Research And Development Of Strawberry Environment Monitoring System In North Solar Greenhouse Based On Accumulated Temperature Theory And CFD Method

Strawberry is an important economic crop in China.The production method is mainly planted in the greenhouse.Scientific and accurate monitoring of the growth environment of strawberries in the greenhouse is of great significance for improving strawberry yield,perception and quality.At present,the environmental monitoring of strawberry greenhouses in the north is mainly a traditional method of manual measurement and control.The labor input is large,and the temperature distribution in the greenhouse is difficult to control,and the growth environment of strawberries is unstable.Therefore,based on the climatic characteristics of the northern region,this study combines the theory of accumulated temperature theory,computational fluid dynamics(CFD)and Internet of Things technology to design a strawberry greenhouse solar greenhouse monitoring system to improve the strawberry in the greenhouse.The production environment can effectively solve this problem.The main contents and results of this research are as follows:(1)In this study,based on the theory of accumulated temperature theory,six accumulative temperature models based on the two-basis plant growth linear hypothesis A and the three-basis optimization hypothesis B were studied,respectively,for the flowering period,the initial fruit period,the fruit turning period and the strawberry growth period.The reference value,prediction accuracy,stability and model effect of the four-stage accumulated temperature model during the fruiting period were evaluated.In the flowering stage and the initial fruit stage of strawberry,the time-accumulation model based on the three-basis optimization hypothesis B is better.In the red-phase stage of strawberry fruit,the time-accumulation model based on the two-basis linear hypothesis A is better.The coefficient of determination,root mean square error,coefficient of variation and standard deviation were: flowering period,0.9166,5.97,10.36%,4.99;initial fruiting period,0.9431,6.53,10.43%,5.82;fruit turning period,0.9184,5.49,10.3%,4.62;fruiting period,0.9439,8.68,10.77%,7.51.Using these two accumulated temperature models as the environmental temperature control model of strawberry is conducive to improving strawberry yield,perception and quality.(2)Based on the Computational Fluid Dynamics(CFD)method,this study uses the CFD series software to establish a three-dimensional steady-state model of the solar greenhouse,and simulates the temperature field distribution of the greenhouse in the natural ventilation.The maximum error between the simulation result and the actual value is 7.172%,the minimum error is 0.354%,and the majority of the point error is within 5%.The model effect is better.The ambient temperature distribution in the greenhouse is roughly symmetrical with a vertical plane at a length of 30 meters,and at a height of 1.0 m,the temperature range is in the range of 15-20 degrees,and most of the temperature values are near the optimum temperature of 18 degrees for the growth of the strawberry..The temperature points A(15,1,4)and B(30,1,4)in the greenhouse are used as temperature monitoring points for the solar greenhouse monitoring system,which can effectively reflect the ambient temperature of strawberry growth in the solar greenhouse.Using elevated substrate cultivation techniques,the height of the strawberry culture medium is adjusted to 1.0 m,which is beneficial to improve the utilization of temperature in the greenhouse,reduce energy consumption and increase strawberry yield,perception and quality.(3)Based on the Internet of Things technology,this study uses industrial-level programmable human-machine interface and configuration software to design the northern strawberry solar greenhouse environmental monitoring system to realize real-time online monitoring,alarm linkage and remote operation of the solar greenhouse environment during strawberry production.Control,statistical reports and other functions.There is no failure during the operation of the system,and it can effectively monitor and control the environment in the greenhouse,especially the temperature.Compared with traditional labor,the yield of strawberry is significantly improved after applying the system.The strawberry fruit is fuller,the shape is more round,the color is bright,the gloss is good,the taste is sweet and nutritious,and the economic benefit of strawberry production in the northern solar greenhouse is significantly improved.