Ground source heat pumps are one of the key technologies for low-carbon heating and cooling. Continuous heat extraction or rejection may lead to ground thermal imbalance, which affects system performance. Improving heat exchange while stabilizing ground temperatures remains a significant challenge for the widespread deployment of this type of heat pumps.
Current practice focuses on improving borehole heat exchanger design and increasing grout thermal conductivity to enhance heat transfer. Highly conductive grouts accelerate ground temperature fluctuations, which could worsen long-term thermal balance.
The study investigates a coaxial ground heat exchanger using four different grouting materials, including micro-encapsulated and shape-stabilized phase change material. A validated numerical model was employed to simulate alternating heating and cooling cycles and to analyze heat transfer, specific power, and ground temperature variations.
We demonstrate that integrating phase change materials into the grout can simultaneously improve heat transfer and stabilize soil temperature.
Future research will focus on experimental validation, durability studies under repeated thermal cycling, and economic feasibility to support real-world adoption of PCM-enhanced geothermal grouts.
The work is a consequence of scientific cooperation between the Faculty of Mechanical Engineering, University of Ljubljana and the Department of Engineering, University of Napoli “Parthenope”. We are launching a joint master’s program in power and process engineering with this Italian university in the upcoming academic year, and we also have an agreement signed for double doctoral degrees.
Link to the article: here
Authors: Dr. Fawad Ahmed, Prof. Dr. Nicola Massarotti, Prof. Dr. Božidar Šarler
