Canary Greenhouse CFD Nocturnal Climate Simulation

Hassan Majdoubi,Allal Senhaji,Salma Elbahi,Lahcen Bouirden,Thierry Boulard,Hicham Fatnassi,Mhamed Mouqallid,Hassan Demrati

doi:10.4236/ojfd.2016.62008

Abstract

The aim of this paper is to predict in details the distributed nocturnal climate inside a one hectare Moroccan canary type tomato-greenhouse equipped with continuous roof and sidewalls ventilation openings with fine insect screens, by means of 3D CFD (Computational Fluid Dynamics) simulations by using a commercial Software package CFD2000 based on the finite volumes method to solve the mass, momentum and energy conservation equations. The turbulent transfers were described by a k-e model. Likewise, the dynamic influences of insect screens and tomato crop on airflow movement were modeled by means of the concept of porous medium with the Boussinesq assumption. Atmospheric radiations contribution was included in the model by customising the plastic roof cover temperature deducted from its energy balance. Also, the CFD code was customized in order to simulate in each element of the crop cover the sensible and latent heat exchanges between the greenhouse air and tomato crop. Simulations were carried out with a wind prevailing direction perpendicular to the roof openings (west-east direction). Simulations were later validated with respect to temperature and specific humidity field measurements inside the experimental greenhouse. Also, the model was verified respect to global sensible and latent heat transfers. Results show that, generally, greenhouse nocturnal climate distribution is homogeneous along the studies greenhouse area. The insect proof significantly reduced inside airflow wind speed. But there is no significant effect on the inside air temperature and specific humidity respect to outside.

Highlights

The use of canary plastic greenhouses type has been spreading along the Atlantic coast of Morocco, especially in souss valley [1]
In order to reduce the need for pesticide application, the greenhouse roofs and sidewall ventilation openings were equipped with fine insect screens which act as mechanical barriers to insect entry inside the greenhouse
The dynamic influences of insect screens and tomato crop on airflow movement were modeled by means of the concept of porous medium with the Boussinesq assumption

Summary

Introduction

The use of canary plastic greenhouses type has been spreading along the Atlantic coast of Morocco, especially in souss valley [1]. In the climate conditions prevailing in this region, efficient climate control is the major challenge that growers have to face. The resulting microclimate in this region is far from satisfactory for the crop during a large part of the year. In order to reduce the need for pesticide application, the greenhouse roofs and sidewall ventilation openings were equipped with fine insect screens which act as mechanical barriers to insect entry inside the greenhouse. The use of insect screens reduces the greenhouse air renewal and tends to increase the inside air temperature and humidity, and nearly precludes production. The performance and control of air exchange rate are crucial factors for crop growth during the hot and cold periods of year and for improved production yield and quality

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Conclusion