Solar-powered Membrane Distillation System Research Articles

Parameter collaborative analysis and multi-objective optimization of a nanofluid filtered solar membrane distillation system using heat pump

The distributed solar powered membrane distillation (SPMD) system for water/electricity co-production is a valuable solution for relieving energy pressure in remote areas but it suffers from a complicated operation mechanism. This paper performs a comprehensive parameter analysis and user-oriented optimization on a nanofluid filtered solar membrane distillation system using heat pump to enhance its competitiveness. Response surface methodology is employed to examine the interactions of the influencing factors on the system performance, and the plots reveal significant interactions, particularly on equivalent specific thermal energy consumption (eSTEC). An artificial neural network is integrated with genetic algorithm to perform single and multi-objective system performance optimization. The results show that maximum system exergy efficiency, permeate flux and minimum eSTEC are 19.39 %, 35.8 kg·m−2·h−1 and 463.5 kWh·m−3, respectively. Furthermore, the technique for order preference by similarity to an ideal solution is utilized, based on performance indicator weight derived from the analytical hierarchy process, to offer a user-oriented optimal solution. It demonstrates that after optimization, the system exergy efficiency and permeate flux are improved by 9.9 % and 30.2 %, respectively, along with a reduction of eSTEC by 5.7 %. This research contributes to advancing solar-to-water/electricity efficiency and offering valuable insights for the development of SPMD systems.

Techno-economic analysis of solar-powered membrane distillation system with circulated permeate gap

This study investigates a novel integration of a circulated permeate gap membrane distillation (C-PGMD) module with flat plate solar collectors. The investigation is performed through a comprehensive performance study and techno-economic analysis, revealing unique insights and findings. The development of mathematical models enables the anticipation of system production and energy efficiency, capturing the employment of single and multistage C-PGMD modules under diverse design and operational conditions. Additionally, an innovative assessment of different powering modes, including solar-only, electrical-only, and hybrid solar-electrical is performed, which offers a unique perspective on system control and unit production costs. Results showed that circulating the permeate gap has significant effects on the permeate flux and the temperature of the solar tank such that the circulation rate controls the operation of the system. The revelation that increasing solar collector numbers amplifies productivity while reducing costs stands out as a noteworthy breakthrough. Cooling the system using a water source at ambient temperature is much recommended compared to cooling with chilled water. The pinnacle of this research lies in the proposal of a well-designed pilot hybrid-power 30-stage C-PGMD system, showcasing a remarkable achievement in reducing production costs to approximately 0.03 USD/Liter for 24-hour operation, predominantly powered by renewable energy sources. These novel findings redefine the landscape of integrated solar membrane distillation and pave the way for more sustainable and economically viable water desalination solutions.

A Review of Solar-Powered Membrane Distillation System: Concept Design and Development

A Review of Solar-Powered Membrane Distillation System: Concept Design and Development

Desalination via solar membrane distillation and conventional membrane distillation: Life cycle assessment case study in Jordan

In this paper, a comparative life cycle assessment (LCA) of a solar-powered membrane distillation (SPMD) plant in Aqaba, Jordan, is carried out in comparison with a conventional plant. It is assumed that the conventional membrane distillation plant (CMD) is similar to the SPMD plant, except for the associated materials and the energy source required to operate the plant. The LCA was conducted with five different scenarios of photovoltaic panel types to compare and examine their environmental impacts. Except for the global warming potential for some photovoltaic panel types, the results of this study show that the SPMD system powered by a-Si photovoltaic panel type is the best option as it has a lower environmental impact than CMD. As a next step, a comprehensive analysis of SPMD and CMD has been proposed, taking into account the detailed system design and end-of-life phases.

