Experimental Evaluation of Novel Hybrid Multi Effect Distillation Membrane Distillation (MED -MD) driven by Solar Energy

Transcription

1 Experimental Evaluation of Novel Hybrid Multi Effect Distillation Membrane Distillation (MED -MD) driven by Solar Energy Abdelnasser Mabrouk 1, Yasser Elhenawy 2, Gamal Mostafa 2, M. Shatat 2, Mohamed El-Ghandour 2 1 Qatar Environment & Energy Research Institute, Hamad Bin Khalifa University, Qatar, aaboukhlewa@qf.org.qa 2 Faculty of Engineering, Port Said University Abstract In this work, experimental evaluation of a novel hybrid Multi Effect Distillation Membrane Distillation (MED-MD) driven by solar collector is presented. The new configuration solves some technical challenges of existing thermal MED desalination such as recovery ratio and wetting rate. The minimum wetting rate of the thin film horizontal evaporation MED is recommended to improve the thermal efficiency of the evaporator. However, on the other hand, the minimum wetting rate creates restriction on the recovery ratio and conversion factor of the evaporator in order to avoid dry patch zone with its consequences of scale deposits and drop in the evaporator thermal efficiency. In the existing design of the MED evaporator, the brine collected in the bottom is directed to the next effect through orifice to let another small portion of brine converted to vapor by flash vapor (only 1-2 %). Integrating MD to the downstream makes use of maximum conversion factor of it through vapor pressure difference rather than flashing process. Since the vapor permeate depends on the vapor pressure difference which higher than flashing process. The novel configuration MED-MD increases the overall recovery ratio. This is because the cooling reject of the down condenser of MED is used as cooling to the membrane distillation to get new amount of distillate for the same amount seawater feed to MED. Due to increase of the overall water production, the electrical energy and thermal energy consumption consequently would be decreased. Solar energy is used as heating source to provide thermal energy required to MED system. In order to maximize the efficiency of the solar energy system, sensible heat of the circulated fluid (pure water) is circulated in closed loop between the solar collector and tubes of the first effect of MED evaporator. This improves conversion process by excluding vapor generating unit with its complexity control system. The hybrid MED-MD system has been successfully demonstrated under different design and operation parameters. The results is compared to the simulation results and showed agreement. Keywords: Desalination, Solar, MED, membrane distillation RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 1

2 1. Introduction Solar desalination is a suitable solution to remote regions where fresh water source is abundant. Seawater desalination systems driven by renewable energies are get interesting focus nowadays as a green strategy based technology. Most of the studies have been focused on solar-sourced Multi-Effect Distillation (MED) practiced systems available in the literature. Several solar assisted desalination plants have been designed and implemented using the MED process [1 2]. A seawater solar desalination plant, assisted by evacuated tube collectors was designed for a maximum capacity of 120 m 3 /day with multi-effect stack (MES) distillation concept having 18 effects and, located at Abu Dhabi [3]. The system utilized the horizontal tube, thin-film and had an expected yearly average distillate water capacity of 85 m 3 /day with a design salinity of 55,000 ppm. A heat accumulator of the thermally stratified type having a total capacity of 300 m 3 was designed to maintain thermal energy to the system during 24 h/day for continuous operation. The thermal energy required by the MES evaporator was provided by a bank of evacuated glass tube collectors with an effective area of 1862 m 2 by only solar energy. The annual average daily solar insolation on horizontal surface was measured as 5000 kcal/m 2 day and the yearly average efficiency of the collector field obtained as 50% during the operation. Specific heat consumption of the plant was 43.8 kcal/kg with a performance ratio of The electrical energy required by the pumps was supplied by the main grid [3]. The MED plant of Plata forma Solar de Almeria was installed in 1988 with a design capacity of 72m 3 day [4]. The desalination system was composed of 14 effects with sprayed horizontal tube bundles for seawater evaporation limiting to 70 C to prevent from scale formation, a single-axis tracking parabolictrough collector field with a total aperture area of 2672 m 2 and a single 115 m 3 thermocline thermal storage oil tank. The daily thermal energy delivered by the collector field was about 6.5 MWh, while the daily thermal energy requirement of the desalination plant was less than 5 MWh for 24-hour daily operation. Specific electricity consumption of 3.3 up to 5kWh/m 3 of distillate and the performance ratio of the plant were in the range of when the plant was operated with low-pressure steam at 0.35 bar [4]. Designed and manufactured an evaporative multi-step distiller with a 3 m 3 /day seawater desalination capacity using solar energy [5]. It was found that the evaporative multi-step distiller uses about 40 kw in heating calories to produce fresh water at a capacity of 3 m3/day and the performance ratio (PR) value of the developed distiller was seen to be , on average. Also, it is found that the area required for solar RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 2

