RESISTANCE TO AIRFLOW THROUGH SWEET POTATO AERIAL VINE COMPONENTS

Abstract

Designers of forced air handling systems require data on resistance to airflow for accurate selection of fans and mathematical prediction of pressure drop and airflow patterns. In this research, resistance to airflow of sweet potato leaves and chopped sweet potato aerial vines dried in an experimental cabinet dryer was measured to determine the effect of airflow rate, moisture content and bulk depth. Five levels of moisture contents (88.7%, 74.7%, 52.9%, 26.8%, and 11.0% w.b.) for sweet potato leaves and (88.1%, 69.1%, 52.2%, 35.0%, and 12.2% w.b.) for chopped sweet potato aerial vines, respectively, and four levels of bulk depths (0.30, 0.45, 0.60, and 0.75 m) were investigated at airflow rates ranging from 0.0206 to 0.2342 m3 s-1 m-2. Results indicated that airflow, moisture content, and bulk depth have significant (P < 0.01) effect on airflow resistance of sweet potato leaves and chopped sweet potato aerial vines. Equations that relate pressure drop to airflow rate, moisture content, and bulk depth were developed based on the Hukill and Ives (1955) equation through the implementation of empirical “de-rating” factors and the coefficients obtained by regression analysis. The developed models provided a good fit to the experimental pressure drop data obtained in the range of conditions investigated. Also, comparison of the pressure drop data in this study with marigold flowers cited in the literature shows that the resistance to airflow for both sweet potato leaves and chopped sweet potato aerial vines was lower than that of marigold flowers. The pressure drop curves for sweet potato leaves however had a steeper slope than the marigold flowers. Bulk density which varied from 29.57 to 112.63 kg m-3 for sweet potato leaves and 83.99 to 317.23 kg m-3 for chopped sweet potato aerial vines was significantly affected by moisture content