Search

• Thermoelectric materials can convert heat into electricity and vice versa. • The applications of thermoelectric materials are cooler, heater, and generator. • The heater heats the absorber, and the cooler cools the cover or the condenser. • Thermoelectric materials improve the solar still performance. • Solar still becomes a hybrid system providing electricity and potable water using the generator. Solar still is a convenient tool for water desalination using solar energy, but it has low efficiency. Thermoelectric materials can convert thermal energy into electrical energy and vice versa. Thermoelectric materials have several applications in solar still water desalination systems. They can be used as a cooler to improve the performance of the solar still condenser or as a heater to enhance the evaporation process by increasing the temperature of saline water in the basin. Also, they can be used to generate electricity from thermal energy in solar still. The most significant modifications to solar still for producing potable water from saline or brackish water using thermoelectric materials are discussed and compared. It can be concluded that thermoelectric materials improve the performance of the solar: thermoelectric heaters or coolers increase the yield, and thermoelectric generators generate electricity as a hybrid system. More studies should be performed to address the nocturnal electricity generation, and the application of thermoelectric material with solar still's accessories such as solar collector and adsorption unit. [ABSTRACT FROM AUTHOR]

The low freshwater production of the solar distillers is one of the most crucial obstacles to their effective use in distillation applications. In this work, an attempt has been made to ameliorate the distilled yield of the hemispherical solar distiller. This was fulfilled by using a v-corrugated basin and reversed solar collector in order to augment the evaporation area and assist in reflecting more solar irradiance onto the outer surface of the v-corrugated basin. Two hemispherical solar distillers, namely; v-corrugated basin hemispherical distiller integrated with a reversed solar collector (VBHD-RSC) and traditional flat basin hemispherical distiller (TFBHD) were designed and examined at the same outdoors conditions of El-Oued (33°27′N, 7°11′E), Algeria. Moreover, a comparative energic-economic analysis of the two proposed hemispherical distillers has been conducted in terms of freshwater productivity, daily energy efficiency, and freshwater distillate cost. The results show that the daily accumulative yield of the VBHD-RSC was 7.85 kg/m2.day which was higher than that of TFBHD by 68.82%. Moreover, the daily energy efficiency was obtained to be 59.70% and 35.52% for VBHD-RSC and TFBHD, respectively. Furthermore, the economic assessment indicates that the usage of a v-corrugated basin embedded with a reversed solar collector was more cost-efficient as it reduces the cost of freshwater production by 27.12% compared to TFBHD. [ABSTRACT FROM AUTHOR]

• Hemispherical solar still of different metal trays is investigated. • Three types of trays (copper (THSSC), zinc (THSSZ), and iron (THSSI)) were studied. • THSSI containing the iron tray was about 1.17 times the daily productivity of CHSS. • THSSC with copper structure showed 53.125% increase in productivity compared to CHSS. • Thermal efficiency of CHSS, THSSI, THSSZ and THSSC were 37.4%, 42.8%, 49% and 57.2%, respectively. In this manuscript, a hemispherical solar still with different metal trays (copper, zinc, and iron) painted with black was studied experimentally. Four hemispherical solar stills were manufactured; the first is the conventional hemispherical solar still which represent the reference case (CHSS), the second, third and fourth were the modified hemispherical solar stills with adding black metal trays of copper, zinc, and iron, respectively. These trays were placed at the bottom of the distiller basin. This modification led to a significant increase in the rate of evaporation of the salt water in the distiller basin due to the improved heat transfer characteristics. The basin water depth in the trays are kept constant at 10 mm in all experiments. The results showed that the accumulative yield of the hemispherical solar still reached to 4.8 kg/m2/day, while the utilization of iron, zinc and copper trays improved the accumulative yield to 5.5, 6.3 and 7.35 kg/m2/day, respectively. These results presented that the trays hemispherical solar still of iron (THSSI) was about 1.17 times the daily productivity of CHSS, while trays hemispherical solar still of zinc (THSSZ) showed an increase in productivity by 31.25% compared to CHSS. Moreover, the trays hemispherical solar still of copper (THSSC) gave improved productivity by 53.125% compared to CHSS. The thermal efficiency of CHSS, THSSI, THSSZ and THSSC were 37.4%, 42.8%, 49% and 57.2%, respectively. [ABSTRACT FROM AUTHOR]

This paper offers a study on a modified solar power driven hybrid desalination system (SS-HDH). SS-HDH system consisting of a solar still (SS) and air humidification dehumidification (HDH) unit integrated with solar air-water heater. This study is implemented experimentally under the real daytime starting at 8:00 AM until 6:00 PM. The variations on the SS-HDH system performance and productivity, according to the different operating conditions were studied. The proposed hybridization method between HDH and SS units has led to a significant effect on the performance and productivity of both of them. The maximum productivity of the system reached to 18.25 l/m 2  day at mass flow rates of air and water equal 0.03 kg/s. The humidification efficiency reached about 79% and affected by increment on water mass flow rate more than the increment on the air mass flow rate. The system overall efficiency varies from 21% to 39%. The SS-HDH system performance influenced strongly by air mass flow rate. Gain output ratio (GOR) of about 2.57. Moreover, the smallest distilled water cost of 0.0081 US $/liter is achieved with the case of productivity equal 18.25 l/m 2  day. The uncertainty in calculating of performance parameters was about 5.68–7.8%. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation of a hybrid system of indirect evaporative air cooler and HDH desalination system assisted by solar energy for remote areas. Due to the unavailability of fresh water sources and as a result of rising ambient air temperature in most remote areas, the proposed system is a good option for these remote areas. In order to achieve this goal in remote areas, the practical apparatus proposed in this study consists of two sub-systems: (i) indirect evaporative air cooler with baffles, which can use to human thermal comfort issues, (ii) HDH desalination system assisted by the solar energy, which can use to produce the freshwater. The results of the experimental study showed that the cooling load was ranged between 253.26 and 417.4 W, accumulated distillate water productivity was 38.65 l/day, and the coefficient of performance ranged between 0.214 and 3.49 at the air flow rate of 70 m 3 /h during the period 8:00 am–6:00 pm. Also, as the secondary air flow rate increases from 60 to 90 m 3 /h, accumulated distillate water productivity increases from 35.78 to 47.21 l/day, and average daily coefficient of performance increases from 1.78 to 2.256. The proposed system in this study represents an effective and good selection in remote areas. [ABSTRACT FROM AUTHOR]

