SCIENTIFIC SUBSTANTIATION OF THERMOHYDRODYNAMIC PROCESSES AND LIMITING VACUUMING PARAMETERS IN THE DESIGN OF ROTARY UNITS FOR RAPID COOLING OF BAKERY PRODUCTS USING CFD MODELING METHODS

Abstract

The article solves an important engineering and technical problem related to accelerating the cooling process of bakery products by designing and proving the feasibility of the parameters of a new rotary vacuum unit. The need to abandon traditional convection approaches, which take as long as 180–240 minutes and lead to a noticeable weight loss (3,5–5,0%), in favor of continuous vacuum technologies has been confirmed. Scientific methods have proven that the use of a rotary design with several sections contributes to the organization of flow production, which is vital for modern large-scale enterprises.

The research methodology is based on a comprehensive approach that integrates computational fluid dynamics (CFD) methods using the ANSYS Fluent software package and experimental testing on a pilot stand. A mathematical model of heat and mass transfer in the capillary-porous granular material of bread has been created, which takes into account the phase change of water and the dynamic pressure conditions at the boundary. Using numerical modeling, it was possible to establish maps of vapor velocity distribution and internal pressure gradients in the crumb. The limiting rate of vacuum creation (1,5–1,8 kPa/s) was determined, which stimulates intense evaporation of moisture without destroying the internal structure of the product.

The Cross-Vacuum system concept was introduced and substantiated for the first time – an improved algorithm for step-by-step pressure equalization between rotor chambers. The logic of controlling this process based on an industrial PLC controller is described in detail, providing flexibility in adjusting cooling conditions for a wide range of products. Test results showed a reduction in cooling time to 4–6 minutes, a 2,5% reduction in moisture loss compared to convection, and 22–28% energy savings due to the recuperation effect. The article will be of considerable practical value to design engineers and technologists in the baking industry, as the proposed equipment frees up to 80% of the production space normally occupied by traditional cooling devices (coolers).