Investigation of drying kinetics in the cabinet type drying system and the energy-exergy performance analysis of the dryer

In this thesis, a closed loop and cabinet type convective drying system is designed. This system consists mainly of wire mesh drying cabinet, cooling-dehumidifying section and heating section. In this system, 100 grams of apple, apricot and potato samples were dried. Drying process was performed under the following conditions. Drying air velocities: V1=0,2 m/s, V2=0,3 m/s, V3=0,4 m/s, V4=0,5 m/s, V5=0,6 m/s, V6=0,7 m/s and drying air temperatures:T1=30 ºC, T2=40 ºC, T3=50 ºC, T4=60 ºC, T5=70 ºC. The raw data obtained from the experiment were processed and parameters of drying kinetics were calculated with the help of these data. With the help of the calculated data, optimization studies were performed in MATLAB program by using the most common Drying Models in the literature. As a result of this study, the best model and drying conditions for the products were determined by examining R2 and RMSE values. These models and drying conditions were determined as Midilli et al., V5 = 0.6 m / s, T2 = 40 ºC: for apples; Verma et al., V3 = 0.4 m / s, T3 = 50 ºC for apricot; Midilli et al., V5 = 0.6 m / s, T2 = 40 ºC for potatoes. Considering the models that give the best results for the products and optimum drying conditions, the following results were obtained: For apples; MR = 0.319, DR = 0.023 m/s, Deff = 4.73x10-10 m2/s; for apricot; MR = 0.633, DR = 0.022 m/s, Deff = 1.26x10-10 m2/s, for potatoes; MR= 0.273, DR = 0.016 m/s, Deff = 9,82x10-10 m2/s. In addition to the drying kinetics study, energy-exergy analysis of the convective drying system was performed. Energy-exergy results for the drying cabinet, considering the models that give the best results for the products and optimum drying conditions, are as follows: For apples; SMER = 67.93 g-water/kW-h, COP = 14.65, COPEx, = 0.89, Exloss = 0.110 kW, for apricot; SMER = 39.41 g-water/kW-h, COP = 9.77 COPEx, = 0.83, Exloss = 0.355kW, for potatoes; SMER= 70.18 g-water/kW-h, COP = 14.56 COPEx, = 0.86, Exloss = 0.00064 kW. Keywords: Drying kinetics, Energy-exergy analysis, Mathematical modeling