Temperature Polarization Coefficient Research Articles

Process intensification in the direct contact membrane distillation (DCMD) desalination by patterning membrane surface: A CFD study

In this research, the impact of pattern geometry on the intensification of the performance of surface patterned membranes for saline water desalination by direct contact membrane distillation (DCMD) is investigated by computational fluid dynamics (CFD) simulation. The Comsol Multiphysics software was applied to solve the governing transport equations for heat, momentum, and mass transfer. The result of the model was validated by the published experimental data, and the maximum deviation was less than 10%. The target was to maximize the permeate flux by altering surface pattern geometry and dimensions. Based on the previous studies, a prism pattern was chosen in this work, and the influences of pattern type (3 types), pattern dimension (25-150 µm valley depth), and the distance between the valleys (0-400 µm) were studied on the temperature polarization coefficient (TPC) and DCMD permeate flux. The results showed that the pattern with a valley depth of 25 µm and a distance between the valleys of 300 µm had the best performance in DCMD operation. In this situation and feed temperature of 80°C, a TPC of 0.78 and a water flux of 49.3 kg/m2.h were attained. The characteristics of flow close to the patterned membrane surface were also investigated, and it was observed that there are weak shear stresses in the lower zone of the valleys, while stronger shear stresses are created in the upper regions that are responsible for improving the TPC and water flux in the patterned membranes.

Enhanced solar desalination with photothermal hydrophobic carbon nanotube-infused PVDF membranes in air-gap membrane distillation

This work aims to increase the efficiency of the solar powered-air gap membrane distillation (SP-AGMD) process; a desalination method driven by solar energy, providing an eco-friendly and sustainable approach to addressing global water shortages. The innovation lies in integrating photothermal hydrophobic multiwalled carbon nanotubes (h-MWCNTs), in varying weight percentages from 5 % to 60 %, into polyvinylidene fluoride (PVDF) membranes using the phase inversion membrane fabrication technique. The h-MWCNTs were synthesized through oxidation and functionalization with oleylamine (OL) to improve their photothermal properties. Their successful integration was confirmed via scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The h-MWCNTs-based SP-AGMD membranes were further evaluated for wettability, liquid entry pressure (LEP), surface temperature, and solar absorbance, demonstrating significant solar light absorption and localized surface heating. This generated the necessary driving force for the AGMD process. Performance metrics such as vapor flux, salt rejection, specific thermal energy consumption, photothermal efficiency, and temperature polarization (TP) coefficient were significantly improved, especially with a 20 % h-MWCNTs addition, which tripled the solar-energy-driven flux and increased photothermal efficiency by 326 % under standard solar conditions, compared to unmodified membranes. All h-MWCNTs-based SP-AGMD membranes achieved over 99 % salt rejection. Lastly, the membranes were tested with real seawater to confirm their applicability for desalination. This photothermal approach offers a scalable, sustainable solution for water purification, making a significant advancement in membrane distillation technology.

Optimizing fouling mitigation in membrane distillation by controlled microbubble size and concentration

Fouling control strategies play a crucial role in membrane distillation (MD) process, primarily due to the significant limitation of fouling during the scaling-up process. The utilization of microbubbles (MBs) aeration has exhibited promising potential in mitigating membrane fouling when treating high salinity wastewater. Aeration can introduce gas-liquid two-phase flow on the membrane surface, thereby increasing the membrane surface shear force. The mechanism of aeration technology for controlling fouling includes the following points: introduction of gas-liquid two-phase flow; physical substitution of concentration polarization layer; pressure pulses caused by bubbles flowing through the membrane surface and increasement of the cross flow velocity. This research aims to optimizing the effect of air MBs with different concentrations and sizes introduced in the feed side on membrane fouling control, we creatively used the method of releasing pressure gradiently to achieve size regulation of MBs within a certain range for the first time, firstly regulated the generation of MBs by manipulating gas flow rate and release pressure. Under the optimal condition of 40 mL/min and 0.6 MPa, it will yield concentration of 1.58 × 104/mL and D50 Sauter size of 64.69 μm MBs with pure water permeance flux of 12.32 kg/(m2·h). It was observed that higher gas flow rates primarily increased MBs concentration, while lower pressures predominantly reduced MBs size through the method of inline imaging. Experimental results indicated that introduction of MBs can slightly improve the temperature polarization coefficient and mass transfer coefficient under different operating modes. Consequently, further investigations focused on the influence of MBs characteristics on different fouling control. All conditions reach 99 % rejection for inorganic salt and HA. This study provided empirical evidence that higher concentration and larger size of MBs intensify the gas-liquid two-phase flow disruption and exhibit a better shear effect on scaling phenomena, which yield advantageous outcomes in terms of augmenting permeance flux and water vapor production, with permeance flux increased from 40.12 % to 55.42 % for inorganic fouling and increased from 68.35 % to 80.15 % for inorganic and HA fouling. These results were confirmed via membrane surface using scanning electron microscopy and energy dispersive spectroscopy. In summary, this research aided in identifying appropriate operating conditions for mitigating inorganic and composite scaling by implementing air-infused MBs in direct contact membrane distillation (DCMD), which provides scientific and technical guidance for controlling fouling in MD in practical applications.

