Abstract
Solar PV system powered mixed-mode solar tunnel dryer (STD) for drying potato chips was studied. The STD was equipped with axial dc fan and flat plate solar air collector to enhance the thermal performance by maintaining a reasonable high temperature inside the drying chamber. The STD performance was evaluated without load and with load; and without and with using thermal curtain above potato slices during sunny days. Different airflow rates (2.1, 3.12 and 4.18 m(3)/min) and pre-treatments for potato slices were investigated. The PV powered STD exhibited the ability to produce chips with safe moisture level within 6 and 7 h for without and with using thermal curtain, respectively at airflow rate of 3.12 m3/min. The frying time of potato chips was shortened to be only 15 s. The best chips color was achieved with 1% sodium meta-bi-sulphite with using black thermal curtain above slices. Predicted and experimental moisture ratio of chips using developed STD were compared through several thin-layer drying models. The highest drying efficiency of 28.49 and 34.29% was recorded at airflow of 0.0786 kg/s in case of without and with using thermal curtain, respectively. The developed STD provides chips in good quality and suitable for rural areas. (C) 2017 Elsevier Ltd. All rights reserved.