Energy Conversion and Management: X (May 2022)
Transient mathematical modelling and investigation of radiation and design parameters on the performance of multi-effect solar still integrated with evacuated tube collector
Abstract
The advent of multi-effect solar still (MESS) provides an opportunity for improved yield, efficiency and gained output ratio (GOR) compared to the conventional still. It happens through the conservation of latent heat of evaporation from one stage to the next. In this present work, a lumped parameter model is developed to study the energy and exergy performance of the MESS. The transient solution for the varying solar energy supply is obtained using TRNSYS software. The TRNSYS and MATLAB linking available in TRNSYS software are effectively exploited to solve the heat transfer, mass transfer and exergy equations. An outdoor experiment was conducted using a MESS connected to an evacuated tube collector (ETC). The calculated results were compared with the experimental results, and a good agreement between them was observed. A maximum of 7.74% and a minimum of 1.62% error was observed between the experimental and numerical yield. Total yield, GOR and overall efficiency for a five-effect solar still were found to be 28.625 kg/m2day, 2.84 and 87.35%. The impact of the number of effects, basin size and basin water level on the yield, energy and exergy performance was also studied. The number of effects beyond seven shows no significant rise in water production. A lower amount of basin water and a higher evaporation area gives maximum yield and efficiency. However, a smaller basin area for the same quantity of water and energy supply has increased the water temperature to a higher value, eventually increasing exergy utilization. The yield, GOR and efficiency were maximum to be 8.6 kg, 3.36 and 109.01% for the basin area 0.56 m2 and 2 kg basin water quantity. The exergy efficiency was maximum to be 10.09% for the basin area of 0.16 m2 and 2 kg basin water quantity.
