2D thermal resistance of pile heat exchangers

Structural foundation piles are being used increasingly as heat exchangers to provide renewable heat for new buildings. To design such energy systems a steady state is assumed within the pile, which is conventionally characterised by constant thermal resistance. However, there has been little research regarding pile resistance and there are few published case studies. Numerical modelling results are presented here to provide typical values of pile resistance, depending on the details of the heat exchange pipes. Analysis suggests large diameter piles may take several days to reach steady state; in these cases a transient design approach may be more appropriate.

[1]  Fleur Loveridge,et al.  Pile heat exchangers: thermal behaviour and interactions , 2013 .

[2]  Mostafa H. Sharqawy,et al.  Effective pipe-to-borehole thermal resistance for vertical ground heat exchangers , 2009 .

[3]  J. Konrad,et al.  A generalized thermal conductivity model for soils and construction materials , 2005 .

[4]  Stanislaw Kajl,et al.  A review of methods to evaluate borehole thermal resistances in geothermal heat-pump systems , 2010 .

[5]  J. Beck,et al.  Field Test of a New Method for Determining Soil Formation Thermal Conductivity and Borehole Resistance , 2000 .

[6]  Burkhard Sanner,et al.  Thermal Response Test - Current Status and World-Wide Application , 2005 .

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

[8]  Xu Zhang,et al.  Numerical and experimental assessment of thermal performance of vertical energy piles: An application , 2008 .

[9]  Z. Fang,et al.  Improvement in Modeling of Heat Transfer in Vertical Ground Heat Exchangers , 2004 .

[10]  Frank P. Incropera,et al.  Fundamentals of Heat and Mass Transfer , 1981 .

[11]  D. J. Lennon,et al.  Energy piles in Scotland , 2008 .

[12]  G. Hellström,et al.  Multipole method to compute the conductive heat flows to and between pipes in a composite cylinder , 1987 .

[13]  A. Neville.  Properties of Concrete , 1968 .

[14]  Jin-keun Kim,et al.  An experimental study on thermal conductivity of concrete , 2003 .

[15]  Saffa Riffat,et al.  Comparison of a modelled and field tested piled ground heat exchanger system for a residential building and the simulated effect of assisted ground heat recharge , 2010 .

[16]  David Banks,et al.  Practical Engineering Geology , 2008 .