Energy efficiency and grain quality characteristics of cross-flow and concurrent-flow dryers

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6756346

Rodriguez, J C

An experimental and simulation study was conducted on the state-of-the-art of US on-farm and off-farm corn drying technology. Experimental data were collected on four commercial cross-flow and one concurrent-flow dryers in four Midwestern states. Each of the dryers was analyzed in depth by simulation. Energy efficiency and grain quality were employed as the criteria for dryer evaluation. Recirculation of exhaust air in cross-flow dryers was found to save as much as 30 percent of the required energy at a cost of about 10-15% on dryer capacity. Reversal of the direction of airflow in the drying section of a cross-flow dryer results in a significant decrease in the moisture content gradient of the outlet grain. Mixing the grain after partial drying in a cross-flow dryer and tempering it before final drying/cooling, further decreases this moisture gradient. The most sophisticated cross-flow dryer combines grain mixing and air recycling with an option to vary the velocity of the grain on the two sides of the individual drying/cooling columns. This design leads to energy efficiency and grain quality characteristics which rival those of multi-stage concurrent-flow dryers. The energy consumption of a differential grain speed cross-flow dryer (DGSCF) is less than 50% of that of a conventional non-recycling cross-flow model. The optimum grain speed ratio in a DGSCF dryer depends on the type of product, the initial product moisture content and the inlet air temperature; the speed ratio varies from 2:1 to 4:1 with the drying product closest to the air inlet flowing at the greater velocity. A further advantage of the DGSCF dryer is the shorter time at which the product is kept at high temperatures compared to other types of cross-flow dryers. The multi-stage concurrent-flow dryer with counterflow cooler proved to be the best of the five dryers analyzed with respect to energy efficiency and grain quality characteristics.

• OSTI ID: 6756346
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320303* -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Equipment & Processes
CEREALS
DRYERS
DRYING
EFFICIENCY
ENERGY EFFICIENCY
FARMS
GRAMINEAE
GRASS
MAIZE
MIXING
PERFORMANCE
PLANTS