This study presents a numerical evaluation of a Horizontal Rectilinear Earth–air Heat Exchanger (EAHE), considering the climatic and soil conditions of Viamão, Brazil, a subtropical region. The Constructal Design method, combined with the Exhaustive Search, was utilized to define the system constraints, degree of freedom, and performance indicators. The degree of freedom was characterized by the aspect ratio between the vertical and horizontal lengths of the elliptical cross-section duct (H/L). The performance indicators for the EAHE configurations were assessed based on thermal potential (TP) and pressure drop (PD). The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was applied for multi-objective evaluation, and a methodology for EAHE is proposed. The problem was solved using FLUENT software (version 2024 R2), which employs the Finite Volume Method to solve the conservation equations for mass, momentum, and energy. The (H/L)_T,o = 6.0 configuration showed a 16.4% increase in thermal performance for heating and 15.9% for cooling compared to the conventional circular duct. Conversely, the (H/L)_F,o = 1.0 configuration reduced pressure loss by 65.33%. The integration of Constructal Design with TOPSIS facilitated the identification of optimized geometries that achieve a balance between performance indicators and those that specifically prioritize thermal or fluid dynamic aspects, being this approach an original scientific contribution of the present work.

This study evaluates the impact of integrating Phase Change Materials (PCMs) in the efficiency of Ground-Air Heat Exchangers (GAHEs). A three-dimensional computational model for the GAHE system with an integrated annular PCM (GAHE-PCM) was implemented in ANSYS Fluent using the Finite Volume Method, accounting for the meteorological conditions and ground properties of Viamão, Brazil. A parametric evaluation with fifteen rectangular and fifteen elliptical PCM container configurations were analyzed by varying their geometric ratios. Results indicate that the inclusion of PCM may enhance the yearly thermal potential as high as 69.31% in heating and 27.92% in cooling. Geometries, such as square or circular cross-sections, maximize heat exchange with the airflow, whereas elongated shapes reduce PCM efficiency. Furthermore, placing most of the PCM in deeper, thermally stable soil layers reduces the overall performance. For near-optimal designs, the differences between rectangular and elliptical containers are minimal, providing flexibility for system implementation.

Developing clean energy technologies to harness ocean waves remains a key engineering challenge. In this context, the influence of geometry on the performance of an oscillating water column (OWC) wave energy converter through the Constructal Design method is investigated. The objective is to maximize available hydropneumatic power when the system is subjected to full-scale regular waves. An inclined plate apparatus was inserted at the bottom of the OWC to evaluate its performance at inclinations of 0°, 20°, 40°, 60°, 80°, and 90° relative to the vertical direction. A validated and verified computational model based on the finite volume method was employed. The multiphase volume of fluid model was applied to handle air–water interaction. Results showed that the highest hydropneumatic power was achieved at 80°, which is 30.47% superior than the worst case with 0°.

O presente trabalho tem por objetivo avaliar numericamente um Trocador de Calor Solo-Ar Horizontal Helicoidal (TCSA-HH), considerando características climáticas e do solo do município de Viamão, RS, Brasil. A geometria do sistema é avaliada por meio da variação do passo entre as helicoides (Ph) do TCSA. O parâmetro utilizado para a análise do desempenho das diferentes configurações do TCSA-HH é através da avaliação do potencial térmico (PT) do sistema. O problema é solucionado numericamente utilizando o software FLUENT, que emprega o Método dos Volumes Finitos para resolver as equações de conservação de massa, quantidade de movimento e energia. Como resultado, os TCSAs-HH mostram-se apropriados para resfriamento do ar durante períodos quentes, embora a capacidade de aquecimento se apresente irrelevante em períodos frios. O TCSA-HH com Ph = 100 mm obteve o melhor desempenho relacionado ao PT, superando em aproximadamente 10% o TCSA-HH com Ph = 400 mm, que apresentou o pior desempenho térmico. Comparado a outros TCSAs presentes na literatura, o TCSA-HH apresentou um desempenho similar para condição de resfriamento, demonstrando ser uma alternativa viável para terrenos compactos.