Beyond the surface: Understanding temperature polarisation in DCMD membranes through varied operational parameters

Conventionally, a single Temperature Polarisation Coefficient (TPC) value is calculated to quantify Temperature Polarisation (TP). In this research, the extent of polarisation is investigated by capturing temperature profiles at specific points along a MD membrane using miniature thermocouples, eliminating the need for TPC calculations. The extent of polarisation at a point is affected by two contributory factors, namely the proximity of flow inlets and the difference in vapour pressure across the membrane at that point. Under this direction, this work examined the influence of permeate temperature, feed salinity, and flow direction on the development of the temperature profiles. Our analysis revealed an elevation in TP on both sides of the membrane when the permeate temperature was increased. In addition, changes in feed salinity had a very minute impact on the development of the temperature profiles. By comparing the cocurrent and counter-current flow, the influence of the two contributory factors was further proved, with counter-current flow working better for long membrane modules. Furthermore, an investigation on the symmetricity of polarisation across the membrane revealed asymmetricity depends on the operating conditions, especially direction of flow. The asymmetricity was infinitesimal at low inlet temperature differences for cocurrent flow.

Enhancing the Permeate Flux Improvement of Direct Contact Membrane Distillation Modules with Inserted S-Ribs Carbon-Fiber Filaments.

Three widths of manufacturing S-ribs carbon-fiber filaments acting as turbulence promoters were implemented into the flow channel of direct contact membrane distillation (DCMD) modules to augment the permeate flux improvement in the present study. Attempts to reduce the disadvantageous temperature polarization effect were made by inserting S-ribs turbulence promoters in improving pure water productivity, in which both heat- and mass-transfer boundary layers were diminished due to creating vortices in the flow pattern and increasing turbulence intensity. The temperature polarization coefficient ttemp was studied and found to enhance device performance (less thermal resistance) under inserting various S-ribs carbon-fiber thicknesses and operating both cocurrent- and countercurrent-flow patterns. The permeate fluxes in the DCMD modules with inserted S-ribs carbon-fiber turbulence promoters were investigated theoretically by developing the mathematical modeling equations and were conducted experimentally with various design and operating parameters. The theoretical predictions and experimental results exhibited a great potential to considerably achieve permeate flux enhancement in the new design of the DCMD system. The DCMD module with inserted S-ribs carbon-fiber turbulence promoters in the flow channel could provide a relative permeate flux enhancement up to 37.77% under countercurrent-flow operations in comparisons with the module of using the empty channel. An economic consideration on both permeate flux enhancement and power consumption increment for the module with inserted S-ribs carbon-fiber filaments was also delineated.

Experimental and Simulation Study of Solar-Powered Air-Gap Membrane Distillation Technology for Water Desalination.

This work aimed to investigate temperature polarization (TP) and concentration polarization (CP), which affect solar-powered air-gap membrane distillation (SP-AGMD) system performance under various operating conditions. A mathematical model for the SP-AGMD system using the experimental results was performed to calculate the temperature polarization coefficient (τ), interface temperature (Tfm), and interface concentration (Cfm) at various salt concentrations (Cf), feed temperatures (Tf), and flow rates (Mf). The system of SP-AGMD was simulated using the TRNSYS program. An evacuated tube collector (ETC) with a 2.5 m2 surface area was utilized for solar water heating. Electrical powering of cooler and circulation water pumps in the SP-AGMD system was provided using a photovoltaic system. Data were subjected to one-way analysis of variance (ANOVA) and Spearman's correlation analysis to test the significant impact of operating conditions and polarization phenomena at p < 0.05. Statistical analysis showed that Mf induced a highly significant difference in the productivity (Pr) and heat-transfer (hf) coefficients (p < 0.001) and a significant difference in τ (p < 0.05). Great F-ratios showed that Mf is the most influential parameter. Pr was enhanced by 99% and 146%, with increasing Tf (60 °C) and Mf (12 L/h), respectively, at a stable salt concentration (Cf) of 0.5% and a cooling temperature (Tc) of 20 °C. Also, the temperature increased to 85 °C when solar radiation reached 1002 W/m2 during summer. The inlet heat temperature of AGMD increased to 73 °C, and the Pr reached 1.62 kg/(m2·h).

