Solar Desalination of Water

Over the years, the emergence of pesticides practice has prevailed to be the most intricate environmental turmoil amongst the scientific community. Specifically, pesticides constitute an accumulative, persistent and detrimental impact towards the survival of flora, fauna and environmental matrix. This has inspired a developing research with a variety of treatment technologies. Adsorption is recognized as the most efficient and promising approach, due to the ease of operation, simplicity of design, insensitivity to the toxic substances and superior capability for removing a broad range of pollutants. Its diverse applications, however, are retarded by the high cost of adsorbents and difficulties associated with regeneration. Montmorillonite and its derivatives, a unique group of under-utilized clay-based minerals has been proposed to be a suitable candidate for the treatment of contaminated wastewater. It plays a key role as the natural scavenger of pesticides, due to the abundantly a...

—The provision of fresh water is becoming an increasingly important issue in the world, in arid and semi-arid regions, as southern Europe, North Africa and the Middle East, Central Asian countries and several areas in North and South America. The water demand is linked to rapid population growth, pollution problems, climate change and the frequency of drought periods. As a consequence, more and more interest is paid to thermal desalination processes of seawater coupled with renewable energy such as solar energy. In this paper, the modeling and design of the heat exchangers in a multi-effect distillation (MED) desalination plant using thermal solar energy is presented and analyzed, specifically we focused our interest in shell and tube heat exchangers. We compared the heat transfer coefficients (HTC) found using the correlations of Bell method for Single phase , Kandlikar for Boiling correlations, Kutateladze for Condensation correlations with those present in previous experimental work for each mechanisms in MED plant. The results show the reliability of the design and that they are in good agreement with the values of previous experimental works.

The present work highlights the importance of using the Fresnel lens technique to enhance the productivity of a conventional solar still (CSS). In this regard, the effect of using Fresnel lenses to improve the productivity of a CSS is investigated experimentally under the climate conditions of Basra city (30.5258°N latitude and 47.7738°E longitude), Iraq. The Fresnel lenses integrated conventional single-slop-basin type solar still (CSS FL) adjustable to be rotated manually at different angles was examined, compared to the CSS which showed a remarkable enhancement of producing output. The study concerned the variation of daily solar radiation and temperature effect on the distillate output and the efficiency of both the conventional and modified solar stills at 1 and 2 cm saline water depths during July and September of the year 2019. The experimental results showed better performance during July where it has been found that the productivity of the CSS FL improved over the CSS by about 68.6% at 1 cm depth and about 59.3% at 2 cm depth. Moreover, the average daily thermal efficiency of the CSS and the CSS FL at 1 cm depth was 21% and 36%, respectively. Several conclusions and recommendations are presented for future work.

Recently, the world starts to suffer from the shortage of fresh water, in which it effect the survivor of people in many countries which cannot afford the costs of desalinate seawater. More than 50,000 children die every year from the shortage of fresh water. In Egypt, the need for fresh water is increasing daily due to the high demands from the growing population. Moreover, Ethiopian dam put Egypt and Sudan in a very risky situation. Egyptian North coast urban settlements are located far away from the River Nile and regular methods for seawater desalination is highly expensive as well as transferring fresh water from River Nile to north coast urban settlements is not an option. This research intends to present cheap system for seawater desalination by integrating solar glass pyramid tank with building sanitation system and replacing it with the regular building water tanks. The presented research used experimental method to investigate the efficiency of solar glass pyramid tank. The research built solar glass pyramid tank in hot arid climate region which is Cairo-Egypt, and measure the amount of seawater desalinated and compare it with the amount of water consumed in single residential house. This tank will desalinate the seawater using the solar radiation to evaporate the seawater and turn it to steam, the steam will be stored in another tank as fresh water. According to the presented research, SGP will satisfy almost 3% of the basic needs for fresh water in single-family unit in which it can satisfy the drink and cooking activity in middle class single family home. The percentage of desalinated water will increase if SGP tank were linked to heater system that accelerate the evaporation process

Desalination plays critical role in filling the gap between fresh water demand and availability in water scarce Sultanate of Oman since 1976. Installed desalination capacity in the country has almost increased by 60 times that in 1976 with increasing fresh water demand. Even though desalination share in meeting the fresh water demand is increasing, 80-85% of fresh water demand today is still satisfied with ground water. This is leading to increased soil salinity in recent years affecting the crop production. All the planned and installed desalination plants in the country use conventional fuels for their operation. None of the plant is based on any form of renewable energy source. Consumption of fossil fuels for the operation of plants is increasing at an average rate of 3-5% affecting the net export for the country. Sultanate of Oman is considered to be one of the most suitable destinations for solar energy applications and can play a vital and sustainable role in meeting the gap b...

