Experimental Investigation of a Pilot Solar-Assisted Permeate Gap Membrane Distillation

Article Experimental Investigation of a Pilot Solar-Assisted Permeate Gap Membrane Distillation

Mohammed M. Alquraish 1, Sami Mejbri 2, Khaled A. Abuhasel 1 and Khalifa Zhani 1,2,*

1 Department of Mechanical, College of Engineering, University of Bisha, P.O. Box 199, Bisha 61922, Saudi Arabia; [email protected] (M.M.A.); [email protected] (K.A.A.) 2 Laboratory of Electromechanical Systems (LASEM), National Engineering School of Sfax, University of Sfax, Sfax 3038, Tunisia; [email protected] * Correspondence: [email protected]

Abstract: This research deals with the process of water desalination, involving an experimental design used to study a new prototype of a solar membrane distillation plant based on the weather conditions of Kairouan City, Tunisia. In this experiment, the pilot is left autonomous with the sun as the only source of energy. The operating process of a desalination plant consists of solar energy provided by the sun using solar energy collectors, which provide energy through their photovoltaic panels for heating brackish water. Additionally, the membrane used in this study was of the spiral wound design, which allowed for a compact arrangement besides effective internal heat recovery. The system start-up was successfully carried out and experimental studies were launched on various days of August 2020. During the experiment, the average production was approximately 15.92 L/m2 ap per day while the distillate’s electoral conductivity amounted to 1865 µS/cm. Calculations revealed 3 that the speciﬁc thermal energy consumption for the system ranged between 90 and 310 kWh/m .

Citation: Alquraish, M.M.; Mejbri, S.; Keywords: distillate quality; solar desalination; PGMD; membrane distillation; solar water collectors; Abuhasel, K.A.; Zhani, K. photovoltaic solar collectors Experimental Investigation of a Pilot Solar-Assisted Permeate Gap Membrane Distillation. Membranes 2021, 11, 336. https://doi.org/ 1. Introduction 10.3390/membranes11050336 Water scarcity is a growing issue for a rising global population which is expected to surpass 8.3 billion people by 2030 [1]. In a 2013 study [2], it was estimated that approxi- Academic Editor: Chii-Dong Ho mately 700 million people were suffering from the scarcity of water and this number is expected to go up to 2.8 billion by the year 2025. On the other hand, the global demand for Received: 1 March 2021 freshwater is predicted to rise by over 50% by 2050 [1]. For this reason, seawater desalina- Accepted: 29 April 2021 Published: 30 April 2021 tion is widely regarded as a solution to the problem of dwindling freshwater resources, especially in arid and semi-arid regions. In 2000, operational desalination plants in various 3 Publisher’s Note: MDPI stays neutral parts of the world generated an estimated 7 million m /day [3] of freshwater, while today, 3 with regard to jurisdictional claims in this capacity has increased to reach 78.4 million m /day [4]. However, about 8–17% of these published maps and institutional affil- desalination plants are using thermally powered MED (multi-effect distillation) and MSF iations. (multi-stage flash) technology versus 70% that are using electrically driven reverse osmosis (RO) technology, which makes them very high capacity desalination but capital and energy intensive plants [3]. However, only 3.5% of the desalination capacity of the world is generated by small-scale plants (less than 1000 m3/day) [3], which is needed mainly in rural areas where 80% of the population has no access to fresh drinking water. Moreover, the Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. three desalination technologies mentioned above require a significant amount of chemicals This article is an open access article for smooth operation, which creates an additional cost and logistical hassle in rural areas. distributed under the terms and As such, there is rising demand for the enhancement of small-scale, chemical-free, and conditions of the Creative Commons operationally non-complex desalination technology, preferably coupled with a renewable Attribution (CC BY) license (https:// energy system that can be implemented in rural areas. On the other hand, membrane creativecommons.org/licenses/by/ distillation (MD), as a desalination method, can largely meet the above criteria since its 4.0/). scalability makes it suitable for a wide range of applications vis-à-vis the operational

Membranes 2021, 11, 336. https://doi.org/10.3390/membranes11050336 https://www.mdpi.com/journal/membranes Membranes 2021, 11, 336 2 of 14

capacity Although the distillation process itself does not rely on any chemical treatment, as it is determined by properties of the inlet feed water, some kind of pre-treatment might be necessary for a longer operational life. Besides, the easy coupling with renewable energy (notably solar thermal energy) makes MD especially suitable for stand-alone and off-grid applications [5,6].

2. Solar-Assisted Membrane Distillation Systems—State of the Art Some of the many exploration endeavors to utilize sun-based energy to supply the MD with power are presented in the accompanying passages. For example, M. Burhan et al. [7] tried the vacuum membrane distillation (VMD) arrangement framework from MEMSYS. This framework involves 4 VMD portions in an arrangement that is made out of absolute four VMD modules that are working in single and multi-impact designs. It is comprised of numerous layer outlines that are associated with a specific example to create an appropriate progression of each of the framework liquid. The outcomes indicated that energy utilization in a solitary impact setup is higher than 13.5 kW, being the energy provided to four modules simultaneously, while in a multi-impact arrangement, energy utilization is under 3.4 kW. Thus, the distillate creation in the single-impact design has an outstanding pattern and turns out to be high at a lower feed temperature. Then again, the distillate creation in the multi-impact setup demonstrated a higher energy utilization although it had an immersion point of 45 ◦C. In this context, Farzaneh Mahmoudi et al. [8] tried a lab-scale plate-and-casing permeate gap membrane distillation (PGMD) module with 0.12 m2 successful film territory. Under various working trial conditions, the feed stream rate was ((0.1–1.1) L/min), temperature input module was (TCi = 15 ◦C, TEi = 82 ◦C), penetrate motion differed from (2–12) kg/(m2·h), explicit nuclear power utilization was between (1000–2500) kWh/m3, and GOR < 1. The exploratory outcomes indicated that when the saline feed stream rate increased at the level of (0.4–1) lit/min, the new water transition increased from 3 to 11 kg/(m2·h), and similarly, the nuclear power increased by almost 20%. For their part, Wafa Suwaileha et al. [9], incorporated a manure-driven forward assimilation inexhaustible fueled film refining framework for bitter water desalination. This framework was used to deliver water for fertigation, recover the weakened draw arrangement, and concentrate consumable water. The key trial results uncovered a water saturation of about 5.7 LMH and a high dismissal of 99.55% at a temperature of 60 ◦C. Additionally, ideal explicit energy of about 0.32 kWh/m3 was accomplished at the most minimal distribution pace of 50 mL/min. Then again, with the use of a concentrated feed arrangement, the MD layer shows less fouling and irrelevant wetting. As for Atia E. Khalifa et al. [10], they tentatively contemplated and looked at the presentation of water hole layer refining (MS-WGMD) to multi-stage (MS-AGMD) film refining frameworks for various working conditions. The primary test results uncovered that the yield motion for equal stage-stream associations was higher than that of the arrangement associations. The MS-WGMD framework is discovered to be less delicate to changes in the feed temperature variable and the hole width than the MS-AGMD framework. The equal associations are less delicate to the change in both cold and hot stream rates than the arrangement of stage associations. Subsequently, the particular electric energy utilization is from 5 to 10 kWh/m3. Then again, Lan Cheng et al. [11] have tentatively examined and assessed the impacts of the feed temperature, the coolant temperature, the stream rate, the hole warmth conductivity, and the hole width on the motion and acquired yield proportion (GOR) on the air hole film refining (AGMD) and the saturated hole layer refining (PGMD) through self-created empty fiber layer modules with inner energy recuperation. The central trial results uncovered that the transition and GOR in both the AGMD and PGMD were influenced by the hole between the layer and the gathering surface. Accordingly, the improvement of the hole warmth conductivity by a metal net was not proficient to improve the motion and GOR. In the 0.5 mm hole, Membranes 2021, 11, 336 3 of 14

