Drying Characteristics Of Potato Under Double-sided Needle Electric Structure Electric Field

With the advancement of science and technology,the corona discharge effect is used for food drying due to its low energy consumption.In order to increase the drying rate of the electric field,this paper proposes a research on the structure of a double-sided needle structure drying system based on previous studies.Potato is a dry material,and its drying performance is analyzed.According to the corona discharge mechanism,the discharge electrode is optimized to increase the air volume,and the ion wind speed is further increased to improve the drying efficiency.This study is of great significance for the use of electric fields in the field of drying..Firstly,the correlation between corona discharge effect and the radius of curvature of the grid electrode and the needle electrode was analyzed using Mxwell software.Through the simulation results,the structure of the drying device was further optimized to determine the needle pitch and the needle mesh pitch.It is obtained that at the same pitch,the voltage is reduced by 5kV,and the pitch of the needle net is reduced by 5mm.When the voltage is increased to 50 kv,the diameter of the corona is 13.1mm,and the system has broken down at a pitch of 10 mm.When considering the stable operation of the system,the voltage should be less than 50 kV at this time,about 40 kv is best.When the voltage is 10 kV,The diameter of the corona is small,and the system that reduces the distance between the needle nets is also easy to break down,so the voltage should be greater than 10 kv.Combined with the effect of voltage on the electric field strength,the spacing between needle nets is the best at20 mm.A single-sided and double-sided needle-structured electric field drying experiment system was set up.The drying system was experimentally studied and its drying performance was analyzed.The experimental results show that the single-sided needle-structured high-voltage electric field drying system has a significantly higher drying rate of potatoes than natural drying.With the increase of voltage,the drying rate of potatoes also increased.The drying rates under the first 10 h voltages of 10,15,20 kV were 1.5,1.7,and 2.3 times that of natural drying,respectively.At 20 h,the water ratio decreases from 1 to 0.3 at 20 kV.The drying rate under the voltage of 10,15,20 kV for the first 10 hours using the double-sided needle structure is 2.0,2.5,and 2.7 times that of natural drying,respectively.When the potato was dried under a 20 kV high-voltage electric field,the moisture content dropped to 26%,and the drying rate began to be lower than the natural drying rate.At20 h,the water ratio decreases from 1 to 0.1 at a voltage of 20 kv.The double-sided needle structure electric field drying takes less time than the single-sided needle structure drying,and only about 10 hours of drying time is required at 20 kV.The double-sided needle electric field structure drying mainly affects the speed reduction stage of the potato drying process.The moisture diffusion path and resistance are significantly reduced,thereby improving drying efficiency.Calculate the unit energy consumption.The needle-mesh structure is best near 20 kV,and the double-sided needle structure is best near 16 kv.The Midilli and Kucuk model can be selected as the best mathematical model for drying.Eight commonly used mathematical models of thin-layer drying and three statistical parameters were used to fit the drying data.The comparison showed that the Midilli and Kucuk model is most suitable for the moisture change of thin-layer potatoes under electric field drying.The discharge electrode structure was improved and the drying performance was studied.It is obtained that changing the needle electrode to the barrel electrode can increase the area of the flow field.The barrel electrode can be regarded as a combination of multiple needle electrodes and discharge at multiple points,thereby increasing the ion wind speed and increasing the air volume compared to the needle electrode.After the ring electrode is added,the flow field area of ??the corona discharge area is increased so that the electric field is superimposed,the ion wind speed is increased,and the air volume is increased.According to the calculation,the needle,the ionic wind speed and the air volume of the needle electrode structure are the smallest,and the cylinder-ring electrode structure have the largest ionic wind speed and the air volume,the ion wind speed is 1.810 m / s,and the ion air volume is2.621 L / s.The ion wind speed increased by 0.232 m / s and the ion air volume increased by 0.392 L / s.After the ring was added,the ion wind speed increased by0.310 m / s and the ion air volume increased by 0.589 L / s,indicating that the ringelectrode has an exciting effect on the electric field.The drying efficiency of the tube ring structure obtained through experiments is the highest,indicating that the drying effect is the best.In the first 10 hours,the drying rate is 1.7 of the needle electrode,1.5 of the needle ring electrode,and 1 times of the tube electrode.