The effects of solar energy and Phase Change Material (PCM) on the energy saving of a desiccant air conditioner have been numerically investigated. Three configurations of desiccant air conditioner (Type A, Type B, and Type C) are investigated at the same ambient conditions to get beater configurations for the energy-saving potential. The difference between the three configurations represents the source of thermal energy used for heating the regeneration air used for reactivation the desiccant material. For Type A the electrical air heater represents the thermal energy source for heating the regeneration air. For Type B the solar energy and electric air heater represent a source of thermal energy for heating the regeneration air. For Type C the solar energy, PCM, and electric air heater represent a source of thermal energy for heating the regeneration air. The numerical results of these simulations are validated by published experimental data, which resulted great agreement between numerical results and experimental data. Also, the economic analysis has been studied to get the beater configurations. The results show that, the average percentage savings in the electrical energy which consumed about 20.85% for Type B and 75.82% for Type C as compared to the Type A. [ABSTRACT FROM AUTHOR]

In this study, the performances of a solar energy assisted hybrid desiccant air conditioning system integrated with humidification–dehumidification (HDH) desalination system are numerically investigated. The aim of this study is to benefit from the temperature rise of the regeneration air outside of the desiccant conditioning system as well as the water vapor content in this regeneration air by feeding it to the humidification-dehumidification water desalination unit to produce distillate water. The distillate water productivity, human thermal comfort issues, and energy saving represent the main objective of the present numerical study. The simulated results developed for subsystems are validated with the published experimental results. The effects of regeneration air temperature and flow rate on supply cooled air temperature, distillate water productivity, the cooling coefficient of performance and overall daily coefficient of performance of the proposed system are investigated. The results show that (i) the distillate water productivity increases from 3.175 to 5.011 L/h and overall daily coefficient of performance decreases from 4.392 to 3.636 with increasing the regeneration air temperature from 75 to 95 as (ii) the increase in the regeneration air flow rate from 70 to 130 m 3 /h, increases the distillate water productivity from 2.988 to 4.78 L/h and decrease the overall daily coefficient of performance from 4.66 to 3.386. The study demonstrates that the proposed system represents the best options in hot and humid regions. [ABSTRACT FROM AUTHOR]

In the present study, two solar stills were assembled and experienced to evaluate the yield and energy performance of an improved passive solar desalination system compared to a conventional one. The improved still is incorporated with a latent heat thermal energy storage medium and a parabolic solar concentrator. A parabolic solar concentrator was added to concentrate and increase the amount of solar irradiance absorbed by the still basin. Paraffin wax was applied as phase change material (PCM) in the solar still bottom plate. In the current study also, the effect of impure water profundity inside the still on still’s accumulated yield have been assessed. The following study involved a mathematical analysis for calculation of the exergetic proficiency as an efficient tool for the optimization, and yield evaluation of any energy systems and solar stills as well. Experimental research conducted in steady days of summer and winter at six different values of impure water profundity inside the solar still basin. The salinity of the impure water tested was about 3000–5000 ppm, while the salinity for the resulted drinkable water was about 550–500 ppm. The performed outcomes revealed that during summer, exergetic efficiency is higher than its qualified value in winter with approximately (10–15%) for the same water profundity. Results also disclosed that, the exergetic efficiency is higher when the water profundity in the basin is lower with approximately (6–9%). The experimental findings reveals that, the solar still with PCM and parabolic concentrator is higher in the daily freshwater yield in summer with an amount of (55–65%) and in winter with an amount of (35–45%) compared to the usual solar based still. The current work performed during January 2016 as a winter season, and July 2016 as a summer season from 8:00 am to 6:00 pm under the climate conditions of Tanta city-Egypt. [ABSTRACT FROM AUTHOR]

The performance of a cylindrical parabolic concentrator with focal pipe - coupled with a developed solar still with (oil heat exchanger, Phase Change Material (PCM)) have been experimentally investigated to improve the freshwater productivity. The cylindrical parabolic concentrator with focal pipe and oil heat exchanger (serpentine loop) represent the external heat source to increase the temperatures of the basin water and PCM. The PCM used as a heat storage medium. The influences of high heat exchanger oil temperature on the performance of the developed solar still are experimental investigated. A comparison between a developed solar still and the convenstional solar still is carried out to evaluate the enhancement in the freshwater productivity under the same ambient conditions. The experimental results indicated that, the freshwater productivity approximately reached 10.77 L/m 2 day for the developed solar still, while its value is recorded 4.48 L/m 2 day for conventional solar still. The freshwater productivity of the developed solar still is 140.4% higher than that of the conventional solar still in average. Also, the daily efficiency approximately reached 25.73% for the developed solar still, while its value is recorded 46% for conventional solar still. The percentage decrease in the daily efficiency for the developed solar still about 44% compared to the convenstional solar still in average. In the present experimental work the estimated cost of one liter of freshwater productivity reaches approximately 0.1359 LE (0.0174 $) and 0.1378 LE (0.0177 $) for developed solar still and conventional solar still, respectively. This results is obtained during the period from June to August 2015 under the Egyptian conditions. [ABSTRACT FROM AUTHOR]

