The Effect of Inclination Angle and Reynolds Number on the Performance of a Direct Contact Membrane Distillation (DCMD) Process

In this numerical study, a direct contact membrane distillation (DCMD) system has been modeled considering various angles for the membrane unit and the Reynolds number range of 500 to 2000. A two-dimensional model developed based on the Navier–Stokes, energy, and species transport equations were used. The governing equations were solved using the finite volume method (FVM). The results showed that with an increase in the Reynolds number of up to 1500, the heat transfer coefficient for all membrane angles increases, except for the inclination angle of 60°. Also, an increase in the membrane angle up to 90° causes the exit influence to diminish and the heat transfer to be augmented. Such findings revealed that the membrane inclination angle of 90° (referred to as the vertical membrane) with Reynolds number 2000 could potentially have the lowest temperature difference. Likewise, within the Reynolds numbers of 1000 and 2000, by changing the inclination angle of the membrane, temperature difference remains constant, however, for Reynolds numbers up to 500, the temperature difference reduces intensively

Performance Investigation of O-Ring Vacuum Membrane Distillation Module for Water Desalination

A new O-ring flat sheet membrane module design was used to investigate the performance of Vacuum Membrane Distillation (VMD) for water desalination using two commercial polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) flat sheet hydrophobic membranes. The design of the membrane module proved its applicability for achieving a high heat transfer coefficient of the order of 103 (W/m2 K) and a high Reynolds number (Re). VMD experiments were conducted to measure the heat and mass transfer coefficients within the membrane module. The effects of the process parameters, such as the feed temperature, feed flow rate, vacuum degree, and feed concentration, on the permeate flux have been investigated. The feed temperature, feed flow rate, and vacuum degree play an important role in enhancing the performance of the VMD process; therefore, optimizing all of these parameters is the best way to achieve a high permeate flux. The PTFE membrane showed better performance than the PVDF membrane in VMD desalination. The obtained water flux is relatively high compared to that reported in the literature, reaching 43.8 and 52.6 (kg/m2 h) for PVDF and PTFE, respectively. The salt rejection of NaCl was higher than 99% for both membranes

Recent developments in forward osmosis membranes using carbon-based nanomaterials

Contamination and industrial development are among the reasons for water quality deterioration beyond treatability by conventional processes. Unfortunately, conventional water and wastewater treatment technologies are not always capable of handling industrial wastewaters, and hence more advanced treatment technologies are required. The new trend of osmotically driven membrane technologies has demonstrated an exceptional efficiency for water purification and treatment including seawater desalination. Compared to pressure-driven membrane processes, forward osmosis (FO) technology, as a standalone process, is more energy-efficient, and less prone to membrane fouling than its predecessor reverse osmosis (RO) technology. However, forward osmosis suffers a severe concentration polarization that is acting on both sides of the membrane and results in a sharp decline in water flux. A thinner support layer has been recommended to lessen the concentration polarization impact in the FO process but a very thin support layer compromises the membrane mechanical strength. Recently, researchers have applied different carbon-based nanomaterials to enhance water flux, fouling propensity, and mechanical strength of the FO membrane. This work reviews advancement in the FO membrane fabrication using carbon nanomaterials to improve the membrane characteristics. Despite a large number of laboratory experiments, carbon-based nanomaterials in the FO membrane are still at the early-stage of laboratory investigation and no commercial products are available yet. The study also reviews the main challenges that limit the application of carbon-based nanomaterials for FO membranes. 2020 Elsevier B.V.This publication was supported by Qatar University grant number QUCG-CAM-19/20-4 and NPRP grant 10-0117-170176 from the Qatar National Research Fund (a member of Qatar Foundation ). PhD candidate Sudesh Yadav would like to acknowledge scholarship support from University of Technology Sydney under UTS President's Scholarship and International Research Scholarship (IRP). The findings achieved herein are solely the responsibility of the authors.Scopu

Simulation Study of Utilizing X-ray Tube in Monitoring Systems of Liquid Petroleum Products

Radiation-based instruments have been widely used in petrochemical and oil industries to monitor liquid products transported through the same pipeline. Different radioactive gamma-ray emitter sources are typically used as radiation generators in the instruments mentioned above. The idea at the basis of this research is to investigate the use of an X-ray tube rather than a radioisotope source as an X-ray generator: This choice brings some advantages that will be discussed. The study is performed through a Monte Carlo simulation and artificial intelligence. Here, the system is composed of an X-ray tube, a pipe including fluid, and a NaI detector. Two-by-two mixtures of four various oil products with different volume ratios were considered to model the pipe’s interface region. For each combination, the X-ray spectrum was recorded in the detector in all the simulations. The recorded spectra were used for training and testing the multilayer perceptron (MLP) models. After training, MLP neural networks could estimate each oil product’s volume ratio with a mean absolute error of 2.72 which is slightly even better than what was obtained in former studies using radioisotope sources