Enhancing the thermal performance of an agricultural solar greenhouse by geothermal energy using an earth-air heat exchanger system: A review

In recent years, yearly climatic changes, continuous temperature increases, and the impact of global environmental change have seriously affected agricultural production. The solar greenhouse (SG) system is designed to maintain suitable temperatures and humidity levels for cultivating plants. For this purpose, an earth-to-air heat exchanger (EAHE) can be coupled with the SG to provide the necessary heating and cooling required to maintain suitable conditions for vegetation. This review presents a comprehensive literature survey on SG-EAHE systems. The thermal characteristics of heating and cooling modes are presented for SG-EAHE systems. Reports indicate that integrating EAHE with the SG can meet the heating and cooling needs of the SG while significantly reducing water consumption. The design parameters of EAHE, such as configuration, pipe diameter, pipe length, and buried depth, can affect the performance of SG-EAHE systems. Additionally, integrating photovoltaic (PV) and photovoltaic/thermal (PVT) systems with SG-EAHE systems was discussed. Moreover, the challenges and prospective aspects of SG-EAHE systems were identified.