Comprehensive experimental and theoretical study of a novel still coupled to a solar dish concentrator

[Display omitted] •A novel solar still in a direct solar desalination system was studied.•A solar still in a PDC system was considered as key component.•A comprehensive mathematical model was developed for the system described.•Model showed the system is promising for small to medium scale desalination.•The system with a 3 m PDC can produce 75 kg distilled water per day. This work presents a solar parabolic dish collector system with a new design of a solar still mounted at its focal point for saltwater desalination. The system was investigated both experimentally and theoretically. A detailed and accurate mathematical model was developed for the system described. The proposed model includes two main parts: the modeling of saltwater heating in the evaporator before evaporation process starts, and the modeling of water vaporization in the evaporator and condensation of vapor produced in the condenser. Validation and verification of the model were done with experimental data, and the results of errors analysis showed that the model is reliable. A parametric study for some optical properties, structural and operational parameters was performed for the system. The results show that the collector optical efficiency, absorber reflectivity, dish aperture diameter, and absorber plate size have a significant effect on the distilled water produced and initial saltwater temperature, salinity and the amount of saltwater in the evaporator have no impressive effect. For a dish with an aperture of 2 m, when the absorber plate reflectivity reduces from 0.7 to 0.4 and parabolic dish optical efficiency increases from 0.5 to 0.8, the distilled water produced increases up to 120 and 80% respectively, while the influence of initial water salinity, temperature and its amount in the evaporator on distilled water produced is less than 10%. For a dish concentrator with an aperture diameter of 3 m and for specified conditions about 75 kg distilled water can be produced in a day for system time operating from 8:30 to 17:30.