Comparative 4E analysis (energetic, exergetic, environmental and economic) between geothermal heat exchangers and cooling towers in large air conditioning systems in tropical climates

Abstract

The operation of air conditioning systems in tropical climates requires a significant input of electrical energy. Moreover, the expansion of the global economy and the phenomenon of climate change have led to a surge in demand for refrigeration and air conditioning. Geothermally assisted air conditioning systems are recognized globally as an effective solution for enhancing performance. Given the aforementioned advantages, this technology is currently employed on a large scale in several countries. Nevertheless, it remains relatively uncommon in tropical climates and there is a paucity of studies that compare large water chiller and ground source heat pumps for this type of location. The objective of this study is to evaluate and compare the energetic, exergetic, environmental, and economic performance for these two configurations. The experimental data are employed to validate the mathematical model that carried out simulations for four Brazilian cities using environmental conditions of 2023. The results indicated that the annual reduction in electricity consumption varies between 2.1% and 9.5%, in line with the emissions of pollutants. Additionally, the TEWI of the geothermal system is reduced between 1.7% and 7.5%. If the boreholes are constructed concurrently with the construction of the building, the payback period varies between 3.4 and 6.1 years. This indicates that constructing the boreholes at the same time as the building reduces costs, as well as saving energy and reducing the environmental impact of the large air conditioning system in tropical climates.