the motion and the GOR expanded by 7.9% and 59.82% in the PGMD contrasted with the AGMD. Besides, salt maintenance was more prominent than 99.8% in all tests. For their part, Aism et al. [12] introduced a close planetary system for a solitary family manor in Dubai. The pilot framework was intended to satisfy the need of 250 L/d. high-temperature water and 15–25 L/d of unadulterated drinking water. The framework utilized the air hole layer refining desalination cycle and level plate gatherer of the opening area of 11.85 m2. In this unique situation, the test indicated that this framework was adequate for home-grown boiling water for a solitary family manor of 4–5 people, which can deliver 16 L/d of unadulterated drinking water and 273 L/d of home-grown heated water at a normal temperature of about 50 ◦C. At this point, Guillen-Burrieza et al. [13] have tentatively considered the presentation of a hole film refining sun-powered desalination pilot for a European venture, the MEDESOL project situated in the Solar Platform of Almería (PSA), Spain. The outcomes indicated that the exhibition of the framework is influenced by the temperature of the feed and the stream pace of the liquid stream. The results demonstrated that the presentation proportion of the framework was under 1 and diminished somewhere in the range between 8 and 16% by expanding the saltiness of food from 1 to 35 g/L. It was additionally seen that three multi-stage module frameworks help limit nuclear power utilization. As for Winter et al. [14] from the Fraunhofer Institute for Solar Energy, they contemplated frameworks on a winding injury MD-modules with a layer surface region of 5–14 m2. The trial results indicated a significant impact of the feed stream and the feed water saltiness on the boundaries and execution of the twisting injury module idea. Besides, during all examinations, the distillate conductivity did not surpass dist = 3.5 S/cm, which is viewed as extremely low. In a starter exploration utilizing a two-venture measure design, it is conceivable to create a high immaculateness distillate with conductivity as low as 0.19 S/cm. In their examination, Manna et al. [15] explored another level sheet cross-stream layer module furnished with hydrophobic polyvinylidene fluoride (PVDF) microfiltration film for the expulsion of arsenic from defiled groundwater. At a feed temperature of 60 ◦C, the acquired yield proportion was discovered to be 0.9, the warm recuperation proportion 0.4, and the water transition 90 kg/(m2·h), and an arsenic convergence of 396 ppb, a pervade stream pace of 150 kg/h, and an influent stream pace of 120 kg/h was resolved. A reduction in distillate was seen with expanding arsenic content in the feed water. For their part, Raluy, R.G et al. [16] designed and introduced at the Instituto Tec- nológico de Canarias (ITC) in Playa de Pozo Izquierdo a sun powered minimal MD show plant. Results were discovered following five years of execution to be palatable. The distillate of the unit differs varies between 5–120 L/d with a conductivity scope of 20–200 µS/cm and explicit nuclear power utilization in the scope of 140–350 kWh/m3. At this point, Chang et al. [17] examined a sun-based film refining desalination framework SMDDS which uses the air hole type layer refining. The framework is made out of a chilly liquid indoor regulator, hot warm stockpiling tank, siphons, and energy recuperation unit. The outcomes indicated that in radiant days, the distillate was discovered to be 0.258 kg/d while in shady days, the distillate was discovered to be 0.142 kg/d. From past research, the hypothetical and exploratory investigations on the penetrate hole layer refining setup are extremely restricted. The point of this work is to consider and assess the exhibition of another model of sun-based desalination with a PGMD standard under various variables (working boundaries, climate conditions).

3. Material and Methods The pilot plant was introduced by the Higher Institute of Applied Science and Tech- nology and was worked under the weather conditions of Kairouan, Tunisia. The distinctive working boundaries (stream rate, water bay, and outlet temperature of every segment of the plant, sun-based radiation) and their effect on efﬁciency were examined utilizing the control and observing instruments introduced on the plant. Besides, a warm investigation Membranes 2021, 11, 336 4 of 16

