Freshwater Yield Research Articles

Performance evaluation and multi-objective optimization of hydrogen-based integrated energy systems driven by renewable energy sources

This study proposes an integrated energy system using hydrogen storage to realize the efficient utilization of renewable energy sources and reduce the fluctuation when renewable energy is connected to grid. The system utilizes solar and wind energy to realize hydrogen production, desalination, and CCHP. First, the energy, exergy, and economic evaluations for the proposed system are carried out, and then an in-depth analysis of the key operating parameters is performed. The system achieves energy efficiency, exergy efficiency, and cost rate of 48.49 %, 19.98 %, and 7.969 $/h, respectively. And the exergy analysis shows that the main exergy destructions are caused by the parabolic trough solar collector and the transcritical CO2 power cycle. The parametric analysis demonstrates when solar radiation flux and wind speed increase, the exergy efficiency and hydrogen production are increased, but the cost rate is increased accordingly. Finally, two sets of multi-objective optimization schemes are performed combining the artificial neural network with the Non-dominant genetic algorithm-II. For the optimized fresh water output, cost rate, and exergy efficiency, it is achieving improvements of 51.73 %, 8.4 %, and 3.6 %, and for the optimized hydrogen production, cost rate, and exergy efficiency, it is increased by 12.53 %, 0.564 %, and 0.75 %, respectively.

Geometric optimization to improve the performance of a new design of concentration‐based solar distiller using particle swarm optimization algorithm

AbstractSolar distillers are one of the oldest and simplest technologies for desalinating salt water using solar energy. The main problem is the low freshwater production compared to the amount of energy input from the sun. To overcome this problem, a solar distiller was developed using a parabolic trough concentrator to increase the freshwater yield. The geometry optimization of various parameters of the developed system was also studied using the particle swarm optimization (PSO) algorithm to obtain the optimal design and give the improved freshwater yield. The simulation is carried out based on the algorithm using the climatic condition data of Rabat City, Morocco. Numerical resolution of the energy balance equations was performed using MATLAB code. In terms of flexibility, speed, and global convergence, this method's final results were satisfactory. The maximum optimized freshwater yield using the PSO approach is 12.83 kg/m2 and the maximum optimized energy and exergy efficiency were about 204.7% and 34.3%, respectively. Furthermore, the results showed that the absorber basin accounts for the highest exergy destruction, 88.7% of the total optimized exergy destruction was found from exergy analysis.

MOF-based photothermal Janus membrane with robust anti-fouling performance for enhanced membrane distillation

As a promising desalination technology, photothermal membrane distillation (PMD) is confronted with challenges such as low freshwater yield and membrane fouling. Herein, we have introduced a copper-based metal-organic framework (Cu-CAT) into a hydrophilic/superhydrophobic polyvinylidene fluoride (PVDF) Janus tree-like nanofiber membrane (TLNMs) to construct photothermal Janus TLNMs (P-Janus TLNMs) for enhanced PMD. Given the exceptional photothermal properties of the hydrophilic Cu-CAT layer, coupled with the fine pore structure and elevated porosity characteristics of the superhydrophobic PVDF TLNMs, P-Janus TLNMs have demonstrated outstanding performance when integrated into a PMD system. Upon exposure to solar illumination of 1 kW·m−2, the P-Janus TLNMs achieved a remarkable surface temperature of 88 °C, yielding a permeation flux of 1.46 L m−2 h−1, a salt rejection rate exceeding 99.99 %, and an energy utilization rate of 81 %. Furthermore, after 20 days of continuous operation with simulated seawater containing oil and surfactant, the P-Janus TLNMs presented a salt rejection of 99.9 % and a stable permeation flux of 1.71 L m−2 h−1 at the feed/permeate temperatures of 24/20 °C. This work introduces a novel membrane with immense potential for boosting permeation flux and enhancing anti-fouling properties in PMD, thereby advancing the frontier of sustainable seawater desalination.

