Analyzing the effect of an enlarged flat plate reflector (FPR) on a vertical multiple-effect diffusion solar still's (VMEDS) performance

The vertical multiple-effect diffusion solar still (VMEDS) has a great design advantage in that the narrow gaps between partitions allow it to stand tall and be space-efficient. Unfortunately, VMEDS require additional equipment for absorbing sufficient solar energy. One with the simplest configurations is the flat plate reflector (FPR) which is essentially a fixed angle mirror. However, previous studies have pointed out that the direction of VMEDS with FPR needs to be adjusted relative to the sun's position once a day. To eliminate this troublesome rotation of VMEDS, as well as to compensate for the decrease of daily distillate productivity ∑md,total caused by fixing VMEDS, a VMEDS with an enlarged FPR is introduced. Also, a new graphical model -- to calculate reflected radiation from FPR and absorbed on VMEDS for the case that width of FPR is not equal to that of VMEDS -- is introduced. The results show that the ∑md,total of the fixed VMEDS with an enlarged FPR area is less than that of a rotated VMEDS whose FPR area is equal to VMEDS. However, ∑md,total can be increased by enlarging FPR for fixed VMEDS, making it a better choice to eliminate the troublesome rotation of VMEDS with FPR.