow rate with Chromolith columns.
2010
Chromoliths can be used at flow rates beyond those feasible for conventional microparticulate packed columns. Ideally, the plots of the retention time versus the inverse of delivered flow rate should exhibit y-intercept of zero. However, significant positive deviations correlating with the solute polarity were observed for several compounds chromatographed with a Chromolith column, owing to the increased system pressure. Consequently, the dead time marker exhibits a smaller deviation, making the retention factors depend on the flow rate. Chromoliths are made of a silica-based monolith encapsulated within a PEEK tube, and should suffer larger stress with pressure than stainless steel columns…
Economic analysis of the scale-up and implantation of a hollow fibre membrane contactor plant for nitrogen recovery in a full-scale wastewater treatm…
2021
[EN] Nitrogen recovery technologies such as the hollow fibre membrane contactor are now being developed. However, an economic analysis is needed prior to their full-scale application in wastewater treatment plants. The aim of this study was to analyse the economic and environmental aspects of scaling-up this method. To achieve it, a full-scale 40,000 m3·day¿1-wastewater treatment plant influent flow rate was simulated jointly with a membrane contactor plant to evaluate the minimum costs of optimum operating conditions of membrane contactors (pH, feed flow rate and membrane surface). The optimum conditions for treating 600 m3·day¿1 of reject water was found to be 10 pH, 0.08 m3·s¿1 feed flow…
DNP in MRI: an in-bore approach at 1.5 T.
2011
Abstract We have used liquid state (“Overhauser”) Dynamic Nuclear Polarization (DNP) to significantly enhance the signal to noise ratio (SNR) of Magnetic Resonance Imaging (MRI). For the first time this was achieved by hyperpolarizing directly in the MRI-scanner field of 1.5 T in continuous flow mode and immediately delivering the hyperpolarized substance to the imaging site to ensure maximum contrast between hyperpolarized sample and sample at thermal polarization. We achieve a maximum absolute signal enhancement factor of 98; while the hyperpolarized sample is transported at a flow rate of up to 30 ml/h yielding an average flow speed up to 470 mm/s over a distance of approximately 80 mm. …
A semi-empirical approach for predicting two-phase flow discharge through branches of various orientations connected to a horizontal main pipe
2010
Abstract The subdivision of two-phase flow in branching conduits consisting of a large horizontal main pipe with upward, downward, or lateral branches of reduced diameter is of great interest in various technological fields. For example, these conduits are important in light-water nuclear reactors (LWRs) in the case of a small break loss-of-coolant accident (SBLOCA) in a leg of the reactor's primary coolant loops, as well as for breaks or valve malfunctions in a large pipeline. In these kinds of circumstances, the relevant phenomenology often involves phase stratification coupled with possible liquid entrainment or gas pool-through phenomena. Therefore, these phenomena were studied in depth…
On the numerical assessment of the thermal-hydraulic operating map of the DEMO Divertor Plasma Facing Components cooling circuit
2020
Abstract Within the framework of the Work Package DIV 1 - “Divertor Cassette Design and Integration” of the EUROfusion action, a research campaign has been jointly carried out by University of Palermo and ENEA to investigate the thermal-hydraulic behaviour of the DEMO divertor cassette cooling system, focussing the attention on the 2018 configuration of the Plasma Facing Components (PFCs) circuit consistent with the DEMO baseline 2017. The research campaign has been carried out following a theoretical-computational approach based on the finite volume method and adopting the commercial Computational Fluid-Dynamic (CFD) code ANSYS CFX. A steady-state CFD analysis has been carried out for the …
Storm sewer pressurization transient – an experimental investigation
2014
Pipe pressurization is examined experimentally by 144 laboratory experiments in a circular tilting pipe between two tanks, in which the transient was triggered by sudden closing of the downstream tank outlet. The experiments cover ranges of values of slope, velocity and filling ratio of the open-channel flow not explored in previous studies. Situations involving considerable air quantity and consequent intense pressure oscillations were also reproduced. Two different pressurization patterns, defined as “smooth” and “abrupt”, were observed, but only the abrupt pattern produced intense pressure oscillations. The comparison among all the abrupt pressurization surges showed how the oscillations…
PDMS membranes for feasible recovery of dissolved methane from AnMBR effluents
2020
[EN] This study aimed to evaluate the feasibility of degassing membrane (DM) technology for recovering dissolved methane from AnMBR effluents. For that purpose, a PDMS membrane module was operated for treating the effluent from an AnMBR prototype-plant, which treated urban wastewater (UWW) at ambient temperature. Different transmembrane pressures and liquid flow rates were applied for evaluating methane recovery efficiency. Maximum methane recoveries were achieved when increasing the vacuum pressure and reducing the liquid flow rate, reaching a maximum methane recovery efficiency of around 80% at a transmembrane pressure (TMP) of 0.8 bars and a treatment flow rate (Q(L)) of 50 L h(-1). The …