Improving the performance of solar powered membrane distillation systems using the thermal energy storage mediums and the evaporative cooler

The present experimental work aims to improve the performance of solar-powered tubular direct contact membrane distillation (TDCMD) systems. To investigate this idea, the membrane distillation system was integrated with thermal energy storage mediums and the evaporative cooler. The novelty of the present configuration is addition the energy storage mediums (phase change materials PCM) which represent the energy source to extend the water production time after sunset with high rates, as well as, improve the productivity in the period of low solar intensity before sunset. To obtain the influences of PCM on the performance of solar-assisted TDCMD with an evaporative cooler, the present configuration was tested first without PCM and again with utilizing the PCM within different test days under Egyptian climatic conditions. The experimental results show that as increases the rate of feed saltwater from 12 to 16 l/min, the accumulated productivity of solar-assisted TDCMD with evaporative cooler varying between 28.9 and 35.67 l/day while additional the PCM augments the productivity to 41.38–47.48 l/day, representing 33.11–43.18% enhancement in the productivity. Also, the gain output ratio of solar-assisted TDCMD with evaporative cooler varying between 0.77 and 0.93 while additional the PCM augments the gain output ratio to 1.123–1.25, representing 34.4–45.84% enhancement in the gain output ratio.

Fabrication and Performance Evaluation of Integrated Solar-Driven Membrane Distillation System with Serpentine-shape of Flat Plate Solar Collector for Seawater Desalination

Solar-powered membrane distillation (SPMD) system has gained its popularity in desalination application for past decade credit to the system efficiency in producing pure water and the utilization of renewable energy. However, most of the past SPMD works used commercial solar thermal collector (STC) as the thermal energy supply to the feed solution and the study only focused on the performance of the system in terms of flux and salt rejection. In this work, a self-made flat plate solar collector (FPSC) with the serpentine-shape pipe was designed and fabricated to study the effect of the STC towards the membrane performance. Before testing, a simulation work of the fluid flow inside the serpentine-shape pipe of the FPSC was analyzed using NX 10.0 computer-aided design simulation. After that, the efficiency of the self-made FPSC system was tested directly to sunlight in order to identify the maximum irradiance and the temperature of the feed solution. Due to the fluctuation of solar irradiance, the experimental setup of the SPMD system was tested using a solar simulator, and the performance was compared with the membrane distillation (MD) system without integration with FPSC system. Based on the simulation data, it can be concluded that the heat losses across the pipe are due to the slower fluid velocity and sudden pressure drop, which attributed to centripetal force and pressure differences. Meanwhile, the outdoor evaluation data showed that the temperatures of collector and water inside the feed tank could reach up to 84°C and 64°C, respectively when the maximum irradiance of 938 W/m2 was applied. For the performance evaluation between with and without the self-made FPSC system, it can be seen that only marginal difference can be observed for the permeate flux and salt rejection with an average difference of 6.06% and 1.29%, respectively.

Portable Solar-powered Membrane Distillation System to Solve Water and Energy Problems Simultaneously

With increasing human population, the demand for water as well as energy also increasing. This will lead to global water scarcity and energy crisis, due to limited freshwater resources and decreasing fossil fuel resources. The most potential solution to solve this water-energy problem is by using desalination technology powered by renewable energy like solar energy. This paper reports the design and development of a portable and stand-alone solar-driven desalination system. Due to portability, this system is expected to be transported to anywhere like remote areas. The system consists of three major parts, which are solar-thermal collector, solar photovoltaic (PV) panel, and Vacuum Multi-Effect Membrane Distillation (V-MEMD) unit as the main part of the system. In this paper, a small-scale operation test of the system was carried out and analyzed. The system run successfully for about 7 hours, which started at 09:00 AM. The feedwater used was brackish-water with conductivity of about 2500 μS/cm and the flowrate was maintained at 69 L/h. The system produced distillate/freshwater at average rate of 5.98 L/h. Whereas, the total distillate produced was approximately 34.8 L with conductivity of about Total Dissolved Solid (TDS) of 2.67 mg/L. The distillate flux of the current system was in the range of 3.2 – 5.2 L/m2.h.