Experimental investigation of a hybrid-solar desalination system consisting of a humidification–dehumidification unit and a solar distiller unit. At El Mahalah city- Egypt in climatic conditions, experimental work was performed under real thermal conditions in September 2021. A new design of helical humidifier and multi-section solar distiller has been tested. There is good agreement between the predicted and measured changes in water production and performance parameters. According to testing and operating parameters, the system's highest productivity was 6.7 kg/m2 per day at a production cost of 10.4 $/m3. System performance was tested and represented by system efficiency, humidifier efficiency, and gain output ratio (GOR). The system efficiency, humidifier efficiency, maximum gain output ratio, and exergy efficiency reached 95%, 98%, 1.65, and 7.2%, respectively. The proposed hybrid desalination system gives an adequate operational compatibility between the HDH method and solar energy. [Display omitted] • An experimental study for a solar hybrid desalination system has been conducted. • The highest productivity of the proposed system was 6.7 kg/m2 per day. • The overall system efficiency reached 95% with an average water cost of 10.4 $/m3. • Exergy efficiency and maximum GOR reached 7.2% and 1.61, respectively. • A novel humidifier design was demonstrated with an efficiency reached 98%. [ABSTRACT FROM AUTHOR]

An experimental and theoretical investigation for salt water desalination using tubular direct contact membrane distillation is introduced. The effect of operating and geometric parameters on the unit performance was studied. These parameters include feed water inlet temperature, feed water flow rate, salt concentration, cooling water temperature and membrane inner diameter and length. System thermal efficiency and gain output ratio (GOR) are also evaluated. The investigated parameters were set as follows: 70 °C for inlet feed water temperature, 15–20 L/min for feed water flow rate, 0–40 g Nacl/L water for feed water salt concentration, 20–56 °C for the inlet cooling water temperature, and 15–20 L/min for cooling water flow rate. Maximum productivity, daily efficiency, and Gain output ratio (GOR) of the system reached 40.587 kg/day, 60.06% and 0.624 respectively. Finally, a good agreement has been found between the present numerical data and experimental results. [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) is considered a promising technology that is expected to compete with reverse osmosis (RO) for water desalination. The superiority of MD is mainly due to its ability to treat extremely high salinity water where RO is not feasible. In addition, the problem of accumulation of mycobacteria associated with RO does not exist in MD that operates at temperature as high as 90 °C. This review focuses on the types of solar collectors used to provide the temperature difference needed for MD operation. Comparisons between different types of MD systems powered by solar energy based on their operating temperature, membrane characteristics and type of solar collector is offered together with their advantages and disadvantages as well as relevant industrial applications. Comparison between MD and RO technologies revealed that the RO driven by photovoltaic energy source is considered the best approach for seawater water desalination because it not only achieves the highest daily productivity per meter square of solar field but also has the lowest operating cost. Nevertheless, the MD powered by solar energy is considered a promising technology for treatment of extremely saline water. It is also recommended to integrate MD with RO desalination system to achieve higher water recovery and reduce the overall environmental footprint. • Membrane distillation driven by solar energy is reviewed in detail. • PV-RO achieves the highest daily productivity and the lowest operating cost. • Solar-powered MD is a promising technology for treatment of extremely saline water. • HDH showed also a promising performance for treatment of extremely saline water. [ABSTRACT FROM AUTHOR]

Purifying water using solar energy is a suitable green technique for rejecting salts from saline water. Solar stills are famous and simple devices for sea water desalination but their productivity from freshwater is limited. Various novel techniques were advanced and established to increase the solar still output yield. In the current work, experimental studies with modifications on the ordinary solar still have been conducted to investigate the performance of the new erected solar still. A hybrid solar distillation system comprising of corrugated and wick absorbers of solar stills is integrated with an external condenser to examine their performance. The first solar still is a base traditional type (CSS), while the other one is a corrugated wick still (CrWSS). The performance of CrWSS with internal reflectors, integrated with external condenser and using different types of nanomaterials is investigated and compared with the conventional still. The two types of solar stills are subjected to the same metallurgical conditions. The influence of saline water depth (1, 2, and 3 cm) on CrWSS performance was also investigated. Results showed that integrating an external condenser, with corrugated wick still, with reflectors improves the productivity of the modified solar still. Also; the yield of CrWSS with reflectors when providing a vacuum was enhanced to about 180% higher than the CSS. The productivity of the system is enhanced when using cuprous and aluminum oxides nano particles by an approximate percentages of 285.10% and 254.88% respectively. [ABSTRACT FROM AUTHOR]

The aim of this paper is to introduce a procedure for simulating the absorbed solar radiation and heat transfer process in water-in-glass evacuated tube solar collectors. The procedure is developed to calculate the daily utilized solar energy and outlet collector temperature for different tilt angles, collector azimuth angles and geometric parameters without requirement for any experimental factor determination. Total absorbed solar radiation is evaluated by integrating the flat-plate solar collector performance equations over the tube circumference taking into account the shading of the adjacent tubes and variance of transmissivity–absorptivity product with the incidence angle of radiation. The heat transfer into the collector fluid is evaluated by subtracting the heat loss from the total absorbed solar radiation. Comparison between calculated and measured tank temperature shows a good agreement between them under different heating loads. Performance of solar collector at different tilt angles, collector Azimuth angles, tubes spacing and collector mass flow rate is investigated theoretically. In Egypt (30° Latitude angle), the results show that 10°, 30° and 45° are the optimum solar collector tilt angles during the summer, vernal and autumnal equinox and winter operation respectively. Also, the utilized solar energy increases about 2.8% when the mass flow rate increases 100%, and the solar collector with south-facing has the best performance except for vertical tube solar collector. The simulation results also show that solar collector with wide tube spacing reduce the shading effect and hence increase the absorbed radiation. The final tank temperature as a function of collector's mass flow rate for three different days; 21 March, 21 June and 21 December is also investigated. The total incidence radiation, absorbed solar radiation and utilized heat per tube are presented for the three optimum tilt angles 10°, 30° and 45°. Efficiency curve of water-in-glass evacuated tube collector is also set into comparison with flat plate solar collector and salt gradient solar pond. [ABSTRACT FROM AUTHOR]