Membranes 2021, 11, 336 4 of 14 the control and observing instruments introduced on the plant. Besides, a warm investi‐ gation was carried to decide the acquired yield proportion (GOR), the exhibition propor‐ tion (PR), and the specific thermal energy consumption (STEC). was carried to decide the acquired yield proportion (GOR), the exhibition proportion (PR), and3.1. Experimental the specific thermal Setup energy consumption (STEC). Figure 1 shows a photograph diagram of the side and rear views of the experimental 3.1. Experimental Setup setup, while Figure 2 illustrates the hydraulic structure of the experimental setup. Accord‐ ingly,Figure the overall1 shows system a photograph consisted diagram of three of interacting the side and circuits. rear views Firstly, of the the experimental solar circuit setup,provides while the Figure thermal2 illustrates energy required the hydraulic to heat structure the flow. of This the consists experimental of the setup. solar collector Accord- ingly,array, thethe output overall of system which consisted is directed of to three a heat interacting exchanger circuits. that transfers Firstly, the the solar solar heat circuit from providesthe solar circuit the thermal to the energy MD module required [M]. to The heat working the flow. liquid This consistsin the sun of‐ thepowered solar collectorcircuit is array,characteristic the output mineral of which water is directedwith pH to = a7.7 heat to exchangershield the thatsun‐ transfersbased gatherers the solar from heat open from‐ theness solar to the circuit pungent to the feed MD water. module The [M]. programmed The working deaerator liquid in is the utilized sun-powered on the sun circuit‐pow is‐ characteristic mineral water with pH = 7.7 to shield the sun-based gatherers from openness ered gatherers to consequently empty the air contained in the liquid during the filling and to the pungent feed water. The programmed deaerator is utilized on the sun-powered beginning stages. Furthermore, the desalination circuit comprises the MD module [M], gatherers to consequently empty the air contained in the liquid during the filling and which is a spiral‐wound design that provides an effective internal heat recovery [14], as beginning stages. Furthermore, the desalination circuit comprises the MD module [M], well as a compact arrangement. Then again, the inner warmth recuperation is the warmth which is a spiral-wound design that provides an effective internal heat recovery [14], as recuperated from the cool feed water in the condenser pipe. The construction and format well as a compact arrangement. Then again, the inner warmth recuperation is the warmth of a winding injury layer with PGMD, which appears in Figure 3, comprises three chan‐ recuperated from the cool feed water in the condenser pipe. The construction and format nels; a condenser channel (Cin and Cout), an evaporator channel (Ein and Eout), and a of a winding injury layer with PGMD, which appears in Figure3, comprises three channels; distillate channel (Dout), and 5 associations. Finally, the condenser and evaporator chan‐ a condenser channel (Cin and Cout), an evaporator channel (Ein and Eout), and a distillate nels are isolated by the hydrophobic layer. Third, the sun‐oriented photovoltaic circle cre‐ channel (Dout), and 5 associations. Finally, the condenser and evaporator channels are isolatedates the vital by the electrical hydrophobic energy layer. for the Third, activity the of sun-oriented the unit (siphons, photovoltaic PC). The circle field creates of photo the‐ vitalvoltaic electrical authorities energy consists for the of activity4 modules, of the DC unit volta (siphons,ge controllers PC). The 12/24 field VDC of photovoltaic30, and force authoritiesinverter 230 consists V/1 kW. of Then, 4 modules, two electrical DC voltage sun controllers‐oriented batteries 12/24 VDC 12 V/230 30, and AH force are inverterutilized 230to balance V/1 kW. out Then, and twocontrol electrical the force sun-oriented from the batteriesphotovoltaic 12 V/230 board. AH The are four utilized PV boards to balance are outcollected and control in equal the and force in fromarrangement the photovoltaic with a creating board. The limit four of .1 PV kW boards Specialized are collected insights in equalconcerning and in the arrangement sun‐based withgatherer a creating field and limit other of 1 kW.significant Specialized parts insights can be concerningfound in Table the sun-based1. gatherer field and other significant parts can be found in Table1.

FigureFigure 1. 1.Side Side and and rear rear views views of of the the experimental experimental setup. Membranes 2021, 11, 336 5 of 14 Membranes 2021, 11, 336 5 of 16 Membranes 2021, 11, 336 5 of 16

Figure 2. Hydraulic layout of the experimental setup. FigureFigure 2. 2.Hydraulic Hydraulic layout layout of of the the experimental experimental setup.

Figure 3. Schematic of the concept of spiral wound module (1) condenser entrance, (2) condenser exit, (3) evaporator FigureFigure 3.3. SchematicSchematic ofof thethe conceptconcept ofof spiralspiral woundwound modulemodule (1)(1) condensercondenser entrance,entrance, (2)(2) condensercondenser exit,exit, (3)(3) evaporatorevaporator entrance, (4) evaporator exit, (5) distillation exit, (6) condenser path, (7) evaporation path, (8) condenser foil, (9) distillation entrance,entrance, (4) (4) evaporator evaporator exit, exit, (5) (5) distillationdistillation exit, exit, (6)(6) condensercondenser path, path, (7)(7) evaporationevaporation path, path, (8)(8) condensercondenser foil,foil, (9)(9) distillationdistillation path, and (10) hydrophobic membrane. path,path, and and (10) (10) hydrophobic hydrophobic membrane. membrane. Table 1. Technical details of the solar collector field and other important components. Table 1. TechnicalTable 1. detailsTechnical of the details solar of collector the solar field collector and other field importantand other components.important components. Water Solar Collector Membrane Distillation Pv Monocrystalline Module Water Solar CollectorWater Solar Collector Membrane DistillationMembrane Distillation Pv Pv Monocrystalline Monocrystalline Module Module Temperature Area 2 m2 Area Area2 m2 Area 10 m2 10 m2 TemperatureTemperature range −40−40 to to 85 ◦ C°C Tube material copperArea Module-height2 m2 grossArea = 900 mm net = 72510 mm m2 Module dimensionrange 1.640−40× to992 85 mm °C range Tube thickness 0.002 m Material Polytetrafluoroethylenegross (PTFE) = 900 weight 21 Kg Rise-outer diameter 0.0127 m LengthModule 73‐ mmgross = 900 Module Impp di‐ 8.07 A Rise thickness 0.56 ×Tube10 material Pore diametercopper Module 0.1–0.4‐ µmmm net = 725 VmppModule di‐ 1.640*992 30.55 V mm Thickness of insulation 0.1 mTube material nature separationcopper height hydrophobic mm net = 725 mension Wp 1.640*992 245 W mm Weight 48 kg condenser diameterheight 20 mm mm mension Angle 45◦ Evaporator diameter 20 mm mm 2 Polytetrafluo‐ Loss coefficient 4.8 W/m Tubek thick‐distillate diameter 20 mm Polytetrafluo‐ Tube thick‐ 0.002 m Material roethylene weight 21 Kg ness 0.002 m Material roethylene weight 21 Kg ness (PTFE) (PTFE)

Membranes 2021, 11, 336 6 of 14

3.2. Instrumentation The pilot was outﬁtted with the fundamental instrumentation for the estimation and control of the different working boundaries and climate conditions. A pyranometer type LP LYPRA 03AC was introduced on a level plane nearby the sun-based authority to gauge the all-out sun-based radiation. Thermocouple type J was introduced to gauge the power source and the channel water temperatures in every unit of the parts and surrounding temperature. At that point, the thermocouple, which gauges the surrounding temperature, is kept in a sanctuary to shield the sensor from direct daylight. Additionally, all the thermocouples are associated with an information securing framework (type Agilent 34970A) to screen and record the obtained signals. Moreover, the Agilent 34970A is associated with the USB port of the PC utilizing a USB link type AB to record varieties in bay and outlet water temperatures during the working time frame. The deﬁnite specialized information of the sensors and tests utilized in the exploratory arrangement are shown in Table2.

