Experimental study on stepped solar still equipped with reflectors for the concentration of sugarcane juice

Abstract

The present study accentuate the noteworthiness of ongoing research in evolving sustainable sugarcane juice evaporation technologies to help the non-centrifugal sugar (NCS) industry. Concentrated sugarcane juice (CSJ) is the raw material for the production of variety of value added products. A stepped solar still (SSS) could be one of the inexpensive solutions to evaporate water from sugarcane juice. In this study, a SSS having internal and external reflectors (SSS-IR-ER) is tested at 25 mL/min of sugarcane juice for obtaining CSJ. The thermo-enviro-economic performance of SSS-IR-ER unit is compared with SSS and SSS-IR (SSS having internal reflectors) units. The final brix content (^oB) of the CSJ obtained from SSS-IR-ER is found to be maximum (20.7 ^oB) which is respectively, 16.90% and 7.25% higher than those of SSS and SSS-IR units. The total distillate output (condensate) and heat transfer coefficients show similar trends as that of brix values, which proves thermal dominance of SSS-IR-ER unit. For SSS-IR-ER, the convective and evaporative heat transfer coefficients were found to be maximum as 3.89 and 73.78 W/m²°C, respectively. The average values of energy and exergy efficiencies for SSS-IR-ER were, respectively, evaluated as 55.25% and 2.7% which were also observed maximum among the tested units. SSS-IR-ER also found to command in environmental and economic aspects with maximum values of total productive cost ($0.218), CO₂ mitigation (14.93 tonnes) and carbon credit earned ($186.73). It is inferred that SSS-IR-ER is more economical and thermally efficient than SSS and SSS-IR units.