Research progress on the enhancement of heat transfer performance of ground heat exchangers: A review

Abstract

Ground heat exchangers (GHEs) play a crucial role in enhancing the efficiency of ground source heat pump systems (GSHP), and there has been extensive research on geothermal energy utilization. This paper reviews prior studies focused on enhancing the heat transfer efficiency of GHEs. It provides a comprehensive summary of methods for performance improvement, including structural improvements of GHEs, selection of backfill materials, consideration of different geological conditions, choice of working fluids, pipe arrangement patterns, heat supplementation devices, and operational modes. The analysis indicates that future research should focus on finding more suitable backfill materials and working fluids, achieving multi-energy complementation between geothermal energy and various renewable energy sources or industrial waste heat. Additionally, attention should be given to the rational arrangement of ground heat exchanger pipe groups and passive heat transfer enhancement components. Furthermore, research methods should integrate numerical models with mathematical analyses to ensure efficient and accurate guidance for engineering applications.