Experimental investigation of temperature polarisation by capturing the temperature profile development over DCMD membranes

Temperature polarisation (TP) is a major drawback limiting the global acceptance of membrane distillation (MD) technology. TP is typically quantified using a dimensionless index known as Temperature Polarisation Coefficient (TPC). TPC has significant limitations, whereby it cannot be used to compare different MD configurations or design conditions, nor to analyse the TP phenomenon along the membrane. In this research, the temperature profile over and along a lengthy DCMD membrane has been measured under various operational conditions, where its impact on TP has been explored for the first time. A specialised DCMD membrane cell was manufactured to capture temperature profiles, both along and over the membrane surfaces, using miniature thermocouples. The effects of flow rate and feed temperature were investigated on the temperature profiles. The results showed that the extent of TP was not constant along the membrane, and that the temperature profile was not symmetrical across the feed and permeate side, predominantly due to the effects of the inlet and outlet on the flow. The TPC value calculated using the conventional method was not able to accurately reflect the TP phenomenon along the membrane, indicating TPC to be an ineffective tool to study TP along the membrane.

A numerical analysis of the electromagnetic field effect on direct contact membrane distillation performance

Using an advanced CFD model, this study attempts to determine how electromagnetic field (EMF) affects the performance of the direct contact membrane distillation (DCMD) process. The influence of electromagnetic fields (EMF) on the permeate flow, evaporation efficiency (EE), and temperature polarization coefficient (TPC) of the DCMD process are studied using a thorough theoretical model linked with a CFD model. Experiments conducted in-house with and without the EMF influence are used to verify the CFD model. High magnetic potency propagates the turbulence in the feed channel, hence boosting the driving force and transport phenomena for vapor transport to the permeate side. Permeate flux increased by 30%, and EE increased by 15% when the magnetic field strength was raised from 0 to 0.5 T, particularly at a lower intake feed velocity (0.02 m/s) and temperature of 333.05 K. In contrast, with the same magnetic potency (0.5 T) at a higher velocity at an input feed temperature, there is less improvement in EE (5%) and permeate flux (12%) due to the elevated turbulence intensity at high feed velocity. This research contributes to studies aimed at elucidating how electromagnetic fields affect separation processes such as MD, opening the door for more tuning and use of the fascinating phenomenon.

Effect of wavy corrugations on the performance enhancement of direct contact membrane distillation modules: A numerical study

This study employs three-dimensional (3D) computational fluid dynamics (CFD) simulations to investigate the influence of corrugations on direct contact membrane distillation (DCMD) modules. The accuracy of 3D CFD simulations is validated by the comparison of water flux and temperature polarization coefficient (TPC) against literature data for empty and spacer-filled DCMD modules. The dusty gas model is used to predict the permeate flux as a function of temperature and pressure over the surface of the membrane. We consider single and double sinusoidal corrugated membranes and examine the performance of DCMD membranes in terms of TPC, concentration polarization coefficient (CPC), power number (Pn), and Nusselt number (Nu) against various corrugation geometrical parameters. These parameters include the amplitude, streamwise, and spanwise frequency of corrugation waves. Our results show that corrugated membranes can successfully improve the membrane system by disrupting the boundary layer by an intense secondary flow. The mechanism works the best at high flow rates. Our results suggest that singly corrugated membranes improve the water flux and TPC by 32% and 25% at Re=1500. Also, doubly corrugated membranes provide 45% and 36% improvements in water flux and TPC at the same Reynolds number.

