Numerical Simulation Study And Experiment Of Column Aeroponic Cultivation System

Aeroponic cultivation is a new type of soilless cultivation technology,which has the advantages of water saving and fertilizer saving compared with traditional soil culture.In this paper,a column aeroponic culture system is designed to effectively improve the growth environment of roots during crop cultivation.In this paper,the aeroponic cultivation system was used as the experimental platform,and the computational fluid dynamics(CFD)method was used to carry out the numerical simulation study and experimental verification of the temperature field of the crop root environment inside the aeroponic cultivation box.At the same time,three kinds of air circulation schemes were designed for the growth area of crops in the aeroponic cultivation box.The optimal air circulation scheme was obtained through simulation optimization design.The ventilation dead zone of the three schemes was analyzed and the numerical simulation and experimental verification of the flow field and temperature field of the leaf growth zone were carried out.The validity and accuracy of the CFD model were verified.This paper can provide reference for the change law of flow field and temperature field,internal environment adjustment and device optimization design in aeroponic cultivation box.The main research contents are as follows:(1)The current research status of aeroponic cultivation at home and abroad is analyzed.The related literatures such as soilless culture and aerosol cultivation were reviewed.Aiming at the technical defects and existing defects of the existing aeroponic cultivation equipment,a column type aerosol culture system was designed.The system mainly includes two parts:aerosol cultivation facilities and environmental parameter collection system,which solves the problems of spray time interval,nutrient solution temperature regulation and environmental parameter collection and monitoring in aeroponic cultivation process.(2)The effects of droplet temperature change on the root growth of lettuce in the aeroponic culture chamber were studied.The temperature and spatial distribution of the temperature inside the aeroponic cultivation box and the roots of lettuce were studied after atomization of nutrient solution at different temperatures.The CFD was used to simulate the root temperature environment of the crop inside the aerosol cultivation box,and the CFD three-dimensional model of the temperature field inside the aerosol cultivation box wasestablished.(3)Taking the root of lettuce as an example,the numerical model was verified by experiment.The results showed that the maximum error value range of the simulated and measured values of the temperature inside the aeroponic cultivation box and the roots of the lettuce was less than 11.05%,the error range of the single measurement point was less than2.01 ℃,and the average relative error was less than 3.53%.The root error RMSB is 0.71 ℃,and the established CFD model is basically consistent with the temperature variation law inside the aeroponic cultivation box and around the roots of lettuce.At the same time,it was found that the ambient temperature of the aeroponic culture chamber was 19 ℃,and the optimum temperature range of the nutrient solution was 18 ℃-20.5 ℃.(4)The distribution of flow field and temperature field in the growth area of crops in the aeroponic cultivation box was studied.The important effects of air flow and temperature on environmental regulation and crop growth in aeroponic cultivation box were discussed.The CFD model under different airflow circulation modes was constructed,and the airflow circulation mode in the cultivation box was optimized.Three kinds of air circulation schemes were compared: from the top surface to the side,the side into the top surface,and the side into the side.The optimal airflow circulation scheme is obtained by numerical simulation method: the side into the top surface.The numerical model was tested and verified.The result shows that the average relative error and root mean square error of the simulated and measured values of temperature and wind speed in the aeroponic cultivation box are 3.9%,0.86 ℃,3.5%,and 0.26 m/s,respectively.