Energy diaphragm wall thermal design: The effects of pipe configuration and spacing

Evaluation of diaphragm wall heat exchanger potential

“…Publications exploring potential of increasing heat exchange by increasing pipe diameter have not been found, while most studies have nominated 25 mm outside diameter pipe [3,12,14,35,37,[41][42][43][44][45]. The present authors suppose larger tubing would require greater investment in concrete to ensure covering and such would increase pipe-spacing, dictated by the practicalities of creating 180° bends return bends [41] could diminish performance. Fitting multiple vertical W loops of heat exchange tubing are more effective than multiple horizontal switchbacks with a return riser on the end [41].…”

“…The present authors suppose larger tubing would require greater investment in concrete to ensure covering and such would increase pipe-spacing, dictated by the practicalities of creating 180° bends return bends [41] could diminish performance. Fitting multiple vertical W loops of heat exchange tubing are more effective than multiple horizontal switchbacks with a return riser on the end [41]. Vertical U-and W-tubes cast into a diaphragm retaining wall modules of the Shanghai Museum of Natural History were initially rejecting over 120 W/mᵥ but soon dropped below 80 W/mᵥ and decayed to 50 W/mᵥ after 2-days continuous operation [3].…”

“…There has been a mixture of monitoring and modelling studies of DWHE performance (Table 1). In-situ thermal response testing have been limited a few hours, with a couple of exceptions [38,46], and so simulations are necessary to resolve inter-seasonal and inter-annual balances [41].…”

“…The contributions and limitations of the present work are incremental in the context of others [12,15,38,41,46], as each study has assumed a unique DWHE geometry. Uniquely the present work has integrated our DEFAULT DWHE with hourly simulations of building services of a prototypical multistorey office building floor plan so that one can estimate how many replicated stories could be sustainably served by geoexchange year after year without ever freezing in winter.…”

Performance characterization of novel caisson-based thermal storage for ground source heat pumps

“…The outer pipe assembly comprises a rebar cage on which 13 pipes filled with phase change material are attached. The rebar/reinforcement cage is made of steel and exists in typical foundation caisson for maintaining the structural integrity [22]. The inner pipe assembly (highlighted in green in Figure 3) consists of a ring onto which four U-loop pipes that are equally spaced are attached.…”