Análise experimental de um sistema passivo de climatização utilizando o solo como trocador de calor

Abstract

Buildings account for a significant portion of energy consumption in Brazil, representing 52% of the total. A large portion of this consumption is attributed to HVAC systems used for both heating and cooling purposes. A promising approach to mitigate this energy demand is the adoption of passive cooling, with earth air heat exchangers standing out in this context. Due to the high thermal inertia of the ground, it can be utilized as a reservoir capable of heating or cooling the air, depending on the climatic conditions. These heat exchangers feature a simple and cost-effective design, primarily consisting of polyvinyl chloride pipes and a fan. The air circulating through the pipes of the heat exchanger is directed into the environment, thereby impacting its temperature and the thermal comfort of the occupants.The main objective of this experimental study is to construct and thermally analyze an earth air heat exchanger. The system was implemented to condition the air in a specific environment located in Block J1, at the Ponta Grossa campus of UTFPR. Multiple type K thermocouples were installed along the piping and in the ground to enable analysis of the thermal exchanges taking place. Additionally, comparisons were made with a non-conditioned environment located in the same block with similar dimensions. The obtained results demonstrated a good performance of the heat exchanger, as it enabled the reduction of the air temperature down to the ground temperature at a depth of 1.5 meters along approximately 45 meters of piping. When comparing the temperatures of the two environments, it was observed that the earth air heat exchanger provided milder temperatures and reduced thermal variation in the conditioned environment. However, in terms of the coefficient of performance (COP), it was found that the earth air heat exchanger did not reach high values compared to other studies in the literature. This can be primarily attributed to the high energy consumption resulting from the power of the fan used in the experiment (a 2 hp radial fan). Therefore, it is concluded that the heat exchanger can be a viable alternative for improving thermal comfort, especially in higher external temperatures.