A new modeling approach for improved ground temperature profile determination

Abstract

a b s t r a c tThe knowledge of the ground temperature profile with respect to time and depth is very important in many technological fields like geothermal heat pumps, solar energy systems and geotechnical applications. Many researches were performed in the past in order to evaluate this profile. The most common ones, known as energy balance models, use the energy balance equation as a boundary condition. Unfortunately the performance of these models strongly depends on an accurate estimation of several input factors. The objective of this paper is to develop an improved model for the prediction of the ground temperature profile in which the energy balance equation at the ground surface is supplemented by an empirical correlation for the annual average ground surface temperature calculation. This model is less sensitive to uncertainties of input factors. Furthermore, unlike the previous models, a periodic variation of the sky temperature is introduced instead of a previously assumed constant value. The model is validated against measured data in a site located in Varennes (Montreal-Canada) and two further sites, Fort Collins (Colorado) and Temple (Texas) in the U.S.A.

Undisturbed Ground Temperature—Different Methods of Determination

“…The ambient temperature T a , the temperature of the surface of the ground T s , and the solar radiation flux absorbed by the ground S change periodically in the yearly cycle, according to the following dependencies [12,13]:…”

“…Also, publications in which the observations from weather stations were correlated with meteorological parameters concerned the determination of the UGT. Recently, works concerning the UGT were reported by Ouzzane et al [4,11] and Badache et al [12].…”

Heat Pump Capacity Effects on Peak Electricity Consumption and Total Length of Self- and Solar-assisted Shallow Ground Heat Exchanger Networks

“…The heat pump coefficient of performance (COP), capacity and power consumption are loaded from external data files. Ground surface effects are considered by using a correlation (Badache et al 2016) for the calculation of the ground temperature at = for horizontal sections of pipes and for the calculation of the average ground temperature over ≤ ≤ + for boreholes.…”

Colloquium 2016: Assessment of subsurface thermal conductivity for geothermal applications

“…The undisturbed subsurface temperature can be inferred from maps of the shallow subsurface temperature interpolated between boreholes (Majorowicz et al 2009) or deduced according to atmospheric temperature data (Signorelli and Kohl 2004) using different analytical (Williams and Gold 1976) or empirical approaches (Badache et al 2016). A direct measurement of a temperature profile in a pilot GHE is an additional option to reduce uncertainty when designing a GCHP system (Gehlin and Nordell 2003).…”