A geothermal-based freshwater/cooling system assisted by heat recovery sections: 3E analysis and techno-economic optimization using genetic algorithm

The proposed system uses a dual-loop organic Rankine cycle, a reverse osmosis desalination unit, an absorption cooling unit, and a thermoelectric generator to produce electricity and freshwater for urban areas. A thorough assessment of the system's thermodynamic and economic performance has been conducted, with a parameter-based investigation to assess the effect of key variables on the system performance. The parametric study indicates that rising the geothermal mass flow rate enhances the energy efficiency, but lowers the energy efficiency and affects the cooling requirements. Moreover, the optimum inlet temperature in turbine 1 increases the desalination efficiency up to 105.02 kg/s at 115 °C, and higher temperatures reduce the performance and system efficiency. Adjusting the temperature difference at the pinch point at Evaporator1 is crucial for system efficiency, with trade-offs between freshwater output, expenses, and exergy efficiency. The capability of the system to produce up to 6,048,000 L of potable water daily signifies a monumental leap towards meeting the water demands of nearly 42,000 individuals, based on European consumption standards. Lastly, the application of genetic algorithms in the optimization process results in an exergetic efficiency of 32.79 % and a cost rate of 58.05 $/h, demonstrating the system's enhanced operational effectiveness.

Enhancing conical solar still performance using high conductive hollow cylindrical copper fins embedded by PCM

The present study aims to enhance the efficiency of the conical solar distiller in producing water during both day and night. This will be achieved through design enhancements, such as increasing the surface area of the distiller to maximize solar energy absorption and improve condensation rates. High thermal-conductivity cylindrical fins have been used, and their role will be investigated. These fins may be hollow and extended, with or without the inclusion of phase change material (PCM). Consequently, copper tubes are positioned at the base of the distiller basin, both with and without the inclusion of phase-changing paraffin wax material inside the hollow tubes. A comparison is made between the performance of three configurations: the first configuration is traditional, the second configuration includes fins without the incorporation of PCM, and the third configuration includes PCM-based fins. This comparison is crucial as it provides a clear understanding of the impact of each design enhancement on the distiller’s performance. The study findings indicated that the arrangement with hollow fins filled with PCM had the highest level of freshwater output. Furthermore, the results showed that the combined output of conical solar distillers equipped with fins made of copper tubes, both with and without PCM, were 7.50 and 6.75 L/m2/day, respectively. The cumulative production of conventional conical distillers is 4.85 L/m2/day. Freshwater output improved by 54.64 and 39.17 % when using hollow copper tubes with and without PCM within 24 h, compared with the conventional configuration. During night-time hours, it was observed that the freshwater output of distilled water from salt water significantly improved by 550 % when utilizing copper tubes loaded with PCM, compared to distillation using empty copper tubes. The maximum daily efficiency of conical distillers with fins with and without PCM were 73.6 % and 80.3 %, respectively. These results showed that conical distillers using copper tubes hollow filled with PCM represent good options for obtaining higher performance than distillation.

Solar still basin measurements and liner material variance for improved water desalination efficiency

Access to potable water remains a global challenge, and solar stills offer a sustainable desalination solution. Solar stills however have low desalination efficiencies. The impact of basin measurements and liner material variance on their performance have not been evaluated, and this study sought to investigate this through modelling with the objective of improving the performance of a one-slope solar still. MATLAB is employed in the model development and simulations. The developed model is validated using other experiments in literature. The analysis is done with Machakos (1.52°N, 37.2°E), Kenya climatic conditions as a reference. Various basin liner materials including aluminium, synthetic graphite, brass, galvanized iron and stainless steel are examined based on their thermal properties. Different width-to-length ratios ranging from 0.14 to 0.86 are investigated. Basin liner thicknesses of between 2 mm and 6 mm are evaluated. A parametric study is conducted to determine the correlation between liner material thickness and basin dimensions, and their combined impact on freshwater yields. From the results, synthetic graphite had the best performance, followed by aluminium, brass, galvanized iron and stainless steel with efficiencies of 35.04 %, 24.02 %, 17.02 %, 14.13 % and 12.39 %, respectively. Thus, synthetic graphite outperformed aluminium, brass, galvanized iron and stainless steel by 31.4 %, 51.43 %, 59.675 % and 64.64 %, respectively. A width-to-length ratio of 0.45 yields optimal results, while a liner material thickness of 4 mm is found to be ideal across all materials. The parametric study further reveals that width-to-length ratio has a higher significance on freshwater yields compared to liner material thickness.

