Cost Of Fresh Water Production Research Articles

Augmenting thermal performance in tubular solar stills: A multifaceted strategy with wick cords, integrated baffles, reflectors, and nano-PCM

This study investigates the enhancement of freshwater production using a modified cords wick tubular solar still (CWTSS) compared to a traditional tubular solar still (TSS). The CWTSS design increased freshwater yield by 102 % over the baseline TSS. Also, the impact of using baffles (CWTSS-B) was tested. Incorporating reflectors into the CWTSS (CWTSS-B-R) further improved performance, achieving a 201 % increase in production with reflectors and 160 % without reflectors, highlighting the significant role of reflectors in solar energy capture and distillation efficiency. Various wick cord numbers (12, 22, 32, and 42) were tested to identify the optimal configuration. The use of nanoparticle-enhanced Phase Change Material (PCM) in the CWTSS (CWTSS-PCM) resulted in a 240 % production increase compared to the TSS, demonstrating the effectiveness of PCM in thermal energy storage and management. The most significant improvement was observed in the CWTSS-fan configuration, which employed a fan and an external condenser, leading to a 256 % increase in water production, reaching 15,300 mL/m2 compared to 4300 mL/m2 for the TSS. The modified design's freshwater production cost was $0.01/L, a 50 % reduction from the conventional design's cost of $0.02/L.

Experimental investigation of a sun tracking concentrated solar still with economic analysis

The current paper evaluated experimentally an innovative sun tracking concentrated solar still under Egyptian climatic conditions during the summer of 2022. The proposed system consists of a 120-cm-diameter parabolic reflector mirror that tracks the sun using a dual axis tracking system, a cylindrical solar still with a volume of 3.7 L positioned in its focal point, and a concentration ratio of 12.5. The performance of the concentrated solar still was investigated in the context of two critical parameters. First, three feed water salinity (17, 27, 37) ppt samples were evaluated, followed by four percentages of saline water filling ratio (26.5, 39.8, 53.1, 66.3)%. Increasing the salinity of the feed water had no effect on solar still productivity, but increasing the saline water filling ratio did. The daily cumulative productivity of the system was 6 kg/m2 with an optimal filling ratio of 53.1%, a daily efficiency of 42.88%, and an average cost of freshwater production of 0.0489 $/L. The proposed system also had the highest instantaneous efficiency of 61.77% and the highest distilled water productivity rate of 0.941 kg/h m2.

Evaluation of mechanical vapor recompression and easy multi-effect desalination systems in different climate conditions-sensitivity and 7E analysis

Evaporative desalination systems, such as Multi-Effect Desalination (MED) and Mechanical Vapor Recompression (MVR), play important roles in addressing this challenge. Although large-scale desalination systems possess limitations in catering to the water demands of remote regions and islands and entail the cost of water transportation to residential areas, it is imperative to concentrate on studying the feasibility of employing centralized evaporative water production systems. Firstly, in this study, the initial focus is on conducting energy and exergy analyses of MVR and Easy MED systems, with a goal of enhancing knowledge about the energy consumption, exergy destruction and exergetic efficiency of these systems. Secondly, an economic analysis is undertaken to assess the feasibility of deploying these systems in various global regions. The analysis takes into account different geographical and techno-economic conditions, such as sea water temperature, interest rates, and electricity costs. This investigation also aims to explore variations in Annual Operative Cost (AOC), Total Annual Cost (TAC) and the cost of fresh water across these diverse regions. Thirdly, a sensitivity analysis is performed for the economic assessment of MVR and Easy MED systems. Lastly, exergoeconomic, environmental, enviroeconomic and exergoenvironmental analyses are conducted for both of these systems. The results show that the exergy efficiency of the Easy MED system surpasses that of the MVR, whereby the exergy destruction for Easy MED and MVR are recorded to be 5460 W and 6360 W respectiveyl. In addition to this, the MVR system demonstrated a higher TAC across all cities. The freshwater production cost of the Easy MED system was less expensive than of the MVR system. Perth was the most cost-effective city, with freshwater costs of 6.8 €/m3 and 11.91 €/m3 for MVR and Easy MED systems, respectively. Further to this, sensitivity analysis revealed that both systems are sensitive to fluctuations in electricity costs and seawater temperatures. The MVR system incurred higher fuel, product, and exergy destruction costs. However, the MVR system also exhibited greater environmental friendliness due to its lower emission of pollution gases.

