Tuz V. Heat transfer and hydrodynamics of steam-gas-liquid flows in channels with a mesh cover

A thesis submitted to the Department of Technical thermophysics and industrial heat-power engineering in conformity (05.14.06) with the requirements for the degree Doctor of Technical Sciences. The purpose of this work is to scientifically ground and develop the methods of the calculation of processes in contact apparatus with net coverage of walls of channels on the basis of complex theoretical and experimental researches of the processes of hydrodynamics and heat-mass exchange in the ring two-phase systems at the counterflow and phase transitions. Hydrodynamics of gravity film flow in the vertical channels with net coverage of walls was researched in the work. Nonlinear character of the film thickness changes at the mode of laminar flow liquid that is caused by capillary effects in the checker opening of net found out. There also were defined the limits of the hydrodynamic crisis phenomena, related to the kicking of film circulation affected by the influence of gas flow in channels with net coverage, that considerably allowed to extend the overhead range of work of contact apparatus. The system of equalizations by which the process of breaking of the film is described at a flow in the vertical channels with net coverage is analytically decided, and the lower limit of working range is experimentally determined. The processes of heat and mass exchange related to the phase transitions at the evaporation cooling of the non-isothermal film at the case of the forced motion and the natural convection of gas, in the cooling gas by the isothermal film and adiabatic boiling up of the overheated liquid in the channels of the nozzle of contact apparatus were complex analyzed. The influence of the regime parameters of contacting phases and geometrical characteristics of the apparatus' elements were determined in this work and empiric dependences for the calculation of intensity of heat and mass exchange in the initial areas and areas of stabilized heat exchange depending on the mode of flow of gas were also received. Keywords: hydrodynamics, heat-mass exchange, two-phase systems, film apparatus, passive intensifiers.