Effect of temperature and air velocity on drying kinetics and organo essential oil extraction efficiency in a hybrid dryer

This paper presents the thin layer drying behavior of Nepeta L. 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. 8 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 Nepeta L.. 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. According to the results analysis of variance the effect of air temperaturedrying and air drying rate at probability level 1 percent and the Interactive effects of temperature and air velocity, was not significant, and the highest amount of essential oil related to a temperature of 40 ° C and air velocity of 1.5 m/s was achieved with approximately 0.54 cc and increasing the temperature from 40 ° C to 70 ° C Significantly decreased the amount of essential oil.