Performance enhancement for membrane distillation by introducing insoluble particle fillers in the feed

Temperature and concentration polarizations are typical near-surface phenomena that limit the performance of membrane distillation. An effective method for enhancing the performance of membrane distillation is to mechanically disturb or break the polarization effect near the membrane surface. In this study, we focused on disturbing the flow boundary layer formed near the membrane surface to eliminate the influence of temperature and concentration polarizations on the membrane distillation performance by introducing insoluble particles as fillers into the feed. It is believed that the sliding/scrolling of insoluble particle fillers on the membrane surface is a practical approach for breaking the boundary layer on the membrane surface and eliminating near-surface polarization. The effects of breaking the near-surface polarization on the membrane distillation performance were systematically investigated via experiments under various conditions and verified with related computational fluid dynamics simulations. The test results demonstrated that the permeate flux, temperature polarization coefficient, and system efficiency of membrane distillation can all be improved with particle fillers. The permeate flux does not increase indefinitely with the rise of particle filler mass flow rate. Moreover, the incorporation of particle fillers is especially effective in enhancing the permeate flux at low feed concentration.

Understanding flow dynamics in membrane distillation: Effects of reactor design on polarization

Optimization and design of full-scale membrane distillation (MD) systems usually require Sherwood and Nusselt correlations that are developed from lab-scale systems. However, entrance effects in lab-scale systems can significantly impact heat, mass and momentum transfer in the reactor, therefore affect the accuracy of the developed experimental Sherwood and Nusselt correlations. Here, Computational Fluid Dynamics (CFD) simulations using OpenFOAM are performed to understand the effects of right-angled bends and inlet design on flow dynamics, temperature and concentration polarization in MD systems. Simulation results show that the presence of right-angled bends and inlets with sudden expansions lead to the formation of Dean vortices. Dean vortices enhance perpendicular mixing in MD systems and reduce both temperature and concentration polarization. Temperature and concentration polarization coefficients in MD systems with right-angled bends and inlets with sudden expansions vary significantly for the same volumetric flow rate. Our studies show that lab-scale systems with the same volumetric flow rate but different designs lead to significantly different Nusselt and Sherwood correlations. This study demonstrates the importance of CFD-informed design of lab-scale systems to minimize entrance effects and suppress Dean vortices for consistent model development and calibration across multiple scales.

Distillation performance in a novel minichannel membrane distillation device

To lessen the polarization effect in membrane distillation and increase the permeation flux, a minichannel membrane distillation device (MMDD) was developed. The influence of the gap size, feed temperature, flow rate, and flow type on the permeation flux during membrane distillation was investigated. The permeation flux was enhanced by reducing the gap size, increasing the feed temperature and feed flow rate, and employing countercurrent flow. Based on the heat and mass transfer model of the membrane distillation process, a mathematical model for predicting in the influence of the membrane parameters on the temperature polarization coefficient and thermal efficiency in the MMDD was constructed. The theoretical values were verified to be in good agreement with the experimental data. Using the MMDD, the permeation flux and the temperature polarization coefficient increased by 160 % and 35 %, compared with those of conventional membrane distillation devices, respectively. Thus, it is proved that the proposed MMDD effectively eliminates the polarization effect, boosts the thermal efficiency, and improves the efficacy of membrane distillation performance.

Electrohydrodynamic atomization of CNT on PTFE membrane for scaling resistant membranes in membrane distillation

In this study, an electrohydrodynamic atomization or electrospraying technique is used for the uniform deposition of carbon nanotubes (CNT) on a commercially available PTFE membrane and employed for Membrane Distillation (MD) process. Modified PTFE-CNT membrane was characterized for water contact angle, liquid entry pressure (LEP), pore size distribution, and surface morphology. The electrospray coating of CNT on the PTFE membrane enhances the turbulence and thereby the temperature polarization coefficient (TPC). The pore size of the micropatterned PTFE-CNT membrane has been reduced and pore size distribution has been narrowed compared to the PTFE membrane. Field-effect scanning electron microscopy images of the membranes were observed before and after the MD process. Functionally graded PTFE-CNT membrane showed superior desalination performance compared to the PTFE membrane with less amount of cake layer formation on the membrane surface. Water vapor flux remained constant during 24-h continuous MD process operation with 99.99% rejection of inorganic salts.

