CFD analysis for evaluating and optimizing spatial distribution of CO₂ concentration in a strawberry greenhouse under different CO₂ enrichment methods

A deeper understanding of the spatial distribution of CO₂ concentration inside cultivation facilities (e.g., greenhouses and plant factories) is necessary for the quantitative evaluation and/or the improvement in the performance and efficiency of artificial CO₂ enrichment methods. We developed 3D computational fluid dynamics (CFD) models for two CO₂ enrichment methods in a strawberry greenhouse – one was for overall greenhouse enrichment, as the usual method, and the other was for localized crop enrichment. We confirmed the model validation by comparing the simulated and measured CO₂ concentrations in the greenhouse. With regard to the entire enrichment condition, CO₂ accumulated at the upper part of the greenhouse through convection due to the high temperature of CO₂ generated while there was low CO₂ concentration around the crops. This could be regarded as an ineffectual situation. However, such situation can be alleviated by lowering the temperature of CO₂. On the other hand, we found that crop-local enrichment can increase CO₂ concentration only around crops albeit with less effect on those at the upper part. Thus, changing the enrichment strategy as well as the equipment could greatly optimize the distribution of CO₂ in a greenhouse, thereby improving the efficiency of CO₂ enrichment.