Investigating the impact of nanofluids and exergy metrics for integrated solar-biomass SCO2 power and desalination cycles

Several strategies have emerged for utilizing waste heat across diverse sectors. Yet, integrated systems that merge power generation with freshwater production, especially those leveraging renewable energy, remain relatively unexplored. Addressing this gap, a novel solar biomass-driven system is under development for power generation and desalination facilities. In the suggested system, rather than wasting the energy of a supercritical CO2 power cycle, a bottoming cycle is proposed to augment energy utilization factor (EUF). By integrating humidification-dehumidification, thermal vapor compression, and reverse osmosis (HDH-TVC-RO) with a multi-effect distillation (MED) unit, freshwater production rate is significantly enhanced. The outcomes reveal a freshwater output of 29.36 kg/s, a gained output ratio (GOR) of 17.36, and the EUF of 3.372. Various nanofluids have been assessed for the solar collector and due to superior total exergy efficiency and less corrosion effects, Cu- and carbon-based nanoparticles are recommended. Sensitivity analysis indicates that increasing the pressure ratio of compressors boosts the total GOR. Furthermore, adjustments to both the parameters of pressure of steam fed to HDH-TVC, and the compressor pressure ratio demonstrate a linear effect on EUF behaviour.

Numerical and experimental investigation of floating wick solar still with a porous-media system

Wick-based solar desalination and solar-driven interfacial evaporation have attracted significant attention for their high efficiency in evaporation and salt removal. This study presents both experimental and numerical models for wick solar desalination. Cotton fabric, coated with black carbon for enhanced radiation absorption, was used as the evaporation medium in experiments due to its superior desalination, capillary, and salt rejection properties. Experimental results showed an evaporation rate of 1.57 kg/m2·h and efficiency of 81 % with freshwater. For saltwater (3.6 % salinity), the evaporation rate and efficiency were 1.24 kg/m2·h and 71 %, under 1000 W/m2 radiation. After validating the numerical model, the effects of porosity, capillary pressure, wick thickness, and thickness of the fabric’s upper (solar absorber) layer were examined. Results showed that reducing the solar absorber fabric thickness (from 9 mm to 0.6 mm), lowering porosity (from 0.97 to 0.3), and increasing wick thickness (from 1.5 mm to 10.5 mm) improved evaporation rates by 58.6 %, 27 %, and 28.4 %, respectively. Capillary pressure and fabric submerged length had minimal effects on evaporation. The model estimates that in real conditions at Jask coastal port (Iran), a configuration with greater wick thickness (6 mm vs. 3 mm), reduced solar absorber fabric thickness (1 mm vs. 1.5 mm), and lower porosity (0.75 vs. 0.93) could increase annual freshwater output by 26.6 % (from 796.6 to 1008.4 kg/m2). The cost per liter of produced water in the best-case scenario is estimated to be $0.0045.

Effect of a black paint coated double layer cellulose sponge as an absorber in a solar interfacial distillation: an experimental investigation

ABSTRACT In the recent past, direct solar energy-based distillation for the production of freshwater has been the subject of extensive research. Nevertheless, the outdoor experimental study did not thoroughly investigate the incorporation of the interfacial absorber concept in conventional solar distillation. Therefore, the impact of a simple black paint spray coated double-layer cellulose sponge on the freshwater yield of a solar distillation system is examined in this work. The modified top layer of the cellulose sponge exhibited an increase in the average absorbance of solar radiation from 27.59% to 86.88% in the wavelength range of 200–2400 nm. The maximum freshwater yield of the black paint-coated cellulose sponge-based floatable interfacial absorber (Unit II) was found to be 3.85 L/m2/day, which was 29.27% higher than that of the conventional solar distillation unit (Unit I) upon 4 days of experimental investigation. Comparably, Unit-II outperformed Unit I with an overall evaporation efficiency of 46.08%, which was 10.22% higher than Unit I. Furthermore, Unit II attained an exergy efficiency of 64.24%, surpassing Unit I by 28.5%. Therefore, in order to address the water shortage in rural areas of society, this work would assist researchers in designing and developing an effective interfacial absorber.

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.

Biomimetic hydrogel evaporator with excellent salt-rejection performance via edge-preferential crystallization and ion-transport effects

Solar steam generation has been considered a compellent desalination technology due to its environmental friendliness and sustainability, while interfacial salt crystallization and low freshwater yield are two serious issues that constrain its widespread application. In this work, inspired by lotus seedpod, a biomimetic evaporator containing conductive hydrogel was fabricated through 3D printing. The printed evaporator has excellent solar absorption, good mechanical properties, high water capture ability, and reduced vaporization enthalpy, which are exactly desired by good evaporators. Furthermore, the vertical micro-channels and networks inside hydrogel promote the transport of ions from the interface to bulk seawater, and the constructed edge petals drive salt ions to crystallize at the edges, both of these strategies suppress the salt crystallization and ensure long-term continuous operation of the evaporator in concentrated (25 wt%) seawater. Due to these positive effects, the evaporator can achieve 2.413 and 1.889 kg·m−2·h−1 steam yield under one sun in pure water and concentrated (25 wt%) seawater, which is much higher than the 2D evaporator and competitive among the reported evaporators. This work paves the road for the practical utilization of hydrogel in solar desalination.

