Applications of building-integrated coil-type ground-coupled heat exchangers - Comparison of performances of vertical and horizontal installations

The building-integrated coil-type ground-coupled heat exchanger (GCHE) was used to overcome the high installation cost of the heat exchanger. A field test and simulations were conducted to analyze the performance of GCHE when installed vertically or horizontally. The vertical GCHE refers to the coil-type GCHE installed at the center of a PHC (pre-stressed high-strength concrete) pile used for the building foundation. The horizontal GCHE refers to the coil-type GCHE laid horizontally on the bottom of the building. The amount of electric power consumed by the horizontal GCHE system was higher than that consumed by the vertical GCHE system. The coefficient of performance (COP) through a cooling experiment was identified as 3.9-4.3 for the vertical type and 3.3-3.7 for the horizontal type. The simulation model was used to examine the annual performance evaluation for the vertical and horizontal GCHEs. The comparison of the year-round energy consumption values showed that the vertical GCHE has about 15% higher heating/cooling efficiency than the horizontal GCHE. The return period was six years in both the horizontal and vertical GCHEs for the short term, but the cost saving in the vertical GCHE was about 28% higher in the long term.