Red Jujube Dryer Control System Design Based On LabVIEW And Drying Process Research

Red jujube mainly rely on the traditional hot air drying process of the accumulation of experience,which lacks a system research. The control system of red jujube dryer gradually cannot meet the needs of the new process of hot air drying. Therefore, in this article, the orthogonal experiment on the drying process parameters of Hotan Jun jujube that moisture content is 62.64±2% is studied on the basis of the drying process of traditional drying room. According to the demand of the drying process, this study designed the red jujube dryer control system on the basis of LabVIEW.(1) Making use of the developed air drying device to carry out the orthogonal experiment on the drying process parameters of Hotan Jun jujube that moisture content is 62.64±2%. Through the analysis of test results, this study shows that hot air temperature have a significant effect on the drying time, Colour and lustre of jujube's peel, the brightness of peel, the degree of shrinkage, and the amount of the precipitation of sugar. The humidity of hot air only have a significant effect on the precipitation of the amount of sugar. The speed of hot air only have a significant effect on the brightness of jujube peel. The order of three factors that influence dry jujube quality is the temperature, wind speed, humidity. The optimal parameters of Jun jujube drying process are as follows: temperature of 55?, humidity of 60%, wind speed of 0.25 m/s. In combine with the traditional drying process of drying room, this study obtains a better Jun jujube drying process curve.(2) According to the requirements of Jun jujube drying process and combine with the working principle of cross-flow layered dryer, the author designs and builds the hardware circuit of the control system of LabVIEW and completes the selection of acquisition card, relay and sensor. The author designs the electric schematic diagram of the hardware circuit and assembles the power distribution cabinet.(3)The LabVIEW program of the control system is designed, according to the requirement of the red jujube drying process and combining with hardware circuit. The front panel and block diagram of the signal acquisition, analysis and display of temperature, humidity and wind speed, and the control of heating pipe and return air valve have been designed. The front panel and block diagram that can realize automatic heating, heat preservation and cooling according to the require of drying process have been designed. The front panel and block diagram of temperature, humidity and wind speed data regular preservation and the historical data curve shows have been designed. The front panel and block diagram program of blower and material hoist crane and six into/out of the wind channel realize five kinds of working mode timing to switch have been designed. The external hardware circuit has been designed.(4)For the cross-flow layered dryer for no-load test. The experiment proves that the Lab VIEW control system of dryer can realize all the designing function. All the parts of the dryer can work coordinately under the control of the control system of the Lab VIEW. Drying machine can provide uniform hot air temperature and wind speed. The hot air circulation system of drying machine work stably, meanwhile return air valve can open and close according to the humidity requirements.