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This study focused on the optimal production feasibility of distilled water from the concentrate of a reverse osmosis device using an evacuated tube collector basin solar still. The characteristic effect of the device's condenser on the produced freshwater volume was evaluated to improve the performance of the solar still, resulting in productivity enhancement. The direct contact of two faces of the cubic condenser with water vapor results in the doubling of the effective surface area. However, freshwater production was decreased by eight times compared to the case where only one face of the condenser is in contact with water vapor. This reduction was attributed to the shorter path taken by the condensed droplets. At the bottom of the evacuated tube collector, some building mineral pumice was used to prevent the formation of large water vapor bubbles. According to this methodology, the average daily production of distilled water from the concentrate of the reverse osmosis unit with a total dissolved solids of 15200 ppm was achieved at 4.58 ± 0.12 L. m − 2 . The quality of produced distilled water revealed that solar desalination using an evacuated tube collector basin solar still can be a notable and economical solution for the concentrate treatment of reverse osmosis. [Display omitted] • The longer the droplets' path on the glass condenser's surface, the higher the freshwater production rate. • The movement path of liquid droplets to the outlet with angles of θ = 0 ° is equal to the length of the condenser. • The ETC has the potential to transfer part of the salty water by the rise of large water vapor bubbles. • Building mineral pumice can be used to prevent the formation of large vapor bubbles at the bottom of the ETC. • Modified ETC basin solar still can be a considerable solution for the desalination of RO concentrate. [ABSTRACT FROM AUTHOR]

The solar still, in which saline or brackish water is converted into freshwater using renewable solar energy, can be an effective solution to water scarcity. Inclined solar stills are well-known due to their high production yields compared to other types of solar stills. In this study, an inclined weir-type solar still was developed as a modified inclined solar still with an emphasis on the effect of structural parameters, such as weir height, distance between weirs, and distance between the absorber plate and the condenser cover, on distilled water production. The optimal values of structural parameters for the maximum freshwater production were specified by the response surface methodology and a quadratic model derived from a Box-Behnken design model. The results showed that the operational variables of the inclined weir-type solar still system significantly impacted the water production volume. Using a weir height of 2 cm, a distance of 3.5 cm between weirs, and a distance of 15 cm between the absorber plate and the condenser cover, the maximum water production volume was achieved at 6.474 kg m−2.day−1. The selected model had R 2 , R adj 2 and R pred 2 values of 0.9978, 0.9939, and 0.9756, respectively. The maximum and minimum volumes of the produced water were obtained as 6.64125 and 1.79792 kg m−2. day1, based on the multiple response prediction of the variables. According to the validation tests, the model's accuracy in prediction of the maximum amount of freshwater production was notable (97.49%). [Display omitted] • The IWTSS, as a modified inclined solar still was fabricated. • The effect of operational parameters on IWTSS productivity were evaluated. • The structural parameters of IWTSS affecting water production volume were optimized based on the BBD model. • The simultaneous decrease in h w and d w led to increasing device productivity. • In the modified inclined solar still, the water surface area was increased at optimal conditions. [ABSTRACT FROM AUTHOR]

Solar water desalination is still one of the most efficient techniques in water and wastewater treatment. In the present study, an evacuated tube collector (ETC) was used as the basin of the solar still. A cube-shaped glass condenser was attached on top of the ETC for vapor condensation. The main purpose was to investigate the effect of condenser geometry, including volume, surface, and wall thickness on distilled water production. The optimal conditions to produce a maximum volume of distilled water were determined using response surface methodology (RSM), based on the Box-Behnken design (BBD) model. All selected operating factors significantly affect the volume of water produced by solar desalination. The maximum volume of produced water was 7.231 kg.m−2.day−1, which was obtained at the condenser volume of 2940 cm3, the condenser wall thickness of 4 mm, and the condenser surface of 3360 cm2. R 2 and R adj 2 values in the selected model were 0.9934 and 0.9815, respectively. The validation experiment confirmed the high accuracy of the BBD model for predicting the optimal conditions to achieve the maximum amount of produced water. [Display omitted] • The modified ETC, on which embedded a cube-shaped glass condenser, was fabricated. • The effect of volume and surface of the condenser on V.W separately was evaluated. • The operational parameters affecting V.W were optimized based on the BBD model. • The influence of the condenser surface was more evident than other operating factors. • In modified ETC, the specific surface area of the condenser was increased. [ABSTRACT FROM AUTHOR]

Abstract: Most part of Iran is dominated by arid and semi-arid areas due to low annual rainfall. The need for production of fresh water from brackish water is considerably high, especially in dry regions. In this study 1month daily-based experimental data from a solar still site has been reported. The technical and operational problems of this site which finally contributed to the total cease of the site are described. Then a detailed analysis is investigated on progress of a prototype which constructed in order to solve the site’s problems. The results of 1month of experimental data of the final design showed that the last prototype could be used to solve the current problems of the site. The average fresh water production for the modified cascade solar still is around 6.7lit/daym2, which shows 26% increase in compare to the initial site’s units. The conductivity of the produced distilled water reduced to 10–20μS/cm which is an acceptable range in the solar still science. Moreover, a mathematical model is proposed to simulate the modified still. The model results and experimental data show a significant increase in the fresh water production in compare with the initial site’s stills. [Copyright &y& Elsevier]