Development of a novel solar dryer with an incorporated heat exchanger

•Airflow greatly influences heat exchanger, collector, and drying performance.•The heat exchanger unit recovers 50 % of the heat for the highest tested airflow.•Flow selection is vital to achieve the optimum exchanger and collector efficiencies.•Despite variation in the performance, increasing airflow enhances the drying rate.•The highest drying rates for apple and ginger were 85 g/(h×m2) and 56 g/(h×m2) respectively.