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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: Solar collectors need to be inclined at the optimum angle to maximize the receiving energy. In spite of many theoretical and experimental investigations on optimization of solar collector inclination, there is an inconsistency in presented results. In this paper, solar global radiation on a horizontal surface was estimated using a mathematical model and the results were compared with the recorded data from the Zahedan city meteorological station. Total received solar energy by a flat inclined collector was determined in a certain day, and searching for the angle which has the maximum incident energy was the general procedure in determination of daily optimum tilt angle. In case of operational limitation for daily tilt adjustment, this procedure is repeated for other specific period of time and monthly, seasonal, semi-annual and annual optimum tilt angles were determined. A MATLAB-based code is used to calculate the daily optimum tilt angle. The results were in good agreement with the obtained data of a new constructed device. Finally, in the case of stationary devices, some recommendations were presented with respect to their typical application. [ABSTRACT FROM AUTHOR]