Unsteady Heat and Mass Transfer in Structured Media and Gel

Modern trends in the development of chemical technology require a detailed study of the processes of heat and mass transfer in microchannels of various dispersed and microstructured media. This is due to the search for scientifically based ways to improve chemical and biochemical reactors, the need to create new equipment for nuclear energy and the current level of development of regenerative medicine towards the application of additive bioprinting technologies. In this case heat and mass transfer occur under non-stationary conditions, microchannels have a complex geometric shape, transfer can be accompanied by spontaneous convection, possible phase transitions, and chemical and biochemical transformations occur. Mathematical modeling of the outflow of a two-phase liquid-vapor medium from a layer of granular particles was performed using the method of smoothed particles hydrodynamics. The data on the visualization of the flow in the granular bed are presented. The dependences of the mass flow rate of the vapor-liquid mixture depending on the pressure drop in the pipe with a granular bed were established. The study of the occurrence and development of convective flows in the process of unsteady conductive heating of the cell wall with spherical and cylindrical particles has been carried out. Holographic interferometry with immersion optical tomography elements was used to measure temperature fields. Under the conditions of varying the thermophysical properties of the liquid, particles of the granular bed, as well as the magnitude of the supplied heat flux, the mechanism of the influence of filling on the time and nature of microconvection formation near contact spots was studied. A model of mass transfer in a gel was proposed for modeling the process of microorganisms feeding in the bioreactor. The model allows to determine the dynamics of microorganisms growth in the volume of the gel. In the experiments, gels based on agarose and a mixture of agarose and starch were studied. The proposed approach is promising for creating living tissue by bioprinting using gels.