Drying mathematical modeling and the effect of different atmospheric conditions on the efficiency of the hybrid-solar dryer

This paper presents the thin layer drying behavior of Dill by a solar hybrid dryer. Experiments were carried out at the air temperatures of 40ºC, 50ºC, 60ºC, 70ºC and air velocity of 1m/s, 1.5 and 2 m/s. 5 different thin layer drying models were fitted to experimental data. The high values of coefficient of determination and the low values of reduced chi-square and root mean square error indicated that the Aghbashlo et al. model could satisfactorily describe the drying curve of Dill. According to resultsThe drying rate increased with an increase in the drying air temperature and drying air velocity. Also the effect of the air velocity on the drying time at a low temperature is greater than that at a high temperature. Based on the results, the mean values of increasing in air temperatures by solar radiation for cloudy, partly cloudy and sunny conditions were 11.76, 15.89 and 19.11ºC, respectively.