Energy and exergy analyses of drying medicinal herb in a novel forced convection solar dryer integrated with SHSM and PCM. (June 2021)

• Record Type: Journal Article
• Authors: Bhardwaj, A.K.; Kumar, Raj; Kumar, Sushil; Goel, Bhasker; Chauhan, Ranchan
• Is Part Of: Sustainable energy technologies and assessments. Volume 45(2021)
• Publication Date: 2021-06
• Subjects: Dehydration Rate -- Forced Convection -- Moisture Content -- Rehydration Capacity -- Thermal Energy Storage; Renewable energy sources -- Periodicals; Energy development -- Technological innovations -- Periodicals; Electric power production -- Periodicals; Energy storage -- Periodicals; 333.79
• DOI: 10.1016/j.seta.2021.101119
• Languages: English
• ISSNs: 2213-1388

Abstract

Highlights: A novel forced convection solar dryer was developed for drying medicinal herb ( Valerian rhizomes). Simultaneously, SHSM and PCM were used as a thermal energy storage material to improve effectiveness of drying system. The established setup facilitated in saving 288% of the dehydrating time of Valerian rhizomes as compared to the traditional shade drying. Quality of dried Valerian rhizomes were much better than the traditional drying. Exergy efficiencies of the solar dryer and drying system were computed. Conclusions were drawn based on energy and exergy efficiency, and energy consumption during drying process. Abstract: This article examined the performance of a low cost, economically viable and a novel forced convection solar drying system. To control the thermal fluctuations during the day-night drying process, solar air collector (SAC) was equipped with sensible heat storage medium (SHSM) while, drying unit contained paraffin RT-42 as a thermal energy storage (TES) medium. The experiment was conducted considering a sample size of 9.0 kg of Valerian rhizomes. The rhizomes were dehydrated to saturation value of 9% from preliminary moisture content of 89% on wet basis and took 120 (216) hours with (without) use of TES. The performance evaluation of each element of the dehydrating system was carried out on the basis of energy and exergy analyses. The mean values of energy and exergy efficiencies of SAC without (with) TES were computed to be 9.8(26.10) % and 0.14(0.81) % respectively. The overall drying rate without (with) applying TES was 0.028(0.051) kg/hour. The exergy efficiency of the drying unit was assessed to vary from 3.7% to 75.15% with a mean value of 30.28%. The specific energy consumption (SEC) of the rhizomes and the overall efficiency of the drying system were 11.33 kWh/ kg of moisture and 10.53%, respectively.