Horizontal ground source heat pump modeling and performance enhancement via employment of tire derived aggregate to form a non-homogenous soil profile

Ground source heat pumps (GSHPs) take advantage of the stored energy in the ground for space heating and cooling. Their greater energy performance compared to conventional heating, ventilation and air conditioning (HVAC) is well documented. The key factors that hinder the wide adoption of these systems in the U.S. are relatively high installation costs, lack of knowledgeable installers and owners' uncertainty about their performance. The breadth of GSHP knowledge in the literature has a growing trend that requires new perspectives and performance evaluations to assist further penetration into the HVAC market. The current research investigates the potential application of a post-consumer product of tire industry, tire derived aggregate (TDA), in conjunction with horizontal GSHPs. TDA is composed of chipped scrap tires, which has relatively lower thermal conductivity and higher hydraulic conductivity than soil. TDA's properties could be advantageous in contrast with the properties of the soil overlaying the ground pipes; therefore, it was used as an intermediate layer to form a non-homogeneous vertical soil profile overlaying the ground pipes of a horizontal GSHP. In this research, numerical modeling was employed to study the impacts of the TDA layer on heat transfer regime to/from the ground pipes. A pilot scale set-up also was constructed in Buffalo, NY to explore the heating season performance in the presence of the intermediate TDA layer with actual data. At the end, the economic feasibility of utilizing TDA material with GSHPs was studied via numerical modeling of the whole building energy consumption in different climatic conditions. The outcomes of this research shed light on the design of the proposed non-homogeneous soil profile for horizontal GSHPs, which opens new frontiers in the energy and economic feasibility analysis of GSHP systems.