Development and Experiments on a Batch-Type Solar Roaster—An Innovative Decentralized System for Coffee Roasting

About 70% of the harvested coffee is exported to industrialized nations for value addition due lack processing and logistic facilities in developing producer countries, thus leaving behind a marginal economic return growers. This research was conducted investigate roasting capacity an innovatively developed batch-type directly solar radiated system decentralized using energy. Central composite rotatable design (CCRD) employed experiments optimize process. Experimental results revealed that with average direct normal irradiance (DNI) 800 W/m2, roaster capable batch 2 kg beans 20, 23, 25 min subjected light roasts, medium dark respectively at drum speed two revolutions per minute (rpm). The has roast 28.8–36 depending on conditions clear sunny day DNI ranging from 650 850 W/m2. thermal efficiency during determined be 62.2%, whereas corresponding roast, found 97.5%, 95.2%, 91.3%, respectively. payback period unit estimated 1038 working sunshine hours, making it viable commercialization.