A new control strategy to improve the ground source heat pump's efficiency with a recycled product

Despite numerous efforts to impose control measures on the heat pump side of Ground Source Heat Pump (GSHP) systems, there has been little thought into the potential of control on the ground characteristics. This is perhaps because of a predisposition to believe that ground related works usually are associated with extra capital investment that makes any modification less favorable than making changes to the heat pump unit. An effective control strategy with a non-homogeneous soil profile for the ground side of horizontal GSHPs was investigated in this research. The model incorporates the effects of a variety of surface energy fluxes to provide an accurate estimate of the ground thermal regime. The developed model was utilized successfully in conjunction with the MATLAB Genetic Algorithm (GA) toolbox to obtain the optimized operational parameters for a GSHP in a cold climate condition (Buffalo, NY). A properly sized and engineered non-homogeneous soil profile demonstrated the potential to boost the capacity of GSHP systems to a significant level. The potential benefits of a recycled product of tire industry, Tire Derived Aggregate (TDA), as an insulation blanket was assessed via the optimization algorithm. TDA was demonstrated to be effective in heating mode in a cold climate environment by increasing the energy extraction rates from the ground by about 15% annual. The annual percentage increase in energy dissipation rate to the ground, in cooling season, with TDA blanket was 7.6%. The results are suggestive of the beneficial application of a layered system to increase the performance of GSHPs. A shift in design perspective toward consideration of more control strategies for the ground pipe side of GSHPs is suggested based on the model results.