Solar still is widely used in solar desalination processes. But the productivity of the solar still is very low. To enhance the productivity of the single basin solar still many research works is being carried out up till now. The various factors affecting the productivity of solar still are solar intensity, wind velocity, ambient temperature, water–glass temperature difference, free surface area of water, absorber plate area, temperature of inlet water, glass angle and depth of water. The solar intensity, wind velocity, ambient temperature cannot be controlled, as they are metrological parameters. Whereas, the remaining parameters can be varied to enhance the productivity of the solar stills. Depth of water in the solar still inversely affects the productivity of the solar still. Maintaining minimum depth in the solar still is very difficult. For maintaining minimum depth, wicks, plastic water purifier and stepped solar still were used. Investigations indicated that a reduction of the brine depth in the still improves the productivity, mainly due to the higher basin temperature. So that stepped solar stills can increase the distillate productivity about conventional solar stills, many reports studied the performance of stepped solar still. In this review, we are attempting to study the present status of different designs of stepped solar stills. [ABSTRACT FROM AUTHOR]

In this paper, performance of a proposed desalination system based on air humidification–dehumidification (HDH) is investigated theoretically and experimentally. To evaluate the performance and productivity of the proposed solar humidification–dehumidification desalination unit, a theoretical simulation model is developed in which the energy equations of each component are considered. Productivity of the proposed system at different operating times during the day is calculated in two periods. First one starts at 9 am and ends at 17 pm, while the second starts after preheating before entering the humidifier at 13 pm to 17 pm. The results show that the highest fresh water productivity is found to be in the second period. A comparison between experimental and theoretical results shows a good agreement and gives evidence that the proposed model is valid to be used under different boundary conditions. The results also show that when the system operates 4 h in a day with preheating before it gives higher productivity of about 22 L/day (11 L/day·m 2 of collector) as a result of stored energy in the system since sunrise. The total cost per 1 l for the unit is 0.0578$. [ABSTRACT FROM AUTHOR]

Highlights: [•] Development of a mathematical model for predicting the performance of solar energy assisted hybrid air conditioning system. [•] The model uses a one-rotor six-stage rotary silica gel desiccant wheel. [•] Theoretical model results are in good agreement with experimental data. [•] The influences of main operating parameters on optimal rotational speed are discussed. [•] A life cycle cost analysis of the proposed system has been investigated. [Copyright &y& Elsevier]

Highlights: [•] Stepped solar still with internal and external reflectors have been investigated. [•] The productivity of the modified stepped solar still is higher than conventional by 103%. [•] The productivity of stepped still with external mirror is higher than that for conventional still by 88%. [Copyright &y& Elsevier]

Highlights: [•] The desiccant wheels used honeycombed silica gel six-stage rotary desiccant cooling system was studied. [•] The mathematical model has been validated with the experimental data. [•] The optimal rotation speed increases with increasing the inlet temperature of the regeneration air. [Copyright &y& Elsevier]

Abstract: This work deals with comparison among different configurations of the hybrid solar powered desalination system. A hybrid desalination system based on air humidification and dehumidification–single stage flashing (HDH–SSF) has been investigated for different configurations. The main effective arrangement parameters and operating conditions that give minimum water cost and maximum performance are shown. The characteristics of this system in different layouts and working conditions are studied in order to evaluate four main parameters; water cost, water production, thermal performance and environmental impacts. Four configurations are analyzed for HDH–SSF desalination system including the conventional system, which is formed by HDH and SSF unit in standalone layout in addition to three different configurations of hybrid and standalone layouts. The present study covered one year of system operation, in summer and winter for typical climate conditions of the Tanta, Egypt. The most important parameters for the proposed system performance were the heat recovery by mixing tank and air preheating. The hybrid HDH–SSF with solar air heater resulted as the best economical configuration with daily water production up to 96l in August and a production cost of 12.53$/m3. The efficiency of the system is measured by the gained output ratio (GOR) with day time. The standalone HDH–SSF with heat recovery resulted as the best performing one with gained output ratio (GOR) about 10.2. [Copyright &y& Elsevier]

Drinking water of acceptable quality has become a scarce commodity. The standard high-capacity desalination methods such as multi-stage flash evaporation and multi-effect evaporation, vapour compression and reverse osmosis are reliable in the range of about 100–500,000 m3/day fresh-water productions. However, the wide-scale implementations of these methods face numerous technological, economic and political barriers and these methods are not used in decentralised regions with a poor infrastructure due to their permanent need of qualified maintenance and electricity supply. In this paper, various low-capacity solar thermal desalination systems, with fresh-water output production in the range of 10–150 l/day for the use in rural areas, are reviewed and classified based on five technological aspects such as the development of the technology of the systems, the applicability of high-capacity thermal desalination technologies, the enhancement of solar heat collectors, the hybridisation of thermal desalination technologies and heat recovery processes. Most of the reviewed systems are in the research stage and have not cleared economic feasibility such as the price per cubic metre of water that may stimulate the decision-maker to direct these studies into the actual commercial applications to find a solution to the water scarcity problem in isolated and remote areas. Although many of the developed systems have several novel and valuable features, more efforts are required for further investigating more efficient, economic and applicable solar energy-driven low-capacity desalination systems. [ABSTRACT FROM PUBLISHER]

Abstract: A solar powered air conditioning system using liquid desiccant is proposed. A solar air heater containing a porous material is used for regeneration purpose in the proposed system. The honeycomb desiccant rotary wheel is constructed from iron wire and clothes layer impregnated with calcium chloride solution, in honeycomb form, is utilized for the regeneration and absorption processes. The effect of airflow rate and solar radiation intensity on the system regeneration and absorption processes are studied. The obtained results show that the system is highly effective in the regeneration process. An empirical equation to calculate the removed moisture as a function of air flow rate at solar noon is obtained. Also empirical equation for wheel effectiveness as a function of air flow rate for regeneration and absorption process was obtained. [Copyright &y& Elsevier]