3 collectors to produce 3 m 3 /day on the basis of 8 hour of solar energy utilization time was approximately 512 m 2, based on solar radiation of 500 W/m 2 and collector efficiency of 60%. Madani [6] constructed a 40 m 3 /day solar-powered low temperature ME plant was constructed on the island of La Desired in the French Caribbean. The energy system consisted of a 670 m 2 of tubular collectors under vacuum and a 100 m 3 hot water storage tank. The process had 14 cell evaporators which was operated between 65 C and 26 C sea water temperature. a solar heated MED was built in Takami Island, Japan with a yearly average capacity of 10 m 3 /day [7,8].The distiller had 16 effects with horizontal-tube, thin film evaporators and a minimum and maximum capacities 5.0 m 3 /day (in winter) and 16.4 m 3 /day (in summer), respectively. A stratified vertical tank having a heat storage capacity of 38 m 3 was used to operate the distiller automatically when the water temperature in the tank reached 75 C in summer (62 C in winter) and stopped automatically when it falls to 55 C in summer (50 C in winter). The heat storage tank has accumulated enough energy to enable operation to continue overnight and during cloudy weather for several days in succession. The yearly average daily solar insolation and the daylight hours were considered to be 3240 kcal/m 2 day and 2120 h/year, respectively as design parameters. The heating energy required by the MES system was provided by the evacuated tubular collectors with the collector area of 336 m 2. The operating temperature for the solar collector was considered as C which was provide by solar energy. Applications related to solar assisted MED plant installation were performed [8] in Takashima Island in Japan and the Black Sea, Bulgaria in the same year with a plant capacity of 10 m 3 /day and 2 m 3 /day, respectively. A pilot solar MED process was developed in 2003 in Beni Khiar, Tunisia. The distillation plant consisted of 3 effects with an operating temperature of 80 C and had a capacity of L/day from seawater. The effective collector absorber area was 108 m 2 and the annual mean solar radiation was 6 kwh/m 2.day. The distillation plant was operated 10 h averagely a day. A practical scale desalination system was developed [9] to use only solar energy as the heat energy from solar collectors and the power from solar cells at the water research center in Al Azhar University. The system had triple-effect evaporators working on batch process for daily operation with brackish water. The daily highest water production was L/day in June July when the solar average daily insolation was the highest at MJ/m 2.day and the lowest production was 85 L/day in December when the solar average daily insolation reached the lowest value, MJ/m 2.day. A solar energy powered desalination pilot plant based on MED with submerged boiling was tested [10] for a small-scale remote site application in Oman. The plant had 12 effects with the type of RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 3

