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A platform for research: civil engineering, architecture and urbanism
Thermal performance and economic evaluation of double U-tube borehole heat exchanger with three different borehole diameters
Highlights We investigate thermal load of borehole heat exchangers with three borehole diameters. Increasing borehole diameter will slightly improve thermal performance of BHE. Increasing borehole diameter will decrease the economic profitability. Acceptable investments for a BHE with a larger diameter depend heavily on drilling cost.
Abstract This paper presents the results from experimental study of borehole heat exchangers (BHE) installed in a ground source heat pump (GSHP) system in Nuremberg, Germany. The BHE was constructed with 18 boreholes that can be grouped into three blocks: block I of 121mm, block II of 165mm and block III of 180mm. The operation of the GSHP system had been monitored between March 2009 and October 2012 for analysis. Over years of the system operation, the thermal performance of BHEs is observed to be slightly improved for larger borehole diameters (block II and III). For the comparison among the three blocks, thermal loads of block II is 1.64% and block III is 3.45% larger than that of block I, respectively. Furthermore, saving-to-investment ratio (SIR) is evaluated for two parts: the basic part (SIRI) for block I; the extra parts (SIRII-I, SIRIII-I) for block II and block III. Over a thirty-year period the SIR is estimated to be 4.80, 2.14 and 3.18 for SIRI, SIRII-I and SIRIII-I, respectively. These findings suggest that block I has the highest economic profitability. Based on these evaluations, the acceptable drilling costs for block II and block III are also analyzed and discussed.
Thermal performance and economic evaluation of double U-tube borehole heat exchanger with three different borehole diameters
Highlights We investigate thermal load of borehole heat exchangers with three borehole diameters. Increasing borehole diameter will slightly improve thermal performance of BHE. Increasing borehole diameter will decrease the economic profitability. Acceptable investments for a BHE with a larger diameter depend heavily on drilling cost.
Abstract This paper presents the results from experimental study of borehole heat exchangers (BHE) installed in a ground source heat pump (GSHP) system in Nuremberg, Germany. The BHE was constructed with 18 boreholes that can be grouped into three blocks: block I of 121mm, block II of 165mm and block III of 180mm. The operation of the GSHP system had been monitored between March 2009 and October 2012 for analysis. Over years of the system operation, the thermal performance of BHEs is observed to be slightly improved for larger borehole diameters (block II and III). For the comparison among the three blocks, thermal loads of block II is 1.64% and block III is 3.45% larger than that of block I, respectively. Furthermore, saving-to-investment ratio (SIR) is evaluated for two parts: the basic part (SIRI) for block I; the extra parts (SIRII-I, SIRIII-I) for block II and block III. Over a thirty-year period the SIR is estimated to be 4.80, 2.14 and 3.18 for SIRI, SIRII-I and SIRIII-I, respectively. These findings suggest that block I has the highest economic profitability. Based on these evaluations, the acceptable drilling costs for block II and block III are also analyzed and discussed.
Thermal performance and economic evaluation of double U-tube borehole heat exchanger with three different borehole diameters
Luo, Jin (author) / Rohn, Joachim (author) / Bayer, Manfred (author) / Priess, Anna (author)
Energy and Buildings ; 67 ; 217-224
2013-08-16
8 pages
Article (Journal)
Electronic Resource
English
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