Experimental Investigation of Heat Transfer Correlation for Direct Contact Membrane Distillation

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Quoc Linh Ve ◽  
Kawtar Rahaoui ◽  
Mohammed Bawahab ◽  
Hosam Faqeha ◽  
Abhijit Date ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Copper Plate ◽  
Heat Transfer Correlation ◽  
Hydrophobic Membrane ◽  
Flow Channels ◽  
Direct Contact Membrane Distillation ◽  
Turbulent Flow Regime

Abstract This paper presents an experimental investigation of heat transfer in direct contact membrane distillation (DCMD) flow channels with and without the spacer. In this experiment, the usual hydrophobic membrane of DCMD is replaced by a copper plate to eliminate mass transfer. The study shows the most appropriate heat transfer correlations for empty channel cases with different channel heights and flow rates. For the case with the spacer in the flow channels, two spacer materials are investigated: nonwoven plastic and woven stainless steel. The paper presents the most appropriate heat transfer correlation for both these spacer materials. Further, the paper presents finding with two more spacer materials, woven fiberglass and aluminum spacer. It is found that the most appropriate heat transfer correlation for these materials is in the turbulent flow regime although the experimentally estimated Reynolds number suggests laminar flow is presented.

scholarly journals Performance modelling of direct contact membrane distillation using a hydrophobic/hydrophilic dual-layer membrane

2021 ◽  
Author(s):  
Inci Boztepe ◽  
Stephen Gray ◽  
Jianhua Zhang ◽  
Jun-De Li
Keyword(s):  
Mass Transfer ◽  
Thermal Efficiency ◽  
Direct Contact ◽  
Single Layer ◽  
Membrane Distillation ◽  
Experimental Results ◽  
Conductive Heat ◽  
Hydrophobic Membrane ◽  
Direct Contact Membrane Distillation ◽  
Layer Membrane

Abstract HFP-co-PVDF/N6 hydrophobic/hydrophilic dual-layer membrane was used to study desalination with direct contact membrane distillation (DCMD). A one-dimensional (1-D) model was proposed to predict the flux and thermal efficiency. Heat and mass transfer equations were solved numerically for the combined hydrophilic and hydrophobic layers. The membrane characteristics of the hydrophobic layer were considered for the calculation of the mass transfer coefficients, while the hydrophilic layer was ignored since it was assumed to be filled with water. However, the hydrophilic layer was taken into account during the calculations of conductive heat transfer. Therefore, the equations are different, compared to single-layer hydrophobic membranes. It was found that with the same hydrophobic membrane characteristics, the single-layer membranes performed with better flux and thermal efficiency than the dual-layer membranes. Furthermore, the improvement of flux and thermal efficiency by an addition of the hydrophilic layer has not been observed experimentally, and it is suggested that the improved performance for dual-layer membranes reported previously is due to improved permeability by using thinner and more porous hydrophobic layers that can be mechanically reinforced by the hydrophilic layer. The validation of the model was conducted by comparing the experimental results for single- and dual-layer membranes with the modelling results. The predicted flux and thermal efficiency by the modelling were within 10% error to the experimental results.

Exergetic Relationship Between the Thermal Properties of Direct Contact Membrane Distillation

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
D. Perdue ◽  
L. Chen ◽  
L. Schaefer
Keyword(s):  
Thermal Properties ◽  
Direct Contact ◽  
Chemical Potential ◽  
Direct Simulation Monte Carlo ◽  
Monte Carlo Analysis ◽  
Membrane Distillation ◽  
Flow Speed ◽  
Hydrophobic Membrane ◽  
Direct Contact Membrane Distillation ◽  
Temperature Polarization

Abstract Direct contact membrane distillation (DCMD) is a process that has shown promise within the field of desalination due to its less energy intensive methods and widespread applications. DCMD is a thermally driven microfiltration separation process that operates on the principle of vapor–liquid equilibrium conditions where heat and mass transfer occur simultaneously. Fundamentally, DCMD is based on a porous hydrophobic membrane separating the hot solution (feed) from the cold solution (permeate) where desalinated water condenses. The membrane interfacial temperatures determine the vapor pressure difference across the membrane. In this work, a direct simulation Monte Carlo analysis is employed to investigate how the exergy of the system relates to some key thermal properties, namely, the temperature polarization coefficient (TPC) and the thermal efficiency (TE), as other parameters are changed, such as feed temperature, flow speed, and membrane porosity. Through molecular simulation, phase equilibrium is reached by calculating the chemical potential at the membrane interface and the entropy of the system is found. Since exergy is a function of entropy, enthalpy, and temperature, the amount of useful work is calculated. Finally, exergy is compared to the TPC and TE as the flowrate and porosity are varied. We demonstrate that with these exergy calculations, the information about the thermal relationship between microscopic and macroscopic parameters will improve future experimental work.

scholarly journals Influence of Hydraulic Pressure on Performance Deterioration of Direct Contact Membrane Distillation (DCMD) Process

Membranes ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 37 ◽  
Author(s):  
Seung-Min Park ◽  
Sangho Lee
Keyword(s):  
Mass Transfer ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Hydraulic Pressure ◽  
Transfer Coefficients ◽  
Hydrophobic Membrane ◽  
Mass Transfer Coefficients ◽  
Efficient Operation ◽  
Direct Contact Membrane Distillation

Direct contact membrane distillation (DCMD) is a membrane distillation (MD) configuration where feed and distillate directly contact with a hydrophobic membrane. Depending on its operating conditions, the hydraulic pressures of the feed and distillate may be different, leading to adverse effects on the performance of the DCMD process. Nevertheless, little information is available on how hydraulic pressure affects the efficiency of DCMD. Accordingly, this paper investigates the effect of external hydraulic pressure on the process efficiency of DCMD. Gas permeabilities of MD membranes were measured to analyze the effect of membrane compaction by external pressure. Mass transfer coefficients were calculated using experimental data to quantitatively explain the pressure effect. Experiments were also carried out using a laboratory-scale DCMD set-up. After applying the pressure, the cross-sections and surfaces of the membranes were examined using a scanning electron microscope (SEM). Results showed that the membrane structural parameters such as porosity and thickness were changed under relatively high pressure conditions (>30 kPa), leading to reduction in flux. The mass transfer coefficients were also significantly influenced by the hydraulic pressure. Moreover, local wetting of the membranes were observed even below the liquid entry pressure (LEP), which decreased the rejection of salts. These results suggest that the control of hydraulic pressure is important for efficient operation of DCMD process.

scholarly journals An experimental heat transfer investigation of using spacer in direct contact membrane distillation

2019 ◽  
Vol 160 ◽  
pp. 223-230 ◽  
Author(s):  
Quoc Linh Ve ◽  
Kawtar Rahaoui ◽  
Mohammed Bawahab ◽  
Hosam Faqeha ◽  
Abhijit Date ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Experimental Heat ◽  
Direct Contact Membrane Distillation ◽  
Experimental Heat Transfer
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