Jordan is one of the ten most water scarce countries in the world. In 2014, the share of water per capita per year in Jordan is 120 Cubic Meters (m 3). The water deficit is estimated to be 160 Million Cubic Meter (MCM) in 2015. This deficit is projected to grow up to 490 MCM by 2025. This study discusses the possibility of using solar energy for brackish water desalination in Jordan Valley (JV) to reduce the pressure on the fresh water and the conventional energy consumption associated with the desalination process, as well as, to reduce Greenhouse Gases (GHG) emissions associated with the consumption of energy produced from fossil fuels. Photovoltaic (PV) powered brackish water reverse osmosis desalination technology (RO) has been investigated in this study. The PV system has designed using PVSOL software. The economic feasibility study of use PV system has been done using Average Incremental Cost of Water (AICOW), Internal Rate of Return (IRR) and Net Present Value (NPV) in several scenarios. The results of the analysis showed that using PV systems for brackish water desalination for a small size single plant at current electricity tariff is not economically feasible for the farmers. But it is feasible for a larger size plant for ten farms or more, or with financial support from the government. The feasibility results showed that using PV systems for brackish water desalination for the government side are economically feasible even for a small size plant.

This work presents an experimental investigation of the performance of a HDH system operated by heat pump. The novel heat pump system provides the necessary heating for the humidifier and cooling for the dehumidifier of the HDH system. The proposed integrated unit is capable of producing freshwater as well as cooling effect for space conditioning through water heated or cooled heat exchange units. Influence of various operating parameters such as feed water flowrate, feed water temperature and chilled water flowrate on the general assessment metrics, including gain output ratio (GOR), recovery ratio (RR), coefficient of performance (COP), energy utilization factor (EUF), Specific electrical energy consumption (SEEC) and productivity are evaluated. The cost of freshwater production from the proposed desalination unit is estimated. Results showed that the integrated system is capable of attaining maximum GOR of 4.07, RR of 4.86%, COP of 4.85, EUF of 3.04, and productivity of 287.8 L/day. The minimum SEEC of the system was found to be 160.16 kWhr per cubic meter of freshwater. The system is also capable of providing cooling load of 3.07 kW while producing the needed desalinated water.

Solar distillation is one of the oldest and simplest technologies for desalination of salty water using renewable energy, namely solar energy, and the main problem of solar distillers is the low freshwater yield in contrast to the amount of energy input from the sun. To overcome the problem, this study develops three solar desalination units by using solar concentrators or/and internal reflectors, and compares the performance of three developed systems with the one of a conventional solar distiller under the climatic conditions of the Rabat region of Morocco. The three systems are: the solar distiller with a solar concentrator, the solar distiller with internal reflectors, and the solar distiller with a solar concentrator and internal reflectors. The energy balance equations of the systems are numerically resolved to utilize MATLAB software. The findings indicate that the utilization of the internal reflectors, the solar concentrator, and the solar concentrator and internal reflecto...

En el proceso de desalinización del agua de mar para la producción de agua dulce se genera una gran cantidad de salmuera de rechazo que descargada directamente al mar puede causar daños ambientales significantes por la alta concentración de sales y también la presencia de bajas concentraciones de productos químicos utilizados durante la desalinización. Las noticias de estos daños han causado un rechazo en partes de la población a proyectos de desalinización por las potenciales consecuencias negativos a la industria pesquera y al turismo. Este artículo presenta un proceso integral de K-UTEC Salt Technologies como una solución viable para convertir la salmuera de rechazo en una materia prima mediante la producción de una gama de sales valiosas y otros productos secundarios, así generando un valor agregado al proceso de desalinización y al mismo tiempo evitando los impactos negativos mencionados.