Analysis of heat pump operated two-stage humidification-dehumidification desalination system with subcooler and heat regenerator

The heat pump operated single-stage humidification-dehumidification desalination system, configured with a subcooler and a heat regenerator, has been proven highly effective in improving both freshwater productivity and energy efficiency. To investigate the potential benefits of increasing the number of humidification stages, this paper presents a heat pump operated two-stage humidification-dehumidification desalination system by adding a pre-humidifier. Subcooler and condenser of the heat pump are used as the heat sources of the main humidifier and the pre-humidifier, respectively. Through parametric studies, a comparative analysis is conducted on the thermodynamic and economic performances of both the heat pump operated single-stage system and two-stage system at various operating conditions. The results show that such system modification can greatly improve system performances. Compared to the single-stage system, the maximum freshwater productivity of the two-stage system is 42.89 kg/h, increased by 19.77 %; the peak gain output ratio is 7.93, up by 9.53 %; and the lowest specific electricity consumption is 79.34 kWh/m3, reduced by 15.15 %. Furthermore, the freshwater production cost for the two-stage system, ranging from 7.78 to 13.33 $/m3, is also superior that of the single-stage system, further demonstrating its substantial value in practical product development and market promotion.

Evaluation of two-stage humidification-dehumidification desalination systems operated by a modified heat pump

The humidification-dehumidification desalination system operated by a heat pump is ideal for the decentralized small-scale desalination plant, due to its advantages of low investment and stable freshwater provision. To overcome the heat source limitation of multi-stage humidification-dehumidification system, a modified heat pump with a subcooler is used to operate the two-stage humidification-dehumidification system. With the difference of heated object, two layouts of the heat pump operated two-stage humidification-dehumidification systems are proposed, which are twice water-heated system and twice air-heated system. A parametric study is conducted to analyze the effect of feed seawater temperature and water/air mass flow ratio on the thermodynamic and economic performances of the proposed systems. A performance comparison is also carried out to analyze the difference between water heating and air heating, together with advantages over the reported systems. According to the results, it can be concluded that optimal feed seawater temperature and water/air mass flow ratio exist for the proposed systems. The twice water-heated system outperforms the twice air-heated system with the maximum freshwater productivity and gain output ratio of 34.69 kg/h and 7.69, while the lowest specific electricity consumption and freshwater production cost of 89.18 kWh/m3 and 14.52 $/m3. These results are also superior to those of previously reported HP-HDH systems, fully demonstrating the value of research and development for this novel system and its promising market application prospects.

Sustainable and clean water distillation by parabolic dish collector and different heat absorber and thermal storage materials: An experimental study

In this study, an integrated solar distillation unit with a parabolic dish collector and a spherical solar water distillation unit is designed. The use of parabolic dish collector increases the evaporation rate of the saltwater in the lower chamber (basin) of the spherical distillation unit considerably. The performance of solar water distillation system is investigated for different types of basin material, including copper, zinc, and iron. In the second part, the gravel is used in the copper basin of solar distillation system as the thermal energy storage material. The thermal efficiency, water productivity, exergy efficiency, and freshwater production cost of the integrated solar distillation system with different types of basin materials are studied. The thermal efficiency of the integrated solar distillation system with the copper, zinc, and iron basins was 13.97 %, 10.72 %, and 9.88 %%, respectively. The water productivity of the integrated solar distillation system with copper, zinc, and iron basins was 2.592 kg, 2.27 kg, and 1.825 kg, respectively during 9 h of experiment. The exergy efficiency of the integrated solar distillation system with the copper basin was better than the zinc and iron basins. The gravel can increase the productivity of solar distillation system up to three times in the sunset and night hours.

