Sustainable Solar Drying of Brewer´s Spent Grains: A Comparison with Conventional Electric Convective Drying

JUAN PABLO CAPOSSIO; MARÍA PAULA FABANI; ANDRÉS REYES URRUTIA; RODRIGO TORRES SCIANCALEPORE; YIMIN DENG; JAN BAEYENS; ROSA RODRIGUEZ; GERMÁN MAZZA

PROCESSES

MDPI - Multidisciplinary Digital Publishing Institute

Lugar: Basel; Año: 2022 vol. 10 p. 1 - 18

2227-9717

The spent grains from microbreweries are mostly formed by malting barley (or malt) and are suitable for a further valorization process. Transforming the spent grains from waste toraw material, for instance, in the production of non-traditional flour, requiresa previous drying process. A natural convection solar dryer (NCSD) was evaluated as an alternative to a conventional convective electric dryer (CCED)for the dehydration process of local microbrewer s spent grains. Two types of brewer s spent grains -BSG- (Golden Ale and Red Ale) were dried with both systems and sustainability indexes, specific energy consumption (eC), and CO2 emissions were calculated and used to assess the environmental advantages and disadvantages of the NCSD. Then, suitable models (empirical, neural networks,and computational fluid dynamics) were used to simulate both types of drying processes under different conditions. The drying times were 30_85 min (depending on drying temperature, 363.15 K and 333.15 K) and 345_430 min (dependingon the starting daytime hour at which the drying process began) for the CCED and NCSD, respectively. However, eC and CO2 emissions for CCED were 1.68 · 10-3_1.88 · 10-3 (kW h)/kg and 294.80-410.73 kg/(kW h) for the different drying temperatures. Using NCSD, both indicators were null, considering this aspect as an environmental benefit.