Desalination is one of the most traditional processes to generate potable Water. With the rise in demand for potable water and paucity of fresh water resources, this process has gained special importance. Conventional thermal desalination processes involves evaporative methods such as multi-stage flash and solar distils, which are found to be energy intensive, whereas reverse osmosis based systems have high operating and maintenance costs.

This Report presents the different solutions to the most commonly used desalination process, and solar energy production technology compatible with desalination. The goal is to assess the feasibility and profitability of the substitution of fuel energy used for desalination plants with renewable energy. A review of various technologies will define broadly features associated to each technology and range of cost that are expected. Finally, a review of various projects will detail the practical aspects of floor space and actual production costs of fresh water. The world-wide availability of renewable energies and the availability of mature technologies in this field make it possible to consider the coupling of desalination plants with renewable energy production processes in order to ensure the production of water in a sustainable and environmentally friendly scheme for the regions concerned.

Solar desalination is used by nature to produce rain which is the main source of fresh water on earth. All available man-made distillation systems are duplication on a small scale of this natural process. Recently, considerable attention has been given to the use of renewable energy as sources for desalination, especially in remote areas and islands, because of the high costs of fossil fuels, difficulties in obtaining it, attempts to conserve fossil fuels, interest in reducing air pollution, and the lack of electrical power in remote areas.

Humidification-dehumidification is a carrier gas based thermal technique that is ideal for small-scale water desalination applications. One advantage of humidification-dehumidification systems is the ability to utilize low grade and renewable energies as heat source to drive the system. This work presents theoretical investigation of humidification-dehumidification desalination system operated by a heat pump. The model is based on the first law of thermodynamics, describing heat and mass transfer in the combined humidification-dehumidification-heat pump cycle. The model predicts the performance of closed-air open-water water-heated, and modified air-heated cycle coupled with a heat pump. To improve the Gain output ratio and energy recovery of the system, a heat pump is used as the source of heating and cooling for the humidification-dehumidification desalination system. Energy rejected in the condenser is used as a source of heat in the humidifier whereas the cooling effect of the evaporator is used to cool incoming seawater for effective condensation of humid air in the dehumidifier. A parametric study is conducted to investigate the influence of system operating parameters, including water and air flowrate, seawater temperature, and refrigerant flow rate on the system performance. Results indicate a maximum Gain output ratio of 8.88 and 7.63 obtained at 80% components effectiveness and mass flow rate ratio of 0.63 and 1.3 for modified air heated and water heated cycle, respectively. A maximum gain output ratio greater than 10 can be achieved for humidifier and dehumidifier effectiveness of 100% leading to more energy efficient systems. The cost of desalinated water production is calculated and the effect of major parameters on its variation is also presented.

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright a b s t r a c t Seawater desalination is an important process to meet the increasing demand for fresh water demand; however, it is highly energy intensive due to the high salinity of the source. Studies on using solar energy to drive seawater desalination are very actively being pursued. This paper reviews the current solar desalination research activities first, followed by discussions of solar assisted desalination processes and a variety of possible combinations. Solar assisted desalination has been proved technically feasible; however the combined solar and fossil fuel desalination, and desalination using low grade waste heat could be more cost effective at this time. Though solar assisted desalination processes have not been commercialized as yet, with the current ongoing research, they remain a valid option for future desalination plants. Published by Elsevier Ltd.

This paper presents an overview of using solar energy in running desalination systems,
called solar desalination. Solar energy can be converted directly to electric energy, which
can operate electrically driven desalting systems such as reverse osmosis (RO), electrodialy-
sis (ED), and mechanical vapor compression systems. Solar energy can also be converted to
the thermal energy that can operate the mainly used thermally operated desalination system
such as multistage flash (MSF), conventional multieffect (ME), and multieffect thermal
vapor compression (ME-TVC), and emerging membrane distillation and humidification–
dehumidification desalination systems. The thermal energy converted from solar energy can
also be used to produce high-pressure steam running power plant producing electric power
to operate mechanically driven desalting systems, and/or extracted steam at relatively low
pressure to operate thermally driven desalting system. The main obstacle that hinders the
use of solar desalination is the initial investment cost. This paper discusses the use of the
solar desalination and calculates the investment cost to install solar desalination plants.
These include photovoltaic (PV)-driven RO system, and thermally driven MSF and ME
plants by steam directly generated by solar collectors, or by steam extracted from solar
steam power plants operated by the concentrated solar collectors. The results revealed that
PV-RO desalting system has the highest specific capital cost, among the considered systems,
because the expensive storage of the electric energy in batteries, and the fact solar energy
supply lasts about one third of the day. It showed also that using the thermally generated
energy from concentrated solar collectors operating power plant is much cheaper than using
this thermal energy when directly operating the desalination system.