Assessment of direct contact membrane distillation system driven by parabolic trough collector plant technology for electricity and freshwater production: Feasibility and benchmark under different Moroccan climates

Morocco has experienced several years of drought, conventional water resources were insufficient to meet the needs of the population, which prompted the kingdom to seek other resources to ensure the supply of drinking water to this population. The most suitable solution was the desalination of seawater. In this context, the design and investigation of concentrated solar power (CSP) plant integrated with a desalination unit in Morocco are presented in this paper. The CSP part consists of a parabolic trough technology with a two-tank storage system, integrated with a power block of 111 MWe gross consisting of a conventional Rankine cycle. As for the desalination part, it consists of a Direct Contact Membrane Distillation System (DCMD) based on heat and mass transfer equations, and is solved numerically by MATLAB environment; the model was validated by means of the experimental data. The results show that the large-scale Parabolic Trough Collector (PTC) plants are more competitive in Dakhla -southern Morocco- where the annual energy generation and the capacity factor were estimated to be 493.8 GWh, and 47.6%, respectively. Whereas, the Levelized Cost of Electricity (LCOE) is 10.63 ȼ/kWh. Furthermore, it has been found that in the DCMD system, an increase in the feed water temperature leads to an increase in permeate flux. Besides, freshwater production is highest in winters for Dakhla and Agadir (Atlantic Ocean) and it is highest in summers for Saidia and Al Hoceima (Mediterranean Sea). The lowest freshwater production cost is 0.84$/m3 in Dakhla, followed by 0.98$/m3 in Saidia, with the highest production cost at 1.20$/m3 in Agadir.

Extended experimental investigation of a double-effect active solar still with a paraffin wax, in Owerri, Nigeria

In this work, an experiment-based study of a double-effect, single-slope active solar still (SSASS) is presented. The system comprises an upper and a lower basin incorporated with a paraffin wax acting as a phase change material (PCM). The use of phase change materials is very important due to their high storage density and the isothermal nature of the storage pro-cess. Paraffin wax was selected based on its attractive thermo-physical properties. The thermal behaviours of the system during the diurnal and nocturnal phases in both compartments were explored. Experimental results showed that the upper basin’s yield contributed more to the overall distillate production over a 24-hour cycle while that of the lower basin predominated the diurnal production. Though the PCM served as an energy source during the nocturnal phase, it did not translate to significant improvement in the yield of the lower basin. The heat retention ability of the lower glazing retarded the condensation of the humid air in the lower compartment during the off-sunshine period. Thus, the nocturnal yield of the system was largely driven by the improved temperature difference between the upper saline water and the upper glazing, as well as the stored thermal energy in the saline water mass before sunset. The system achieved a maximum yield of 2,450 ml/day and a yield rate of 232.5 ml/h. A maximum monthly average yield of 1,787 ml/day was realized in May and a minimum of 692 ml/day in July. Nocturnal distillate production accounted for an average of 55% of the total distillate recovered from the still daily. The system achieved an efficiency range of 12.20 - 32.21%. The cost of freshwater production from the system is estimated at 0.0508 $/L with a payback period of 267 days. Thus, this system is economically viable and suitable particularly, for low-income earners.

Energy and exergo-economic analysis of a parallel feed multi-effect system integrated with humidification–dehumidification system for brine recovery

Desalination technologies reject large amounts of brine with significant value back to sea. The concept of hybridization of different desalination technologies has proven that it can be effective in terms of reducing rejected brine and increasing the freshwater production rate as well as reducing the freshwater cost. In this work, brine recovery to improve water production through a simple modified configuration of integrating a multi-effect desalination (MED) system with humidification–dehumidification system (HDH). The rejected brine of the MED system is used as the feed for the HDH system without the need for preheating the rejected brine since it leaves the MED at a suitable temperature for HDH application. The study focuses on investigating the effect of different operating conditions on the increase in system freshwater production rate and recovery ratio as well as the exergetic efficiency. Parameters investigated include steam temperature, feed salinity, number of brine streams, cooling water flow rate, and ambient temperature. An exergo-economic analysis has also been conducted using the cost flow method to evaluate the freshwater production cost for the modified system. Results indicate that the integration of HDH can increase the water production rate by a maximum of 7.82% and produce fresh water at 2.08 $/m3 compared to 2.094 $/m3 when using the standalone system under the same conditions.