In open cycle liquid desiccant air conditioning, the solar collector regenerator is one of the effective ways of regenerating liquid solution. In this work, the regeneration of liquid solution using cross flow of air stream with flowing film of desiccant on the surface of a solar collector/regenerator has been investigated. To evaluate the effect of cross flow of air stream on the performance of the unit, two identical units are constructed and tested in the same conditions of operation. One of the two units was augmented with air blower. The absorber plate is a black cloth layer. The forced air stream, which flows across the absorber removes the moisture from the liquid solution. The regeneration in the other collector/regenerator unit is free. The results show enhancement of regeneration efficiency for the forced cross flow compared with the free regeneration. The effect of concentration and flow rate on the performance is discussed. Two relations for regeneration efficiency as a function of concentration for the two units are introduced. [Copyright &y& Elsevier]

• A new PV-powered hybrid HDH-RO desalination system was theoretically assessed. • Thermal energy recovery unit and preheating solar collectors were involved. • Five coupled models were driven, solved, and validated. • As result, the system is feasible for high freshwater production with low power consumption. • Productivity (192–200 L/h), and specific power consumption (1.22–1.24 kWh/m3) were achieved. Recently, constructing a high productive desalination unit with low power consumption has been a challenge. Along with that, this study aimed to simulate a new hybrid desalination unit merging two common techniques of high freshwater production: humidification-dehumidification (HDH), and reverse osmosis (RO). For low power consumption, the hybrid HDH-RO unit was powered with a photovoltaic (PV) systems. The system was provided with thermal energy recovery (TER) units, double-pass solar air collectors (SACs), and evacuated tube solar water collectors (SWCs). The TER units were parallel connected to the backside of PV panels for dual function: enhancing the PV conversion performance by cooling and preheating the seawater before entering the SWC. Both SAC and SWC were proposed to improve the evaporation rate inside the humidifier of the HDH unit. For a comprehensive analysis of the HDH-RO system, five coupled theoretical models were derived and solved, which all were validated by previous experimental data from the literature. All results confirmed that the proposed system can be a good choice for producing freshwater with low power consumption. The maximum hourly freshwater production of the new hybrid HDH-RO desalination system varied between 192 and 200 L, with a water recovery ratio ranged between 48 and 49.8%. Also, its specific power consumption (SPC) ranged between 1.22 and 1.24 kWh/m3, with an average saving a range between 14.7 and 65% compared to previous techniques of RO desalination system. [ABSTRACT FROM AUTHOR]

The ratio between surface area to volume is higher in spherical distillers than traditional single slope distillers. To utilize this advantage, the study measures hemispherical distillers performance. Iron fins have been employed at different lengths and spacing in absorber plate to increase absorption area and transmit heat from hot basin plate to saline water. Three configurations have been tested under same operating conditions. First, the conventional hemispherical distiller without fins representing the reference case (CHSS). Second, the modified hemispherical distiller with fins set at 5 cm spacing (MHSS-IF5). Third, the modified hemispherical distiller with fins set at 7 cm (MHSS-IF7). Fins diameter is constant at 1.2 cm with tested length of 3, 2 and 1 cm starting from the basin absorber plate. Basin salt water is fixed at 3 cm (maximum fin length) during experiments. Results prove that fin utilization is important in performance enhancement. However, fin length effect on performance depends on spacing due to shading effect in distillers. Consequently, the fins utilization improves distiller productivity up to 56.73% with best configuration of MHSS-IF7 with 2 cm fin length and 7 cm spacing. The fins utilization is not costly in the hemispherical distiller with positive enhancement contribution leads to minimum cost per liter of produced water. • Fins utilization in hemispherical distilleris experimentally investigated. • Best configuration is observed at 2 cm fin length and 7 cm‏ fin spacing. ‏. • The fins utilization improves distiller productivity up to 56.73%. [ABSTRACT FROM AUTHOR]

• Investigation of a solar desalination humidification and dehumidification system was introduced. • Five modules of ultrasonic humidifier were used to increase the specific humidity of the ambient air. • The maximum achieved daily water productivity was 44.8 kg/day. • The ultrasonic humidifier improves the daily water productivity. An experimental investigation on the solar system for water desalination was conducted according to the methodology of humidification-dehumidification. Tests have been properly designed and constructed to efficiently assess the productivity of fresh water during the three summer months under local weather conditions of Alexandria, Egypt. The heated air is humidified through two sequent stages, the primary stage is achieved through employing a heated water spatter from the evacuated solar collector. The Further stage is employing an ultrasonic technique for its highly efficient humidification rate. The findings of fresh water output rate is affected by two main parameters; firstly the mass flow rates of both air and water spray, secondly solar radiation. Furthermore, an investigation of heated water spray flow rate over the total flow rate at four values of 0.175, 0.2, 0.25 and 0.3were done respectively. The maximum amount of daily productivity reaches to 44.8 kg/day with mass flow rate of 0.46 kg/s for air, while hot water spray ratio of 0.3. The ultrasonic humidifier improves the daily productivity by 9.3% at 0.24 kg/s and 14.6% at the maximum value of the air mass flow rate 0.46 kg/s. Economic analysis showed that the fresh water cost is about 0.0144 USD/L. [ABSTRACT FROM AUTHOR]

