Experimental investigation of a multi-effect active solar still: The effect of the number of stages

In this work, the effect of the number of stages on the productivity of a multi-effect active solar still was experimentally investigated for the first time. Moreover, system performances in continuous and non-continuous modes were compared. For this purpose, indoor experiments were conducted on 4 similar solar still devices with different stages (1–4 stages) in order to accurately control the environmental conditions. In addition, water production was hourly measured during the whole 24-h experiment. The results show that with increased number of stages, distillate production can be predicted with a quadratic function. Moreover, adding a maximum of 6 and 10 additional stages can significantly increase production in continuous and non-continuous modes, respectively. It was also concluded that with more stages, the production enhancement is more in the continuous mode compared to the non-continuous mode, in a way that there is no significant difference between the performance of the single-stage device in continuous and non-continuous modes.