Thermodynamics analysis of a direct contact membrane distillation with/without heat recovery based on experimental data

Najib, Abdullah; Orfi, Jamel; Esrafili, Ali; Saleh, Jehad

doi:10.1016/j.desal.2019.05.009

Cited by 42 publications

(13 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The gain output ratio (GOR) is a standard performance indicator to express the maximum heat requirement for the desalination process. It is commonly defined [7] as follows:…”

Section: Performance Indicatorsmentioning

confidence: 99%

“…Similarly, the specific thermal exergy consumption (STXC) has become an essential performance indicator for desalination systems. For a given V-MEMD unit, the STXC may be defined as follows [7]:…”

Section: Performance Indicatorsmentioning

confidence: 99%

“…Several pilot systems have been designed and constructed for membrane distillation powered by solar energy. Data and results reflecting the performance of MD systems in terms of production recovery ratio and energy efficiency under various operating conditions have been analyzed [5][6][7][8]. Bouguecha et al [5] investigated the performance and the thermal energy efficiency of a direct contact membrane distillation system (DCMD) integrated with solar collectors.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, the monthly average daily water production for December increases from 0.37 to 0.40 m 3 /day and the thermal efficiency from 31% to 45% when the dynamic operation mode is used compared to the steady-state mode. Najib et al [7] conducted a detailed experimental investigation on a direct contact membrane distillation (DCMD) unit with/without heat recovery (HR). In this study, they evaluated the specific energy consumption (SEC) and the specific exergy consumption (SXC) for the evaporator and the condenser under various experimental conditions to demonstrate the benefits of heat recovery.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

Najib

Orfi

Al-Ansary

et al. 2021

Water

View full text Add to dashboard Cite

A comprehensive study was conducted to elucidate the effect of operating conditions on the performance of a multi-effect vacuum membrane distillation pilot plant. A theoretical assessment of the energy and exergy efficiency of the process was achieved using a mathematical model based on heat and mass transfer, which was calibrated using experimental data obtained from the pilot plant. The pilot plant was a solar vacuum multi-effect membrane distillation (V-MEMD) module comprising five stages. It was found that a maximal permeate mass flux of 17.2 kg/m2·h, a recovery ratio of 47.6%, and a performance ratio of 5.38% may be achieved. The resulting gain output ratio (GOR) under these conditions was 5.05, which is comparable to previously reported values. Furthermore, the present work systematically evaluated not only the specific thermal energy consumption (STEC), but also the specific electrical energy consumption (SEEC), which has been generally neglected in previous studies. We show that STEC and SEEC may reach 166 kWh/m3 and 4.5 kWh/m3, respectively. We also observed that increasing the feed flow rate has a positive impact on the process performance, particularly when the feed temperature is higher than 65 °C. Under ideal operational conditions, the exergetic efficiency reached 21.1%, and the maximum fraction of exergy destruction was localized in the condenser compartment. Variation of the inlet hot and cold temperatures at a constant differential showed an interesting and variable impact on the performance indicators of the V-MEMD unit. The difference with the lowest inlet temperatures exhibited the most negative impact on the system performance.

show abstract

“…The gain output ratio (GOR) is a standard performance indicator to express the maximum heat requirement for the desalination process. It is commonly defined [7] as follows:…”

Section: Performance Indicatorsmentioning

confidence: 99%

Section: Performance Indicatorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

Najib

Orfi

Al-Ansary

et al. 2021

Water

View full text Add to dashboard Cite

show abstract

“…Limited knowledge exists on the effect of the current commercial membranes on DCMD performance [ 24 , 45 ]. For example, Vanneste et al [ 46 ] analysed 17 commercial membranes in terms of water flux and thermal efficiency [ 47 ] without discussing temperature and concentration polarisation. Therefore, another important aspect of this study was to analyse commercially available membranes in terms of their performance for DCMD application.…”

Section: Introductionmentioning

confidence: 99%

An Improved Modelling Approach for the Comprehensive Study of Direct Contact Membrane Distillation

Ansari

Kavousi²,

Helfer

et al. 2021

Membranes

View full text Add to dashboard Cite

Direct Contact Membrane Distillation (DCMD) is a promising and feasible technology for water desalination. Most of the models used to simulate DCMD are one-dimensional and/or use a linear function of vapour pressure which relies on experimentally determined parameters. In this study, the model of DCMD using Nusselt correlations was improved by coupling the continuity, momentum, and energy equations to better capture the downstream alteration of flow field properties. A logarithmic function of vapour pressure, which is independent from experiments, was used. This allowed us to analyse DCMD with different membrane properties. The results of our developed model were in good agreement with the DCMD experimental results, with less than 7% deviation. System performance metrics, including water flux, temperature, and concentration polarisation coefficient and thermal efficiency, were analysed by varying inlet feed and permeate temperature, inlet velocity, inlet feed concentration, channel length. In addition, twenty-two commercial membranes were analysed to obtain a real vision on the influence of membrane characteristics on system performance metrics. The results showed that the feed temperature had the most significant effect on water flux and thermal efficiency. The increased feed temperature enhanced the water flux and thermal efficiency; however, it caused more concentration and temperature polarisation. On the other hand, the increased inlet velocity was found to provide increased water flux and reduced temperature and concertation polarisation as well. It was also found that the membrane properties, especially thickness and porosity, can affect the DCMD performance significantly. A two-fold increase of feed temperature increased the water flux and thermal efficiency, 10-fold and 27%, respectively; however, it caused an increase in temperature and concertation polarisation, at 48% and 34%, respectively. By increasing Reynolds number from 80 to 1600, the water flux, CPC, and TPC enhanced by 2.3-fold, 2%, and 21%, respectively. The increased feed concentration from 0 to 250 [g/L] caused a 26% reduction in water flux. To capture the downstream alteration of flow properties, it was shown that the ratio of inlet value to outlet value of system performance metrics decreased significantly throughout the module. Therefore, improvement over the conventional model is undeniable, as the new model can assist in achieving optimal operation conditions.

show abstract

Understanding and enhancing the direct contact membrane distillation performance by modified heat transfer correlation

2020

Self Cite

View full text Add to dashboard Cite

The sensitivity of direct contact membrane distillation to feed temperatures and feed flow rate is investigated experimentally. At very low flow rates, the process becomes heat transfer limited where the thermal energy of the aqueous feed solution is lost by the conduction resistance minimizing the distillate production. At high flow rates, the film heat transfer coefficient for both liquid solutions increases, creating a larger temperature difference across the membrane boundaries. Hence, the mass fluxes increase linearly with the water flow rate. These findings are also assessed by simulating the heat and mass transfer equations that describe the membrane distillation (MD) thermo-physical operation. It is found that the underlying physics of the MD module must faithfully capture and explain the true process behaviour. Hence, a modified correlation for the Nusselt number is developed and tested.

show abstract

Thermodynamics analysis of a direct contact membrane distillation with/without heat recovery based on experimental data

Cited by 42 publications

References 37 publications

Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

An Improved Modelling Approach for the Comprehensive Study of Direct Contact Membrane Distillation

Understanding and enhancing the direct contact membrane distillation performance by modified heat transfer correlation

Contact Info

Product

Resources

About