• Effect of solar reheating technology on performance of hybrid system was experimentally studied. • Hybrid system consists from desiccant air conditioner coupled humidification-dehumidification unit. • Coefficient of performance and freshwater production reached 1.11 and 44.08 l/day, respectively. • Improvement in freshwater production for using the solar reheating technology reached 38.96%. • Improvement in gain output ratio for using the solar reheating technology reached 50.35%. The present experimental study aims to enhance a performance of hybrid system of desiccant air conditioner coupled humidification-dehumidification desalination unit using solar reheating technology. To investigate this idea, the regeneration air leaving from desiccant air conditioner was reheated using the solar energy before entering the humidifier of desalination unit. The solar reheating technology aims to increase the ability of the regeneration air to carry the water vapor inside the humidifier and thus increase the freshwater productivity of humidification-dehumidification desalination unit. To obtain the effect of solar reheating technology on the performance of hybrid system, two configurations of the present hybrid system was designed, formed and tested under the weather conditions of Egypt. The first configuration is the desiccant air conditioner coupled with humidification-dehumidification desalination unit; the second configuration is the desiccant air conditioner coupled with humidification-dehumidification desalination unit with solar-reheating technology. The experimental results show that; (i) the coefficient of performance of the air conditioner varying between 0.48–1.11, 0.33–0.61, 0.23–0.42, and 0.18–0.31, for the rate of regeneration air 60, 120, 180, and 240 m3/h, respectively; (ii) the enhancement in accumulated freshwater production for using solar reheating technology in the second configuration reached 26.5, 38.96, 13.16, and 11.31%, as compared to the first configuration for the rate of regeneration air 60, 120, 180, and 240 m3/h, respectively; (iii) the improvement in gain output ratio for using solar reheating technology in the second configuration reached 42.5, 50.35, 22.1, and 18.85%, as compared to the first configuration for the rate of regeneration air 60, 120, 180, and 240 m3/h, respectively. [ABSTRACT FROM AUTHOR]

The demand for water and electricity is gradually increasing throughout the years due to the modern lifestyle of humans to complete their daily activities. To make sustainable water and to produce electricity, the proposed experiment was done. In this, hybrid PV/T active solar still was designed and fabricated in which a solar PV powered Peltier system was incorporated. The Peltier used in this still helps in the enhancement of the distilled water production during both evaporation and condensation processes. Various investigations were made on the proposed active hybrid PV/T system to claim this as the best and it was succeeded. Finally, the proposed active hybrid solar PV/T still produces about 30% higher efficiency than the conventional passive still and also resulted in 38% improved efficiency than the actual solar PV system. [ABSTRACT FROM AUTHOR]

Present work is an effort to study the performance of a PV panel integrated solar still to generate power and to do desalination process to meet the water and power scarcity issues. The system performance is experimentally investigated from different aspects such as still productivity, still efficiency, PV panel power production, PV panel efficiency, and exergy efficiency. Results show that the maximum distillate output of 7.3 kg was obtained when inclined solar panel basin solar still with the sidewall and bottom insulation. The freshwater production from inclined solar panel basin solar still with the sidewall and bottom insulation, inclined solar panel basin solar still with Sidewall insulation and inclined solar panel basin solar still without any insulation was 7.3 kg, 4.4 kg and 3.7 kg respectively. The daily energy efficiency and exergy efficiency of inclined solar panel basin solar still with the sidewall and bottom insulation are higher compared to other cases. The daily efficiency of 34.5%, 38.3% and 71.2% and exergy efficiency of 1.3%, 2.3% and 4.5% was recorded for inclined solar panel basin solar still without any insulation, inclined solar panel basin solar still with the sidewall insulation and inclined solar panel basin solar still with sidewall and bottom insulation respectively. [ABSTRACT FROM AUTHOR]

In the present work, a thermo-economic performance of the modified hemispherical solar still (MHSS) was studied and compared to traditional hemispherical solar still (THSS). The modulations accounted for two additives, namely: paraffin wax as phase change materials (PCM), and copper oxide (CuO) nanoparticles. Three cases of MHSS were investigated and compared to THSS: (0.3 wt%) CuO nanomaterials were immersed in the basin water, implementing PCM container below the basin, and combining PCM container below the basin plus mixing CuO nanoparticles in the basin water. The basin water depth in all stills was set at 1.0 cm in all cases. Moreover, the thermo-economic performance of the four studied cases was compared and evaluated by determining the freshwater productivity, the daily energy efficiency, and the freshwater cost. Experiments have been carried out on the proposed hemispherical distillers under hot climatic conditions of El-Oued (33°27′N, 7°11′E), Algeria. The results show that the single utilization of CuO/water nanofluid and pure PCM improved productivity by 60.41% and 29.17%, respectively, compared to THSS. While, the dual usage of PCM and CuO/water nanofluid further enhanced the productivity by up to 80.20%, relative to THSS. Moreover, the daily energy efficiencies of the hemispherical distillers under the different studied cases (THSS, MHSS/PCM, MHSS/CuO-water nanofluid, and MHSS/PCM + CuO-water nanofluid) were found to be 35.52%, 45.45%, 56.46%, and 63.61%), respectively. The economic feasibility of these modifications presented that the dual usage of PCM and CuO/water nanofluid is more effective as it reduces the cost of freshwater production by 75% compared to THSS. In the third distiller (Modified hemispherical solar still with 0.3 wt% CuO/water nanofluid (MHSS-CuO/water NF)), the modified was done by adding (0.3 wt%) copper oxide (CuO) nanomaterials to the basin water, to improve the thermal properties of nanofluid and increase the intensity of the absorbed solar energy. In the fourth distiller (Modified hemispherical solar still with paraffin wax as phase change materials and 0.3 wt% CuO/water nanofluid (MHSS-PCM + CuO/water NF)), it was designed and constructed a circular galvanized steel container 1 mm thick, 340 mm diameter, and edge height 40 mm, coated with the black pained. This container was placed inside the wooden basin of the hemispherical solar still. A gap of 20 mm thickness was maintained between the container and the wooden basin on the bottom side and sidewall. 2.0 kg of paraffin wax as phase change materials was placed in the gap between the container and the wooden basin, to store the solar energy in the periods of higher solar rays and recovery it in the periods of low solar rays and after sunset. Moreover, in this modification copper oxide (CuO) nanomaterials were also added to the basin seawater with a concentration of 0.3 wt%, to improve the thermal properties of saline water and increase the intensity of absorbed solar energy, and improve the rates of heat transfer. • Dual usage of PCM and CuO nanofluid has great influence on hemispherical distiller performance. • Thermo-economic performance of the modified hemispherical solar still was studied. • Dual usage of PCM and CuO/water nanofluid enhanced the productivity by 80.20%. • Dual usage of PCM and CuO/water nanofluid reduces the freshwater cost by 90%. • Daily efficiency of MHSS with dual usage of PCM and CuO/water nanofluid reached 63.61%. [ABSTRACT FROM AUTHOR]