Effect of intermittent operation on performance of a solar-powered membrane distillation system

Solar-powered membrane distillation is a promising technology for water desalination, especially in remote arid areas. However, the intermittent nature of solar irradiation restricts the operation of this technology to the daylight hours. Many studies tried to extend the daily operating period but at the expense of increasing complexity and cost. Therefore, most likely the stand-alone solar-powered system will be operated intermittently. This work is focused on studying the effect of the intermittent operation on a solar-powered MD system performance. A set of experiments were carried out on a bench-scale membrane distillation unit. A programmable temperature-controlled circulating bath was used to generate a feed temperature pattern similar to the temperature output of a solar heater in a real pilot solar-powered system. Different operation shutdown procedures (protocols) were examined to identify the best operation protocol for intermittent operation of MD system. The results showed fluctuations in the daily permeate flux and quality. Moreover, the permeate flux was observed to increase with the thermal expansion of the membrane material. There was a gradual deterioration in membrane module performance in terms of salt rejection when the module left to dry overnight. On the other hand, keeping the saline feed inside the module overnight was found to preserve the performance of the module. Ultrasonic cleaning was applied to the used hollow fiber membranes and found to help in recovering their hydrophobicity. This is observed by an increase in the contact angle values of these membranes from 77° to 98°.

Perspective of renewable desalination by using membrane distillation

As the water demand increases continuously, large capacities of desalination plant are added every year to meet freshwater demand. The higher carbon footprint of desalination raises concern on global climate change. The integration of desalination and renewable energy source could mitigate this water-energy nexus. Membrane distillation (MD) is a non-isothermal desalination process in which the low-grade heat is used as the driving force. Many researchers have tried to integrate solar energy and MD for sustainable water desalination. This article presents a comprehensive review of solar MD desalination to understand its current state of development. Solar powered MD systems have been investigated for last few decades. However, its commercialization is very limited due to low flux, high specific energy consumption and large collector area requirement. Further, this review presents the recent developments in MD membrane, innovative MD modules and the importance of optimization, which was able to improve the performance of solar MD.

Hybrid NMPC Applied to a Solar-powered Membrane Distillation System

This work proposes a hybrid control strategy for the optimal operation of a solar membrane distillation facility This kind of plants presents a hybrid nature allowing their operation in several modes, which must be properly selected according to the operating conditions. Thus, the control algorithm is based on a mixed logical dynamical characterization of the solar membrane distillation facility, combined with the application of a practical nonlinear model predictive control strategy for calculating the optimal control actions. The main objectives of the control system are to increase the operating temperature and the distillate production of the membrane distillation module, as well as the number of operational hours. For these goals, the control algorithm has to select the most appropriate operating mode and the optimal operating points in terms of water flow rate at each sampling time. Simulation results are presented for evidencing the benefits of the proposed control approach.

Design and fabrication of a portable and hybrid solar-powered membrane distillation system

This paper addresses the development of portable and hybrid solar-powered membrane distillation (SPMD) system for producing freshwater in remote arid and/or coastal areas like in Saudi Arabia. It is a stand-alone system that only uses renewable solar energy to operate. Thus, the system is highly suitable to be implemented in remote arid and coastal areas without infrastructures or connection to the grid (water and power), but blessed with abundant solar irradiation. Because the system is portable, it can also be used for emergency case like a natural disaster (e.g. tsunami). The system uses Vacuum Multi-Effect Membrane Distillation unit from Memsys to desalinate the seawater or brackish water. The SPMD system is a hybrid system that combines thermal collectors and photovoltaic (PV) panel. The thermal collectors convert solar irradiation into thermal energy to drive the Memsys process, whereas PV panel converts solar irradiation into electrical to power electrical equipment. The overall operations of the system were governed by Programmable Logic Controller. The innovation of this system is the design of a hybrid solar desalination system that is portable and reliable. The system can also be considered as a “green” and sustainable desalination technology. To study the performance of the system, small-scale tests have been conducted at the Engineering College – King Saud University, Saudi Arabia. The system ran successfully by only utilizing solar energy. The total volume distillate output during the test was approximately 70 L with an approximate conductivity of 4.7 μS/cm. The average distillate output rate was 11.53 L/h with the maximum of 15.94 L/h at noon time, whereas the distillate flux was in the range of 1.5–2.6 L/m2 h.

