| Aeroponics cultivation is a brand-new cultivation mode based on engineering technology,biotechnology and computer control technology,the core of which is to hang the plant root system inside the closed device and provide a good water fertilizer temperature environment to the root zone in time.Its root zone is the main occurrence site and reaction interface of plant aeroponics cultivation environment control,and it is also the core part of cultivation environment control,which directly determines the success or failure of aeroponics cultivation.Due to the characteristics of the small environment of hanging air and small growth space in the root zone of aeroponics cultivation plants,compared with the regulation of the whole space environment and the regulation of cultivation medium of traditional facilities cultivation,from the point of view of energy saving and efficiency,it is more direct and efficient to regulate the environment of the root zone of aeroponics cultivation,and can obtain higher biological yield with smaller energy and resource input.However,china lacks the intelligent supporting equipment and control means of economical and effective aeroponics cultivation,which leads to great restrictions on its popularization.In order to promote the development and application of aeroponics cultivation technology,this paper,based on the purpose of saving energy consumption,improving the utilization rate of nutrient liquid and improving cultivation efficiency,aims at two kinds of atomization methods in the field of aeroponics cultivation: pressure spray cultivation and ultrasonic atomization cultivation,and conducts the key technical research on environmental regulation in the root zone of aeroponics cultivation.The main studies are as follows:(1)A test platform for environmental regulation and control of the root zone of the aeroponics cultivation system of pressure spray cultivation and ultrasonic atomization cultivation was developed,and a aeroponics cultivation control system was set up,Based on these,the relevant research on the key technologies of environmental regulation in plant root zone of Aeroponics cultivation system was carried out.(2)In view of the technical field of pressure spray aeroponics cultivation,the environmental control strategy of the temperature of nutrient liquid and spray-coupled pressure spray cultivation plant root zone was proposed.The distribution and test of the temperature field in the root zone of the pressure spray cultivation device were carried out,the temperature field in the root zone was numerically simulated by CFD method,a three-dimensional model of the root temperature was constructed,and the temperature change and spatial distribution law of the nutrient liquid of different temperatures were obtained after atomization.Taking the prismatic pressure spray cultivation device as an example,the test of lettuce aeroponics cultivation with the temperature of nutrient liquid and spray frequency coupling was carried out,and the results showed that under the low temperature environment,the growth potential of lettuce cultivated by the experimental group of nutrient liquid heating treatment and combined with spray control was much greater than that of the control group without treatment,the fresh weight mass of its leaves could be increased by more than 120%,the fresh weight of the root was increased by about 50%,and the temperature of nutrient liquid and spray frequency were significantly controlled.(3)In view of the technical field of ultrasonic atomization cultivation,a model of root nutrient liquid droplet settlement and temperature change model of root zone during the atomization of ultrasonic atomization cultivation device was established,and a combination control strategy of spray frequency of ultrasonic atomization cultivation lettuce was proposed.Using the method of four-factor five-level(1/2 implementation)secondary universal rotation combination design test,the study of the temperature change law of the fog droplet in the plant root system after ultrasonic atomization and the temperature change law of the root region in the cultivation device was carried out,the corresponding regression equation model was established and analyzed,and the effect of the four factors of atomization,wind speed,ambient temperature and atomization time on the temperature change and root drop of the supersonic fogging device was discussed.Using CFD method,numerical simulation was carried out on the root temperature environment after the atomization of ultrasonic fog-cultivation device was stopped,a three-dimensional model of the root temperature field was established,and the temperature change and distribution law of the root region were obtained.According to the model of the law of fog droplet settlement of plant root system and the temperature change model of root zone,the spray frequency combination control strategy of different growth stages of ultrasonic atomized cultivation lettuce was proposed,and the comparative test of lettuce cultivation was carried out,and the test results showed that the test group‘s fresh weight in the leaf and the fresh weight of the root were 3.1g and 0.44 g higher than the control group,which had slightly better growth and energy saving of about 6.25%,which had a positive effect on the popularization and application of ultrasonic atomization cultivation.(4)The regulation and spray control of nutrient water fertilizer in aeroponics cultivation were studied,and an automatic control algorithm for the supply of nutrient liquid spray based on adaptive fuzzy neural network was proposed.Using multi-sensor fusion technology,the environmental factors of the root zone of aeroponics cultivation were merged with the environmental factors of the greenhouse,and the automatic control prediction model of nutrient liquid supply spray was established by the environmental parameters,root temperature,nutrient liquid temperature and actual spray frequency.The simulation test results show that the maximum absolute error between the true and predicted value of the spray duration is less than 3s,the relative error is less than 7%,the true value of the spray idle time and the relative error of the forecast value is less than 3%,the prediction effect is good,and the real-time monitoring of the environment of the Aeroponics cultivation root zone,the on-line nutrient liquid supply adjustment and variable frequency spray control can be realized.(5)The cultivation test of different structural aeroponics cultivation devices was carried out,the better structural forms of pressure spray cultivation devices and ultrasonic atomization cultivation devices were discussed,and the effectiveness of environmental control in the root zone of aeroponics cultivation system was verified.In order to further verify the feasibility and stability of the system,the study of lettuce cultivation was carried out on the prismatic pressure spray cultivation device,the A-type pressure spray cultivation device,the ladder-form pressure spray cultivation device,the flat ultrasonic atomization cultivation device and the pipe-type ultrasonic atomization cultivation device respectively,and the hydroponic device as a control group was compared,and the differences in the growth index of different devices for the cultivation of lettuce were compared,and the main indicators of the growth status of raw vegetables were screened.The aeroponics cultivation device with better cultivation effect was obtained.The results showed that the pressure spray cultivation effect was better than hydroponic,while the flat-type cultivation effect was better than hydroponic,but the pipe-type cultivation effect was lower than hydroponic.Cultivation experiment provides theoretical basis and technical support for the further development and application of aeroponics cultivation mode. |
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