Desalination plays a critical role in filling the gap between freshwater demand and availability in water-scarce Sultanate of Oman since 1976. Installed desalination capacity in the country has almost increased by 60 times that in 1976 with increasing fresh water demand. Even though desalination share is increasing, 80-85% of freshwater demand today is still satisfied with groundwater and natural sources. This is leading to increased soil salinity in recent years affecting the crop production. All the planned and installed desalination plants in the country use conventional fuels for their operation. None of the plants are based on any form of renewable energy source. Consumption of fossil fuels for the operation of these plants is increasing at an average rate of 3-5% affecting the net export for the country. Sultanate of Oman is considered to be one of the most suitable destinations for solar energy applications and solar energy can play a vital and sustainable role in meeting the gap between the demand and supply of fresh water using solar thermal desalination. This paper emphasizes on addressing this aspect for the country. An overview of present desalination status and fresh water demand, fuel requirements, solar energy availability, thermal desalination technologies and solar thermal technologies has been presented in the paper. Conventional thermal desalination technologies and solar thermal technologies have been compared for same capacity on the scale of 1 to 5 for various factors in the context of Sultanate of Oman. Few of the challenges and barriers in the implementation of solar thermal desalination in the country are also discussed in the paper. Fixed focus type Scheffler dish reflectors (SDR) are suggested as one of the best suitable option to be coupled with multi-effect desalination technology for small to medium capacity decentralized type plants. Parabolic trough collectors (PTC) coupled with Combined Cycle Gas Turbine (CCGT) or Open Cycle Gas Turbine (OCGT) plants would be a feasible solution for higher capacity desalination plants.

This paper tackles an optimization approach in order to boost the fresh water production of a new design of a solar still which is lo-
cated at Sfax engineering national school in Tunisia. This optimization approach is based upon the above mentioned design's improvement
by
coupling
the
conventional
solar
still
into
at
a
condenser,
solar
air
and
water
collector
and
humidifier.
This
new
concept
of
a
distiller
solar
still
using
humidification-
dehumidification
processes
(HD)
is
exploited
for
the
desalination
purpose.
As
a
result
of
this
work,

the

humidification- dehumidification processes have an essential effect in improving the solar still performance. Performance has been predicted theoretically in terms of water and inner glass cover temperatures, the inlet temperature of air and water of the new concept of distiller on water condensation rate and fresh water production. A general model based on heat and mass transfers in each component of the unit has been developed in steady dynamic regime. The developed model is used, simulating the HD system, to investigate the influence

of the meteorological and operating parameters on the system productivity. The obtained set of ordinary differential equations has been converted to a set of algebraic system of equations by the functional approximation method of orthogonal collocation. The developed

model is used to simulate the HD system in order to investigate the steady state behavior of each component of the unit and the entire system exposed to a variation of the entrance parameters and meteorological conditions. The obtained results were compared with those of other studies and the comparison gives a good validity of the present results. 