Experimental investigations on a sustainable cogeneration system for power and desalination with 4-E analysis

Several research investigations were carried out on the potential integration of solar stills with photovoltaic modules to improve freshwater production and electric output. The current work aims at integrating stepped solar still (SSS) with a bi-directional flow serpentine thermal absorber-based Photovoltaic-Thermal (PVT) module. Near the vernal equinox days, a laboratory-scale experimental facility is designed, developed, and tested in Vellore (12.9165° N, 79.1325° E). The novelty of the proposed system is that it effectively utilizes the waste heat recovered from PVT with a unique thermal absorber for preheating saline water supplied to the SSS. Experiments were carried out on a PVT-SSS system to estimate the electricity and freshwater generation by PVT and SSS for saline water flowrates of 0.3, 0.5, 0.75, and 1.00 LPM. The estimated average electrical efficiency of the PVT panel is 14.84 %, 15.46 %, 14.74 %, and 14.50 %, and the freshwater productivity from SSS is 3460 ml, 2970 ml, 2460 ml, and 1950 ml per square meter. The average thermal efficiency of the proposed PVT-SSS system is 34.5 %, 31.8 %, 20.1 %, and 16.3 %; 49.36 %, 47.30 %, 34.90 %, and 30.83 %, respectively, for the mentioned flow rates. Further, the average exergy efficiency of the system is observed as 18.5 %, 18.7 %, 17.2 %, and 16.6 %, respectively. In addition, the unit cost of freshwater production for various flow rates in USD is estimated as 0.07, 0.08, 0.09, and 0.10, respectively. An environmental analysis was also performed to determine the CO2 emissions and carbon mitigation for the proposed hybrid desalination system. The results are validated with previous literature.

Performance evaluation of a novel humidification-dehumidification desalination system operated by a heat pump

Decentralized and small-scale desalination technologies can effectively address the limitations associated with large-scale desalination systems and contribute to solving the issue of fresh water scarcity. However, low energy efficiency remains a primary obstacle in their widespread application. To tackle this challenge, this paper introduces a novel heat pump humidification-dehumidification desalination system, in which humid air from the dehumidifier enters the heat regenerator and heat pump evaporator in sequence, enabling deep dehumidification. Subsequently, the cold air is reheated by the heat regenerator and subcooler before entering the humidifier. This sequential process can increase not only the energy efficiency of heat pump but also the fresh water productivity. Models are proposed and calculated for the theoretical evaluation of the novel system. Firstly, heat pump design parameters are optimized. Subsequently, performances of the novel system under different operation conditions are compared with those of the conventional system. The results indicate that optimizing heat pump system design parameters can significantly improve system performance. When compared to the conventional system, the novel system exhibits significant improvements. It achieves a maximum fresh water productivity of 39.73kg/h, representing an increase of 12.83%, and a maximum gain output ratio of 6.52, which is 13.39% higher. The lowest fresh water production cost is 9.52 $/m3, also a reduction of 5.15%. Additionally, both the novel and conventional systems possess optimal feed temperature and mass flow rate ratio. At last, the optimal performances of the novel system are compared with the reported results, which further validates the thermodynamic and economic advantages of the novel system.

Experimental study of simultaneous effect of evacuated tube collectors coupled with parabolic reflectors on traditional single slope solar still efficiency

Enhancing the performance characteristics of solar still is considered one of the most significant factors to increase the still efficiency. This research aims to modify the single slope still to enhance efficiency and maximize freshwater productivity. For this purpose, three evacuated tube collectors have been coupled with traditional still to heat up the basin saline water. Also, a parabolic trough reflector has been combined with each evacuated tube collector to increase the amount of solar radiation received. In this work, the performance characteristics and energy analysis of the modified stills were experimentally investigated by considering the effect of traditional still unit only, traditional still unit coupled with an evacuated tube collector, and traditional still unit coupled with both evacuated tube collector and parabolic trough reflectors in combination. The results show that using both modifications simultaneously is more efficient than using each of them separately. According to the results, an increase in productivity of 82.26% when the still coupled with the evacuated tube collectors is used, and 112.57% increase when both modifications are used simultaneously. According to the cost evaluation, using simultaneous mechanisms not only enhances the solar still performance and increase efficiency but also decrease freshwater production cost.

