Borysenko A. Mathematical and computer modeling of heat exchange in the nanofluid heat transfer fluid of solar thermodynamic plants

The purpose of the study is development and generalization of models of mathematics and computer modeling of heat and mass transfer processes in the receiver system of solar thermodynamic plants; searching for methods of heat efficiency increase of receiver systems; proving the prospects of using nanofluid as the heat transfer fluid for intensification of convective heat transfer in heat receiver of solar thermodynamic plants; determination of relation between thermophysical and hydrodynamic parameters of nanofluid heat transfer fluid, which ensure maximum thermal efficiency at minimum hydraulic losses. The 3D non-linear mathematical model for determination of heat transfer features in receiver system of solar parabolic trough plant with nanofluid heat transfer fluid was developed in the first time. This model based on using the classical system of Navier-Stokes equations. The numerical algorithm and correspondent the customer software was also created. The addition of aluminum oxide to base heat transfer fluid (thermal oil) of solar parabolic trough plant leads to intensification of heat transfer in receiver system that increase of general efficiency system. This is was discovered in the first time using results of conducted numerical experiments. Significant grow of pressure losses in heat receiver with nanofluid in comparison with pure thermal oil was fixed. This is discovered in the first time using the obtained qualitative and quantitative parameters. The relation between Reynolds numbers and Nusselt numbers was found. This relation probes the necessity of thermodynamic optimization of the system. The entropy analysis based on principles of non-equilibrium thermodynamics was carried out in the first time. The optimal values of Reynolds numbers which ensure maximum thermal efficiency at minimal hydraulic losses were determined. The numerical algorithm which based on finite volume method was developed. The corresponding customer software was created. This software has generalized nature and with some correction can be used for analysis of flow in circular channel with nanofluid of any technological equipment. Moreover, the created software has flexible structure that allows without significant changes to transform its in depend on chosen nanofluid type and function system conditions. The results of presented study can be used during design and operation of modern solar energy plants of different temperature level and purpose with different types of nanofluid heat transfer fluids. The theoretical and practical provisions have become an integral part of educational subjects “Models and methods of applied mathematics”, “Methods of identification of parameters of mathematical models”, which are taught to students of higher education at the PhD level, specialty 113 – Applied Mathematics in Oles Honchar Dnipro National University. Conducted researches and their results make up the corresponding section of initial scientific work “Determinate and stochastic algorithms for computer modeling of objects and processes of different nature” (2022 – 2024, research supervisor Prof. Knysh L.I.) (state registration number: 0122U001467), which is carried out on Department of Computer Technologies, Faculty of Applied Mathematics, DNU.