Experimental evaluation on the capillarity effect of different wicking structure incorporated in a patterned absorber facilitating solar interfacial evaporation

Solar interfacial evaporation is an effective desalination method, and its success depends on the evaporation rate and wick structure. With this in perspective, this paper presents and demonstrates the capability of a patterned solar absorber on interfacial evaporation, thereby, on seawater desalination. This work consists of two parts; wicking and evaporation. Preliminary lab-scale studies were carried out on polyvinyl alcohol towel, cotton cloth, and air-laid paper to identify a suitable wick material. Static and dynamic absorption rate and vertical wicking water phenomena were used as the benchmark for comparison and selection. The tests showed that polyvinyl alcohol outperformed air-laid paper and cotton by a factor of 2.0 and 1.5 in vertical wicking rate and 150% and 200% in static absorption rate. Also, the dynamic absorption rate of polyvinyl alcohol was 14.0 and 7.0 times higher than air-laid paper and cotton. In the evaporation study conducted on a prototype, the effect of bulk heating and interfacial heating on evaporation rate was determined. The evaporative efficiency for bulk heating and interfacial heating using polyvinyl alcohol absorber is 38% and 68%. Further, the study was extended to determine the influence of the black coating on the polyvinyl alcohol structure. The findings suggest that under one sun irradiation coating improves the conversion efficiency (solar-to-vapor) up to 89%, with 1.49 kg m −2 h −1 evaporation rate. These outcomes highlight polyvinyl alcohol with black coating as a suitable candidate for interfacial evaporation. This work helped determine an optimized evaporative design that could improve the evaporation rate in interfacial heating-assisted desalination.