Ground heat pump systems (GHPSs) are esteemed for their high efficiency within renewable energy technologies, providing effective solutions for heating and cooling requirements. These GHPSs operate by utilizing the relatively constant temperature of the Earth’s subsurface as a thermal source or sink. This feature allows them to perform greater energy transfer than traditional heating and cooling systems (i.e., heating, ventilation, and air conditioning (HVAC)). The GHPSs represent a sustainable and cost-effective temperature-regulating solution in diverse applications. The ground heat exchanger (GHE) technology is well known, with extensive research and development conducted in recent decades significantly advancing its applications. Improving GHE performance factors is vital for enhancing heat transfer efficiency and overall GHPS performance. Therefore, this paper provides a comprehensive review of research on various factors affecting GHE performance, such as soil thermal properties, backfill material properties, borehole depth, spacing, U-tube pipe properties, and heat carrier fluid type and velocity. It also discusses their impact on heat transfer efficiency and proposes optimal solutions for improving GHE performance.

This paper provides a comprehensive analysis of geothermal heat pump systems (GHPS), focusing on their advantages, disadvantages, key components, types, and ground heat exchangers (GHEs). It presents a detailed review of closed-loop GHE configurations, emphasizing their impact on heat transfer performance and installation costs. The findings show that helical GHEs offer superior thermal performance with reduced drilling depths and costs, while coaxial GHEs, particularly with steel tubes, enhance heat transfer efficiency and reduce borehole depth. Cost-effective solutions, such as W-type GHEs, deliver comparable thermal performance to more expensive configurations. Triple U-tube and spiral GHEs demonstrate high efficiency, balancing performance with economic considerations. The most commonly used borehole geometries are single or double U-tube configurations, while coaxial designs provide additional benefits in specific applications. These insights guide the optimization of vertical ground heat exchangers, improving performance, cost-effectiveness, and long-term sustainability in GHPS installations.