Keywords: Condenser; Desalination; Dehumidification; Humidification; Solar still

Membrane distillation (MD) is a developing thermally driven membrane desalination technology that has been applied in four different basic configurations. In membrane distillation, a hot, saline feed stream is passed over a hydrophobic membrane. The temperature difference between the two sides of the membrane leads to a vapour pressure difference that causes water vapour to permeate through the membrane pores, and then condensed on the cold side of the membrane. The hydrophobicity of the membrane prevents the liquid from passing through the pores, while the water vapour is allowed to pass through. The technique offers the attractiveness of operation at atmospheric pressure and low temperature (40– 90oC), and has the theoretical ability to achieve 100% salt rejection. Thus, low-grade energy like solar and waste energy can be used for desalination.
In this work, an experimental investigation of the performance of Air Gap Membrane Distillation (AGMD) system was performed for seawater and laboratory prepared salt feed water solutions. The influences of  system operating parameters such as feed temperature, feed flow rate, coolant temperature, coolant flow rate and air gap width on permeate flux were studied. The effects of membrane pore size as well as the concentration of feed solution on permeate flux were also investigated. The performance of the AGMD unit was statistically optimized using design of experiment (DOE) and Taguchi technique. Furthermore, theoretical model describing heat and mass transfer analysis in AGMD was developed and discussed in detail.
The permeate flux was found to increase with increasing feed temperature and feed flow rate. However, it decreased with increasing air gap width and coolant temperature. The system performance tends to increase marginally with increasing coolant flow rate. The system performance is mostly dominated by the effect of both feed temperature and air gap width. Feed flow rate and coolant temperature have relatively considerable effect on flux. Increasing the membrane pore size from PTFE 0.22µm to PTFE 0.45µm leads to about 10% increment in flux production. While increasing the feed concentration from 0.075g/L to 60g/L lead to about 11% drop in permeate flux. The tested double-stage AGMD design was capable of achieving a maximum permeate flux of 128.46kg/m2hr, which is almost twice that of single stage unit, under the same experimental conditions.
In general, the theoretical model results were found to be in good agreement with the experimental data as the maximum deviation of model results was within 15%. The model was also used to predict thermal efficiency and temperature polarization of the AGMD system.
Regarding system optimization using Taguchi methodology, the developed model proved to be in good agreement with the experimental data with a maximum deviation of about 10%. According to Taguchi orthogonal arrays, the experimental and model optimum system performance was found to be 76.0457 kg/m2h, and 74.5916 kg/m2h respectively. The conditions for the optimum performance are 80oC feed temperature, 5 L/min feed flow rate, air gap width of 3mm and coolant temperature of 20oC.

A B S T R A C T Being 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 CO 2 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 is less demanding regarding vapor space and building material's quality leading to potential lower construction costs. The aim of this paper is to present the state-of-the-art review of developments in solar MD technology. In this review, membrane configurations, module design, and recent applications of this technology were discussed in detail.

The coupling of a double-effect absorption heat pump and a multi-effect distillation unit was demonstrated at the Plataforma Solar de Almería (CIEMAT), Spain, within a solar desalination research project. Improvements that were identified have been implemented in a new prototype within the framework of the European project entitled AQUASOL (March 2002 – February 2006). The prototype, which will be tested during the demonstration phase of this project, is expected to consume about half of the multi-effect distillation unit but at a higher temperature, 180 °C. This paper points out different advantages of coupling an absorption heat pump to a multi-effect distillation system which could significantly increase the competitiveness of both conventional and solar powered multi-effect distillation plants. In addition, this paper shows that intensive research should be carried out for optimising and assessing such a desalination system.

Desalination technologies and industry have advanced significantly in the past two decades to meet the growing freshwater demands stimulated by the compounding issues of both water quality and quantity in many regions of the world. As desalination processes are energy demanding, there have been many efforts dedicated to improve energy-efficiency of the process units, enhance energy conservation and recovery, and increase renewable energy integration in desalination plants. This perspective article highlights recent key advances and discusses possible venues for further development in desalination energy portfolio to reduce specific energy consumption and, via integration with solar energy, to minimize the environmental footprint associated with freshwater production. First, an overview of current desalination technologies and their energy requirements are presented followed by a discussion on opportunities for improving energy efficiency and energy recovery in both membrane and thermal desalination technologies. Then, various combinations of renewable energy driven desalination plants are discussed with some recent highlights in solar energy driven membrane, thermal and hybrid desalination processes. Technological readiness levels for novel desalination processes, their perceived impact and expected near-future developments in renewable energy integrated desalination technologies are presented. Finally, the potential for solar driven desalination as a cost-competitive freshwater supply alternative is discussed.