Table 2. Technical speciﬁcation of sensors and probes used in the experimental set up.

Component Type Description Value Thermocouple Type J Temperature sensors −50 ◦C–400 ◦C Pyranometer LP LYPRA 03AC Measuring Range 0–2000 W/m2 Pump Shurflo LS2255 Refilling Open flow 13.6 L/mn Pump Shurflo LS2255 Feed Open flow 13.6 L/mn ◦ Feed volume flow 60/185(2/96) H2O with 20 C– iden Nr: 15002 PLC Agilent BenchLink Data Logger 3 Agilent 34970a – Conductivity Meter CD-4307SD Measuring cd, salt 0 to 200 ms, 0 to 12% salt (% weight)

4. Experimental Results and Discussion The exploratory investigation of the unit was examined during the sunshine hours on various long stretches of August 2020, under the variable sun-based radiation. The trial began at 7:00 am and all boundaries were estimated and recorded every moment until 17:00. Distinctive feed stream rates (200, 300, 400, 500, 600 L/h) were utilized to report the impact of the feed stream rate on creation. Figure4 shows the everyday varieties of the inlet and outlet water temperature with sun-powered radiation for different long stretches of August. The two days, 8–9 August 2020, were described as a bright day, conversely, 6 August 2020 was viewed as an overcast day. It was recognized that the power source and delta liquid temperature followed patterns similar to the sun-based radiation. It was obvious from the ﬁgures underneath that the most noteworthy estimation of sun-based radiation was about 951.37 W/m2, which happened around early afternoon on 8 August 2020, while the most elevated encompassing temperature was reached at 13 h 30 m on 9 August 2020 at about 46.13 ◦C. We noticed that the channel and the power source water temperature of the sun-based authorities followed the conduct of the sun-based radiation. Then again, the most extreme estimations of water outlet enrolled temperatures were 89.86 ◦C in the late morning. These outcomes demonstrated that the expansion of the warm presentation for the framework was larger than that of the warm exhibition of the sun-oriented authority. The fact is that the sun-oriented authority liquid temperature greatly affects the warm exhibition of the sunlight-based gatherer. Table3 gives data about the normal qualities and the most extreme day-by-day sun-powered radiation, surrounding temperature, outlet water temperature of the sunlight- based authority, delta water temperature evaporator divert notwithstanding the distillate acquired during the activity. At that point, the most extreme creation of 159.20 kg/day was recorded on 9 August at an evaporator delta temperature of 71.91 ◦C. Membranes 2021, 11, 336 7 of 16

2020, while the most elevated encompassing temperature was reached at 13 h 30 m on 9 August 2020 at about 46.13 °C. We noticed that the channel and the power source water

Membranes 2021, 11, 336 7 of 14

80 Tamb I Tamb I August 06,2020 900 75 Tcsin 70 Tcso

800 )

Tcin 2 Tcin 2 65 Tcout Tein 700 60 Tein Teout 55 癈 55 Tdist 600 50 500 45 40 400 Solar(W/m radiation 35 (W/m radiation Solar Temperature Temperature Temperatur e 300 30 25 200 20 100 15 10 0 0 50 100 150 200 250 300 350 400 450 500 550 600 Time (min) (a)

80 1000 Tamb I August 08,2020 75 August 08,2020 Tcsin 900 70 Tcso ) ) 2 Tcin 2 65 800 65 Tcout 60 Tein 60 700 Teout 55 癈 55 Tdist 600 50 45 500 40 400 Solar radiation (W/m 35 Solar radiation (W/m Temperature Temperat ure 300 30 300

25 200 20 100 15 10 0 0 50 100 150 200 250 300 350 400 450 500 550 600 Time (min) (b)

80 1000 T amb I August 09,2020 75 Tcsin Tcsin 900 Tcso

70 )

70 ) 2 Tcin 2 800 65 Tco Tein 60 700 Teo 700 55 癈 Tdis 600 50 45 500 40 400 Solar radiation (W/m 35 Solar radiation (W/m Temperature Temperature Temperature 300 30 300 25 25 200 20 100 15 10 0 0 50 100 150 200 250 300 350 400 450 500 550 600 Time (min) (C)

Figure 4. Daily variation inlet/outlet water temperature and solar radiation for different days in August: (a) 6 August 2020, (b) 8 August 2020, (c) 9 August 2020. Membranes 2021, 11, 336 8 of 14

Table 3. Results of some measures of the average values and daily maximum for various days.

Parameter Unit 2 August 2020 3 August 2020 6 August 2020 8 August 2020 9 August 2020 Avg. Solar Radiation W/m2 601.3 637.62 584.61 682.22 677.56 Max. solar radiation W/m2 859.6 896.7235 939.98 951.37 978.27 mfeed kg/h 200 300 400 500 600 distillat kg/d 46.60 73.40 101.80 142.60 159.20 ◦ Avg. Tamb C 40.908 42.23 38.39 39.87 42.61 ◦ Max. Tamb C 44.773 47.99 40.64 41.47 46.13 ◦ Avg. Tsco C 59.53 65.44 54.41 58.13 57.37 ◦ Max. Tsco C 88.21 89.86 66.99 69.79 71.58 ◦ Avg. Tein C 52.73 57.25 53.51 57.39 59.71 ◦ Max. Tein C 76.08 71.884 66.88 70.211 71.91

4.1. The Effect of Global Radiation on the Production Unit Figure5 shows day-by-day water profitability as an element of sun-oriented radiation. These outcomes show that there is an immediate impact of sun-based radiation on the measure of the delivered distillate. This shows the creation of the plant increments with the increment of sunlight-based radiation and the other way around for 8 h of persistent Membranes 2021, 11, 336 9 of 16 activity. The specific purpose behind the observed impact of sunlight-based radiation on new water creation was that the temperature of the feedwater leaving the level plate gatherers increased with the increment in the force of sun-powered radiation. Subsequently, layer,as which the feed prompted water temperature an increment at the in dissipationthe new water channel creation expanded of the becauseframework. of the Moreo warming‐ ver,of with the a sun-based sun‐oriented authority, gatherer the region temperature of 6 m2 and contrasts no warmth across stockpiling the expanded tank, layer, the eve which‐ rydayprompted creation an came increment to about in 15.92 the new L/m water2 assortment creation territory of the framework.when the sun Moreover,‐based radia with‐ a tionsun-oriented arrived at its gatherer most extreme region of estimation 6 m2 and no of warmth 978.27 W/m stockpiling2. The tank,measure the everydayof new water creation accomplishedcame to about was 15.92 a promising L/m2 assortment incentive territory for an underlying when the sun-based test of the radiation framework. arrived The at its newmost water extreme creation estimation of the ebb of and 978.27 flow W/m model2. The was measure additionally of new improved water accomplished by incorporat was‐ a ing promisinga control calculation incentive dependent for an underlying on climate test boundaries of the framework. and a sun The‐based new warmth water creation stock‐ of pilingthe tank ebb andinto flowthe framework model was to additionally broaden the improved activity past by incorporating nightfall. a control calculation dependent on climate boundaries and a sun-based warmth stockpiling tank into the framework to broaden the activity past nightfall.

