Modelling large ground source cooling systems in the Chalk aquifer of central London

摘要: Abstract The Cooling the Tube Programme was set up to implement London Underground9s intention mitigate future warming of underground system and control tunnel temperatures. As part this programme use groundwater from Chalk in open-loop systems considered for cooling a number stations model determined as requirement by Environment Agency assess impacts on aquifer. It seemed plausible that plumes injected, warmed water would interact hydraulically possibly also thermally with each other at some locations. Furthermore, Underground wished investigate any longer-term effects potential loss benefit. This paper provides an overview hydrogeological modelling approach adopted hydraulic thermal effect proposed schemes summarizes findings may be broader interest. A staged used guide refine modelling. Initially, analytical solutions were processes heat transport derive parameters field-scale test. results indicated that, even low fissure-to-matrix contact areas, is likely conducted far into matrix. Over longer time scales, significant occurs under- overlying formations available are less scoping calculations scale. Distributed, finite-element, numerical models constructed simulate interactions within groups ground source specific operating conditions single schemes. Extensive sensitivity analysis carried out level uncertainty predictions, relative various parameters. greatest associated detailed aspects conceptual flow. Model sensitive assumed vertical distribution permeability Chalk. Additional selection appropriate boundary extent interaction formations. Uncertainty material had simulated performance systems. Operational conditions, such amount injected separation abstraction injection boreholes, assessed quantification significance these factors. work demonstrates equivalent MT3D FEFLOW give reasonable agreement both approaches feasible transport, density-driven flow not temperature differences