CFD Numerical Simulations Of Temperature And Airflow Distributions Inside Glasshouse

The cooling effects of forced ventilation of Venlo-type greenhouse with and without tomato crop were experimentally studied in summer.Three-dimensional CFD model for a Venlo type greenhouse with and without tomato crop under forced ventilation was respectively established based on the experimental date,using the computational fluid dynamics(CFD) Fluent.Then,checked the simulated value against the experimental values,and the CFD was considered valid.Finally,the CFD model was used to analyze the temperature and airflow distributions in the experimental greenhouse with and without tomato under the forced ventilation.Three-dimensional CFD model for a Venlo-type greenhouse under forced ventilation was established,using the CFD model.The turbulence transfer was described by the standard k-εturbulence model,and dealt with the near-wall region using the standard wall function.The tomato crop was described by means of the porous medium approach proposed by Darcy and modified by Forcheimer to establish the mathematical model between the crop cover and the air velocity.The model simulations were validated with respect to temperature and airflow fields measured inside the experimental greenhouse for fairly steady-state outside condition around the solar noon.The average relative error between the simulated and measured air temperature was 7.5%,with the biggest relative error of 15%.A good agreement was observed between the measured and simulated values for inside air temperature and velocity.It was next used for exploring the details of the inside air temperature and airflow fields.It revealed the details of the air temperature and airflow distributions within the greenhouse.The maximum temperature difference along north-south inside the greenhouse were 3.75℃and 7℃.The temperature of the roof and the wall was taller than the other inner space,and the temperature of crop was lower;the air temperature rise was very slow from east to west,also from north to south;air temperature.Temperature near the wet curtain was relatively flat,but there was a large range of temperature near the fans.The tomato crop could slow down the air flow.The velocity was 0.4m/s～0.8m/s within the crop in the greenhouse without tomato,and the velocity was 0.2m/s～0.35m/s in the greenhouse with tomato.The velocity near the east wall was lower than the velocity near the west wall.The exit of the fan speed to the outside was emitted spherically.Through the comparison and verification between the CFD simulated values and the experimental values,we can discovered that there was a high accuracy of the three-dimensional CFD model for a Venlo type greenhouse with and without tomato crop under forced ventilation.The CFD model can provide theoretical basis of structure and the forced ventilation system design in the Venlo greenhouse.