16 15 14 13 12

ap area) 11 2 10 9 8

7 6 5 4 3 2 1 Daily production (l/m 0 100 200 300 400 500 600 700 solar irradiation W/m2

Figure 5. Regular output of fresh water versus solar radiation. Figure4.2. 5. Impact Regular of output the Feed of Streamfresh water Rate versus on Fresh solar Water radiation. Production 4.2. ImpactFigure of the6 showsFeed Stream the impact Rate on of Fresh the feed Water water Production volume stream on the new water creation of the model. We conducted two investigations on various days in August 2020 in which Figure 6 shows the impact of the feed water volume stream on the new water creation we changed the feed water volume stream from 200 L/h to 600 L/h for ﬁve distinct days. of theThe model. primary We perception conducted that two we investigations can make from on thevarious acquired days outcomesin August is 2020 that in the which creation we ofchanged the distillate the feed stream water expands volume withstream the from expansion 200 L/h of to the 600 feed L/h waterfor five volume distinct stream days. for Thethe primary two tests. perception In fact, that by we raising can make the feed from stream the acquired rate from outcomes 200 to 600is that L/h, the the creation distillate of the distillate stream expands with the expansion of the feed water volume stream for the two tests. In fact, by raising the feed stream rate from 200 to 600 L/h, the distillate transition increments by 43.33% and 62.63% for analyses 1 and 2, separately. This finding can be attributed to the fact that with the increment in the feed stream rate, the choppiness in the stream channel increments. This builds the quantity of Reynolds, which improves the warmth and mass exchange coefficients in the stream channels and diminishes the impact of temperature polarization at different sides of the layer zone, enhancing the main thrust temperature contrast, and finally, leading to a higher distillate motion. This trial finding was in concurrence with that of Zaragoza et al. [18], who confirmed that the great‐ est distillate transition was obtained at the most extreme feed stream rate because of a higher disturbance at the higher feed stream rate and lower polarization impact of tem‐ perature. The subsequent perception was that the distillate motion acquired during the subsequent test was more noteworthy than the first because of the sun‐powered radiation impact. Figure 6 also shows the contrast between the distillate motion estimations of the two tests increments with the increment in the feed stream rate. This may demonstrate that the distillate motion was more sensitive to the stream rate than to the power of the sun‐based radiation.

Membranes 2021, 11, 336 9 of 14

transition increments by 43.33% and 62.63% for analyses 1 and 2, separately. This finding can be attributed to the fact that with the increment in the feed stream rate, the choppiness in the stream channel increments. This builds the quantity of Reynolds, which improves the warmth and mass exchange coefficients in the stream channels and diminishes the impact of temperature polarization at different sides of the layer zone, enhancing the main thrust temperature contrast, and finally, leading to a higher distillate motion. This trial finding was in concurrence with that of Zaragoza et al. [18], who confirmed that the greatest distillate transition was obtained at the most extreme feed stream rate because of a higher disturbance at the higher feed stream rate and lower polarization impact of temperature. The subsequent perception was that the distillate motion acquired during the Membranes 2021, 11, 336 subsequent test was more noteworthy than the first because of the sun-powered radiation 10 of 16

impact. Figure6 also shows the contrast between the distillate motion estimations of the two tests increments with the increment in the feed stream rate. This may demonstrate that the distillate motion was more sensitive to the stream rate than to the power of the sun-based radiation.

150 Experiment 1 140 Experiment 2 130 120 110 100 90 80

70 60 50 40

Distillate flux (kg/d) 30 20 10 0 100 200 300 400 500 600 Feed flow rate (L/h)

Figure 6. The effect of the feed flow rate on the prototype’s output of freshwater. Figure 6. The effect of the feed flow rate on the prototype’s output of freshwater. At the point when bitter water vanishes and the fume goes through the pore of the layer, the distillate is framed in the distillate direct and afterward gathers in the distillate At the point when bitter water vanishes and the fume goes through the pore of the tank [S.003], while the rest of the saline solution goes back to the feed tank [S.002]. In fact, layer,along the distillate these lines, is a portion framed of in the the feed distillate is retrieved direct as distillate. and afterward Figure7 shows gathers the distillate in the distillate tank recuperation[S.003], while as a the component rest of ofthe sun-powered saline solution radiation. goes Then back again, to the the feed rate recuperation tank [S.002]. In fact, alongis these characterized lines, a byportion the proportion of the feed of distillate is retrieved stream as rate distillate. to be considered. Figure 7 This shows implies the distillate recuperationthat the recuperation as a component rate increments of sun‐ withpowered the increment radiation. of the Then sunlight-based again, the irradiance, rate recuperation which was not yet over 3%. This rate recuperation was in concurrence with the after-effects is characterizedof past examinations by the utilizingproportion the winding of distillate injury stream air hole filmrate refining to be considered. module [19]. AnThis implies that theexperimental recuperation work developed rate increments by Banat etwith al. [ 20the] on increment a similar membrane of the sunlight distillation‐based system irradiance, whichusing was a directnot yet contact over module, 3%. This showed rate that recuperation the percentage was recovery in concurrence increased considerably with the after‐ef‐ fects withof past increasing examinations the global utilizing irradiation, the but winding it was no moreinjury than air 4%. hole One film can concluderefining that module [19]. direct contact membrane distillation (DCMD) has a greater recovery ratio than PGMD. An experimental work developed by Banat et al. [20] on a similar membrane distillation system using a direct contact module, showed that the percentage recovery increased con‐ siderably with increasing the global irradiation, but it was no more than 4%. One can con‐ clude that direct contact membrane distillation (DCMD) has a greater recovery ratio than PGMD.

