Borehole resistance and heat conduction around vertical ground heat exchangers

Sagia, Z; Stegou, A; Rakopoulos, C

dc.contributor.author	Sagia, Z	en
dc.contributor.author	Stegou, A	en
dc.contributor.author	Rakopoulos, C	en
dc.date.accessioned	2014-03-01T02:08:13Z
dc.date.available	2014-03-01T02:08:13Z
dc.date.issued	2012	en
dc.identifier.issn	18741231	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/29631
dc.subject	Borehole	en
dc.subject	Borehole thermal resistance	en
dc.subject	Geothermal	en
dc.subject	Ground heat exchanger	en
dc.subject	Heat conduction	en
dc.subject	Standard dimen-sion ratio	en
dc.subject.other	Borehole resistances	en
dc.subject.other	Borehole wall	en
dc.subject.other	Conductive heat flux	en
dc.subject.other	Dimensionless ratios	en
dc.subject.other	Geometrical parameters	en
dc.subject.other	Geothermal	en
dc.subject.other	Ground heat exchangers	en
dc.subject.other	Ground loop	en
dc.subject.other	Ground temperature	en
dc.subject.other	Major factors	en
dc.subject.other	Multi-physics	en
dc.subject.other	Outside diameter	en
dc.subject.other	Pipe diameter	en
dc.subject.other	Steady-state simulations	en
dc.subject.other	Temperature profiles	en
dc.subject.other	U-shaped tube	en
dc.subject.other	Working conditions	en
dc.subject.other	Working fluid	en
dc.subject.other	Factor analysis	en
dc.subject.other	Finite element method	en
dc.subject.other	Grouting	en
dc.subject.other	Heat conduction	en
dc.subject.other	Heat flux	en
dc.subject.other	Heat pump systems	en
dc.subject.other	Mortar	en
dc.subject.other	Thermal conductivity	en
dc.subject.other	Tubes (components)	en
dc.subject.other	Boreholes	en
dc.title	Borehole resistance and heat conduction around vertical ground heat exchangers	en
heal.type	journalArticle	en
heal.identifier.primary	10.2174/1874123101206010032	en
heal.identifier.secondary	http://dx.doi.org/10.2174/1874123101206010032	en
heal.publicationDate	2012	en
heal.abstract	Borehole thermal resistance in Ground Heat Exchanger (GHE) installations is affected by several parameters such as geometrical attributes of heat exchanger in the borehole, pipes' characteristics and grout's thermal conductivity. A study is carried out to compare the values computed by Ground Loop Design (GLD) Software, GLD 2009, with three ana-lytical solutions for U-shaped tubes. The analysis is focused on dimensionless ratios of borehole geometrical parameters (borehole diameter to outside pipe diameter and shank spacing to borehole diameter) and pipes according to Standard Di-mension Ratio (SDR) and on eight common grouts. Finally, the effect of heat conduction in the borehole is examined by means of finite element analysis by Heat Transfer Module of COMSOL Multiphysics. A two-dimensional (2-D) steady-state simulation is done assuming working fluid temperatures for winter and summer conditions and typical Greek undis-turbed ground temperature in a field of four ground vertical U-tube heat exchangers surrounded by infinite ground. The temperature profile is presented and the total conductive heat flux from the pipe to the borehole wall per meter of length of ground heat exchanger is computed for pipes SDR11 (the outside diameter of the pipe is 11 times the thickness of its wall), SDR9 and SDR17 for summer working conditions and three different configurations. It is attempted to reach to comparative results for borehole thermal resistance value through different types of analysis, having considered the major factors that affect it and giving trends for the influence of each factor to the magnitude of its value. © Sagia et al.	en
heal.journalName	Open Chemical Engineering Journal	en
dc.identifier.doi	10.2174/1874123101206010032	en
dc.identifier.volume	6	en
dc.identifier.issue	1	en
dc.identifier.spage	32	en
dc.identifier.epage	40	en