Solar power plant is dependent on the transformation of sunlight into electricity, either
directly using photovoltaic (PV), or indirectly using concentrated solar power. Photovoltaic’s a
simple and elegant method of harnessing the sun's energy. PV modules (solar cells) are unique in that
they directly convert the incident solar radiation into electricity, with no noise or pollution making
them robust, reliable and long lasting. In this analysis, an attempt has been made for evaluating effect
of maintenance on energy efficiency, CUF and PR and performance evaluation by annual CUF and
PR of 62 KWp Grid-connected rooftop solar PV plant. Applying the first law of thermodynamics,
energy analysis was accomplished .The operating and electrical parameters of a PV array comprise
PV module temperature, open-circuit voltage, short-circuit current, fill factor, etc. were
experimentally determined and tabulated for two days (1 Dec. 2016 and 5 Dec. 2016) at Jaipur. The
performance and efficiency parameters have been studied and compared for both the days i.e. before
and after maintenance. Results showed that the performance parameters can be improved by
removing the dust and dirt or by cleaning the modules at regular interval.

The world’s energy markets rely heavily on the fossil fuels coal, petroleum crude oil, and natural gas as sources of thermal energy; gaseous, liquid, and solid fuels; and chemicals. Since millions of years are required to form fossil fuels in the earth, their reserves are finite and subject to depletion as they are consumed. The only natural, renewable carbon resource known that is large enough to be used as a substitute for fossil fuels is biomass. This article gives an overview of the state-of-the-art of key biomass conversion technologies currently deployed and technologies that may play a key role in the future, including possible linkage to CO2 capture and sequestration technology (CCS). In doing so, special attention is paid to production of biofuels for the transport sector, because this is likely to become the key emerging market for large-scale sustainable biomass use. A range from 200 to 300 EJ may be observed looking well into this century, making biomass a more important energy supply option than mineral oil today. A key issue for bio-energy is that its use should be modernized to fit into a sustainable development path. Especially promising are the production of electricity via advanced conversion concepts (i.e. gasification and state-of-the-art combustion and co-firing) and modern biomass derived fuels like methanol, hydrogen and ethanol from ligno-cellulosic biomass, which can reach competitive cost levels within 1–2 decades (partly depending on price developments with petroleum). The gasification route offers special possibilities to combine this with low cost CO2 capture (and storage), resulting in concepts that are both flexible with respect to primary fuel input as well as product mix and with the possibility of achieving zero or even negative carbon emissions. Further biomass market development, consistent policy support, RD&D efforts and international collaboration are essential to achieve this.

—The provision of fresh water is becoming an increasingly important issue in the world, in arid and semi-arid regions, as southern Europe, North Africa and the Middle East, Central Asian countries and several areas in North and South America. The water demand is linked to rapid population growth, pollution problems, climate change and the frequency of drought periods. As a consequence, more and more interest is paid to thermal desalination processes of seawater coupled with renewable energy such as solar energy. In this paper, the modeling and design of the heat exchangers in a multi-effect distillation (MED) desalination plant using thermal solar energy is presented and analyzed, specifically we focused our interest in shell and tube heat exchangers. We compared the heat transfer coefficients (HTC) found using the correlations of Bell method for Single phase , Kandlikar for Boiling correlations, Kutateladze for Condensation correlations with those present in previous experimental work for each mechanisms in MED plant. The results show the reliability of the design and that they are in good agreement with the values of previous experimental works.

The experimental modifications were carried out into the conventional solar still, considerably increasing
the distillate water productivity. The effects of using different types of nanomaterials on the performance
of solar still were studied. The investigated solid nanoparticles are the cuprous and aluminum oxides. The
performance was investigated at different weight fraction concentrations of nanoparticles in the basin
water with and without providing vacuum. These additions and modifications greatly improve the
evaporation and condensation rates and hence the distillate yield was augmented. The research was
conducted for range of concentrations starting from 0.02% to 0.2% with a step of 0.02%. The maxima
productivity was obtained for using the cuprous oxide nanoparticles with a concentration of 0.2% with
operating the vacuum fan. The results obtained that using cuprous oxide nanoparticles increased the distilled
productivity by 133.64% and 93.87% with and without the fan respectively. On the other hand, using
aluminum oxide nanoparticles enhanced the distillate by 125.0% and 88.97% with and without the fan
respectively as compared to the conventional still. The estimated cost of 1.0 l of distillate are approximately
0.035$, 0.045$ when using the cuprous oxide nanomaterial with and without the fan and, as well
as the aluminum oxide nanoparticles, 0.038$ and 0.051$ respectively, and for the conventional still is
0.048$.