Numerical investigation on mass and heat transfer performance for novel vacuum membrane distillation modules enhanced by semicircular spacers

Semicircular spacers are creatively introduced into the micro vacuum membrane distillation (VMD) modules for the purpose of modifying flowing field, decreasing mass transfer resistance and enhancing water production. A two-dimensional computational fluid dynamics model is developed to conduct the performance evaluation of rectangular micro-VMD modules. Calculated results indicate that novel VMD modules obtain remarkable improvement in terms of transmembrane mass flow rate. Local velocity and vorticity magnitude around the semicircular spacers increase with augment of the dimension of semicircular spacers as revealed in flow performance evaluation. Thermal performance displays that temperature distribution evolves into uniform when the semicircular spacers are introduced and noticeable improvement can be observed in transmembrane heat flux rate, local temperature and temperature polarization coefficient (TPC) performance. Whereas, Nu number varies in a certain range depending on the configuration of semicircular spacers. This paper further discloses the effect of operating parameters on the mass transfer, heat transfer and TPC performance. It is theoretically found that performance of proposed VMD modules is more sensitive to feed inlet temperature rather than feed inlet velocity. In conclusion, semicircular spacers are believed to be effective strategies to enhance performance of micro-VMD modules, with remarkable improvement to flow field, heat and mass transfer.

Electrosprayed CNTs on Electrospun PVDF-Co-HFP Membrane for Robust Membrane Distillation.

In this investigation, the electrospraying of CNTs on an electrospun PVDF-Co-HFP membrane was carried out to fabricate robust membranes for the membrane distillation (MD) process. A CNT-modified PVDF-Co-HFP membrane was heat pressed and characterized for water contact angle, liquid entry pressure (LEP), pore size distribution, tensile strength, and surface morphology. A higher water contact angle, higher liquid entry pressure (LEP), and higher tensile strength were observed in the electrosprayed CNT-coated PVDF-Co-HFP membrane than in the pristine membrane. The MD process test was conducted at varying feed temperatures using a 3.5 wt. % simulated seawater feed solution. The CNT-modified membrane showed an enhancement in the temperature polarization coefficient (TPC) and water permeation flux up to 16% and 24.6%, respectively. Field-effect scanning electron microscopy (FESEM) images of the PVDF-Co-HFP and CNT-modified membranes were observed before and after the MD process. Energy dispersive spectroscopy (EDS) confirmed the presence of inorganic salt ions deposited on the membrane surface after the DCMD process. Permeate water quality and rejection of inorganic salt ions were quantitatively analyzed using ion chromatography (IC) and inductively coupled plasma-mass spectrometry (ICP-MS). The water permeation flux during the 24-h continuous DCMD operation remained constant with a >99.8% inorganic salt rejection.

Computational fluid dynamics simulations of solar-assisted, spacer-filled direct contact membrane distillation: Seeking performance improvement

Significant downstream performance reduction and concentration polarisation reduce direct contact membrane distillation (DCMD) efficiency. These challenges are not well researched since they are difficult to implement experimentally and numerically. Hence, this study examined the impact of solar absorbers and different spacer filaments upon DCMD performance. A 2D computational fluid dynamics model that considered simultaneous mass and heat transfer across the membrane and throughout the channels was developed to simulate water flux in DCMD modules under the use of solar absorbers and spacer filaments of various designs. The simulation outcomes were in excellent agreement with experimental results provided by two different studies, with the assisted solar absorber module and the spacer-filled module deviating <5 % and 3 % from the experimental results, respectively. A module equipped with the solar absorber membrane enhanced the DCMD performance better than a module with a solar absorber plate. The results also illustrated that a module with cylindrical detached spacer filaments improved DCMD performance more than a module with rectangular and semicircular attached spacers. Finally, it was shown that a module equipped with an integrated developed spacer and solar absorber membrane significantly enhanced water flux and both concentration and temperature polarisations, specifically when the inlet velocity was increased. Water flux and the temperature polarisation coefficient increased by 220 % in the integrated module, and the concentration polarisation coefficient decreased by 10 %. Moreover, the developed module resulted in a substantial increase in downstream performance.

Modelling and simulation of flux prediction and salinity variation in direct contact membrane distillation for seawater desalination and brine treatment

As one of the state-of-art desalination technologies, membrane distillation (MD) has been widely studied in recent years. In order to better control the performance of the MD, a new model that can predict the membrane surface temperatures, permeate flux as well as salinity variation with the operating time has been proposed in this study. Using the model, impacts of operating parameters such as bulk temperature, flow rate, different membrane materials and feed salinity on the permeate flux as well as the efficiency of driving force were simulated. The results of the simulations indicate that feed temperature, feed flow rate and membrane pore size have the most significant influence on the permeate flux. However, the feed and permeate flow rates have the highest impacts on the temperature polarization coefficient (TPC) which has the highest value of 0.68 under certain conditions. Besides, the simulations predicted that the water recovery from the MD for the seawater and the desalination brine at the saturation point of NaCl to be 86.8 % and 72.1 %, respectively. Finally, the salinity variations with operating time were also simulated and the new model would be vital for the salinity control in desalination processes such as membrane distillation crystallization.