Abstract: An experimental study was conducted to improve the productivity of basin solar stills by increasing the surface area of absorber (base of still) and rate of heat transfer between saline water and absorber. In view of this, three solar stills are designed and fabricated in order to study the performance of each still. The first one is a conventional type and the second is a finned still while the third one is corrugated still. The performance of the finned and corrugated solar stills is tested and compared with conventional still under the same climate conditions. The performance of different solar sills were tested under two cases; stills at the same water depth (50mm) and stills at the same quantity of saline water (30 and 50l). The results indicate that the productivity of finned and corrugated solar stills is higher than that for conventional still. Also it is found that at quantity of saline water 30l the productivity increased, when finned solar still and corrugated solar still are used approximately by 40% and 21% respectively. In this case the daily efficiency and estimated cost of 1l of distillate for finned, corrugated and conventional solar stills are approximately 47.5%–0.041 $, 41%–0.047 $ and 35%–0.049 $ respectively. [Copyright &y& Elsevier]

• An intensive review of the recent solar-powered RO desalination systems is conducted. • Brine disposal methods are compared to show the most applicable for inland plants. • Separate and hybrid preheating techniques are classified and discussed. • Different applicability challenges and limitations are highlighted. Globally, reverse osmosis desalination systems are widely utilized as they have the cheapest freshwater production cost. On the contrary, reverse osmosis systems have high specific energy consumption and membrane fouling that requires continuous chemical cleaning. Additionally, the plants' performance and their applicability can be stated via different terms: specific energy consumption, freshwater cost, thermal efficiencies, configurations, water recovery factors, and water quality. Therefore, many investigations have been conducted to enrich these indicators. Accordingly, the current review aimed to comprehensively merge most of these studies to give a complete picture of the recent developments of reverse osmosis plants considering all the aforementioned parameters. On the one hand, the current survey focused on solar-based reverse osmosis plants, which were established to decrease the specific energy consumption using photovoltaic or solar thermal power plants; especially, the organic Rankine cycle. Besides, various preheating techniques and relevant works were presented. The preheating boosts the plants' thermo-economic performance, and yield as the power consumption and productivity proportionally vary with the feedwater temperature. The preheating can be conducted by recovered heat from other systems, such as photovoltaic cooling unit, humidification-dehumidification process, organic Rankine cycle, and hybrid systems. Finally, the brine disposal methods were introduced, discussed, and compared to help in identifying the most appropriate economic technique, especially for the inland desalination plants. It is proposed that this review can help in the research continuity in the desalination field, especially reverse osmosis plants. [ABSTRACT FROM AUTHOR]

Thermal energy storage plays a vital role to solve the problems related to the intermittent nature of solar energy. Phase change materials (PCMs) have shown promising applications in different thermal energy storage systems. Cascaded Thermal Storage (CTS) PCMs (multiple PCMs in a descending order of their melting temperatures), added new advantages to the applications of PCMs in thermal energy storage systems. Solar water collectors (SWCs) that utilize PCMs have been used to achieve economic and environmental benefits via substituting large-scale demand of energy. This literature review focuses on the different developments of PCMs and CTSPCMs and their implementation in SWC storage tanks. The novel and most recent developments of PCMs and CTSPCMs utilized in solar storage tanks with SWCs, such as, multi-storage tank with cascaded PCM, packed bed storage units, different configurations of heat exchanger storage units, and other innovative storage tank designs, are reviewed and discussed. Furthermore, the existing studies that evaluated the PCM heat transfer improvement, thermal storage performance, thermodynamic optimization, and applications of cascaded thermal storage systems are also reviewed. The reviewed results in this work showed that the CTSPCM system can promote a significant improvement in the PCM heat transfer and stored rates of entransy, energy, and exergy, as well as lead to an increased storage energy and exergy efficiencies compared to the single stage PCM system. It is also revealed that: the multi-tank integrated with cascaded PCMs system is the best amongst the studied PCM storage tank systems within SWCs, for augmenting the storage capacity and improving the overall thermal efficiency of the water heating system. A noteworthy observations, important proportionalities, and future trends are also discussed for each technique. [ABSTRACT FROM AUTHOR]

Highlights • The nanofluids used as heat transfer fluid within the solar collectors are reviewed. • The effect of type, nanoparticle concentration, and mass flow rate of the nanofluid. • on the thermal efficiency is discussed. • Multi-walled carbon nanotubes/water nanofluid is the best among all the studied. • nanofluids. • Copper oxide/water nanofluid is the best among the studied metal oxides. Abstract Exploitation of solar energy is one of the most significant solutions for facing the current energy management dangers. Flat plate solar collector (FPSC) is one of the most important applications of solar energy in different domestic applications. The use of nanofluids in FPSCs, due to their superior thermo-physical properties, makes it an effective way to enhance the performance of FPSCs. This paper sequentially reviews the studies carried on metal, metal oxides, semiconductor crystalized oxides, and carbon based nanofluids used as heat transfer fluid (HTF) within FPSCs. Various parameters that affect thermal performance of the FPSC such as type of nanoparticle, nanoparticle concentration, nanoparticle size, and mass flow rate of the nanofluid are extensively analyzed in this review. The studies examine different types of single nanofluids or hybrid nanofluids with the FPSC at the same operating conditions are also discussed. Based on the results reviewed in this work, it is revealed that a significant improvement in energy and exergy efficiencies of the FPSC have been obtained by using carbon based nanofluids compared to metal oxides nanofluids under the same conditions. It is also found that the copper oxide nanofluid is the best amongst the metal oxides nanofluids as it improves the efficiency by 6.3–37.3% compared to conventional fluids when it is used with concentration varied from 0.025 to 2%, and mass flow rate ranges from 1 to 8.8 kg/min. A noteworthy observations, proportionalities, and future trends for each nanostructure type are also discussed with detailed and comparative approach. [ABSTRACT FROM AUTHOR]

