• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5C
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• pp.177-183
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• 2012

The use of energy pile foundation has been increased for economic utilization of geothermal energy. In particular, a coil-shaped ground heat exchanger (GHE) is preferred than conventional U-shaped heat exchanger to ensure better efficiency of heat exchange rate. This paper presents experimental results by changing different pitch spaces of spiral coils. Joomunjin sand was filled in a steel box of which the size was $5m{\times}1m{\times}1m$. Thermal response tests (TRTs) were conducted to measure the ground thermal conductivity with temperatures of circulating water using line source model and ring coil model. Experimental results and analytical solutions were compared to validate the applicability of these models. Ring coil model showed more accurate similar results with experimental data rather than line source model and cylindrical source model.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.2
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• pp.69-74
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• 2015

In this work, we studied the shell and helically coiled tube heat exchangers. Shell and coil heat exchangers with different rate of water flow and plate heat exchanger with same capacity were tested for condensing conditions. We proposed design guide using modified Wilson plot method. We compared fouling characteristics between shell and coil heat exchanger and plate heat exchanger, when they were washed and were not washed. The shell and coil heat exchanger showed 120% of higher saturated fouling resistance value and 4% of better heat transfer ratio than the plate heat exchanger.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.37-51
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• 2013

An energy pile encases heat exchange pipes to exchange thermal energy with the surrounding ground formation by circulating working fluid through the pipes. An energy pile has many advantages in terms of economic feasibility and constructability over conventional Ground Heat Exchangers (GHEXs). In this paper, a coil-type PHC energy pile was constructed in a test bed and its thermal performance was experimentally and numerically evaluated to make a preliminary design. An in-situ thermal response test (TRT) was performed on the coil-type PHC energy pile and its results were compared with the solid cylinder source model presented by Man et al. (2010). In addition, a CFD numerical analysis using FLUNET was carried out to back-analyze the thermal conductivity of the ground formation from the Ttype PHC energy RT result. To study effects of a coil pitch of the coil-type heat exchange pipe, a thermal interference between the heat exchange pipes in PHC energy piles was parametrically studied by performing the CFD numerical analysis, then the effect of the coil pitch on thermal performance and efficiency of heat exchange were evaluated. Finally, an equivalent heat exchange efficiency factor for the coil-type PHC energy pile in comparison with a common multiple U-type PHC energy pile was obtained to facilitate a preliminary design method for the coil-type PHC energy pile by adopting the PILESIM2 program.