This paper investigates the feasibility of using solar energy coupled to reverse osmosis (RO) units for the desalination of brackish water in the Jordan Valley, the food basket for the West Bank, Palestine. Pilot-scale RO units are appropriate because of the low energy requirement, market availability, size and area and convenience of installation in the Jordan Valley's harsh conditions. The study concerned the Marj Naajeh desalination unit. The economic feasibility was compared to other alternative energy sources (diesel generators and network electricity). The environmental costs were considered as well as the economic costs. The results obtained suggest upgrading 162 agricultural wells of different water capacities and quality. Further studies on design capacity and efficiency of future desalination facilities would be beneficial.

Membrane Distillation (MD) is a thermally driven membrane Separation technique that is used for water desalination by separating water vapor from feed salty/brackish water using micro-porous hydrophobic membrane.
Comprehensive experimental and theoretical studies on the performance of an air gap membrane distillation (AGMD)  System are presented. The effects of main operating and design variables on the permeate flux are reported. The design of the AGMD module and the experimental setup are presented in details. PTFE membranes of two different pore sizes are characterized and tested. Results show that the system  Performance is highly affected by changes in both feed temperature and air gap width. Increasing the feed temperature from 40 °C to 80 °C increases the flux by 550% to 750%, depending on the other operating variables. A maximum of 130% rise in flux, approximately, was achieved when the air gap width was decreased from 7mm to 3mm. The maximum
permeate flux obtained from the current AGMD system is 71.1 kg/m2 hr. The measured salt rejection factor is above 99.9% that emphasizes the suitability of the AGMD system for desalination of high concentration feeds.
A theoretical model based on the analysis of heat and mass transfer is developed to predict the permeate flux and to study the system efficiency. The theoretical model is validated by comparing the permeate flux with experimentally measured values where a maximum deviation of 15% is observed. The evaporation efficiency of the AGMD module and the temperature polarization coefficient are thoroughly investigated theoretically at different operating parameters.

In this study, exergo-economic analysis of two layouts of humidification-dehumidification (HDH) desalination systems driven by a vapor compression heat pump (HP) is presented and discussed. The systems are closed-air open-water water-heated cycle coupled with a heat pump (HP-HDH-WH), and modified air-heated cycles integrated with a heat pump (HP-HDH-AH). For the purpose of comparison, a conventional closed-air open-water (CAOW) electric water heated HDH system (E-HDH-WH) is also presented. Exergy destruction, exergetic efficiency and product cost are evaluated for these systems. The influence of input parameters such as mass flowrate ratio, dehumidifier effectiveness, compressor isentropic efficiency, and feed water temperature on second-law efficiency and exergy destruction associated with the major components of the systems are analyzed. The impact of input cost parameters is investigated using two different approaches. The analysis shows that evaporator and compressor are the components with the largest exergy destruction. The exergy efficiency for the HP-HDH air-heated unit, HP-HDH water-heated unit, and E-HDH water-heated unit is found to be 1.097%, 0.06965% and 0.05795%, respectively. The cost of desalinated water evaluated by current analysis for HP-HDH air-heated system, HP-HDH water-heated cycle, and E-HDH water-heated unit is found to vary from 4.61$/m 3 to 5.49$/m 3 , 6.00$/m 3 to 7.14$/m 3 , and 4.44$/m 3 to 14.95$/m 3 , respectively. The results generally reveal that HP-HDH air-heated cycle shows better performance both from energetic and exergetic viewpoints.

