ABSTRACT
Energy pile systems consist of three major components: the ground heat exchanger (absorber pipes), which is placed in the pile; the heat pump and the heating/cooling closed-pipelines network, which embedded in the floors and walls of the building. Hamada et al. (2007) conducted a series of tests on performance of three types of heat exchangers: U-shaped, double U-shaped and indirect double-pipe. Considering the result of tests as well as the viewpoint of workability and economic efficiency, U-shaped heat exchanger was employed. Absorber pipes are generally made of high-density polyethylene (HDPE), but PVC (Poly vinyl chloride) has also been used in the past (Gao et al. 2008). Heat carrier fluids, which are circulated through absorber pipes to exchange energy, are water with antifreeze solution like glycol to avoid freezing in cold regions. Under principles of design, the return temperature of the fluid in circulation should not fall below zero with a 2◦C safety margin (GSHPA, 2012).
