Investigation on Solar Drying Characteristics of Ginger (Zingiber officinale) in a Reflector-Attached Solar Air Heater and Thermal Energy Storage System Using Nanomaterials

Abstract

By changing its design and materials, a solar dryer can help lower consumption and drying time. The dryer was run with a reflector-attached zigzag solar air heater thermally coated with 2% mass basis carbon nanotubes, 2% CuO, and 96% black paint with a reflector. To check the microstructure and morphology analysis of the nanopowders and coated surface, X-ray diffraction, scanning electron microscope, energy-dispersive X-ray, and elemental mapping have also been conducted. In this paper, the feasibility of the cabinet dryer with rotating trays was investigated to dry ginger slices in case of attaching an energy storage device. The moisture content of the ginger slices was successfully reduced from 90 to 12% within the time frame of 7 h 15 min. The different drying characteristics and quality parameters were evaluated and then compared in the case of the zigzag with coated surface and reflector, with coated surface and with reflector, respectively. The results show that using a reflector, it increases the air heater's outlet temperature by 10–12%, and using a coated surface increases the temperature by another 8–10%. The average thermal and exergy efficiency of an air heater was found to be 70.2 and 4.4%, respectively. The average overall thermal efficiency of carbon nanotubes + copper oxide-paraffin wax energy storage unit was 31.19%, with 11.9% as the average overall exergy efficiency. The energy storage increases the drying time by about 3 h during off-sunshine hours.