Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Evaluating the performance of Earth-air heat exchangers coupled to a galvanized square cylinder under different installation depths
Submission Author:
Ana Maria Domingues , RS
Co-Authors:
Ana Maria Domingues, Jairo Ramalho, Honório Joaquim Fernando
Presenter: Eduardo Nóbrega
doi://10.26678/ABCM.ENCIT2022.CIT22-0361
Abstract
Earth-air heat exchangers (EAHEs) stand among sustainable alternatives for heating and cooling buildings. Such systems consist of one or more ducts buried at a certain depth and a ventilation system, which forces the air to flow inside the ducts, exchanging heat with the surrounding soil and entering the buildings at a milder temperature. Based on the literature, we decided to analyze EAHE composed of ducts coupled to galvanized structures with high thermal conductivity. In particular, this work considers the ducts enveloped by a rectangular prism (block) then we perform different numerical simulations to study the system performance when the installation depth varies. Here, we adopt climate and geotechnical data from the southern Brazilian city of Viamão. For the EAHE simulations, we employed a validated version of the so-called GAEA model, where the soil temperatures are estimated numerically in two dimensions, using the Finite Element Method. To evaluate EAHE performance, we determine the soil thermal potential (Ps), the EAHE thermal potential (Pt), and the EAHE efficiency (θ). Therefore, this article aims to evaluate how the depth of the block affects Ps, Pt, and θ. From the preliminary results, we have that coupling a duct to a galvanized block increases the system efficiency by about 30% compared to simulations without it. Placing the installation at 3.5 m, we estimated that Ps and Pt reach annual RMS values of approximately 4°C and 3.8°C, respectively.
Keywords
Earth-Air Heat Exchangers (EAHE), Thermal Potential, Renewable energy., GAEA model