4 submerged tube evaporators and a design capacity of 1000 l/day in 9 h of operation during the day using the solar energy. The solar thermal subunit consisted of 16 solar modules having an aperture area of 1 m 2, each and comprised of 4 high temperature vacuum tubular solar collectors with mirror concentrators. The modules automatically tracked the sun using a tracking system. The 2m 2 photovoltaic cells were used to meet all the plant electrical power requirements. The effect of tube bundle arrangement and the seawater feed distribution on the dry zone and scale formation in the large sized Multiple Effect Distillation (MED) evaporator is evaluated in [11]. In a commercial and large scale MED desalination plant, the evaporator consists of a multi effect. Each effect consists of tube bundle, demister, and spray nozzle. In order to have a compact size tube bundle, the triangle (staggered) pitch is adopted for the evaporator. Spray nozzles are used to distribute the seawater feed on the tube bundle as shown in Figure (2). The uneven distribution among tubes in vertical columns of the tube bundle is a direct result of the conical shape of the spray nozzle which unevenly sprays the seawater. Also, the use of a triangle pitch tube bundle arrangement also contributes to this uneven distribution of flow across the tubes. Therefore, a mathematical model is developed to consider only the effect of non-uniform flow distribution among tubes due to tube bundle arrangement. A mathematical model of the seawater feed distribution is developed and validated for a triangular pitch tube bundle of MED evaporator. The developed model includes CaCO 3 scale formation and CO 2 release [11]. Membrane distillation is a newly emerging technology that requires low grade energy consumption compared to other technologies such as MSF or RO. Summarizing the benefits of membrane technology in desalination processes lies in the fact it provides continuous separation, beside the fact of the ease of combining the membrane process with thermal separation processes (hybrid strategies). Also, membrane process can be modular and flexible for scale up keeping the advantage that the separation is occurring under mild conditions. Another benefit lies in variable membrane properties which can be adjusted. Few demonstration projects using solar thermal membrane distillation (MD) have been built. First, Hogan et al. [12] describes a 0.05 m 3 /d system using 3 m 2 of solar collectors. Their system, which was tested in Sydney, consisted of a hollow-fiber membrane module for MD and a heat recovery exchanger for reducing capital costs. Later, Ding et al. [13] proposed a mathematical model that can describe the components of a solarpowered MD pilot plant. Their results showed that the proposed solar-powered MD pilot plant has some unique features, which differ from a similar MD process operated at steady-state conditions in a RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 4

5 laboratory. The analysis of the system revealed that heat recovery via an external heat exchanger is effective, and an economical way to intensify the process. Solar thermal MD unit has been installed in Jordan and operated with untreated seawater since February 2006 [14]. The unit consists of flat plate collectors, PV panels and spiral air gap membrane distillation module(s). The effect of process parameters such as brine temperature and salt concentration were investigated. Guillen- Burrieza et al. [15] experimentally evaluated the performance of an air gap membrane distillation solar desalination pilot system developed under MEDESOL project. The temperature of the feed water and its flow rate were found to have more effect on the system performance than the temperature and flow rate of cold fluid. The performance ratio of the system was below 1. It was noticed that multistage three module system was capable of reducing the thermal energy consumption. The integrated small unit of direct contact membrane distillation equipped with a solar absorber is designed and investigated [16]. The absorber inserted between glass and the membrane to assist and compensate the energy loss in the feed channel due to evaporation within membrane. The device performance is compromised under temperature of C of the hot stream while absorb solar energy. The maximum trans-membrane flux is 4.1 kg/ (m 2 h) with high purity which is 16.6 higher than the traditional membrane distillation operating under the same operating conditions without solar assist. However, the additional Capex and complexity of solar absorber need to be evaluated. Banat et al. [17] studied the possibility of producing potable water by integrating solar still with shell and tube type membrane distillation module in which heated brine from solar still was used as feed for membrane distillation unit. The distillate yield increased as brine temperature and flow rate increased. The distillate produced by solar still and membrane distillation unit was found to be 20% and 80% of the total output. Removal of arsenic from contaminated ground water using solar energy driven direct contact membrane distillation horizontal module was studied by Manna et al. [18]. The gained output ratio, thermal recovery ratio and the water flux were found to be 0.9, 0.4 and 90 kg/m 2 h at a feed temperature of 60 C, feed flow rate of 120 kg/h, permeate flow rate of 150 l/h and arsenic concentration of 396 ppb. The distillate yield decreased with the increase in arsenic content in the feed water. Wang et al. [19] studied the potential of solar heated hollow fiber vacuum membrane distillation system for potable water production from underground water in Hangzhou, China. Increased distillate yield was noticed by increasing the feed flow rate and feed inlet temperature. The reduced energy consumption was noticed by incorporating the heat recovery unit. RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 5

