پايش پارامترهاي مؤثر بر خشك شدن سبزي هاي برگي در يك خشك كن خورشيدي همرفت اجباري

Monitoring Effective Parameters of Drying Leafy Vegetables in a Forced-Convection Solar Dryer

Monitoring the effective parameters of drying crops is necessary to evaluate and determine system performance under real conditions. Hence, a monitoring system was constructed to determine the performance of a vegetation forced-convection solar dryer. Digital temperature sensors were set up in the air inlet and outlet of the collector and the air outlet of the drying chamber. A program was written using visual Basic 6 software to register sensor data and make calculations. To evaluate the dryer, experiments were carried out over eight hours between 10 am and 6 pm during the summer. Mint was used for drying in all experiments on 5Cm high trays of the dryer chamber. The results showed that the radiation energy, the heat energy absorbed by the collector and the energy required for product evaporation had linear relationships with temperature. Radiation energy increased at first and decreased later during the drying time. The results showed that the average temperature in the collector air inlet, outlet and drying chamber air outlet were 38.1°C, 54.7°C and 45.5°C, respectively. The average maximum and minimum energy efficiency were 49% and 14.7%, respectively. The average radiation energy and required energy for product evaporation were 4572.4 and 2772.2 KJ, respectively. The drying curve was Mwb= 1.827e"04857ʹ with R2= 0.945.