Experimental and CFD Results on the CO2 Distribution in a Semi Closed Greenhouse

This work aims at predicting CO2 concentration inside an experimental energy saving and semi closed greenhouse with a tomato crop. For that purpose, a 3D model of a cropped greenhouse has been created, including a discrete CO2 injection system and an air-cooling and dehumidifying system. The model has been developed using the Fluent CFD code. For simulating radiative exchanges, a Discrete Ordinates (DO) model was enabled, together with sensible, latent and radiative heat transfers related to crop activity and mass transfers (water vapor and CO2) were simulated within the crop rows considered as equivalent porous and semi-transparent media. This approach allows computing the distributed crop photosynthesis. Experimental measurements were performed for the determination of the spatial and dynamic distribution of climate parameters and CO2 distributions within the greenhouse and in its vicinity in order to be used as boundary conditions by the CFD model. Comparisons between the simulated and the measured values of the CO2 concentration inside the greenhouse are presented for a whole day time. The simulated net CO2 consumption is also determined and presented. Finally, we also analyzed the sensitivity of the distribution of CO2 in the greenhouse vs. the attenuation of solar radiation across the crop rows.