6 Five year performance of solar membrane distillation demonstration plant installed in Pozo Izquierdo- Gran Canaria Island (Spain), was found to be satisfactory [20]. Enhanced version of direct the contact membrane distillation unit was used for the plant and during the five year operation. The distillate production was found to vary between 5 and 120 l/d and is of high quality. The specific thermal energy consumption of the plant was in the range of kwh/m 3. Zwijnenberg et al. [21] studied the solar driven desalination process using the membrane pervaporation. The experiments were carried out with seawater from North Sea, deoiled formation water from Oman oilwell and artificial sea water. The distillate was found to be of high quality and the distillate flux was not affected by the feed concentration and fouling. Chang et al. [22] carried out experiments with fully automated solar membrane distillation desalination system which consists of hot and cold fluid thermostat, thermal storage tank, air gap membrane distillation, pumps and energy recovery unit. The hot thermostat simulates the solar absorber using the predefined values for solar radiation. Distillate yield of the system was found to be kg/d for sunny day and kg/d for cloudy day. Andres et al.[23] conducted experiments with two different experimental setups, the first step a vertical tube falling films multi-effect distiller and the second step a membrane distiller. It was found that the one stage multi-effect distiller is able to produce more than 0.5 m 3 /d distilled water with a Gain Output Ratio (the ratio of amount of distillate produced per unit of heating steam supplied to the first effect) of 4, when working at atmospheric pressure, and with a total occupation volume of 1 m 3. The distiller produced best a performance at the feed inlet temperature of 85 C and circulation flow rate of about 170 kg/hr. Under these conditions a GOR value of 3.7 and a water production of 16 kg/hr could be reached. The integration of one membrane distiller at the outlet of the multi-effect leads to an increase in the production by about 7.5%. Also, an improvement of energy efficiency is reached by 10%. In this work, experimental evaluation of a novel hybrid Multi Effect Distillation Membrane Distillation (MED-MD) driven by solar collector is presented. The new configuration solves some technical challenges of existing thermal MED desalination such as recovery ratio and wetting rate. The minimum wetting rate of the thin film horizontal evaporation MED is recommended to improve the thermal efficiency of the evaporator. However, on the other hand, the minimum wetting rate creates restriction on the recovery ratio and conversion factor of the evaporator in order to avoid dry patch zone with its consequences of scale deposits and drop in the evaporator thermal efficiency. In the existing design of the MED evaporator, the brine collected in the bottom is directed to the next effect through orifice to let another small portion of brine converted to vapor by flash vapor (only 1-2 %). Integrating MD to the RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 6

7 downstream makes use of maximum conversion factor of it through vapor pressure difference rather than flashing process. Since the vapor permeate depends on the vapor pressure difference which higher than flashing process. 2. Process Description & Experimental set up 2.1 Overall process flow diagram A novel hybrid thermal multi effect desalination (MED) and membrane distillation (MD) system power by a solar collector is presented in Fig. 1. Solar energy is used as heating source to run the new hybrid process. In order to maximize the efficiency of the solar energy system, sensible heat of the circulated fluid (pure water) is circulated in closed loop between the solar collector and tubes of the first effect of MED evaporator. This improves conversion process by excluding vapor generating unit with its complexity control system. Due to circulation of hot water in the tubes of the first effect, part of the sprayed seawater outside the tube is evaporated. This generated vapor is directed to the next effect to be used as a heating source. While the brine of the first effect (not evaporated) is directed to the first effect of membrane distillation. This brine has potential temperature which assists to another vapor permeated through membrane and condensed on the air gap side. In similar way the second effect of MED is connected to the second effect of the MD as shown in Figure 1. The generated vapor in the second effect of MED is condensed in the water condenser. The brine of the second effect of MED is directed to the MD hot side. A new permeate vapor crosses the membrane to be condensed in the air gap side. Seawater feed is directed to the condenser to condense the vapor of the second effect (cell2) MED. The seawater get worm due latent heat released. Part of this cooling seawater is directed to the MED to be sprayed on the top of the horizontal tube. The reaming part is directed to the membrane distillation to condense the permeated vapor. Solar energy is used as heating source to provide thermal energy required to MED system. In order to maximize the efficiency of the solar energy system, sensible heat of the circulated fluid (pure water) is circulated in closed loop between the solar collector and tubes of the first effect of MED evaporator. This improves conversion process by excluding vapor generating unit with its complexity control system. RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 7

