Research On Ventilation Simulation And Optimization Of Plant Factory With Artificial Light Based On CFD

As an advanced form of modern agriculture,plant factory with artificial light is rapidly developing worldwide due to its controllable environment,safety and health,short production cycle,and enable plants to maintain high quality production at all times.In plant factory with artificial light,forced convection caused by ventilation and air circulation can control the growing environment and maintain a uniform climate.In this paper,crop-free plant factory with artificial light was taken as the research object,and CFD(computational fluid dynamics)was used to build three-dimensional plant factory models to simulate and explore the distribution of air flow field and temperature field in plant factory under different ventilation modes.1.Three cases of air ventilation and circulation systems were designed to improve velocity and temperature value and their uniformity.CFD(computational fluid dynamics)was applied to create a three-dimensional model,the whole plant factory was divided into grids and simulated.CFD model was validated through comparison of experimental data of the distribution of air flow and air temperature in a plant factory.The maximum absolute error,average relative error and root mean square error of wind speed and temperature are 0.12m/s,1.1?;11%,4%;0.18 m/s,1.3?,respectively,which showed that simulation was accurate.Four cases were studied and compared in this study.Case0:control treatment,conventional air supply with upper(in the ceiling)air inlet and both side wall outlets;Case1:one side wall inlet,the other side wall outlet;Case2:one side wall inlet,the other side wall and upper outlet;Case3:both sides inlet,upper outlet.Results showed that Case1~Case3 could improve velocity and temperature value and their uniformity compared with Case0.By comparing wind speed and temperature value of plant canopy surface,Case1 increased average wind speed by 0.51m/s,reduced coefficient of variation(CV)by 17%,reduced average temperature by 0.5?,was the best air circulation system.2.Two kinds of ducted ventilation modes were set for plant factory with artificial light.Case1:two sides wall inlet,upper wall outlet,and the airflow enters inside the pipes under the pressure of the fans at bottom of the pipes,and flows into the cultivation shelves through the sidewall holes.Case2:the airflow enters the pipes directly from the bottom of the pipes and flows into the cultivation shelves through the sidewall holes.The CFD software was used to simulate and compare the two cases,the results showed that when the pressure jump value in case1 was set 150Pa,and the inlet velocity was set3m/s in case2,the air velocity value was the most suitable in the canopy surface area;In contrast,case2was more optimum than case1 in air velocity in the canopy surface area and was more energy-efficient.3.A plant factory with artificial light was designed with a cultivated area of 80.5m~2,and four air flow circulation patterns were designed for it,the upper inlet,sides outlet(less outlets);the sides-inlet,upper outlet(less inlets);the upper inlet,sides outlet(more outlets),the sides-inlet,upper outlet(more inlets).The CFD software was used to simulate and compare the four air circulation patterns.The results showed that the maximum average air velocity of the canopy surface area was 0.90 m/s in the sides-inlet,upper outlet(more inlets)mode,and the percentage of>1.0m/s was the highest.In case1,percentage of velocity value between 0.3 and 1.0m/s was the highest,and the uniformity was the best.In the upper inlet,sides outlet air circulation mode,changing the number of outlets would not make the results significantly different.In the sides inlet,upper outlet air circulation mode,changing the number of air inlets had a great influence on the airflow in plant factory.