Ground heat transfer: Some further insights into the influence of three-dimensional effects

Abstract

The results of a numerical investigation of three-dimensional ground heat transfer are presented. In particular, the influence of varying floor slab geometry has been considered within an assessment of the importance of maintaining full three-dimensionality in the analysis of heat losses to the ground. A comparison is made between three-dimensional (3D) and two-dimensional (2D) representation of a particular series of test problems. The results obtained, for the specific problems analysed, suggest that two-dimensional simplification can lead to heat flux calculations that differ by at least 45% from the three-dimensional analysis of the problem. An analysis of the results is presented that can be used to aid the choice of analysis to be performed, estimate 3D behaviour from 2D analyses; and estimate the relative errors associated with 2D and 3D heat and flux calculations. The results achieved also help substantiate earlier findings that suggest that equations used to estimate heat flux should include reference to the area/perimeter ratio and not simply to the perimeter. One practical equation of this kind is suggested. Further work is required before more general conclusions can be made.

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