8 Multi Effect Distillation Cell 1 Cell 2 Seawater Feed Solar collector Hot water Cooling water brine brine Condenser Feed Feed Cell 1 Cell 2 Disitllate Cooling reject Disitllate brine Membrane Distillation Cooling reject Fig. 1: Process flow diagram of novel hybrid MED-MD driven by solar energy Fig. 2: Experimental set up of the MED unit. RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 8

9 2.2 Solar collector set up The pressurized water is heated by solar energy in the solar system as flowing in series through four flat plate solar collectors (1) and then through three evacuated tube solar collectors (2). A pump (4) is used to circulate the water in the system. An expansion tank (5) is used as a safety measure for the system to avoid the sudden increase in pressure. A shell and tube heat exchanger are used to exchange heat between the solar system and the Multi-effect distillation (MED) unit as shown in Figure 3 Fig. 3: Solar Collector RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 9

10 2.2 Desalination system set up The proposed system uses solar energy as a heating source. The desalination process is a novel hybrid thermal multi effect desalination (MED) and membrane distillation (MD) system. The flow diagram of the proposed system is shown in Figure 2. Seawater is heated by the solar water collector and then passes through first effect of MED. Heating steam is introduced inside the tubes and then returned to solar water collector. Since tubes are cooled externally by make-up flow, steam condenses into distillate (freshwater) inside the tubes. At the same time sea water warms up and partly evaporates by recovering the condensation heat (latent heat). Due to evaporation, sea water slightly concentrates when flowing down the bundle and gives brine at the bottom of the cell. The vapor raised by sea water evaporation is at a lower temperature than heating steam. However it can still be used as heating media for the next effect where the process is repeated. The decreasing pressure from one cell to the next one allows brine and distillate to be drawn to the next cell where they will flash and release additional amounts of vapor at the lower pressure. This additional vapor will condense into distillate inside the next cell. The brine output from MED then passes to AGMD module and. The fresh water is produced from the air gap membrane distillation. The tube bundle of MED evaporator is arranged in a way to optimize the vapor route to the next effect as shown in Fig.4. The tube bundle of the first cell is put to the upper wall side while the tube bundle of the second effect is set to the lower wall side. This arrangement allow the vapor release from the first effect (cell1) to follow easy way to reach the next tube bundle of the second effect as shown in Fig.4. this arrangement offers uniform flow while approaching the next tube bundle hence reduce the thermal losses due to pressure drop in the vapor box and changing the flow vapor direction. The tube bundle specification is presented in Table1. The tube length and diameter are 0.5 m and 8 mm respectively. The number of tubes is 121 of cooper type. RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 10

11 Fig. 4: Layout of two effect MED evaporator Table 1: Specification of the evaporator and condenser Evaporator I & II Condenser Tube length, m Tube diameter, mm 8 10 Number of tubes Tube type Cooper Cooper Area, m RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 11

12 Fig. 3 photo and details of evaporator, dimensions in (mm). Fig. 5: Two-effect MED Evaporator RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 12

