Energy Use and Efficiency of Rice-Drying SystemsI. On-Farm Cross-Flow Dryer Measurements

. Energy use and efficiency of an on-farm, cross-flow dryer were measured by performing five tests during the harvest season of 2011 and three tests during the harvest season of 2012. Thermal energy requirements were expressed in terms of energy per unit mass water removed, by dividing the energy requirements of the burner by the total mass of water removed for each drying run. Energy efficiency was calculated as the ratio of theoretical energy requirements to the measured energy requirements. In 2011, energy requirements to dry rice ranged from 2,840 to 5,310 kJ/kg water removed, with harvest moisture contents ranging from 16.6% to 21.7%, and in 2012 from 3,730 to 5,840 kJ/kg water removed, with harvest moisture contents ranging from 17.4% to 18.2%. Thermal energy efficiencies ranged from 47% to 90% in 2011 and from 44% to 69% in 2012. The difference between drying air temperature inside the dryer and ambient air temperature as well as the amount of water removed, expressed on a per unit mass of rice dry matter, significantly impacted energy use. Equations were developed to predict energy use and efficiency as a function of these two parameters.