Design Construtal aplicado a trocadores de calor solo-ar utilizando modelagem numérica e analítica estacionárias e transientes

Abstract

Earth-air heat exchangers (EAHE) are an auxiliary resource to traditional air conditioning systems in improving thermal comfort conditions in built environments. Its low consumption of electrical energy and good thermal performance, in addition to the use of a renewable source of energy, the soil, emphasize the importance and urgency of its study. Several studies have addressed the application of EAHE in southern Brazil, due to its subtropical climate and favorable soil characteristics. In this work, three models are developed to evaluate the system’s employability in a locality, deduced from the equations of conservation of energy and mass. The solutions found for the models, both numerical and analytical, are verified and show high agreement with other data in the literature. In addition, a study is developed for the design of T-shaped EAHE based on the principles of Constructal Design. The results point to the system’s employability in the city of Porto Alegre, highlighting that the EAHE has a better heating potential than a cooling potential. For an installation depth of 3m, system performance improvement is observed for ducts up to 20m, but not for longer lengths. It is shown that the relative humidity of the air is fundamental in the evaluation of the performance of the system. In addition, numerical relationships for the dimensions of a T-shaped TCSA with 2, 3 and 4 levels are determined. This result can be used to design a system considering an installation area constraint.