Performance analysis of an SPD integrated with a stepped pyramid solar still: experimental study

AbstractWater scarcity poses a major challenge for the next generation. Additionally, increasing agricultural and industrial activities are creating an unprecedented demand for freshwater supplies throughout Egypt. The Nile River serves as Egypt’s primary water source, accounting for 69.4% of the total water resources. Moreover, Egypt's annual share of water has decreased to approximately 500 m3 per person because of the completion of the Renaissance dam in Ethiopia and the rapid increase in population growth. Solar distillation has been presented as a long-term and promising method for producing edible drinkable water. The present research goal is to increase the daily freshwater output from a stepped pyramid solar still (SPSS) by coupling with a solar parabolic dish (SPD). The proposed system consists of a conventional pyramid solar still (CPSS) and a modified pyramid solar still (MPSS). The main components of an MPSS include an SPSS, a PV panel, an SPD with a spiral coil, a circulating pump, and an Arduino Mega Unit. The developed system was designed, fabricated, and verified from July to August 2023 at the Faculty Engineering, South Valley University. The results of the experiments indicated that the daily productivity of freshwater from MPSS was greater than that from CPSS and reached 6038 and 2612 mL/day, respectively, with an increase in the daily yield of 131%. The peak energy efficiency is 56% for the MPSS and 24% for the CPSS. The peak exergy efficiency is 4.26% for the MPSS and 3.79% for the CPSS. Additionally, the cost analysis of the suggested system revealed that the estimated cost per liter of the proposed system is 0.01635 USD/L.

Comparative performance investigation of conventional and modified stepped basin pyramid solar still with improved insulation: Experimental evaluation

This study focuses on modifying the insulation of a stepped basin pyramid solar still (SBPSS). The modified SBPSS with both side insulation and the conventional SBPSS with one side insulation of the base were compared in terms of basin and basin water temperature, freshwater output, energy and exergy efficiency, payback period, and production cost. The research was carried out on two identical SBPSSs, where 0.25 m2 was the evaporation area for each case. In modified SBPSS, the insulation on both sides of the base significantly reduced heat loss, which was justified by the higher basin and basin water temperatures than conventional SBPSS. The maximum basin temperatures for conventional and modified SBPSSs were 50.49 °C and 53.74 °C, respectively, with maximum basin water temperatures of 47.21 °C and 52.86 °C. The modified SBPSS provided more freshwater (1.24 L/m2) than conventional SBPSS (0.93 L/m2) as a result of the rapid evaporation rate caused by the higher basin water temperature. For conventional and modified SBPSSs, the average energy efficiency was 22.33 % and 27.51 %, respectively, and the average exergy efficiency was 4.71 % and 6.90 %, respectively. The modified SBPSS provided freshwater at a 24.27 % lower price than the conventional SBPSS.

The Thermodynamic‐Analysis‐Derived Structure Optimization on the Solar Thermal Localized Desalination and Water‐Treatments

AbstractThe solar thermal localization (STL) technology is promising and cost‐effective for desalination or wastewater treatments, but currently in an insufficient status on its structure optimization. This study emphasized the water‐cooled STL (WSTL) system and its step‐forward modifications, involving the air‐insulated WSTL (AWSTL) system and the vacuum WSTL (VWSTL) system, together with their thermodynamic modeling analysis on energy‐water conversions, heat‐mass transfers, and energy losses. Results indicated the best‐performing VWSTL mode can achieve a freshwater yield as high as 1.503 kg·m−2·h−1 at energy efficiency of 68.0% (the light intensity at 1500 W·m−2 indoor), and that of 4.31 kg·m−2·day−1 at energy efficiency of 47.5% (the 8‐h averaged solar light intensity at 769.7 W·m−2 outdoor per‐day) whose energy efficiency is exceeded all competitors in open literature. There likely is an improvement space in applying better evaporation materials.

