The Stress Engineering Process Technology Group maintains a temperature and humidity controlled wind tunnel in our Cincinnati testing lab. This facility is used to evaluate drying rates of manufactured products with the goals of reducing cycle time, improving dimensional control, and increasing energy efficiency. Typical applications range from drying wood-pulp products, woven and non-woven fabrics, surface coatings, and dehydrated foods.
The photograph below shows the laboratory-scale wind tunnel designed and built by Stress Engineering for the Drying Laboratory. The wind tunnel provides a controlled environment, with temperatures in the 75-200 oF range and relative humidity from 10 to 90%. The test section velocity can be varied from 100 to 4000 fpm to simulate rapid convective drying.
The photograph below shows a mosquito-repellant coil in the test section of the drying tunnel while the adjacent graph shows the results of a drying test performed on the coil. The mosquito coil is composed primarily of wood pulp and is being dried in a high-temperature cross flow of air. The results show a characteristic two-phase drying profile, beginning with a constant-rate primary phase when the product is saturated and concluding with a falling-rate secondary phase as the mosquito coil dries beyond the saturation point.
