Drying performance analysis of a batch type fluidized bed drying process for corn and unshelled pistachio nut regarding to energetic and exergetic efficiencies

A batch type fluidized bed dryer is designed and constructed in order to investigate drying performance of a batch type fluidized bed drying process of corn and unshelled pistachio nut regarding to energetic and exergetic efficiencies. A series of experiments is carried out for the purpose in the covered range of 100 g ⩽ mp ⩽ 300 g, 50 °C ⩽ T ⩽ 75 °C, 6.87 m/s ⩽ Um ⩽ 10.86 m/s and 47632 ⩽ Re ⩽ 75296. An increase in particle mass is found to cause an increase of drying time. On the other hand, an increase in drying air temperature and drying air velocity result in a decrease of drying time. The experimental results in terms of energetic and exergetic efficiencies are compared with the available ones in the literature by means of the previously proposed model of the authors. There is a good conformity between the present data and available data in the literature with a mean deviation of ±14% for energetic efficiency during drying process of corn. However, the deviation is raised to ±37% for energetic efficiency during drying process of unshelled pistachio nut, diverging from Eq. (9) which was previously proposed for corn drying. It can be deduced that both energetic and exergetic efficiencies are strongly dependent on air mass flow rate, particle mass and moisture content of particle to be dried and also ambient temperature.