Abstract The development of different solar energy (SE) systems becomes one of the most important solutions to the problem of the rapid increase in energy demand. This may be achieved by optimizing the performance of solar-based devices under some operating conditions. Intelligent system-based techniques are used to optimize the performance of such systems. In present review, an attempt has been made to scrutinize the applications of artificial neural network (ANN) as an intelligent system-based method for optimizing and the prediction of different SE devices' performance, like solar collectors, solar assisted heat pumps, solar air and water heaters, photovoltaic/thermal (PV/T) systems, solar stills, solar cookers, and solar dryers. The commonly used artificial neural network types and architectures in literature, such as multilayer perceptron neural network, a neural network using wavelet transform, Elman neural network, and radial basis function, are also briefly discussed. Different statistical criteria that used to assess the performance of artificial neural network in modeling SE systems have been introduced. Previous studies have reported that artificial neural network is a useful technique to predict and optimize the performance of different solar energy devices. Important conclusions and suggestions for future research are also presented. [ABSTRACT FROM AUTHOR]

Highlights • Conducted a theoretical analysis of solar still thermal performance with micro/nano particles. • Evaluated the energy and exergy efficiencies for modified and conventional solar still. • Determined the destructions exergy for different components of solar still. • Estimated the heat transfer coefficients of solar still with and without micro/nano particles. • Estimated the costs of solar still with and without micro/nano particles. Abstract In this paper, a theoretical comparative study between modified solar stills (MSSs) and classical solar still (CSS) was carried out, based on the productivity and the thermal properties. The MSSs contain brackish water mixed with either graphite or copper oxide (CuO) micro/nano particles. Cost estimations of solar still desalination by using micro/nano particles was estimated. exergy destruction in various components of the solar still (SS) were calculated, analyzed and discussed. The exergy loss during the day time comprises the exergy destruction in the main components of the SS like basin plate, brine water, glazier plate and insulation material. The hourly convective, evaporative and radiative heat transfer coefficients (HTCs) with and without micro/nano particles were determined. The exergy destruction in various components of the SS have been analyzed and a solution was suggested. Results revealed that the exergy of evaporation, energy efficiency and exergy efficiency of MSSs were higher than that of the classical one. The daytime energy efficiencies of MSSs with graphite and CuO were 41.18% and 38.61%, respectively, but for the CSS was only 29.17%. The diurnal productivity of the MSSs was increased by 41.18% and 32.35% for graphite and CuO, respectively, compared with CSS. Moreover, the diurnal exergy efficiencies of MSSs were 4.32% and 3.78% for graphite and CuO respectively, while exergy efficiency for CSS was 2.63%. Furthermore, the costs of water production were found to be approximately 0.20, 0.21 and 0.24 RMB/L (1 RMB = 0.15 US $) when using MSS with CuO, MSS with graphite and CSS, respectively. [ABSTRACT FROM AUTHOR]

In this study, an evaluation on the efficiency of an inclined copper-stepped solar still was performed through theoretical and experiment. Inclined trays were used to increase the efficiency of a system. The theoretical calculations and the experiment were conducted by the Faculty of Engineering and Built Environment, UKM, Bandar Baru Bangi, Selangor. Experimental data was utilized to test the theoretical model and the results show good acceptance between the experimental and theoretical data. The convective, evaporative, and radiative heat transfer coefficients and the water productivity and efficiency were calculated for each hour. The findings revealed that the maximum hourly productivity in the inclined copper-stepped solar still for the theoretical and experimental were 474 mL/m 2 h and 605 mL/m 2 h. Additionally, the daily efficiency varied between 28.33 and 29.5% for the inclined copper-stepped solar still from September to December 2016. [ABSTRACT FROM AUTHOR]

By airing wick materials, i.e. airing evaporation setup (AES), the solar evaporation rate is much higher than that of the current nanofluidic evaporation setup (NES) and floating evaporation setup (FES). • A simple but efficient airing evaporation setup (AES) was proposed. • No insulation material is required in AES. • The total evaporation rate of AES is about 20% higher than floating evaporation setup. • AES is mechanical flexible, hence very suitable for portable systems. • AES inspires the design of multifunctional textile for solar energy harvesting. Solar evaporation is important for many applications such as desalination, power generation and industrial drying. Recently, some studies on evaporation reported obtaining high energy efficiency and evaporation rate, which are based on floating evaporation setup (FES) with nanomaterials. Here, a new cheap and simple setup is proposed, named as airing evaporation setup (AES). Compared to FES, there are four advantages of AES: a better thermal design, a higher energy efficiency, a higher material utilization ratio, and multi-function. It shows that the energy efficiency of AES reaches up to 87% under 1 kW/m2 of solar irradiation, which is 14% higher than that of FES. Meanwhile, the total evaporation rate of AES is about 20% higher than that of FES. The theoretical analysis reveals that the main reason for a better performance of AES is the increasing evaporation area. More interestingly, AES could be used for designing portable systems due to its simplicity and flexibility. Furthermore, it is shown that AES and the corresponding wick material can be used in solar desalination, textile quick-drying and warm-keeping. [ABSTRACT FROM AUTHOR]