3.0

2.5

2.0

1.5

1.0 % Recovery

0.5

0.0 12345678 Sum of daily Solar radiation (kWh/m2)

Membranes 2021, 11, 336 10 of 16

150 Experiment 1 140 Experiment 2 130 120 110 100 90 80

70 60 50 40

Distillate flux (kg/d) 30 20 10 0 100 200 300 400 500 600 Feed flow rate (L/h)

Figure 6. The effect of the feed flow rate on the prototype’s output of freshwater.

At the point when bitter water vanishes and the fume goes through the pore of the layer, the distillate is framed in the distillate direct and afterward gathers in the distillate tank [S.003], while the rest of the saline solution goes back to the feed tank [S.002]. In fact, along these lines, a portion of the feed is retrieved as distillate. Figure 7 shows the distillate recuperation as a component of sun‐powered radiation. Then again, the rate recuperation is characterized by the proportion of distillate stream rate to be considered. This implies that the recuperation rate increments with the increment of the sunlight‐based irradiance, which was not yet over 3%. This rate recuperation was in concurrence with the after‐ef‐ fects of past examinations utilizing the winding injury air hole film refining module [19]. An experimental work developed by Banat et al. [20] on a similar membrane distillation system using a direct contact module, showed that the percentage recovery increased con‐ siderably with increasing the global irradiation, but it was no more than 4%. One can con‐ clude that direct contact membrane distillation (DCMD) has a greater recovery ratio than Membranes 2021, 11, 336 10 of 14 PGMD.

3.0

2.5

2.0

1.5

1.0 % Recovery

0.5

0.0 Membranes 2021, 11, 336 12345678 11 of 16

Sum of daily Solar radiation (kWh/m2)

FigureFigure 7. Distillate 7. Distillate recovery recovery as a function as a of function solar radiation. of solar radiation. 5. Execution Pointers 5. Execution Pointers

ExecutionExecution markers markers in warm in refining warm measures reﬁning are measures all around are characterized, all around for characterized, the for the mostmost part, part,unaltered unaltered across refining across advancements reﬁning advancements and omnipresent and in omnipresent test works, among in test works, among whichwhich the accompanying the accompanying were chosen were for chosen this examination: for this examination:

5.1. 5.1.Explicit Explicit Thermal Thermal Power Utilization Power Utilization or STEC or STEC The warmthThe warmth energy energyis needed is to needed deliver a to unit deliver volume a unit of penetrate. volume This of penetrate.presentation This presentation pointer is basic among all warm refining advancements and perhaps the most broadly pointer is basic among all warm refining advancements and perhaps the most broadly utilized benchmark of warm execution. utilizedThe particular benchmark nuclear power of warm utilization execution. is considered as the proportion of the energy the warmthThe exchanger particular supplies nuclear to the power amount utilization of the distillate is considered produced. as the proportion of the energy the warmth exchanger supplies to theQ amount of the distillate produced. STEC  HX m (1) p QHX STEC = . (1) The STEC can be extended and modified by the accompanyingmp basic thermodynamic condition The STEC can be extended and modified by the accompanying basic thermody- mC f pf() T eout T ein namic condition. STEC  . (2) mmpf Cp f (Teout − Tein) STEC = . (2) From Figure 8, it can be observed that the particular warmthmp energy utilization de‐ 3 termined Fromfor this Figure framework8, it is can in the be scope observed of 90 to that 310 kWh/m the particular. Nonetheless, warmth this out energy‐ utilization come is frail when contrasted with other desalination measures, for example, sunlight‐ determined for this framework is in the scope of 90 to 310 kWh/m3. Nonetheless, this based still (640 kWh/m3) [20]. Hence, the MD cycle could be vigorously intensified with otheroutcome desalination is frail advances. when contrasted with other desalination measures, for example, sunlight- based still (640 kWh/m3)[20]. Hence, the MD cycle could be vigorously intensified with other desalination advances.

400

350

300

3 250

200

150

STEC kWh/m 100

0 2345678 2 Sum of daily solar irradiation (kWh/m ) Figure 8. Inﬂuence on the STEC of regular daily radiation. Figure 8. Influence on the STEC of regular daily radiation.

5.2. Gained Output Ratio or GOR GOR is a worldwide proportion of the energy proficiency of the framework. A higher acquired yield proportion relates to a lower energy utilization for every unit of the deliv‐ ered distillate. GOR is a more itemized pointer of energy proficiency measure. Then, being very similar to the STEC, the GOR can be considered as the proportion of the warmth

Membranes 2021, 11, 336 12 of 17

warmth needed to disintegrate the saturate and the real provided heat. Moreover, it is generally utilized as an exhibition marker, and hence, can be presented as follows: mH Δ GOR = pV − (3) mC f pf() T eout T ein As can be seen in Figure 9, contingent upon the day-by-day sun-oriented radiation, the GOR after-effects of this framework are in the scope of 0.3 and 1.4. Banat et al. [20] calculated the GOR of a DCMD module at mid-noon of each day and found that the GOR varied from one day to another depending on the sum of daily irradiation and was in the range of 0.3–0.9. Thus, the current system presents a greater GOR. Membranes 2021, 11, 336 11 of 14

1,75 5.2. Gained Output Ratio or GOR GOR1,50 is a worldwide proportion of the energy proﬁciency of the framework. A higher acquired yield proportion relates to a lower energy utilization for every unit of the delivered distillate.1,25 GOR is a more itemized pointer of energy proﬁciency measure. Then, being very similar to the STEC, the GOR can be considered as the proportion of the warmth needed to 1,00 disintegrate the saturate and the real provided heat. Moreover, it is generally utilized as an

exhibition0,75 marker, and hence, can be presented as follows: GOR . mp∆HV 0,50 GOR = . (3) m f Cp f (Teout − Tein) 0,25 As can be seen in Figure9, contingent upon the day-by-day sun-oriented radiation, the GOR0,00 after-effects of this framework are in the scope of 0.3 and 1.4. Banat et al. [20] calculated the12345678 GOR of a DCMD module at mid-noon of each day and found that the GOR Sum of daily solar irradiation (kWh/m2) varied from one day to another depending on the sum of daily irradiation and was in the range of 0.3–0.9. Thus, the current system presents a greater GOR.