Dual brine concentration for the beneficial use of two concentrate streams from desalination plant - Concept proposal and pilot plant demonstration

A dual brine concentration concept is proposed and proved in a pilot plant demonstration with commercial membranes. To utilize the dissolved ions in seawater (45,000 mg/L) effectively for various applications, a nanofiltration (NF) system is introduced in the upstream of the reverse osmosis (RO) system, and a membrane brine concentration (MBC) system is introduced after RO to concentrate the RO brine to the desired point, i.e., 15 wt% (166,000 mg/L) and higher. In the proposed NF-RO-MBC system two valuable brines are produced: 1) Concentrate 1, which is highly concentrated and purified monovalent ion stream at a TDS of about 170,000 mg/L after HPRO and 2 stage OARO, and 2) Concentrate 2, which has a high concentration of divalent ions, such as 3.41 times the Ca and 5.17 times the Mg concentration compared to those in seawater. Based on the successful pilot demonstration data and performance evaluation of a novel NF membrane and a single OARO module, a commercial-scale NF-RO-MBC system was designed for the capacity of 1 mil. dry ton/year production of NaCl salt in the form of 169,000 mg/L concentrated brine. With the proposed configuration, 65.2 % of the seawater will be recovered as fresh water, 19.3 % will be Concentrate 1, and the remainder 15.5 % will be Concentrate 2. The specific electricity consumption of the NF-RO-MBC system is estimated as 6.90 kWh/t of the fresh water produced, and the techno-economic analysis estimated the production cost of fresh water as 0.57 USD/m3 and that of NaCl brine as 28.87 USD/dry t NaCl.

Part load operation of an integrated solar combined cycle using the brine heater of a MSF desalination unit as a steam condenser

Hot-climate countries, like Egypt, have an energy surplus while suffering water scarcity. Energy surplus causes frequent part load operation of Integrated Solar Combined Cycle (ISCC) power plants. The present work proposes a cycle that combines an ISCC with a Multi Stage Flash (MSF) desalination unit. The brine heater of the MSF desalination unit acts as a steam condenser for the ISCC. The condenser pressure/top brine temperature of the MSF desalination unit controls the ISCC part load operation. A simulation model for an actual ISCC in Kuryamat-Egypt was developed and validated. A validated model for the MSF unit was integrated with the developed ISCC model. The proposed cycle (ISCC-MSF) was simulated under different operating and geometric conditions. The simulation results were used to optimize the MSF desalination unit and achieve a performance ratio of 11.65 and a 7.7% reduction in the stage area. Cost analysis was performed for the unit production cost of fresh water (UPCMSF), where a reduction of UPCMSF to 0.77$/m3 was achieved. Further reduction of UPCMSF down to 0.54$/m3 can be attained by reducing the interest rate from 5% to 1%. Detailed part load performance investigation of the proposed cycle is recommended for future work.

Feasibility of desalination by solar stills for small community scale freshwater demand