13 Fig.6: Two-effect Membrane distillation 2.4 Simulation tool development A simulation package VDS (Visual Design & Simulation) was developed for design and simulation of different types and configurations of desalination processes. Object-oriented programming with Visual Basic was used to simulate some operating desalination plants to offer a flexible reliable and friendly user-interface. Validity of the VDS package was demonstrated a satisfactory agreement between the calculated results and the referenced results [23]. Using well developed VDS software, the mass and heat balance of single MED teat pilot is calculated as shown in Figure The heat transfer area of the evaporator, condenser is calculated as shown in Table 1. Specifying the tube length of 1 m and diameter of 19 mm, the number of the tubes of calculated as 65. The condenser tubes length and diameter are specified as 1 m and 12 mm respectively while the number of tubes is calculated as 9. By knowing the tube number, the tube bundle is arranged in a square shape and triangle pitch as shown in Fig. 3. The tube bundle will be the test section which will be our focus in this research. The tube bundle will be designed in a flexible way to facilitate replacing tubes and easy accessing the tubes under investigation. The evaporator side wall shall be transparent to help vision by necked eye. RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 13

14 Parameter Value Number of effect, n n = 2 Motive steam temperature, T s Total product flow rate, M d Salt concentration in feed seawater, X f Salt concentration in rejected brine X 2 Seawater temperature leaving the condenser, T f Intake seawater temperature, T cw 100 o c 50 kg/hr ppm ppm 35 o c 25 o c 3. Results &Discussion The novel configuration MED-MD increases the overall recovery ratio. This is because the cooling reject of the down condenser of MED is used as cooling to the membrane distillation to get new amount of distillate for the same amount seawater feed to MED. Due to increase of the overall water production, the electrical energy and thermal energy consumption consequently would be decreased. RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 14

15 Accumulative water productivity, kg/hr Water productivity, kg/hr Figure 1 demonstrates the change of water productivity in Kg/hr with time. The results were taken on 3/4/2016 in the morning starting at 9:00 a.m. After one hour the water productivity rises to around 13 kg/hr. At 11:00 a.m., the productivity was around 17 kg/hr. It reaches its peak value of 19 kg/hr at 12:00 p.m. then it begins to decrease to 16 and 12 kg/hr at 2:00 and 3:00 p.m., respectively /4 / Time, hr Fig.1 Figure 2 illustrates the increase the accumulative water productivity with time. With test conditions of feed water flow rate to the first evaporator, feed water flow rate to the second effect are 240 and 180 kg/hr, respectively. Mixing ratio is 80 %. The accumulative water productivity increased rapidly at the first morning hours then slightly after 1 p.m /4 / Time, hr Fig.2 RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 15

16 Temperature, ᵒC Figure 3 illustrates the change of inlet and outlet solar collector temperatures with time. Both temperatures increase rapidly at the first morning hours from 9 a.m. to 12 p.m., then decreases slightly after that until 4 p.m. At 9 a.m., inlet and outlet solar collector temperatures were around 50⁰C and 60 ⁰C, respectively. At 12 p.m., they were at maximum around 60⁰C and 80 ⁰C, respectively tsco tsci / 4 / 2016 mw= 720 kg/hr Time, hr Fig.3 Figure 4 shows the change of solar radiation intensity with time on 3/4/2016. The pyranometer read 650 W/m 2 at 9 a.m. The readings increased with time until a peak value of 950 W/m2 at 12 p.m. then decresed to around 400 W/m 2 at 4 p.m Solar radiation intensity, W/m /4 / Time, hr Fig.4 Figure 5 illustrates the change of the entire system temperatures and the solar radiation intensity with time in a single diagram. The readings were taken from 9 a.m. to 4 p.m. RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 16

