Replicated factorial investigation of residence-time control and moisture loss in an adjustable vibratory hot-air dryer for olive pomace

Abstract This study examines whether adjustable shelves and outlet shutters control solids transport in a prototype vibratory hot-air dryer for olive pomace. A replicated $$2^{4}$$ design combined two levels of each shelf inclination and shutter opening: 16 settings with four runs each. Residence time and recovered mass were recorded at 65 $$^{\circ }$$ C and 1190 rpm; velocity was derived from the fixed path. Raising shelf 2 shortened residence time by 416.4 s (95% CI: $$-419.2$$ to $$-413.6$$ s), the largest transport effect. Shutter 2 gave the largest recovered-mass effect ( $$-0.0848$$ kg; 95% CI: $$-0.0892$$ to $$-0.0803$$ kg). Factorial regression predicted held-out residence time better than a compact ANN, whereas the ANN gave the lower recovered-mass error. With inlet moisture recorded at 55%, moisture loss and outlet moisture (34.8–53.3% wet basis) were obtained gravimetrically from the combined product and cyclone-fines mass. The novelty lies in the replicated separation of four geometric adjustments and their condition-grouped predictive comparison.