Tufekchi V. Optimization of parameters of preparation and distribution of coolant for drying disk spraying complexes

The aim of the dissertation is to develop and improve the design of drying disk spraying complexes by theoretical and experimental study of the operating parameters of a given technological regulation formed on the basis of the results of CFD (computational fluid dynamics) flow modeling. The first chapter of the thesis discusses the classification of the main methods and processes of whey drying. Whey is an important by-product during dairy production, and its treatment and utilization are of great importance for production efficiency and loss avoidance. One of the main technical limitations and disadvantages that accompany spray dryers is the limited information available on the aerodynamic flows that occur inside the chamber of these systems. The limited technical data on aerodynamic flows complicates the process of optimizing the parameters of drying complexes, which can lead to suboptimal energy use, reduced productivity and product quality. Therefore, in order to ensure efficient operation, an urgent task is to improve the design and operational parameters of drying disk spraying complexes. The second chapter of the thesis presents a detailed methodology for conducting research on the hydrodynamics of dryers with centrifugal disk spraying. Hydrodynamics of dryers with centrifugal disk spraying - contains an analysis of the hydrodynamics of the internal chambers of drying plants, taking into account the specifics of centrifugal disk spraying. Turbulence models for the calculation of spraying complexes - contains a study of the turbulence model used to evaluate the spraying process in drying complexes. The methodology for studying temperature fields in the core of the spray chamber is based on the basic methods and tools used to measure temperature parameters in the core of the drying process. The third chapter of the thesis highlights the details of the research conducted to optimize the process of drying dairy products in a spray dryer. According to the results of the experiments, it was found that the optimal flow rate of the coolant along the inner surface of the walls of the spray dryer body is in the range of 20 to 25 meters per second. The study also revealed that temperature changes in the internal space of the drying complex have a significant impact on the movement of product and coolant particles. This emphasizes the importance of precise control of the pressure and temperature fields in the drying complex for optimal control over the drying process. The fourth chapter of the thesis is devoted to the proposed narrowing of the cross-section of the air guide device, which will increase the coolant velocity and improve the efficiency of drying dairy product particles. The narrowed part of the coolant supply device of a disk spray dryer has an additional positive effect on the coolant flow rate. Numerical modeling showed that the optimal coolant flow rate is 50 m/s. Another important result was the detection of pressure changes in different parts of the dryer. Based on the research, the relationship between the coolant flow rate and the angle of the flame spray was determined. It was found that the highest values of the flow rate are determined under the spray disk, where the flow rate reaches up to 40 m/s. It has been experimentally determined that at a louvered distribution control angle of 45 degrees, an increase in the flare spray angle is observed. In the fifth chapter of the dissertation, numerical studies were conducted using the CFD FLUENT package to analyze the spray drying process. The CFD FLUENT program was chosen to model the spray drying process, as it is a powerful tool for numerical analysis of mass and heat transfer processes in complex systems. To verify the accuracy of the numerical results, temperatures were measured at various points inside the spray dryer tower. Good agreement between the experimental and numerical data was achieved with a maximum relative error of 4.6%. It was found that during the initial experiments under "calm" conditions, when the coolant flow rate does not exceed 10 m/s and there is a convective air flow at the inlet, the k-omega CFD transient model (2 eqn) is effectively used. Analysis of temperature and humidity conditions: At a product feed rate of 120 m/s, the highest temperature values are observed near the wall in Group A at a height of 3200 mm from the tower. It was found that the studies related to changing the parameter of the input coolant supply to the drying complex at a temperature of 180°C and the predicted residual moisture content of the dried product at 0.41%. Conclusions and Prospects: The developed modeling method can be useful for the further development and improvement of industrial spray dryers, providing more accurate and efficient operation of these devices.