Gryshchenko R. Dynamics of ice melting in the elements of energy accumulators, system cooling and air conditioning

In the dissertation work the results of complex theoretical and experimental re-search of processes of heat exchange and hydrodynamics in water during ice melting at the mixed mode of convection with prevailing effects of buoyancy are resulted. Sci-entifically substantiated and developed methods for calculating heat transfer processes in order to obtain semi-empirical dependences for calculating the intensity of heat transfer in water during ice melting. It is proposed to use the Le Shatelye-Brown principle to develop a general form of the calculated correlation dependence in the form of a superposition of the mechanisms of natural and forced convection. Calculated dependences for determination of heat exchange intensity during mixed turbulent and transient convection in a closed cavity are developed, which ade-quately describe the results of experimental research. The proposed CFD-modeling technique, which allowed to verify the "Standard k-ε", "Standard k-ω" and "SST k-ω" turbulence models based on the ANSYS CFX code for numerical simulation of transfer processes according to the conditions of mixed water convection near the inversion point. Correction of the turbulent analogue of the Prandtl number without changing the standard model coefficients in the "SST k-ω" model of turbulence allows to obtain an adequate numerical model of heat transfer during mixed convection in water with the predominant effect of buoyancy. Analysis of the simulation results showed that the application of the developed model of turbulent analogue of Prandtl number in "SST k-ω" model of thermohydro-dynamic calculated CFD-package based on ANSYS CFX code allowed to obtain satis-factory correspondence of heat exchange calculation results to experimental data. in-version points in a confined space. Namely, during mixed quasi-stationary convec-tion, regardless of the value of Tm * (density inversion parameter), three circulation circuits are observed, the relative size of which is determined by the ratio of forced and free convective components. One circulation circuit is generated by a reversible boundary layer of natural convection near the cooling surface. The other two circula-tion circuits are generated by a flooded fluid jet around the surface of its symmetry. It should be noted that the symmetry surface of the flooded liquid jet is obvious-ly characterized by a maximum velocity. And since, the values of the liquid velocity extremes correspond to the zero values of shear stresses and, obviously, they are characterized by the minimum values of the value of turbulent kinetic energy. Analysis of TKE profiles can be concluded that its production is determined, first of all, as ex-pected, by the forced convective component of motion. The maximum values of TKE are observed in the area of the flooded liquid jet. Near hard surfaces outside the jet, the value of TKE goes to zero. That is, the processes of transfer under the action of buoyancy forces are realized mainly due to the viscosity mechanism. This means that, as expected, the modes of fluid motion due to the buoyancy forces near solid surfaces are not turbulent, but transitional from laminar to turbulent (transient flow). Also in the work the function of optimization of the managed CTES based on the principle of summation of expenses is developed. An algorithm for taking into ac-count partial load and environmental parameters on the efficiency of CTES equipment has been developed.