Solar stills are conventional desalination systems based on direct solar heating. While their productivity is limited, their simple construction and low maintenance requirements makes them an attractive and feasible option for community-scale desalination. This study shows that low-cost solar stills are capable of producing sufficient freshwater for small disadvantaged communities at costs lower than competing technologies. A variety of solar still materials are investigated showing that the cost of freshwater produced is sensitive to the solar still cost. Inexpensive carbon black particles dispersed in the water are used to increase solar still performance, and a set of low-cost solar still materials are identified from a pool of candidate materials to minimize water production cost by means of optical and energy analyses. In addition, communities with fewer than 10000 residents are identified in the reference region of California to perform an energy analysis to determine freshwater productivity yield and the cost of freshwater production. It is determined that a 10000 m2 solar still could produce freshwater meeting the requirements of small rural communities costing less than $ 7.71 /m3. Attractive investment options are available that could reduce the cost of water produced to less than $ 1.75 /m3. Solar stills were found to be feasible when comparing the cost of freshwater produced with a comparable photovoltaic reverse osmosis system. The proposed methodology can be extrapolated to determine the feasibility of solar still-based desalination systems in other geographical locations. From the results of the analysis, solar stills are proposed for effectively producing low-cost freshwater to increase the accessibility of freshwater in small rural communities.

Experimental study on the effect of the black wick on tubular solar still performance

Solar water desalination is the future alternative to overcome both pollution and water shortage issues. This study describes the effect of a low-cost cotton wick material on the performance of tubular solar still integrated with a parabolic concentrator solar tracking system. Outdoor experimental work was conducted in the real field under July climatic conditions of Ha'il city (995 m above sea level), Saudi Arabia. Results of the tubular solar still with and without the wick were compared to evaluate the achieved improvement of the developed device. Comparative analysis shows a higher performance for the wicked device with a significantly lower freshwater production cost. The use of the black cotton wick increased the device productivity and efficiency by 29.11% and 24.45%, respectively, and lowered water desalination production cost by 40.21%. The device with the wick was able to produce 5.1 L/m 2 day of water desalination with the 40.21% lower cost compared with that of the device without the wick. This productivity can satisfy the basic needs of one person during a day in small and isolated communities.

A Feasibility Study of Utilizing Nuclear Energy for an Existing MED-TVC Desalination Plant

This study aims to investigate the viability of using a nuclear heating reactor to supply energy and replace the used fossil crude oil energy supply of an existing MED-TVC (Multi-Effect Distillation-Thermal-Vapor-Compression) desalination plant located in Saudi Arabia. The MED-TVC, with a 91,200 m3/day capacity, was simulated using Aspen Plus®. The MED-TVC desalination plant was built in a parallel arrangement with oil-fired steam boilers, and it uses Red Sea water with a salinity of about 45,000 ppm. The simulation results of the MED-TVC are in good agreement with the actual data of the existing desalination plant. The heat required to operate the existing MED-TVC was determined to be 169 MW (th). This amount of heat was utilized as an input to DEEP (Desalination Economic Evaluation Program) to evaluate the production cost of fresh water using nuclear energy instead of fossil fuel. An economic comparison between the two energy sources was carried out in this study. The production cost of freshwater was estimated to be USD 1.38/m3 when using a nuclear reactor. In contrast, the estimated production cost was USD 0.95/m3 when using oil-fired boilers at a subsidized oil price of USD 4.4/bbl. The economic analysis has considered the discounted domestic crude oil prices in Saudi Arabia. Nuclear energy is cost-competitive with oil if Saudi Arabia raises the price of domestic crude oil to more than USD 15 per barrel or imposes a carbon tax of at least USD 20 per ton of greenhouse gas emissions.

Evaluation of Solar Energy Powered Seawater Desalination Processes: A Review

Solar energy, amongst all renewable energies, has attracted inexhaustible attention all over the world as a supplier of sustainable energy. The energy requirement of major seawater desalination processes such as multistage flash (MSF), multi-effect distillation (MED) and reverse osmosis (RO) are fulfilled by burning fossil fuels, which impact the environment significantly due to the emission of greenhouse gases. The integration of solar energy systems into seawater desalination processes is an attractive and alternative solution to fossil fuels. This study aims to (i) assess the progress of solar energy systems including concentrated solar power (CSP) and photovoltaic (PV) to power both thermal and membrane seawater desalination processes including MSF, MED, and RO and (ii) evaluate the economic considerations and associated challenges with recommendations for further improvements. Thus, several studies on a different combination of seawater desalination processes of solar energy systems are reviewed and analysed concerning specific energy consumption and freshwater production cost. It is observed that although solar energy systems have the potential of reducing carbon footprint significantly, the cost of water production still favours the use of fossil fuels. Further research and development on solar energy systems are required to make their use in desalination economically viable. Alternatively, the carbon tax on the use of fossil fuels may persuade desalination industries to adopt renewable energy such as solar.

