Solar-biomass and dielectric drying of mace: An investigation on renewable and fourth generation drying technologies

Abstract

This study aimed to dry mace under solar and microwave assisted convective drying system to assess the quality of end products and the process sustainability. Conventionally, mace is dried under sun and solar drying conditions due to its easiness and economic feasibility. However, owing to the harvest of nutmeg during monsoon season, drying of nutmeg and mace under alternate drying methods is adopted among the farmers and industrialists. Dielectric drying reduced the duration to 41.6 % with enhanced rate of drying. Moisture diffusivity values of solar-biomass and dielectric dried nutmeg mace were 2.30 -8 m2/s and 1.72 × 10-7 m2/s respectively. Instantaneous drying efficiencies under solar and microwave modes were in the range of 26.4 – 33.4 % and 32.5 – 41.2 %, respectively. The values of economic attributes indicated the benefit cost ratio of 2.4 and 1.9 and payback period of 1.6 and 2.1 years respectively, under solar and microwave drying conditions. The sustainability index and environment destruction coefficient was determined to be 1.54 and 1.10 and 1.86 and 2.41 respectively for solar biomass and microwave drying conditions. The exergy efficiency of the solar and microwave assisted drying of mace was observed to be 18.52 and 26.74 %, repectively Techno-economic feasibility studies on solar and dielectric dried nutmeg mace suggested that solar-biomass dehydration is more economically viable than dielectric drying for the industrial scale dried mace production.