Performance study of an improved basin type vertical multiple effect diffusion solar still

ABSTRACT

Performance testing of floating wick basin type vertical multiple effect diffusion solar still with waste heat recovery (FW-BVMED-HR) was done, under outdoor conditions. The cumulative efficiency of the four effect FW-BVMED-HR increases by 33%, when the gap between partition plates is decreased from 16 mm to 10 mm. The cumulative efficiency decreases by 27% as the feed rate increases from 0.27 g/m²/s to 0.38 g/m²/s. Increase of basin water depth had little effect on the cumulative efficiency of the still. The cumulative efficiency increased by 58% when the number of effects was increased from 2 to 7.

KEYWORDS:

• Solar distillation
• vertical multiple effect
• floating wick
• cumulative efficiency
• heat recovery

Nomenclature

Ag	=	Area of glass cover, m2
d	=	Depth of basin water, cm
f	=	Feed water flow rate per unit area of the partition plate, g/m2/s
Gg	=	Global solar radiation on glass cover, W/m2
GHT	=	Hourly global solar radiation on glass cover per unit area, J/m2/h
GT	=	Total daily solar radiation on glass cover for experimental period, MJ/m2/day
Hfg	=	Latent heat of water, J/kg
md	=	Mass of distillate, kg/h
${\dot{m}}_e\ast$	=	Steady-state evaporation flux from wick under constant solar radiation, kg/m2/s
${\dot{m}}_f$	=	Feed rate per unit area, kg/m2/s
n	=	Number of effects
P	=	Distillate productivity, kg/m2/day
Ta	=	Average daily ambient temperature, °C
Tf	=	Feed water temperature, °C
Vw	=	Wind velocity, m/s

Greek letters

δp	=	Gap between partition plates, mm
ηc	=	Cumulative efficiency

Subscripts

m

=

Mean

Abbreviations

FW-BVMED-HR	=	Floating wick basin type vertical multiple effect diffusion solar still with heat recovery
PVC	=	Polyvinyl chloride
VMED	=	Vertical multiple effect diffusion
TDS	=	Total dissolved solids

Acknowledgments

The authors gratefully acknowledge that this work has been funded by Water technology initiative, Department of Science and Technology, Government of India vide letter no. DST/TM/WTI/2K13/122(G) dated 20/05/2014.

Additional information

Funding

This work was supported by the Water technology initiative, Department of Science and technology, Government of India [DST/TM/WTI/2K13/122(G) dated 20/05/2014].