Study of the features of modeling microwave vacuum evaporation

Abstract

Evaporation is the most common concentration method. The complete reuse of latent thermal energy by means of mechanical recompression is the most technologically efficient method of operation of evaporators. This method requires much less electricity to compress the secondary steam compared to the heat of the secondary steam. In this scheme, the energy released during steam condensation can be used to heat the initial solution, which makes it possible to achieve the reuse of thermal energy at the level of 95%. Thus, during the the evaporation process implementation, when energy is supplied by electromagnetic microwave radiation, conditions are created for the initiation of vaporization in the entire liquid volume, which will avoid product overheating in the thermal boundary layer due to the absence of such. This allows to get a product of high concentration, without the taste of “cooking”, without changing color and flavor. When modeling these processes, boundary conditions of the third kind are replaced by boundary conditions of the second kind. Considering the proposed hypothesis, a process model can be considered, assuming the presence of internal energy sources evenly distributed in the product volume. This opens up the possibility of using deterministic mathematical models, provided that the corresponding initial and boundary conditions are determined. As a result of generalization of the experimental modeling results, a model in a criterion form has been obtained, which allows calculating a microwave vacuum-evaporation apparatus of periodic action for solutions containing polar molecules. The model in the range of dimensionless pressure 2 ≤ P ≤ 22, and at the level of dimensionless heat of the phase transition 1 ≤ R ≤ 4.56 provides accuracy with a maximum deviation of ± 8%.