17 Temperature, ᵒC tci tco tbm tf td1 tv2 td2 tsco tsci td_tank tb1 tb2 G 3 /4 / Time,hr Solar radiation intensity, W/m 2 4. Conclusion The recovery ratio of the novel configuration MED-MD is higher than the individual standalone MED thermal system. This is because the cooling reject of the down condenser of MED is used as cooling to the membrane distillation to get new amount of distillate for the same amount seawater feed to MED. Due to increase of the overall water production, the electrical energy and thermal energy consumption consequently would be decreased. 5. References 1. Garc,., Renewable energy applications in desalination: state of the art, Solar Energy, 75 (2003) Eltawil, M. A., Zhengming, Z., & Yuan, L., A review of renewable energy technologies integrated with desalination systems, Renewable Sustainable Energy Rev. 13 (2009) El-Nashar, A. M., Optimizing the operating parameters of a solar desalination plant, Sol. Energy, vol. 48, no. 4, pp , Milow, B., & Zarza, E., Advanced MED solar desalination plants. Configurations, costs, future seven years of experience at the Plata forma Solar de Almeria (Spain), Desalination 108 (1997) Joo, H. J., & Kwak, H. Y., Performance evaluation of multi-effect distiller for optimized solar thermal desalination, Appl. Therm. Eng., vol. 61, pp , Madani, A. A., Economics of desalination for three plant sizes,desalination, vol. 78, pp , Noguchi, T., Overview on thermal application of solar energy in Japan, Sol. Wind Tectnolagy, vol. 2, pp , Epp, C., & Papapetrou, M., Co-ordination action for autonomous desalination units based on RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 17

18 renewable energy s y s t e m s - ADU-RES, Desalination, vol. 168, pp , Moh'd S, A. J., Kamiya, I., & Narasaki, Y., Proving test for a solar-powered desalination system in Gaza-Palestine, Desalination, vol. 137, pp. 1 6, Begrambekov B. L., The small solar MED desalination plant, MEDRC Series of R&D Reports, Project: 98-AS-024a, Oman, Mabrouk, A. A., Bourouni, K., Abdulrahim, H. K., Darwish, M., & Sharif, A. O., Impacts of tube bundle arrangement and feed flow pattern on the scale formation in large capacity MED desalination plants, Desalination 357 (2015) (ISSN: ). 12. Hogan, P. A., Fane, A. G., & Morrison, G. L, Desalination by solar heated membrane distillation, Desalination, 81 (1991) Ding, Z., Liu, L., El-Bourawi, M. S., & Ma, R., Analysis of a solar-powered membrane distillation system, Desalination, 172 (2005) Banat, F., Jwaied, N., Rommel, M., Koschikowski, J., & Wieghaus, M., Performance evaluation of the large SMADES autonomous desalination solar driven membrane distillation plant in Aqaba, Jordan, Desalination, 217 (2007) 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 (2011): system." Journal of Membrane Science 16. Chen, T. C., & Ho, C. D., Immediate assisted solar direct contact membrane distillation in saline (2010): water desalination, Journal of Membrane Science 17. Banat, F., Jumah, R., & Garaibeh, M., Exploitation of solar energy collected by solar stills for (2002): energy25.2 desalination by membrane distillation, Renewable 18. Manna, A. K., Sen, M., Martin, A. R., & Pal, P., Removal of arsenic from contaminated groundwater by solar-driven membrane distillation, Environmental pollution (2010): Wang, X., Zhang, L., Yang, H., & Chen, H., Feasibility research of potable water production via (2009): solar-heated hollow fiber membrane distillation system, Desalination 20. 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 (2012): 290 Gran Canaria Island (Spain), Desalination 21. Zwijnenberg, H. J., Koops, G. H., & Wessling, M., Solar driven membrane pervaporation for (2005): desalination processes, Journal of Membrane Science 22. 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 (2012): 286 process, Desalination 23. De Andres, M. C., Doria, J., Khayet, M., Pena, L., & Mengual, J. I., Coupling of a membrane distillation module to a multieffect distiller for pure water production, Desalination, vol. 115, pp , Nafey, A. S., Fath, H. E. S., & Mabrouk, A. A., A new visual package for design and simulation of desalination processes, Desalination 194 (2006) RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, aaboukhlewa@qf.org.qa 18

19 RM 446, Italy, Corresponding author: Abdelnasser Mabrouk, 19