Simulation and optimization of energy systems for in-bin drying of canola grain (rapeseed)

Abstract

Energy utilization systems optimization and management strategies for in-bin drying of canola were investigated by using a validated computer simulation model and typical weather data for a prairie location in North America. The use of different energy systems, including natural gas, propane, electricity, solar energy, and combined natural gas and solar energy for drying grain within 15 days with airflow rates of 0.5–2 m 3/min t, initial grain moisture contents of 13, 16 and 19%, and three harvest dates in August, September and October, was simulated for 10% and 8% moisture contents average-dry and through-dry policies. The drying systems were optimized by considering the total annual cost of a drying system within set bounds of drying time (⪕15 days) and spoilage index (SI < 1.0). Continuous fan operation with 1.5–2 m 3/min t ambient air with about 9–26 MJ/t fan energy consumption was required to dry canola grain to 10% and 8% average-dry and through-dry moisture contents in 15 days or less August at 19% initial moisture content or less. Supplemental heat, by raising the ambient temperature by 5–10°C, maintaining the plenum temperature at 20°C and solar heating, must be applied to successfully dry the product in September and October. Solar heating for drying was found to be more cost effective than other supplemental heat systems provided a well designed flat-plate solar collector for air heating can be found for use in locations with good solar energy availability. Heating the drying air with natural gas or propane was the cost effective for situations where the use of conventional energy systems is preferable to renewable energy sources in grain drying operation.