20 September 2011
The main building of Obayashi Corporation Technical Research Institute was built in Kiyose City, Tokyo in September, 2010. The ground source heat pump (GSHP) system was adopted for radiant heating-cooling and desiccant air-conditioning in workplace. Three kinds of unique ground heat exchangers (GHEs) are used as heat exchanger; vertical double U-tube GHE with highly conductive backfill material, vertical single U-tube GHE which has
been tied to H steels of the earth retaining wall, and horizontal GHE under the basement foundation. They were developed for the purpose of the cost reduction or improvement of the heat extraction/injection performance. This paper reports the thermal performance of the GSHP systems in winter season (Dec.2010~Feb.2011).
As a result, outlet brine temperatures of all GHE types were higher than outside air temperature. When we compared the ratios of heat extraction performance of GHEs, vertical GHE using double U-tube was the highest of three kinds of GHEs. The heat extraction rate of vertical GHE with highly thermal conductive backfill has increased compared with that of vertical GHE with normal backfill.