ABSTRACT
This study evaluated the feasibility of steel-making slag-based controlled low-strength materials (CLSM) as a heat transfer medium for horizontal ground source heat pump systems. Engineering properties of CLSM mixtures with different steel-making slag contents and steel-making slag types were evaluated. The in-door thermal response test was conducted to validate the numerical model and access the heat exchange rate of spiral-coil GHE backfilled with CLSM and natural sand. Finally, to access the beneficial use of the CLSM over the sand, economic analysis of 50 case studies for the horizontal GHE was performed. The results indicate that the ground type steel-making slag-based CLSM not only can replace the sand in the CLSM mixture but also can enhance the thermal conductivity up to 2.35 W/(mK). Another advantage of CLSM is a high air-entry value, which can limit the influence of the GWT drop. As expected, the GHE backfilled with the CLSM shows a better economic performance compared to that of the GHE backfilled with an ordinary soil owing to its high heat transfer performance.