Optimal size of spherical rock salt balls as low-cost thermal storage materials for performance augmentation of hemispherical solar distillers: Experimental investigation and thermo-economic analysis

Passive solar distiller is one of the vital solutions to alleviate freshwater shortage problems. However, the production from solar distillers is limited due to their low efficiency. In this work, an experimental investigation is carried out to ameliorate the freshwater product of a hemispheric solar distillatory. Spherical rock salt balls are embedded in the basin saline water to improve the absorption rates for efficacious heat transfer of salty water and also act as a low-cost sensible energy storage material to promote the basin saltwater temperature in the inadequacy of solar irradiation periods. To determine the optimum size of the spherical salt balls that maximizes the best freshwater production of hemispherical distillers, four diversified sizes of salt balls (0.50, 1.0, 1.50, and 2.0 cm) are investigated and compared with the reference hemispheric solar distillatory (RHSD) under the same hot conditions of ElOued, Algeria. The findings indicated that the freshwater product of hemispheric solar distillers for using the spherical rock salt balls reached 6.77, 6.25, 5.92, and 5.67 kg/day.m2 for spherical rock salt balls sizes of 2.0, 1.50, 1.0, and 0.50 cm, respectively, compared to 4.65 kg/day.m2 yielded by the RHSD. The enhancement in the freshwater production for the usage of spherical rock salt balls reached 45.6%, 34.4%, 27.3%, and 21.9%, respectively. Moreover, under these conditions, the amelioration in the daily energy efficiency for utilizing the spherical rock balls is estimated to be 43.91%, 33.22%, 26.10, and 21.13%, respectively, compared to the RHSD. Additionally, the hemispheric distillers using the spherical salt balls show respectively a 28.83%, 23.47%, 19.73%, and 16.84% reduction in the freshwater production cost in comparison with that of RHSD. Conclusively, it is inferred that spherical salt balls with a size of 2.0 cm achieved the maximum thermo-economic performance of the hemispheric solar distillatory.

Experimental and numerical investigation of thermal performance of a new design solar parabolic dish desalination system

• A new design of Solar Parabolic Dish Desalination System (SPDDS) was proposed. • Τhermal performance of SPDDS was investigated experimentally and numerically. • Optical simulation for SPDDS was performed using COMSOL model. • The model showed that thermal performance of absorber within glass enclosure was promising. • The maximum daily thermal efficiency of SPDDS was calculated to be 36.04%. The objective of the present study is to construct a cheap, new design of small-scale solar parabolic dish desalination system made from reused local recyclable materials without complex parts and power source with advantageous approach due to its unique configuration. The desalting system including a new design of cleanable vessel acts as a boiler that accommodate inside a glass box to minimize the heat losses by the wind. The proposed system was investigated by experiments and numerical model. Moreover, the optical efficiency of the system was simulated using COMSOL model. The experimental data using different levels of salt concentrations and brine masses was compared to those of numerical to validate the model. The model validation revealed that the mean bias error and mean percentage error for brine were −1.05 °C and 0.86%, respectively, while the maximum predicted concentration ratio reached ∼16,000 and ∼9000 for ideal and real reflectors, respectively. The experimental results of were compared to those numerical to validate the model using different levels of salt concentrations and brine masses. The obtained daily average values of radiative heat transfer coefficient proved the effective role of the glass box and vessel in reducing the heat losses to surroundings. At brine mass of 0.75 kg and salt concentration of 15 g/kg, the increase of the salt concentration from 0 to 200 g/kg decreases numerically the daily productivity and daily efficiency from 500 to 320 ml/m 2 .day and from 88.60 to 19%, respectively. Experimentally, the maximum instantaneous and daily thermal efficiency were found to be 53.40% and 36.04%,respectively, while the cost of freshwater production from the proposed system was 0.64 $/l.