FigureFigure 9. 9. TheThe effect effect of of regular regular radiatio radiationn on the output ratio gained. 6. Distillate Quality 6. Distillate Quality In light of a few led tests, numerous scientists indicated that the dismissal pace of MD is In light of a few led tests, numerous scientists indicated that the dismissal pace of assumed to be high. In this way, the estimations of the distillate conductivity are performed MD is assumed to be high. In this way, the estimations of the distillate conductivity are to check the usefulness of the twisting loop module and assess the nature of the distillate. performed to check the usefulness of the twisting loop module and assess the nature of Moreover, since the pressing factor level on the evaporator and condenser channels is more the distillate. Moreover, since the pressing factor level on the evaporator and condenser noteworthy than that of the distillate channels, it means that any blemish or deformity would bring about an expansion of conductivity, for example, the expansion of the salt substance of the distillate. The feed water with a conductivity of k feed = 18,480 µS/cm is roughly 11.75 g/L and utilized with a volume stream pace of 400 kg/h. The consequences of the distillate water conductivity acquired over the long haul are presented in Figure 10. Over a few minutes, the deliberate conductivity is viewed as high and enlisted at about 12,750 µS/cm, which is around 7.82 g/L, and drops afterward. After 2 h of activity, the conductivity reached an estimation of kdist = 4180 µS/cm, which was roughly 2.4 g/L, at that point then, after 5 h of activity, the worth gets steady at about kdist = 1865 µS/cm, which was around 1.044 g/L of saltiness. MembranesMembranes 20212021,, 1111,, 336336 1213 ofof 1416

Figure 10. Variation of conductivity and salinity.salinity.

7. EconomicOver a few Study minutes, the deliberate conductivity is viewed as high and enlisted at aboutThe 12,750 determination μS/cm, which of the is costaround of freshwater 7.82 g/L, and production drops afterward. and the payback After 2 periodh of activity, of the PGMDthe conductivity process is reached based on an a estimation variety of parameters.of kdist = 4180 In μ general,S/cm, which the investigation was roughly method2.4 g/L, dependsat that point on the then, calculation after 5 h ofof capital activity, and the operating worth gets costs. steady Therefore, at about the kdist total = 1865 once-a-year μS/cm, costwhich of was desalination, around 1.044Ctot, isg/L determined of saltiness. as the sum of the annual amortization or fixed cost, Cfixed, and the annual maintenance and operating cost, Co&m: 7. Economic Study C = aC + C The determination of the cost totof freshwaterf ixed productiono&m and the payback period(4) of the PGMD process is based on a variety of parameters. In general, the investigation The payments over time (amortization) factor, a, is a function of the year or lifetime of themethod unit, dependsn, and the on annual the calculation interest rate of (%), capitali: and operating costs. Therefore, the total once‐a‐year cost of desalination, Ctot, is determined as the sum of the annual amortization n or fixed cost, Cfixed, and the annual maintenancei(1 + andi) operating cost, Co&m: a = (5) (1 + i)n − 1 CaCCtot fixed o& m (4) The unit cost of produced water, WPC, is the ratio of the total annual cost to the quantityThe producedpayments annuallyover time by (amortization) the prototype: factor, a, is a function of the year or lifetime of the unit, n, and the annual interest rate (%), i: Ctot WPC = . n (6) iifm1 365 a  dis n (5) Since the solar membrane distillation11 planti is not in quotidian operation, a plant availability factor (f ) was introduced to adjust the annual expenditure. The cost analysis The unit cost of produced water, WPC, is the ratio of the total annual cost to the quan‐ was based on a plant availability factor of 90%, a unit life of 20 years, and an interest rate oftity 5%. produced The land annually was offered by the by prototype: the University of Kairouan, Tunisia. Tables4 and5 show, respectively, the cost of each purchased component constituting the experimental prototype Ctot and a summary of the results of theWPC cost evaluation of the experimental prototype. (6) fm dis 365 TableSince 4. Investment the solar cost membrane of each component distillation constituting plant is the not experimental in quotidian prototype. operation, a plant availabilityPrototype factor Components (f) was introduced to Quantityadjust the annual Cost expenditure. (€) The Total cost Cost analysis (€) was basedPhotovoltaic on a plant module availability 245 W factor of 90%, 4 a unit life of 188.5 20 years, and an interest 754 rate of 5%. TheThermal land solar was collector offered 2 m2 by the University3 of Kairouan, 214.6 Tunisia. Table 4 and 643.8 Table 5 Compact distillation module (PGMD, Pumps, 1 11,000 11,000 show,filters, respectively, feed tank, and heatthe exchanger) cost of each purchased component constituting the experimental Piping/Connection accessory 1 681.5 681.5 prototype andCirculation a summary pump of the results of 1the cost evaluation 101.5 of the experimental 101.5 proto‐ type. DC pumping system 1 1044 1044 DC/AC protection box 1 275.5 275.5 Wiring and cable routing 1 217.5 217.5 Battery/charge regulator/Inverter 1 788.8 788.8 Structure 1 174 174

Membranes 2021, 11, 336 13 of 14

Table 5. Summary of the cost evaluation results of the experimental prototype.

Capital cost 15,680.6 € −1 Operating and maintenance costs (Co&m) 250,886 € year Lifetime (n) 20 year Interest rate (i) 5% Amortization factor (a) 0.080 year−1 −1 Fixed charges (Cﬁxed) 125,444 € year Total unit cost 150,533 € year−1 Unit availability (f ) 90% Unit capacity 0.148 m3 d−1 Water production cost (WPC) 30.96 € m−3 Net earning 30.95 Payback period (Pb) 506.60 d

8. Conclusions The trial investigation of the pilot solar-powered saturate hole membrane distillation was observed for various days in August 2020 under the real climate of Kairouan, Tunisia. The obtained results show that the sun-oriented radiation and feed water decidedly inﬂu- ence the pervade creation of the MD module where the everyday creation reaches about 15.92 L/m2 ap with an estimated electrical conductivity of the distillate of 1865 µS/cm and 1.044 g/L saltiness. The particular nuclear power utilization determined for this framework goes from 90 to 310 kWh/m3. The GOR of the layer module shifted starting with one day, then onto the next, relying upon the day-by-day sunlight-based radiation. The GOR after-effects of this framework were in the scope of 0.3–1.4.

Author Contributions: Conceptualization, K.Z. and M.M.A.; methodology, S.M.; software, K.A.A.; investigation, M.M.A. and S.M.; resources, S.M.; data curation, S.M.; writing—original draft prepara- tion, S.M.; writing—review and editing, M.M.A. and S.M.; visualization, K.A.A.; supervision, K.Z.; project administration, M.M.A.; funding acquisition, M.M.A. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the University of Bisha, grant number UB-Promising-3-1442, and the APC was funded by UB-Promising-3-1442. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable. Acknowledgments: The authors extend their appreciation to the Deanship of Scientific Research, University of Bisha, Saudi Arabia for funding this research work through the Promising Initiative Project under Grant Number (UB-Promising-3-1442). Thanks also go to Fraunhofer Institute for Solar Energy Systems, ISE, for their collaboration. Conflicts of Interest: The authors declare no conflict of interest.