Effect of Teflon-Coated PVDF Membrane on the Performance of a Solar-Powered Direct Contact Membrane Distillation System

The present study dealt with the generation of freshwater through the direct contact membrane distillation (DCMD) technique, powered by an evacuated tube solar collector (ETSC). The major objective of the present work was to determine the optimum conditions of fluid flow rate and temperature for maximum freshwater productivity across both the feed and permeate sides of the membrane module. A flat hydrophobic membrane composed of polyvinylidene fluoride (PVDF) coated with Teflon was utilized for the DCMD process. The rate of freshwater production was examined with the variation in the feed/permeate flow rates (from 3 to 7 LPM) and feed temperature (from 45 °C to 75 °C) for a constant permeate-side temperature of 30 °C. The experimental results indicated that a maximum freshwater productivity of 45.18 kg/m2h was achievable from the proposed system during its operation with a high solar heated inlet feed temperature of 75 °C and mass flow rates of 7 LPM across both sides of the membrane. Further, a detailed assessment of the performance parameters indicated that the present solar-powered DCMD system exhibited a maximum evaporative efficiency of about 80% and temperature polarization coefficient (TPC) of 0.62 respectively.

Computational fluid dynamics based numerical simulations of heat transfer, fluid flow and mass transfer in vacuum membrane distillation process

Abstract In this study, we developed a comprehensive two-dimensional computational fluid dynamics (CFD) model using COMSOL™ Multiphysics to describe and simulate heat transfer, mass transfer and fluid flow in the flat sheet vacuum membrane distillation (VMD) under laminar flow conditions. A combination of Knudsen and Poiseuille flow was applied to study mass transfer across the membrane. The effect of variation of Reynolds number, inlet feed temperature and degree of vacuum on different parameters (mass flux, temperature polarization coefficient- TPC, concentration polarisation, heat transfer coefficient) was studied. There was a positive impact of the Reynolds number (50–200) on mass flux (13.15%), heat transfer coefficient (2.64%) and TPC (1.42%), while CPC decreased by 56.63%. The increment in the heat transfer coefficient was due to fluid mixing on the feed side, while the increment in the TPC was due to a higher temperature gradient across the membrane surfaces. The increment in the feed temperature (323–343 K) resulted in an increase in mass flux by 132.9%, while TPC decreased from 0.98 to 0.90. The degree of vacuum (640–750 mm Hg) increased mass flux and heat transfer coefficient by 72.52 and 425.83%, respectively, while the TPC decreased by 8.81%. The feed temperature was the most sensitive parameter with respect to mass flux. The developed CFD model was validated with in-house experimental results with reasonable accuracy.

Sonicated direct contact membrane distillation: Influence of sonication parameters

The effect of sonication on the performance of the direct contact membrane distillation (DCMD) is studied in this work. A sonicated DCMD module equipped with a commercial PTFE membrane is built and tested in an immersed temperature-controlled water bath. High fidelity transient and thermally conjugated CFD model is also developed for the DCMD unit accounting for the sonication. Flow metrics, including temperature polarization coefficient (TPC), heat- and mass- flux under different sonication frequencies and amplitudes were evaluated. Parametric study showed a clear improvement in the DCMD system metrics and more pronounced at higher temperature. It was observed that the application of sonication impedes the development of both kinetic and thermal boundary layers due to ultrasonic-induced mixing. The results showed that the application of sonication to DCMD at the intensity of 4525 W/m2 resulted in increase of mass flux from 4.25 L/m2.h to 8.1 L/m2.h corresponding to 90% increase. It is economically unviable due to electrical power demand, i.e., ~ 35 kW.h/m3 (~$5/m3), but can be feasible below 474 W/m2 demanding 3 kW.h/m3 (nearly $0.42/m3). It was also observed that an interesting equivalence exists between the effect of acoustic amplitude and acoustic frequency on the performance of DCMD. For example, sonication at 1 kHz with 0.5 μm amplitude produced similar results, in terms of mass flux and TPC, as sonication at 5 kHz with 0.1 μm amplitude.