4E assessment of pyramid distiller performance utilizing V-corrugated wick material and TiO2 nanoparticles with hybrid solar heating

This study aims to increase freshwater productivity and thermal performance while improving the economic determinant of the traditional square pyramid distiller. The study was conducted on four modified pyramid distillation systems and their impact on 4E (Energy, Exergy, Economic, and Environmental). The V-corrugated wick material was combined with the water basin in the first configuration (AHPSS-1). The second system uses the same components but integrates a Solar Air Heater (SAH) to raise the water temperature (AHPSS-2). In the third proposed system, a hybrid solar heating system was used by combining a PV-powered electric heater with the previous system (AHPSS-3). The fourth configuration was similar to the third but with the addition of titanium oxide nanoparticles in the water to augment heat transfer performance (AHPSS-4). Thermal analysis of the proposed systems was performed to evaluate their thermal performance in various aspects of energy and exergy efficiency relative to the Conventional Pyramid Distiller (CPSS). In addition, an economic and environmental analysis was conducted for each case of the proposed systems. The outcomes showed an apparent enhancement in thermal and economic analyses versus the CPSS for the four proposed systems. Moreover, there was an improvement in productivity by 27.6, 102.5, 147.8 and 161.5 % for AHPSS-1, AHPSS-2, AHPSS-3, and AHPSS-4 severally. Consequently, the performance of the fourth proposed system was optimum compared to other cases, where the total freshwater yield of the conventional and novel pyramid solar distiller reached 3.9 and 10.2 L/m2. In addition, the daily thermal efficiency and the cost of one liter reached 69.8% and 0.011 USD. Furthermore, the annual CO2 emissions for the modified configuration were estimated at 9.44 and 19.75 tons/year versus 7.48 tons/year for CPSS. Also, the enviroeconomic parameters ranged from 136.81 to 286.35 USD/year.

Design of MOF-Based Solar Evaporators with Hierarchical Microporous/Nanobridged/Nanogranular Structures for Rapid Interfacial Solar Evaporation and Fresh Water Collection.

Interfacial solar evaporation (ISE) holds considerable promise to solve fresh water shortage, but it is challenging to achieve high evaporation rate (Reva) and fresh water yield in close system. Here, we report design and preparation of MOF-based solar evaporators with hierarchical microporous/nanobridged/nanogranular structures for rapid ISE and fresh water collection in close system. The evaporators are fabricated by growing silicone nanofilaments with variable length as nanobridges on a microporous silicone sponge followed by grafting with polydopamine nanoparticles and Cu-MOF nanocrystals. Integration of the unique structure and excellent photothermal composites endows the evaporators with high Reva of 3.5-20 wt% brines (3.60-2.90 kg m-2 h-1 in open system and 2.38-1.44 kg m-2 h-1 in close system) under simulated 1 sun, high Reva under natural sunlight, excellent salt resistance and high fresh water yield, which surpass most state-of-the-art evaporators. Moreover, when combined with a superhydrophilic cover, the evaporators show much higher average Reva of real seawater, remarkable fresh water yield and excellent long-term stability over one month continuous ISE under natural sunlight. The findings here will promote the development of advanced evaporators via microstructure engineering and their real-world ISE applications.

Sensitivity analysis on heat pump - mechanical vapor recompression desalination system by recovering waste heat of offshore power converter station

Abstract Offshore wind power converter stations produce massive low-temperature waste heat, which can hardly be used constrained by their offshore location. Therefore, the recovery of the waste heat has been raising widespread concern. Meanwhile, a large amount of fresh water is needed for its cooling system. So, a novel system combining high temperature heat pump and a mechanical vapor recompression system (HP-MVR) was proposed, and sensitivity analysis was performed to optimize it. The heat pump was used to absorb the waste heat and to produce high temperature water. The mechanical vapor recompression system was adopted to produce fresh water and to recover the condensation heat from the steam. In order to determine the impact parameters on the two crucial performance indicators of freshwater production and unit energy consumption, this article introduces a sensitivity analysis method, focusing on analyzing the sensitivity of the three operating parameters of heat pump condensation temperature, saturated water vapor inlet temperature entering the compressor, and freshwater condensation temperature to these two performance indicators. The results show that the sensitivity coefficients of heat pump condensation temperature, saturated water vapor inlet temperature entering the compressor, and freshwater condensation temperature are 1.13, -0.26, and 1.56. So, the freshwater condensation temperature has the most significant effect on freshwater output. Their sensitivity coefficients to unit energy consumption are 1.02, 1.41, and -0.64. The saturated water vapor inlet temperature entering the compressor has the most significant impact on the required power consumption per unit of freshwater. It will give some guidance for the application of low-temperature waste heat in seawater desalination and the reduction of operating costs.

