Laboratory simulation of direct expansion ground coil heat exchangers.

摘要

Direction expansion ground coil (DXGC) ground coupled heat pump (GCHP) systems have certain energy efficiency advantages over conventional GCHPs. Principal among those are the elimination of the secondary heat transfer fluid heat exchanger and circulating pump. While the DXGC concept can have higher efficiencies, it also has more system design and environmental problems (e.g., compressor starting and oil return problems). General design guidelines for DXGC systems are not well documented. This study was aimed to experimentally look into some of the advantages and disadvantages of DXGC designs. A laboratory study of a DXGC heat pump system was performed. The results of the laboratory tests indicated that a DXGC can absorb from, or dissipate to, the ground, at least twice as much heat as conventional plastic tube ground coil heat exchangers. Some of the above mentioned concerns were also studied during the tests. A set of general design guidelines was derived from the test results and observations and is presented in this report. 9 refs., 11 figs., 1 tab.