Effects of internal airflows on the heat exchange potential and mechanics of energy walls

Abstract

Energy walls are earth retaining structures equipped with pipe heat exchangers that harvest thermal energy sources from underground. Unlike fully embedded energy geostructures such as energy piles, energy walls interact not only with the ground but also with internal airflows under a wide range of conditions. Yet little is known as to how the internal airflows affect the heat exchange potential and mechanics of energy walls. In this paper, we conduct a systematic investigation into the effects of internal airflows on various aspects of energy wall performance, from the harvestable thermal power to the structural behavior. We construct and validate a numerical model of a full-scale energy wall. We then utilize the model to develop a comprehensive understanding of how internal airflows affect the energy, geotechnical, and structural performance of energy walls under a wide range of site and operational conditions. Results show that an internal airflow not only increases the heat exchange potential of energy walls but also leads to marked variations in the thermally induced axial forces, shear forces, and bending moments in the walls. Our findings consistently indicate that even minimal airflows should be considered in the analysis and design of energy walls.