MODELING OF HYDRODYNAMICS AND HEAT TRANSFER IN A SPIRAL-CAPSULE THERMAL ENERGY STORAGE UNIT FOR THERMAL PREPARATION OF AUTOMOTIVE INTERNAL COMBUSTION ENGINES USING CAE SYSTEMS

Abstract

The paper presents the results of numerical modeling of hydrodynamic and heat transfer processes occurring in a spiral-capsule thermal energy storage unit designed for the thermal preparation of automotive internal combustion engines. The aim of the study is to analyze the coolant flow behavior in the spiral channels of the thermal accumulator, determine the spatial non-uniformity of the temperature field, evaluate the duration of the phase change process, and assess the efficiency of heat transfer from the heat-accumulating material to the working fluid. The numerical simulations were performed using computational fluid dynamics (CAE/CFD) methods based on the finite volume approach. Turbulent flow regimes of the coolant were described using the k–ε turbulence model, which provides a reasonable balance between computational accuracy and computational cost. The model accounts for the complex geometry of the spiral-capsule structure, heat exchange conditions between the coolant, the accumulator корпус, and the heat-storage medium, the phase change process within the heat-accumulating material, as well as the boundary conditions corresponding to the heat-release operating mode. The simulation results allowed determination of the phase change duration, thermal load, and identification of zones with non-uniform distributions of velocity and temperature. It was found that temperature differences between individual capsule elements may reach 15–25 °C, which significantly affects the efficiency of utilization of the stored thermal energy. The conducted study confirms the feasibility of applying CAE/CFD modeling as an effective tool for the analysis and optimization of thermal energy storage devices of various designs. The obtained results can be used to improve channel geometry, enhance the uniformity of heat release, and reduce the time required for thermal preparation of internal combustion engines, as well as to support further development of integrated models of thermal energy storage and utilization systems in vehicles.