Experimental investigation of the performance of a novel solar dryer for drying medicinal plants in Western Himalayan region

• Published in: Solar energy Vol. 177; pp. 395 - 407
• Main Authors: Bhardwaj, A.K., Kumar, Raj, Chauhan, Ranchan
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.01.2019; Pergamon Press Inc
• Subjects: Convection; Drying; Energy efficiency; Enthalpy; Essential oils; Exergy; Forced convection; Gravel; Heat storage; Herbal medicine; Indirect solar dryer; Medicinal plants; Moisture content; Paraffin; Paraffins; Phase change materials; Power efficiency; Rehydration; Rhizomes; Scrap iron; Sensible heat; Shade; Solar collectors; Solar dryers; Solar energy; Thermal energy; Thermal energy storage; Thermal storage; Thermodynamics; Tubes; Valeriana Jatamansi; Water content; Thermal energy storage; Valeriana Jatamansi; Indirect solar dryer
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2018.11.007

•Sensible and latent heat storage has been incorporated to solar drying system.•Better product quality has been achieved wi efficient energy conversion.•Performance has been investigated in terms of exergy efficiency.•Biomedical evaluation of the product has been performed.•The drying time of the product has been decreased due to continuous drying process. This paper presents the experimental investigation of indirect forced convection solar dryer integrated with sensible heat storage material (SHSM) and phase change material (PCM) in meteorological environment of Himalayas (latitude 30.91 °N). The iron scrap mixed with gravel is placed on absorber plate and copper tubes comprising of engine oil have been used as SHSM in the solar collector. The Paraffin RT-42 as a PCM has been used in the drying chamber. Experimentations of Valeriana Jatamansi (a medicinal herb) drying have been conducted and its moisture content reduced from initial value of 89% to 9%. Using SHSM and PCM simultaneously the overall drying rate observed 0.051 kg/hr which was almost double as compared to 0.028 kg/hr and 0.018 kg/hr with no use of thermal storage medium and traditional shade drying, respectively. The drying time to reach the saturation level of 9% was recorded as 120 h in comparison to 216 and 336 h, respectively and the dried rhizomes of good quality in terms of essential oil and bio-medical compounds are obtained. From the experimental results rehydration capacity and total Valepotriates were found 7.11 and 3.47% as compared to 6.18 and 3.31%, respectively in case of traditional shade drying. The solar collector without SHSM possess an average energy and exergy efficiency 9.8% and 0.14%, respectively. The respective energy and exergy efficiency achieved with SHSM are 26.10 and 0.81%.