Autonomous solar powered membrane distillation systems: state of the art

AbstractBeing a basic element for the every existence of any form of life on earth, water is one of the most abundant resources on earth, covering three-fourth of the planet’s surface. However, there is a shortage of freshwater in many areas worldwide. Desalination seems to be the most suitable solution. Major conventional desalination processes, such as distillation and reverse osmosis, consume a large amount of energy derived from oil and natural gas as heat and electricity, which is responsible for harmful CO2 emission. Solar desalination has emerged as a promising renewable energy-powered technology for producing freshwater. Solar membrane distillation (MD) is the best option in decentralized regions with scattered population and lack of infrastructures jointly with hard climate conditions make it difficult or at least not cost-effective to scale down bigger desalination technologies, such as RO or MSF, designed for very big water productions. Moreover, MD compared to conventional thermal desalination...

An experimental review on coupling of solar pond with membrane distillation

The interest of using solar powered membrane distillation systems for desalination is growing worldwide due to the membrane distillation (MD) attractive features. This study experimentally investigates the utilization of direct contact membrane distillation (DCMD) coupled to a salinity-gradient solar pond (SGSP) for sustainable freshwater production and reduction of brine footprint on the environment. A mathematical model for heat and mass flux in the DCMD module and thermal model for SGSP are developed and coupled to evaluate the feasibility of freshwater production. The experiment results on RMIT University SGSP coupled with DCMD are presented. The feed stream of 1.3% salinity is heated up by the SGSP and circulated through DCMD module then injected to an evaporation pond. Also, a thermal energy system is used to recover heat from the outlet brine stream of DCMD and use it as preheating for inlet feed water stream. Results are compared and showed that if the flow is laminar, the connecting DCMD module to the SGSP could induce a marked concentration and temperature polarisation phenomenon that reduces fluxes. Therefor turbulence has to be created in the feed stream to reduce polarisation. Also, to reduce the environmental footprint, the brine is recirculated after passing through the heat exchanger.

A neural network-based optimizing control system for a seawater-desalination solar-powered membrane distillation unit

Several schemes have been proposed so far for coupling desalination processes with the use of renewable energy. One of their main drawbacks, however, is the nature of the energy source that requires a discontinuous and non-stationary operation, with some control and optimization problems. In the present work, a solar powered membrane distillation system has been used for developing an optimizing control strategy. A neural network (NN) model of the system has been trained and tested using experimental data purposely collected. Afterwards, the NN model has been used for the analysis of the process performance under various operating conditions, namely distillate production versus feed flow rate, solar radiation and cold feed temperature. On this basis, a control system that optimizes the distillate production under variable operating conditions has been developed, implemented and tested.

Economic evaluation of stand-alone solar powered membrane distillation systems

Economic evaluation was carried out to understand the main contributors to water production cost in solar-powered membrane distillation (SP-MD) systems. Three SP-MD systems (Direct Contact (DCMD), Air Gap (AGMD), and Vacuum (VMD)) were modeled and economically analyzed. A parametric study was conducted on the AGMD, the most frequently used SP-MD configuration, to understand the relationships between various design and operation parameters and water production cost. The parametric study results show that, in the AGMD system, increasing the feed inlet temperature had a significant effect in lowering the cost while higher feed flow rate resulted in increased water production cost. This study also shows that higher effective membrane length and lower air gap width and feed channel depth reduce the cost of water. Finally, the choice of MD configuration (AGMD, VMD, DCMD) in SP-MD systems will impact the final water cost.

Desalination by solar powered membrane distillation systems

Membrane distillation (MD) is a hybrid membrane-evaporative process which has been of interest for desalination. MD requires two types of energy, namely, low temperature heat and electricity. Solar collectors and PV panels are mature technologies which could be coupled to MD process. The interest of using solar powered membrane distillation (SPMD) systems for desalination is growing worldwide due to the MD attractive features. Small scale SPMD units suitable to provide water for human needs in remote areas where water and electricity infrastructures are currently lacking have been developed and tested by a number of researchers. The combination of solar energy with MD has proven technically feasible; however, the cost of produced water is relatively high compared with that produced from the commercial PV–RO process. The production of commercial, reliable, low cost and long lasting MD modules will put this process on the front edge of desalination technologies. The aim of this article is to present the main features of MD along with its basic principles. Efforts of researchers in coupling MD with solar energy and their cost estimates are reviewed as well.

