Performance evaluation of modified forced convection solar dryer with energy storage unit for drying of elephant apple ( Dillenia indica )

Experimental investigation of modified indirect solar dryer with integrated thermal storage material for drying of dhekia (Diplazium esculentum) fern

Food product drying is a crucial stage in the preservation of crops and agricultural by-products that are used as raw materials for numerous end applications. The novelty of the study is the application of a phase change material in a solar dryer to improve the effectiveness of drying and reducing the overall drying period for drying while retaining/improving the quality parameters of the dried dhekia (Diplazium esculentum). The modified indirect thermal storage integrated solar dryer made up of a single-pass solar collector is attached with the drying chamber of 16.5 kg capacity. A thermal energy storage system prepared with paraffin wax embedded inside the drying cabinet was used. The proposed solar dryer has a thermal efficiency that is 11 ± 0.2% greater than the conventionally constructed solar dryer and reduces drying time by 40 ± 2.1%. Drying kinetic analysis of dhekia was performed, and two new drying kinetic models were proposed to predict moisture ratio. From statistical analysis, it was found that the chi square value and root mean square error value fits well for the proposed models. The anti-oxidant, total phenolic content, and total flavonoid content values of samples dried in solar dryer exhibit better results compared to fresh, tray dried, and open sun-dried samples. The developed dryer shows better results in saving drying time and quality of the product. Due to its affordability and long-term solution for drying fresh farm goods, this dryer can be very helpful to small-scale farmers.

Assessment of energy, exergy, environmental, and economic study of an evacuated tube solar dryer for drying Krishna Tulsi

In the present work, experimental studies of drying Krishna tulsi leaves in an in-house fabricated evacuated tube solar collector (ETSC) connected with an indirect solar dryer are carried out. The acquired findings are compared to those obtained from drying the leaves in open sun drying (OSD). The developed dryer takes 8 h to dry Krishna tulsi leaves; it takes 22 h in the OSD to reach a final moisture content of 12% (db) from an initial moisture content of 47.26% (db). The collector and dryer efficiencies range from 42 to 75%, 0-18%, respectively, with an average solar radiation of 720 ± 20 W/m². The ETSC and drying chamber exergy inflow and outflow vary from 200 to 1400 W, 0 to 60 W, and from 0 to 50 W,  0 to 14 W, respectively. The ETSC and cabinet exergetic efficiencies range from 0.6-4% and 2-85%, respectively. The exergetic loss of the overall drying process is estimated to be 0-40%. The drying system sustainability indices, including improvement potential (IP), sustainability index (SI), and waste exergy ratio (WER), are calculated and presented. The value of the embodied energy of the fabricated dryer is 349.874 kWh. For an expected life span of 20 years, the dryer will reduce CO₂ by 13.2 tonnes and earn carbon credits worth between 10,894 and 43,576 INR. The proposed dryer has a payback period of 0.4 years.