Energy performance enhancement of Trombe walls using 3D geometric ribs

Abstract

In this study, a numerical analysis was conducted to evaluate the impact of different triangular baffle geometries integrated into a Trombe wall on its thermal and hydrodynamic performance. Four configurations were tested: Model 1 (solid rectangular ribs), Model 2 (solid triangular ribs), Model 3 (crossed triangular ribs), and Model 4 (spaced triangular ribs). The simulations, carried out using the CFD method in ANSYS Fluent, covered a Reynolds number range from 600 to 1600 and focused on the analysis of several dimensionless quantities: The Nusselt number (Nu), the friction factor (f), the Poiseuille number (Po), the Colburn factor (j), and the overall thermal enhancement factor (η). The results show that Model 3 provides the most significant enhancement in heat transfer, with a Nusselt number of Nu = 24.26 at Re = 1600, representing a +95.5% improvement compared to the smooth channel (Nu 0 = 12.41). However, this model also leads to the highest pressure losses (f = 0.165, Po = 263.3), which could negatively impact overall energy efficiency. Model 4, on the other hand, offers a similar thermal performance (Nu = 23.65, i.e., +90.6%) while better limiting pressure drops (f = 0.153, Po = 244.3), resulting in the highest enhancement factor: η = 1.51. Model 2 also achieves a good compromise (Nu = 24.83, η = 1.32), whereas Model 1 shows the lowest thermal performance (Nu = 20.88, η = 1.31). Thus, the study highlights the importance of geometric design in optimizing Trombe walls. Models 3 and 4 emerge as the most promising configurations, depending on whether the focus is on maximizing heat transfer or balancing it with hydrodynamic constraints.