EXPERIMENTAL EVALUATION, SIMULATION AND OPTIMIZATION OF A COMMERCIAL HEATED-AIR BATCH HAY DRIER .1. DRIER FUNCTIONAL PERFORMANCE, PRODUCT QUALITY, AND ECONOMIC-ANALYSIS OF DRYING

This paper considers the engineering design, operation, functional per formance, product quality, and economic analysis of a natural gas heat ed-air batch hay drier that operates with an automatic bale wagon. The automatic bale wagon and a track are used for loading and off-loading stacks of alfalfa and timothy hay en masse to and from the drier. The newly developed batch hay drier has two identical drying units in a g able roof building, and each drying unit has a large axial flow fan wh ich forces about 450 m(3)/min of air by negative pressure through 22-3 2 t (a maximum of five stacks) of small rectangular hay bales placed t o dry on the perforated extended metal grate floor of the drier. Top p lenum swing-away frames, with attached polyethylene curtains, were use d for effectively sealing the vertical sides and one end of the hay st acks. Batches of hay, initially at about 25-40% moisture content wet b asis (w.b.) were successfully dried to 12-15% final moisture content i n 17-37 h at moderate drying air temperatures of 45 +/- 5 degrees C. T he drying capacity was 1.0 t dried hay/h, specific fuel consumption 26 m(3)/t, specific energy consumption 4790 kJ/kg water evaporated, and drying energy cost Canadian $5.82/t when hay was dried from an initial moisture content of 30% w.b. to a final value of 15% w.b. The hay pro duced by the drier was of high quality with an attractive green color. (C) 1996 Silsoe Research Institute