High performance of a simple design, two effect solar distillation unit

Under a passive mode of operation, a transient analysis of a new, simple design, two effect solar distillation unit is presented. The unit consists mainly of a single sloped basin solar still of a shutter fashion type reflector, purging its vapor to a second effect still connected at the shaded side of the first effect still. Based on the energy balance for the different components of the two effects distillation unit, the hourly variation in the unit energies, temperatures, productivity, and efficiency was obtained. The effects of some design, operational, and environmental parameters on the distillation unit productivity are presented. On the basis of the numerical computations, it was observed that the unit first to the second effects volume ratio, the solar intensity, the base and side wall insulation, and the initial temperature of the basin water significantly influence the unit's productivity. The daily productivity increases to as high as 10.7 kg/m(2).d, for the proposed unit under the climatic conditions of the city of Dhahran, Saudi Arabia. The proposed distillation unit is simple, passive and adds no design, operation or maintenance complexities over the conventional single effect basin solar still.