3374 -- Laboratory and Computer Comparisons of Ground-Coupled Heat Pump Backfills (same as AT-90-8-3) PDF

This research compared several backfill materials for use with horizontal ground-coupled heat pump (GCHP) systems using experimental and numerical models. To experimentally model the situation, a small scale GCHP simulator of full-scale GCHP performance was used in conjunction with three backfill materials and the native soil of the test. A finite element model was also created to solve the two coupled nonlinear partial differential equations governing heat and mass transfer in moist porous media. The computer model gave results that slightly underpredicted the temperature response of the buried ground coil and the media around it, but it gave proportionally correct results in ranking four backfills. Both the simulator and the model predicted better heat exchanger performance for the native soil and an acrylic latex/sand backfill and worse performance for paraffin/sand and moist sand backfills.

KEYWORDS: fill, heat pumps, soil heat pumps, testing, calculating, performance.