Multi-criteria optimization of an earth-air heat exchanger for different French climates

The Earth-Air Heat Exchanger (EAHE) is a system for cooling or preheating the blown air into a building. A modeling of this system is proposed from a model for the ground and a model for the exchanger. The results are in agreement between the outside air temperature of the numerical model and the experimental temperature measurements. A sensitivity analysis with factorial plans is carried out to determine the most impactful parameters, taking into account two energy criteria and one economic criterion. The results show that tube radius, tube length, air velocity, burial depth and soil nature are the most impactful parameters. A multi-criteria optimization study with genetic algorithms is then performed to determine the Pareto front. The criteria do not evolve in the same trend because when the cost of the energy recovered decreases, the coefficient of performance and the EAHE efficiency will deteriorate, and reciprocally. Finally, a multiple-criteria decision-making is carried out using the TOPSIS method to provide the optimal pipe configuration. The optimal solution provides a large tube length, an intermediate burial depth, and a small air velocity and tube radius. The EAHE can achieve strong energy performance in any French climate. (C) 2020 Elsevier Ltd. All rights reserved.