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In this study, a copper inclined stepped solar still was designed and fabricated to study the seawater desalination productivity of copper inclined stepped solar stills. The experimental setup mainly consists of two parts: a seawater settling and feeding tank and an inclined stepped solar still. The inclined stepped solar still with internal dimensions of L 1.8 m, W 1.2 m, and H 0.20 m consisted of 28 trays, and the tray dimensions are 0.6 m in height and 1.2 m in length. Its performance was tested in Bangi City - Malaysia, under Malaysian environmental conditions in the period from September 2016 to December 2016. The inclined stepped solar still was sealed to reduce vapour leakage to the environment. The experiment studies the effect of different environmental parameters (solar intensity, ambient temperature, wind velocity, humidity and cloud coverage) and operational parameters on the system productivity (water production and glass out, inner, vapour, water and tray “basin” temperature). The result shows that the productivity of the solar still was highly affected by environmental parameters. For example, the increase in solar radiation and ambient temperature increases the still temperature, and the difference between the cover inner and outer temperatures enhances the condensing process and water productivity. However, the decrease in humidity increases the productivity, the wind velocity significantly reduces the (T i − T o ) difference temperature, which adversely affects the productivity of the system, and the cloud coverage affects the solar radiation intensity. The productivity was 4383 mL/m 2 d; the best hourly efficiency was approximately 58% at 17:00, which can be explained by the highest solar radiation and ambient temperature with respect to time lag for the system. [ABSTRACT FROM AUTHOR]

Abstract: Transient mathematical models are presented for an active single basin solar still (ASS) with and without a sensible storage material under the basin liner of the still. Sand is used as a storage material due to its availability. The flowing water temperature is assumed to vary with time and space coordinates. Analytical expressions are obtained for various temperatures of the still elements as well as for the temperature of sand. The performance of the still with and without storage is investigated by computer simulation using the climatic conditions of Jeddah (lat. 21° 42′ N, long. 39° 11′ E), Saudi Arabia. Effects of mass flow rate and thickness of the flowing water for different masses of the storage material on the daylight P dl, overnight P on and daily productivity P d and efficiency η d of the still are studied. The dependence of P d and η d on the thickness and thermal conductivity of the basin liner material is also investigated. It is found that P d and η d decrease as the mass of the storage material increases, due to the increased heat capacity of the storage material. Furthermore, P d and η d are found to decrease with increasing thermal conductivity of the basin linear material. Therefore, it is advisable to fabricate basin liners of ASS from cheap insulating materials such as glass and mica with an optimum thickness of 3mm. On a summer day, a value of P d of 4.005 (kg/m2 day) with a daily efficiency of 37.8% has been obtained using 10kg of sand compared to 2.852 (kg/m2 day) with a daily efficiency of 27% when the still is used without storage. The annual average of daily productivity of the still with storage is found to be 23.8% higher than that when it is used without storage. [Copyright &y& Elsevier]