A B S T R A C T Water scarcity is a problem in remote locations, and producing fresh water in remote areas is an expensive process. The objective is to evaluate the optimum PV system to power BWRO desalination system that can produce 60 m 3 /d at constant daily load profile for locations at different latitudes ranging from 60˚S to 60˚N worldwide. Different design configurations are simulated using ROSA software. Simulations showed that two-stage RO system is the better option with lower energy consumption. Hybrid optimization model for electric renewables (HOMER) is used to evaluate a range of equipment and design options over varying constraints and sensitivities in terms of sizing for the economic optimization of the PV power system. The minimum initial cost of the PV system is $102,000 and found at latitudes 50˚S/N, while the maximum initial cost is $133,000 and found at latitude À60˚. The economic performance of the PV system is then optimized under Malaysia latitude by allowing portions of the annual load to go unserved. The result shows that the optimum combination is a system with a 28 kW PV array, 76 batteries, and 12 kW converter with 1.5% annual unmet load fraction at 2˚of PV slope. Allowing a small percentage of loads to go unserved throughout the year reduces the cost of the system. Powering RO system with PV power showed different initial cost for different latitudes.

Drought and scarcity of water resources require innovative and sustainable solutions to secure water availability for poor people. Choice of solar energy for desalination is a promising and sustainable cost-effective alternative for improving high quality water supply. Today, almost all Latin American countries use different desalination technologies except for Bolivia. Bolivia has an arid to semiarid climate and suffers from salinity problems especially the Altiplano area. Thus, there is a need to introduce innovative solution using latest technologies such solar desalination at locations with scarcity of freshwater. This study suggests implementing a small desalination plant of about 10 m 3 /day as a demonstration plant and then successively extending the capacity. As well, it is suggested to build a solar energy system with bigger capacity to cater not only for the desalination plant, but also the excess energy to be benefit for homes, roads lighting, and other important purposes for the local community to improve life standard of the people.

This research is intended to design and manufacture a multilayer solar distiller at a promising cost. The solar distiller manufactured has the same design as simple water distillers, which are based on the principle of evaporation and condensation with a different energy cycle, where the processes of evaporation and condensation are completely isolated. The obtained results showed that the amount of produced water has increased by 60% compared to the traditional solar distillers, where the system is not isolated. No catalysts were used, and the areas of the evaporation and condensation have also been increased leading to the production of distilled water under natural conditions and low cost. A comparison between the theoretical and experimental results is performed. The productivity was as follows: 8.45, 11.04, 12.20, 21.44, 18.69, 16.15, and 14.49L/day in January, February, March, September, October, November, and December, respectively.

Solar desalination is a rapidly growing field of research. The coming global oil crisis implies that alternatives to the conventional desalination plants based on fossil fuels must be developed. Solar desalination can be either direct, with collectors and condensers integrated with each other, or indirect, with condensers externally connected to the condensers. Direct solar desalination requires large land areas and has a relatively low productivity compared to the other technologies. It is however competitive to other desalination plants in small-scale production due to its relatively low cost and simplicity. This paper deals with the method to improve the efficiency, by combining Direct solar desalination plant with Organic Rankine cycle and a geo–heat exchanger to produce power, salt & pure water effectively.

In the world, demand of portable fresh water is increasing day by day because of population explosion all over the world, greater industrial development, expansion of agricultural activities and climate change. The available underground and surface water sources are being affected by salinity, industrial and agricultural wastes, limit the suitability of many fresh water availability resources. Now it is recognized that freshwater is a scare resources and more country is converted into water-stressed country due to the scarcity of freshwater resources. Therefore, this project was undertaken to study the performance of tubular solar still for desalination purpose. At first, a low cost tubular solar still was designed and constructed using locally available materials. Field experiment was carried out on constructed unit located on the roof top of the Civil Engineering Department, KUET, Khulna, Bangladesh from January 01 to April 30, 2011. The hourly output and ambient air temperature data was also collected in some typical days (2, 3 and 10 May, 2011) to show the effect of air temperature on productivity of tubular solar still. The analysis shows that the production rate of a tubular solar still is mainly depend on the intensity of solar radiation and the production rate will be higher in the summer season. It was observed that average daily distilled output of Tubular solar still increases for the months January to March except for the month April. It is founded that the average daily production rate of tubular solar still was 0.302lit/day (1.885lit/m2-day) and the production cost of distilled water was Tk.0.453/lit. The construction, operation and maintenance of tubular solar still are easier. So, one can easily construct a tubular solar still using locally available material to produce fresh water from saline water in the remote, coastal and arid areas to meet small scale fresh water demand.