ANALYSIS OF THEORETICAL STUDIES OF DEVICES FOR DOSING AND MIXING NUTRIENT SOLUTIONS

Fertigation systems play an important role in greenhouse crop production, which allow combining irrigation and fertilization processes, providing optimal plant nutrition. The main task of such systems is accurate dosing and uniform mixing of nutrient solutions, including different types of fertilizers, with water. Fertigation technology makes it possible to significantly reduce the loss of water and fertilizers, as well as to increase the efficiency of their use at various stages of plant growth. However, the effectiveness of these systems depends on the quality of the mixing and dosing devices, which must ensure the uniform distribution of nutrients in the solution. Today, there are different designs of mixers for the preparation of nutrient solutions: mechanical mixers with moving elements and static mixers that use hydraulic flows for mixing. Mechanical mixers are suitable for solid and hard-to-dissolve fertilizers, but their operation is complicated by the presence of moving parts. Static mixers are easier to use and have no moving parts, making them efficient and reliable for fertigation systems. The analysis of theoretical studies of devices for dosing and mixing nutrient solutions, in particular, jet mixers that work according to the static principle, has been carried out. The considered devices for preparing liquid mixtures are of the ejector type, on the basis of which many modern systems are built. The main attention is paid to the calculations of the optimal geometrical parameters of jet dispensers-mixers. The theoretical studies of most scientists are focused on determining the injection coefficient — as a key parameter that determines the efficiency of mixing and dosing. Theoretical approaches also include models of turbulent particle transport and semi-empirical equations to evaluate mixing quality. However, the issue of practical assessment of the quality of multi-component mixer-dispenser mixtures remains insufficiently studied.