Physical and chemical characterization of remote coastal aquifers and submarine groundwater discharge from a glacierized watershed

AbstractCoastal aquifers play an important role in marine ecosystems by providing high fluxes of nutrients and solutes via submarine groundwater discharge pathways. The physical and chemical characterization of these dynamic systems is foundational to understanding the extent and magnitude of hydrogeologic processes and their subsequent contributions to the marine environment. We describe a km‐scale experimental field site located in a glaciofluvial delta entering Kachemak Bay, Alaska. Our characterization applies geophysical (ERT and HVSR), hydrogeologic (grain size analyses, slug tests and tidal response analyses) and geochemical (major ions and stable water isotopes) methods to describe the complexity of coastal aquifers in proglacial environments currently experiencing rapid transformations. The hydrogeologic and geophysical techniques revealed thick (20–84 m) sediments dominated by sands and gravels and delineated zones of freshwater, brackish water and saltwater at both high and low tides within the subterranean estuary. Estimates of hydraulic conductivities via multiple approaches ranged from 2 to 250 m d−1, with means across the four methods within the same order of magnitude. Tidal response analyses highlighted a coastal aquifer in strong connection with the sea as evidenced by clear spring‐ and neap‐tidal signals within a proximal piezometric hydrograph. Geochemical sampling revealed coastal groundwaters as substantially enriched in solutes compared to proximal river samples with limited variability across seasons. A clear connection between the Wosnesenski River and the adjacent aquifer was also observed, with concentrated recharge from the river corridor during the meltwater season. This combination of approaches provides the basis for a conceptual model for coastal aquifer systems within the Gulf of Alaska and an upscaled mean daily yield of freshwater and solutes from the delta subsurface. Our findings are critical for subsequent numerical simulations of groundwater flow, tidal pumping and chemical reactions and transport in these understudied environments. This approach may be applied for low‐cost, large‐scale hydrogeologic investigations in coastal areas and may be particularly useful for remote sites where access and mobility are challenging.

Experimental Investigation of Single Slope Solar Still by Varying Water Depth and with External Reflector

Solar distillation converts salt water into drinkable water, requiring minimal maintenance and energy-saving. However, the desalination process has drawbacks because the system's slow evaporation and condensation rate leads to low freshwater output. Consequently, this method is not widely utilized due to its limited productivity. To address this issue, the study's primary aim was to enhance the productivity of the single-slope solar still. This was achieved by altering the water depth from 3 cm to 6 cm and incorporating an external reflector. The experiments were conducted in Coimbatore, Tamil Nadu, India (11.0168° N, 76.9558° E), with a condensing cover inclined at 11 degrees. The research occurred on varying days between October and November 2023, with water depths ranging from 3 to 6 cm. A comprehensive analysis investigated the influence of different factors on daily production, such as ambient temperature, solar intensity, and inner and outer glass temperatures. The experimental results indicate that the solar still with a single basin, operating at a water depth of 3 cm, achieved the highest water productivity (2.68 L/day) and displayed the best efficiency (30.52%) compared to 4, 5, and 6cm depths. Furthermore, incorporating an external reflector into the solar system still demonstrated a notable elevation in temperature, resulting in a significant boost in water productivity of 3.085 liters per day. This improvement also led to an increase in efficiency of 35.1%.

Comprehensive thermodynamic and economic analysis of an LNG cold energy recovery system using organic Rankine cycle and freezing-centrifugal desalination for power and water cogeneration

In this study, the LNG cold energy recovery combined with a freezing-centrifugal desalination system is proposed. The thermodynamic and economic analysis is also carried out of the proposed system. To verify the results of sea ice centrifugation process, experimental analysis of sea ice centrifugal desalination is presented based on different types of sea ice: slurry and solid, which are prepared by the method of suspension crystallization method and progressive freezing method, respectively. The experimental outcomes demonstrated that higher rotation speeds and longer centrifugal times enhanced the desalination rate but resulted in decreased freshwater yield in both slurry and solid ice. For the slurry sea ice, achieving a rotation speed of 5000 rpm and a centrifugal time exceeding 3.0 min resulted in melted water with a salinity level below 0.05%, satisfying the standards of drinking water. Moreover, the unit product cost, payback period, and unit cost of CO2 emission reduction for the proposed system are 0.49 $/t, 3.25 years and 18.92 kg/$, respectively. While the unit product cost, payback period, and unit cost of CO2 emission reduction for the conventional system are about 0.84 $/t, 4.80 years, and 15.66 kg/$, respectively. Hence, the proposed system shows higher economic and environmental performance.