Technical evaluation of stand-alone solar powered membrane distillation systems

Solar-powered membrane distillation (SP-MD) desalination systems have been proposed as promising technology in off-grid areas with strong solar radiation. However, despite the various SP-MD pilot systems constructed and tested over the past two decades, such systems have not been commercialized or implemented on a large scale yet. The objective of this study is to provide a comprehensive review and assessment of established SP-MD systems and to identify common and contrasting features among them. The study focuses mainly on SP-MD systems that had been tested under field conditions for at least several days and which are either fully or partially powered by solar energy. The systems were first reviewed in terms of their physical properties and operating conditions. The systems were then evaluated in terms of several performance indicators, such as membrane flux achieved, energy consumption, gained output ratio (GOR), performance ratio, and the energy recovery scheme applied. A numerical model was constructed and run to evaluate how a key performance indicator, GOR, can be enhanced by certain operating parameters. The results of this study are used to suggest new areas of improvement for future SP-MD projects.

Seawater desalination by an innovative solar-powered membrane distillation system: the MEDESOL project

This paper deals with the MEDESOL (Seawater Desalination by Innovative Solar-Powered Membrane Distillation System) project, partially supported by the European Commission under the Horizontal Programme “Global Change and Ecosystems (Global 4)”. Despite the advantages of solar membrane distillation (MD) systems, very few experimental systems have been developed compared with the mature technologies of solar PV-driven reverse osmosis and solar distillation. The main objective of the MEDESOL project is the development and experimental assessment of the solar multi-stage MD concept in order to develop a high-efficiency and cost-effective system for seawater desalination. EU and developing country scenarios will be analyzed. The layout involves the integration of several membrane distillation modules into a multistage MD system in order to minimize the specific energy consumption. The aim is to develop systems for a capacity range from 0.5 m3/d to 50 m3/d. Technical simplicity, long maintenance-free operation periods and high-quality fresh water output are the most important aims which will enable successful application of the systems that are based on MD. The heat source will proceed from an advanced compound parabolic solar concentrator, developed for the specific concentration ratio to achieve the specific needed range of temperatures, and the seawater heater will include the development of advanced non-fouling surface coatings to avoid scaling. Laboratory tests under defined testing conditions of all components will permit the preparation of successful field tests under real conditions, to be performed in Spain and Mexico.

Analysis of a solar-powered membrane distillation system

Nowadays, in dry and rural areas, solar-powered membrane distillation (SPMD) technology is considered a feasiblemeans for the production of pure water from brackish water. Prior to the design and construction of a SPMD pilot plant, there is a need to predict its performance theoretically by means of a computational simulation program. Unlike previous approaches followed by other investigators to develop a mathematical model that can describe the components of a SPMD pilot plant, the developed mathematical model in this study is based on the fact that the SPMD process by nature is unsteady. The performance of a proposed SPMD pilot plant is then obtained by means of a numerical solution of the model with the aid of a simulation computer program. The results reveal that the proposed SPMD pilot plant has some unique features, which differ from a similar MD process operated at steady-state conditions in a laboratory. The analysis of the system has shown that heat recovery via an external heat exchanger is not only possible, but even effective, and an economical way to intensify the SPMD process. The plant productivity can be improved by increasing the heat-exchanger capacity (KA), decreasing the flow rates of both feed and permeate or otherwise by increasing the effective surface area of the membrane. The achieved enhancements in the SPMD pilot plant productivity are directly related to an improved heat recovery rate in the heat exchanger. However, further analysis reported in this paper shows that the increase in KA and membrane area should be optimized for any planned capacity in the design of a SPMD pilot plant.