New correlations for the prediction of the undisturbed ground temperature

Undisturbed Ground Temperature—Different Methods of Determination

“…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].…”

“…While designing equipment for heat extraction from the ground, the UGT value plays an important role, because the amount of heat that may be extracted is proportional to the difference between the UGT and the minimum temperature of the working liquid (resulting from its freezing temperature) [3]. If, while designing ground heat exchangers (GHE), yearly average ambient temperature is assumed as an approximation of the UGT value, it may lead to unjustified oversizing of the exchanger (when used for heating purposes) [4].…”

“…The T b values may be determined using correlations developed on the basis of meteorological data, which has been proposed by Ouzzane et al [4]. In their paper, the results of measurements collected from 15 locations with diversified climates are reported.…”

“…The values of the regression coefficients at the individual variables indicate the direction of changes in the T b value, which increases with an increasing ambient temperature and horizontal solar radiation, and it decreases with increasing wind velocity. In the same paper [4], a second empirical correlation with a simplified character is also shown, which takes into account only one independent variable: ambient temperature.…”

“…In this paper an attempt to use the data gathered in paper [4] to develop a correlation based on an integrated form of the heat balance equation for the surface of the ground is made. Therefore, the effect of the moisture stream evaporated from the surface of the ground was also taken into account.…”