AERATION STRATEGY SIMULATIONS FOR WHEAT STORAGE IN THE SUB-TROPICAL REGION OF NORTH INDIA
Ambient aeration is typically used in temperate climates to preserve grains by cooling, preventing moisture migration, and maintaining temperature as low and uniform throughout the grain mass as possible. However, the climatic factors for wheat bulk storage in the sub-tropical climate of north India are challenging for the grain preservation process. Low relative humidity with high temperature during daytime and high relative humidity with low temperature during nighttime is the common phenomenon. Five years of weather data were analyzed using the modified Chung-Pfost EMC equation for wheat. Fifteen different aeration strategies were formulated based on the weather data during the maintenance period (June to September) and cooling period (October to March). Strategies were selected based on combinations of the following parameters: temperature control; EMC control; 1 h, 2 h, or 4 h morning and/or evening aeration; and 0.11, 0.34, and 0.67 m3 min-1 t-1 airflow rate. These 15 aeration strategies for the sub-tropical weather conditions of north India were studied using the 2D PHAST-FEM model developed at Purdue University. The initial grain temperature and moisture were assumed as 27°C and 12% (w.b.), respectively, based on typical harvest conditions. Dry matter loss (DML), insect development, fan run hours, and average grain temperature and moisture content for these aeration strategies were quantified based on weather data from 2000-2001 to 2004-2005. Aeration strategies were selected based on the optimum combination of low values of DML, insect development, grain temperature, moisture content, and fan run hours during both the maintenance and cooling periods . The best strategy was to operate fans 4 h during the morning and evening with an airflow of 0.11 m3 min-1 t-1, with EMC control but without temperature control during the maintenance period and with both EMC and temperature control during the cooling period (strategy 13).