Effect of geo-climatic conditions and pipe material on heating performance of earth-air heat exchangers

Climatological and geological site classification intended for Earth-Air Heat Exchanger Technology (EAHE) is an important factor in the design, implementation and optimal operation of such system. In this context, this paper presents an investigation on the heating performance and operating feasibility of two EAHEs in three different geo-climatic regions in Algeria. First, the performances of the EAHEs were experimentally studied in the temperate Oran climate and the corresponding results were used for validation of the numerical part. The experiment allowed to analyze the effect of the pipe material on the performance of the two EAHEs that are made of different materials (PVC and Zinc). After validation of the numerical part, the study was extended to three different climates including a temperate climate for Oran, an arid climate for Bechar and a steppe climate for El-Bayadh cities. For these climates, the heating study is rarely considered in this context. Furthermore, a sensitivity analysis was conducted in order to evaluate the operating feasibility of the EAHEs in the considered regions. The results revealed that the Zinc EAHE is more efficient in a temperate climate with a COP of 9.5 than in an arid or steppe climate with a COP of 8.2 or 8.1, respectively. However, the PVC EAHE is much better in an arid climate with a COP of 9.4 than in a temperate or steppe climate with a COP of 7.6 or 8.4, respectively. Otherwise, both EAHEs exhibited similar behavior in a steppe climate. The results show that the thermal performance of EAHE mainly depends on geo-climatic conditions and the type of pipe material. (C) 2020 Elsevier Ltd. All rights reserved.