Simulações computacionais de convecção térmica em ambientes refrigerados utilizando o software OpenFOAM

Abstract

This dissertation presents a numerical study applied to the analysis and optimization of refrigeration and air-conditioning systems through Computational Fluid Dynamics (CFD), using the OpenFOAM software. The work is grounded on the formulation and solution of the governing conservation equations of mass, linear momentum, and energy, discretized by the Finite Volume Method (FVM). Incompressible flows with heat transfer by forced and mixed convection were considered, including turbulence modeling through the RNG k-ε and k-ω SST models. The methodology involved the validation of the numerical models using two classical benchmark test cases reported in the literature: forced laminar convection in a ventilated cavity and turbulent mixed convection in a bottom-heated cavity. Velocity, pressure, and temperature fields were analyzed, as well as relevant dimensionless parameters such as Reynolds, Prandtl, and Nusselt numbers. Comparison with experimental data and previously published numerical results demonstrated good agreement, confirming the reliability of the adopted models. Subsequently, the study was extended to the transient regime in order to evaluate the temporal evolution of the thermal field and identify stabilization criteria for steady-state conditions. The influence of supply air conditions, particularly inlet temperature and velocity, was investigated to determine critical parameters affecting the thermal and energy efficiency of the system. The results indicate that CFD-based computational modeling constitutes a robust tool for the integrated analysis of fluid dynamic and thermal phenomena in confined environments, enabling the identification of recirculation zones, high thermal gradients, and mixing patterns that directly impact energy performance. It is concluded that OpenFOAM provides adequate capability for HVAC-R applications, offering technical support for design optimization and contributing to the reduction of energy consumption and environmental impacts associated with indoor climate control.