Nomenclature

I sunlight based radiation (W/m2) ◦ Tamb surrounding temperature ( C) ◦ Tscin channel water temperature of the water sunlight based authority ( C) ◦ Tsco outlet water temperature of the water sunlight based gatherer ( C) ◦ Tein entrance water temperature of the channel of the evaporator ( C) ◦ Teout outlet water temperature of the channel of the evaporator ( C) ◦ Tcin entrance water temperature of the condenser channel ( C) Membranes 2021, 11, 336 14 of 14

◦ Tcout outlet water temperature of the condenser channel ( C) ◦ Tdist water temperature of the distillate ( C) QHX complete energy input needed for the refining cycle [kWh] mP mass stream pace of pervade creation [kg/h] mF mass stream pace of the feed water [kg/h] ∆Hv water idle warmth of vaporization in [kj/kg] 2 Asolar absolute opening zone of the sun based authority field [m ] msolar mass stream rate in the sunlight based gatherer field [kg/s] ◦ CPF isobaric explicit warmth limit of the feed water [kJ/ (kg C)]

References 1. International Renewable Energy Agency. Renewable Energy in the Water, Energy & Food Nexus; IRENA: Abu Dhabi, United Arab Emirates, 2015. 2. Hameeteman, E. Future Water. In Security: Facts, Figures, and Predictions; Global Water Institute: Brussels, Belgium, 2013. 3. Winter, D. Membrane Distillation: A Thermodynamic, Technological and Economic Analysis; Deutsche Natioanlbibliothek: Aachen, Germany, 2015. 4. Global Water Intelligence. Desalination Industry Enjoys Growth Spurt as Scarcity Starts to Bite. Available online: https: //www.globalwaterintel.com/desalination-industry-joys-growthspurt-scarcity-starts-bite.Html (accessed on 13 May 2018). 5. Koschikowski, J.; Wieghaus, M.; Rommel, M.; Ortin, V.S.; Suarez, B.P.; Betancort Rodríguez, J.R. Experimental investigations on solar driven stand-alone membrane distillation systems for remote areas. Desalination 2009, 248, 125–131. [CrossRef] 6. Koschikowski, J.; Wieghaus, M.; Rommel, M. Solar thermal driven desalination plants based on membrane distillation. Water Sci. Technol. Water Supply 2003, 3, 49–55. [CrossRef] 7. Burhan, M.; Shahzad, M.W.; Ybyraiymkul, D.; Oh, S.J.; Ghaffour, N.; Ng, K.C. Performance investigation of MEMSYS vacuum membrane distillation system in single effect and multi-effect mode. Sustain. Energy Technol. Assess. 2019, 34, 9–15. [CrossRef] 8. Mahmoudi, F.; Siddiqui, H.; Pishbin, M.; Goodarzi, G.; Dehghani, S.; Date, A.; Akbarzadeh, A. Sustainable Seawater Desalination by Permeate Gap Membrane Distillation Technology. Energy Procedia 2017, 110, 346–351. [CrossRef] 9. Suwaileh, W.; Johnson, D.; Jones, D.; Hilal, N. An integrated fertilizer driven forward osmosis- renewables powered membrane distillation system for brackish water desalination: A combined experimental and theoretical approach. Desalination 2019, 471, 114126. [CrossRef] 10. Khalifa, A.E.; Alawad, S.M. Air gap and water gap multistage membrane distillation for water desalination. Desalination 2018, 437, 175–183. [CrossRef] 11. Cheng, L.; Zhao, Y.; Li, P.; Li, W.; Wang, F. Comparative study of air gap and permeate gap membrane distillation using internal heat recovery hollow ﬁber membrane module. Desalination 2018, 426, 42–49. [CrossRef] 12. Asim, M.; Uday Kumar, N.T.; Martin, A.R. Feasibility analysis of solar combi-system for simultaneous production of pure drinking water via membrane distillation and domestic hot water for single-family villa: Pilot plant setup in Dubai. Desalination Water Treat. 2015, 57, 21674–21684. [CrossRef] 13. Guillén-Burrieza, E.; Blanco, J.; Zaragoza, G.; Alarcón, D.-C.; Palenzuela, P.; Ibarra, M.; Gernjak, W. Experimental analysis of an air gap membrane distillation solar desalination pilot system. J. Membr. Sci. 2011, 379, 386–396. [CrossRef] 14. Winter, D.; Koschikowski, J.; Wieghaus, M. Desalination using membrane distillation: Experimental studies on full scale spiral wound modules. J. Membr. Sci. 2011, 375, 104–112. [CrossRef] 15. Manna, A.K.; Sen, M.; Martin, A.R.; Pal, P. Removal of arsenic from contaminated groundwater by solar-driven membrane distillation. Environ. Pollut. 2010, 158, 805–811. [CrossRef] 16. Raluy, R.G.; Schwantes, R.; Subiela, V.J.; Peñate, B.; Melián, G.; Betancort, J.R. Operational experience of a solar membrane distillation demonstration plant in Pozo Izquierdo-Gran Canaria Island (Spain). Desalination 2012, 290, 1–13. [CrossRef] 17. Chang, H.; Lyu, S.-G.; Tsai, C.-M.; Chen, Y.-H.; Cheng, T.-W.; Chou, Y.-H. Experimental and simulation study of a solar thermal driven membrane distillation desalination process. Desalination 2012, 286, 400–411. [CrossRef] 18. Zaragoza, G.; Ruiz-Aguirre, A.; Guillén-Burrieza, E. Efﬁciency in the use of solar thermal energy of small membrane desalination systems for decentralized water production. Appl. Energy 2014, 130, 491–499. [CrossRef] 19. Banat, F.; Jwaied, N.; Rommel, M.; Koschikowski, J.; Wieghaus, M. Desalination by a compact SMADES autonomous solar- powered membrane distillation unit. Desalination 2007, 217, 29–37. [CrossRef] 20. Thomas, K. Overview of Village Scale. Renewable Energy Powered Desalination 1997, NREL/TP-440 22083, UC Category: 1210 DE 97000240; National Renewable Energy Laboratory: Golden, CO, USA, 1997.