A novel hybrid design algorithm for spiral coil energy piles that considers groundwater advection

Abstract This paper presents a novel hybrid design algorithm for spiral coil energy piles that considers groundwater advection. The design algorithm considers the groundwater advection effect using an analytical model. During this study, the accuracy of the analytical model was verified for its design application using a finite element (FE) numerical model, and the effect of groundwater advection on the design results was investigated. According to these results, groundwater advection attenuates thermal interference between piles, as well as long-term ground thermal resistance, which contributes to the economical design of energy piles. Moreover, when there is an extreme disparity between cooling and heating loads, hybrid design was achieved using hourly building energy load data calculated by the design builder program. Hybrid design decreases the total heat exchanger length of the energy piles, and reduces the entering water temperature (EWT) variance caused by heat interference. Furthermore, the pile arrangement can influence the impact caused by separation distance. For a square arrangement of piles, the shorter the separation distance, the less the effect from the hybrid system. In contrast, for a linear arrangement of piles, there is no influence caused by the separation distance, and generally, a high reduction rate of heat exchanger length is shown.

[1]  O. J. Zobel,et al.  Heat conduction with engineering and geological applications , 1948 .

[2]  Hyunku Park,et al.  Evaluation of thermal response and performance of PHC energy pile: Field experiments and numerical simulation , 2013 .

[3]  Onder Ozgener,et al.  A practical approach to predict soil temperature variations for geothermal (ground) heat exchangers applications , 2013 .

[4]  Zhihao Chen,et al.  Experimental investigation on the operation performance of a direct expansion ground source heat pump system for space heating , 2013 .

[5]  Javier F. Urchueguía,et al.  Efficiency improvement of a ground coupled heat pump system from energy management , 2011 .

[6]  Jeffrey D. Spitler,et al.  Comparative Study of Operating and Control Strategies for Hybrid Ground-Source Heat Pump Systems Using a Short Time Step Simulation Model , 2000 .

[7]  Yi Man,et al.  Development of spiral heat source model for novel pile ground heat exchangers , 2011 .

[8]  Sang-Seom Jeong,et al.  Thermal Influential Factors of Energy Pile , 2010 .

[9]  Onder Ozgener,et al.  An experimental study of the exergetic performance of an underground air tunnel system for greenhouse cooling , 2010 .

[10]  Hangseok Choi,et al.  Relative constructability and thermal performance of cast-in-place concrete energy pile: Coil-type GHEX (ground heat exchanger) , 2015 .

[11]  Yong Chan Kim,et al.  Transient performance characteristics of a hybrid ground-source heat pump in the cooling mode , 2014 .

[12]  Abdeen Mustafa Omer,et al.  Ground-source heat pumps systems and applications , 2008 .

[13]  C. D. Rakopoulos,et al.  Cooling dominated Hybrid Ground Source Heat Pump System application , 2012 .

[14]  Seung-Rae Lee,et al.  Thermal transfer behavior in two types of W-shape ground heat exchangers installed in multilayer soils , 2014 .

[15]  K. Zhu,et al.  A moving finite line source model to simulate borehole heat exchangers with groundwater advection , 2011 .

[16]  Yi Man,et al.  Heat transfer analysis of pile geothermal heat exchangers with spiral coils , 2011 .

[17]  Georgios A. Florides,et al.  Ground heat exchangers—A review of systems, models and applications , 2007 .

[18]  Honghyun Cho,et al.  Performance comparison between R22 and R744 solar-geothermal hybrid heat pumps according to heat source conditions , 2014 .

[19]  Seung-Rae Lee,et al.  Design of spiral coil PHC energy pile considering effective borehole thermal resistance and groundwater advection effects , 2014 .

[20]  Sophie Didierjean,et al.  Thermal dispersion in porous media: one-equation model , 2000 .

[21]  Onder Ozgener,et al.  Experimental prediction of total thermal resistance of a closed loop EAHE for greenhouse cooling system , 2011 .

[22]  Stephen P. Kavanaugh,et al.  Ground Source Heat Pumps : Design of Geothermal Systems for Commercial and Institutional Buildings , 1997 .

[23]  Onder Ozgener,et al.  Exergoeconomic analysis of an underground air tunnel system for greenhouse cooling system , 2010 .

[24]  Hyunku Park,et al.  Case study of heat transfer behavior of helical ground heat exchanger , 2012 .

[25]  Zhaohong Fang,et al.  The research on ring-coil heat transfer models of pile foundation ground heat exchangers in the case of groundwater seepage , 2014 .

[26]  Jinggang Wang,et al.  Study on hybrid ground-coupled heat pump system for air-conditioning in hot-weather areas like Hong Kong , 2010 .

[27]  D. Nutter,et al.  A Ground Resistance for Vertical Bore Heat Exchangers With Groundwater Flow , 2003 .

[28]  M. Moreni,et al.  Comportement d'un pieu bi-fonction, fondation et échangeur de chaleur , 2003 .

[29]  H. Brandl.  Energy foundations and other thermo-active ground structures , 2006 .

[30]  Alvin C.K. Lai,et al.  New temperature response functions (G functions) for pile and borehole ground heat exchangers based on composite-medium line-source theory , 2012 .

[31]  Dirk Müller,et al.  Numerical study on hybrid heat pump systems in existing buildings , 2014 .

[32]  Yan Gao,et al.  Thermal performance and operation strategy optimization for a practical hybrid ground-source heat-pump system , 2014 .

[33]  Yang Hongxing,et al.  Study on hybrid ground-coupled heat pump systems , 2008 .

[34]  Hongxing Yang,et al.  A new model and analytical solutions for borehole and pile ground heat exchangers , 2010 .

[35]  Michele De Carli,et al.  Thermal performance of two types of energy foundation pile: Helical pipe and triple U-tube , 2013 .

[36]  Lin Lu,et al.  Investigation on heat transfer around buried coils of pile foundation heat exchangers for ground-coupled heat pump applications , 2012 .

[37]  O. Boënnec,et al.  Shallow ground energy systems , 2008 .

[38]  Shengwei Wang,et al.  Performance analysis of hybrid ground source heat pump systems based on ANN predictive control , 2014 .

[39]  Onder Ozgener,et al.  Use of solar assisted geothermal heat pump and small wind turbine systems for heating agricultural and residential buildings , 2010 .

[40]  Min-Soo Kim,et al.  Performance investigation of heat pump–gas fired water heater hybrid system and its economic feasibility study , 2014 .

[41]  Hyunku Park,et al.  Characteristics of an analytical solution for a spiral coil type ground heat exchanger , 2013 .

[42]  Z. Fang,et al.  Heat transfer in ground heat exchangers with groundwater advection , 2004 .

[43]  I. Dincer,et al.  Thermodynamic analysis of a hybrid geothermal heat pump system , 2011 .

[44]  Daniel Pahud,et al.  Heat exchanger pile system for heating and cooling at Zürich airport. , 1999 .